Changes in afferent and efferent phrenic activities with electrically induced diaphragmatic fatigue. In anesthetized artificially ventilated cats, diaphragmatic fatigue was produced by direct muscle stimulation with trains of pulses for 30 min. Failure of contraction was assessed from decrease in the maximal relaxation rate of transdiaphragmatic pressure twitches. Motor activities (electromyogram and motor phrenic neurogram) were processed by fast-Fourier transform analysis, which provided the power spectrum density function (PSDF). The discharge frequency of diaphragmatic afferents was also measured. In control conditions (before fatigue), intra-arterial bolus injection of lactic acid enhanced tonically active diaphragmatic afferents, whereas it reduced the firing rate of afferent fibers activated in phase with diaphragmatic contraction or relaxation. The same sensory response pattern was observed with the development of diaphragmatic fatigue. Leftward shift in PSDFs of motor phrenic neurogram also occurred, but it preceded the failure of diaphragmatic contraction as well as the changes in the electromyogram's PSDF and afferent paths, which were closely associated with lengthening of both inspiratory and total breath durations. After section of the phrenic nerves, the motor phrenic response disappeared during the fatigue trial. This demonstrates the existence of complex reflex-induced changes in the ventilatory control during diaphragmatic fatigue. They seem to involve the participation of several types of phrenic afferents.


Fluid ingestion during exercise increases skin blood flow independent of increases in blood volume. The purpose of this experiment was to determine whether fluid ingestion attenuates the hyperthermia and cardiovascular drift that occurs during exercise dehydration due to increases in blood volume. In addition, forearm blood flow, which is indicative of skin blood flow, was measured to determine whether the attenuation of hyperthermia and cardiovascular drift during exercise with fluid ingestion is due to higher skin blood flow. On three different occasions, seven trained cyclists [mean age, body weight, and maximum oxygen uptake: 23 +/- 3 yr, 73.9 +/- 10.5 kg, and 4.75 +/- 0.34 (SD) l/min, respectively] cycled at a power output equal to 62-67% maximum oxygen uptake for 2 h in a warm environment (33 degrees C, 50% relative humidity, wind speed 2.5 m/s). During exercise, they randomly received no fluid (NF) or a volume of a carbohydrate-electrolyte fluid replacement solution (FR) sufficient to replace 80 +/- 2% of sweat loss or were intravenously infused with 5.3 ml/kg of a blood volume expander (BVX; 6% dextran in saline). The infusion of 398 +/- 23 ml of BVX maintained blood volume at levels similar to that when 2,404 +/- 103 ml of fluid were ingested during FR and greater than that when no fluid was ingested during the 2nd h of exercise (P less than 0.05). However, BVX and NF resulted in similar esophageal and rectal temperatures, forearm blood flow, and elevations in serum osmolality and sodium concentration during 2 h of exercise.(ABSTRACT TRUNCATED AT 250 WORDS)


Adaptations in coactivation after isometric resistance training. Twenty sedentary male university students were randomly assigned to an experimental or a control group. The experimental group trained the knee extensors of one leg by producing 30 isometric extension maximal voluntary contractions (MVC) per day, three times per week for 8 wk. After 8 wk of training, extensor MVC in the trained leg increased 32.8% (P less than 0.05), but there was no change in vastus lateralis maximal integrated electromyographic activity (IEMGmax). The most important finding was that the degree of hamstring coactivation during extension MVC decreased by approximately 20% (P less than 0.05) after the 1st wk of training. Less pronounced adaptations occurred in the untrained leg: extension MVC force increased 16.2% (P less than 0.05), hamstring coactivity decreased 13% (P less than 0.05) after 2 wk of training, and vastus lateralis IEMGmax was unchanged. The same measures in legs of the control group were not changed during the study. There were no changes in flexion MVC, biceps femoris IEMGmax, or the degree of quadriceps coactivity during flexion MVC in either leg of the control or experimental group. A reduction in hamstring coactivity in the trained and untrained legs indicates that these muscles provide less opposing force to the contracting quadriceps. We conclude that this small but significant decrease in hamstring coactivation that occurs during the early stages of training is a nonhypertrophic adaptation of the neuromuscular system in response to static resistance training of this type.


Technique-dependent variations in cerebral microvessel blood volumes and hematocrits in the rat. To quantitate small parenchymal microvessel blood volumes in the brain, the distribution spaces of radiolabeled red blood cells (RBC) and serum albumin (RISA) were assessed in rats by different methods of tissue sampling and radioassay. Three minutes after intravenous administration of 55Fe-RBCs and/or 125I-RISA, the rats were decapitated. The brain was either immediately frozen within the skull and later removed (head-frozen group) or rapidly removed from the skull and then frozen (brain-frozen group). Radioactivity was measured either by liquid scintillation counting of tissue pieces, which contained pial plus large and small parenchymal microvessels, or by quantitative autoradiography (QAR) of tissue sections, which indicated small parenchymal microvessel blood only. In 12 of 15 areas, the RISA, RBC, and blood volumes determined by liquid scintillation counting of head-frozen tissue pieces were equal to or greater than those of brain-frozen tissue; this indicated less than or equal to 25% greater blood retention in pial and parenchymal microvessels with head freezing. At the parenchymal microvessel level (QAR assay), the distribution volumes of RBCs, RISA, and blood were similar with the two freezing techniques; hence with QAR either freezing procedure can be used to assess small parenchymal microvessel blood volumes.


Effects of ibuprofen and pentoxifylline on the cardiovascular response of normal humans to endotoxin. Endotoxin is a major mediator of the life-threatening cardiovascular dysfunction that characterizes Gram-negative sepsis. In animal models of endotoxemia, pretreatment with ibuprofen or pentoxifylline attenuates some of these cardiovascular changes. To evaluate the effects of these agents on the human cardiovascular response to endotoxemia, hemodynamic variables were measured serially in 24 normal subjects who were given intravenous endotoxin. The subjects were randomized to receive oral ibuprofen (n = 9), pentoxifylline (n = 10), or no medication before endotoxin administration (n = 5). The subjects were volume loaded 3-5 h after endotoxin administration, and hemodynamic measurements were reassessed. Core temperature after endotoxin alone or endotoxin-pentoxifylline approached a maximum at 3 h (greater than or equal to 38.6 degrees C), while the endotoxin-ibuprofen group remained afebrile. At 3 and 5 h, all three groups had significant increases in heart rate, cardiac index, oxygen delivery, and oxygen consumption, while systemic vascular resistance index decreased significantly from baseline. The oxygen extraction ratio remained unchanged. After volume loading, the left ventricular ejection fraction and left ventricular end-diastolic and end-systolic volume indexes did not differ among the groups. The hyperdynamic cardiovascular response to endotoxin in humans occurs in the absence of fever and is not significantly ameliorated by oral cyclooxygenase or phosphodiesterase inhibition.


Vasopressin inhibits diuresis induced by water immersion in humans. We tested the hypothesis that 1-desamino-8-D-arginine vasopressin (DDAVP), a V2-receptor agonist, could inhibit the diuresis induced by water immersion in humans. Water and electrolyte excretion, plasma atrial natriuretic factor concentration, and plasma aldosterone concentration were measured initially and after 3 h of water immersion in 13 healthy sodium-replete men given either placebo or 20 micrograms of intranasal DDAVP. Guanosine 3',5'-cyclic monophosphate and urea excretion and urine osmolality were also determined. DDAVP inhibited the diuresis induced by water immersion in men: 758 +/- 168 (SE) ml/3 h in the placebo group vs. 159 +/- 28 ml/3 h in the DDAVP group (P less than 0.05). After 3 h of water immersion, plasma atrial natriuretic factor concentrations were increased from 11 +/- 2 to 20 +/- 4 pg/ml in the placebo group and from 14 +/- 2 to 33 +/- 4 pg/ml in the DDAVP group (P less than 0.05). Plasma aldosterone concentrations were decreased from 98 +/- 18 to 45 +/- 6 pg/ml in the placebo group (P less than 0.05) and from 54 +/- 17 to 25 +/- 5 pg/ml in the DDAVP group (P less than 0.05). Despite these changes in aldosterone and atrial natriuretic factor concentrations, which should increase sodium excretion, DDAVP decreased the natriuresis induced by water immersion in humans: 56 +/- 8 meq Na+/3 h in the placebo group vs. 36 +/- 6 meq Na+/3 h in the DDAVP group (P less than 0.05). DDAVP may be used to prevent the diuresis associated with central redistribution of blood volumes that occur during water immersion.(ABSTRACT TRUNCATED AT 250 WORDS)


Use of arterialized venous blood sampling during incremental exercise tests. Close agreement between arterialized venous and arterial pH, PCO2, and lactate has previously been demonstrated during steady-state exercise. The purpose of the present study was to compare arterialized venous and arterial pH, PCO2, K+, lactate, pyruvate, and epinephrine during the constantly changing circumstances of an incremental exercise test. Eight normal subjects undertook an incremental exercise test (increasing by 20 W/min) to exhaustion on a cycle ergometer during which simultaneous arterial and arterialized venous samples were drawn over the last 20 s of each work load. Linear regression of arterialized venous on arterial values showed that r varied from 0.97 to 0.99 for the variables examined and, therefore, showed that accurate estimates of arterial values could be made from the arterialized venous results during incremental testing. For many purposes it could be assumed that arterialized venous values equaled arterial values without serious error.


Phospholipases introduced into the hypophase affect the surfactant film outlining a bubble. The hypophase exchanger is a recently developed device that makes it possible to replace the liquid in the sample chamber of a pulsating bubble surfactometer, after a bubble has been formed, without changing the size of the bubble. A surfactant film outlining the bubble will retain its surface properties, provided the liquid entering the sample chamber and replacing the hypophase is inert. If, on the other hand, the new hypophase consists of a phospholipase solution, the physical properties of the film are seriously affected. It was found that when phospholipase C, even at low concentration, entered the sample chamber, the physical properties were significantly changed. Phospholipase A2 had to be added at a higher concentration to exert a similar effect. It is postulated that the site of action of phospholipase A2 may be partly protected in the hydrophobic region of the tightly packed surfactant film.


Rib cage shape and motion in microgravity. We studied the effect of microgravity (0 Gz) on the anteroposterior diameters of the upper (URC-AP) and lower (LRC-AP) rib cage, the transverse diameter of the lower rib cage (LRC-TR), and the xiphipubic distance and on the electromyographic (EMG) activity of the scalene and parasternal intercostal muscles in five normal subjects breathing quietly in the seated posture. Gastric pressure was also recorded in four subjects. At 0 Gz, end-expiratory LRC-AP and xiphipubic distance increased but LRC-TR invariably decreased, as did end-expiratory gastric pressure. No consistent effect was observed on tidal LRC-TR and xiphipubic displacements, but tidal changes in URC-AP and LRC-AP were reduced. Although scalene and parasternal phasic inspiratory EMG activity tended to decrease at 0 Gz, both muscle groups demonstrated an increase in tonic activity. We conclude that during brief periods of weightlessness 1) the rib cage at end expiration is displaced in the cranial direction and adopts a more circular shape, 2) the tidal expansion of the ventral rib cage is reduced, particularly in its upper portion, and 3) the scalenes and parasternal intercostals generally show a decrease in phasic inspiratory EMG activity and an increase in tonic activity.


Prolonged pulmonary hypertension caused by platelet-activating factor and leukotriene C4 in the rat lung. Platelet-activating factor (PAF) and leukotrienes (LTs) are potent pulmonary hypertensive and inflammatory mediators produced by the lung. Previously we showed that a rapid injection of PAF into the pulmonary artery of an isolated rat lung produced an extended elevation in mean pulmonary arterial pressure (PAP). The objective of the present study was to determine whether the extended pressor response induced by PAF was caused by prolonged activation of the 5-lipoxygenase pathway or slow clearance of LTs from the lung parenchyma. Rat lungs were perfused with a nonrecirculating physiological salt solution that contained indomethacin and albumin. Five minutes after a rapid injection of PAF into the pulmonary artery catheter, the following elevations (mean % above baseline) were observed: PAP (83%), LTB4 (3,260%), LTC4 (1,490%), LTD4 (970%), and LTE4 (1,500%). At 20 min these levels declined but were still significantly elevated above baseline. The 5-lipoxygenase inhibitor diethylcarbamazine (DEC), administered before the PAF injection, inhibited the elevations of PAP and all LTs. DEC administration that began 5 min after PAF reduced PAP and only LTC4 levels at 20 min in comparison to lungs with no DEC. The 5-lipoxygenase-activating protein inhibitor MK886, administered orally 2-6 h before perfusion, also inhibited the pressor response to PAF as well as LT production, as did DEC. We conclude that 1) the extended pulmonary hypertension induced by PAF was caused mainly by prolonged activation of 5-lipoxygenase with LTC4 production, 2) the relative overall lung clearance of LTB4, LTD4, and LTE4 was slower than that of LTC4, and 3) LTB4, LTD4, and LTE4 had no appreciable pressor effect.


ACE inhibition facilitates sodium and water excretion during PEEP in conscious volume-expanded dogs. Increased activity of the renin-angiotensin system may be involved in sodium and water retention during controlled mechanical ventilation (CMV) with positive end-expiratory pressure (PEEP). We therefore evaluated renal, hemodynamic, and hormonal effects of an acute angiotensin-converting enzyme inhibition (ACEI) during PEEP and extracellular volume expansion in five trained chronically tracheotomized dogs. Three protocols were performed: control, 4 h spontaneous breathing with continuous positive mean airway pressure (Paw) of 4 cmH2O (CPAP 4); CMV 20, CPAP for 1st h, CMV with 20 cmH2O Paw for 2 h (2nd and 3rd h), and 1 h of CPAP (4th h); and CMV20-ACEI, ACEI (Ramipril, 2 mg/kg body wt) followed by the same protocol as in CMV 20. During control, sodium excretion (UNaV) and urine volume (V) increased continuously to 56.2 +/- 2.7 (SE) mumol.min-1.kg body wt-1 and 482 +/- 23 microliters.min-1.kg body wt-1, respectively. UNaV and V increased less during PEEP in CMV 20 and CMV 20-ACEI. However, significantly more sodium and water were retained in CMV 20 than in CMV 20-ACEI (2.3 +/- 0.3 vs. 1.0 +/- 0.3 mmol/kg body wt, and 20 +/- 3 vs. 11 +/- 2 ml/kg body wt) because of a decrease of glomerular filtration rate and fractional UNaV in CMV 20. Heart rate did not change in control, CMV 20, or CMV 20-ACEI. Mean arterial pressure increased during control by 13 mmHg, did not change during CMV 20, and was decreased by 7 mmHg in CMV 20-ACEI.(ABSTRACT TRUNCATED AT 250 WORDS)


Effect of downhill running on motoneuron pool excitability. The purpose of this study was to compare alterations in motoneuron pool excitability after eccentric-biased (ECC-B) downhill running exercise with non-biased (NO-B) level running exercise. Six male subjects (25-34 yr) participated in the study, which included ECC-B exercise (-10% grade) and NO-B exercise (0% grade) at 50% of maximal O2 uptake for 20 min. The control trial consisted of 20 min of quiet rest with all subjects participating in all conditions (repeated measures). Motoneuron pool excitability was measured by the Hoffman reflex (H-wave), which was expressed as a ratio (H/M ratio) of the maximal electrically stimulated muscle action potential (M-wave). NO-B exercise resulted in a 9.3 +/- 2.7% (SE) reduction in the H/M ratio. ECC-B exercise resulted in a 24.6 +/- 5.7% reduction in the ratio (P less than 0.05 for both). The two exercise treatment conditions were also significantly different from one another (P less than 0.05). Twenty-four-hour postexercise H/M ratios were similar to baseline (P greater than 0.05). Postexercise subjective muscle soreness assessment (DOMS) produced significant increases in DOMS of 36 and 166% immediately and 24 h after exercise, respectively, for the ECC-B trial only (P less than 0.001). The data show that ECC-B exercise results in greater postexercise H/M ratio reductions than NO-B exercise and that H/M ratio changes post-ECC-B exercise are not solely associated with DOMS.


Effect of acute nutritional deprivation on diaphragm structure and function in adolescent rats. The influence of 90 h of acute nutritional deprivation (ND; water ad libitum only) on in vitro contractile and fatigue properties, muscle fiber type proportions, and cross-sectional areas (CSA) of the adolescent rat diaphragm was determined. Diaphragm muscle properties in the ND rats were compared with those in control rats (CTL; food and water ad libitum). Acute ND resulted in a 32% reduction in body mass, whereas the body mass of CTL rats increased by 29%. Acute ND resulted in a significant reduction in the mass of the diaphragm (costal, 36%; crural, 43%), soleus (36%), and medial gastrocnemius (45%) muscles. Isometric twitch characteristics of the diaphragm muscle (contraction and half-relaxation times) were prolonged in the ND animals. Peak twitch and maximum tetanic forces were unaffected by ND. Fatigue resistance of the diaphragm muscle was improved in ND animals. Diaphragm muscle fiber type proportions were similar in ND and CTL groups. The CSA of type I and II diaphragm muscle fibers were reduced by 22 and 40%, respectively, in ND animals compared with CTL. We conclude that, whereas an identical protocol of acute ND had no significant effects on diaphragm muscle structure and function in adult rats, adolescent animals exhibit significantly less nutritional reserve. These differences may be due to curtailment of the rapid anabolic rate in growing animals.


Parasternal and external intercostal responses to various respiratory maneuvers. Recent studies suggest that the external intercostal (EI) muscles of the upper rib cage, like the parasternals (PA), play an important ventilatory role, even during eupneic breathing. The purpose of the present study was to further assess the ventilatory role of the EI muscles by determining their response to various static and dynamic respiratory maneuvers and comparing them with the better-studied PA muscles. Applied interventions included 1) passive inflation and deflation, 2) abdominal compression, 3) progressive hypercapnia, and 4) response to bilateral cervical phrenicotomy. Studies were performed in 11 mongrel dogs. Electromyographic (EMG) activities were monitored via bipolar stainless steel electrodes. Muscle length (percentage of resting length) was monitored with piezoelectric crystals. With passive rib cage inflation produced either with a volume syringe or abdominal compression, each muscle shortened; with passive deflation, each muscle lengthened. During eupneic breathing, each muscle was electrically active and shortened to a similar degree. In response to progressive hypercapnia, peak EMG of each intercostal muscle increased linearly and to a similar extent. Inspiratory shortening also increased progressively with increasing PCO2, but in a curvilinear fashion with no significant differences in response among intercostal muscles. In response to phrenicotomy, the EMG and degree of inspiratory shortening of each intercostal muscle increased significantly. Again, the response among intercostal muscles was not significantly different.(ABSTRACT TRUNCATED AT 250 WORDS)


A simple distensible vessel model for interpreting pulmonary vascular pressure-flow curves. A simple distensible vessel model was developed for the purpose of interpreting the vascular pressure-flow curve in the zone 3 lung. The model-governing equation has two parameters: R0, representing the hemodynamic resistance of the undistended pulmonary vascular bed, and alpha, representing the distensibility of the resistance vessels. To evaluate the model, the governing equation was used in a nonlinear regression analysis of the pressure-flow data from isolated dog lung lobes. The dependency of the estimates of the model parameters in response to changes in perfusate viscosity (hematocrit) was determined. The distensible vessel model provided reasonable fits to the data, and, as predicted, R0, but not alpha, was hematocrit dependent. On the other hand, the traditional linear ohmic-Starling resistor model fit to the same pressure-flow data generally provided fits approaching those of the distensibility model only if the pressure intercept (the mean "critical closing pressure") was allowed to increase with hematocrit. Because the ohmic-Starling resistor concept does not predict a hematocrit dependence of the critical closing pressure, this latter observation is evidence that the distensible vessel model offers an alternative conceptualization of the pulmonary circulation worthy of additional study with respect to the interpretation of experimental pressure-flow data.


Respiratory phasic effects of inspiratory loading on left ventricular hemodynamics in vagotomized dogs. Exaggerated inspiratory swings in intrathoracic pressure have been postulated to increase left ventricular (LV) afterload. These predictions are based on measurements of LV afterload by use of esophageal or lateral pleural pressure. Using direct measurements of pericardial pressure, we reexamined respiratory changes in LV afterload. In 11 anesthetized vagotomized dogs, we measured arterial pressure, LV end-systolic (ES) and end-diastolic transmural (TM) pressures, stroke volume (SV), diastolic left anterior descending blood flow (CBF-D), and coronary resistance. Dogs were studied before and while breathing against an inspiratory threshold load of -20 to -25 cmH2O compared with end expiration. Relative to end expiration, SV and LVES TM pressures decreased during inspiration and increased during early expiration, effects exaggerated during inspiratory loading. In all cases, LV afterload (LVES TM pressure) changed in parallel with SV. LV end-diastolic TM pressure did not change. CBF-D paralleled arterial pressure, and there were no changes in coronary resistance. In two dogs, regional LVES segment length paralleled calculated changes in LVES TM pressure. We conclude that 1) LV afterload decreases during early inspiration and increases during early expiration, changes secondary to those in SV; 2) changes in CBF-D are secondary to changes in perfusion pressure during the respiratory cycle; and 3) the use of esophageal or lateral pleural pressure to estimate LV surface pressure overestimates changes in LV TM pressures during respiration.


Biology of inherited coagulopathies: von Willebrand factor. von Willebrand disease is a common inherited bleeding disorder due to qualitative or quantitative abnormalities in von Willebrand factor. This article reviews the progress that has been made over the past few years in defining the molecular basis of von Willebrand disease. It should soon be possible to precisely diagnose and classify many cases of von Willebrand disease using modern genetic techniques.


Hemophilia A.

Hemophilia A. Over the past few years considerable progress has been made in elucidating the molecular genetics of hemophilia A, in carrier detection and prenatal diagnosis, and in the production of safer clotting factor concentrates. Recombinant FVIII, shown to be safe and effective in ongoing prelicensure clinical trials that began in the spring of 1987, should soon be licensed and commercially available. There is now considerable interest in beginning prophylactic therapy regimens at 1 or 2 years of age, in an attempt to prevent chronic joint disease and other complications of serious bleeding episodes. The possibility of gene insertion therapy for persons with hemophilia now seems to be a realistic one--perhaps achievable in the 1990s. Although many problems remain--major problems resulting from HIV, HCV, and HBV infections; how to deal with existing musculoskeletal problems; how to pay for the higher-priced new technologies; high titer inhibitors; just to name a few--the many recent scientific advances and their clinical applications make this an exciting time. This is truly, as indicated in the title of the proceedings of the XIX Congress of the World Federation of Hemophilia, a new decade of hopes and challenges.


Management of hemophilia patients with inhibitors. rFVIIa seems to offer an alternative in the treatment of hemophiliacs as well as nonhemophiliacs with antibodies against FVIII/FIX. The treatment can be given regardless of the inhibitor titer in those patients and is also hemostatically active in hemophilia B patients. It is easy to administer but seems to need a repeated dosing at 2- to 3-hour intervals, at least initially in severe bleedings. A dose of 70 to 100 micrograms/kg body weight seems to induce hemostasis. Depending on the severity of the bleeding, the dose intervals may then be prolonged to 3 hours for 1 to 2 days or until clinical improvement is observed. Thereafter, the dosage interval can be increased to 4 hours if continued therapy is indicated.


The safety of blood components and derivatives. An overview of the steps taken to ensure the safety of blood components and derivatives is provided. A brief discussion of hereditary bleeding disorders (hemophilia A, B, and von Willebrand's disease) is included, and the safety of derivatives available for their treatment is discussed, as well as the method of production and the level of safety of derivatives such as factor VIII and factor IX concentrates.


Treatment of von Willebrand's disease.

Treatment of von Willebrand's disease. Recent unraveling of the molecular and cellular biology of vWF and clearer knowledge of the pathophysiology of vWD have dramatically advanced our understanding of this group of disorders. Nonetheless, safe, effective, therapeutic management remains a formidable challenge for the clinician caring for these patients.


Considerations for using lower doses of warfarin. Warfarin is a very effective anticoagulant when used in the standard dose; however, the definition of standard dose has become ambiguous as the importance of the thromboplastin used in the measure of the prothrombin times has been demonstrated. Full or "standard" anticoagulation with warfarin imposes a hemorrhagic risk that can be avoided using lower doses. The premise has now been established that less than standard doses are efficacious. What is yet to be determined, however, is how low the dose of warfarin may be while maintaining efficacy and in which clinical settings. These conclusions must be established cautiously in clinical settings before being advocated generally. More complete discussions of this topic as well as safer means of using warfarin in general are available.


Antithrombin III concentrates.

Antithrombin III concentrates. The general characteristics of antithrombin III (AT III) concentrates available in the United States are described in this article. The effectiveness of AT III concentrates in the prevention and treatment of thrombotic episodes in patients with hereditary AT III deficiency are summarized, and the use of this product in various conditions with acquired AT III deficiency are reported.


Leeches to hirulogs and other thrombin-directed antithrombotics. Leeches have been used for various medicinal purposes since before written history. Bloodletting and leeching declined with the advent of modern medicine. Nevertheless, the European medicinal leech has made a comeback in reattachment and plastic surgery. The antithrombotic substance of this leech is the small protein, hirudin, which has recently been cloned and advanced as an antithrombotic. From speculating how hirudin interacted with thrombin and before knowledge of the crystallographic structures of hirudin-thrombin complexes, the bridge-binding double-ligand concept was born and led to the highly specific thrombin inhibitors of the hirulog class. Like heparin, hirulogs and recombinant hirudins are not orally active but should fill needs where heparin and its derivatives have shortcomings. On the other hand, they most likely will be supplanted by small-molecule thrombin inhibitors when sufficiently specific and nontoxic ones are found. Other approaches to antithrombotic therapy include modulating cellular functions of thrombin. Because thrombin has central bioregulatory functions in thrombosis and hemostasis, as well as wound healing, it is an attractive target for antithrombotic intervention.


Noninvasive carotid duplex ultrasound imaging for the evaluation and management of carotid atherosclerotic disease. Renewed interest in surgical management of atherosclerotic disease of the carotid bifurcation underscores the necessity for accurate and efficacious means for diagnostic evaluation of patients with suspected carotid disease. Noninvasive testing by carotid duplex ultrasound, which combines high-resolution B-mode imaging with pulsed Doppler spectral analysis, is the method of choice. Noninvasive testing permits identification of potentially significant carotid stenosis, occlusion, or unstable plaque morphology with virtually no significant morbidity from the testing itself. Symptomatic patients, or patients with asymptomatic carotid bruits, can be evaluated serially to determine disease progression or response to medical management. In patients who are surgical candidates, substitution of noninvasive duplex ultrasound evaluation for carotid arteriography is controversial. Noninvasive testing is highly technique-dependent and probably requires at least 1 year of experience for acquisition of a sufficient "learning curve" for diagnostic reliability. This applies not only to the technical performance of the test but to interpretation of results. Proper training of technicians and quality assurance in individual vascular laboratories are crucial elements with respect to accuracy and reliability of results obtained in noninvasive testing.


Approach to the patient with venous thromboembolism. Treatment with thrombolytic agents. This article reviews the different thrombolytic agents currently available and the different mechanisms by which they activate the body's fibrinolytic system. The discussion is confined to the approach to the patient with venous thromboembolism using the different thrombolytic agents. Data are presented supporting the use of thrombolytic therapy and its long-term benefits, especially in patients with pulmonary embolism. A substantial portion of this article is devoted to practical considerations involved in the administration of thrombolytic therapy.


Current concepts in coronary thrombolysis. It has become increasingly apparent that the success of coronary thrombolysis depends on a dynamic balance between fibrinolytic and procoagulant activity. The differential properties of specific plasminogen activators determine the rate at which clot lysis is induced, the extent to which procoagulant activity and platelet activation are increased, and the extent to which recurrent thrombosis is inhibited. Current conjunctive regimens (aspirin and heparin) appear to attenuate but not preclude recurrent thrombosis in patients treated with coronary thrombolysis. The recent development of a variety of new anticoagulants with different mechanisms of action may result in even more effective treatment strategies. Whether these newer agents will result in improved survival in patients treated with coronary thrombolysis without compromising safety will need to be established by clinical trials.


Fibrinogen anomalies and disease. A clinical update. The precipitous increase in the number of structurally defined fibrinogen defects in recent years has resulted from application of high performance liquid chromatography in combination with peptide mapping and sequencing procedures. More recently, application of DNA sequence of polymerase chain reaction products has accelerated the pace of identification of mutations. Highly frequent defects are Arg substitutions, accounting for eight mutation sites substituted by Cys or His and less frequently by Ser. Amino acid substitutions at different positions on all three chains have pointed to possible structures with polymerization-related functions. Also, substitutions yielding consensus sequences resulted in extra glycosylations of the appropriate Asn in four different mutation sites; the impaired polymerization was reported associated with undue bleeding in two of these. Among informative defects have been those of homozygous probands with A alpha 16Arg----His and A alpha 16Arg----Cys in that failure of release of peptide A (but not of B), as shown with A alpha 16Arg----Cys, resulted in markedly delayed polymerization of such fibrin monomers, in general agreement with conclusions reached in studies of normal fibrin. This dysfunction, as well as the slow rate of release of A shown with A alpha 16Arg----His, was associated with clinically significant hemorrhagic diathesis (in the homozygous probands), consistent with the known physiologic importance of peptide A cleavage in normal hemostasis. Also, defects on the A alpha 17-19 sequence resulting in impaired polymerization are consistent with the known role of this segment in polymerization. Of similar interest have been defects within a B beta chain span encoded its exon 2. Two defects resulting in impaired polymerization and thrombin binding were associated with clinical thrombosis commencing in early life, and this lends strong support to other evidence suggesting a role in polymerization and in noncatalytic thrombin binding by this B beta chain segment. Thrombosis associated with A alpha 554Arg----Cys in a heterozygous proband with impaired tPA interaction is unique and may shed light on this poorly understood but important interaction among fibrin, plasminogen, and tPA. A group of different defects within the gamma 275-375 sequence have pointed to a polymerization role, evidenced by delayed gelation and impaired binding of mutant D to normal fibrin E. An unusual example is a 15 residue insertion between gamma 350 and 351 resulting in impaired polymerization, gamma chain crosslinking, and platelet aggregation support and is associated with hemorrhagic diathesis and poor healing.(ABSTRACT TRUNCATED AT 400 WORDS)


Hemostatic aspects of envenomation by North American snakes. 1. North American poisonous snakes have a wide spectrum of complex venoms. 2. Venom, especially that of the rattlesnakes, may cause a variety of hemostatic abnormalities by directly, yet only partially, cleaving fibrinogen, activating the fibrinolytic system, or activating and clearing platelets through the action of proteolytic enzymes. 3. Because these venoms do not result in the generation of thrombin, the syndrome is distinct from true DIC. Bleeding or thrombosis is rare. 4. As thrombin generation remains intact, hemostasis is largely preserved despite dramatic changes in hemostatic tests. 5. Therapy with heparin, blood, or blood products is rarely indicated. 6. Therapy with antivenin in selected cases is logical and efficacious.


Approach to the bleeding patient.

Approach to the bleeding patient. A broad, open, inquisitive, and semiskeptical mind must be used when approaching the bleeding patient. As in most endeavors in medicine, the history and physical examination provide an important baseline. Key laboratory tests must be quickly ordered and interpreted. Using this data base, one can quickly determine whether the hemorrhagic disorder is congenital or acquired, severe or mild, and progressive or stable. Hemostasis may fail owing to deficiencies of platelets, the plasma coagulation protein system, or endothelial disturbances. A precise diagnosis and appreciation of the tempo of the disorder will guide specific therapy.


Biology of factor IX.

Biology of factor IX. Hemophilia B, one of two common hereditary bleeding disorders, is caused by a deficiency of factor IX in the circulation. Molecular mechanisms of hemophilia B are highly heterogeneous including gene deletions, insertions, complex rearrangements, and a large number of point mutations. Currently, hemophilia B is treated by plasma protein replacement therapy. This therapy is effective but exposes patients to possible side effects and complications such as infection of blood-borne pathogens including hepatitis viruses and HIV-1. Intensive efforts to develop alternative, safer therapies for hemophilia B, including somatic gene therapy, are now under way.


Acute hemorrhagic myocarditis in systemic lupus erythematosus. We report a 46-year-old patient with longstanding systemic lupus erythematosus (SLE) who developed rapidly progressive heart failure and died. At postmortem, there was a unique picture of hemorrhage and mild inflammation present in the myocardium causing the heart failure. As far as we are aware, this picture has not been described before in SLE and is similar to that seen in the cardiac allograft hyperacute rejection.


Ejecting volume, filling volume and stroke volume gains: new indexes of inotropism and lusitropism. We propose new indexes to evaluate the effects of ventricular inotropism and lusitropism on stroke volume. The end-systolic pressure-volume relationship (ESPVR) or its slope (Emax) has been employed to assess ventricular inotropism. The end-diastolic pressure-volume relationship (EDPVR) or compliance has been used to express ventricular diastolic properties or lusitropism. However, their net effect on stroke volume under a given set of preload and afterload pressures has not quantitatively been evaluated. Ejecting volume gain (Ge) was proposed to quantify the inotropic effect on stroke volume by the change in end-systolic volume between the two ESPVR curves obtained before and during an inotropic intervention at a specified ejecting pressure. Ge is a function of afterload pressure. Filling volume gain (Gf) was proposed to quantify the lusitropic effect on stroke volume by the change in end-diastolic volume between the two EDPVR curves before and during a lusitropic intervention at a specified filling pressure. Gf is a function of preload pressure. The net effect of these inotropic and lusitropic effects on stroke volume at these specified preload and afterload pressures can be expressed by the sum of Ge and Gf. We call this sum stroke volume gain (Gsv). Gsv is a function of preload and afterload pressures. Using representative examples, we demonstrate that these new indexes are conceptually useful to quantitatively understand changes in the pumping ability of the heart under simultaneous inotropic and lusitropic effects as a function of ejecting and filling pressures.


Usefulness of ultrasonography and Doppler color flow imaging in the diagnosis of internal jugular phlebectasia. A 20-year-old woman presented to our hospital for investigation of a left neck mass. Ultrasonographic examination of the jugular mass demonstrated an echo-free space, the caliber of which markedly increased when the patient shifted from the sitting to the recumbent position or performed a Valsalva maneuver. On color Doppler flow imaging, a slow flow signal flowing in the direction opposite to that of the common carotid artery was found within this space. Ultrasonography and color Doppler flow imaging thus proved to be useful for correctly diagnosing internal jugular phlebectasia.


Color Doppler and transesophageal echocardiography of vascular sling. Three patients with vascular sling were studied by two-dimensional and color Doppler echocardiography and angiocardiography. One case was associated with atrial septal defect and another with tetralogy of Fallot and patent ductus arteriosus. The third case had no associated intracardiac anomalies. Color Doppler flow mapping was performed in all three patients, and transesophageal echocardiography was studied in two patients. Color Doppler echocardiography showed the characteristic features of this congenital anomaly in all three patients, especially in detecting the site of anomalous origin of the left pulmonary artery. A small patent ductus arteriosus was misinterpreted as the normal left pulmonary artery in one patient. Small pulmonary arteries in the patient with tetralogy of Fallot made the diagnosis difficult. Using transesophageal echocardiography, we clearly identified the trachea, esophagus, and abnormal left pulmonary artery.


Knowledge of chemical abuse and AIDS among gifted junior high school students in Little Rock. A 12-question test was composed and administered to the seventh, eighth, and ninth grade Gifted-Talented (GT) Science Classes. A clustered stratified random sample of 66 students was selected out of the 194 students. The mean score was 70% for the eighth grade, 68% for the seventh grade, and 62% for the ninth grade. Knowledge among the students was especially deficient regarding the risk of legal drugs of abuse, i.e., cigarettes and alcohol.


Update of the worldwide FDA study of the 3M diffractive multifocal intraocular lens. The multifocal diffractive intraocular lens (IOL) represents a significant technological advance. Results of 671 patients with a year follow-up from a worldwide study are presented. Through this FDA study, it appears that many patients can enjoy uncompromising distance vision as well as unaided near vision. With careful surgical control of astigmatism and competent calculation of IOL power, it may be possible to reduce the post-cataract patients' dependency on glasses.


Torsion of the gallbladder. A review of four cases. Four cases of torsion of the gallbladder have been gathered from this area. Three were admitted to our local hospitals and the fourth case occurred in the Veteran's Hospital in Fayetteville. The average age of these four cases was 85, and all patients were very thin. Three patients were female and one was male. One patient died following surgery. This patient had sought help rather late, and died of cardiopulmonary complications. This entity is rare, and only scattered cases are found in the literature. Biliary calculi are found in approximately 50% of the cases. The exact etiology of the torsion is unknown. A redundant mesentery is always present, and kyphosis is frequent. Our patients were all thin. Botha has postulated that vigorous peristalsis in the neighboring viscera or sudden body movement may be responsible. The diagnosis is rarely made preoperatively, but if surgery is not done, death will probably ensue. Later reports have indicated that sonography and abdominal CT scanning might prove helpful in establishing a diagnosis.


Autism and tuberous sclerosis.

Autism and tuberous sclerosis. Autism is a behavior disorder with genetic influences indicated from twin and family studies and from the co-occurrence of autism with known genetic disorders. Tuberous sclerosis complex (TSC) is a known genetic disorder with behavioral manifestations including autism. A literature review of these two disorders substantiates a significant association of autism and TSC with 17-58% of TSC subjects manifesting autism and 0.4-3% of autistic subjects having TSC. In initial data collected on 13 TSC probands and 14 autistic probands in our family study of autism and TSC, we identified 7 TSC subjects with autism. The seven TSC autistic probands are similar to non-TSC autistic probands on the Social and Communication domains of the Autism Diagnostic Inventory (ADI) (Le Couteur et al., 1989), but show fewer Repetitive Rituals. There are more male TSC probands with autism than female, despite an equal sex ratio among TSC probands. The TSC probands with autism have significantly more seizures and mental retardation than those without autism; however, the extent and etiology of associations require further study. Our preliminary findings suggest that a fruitful approach for delineating genetic influences in autism may come from further investigation of possible mechanisms underlying the association of autism and TSC.


Remediating the thinking of pupils with autism: principles into practice. We take previously developed principles of a problem-solving approach to teaching pupils with (Jordan & Powell, 1990a, 1990b, 1991), and analyze their application within the normal teaching routine of a specialist school for such pupils. We note the kinds of pedagogical judgment made, and the structures needed by individual pupils to enable them to function as problem solvers. We identify reflection as a key factor in enhancing the potential of pupils as learners and discuss ways of increasing pupils' awareness of their own ways of handling learning situations. The study is set against the background of issues concerned with possibilities of developing a 'theory of mind' in pupils with autism.


Urinary cortisol circadian rhythm in a group of high-functioning children with autism. Previous research has suggested that there may be dysfunction in the control of the hypothalamic-pituitary-adrenal axis in autistic children. Both an abnormal cortisol circadian rhythm and failure to suppress cortisol secretion in response to dexamethasone have been reported. This study investigated the basal urinary cortisol circadian rhythm in a group of high-functioning children with autism and matched controls. No evidence was found for abnormal temporal placement of the circadian rhythm in the autistic group. There was a tendency towards cortisol hypersecretion during the day, predominantly in those autistic children who were integrated into the normal school system. While the temporal parameters of the cortisol circadian rhythm in these children with autism were probably normal, the tendency towards cortisol hypersecretion may indicate an environmental stress response in this group.


Prevalence and correlates of the premenstrual syndrome in adolescence. In a longitudinal study of their health and development, 384 15-year-old females reported their experience of symptoms indicative of premenstrual syndrome (PMS). The prevalence of these symptoms is reported and a group of adolescents is identified with the syndrome (14%). PMS was associated with current self-reported anxiety, inattention, and poor health. Preadolescent self-report and maternal ratings of physical and mental health did not significantly predict adolescent PMS. The results suggest that the experience of PMS in adolescence may be mediated by perceived health status; the roles of mental health and maternal influence in the development of adolescent PMS may be minimal.


Sex differences in the interaction between temperament and parenting. Temperament and parent-child relationships were measured in a random sample of 776 children followed over a 10-year period. The goal was to determine whether temperament evolves differently for boys versus for girls, and if so, whether parenting influences gender-specific development. Gender-specific parenting effects on the evolution of difficult temperament were found: low father-daughter closeness, and high mother-son punishment and control led to an increase in difficult temperament, whereas comparable father-son and mother-daughter effects were not present. A possible explanation for these findings is proposed. The contribution of these findings to understanding biology-environment interactions in causing sex differences in development is discussed.


Psychiatric comorbidity in treatment-seeking anorexics and bulimics. Current and lifetime psychiatric diagnoses were compared in 229 female patients seeking treatment for current episodes of anorexia nervosa (N = 41), bulimia nervosa (N = 98) and mixed anorexia nervosa and Schizophrenia-Lifetime Version, which was modified to include a section for DSM-III-R eating disorders, the Longitudinal Interval Follow-up Evaluation, and the Structured Interview for DSM-III Personality Disorders. Seventy-three percent of the anorexia nervosa subjects, 60% of the bulimia nervosa subjects, and 82% of the mixed anorexia nervosa and bulimia nervosa subjects had a current comorbid Axis I diagnosis. Major depression was the most commonly diagnosed comorbid disorder. Low rates of alcohol and substances abuse disorder were diagnosed, and personality disorder occurred in a minority of the sample. The subjects with mixed disorder manifested a higher lifetime prevalence of kleptomania than either the anorexics or the bulimics. High levels of comorbidity were noted across the eating disorder samples. Mixed disorder subjects manifested the most comorbid psychopathology and especially warrant further study.


Anorexia nervosa in 51 Swedish adolescents: premorbid problems and comorbidity. Fifty-one teenage cases with anorexia nervosa (AN) were compared with 51 age-, sex-, and school-matched cases with respect to premorbid developmental, physical, and psychiatric problems and comorbidity at the time of examination. Almost half of the AN group consisted of the total population of AN cases in one birth cohort. There were more premorbid personality problems in the AN group. Obsessive compulsive problems were very common in this group, as was undue concern about physical appearance. Depressive symptoms during the course of the eating disorder were almost universal in the AN group, but it did not appear that such symptoms had preceded the eating disorder. It seems that there may be a number of subgroups with AN and that the majority of these can be better understood in the light of factors intrinsic to the patients themselves rather than in the context of deviant family interaction.


Personality dimensions in eating disorders and their relevance for subtyping. Personality dimensions and psychopathological symptoms were assessed in 50 female patients hospitalized for the treatment of anorexia nervosa or bulimia nervosa and in 19 healthy female controls of similar age. Restricting anorexia nervosa patients, who had lost weight by consistently reducing their food intake, reported significantly greater self-control, inhibition of emotionality, and conscientiousness than controls or bulimia nervosa patients, before and after the data were corrected for depressive and eating pathology. Both nonbulimic and bulimic anorexia nervosa patients expressed stronger than normal conformance to moral and family values. On the impulsivity dimension, bulimia nervosa patients scored in the high normal range, whereas bulimic anorexia nervosa patients rated in the low normal range. The results suggest that a personality disposition toward overcontrol and reserve might constitute a risk factor for the restricting type of anorexia nervosa through fostering restrictive behavior toward food and avoidance of personal relationships.


Psychopathology in anorexia nervosa and depression. It has been hypothesized that anorexia nervosa is characterized by ineffectiveness, interpersonal distrust, and lack of interoceptive awareness. The Eating Disorder Inventory differentiates patients with anorexia nervosa from weight-preoccupied women on the basis of these subscales. To test further the specificity of these characteristics to anorexia nervosa, the Eating Disorder Inventory scores of 20 adolescent girls diagnosed with anorexia nervosa were compared with those of 21 girls with major depression and 21 girls with both anorexia nervosa and depression. Analyses of variance and discriminant function analysis revealed no significant differences in the scores of the three groups. By 2-year followup, subjects initially diagnosed with only anorexia nervosa showed less psychopathology than those with an additional diagnosis of depression. These findings raise further questions about the overlap between depression and anorexia nervosa and leave open the question of characteristic psychological features in anorexia nervosa.


The intellectual functioning of eating disorder patients. This study investigated the intellectual functioning of a large group of eating disorder patients to examine two previously reported findings: (1) this population exhibits above-average general intellectual skills; and (2) a specific pattern of strength in verbal abilities. Standard intellectual testing of 100 consecutive inpatient females with eating disorder diagnoses was performed. Results indicate intellectual performance conforming to a normal distribution with no specific pattern of strengths or weaknesses.


Cognitive-behavioral treatment of health-impairing food phobias in children. Three cases reports describe assessment and treatment of three boys (ages 6 to 8 years) hospitalized because of weight loss and malnutrition, caused by severe dietary restriction and/or refusal to eat solid food. Psychological, behavioral, and medical assessments indicated that the boys were of average intelligence, without other significant psychological or medical disorders. Their eating disturbances were conceptualized as phobic disorders maintained by family factors reinforcing the children's avoidant behaviors. Cognitive-behavioral treatment consisted of an individualized combination of contingency management, shaping, desensitization, relaxation training, education, and cognitive restructuring. Generalization and maintenance were promoted by training parents to implement treatment at home before discharge. Treatment positively affected overall caloric intake, weight gain, number of solid foods accepted, and incidence of emesis.


Aggression in preschoolers: its relation to socialization. The present article discusses developmental changes of aggression seen in preschool children and reports on an 18-month short-term prospective study of three preschool populations: a group referred for aggressive behavior problems, a normal control group, and a group of youngsters who had lived in violent homes, but showed no aggressive behaviors. Results indicate that the aggressive children, in comparison with the other two groups at age 4, showed a significant delay in their interpersonal awareness and perspective taking ability. However, although the aggressive children caught up with their peers in the course of the study period, there was no accompanying decrease in their aggressive behavior. The theoretical and clinical implications of these findings are discussed.


Psychiatric diagnoses of maltreated children: preliminary findings. The study sample consists of 96 children (61 maltreated, 35 controls) between 5 and 10 years of age. The two groups of subjects were compared on diagnoses as determined by the administration of the Diagnostic Interview for Children and Adolescents, Revised 6th Version (DICA-6-R) as well as clinical DSM-III-R diagnoses. Children who had suffered maltreatment exhibited significantly greater incidences of attention deficit hyperactivity disorder, oppositional disorder and post-traumatic stress disorder diagnoses than did controls, on both child and parent DICA interviews. The children's interviews revealed that maltreated children present with a significant incidence of psychotic symptomatology as well as personality and adjustment disorders. Conversely, conduct and mood disorders emerged as significant factors in the parent interviews, with the maltreated group showing significantly greater incidence of these diagnoses.


Maltreatment in psychiatrically hospitalized dually diagnosed adolescent substance abusers. The medical charts of 150 consecutive admissions of dually diagnosed substance abusing adolescents admitted to a psychiatric hospital were examined to determine the extent and characteristics of maltreatment. Results indicated that 61% of the sample experienced or had a history that warranted suspicion of past and/or current maltreatment. Physical abuse was the most frequent form of maltreatment, followed by sexual abuse and neglect. Thirty-seven percent of patients experienced multiple forms of maltreatment. Maltreated patients had significantly more hospitalizations than their nonmaltreated counterparts on the same unit. Moreover, the age of maltreated patients was significantly lower than nonmaltreated patients, perhaps indicating an earlier age of onset of psychiatric illness and/or substance abuse. Analyses of parental substance abuse and psychiatric history among the maltreated and nonmaltreated groups revealed no significant findings. Results are discussed in terms of the following: (1) increased risk of subsequent substance abuse in maltreated children; (2) need for systematic assessment of child maltreatment in psychological or psychiatric evaluations; and (3) importance of treatment to deal with abuse or neglect as part of a comprehensive substance abuse intervention strategy.


Sexually abused children at high risk for post-traumatic stress disorder. Ninety-two sexually abused children were studied using structured interviews and standardized instruments to determine the frequency of post-traumatic stress disorder (PTSD) and associated symptoms. Of these sexually abused children, 43.9% met DSM-III-R PTSD criteria; 53.8% of children abused by fathers, 42.4% abused by trusted adults, and 10% of those abused by strangers met criteria as opposed to none of the children abused by an older child. No relationship was observed between the time lapsed since last abusive episode and the presence of PTSD. Many children not meeting full criteria exhibited partial PTSD symptoms. Only one standardized instrument (Child Behavior Checklist) detected group differences with PTSD children exhibiting more symptoms. This study replicates an earlier pilot study and underscores the need for further PTSD research.


Child sexual abuse of Asians compared with other populations. This retrospective chart review study of a child sexual abuse clinic compared a consecutive sample of substantiated sexual abuse cases of Asian victims with random samples of black, white, and Hispanic victims. The findings suggest that there are clinically relevant differences between Asians and the other three populations. Asian victims showed a distinct demographic profile, suffered less physically invasive forms of abuse, were more likely to express suicidality, less likely to display anger and sexual acting out, and had less supportive primary caretakers than non-Asians. Awareness of such ethnic differences will help clinicians better evaluate and treat minority victims.


The failure of a school-based child sexual abuse prevention program. Structured interviews were administered to 22 children, ranging in age from 6 to 10 years old, who did not disclose long-term sexual abuse by an auxiliary school employee, despite having been exposed to a school-based child sexual abuse prevention program. The results are presented in the context of a review of existing literature on school-based child sexual abuse prevention programs. Results point to the ineffectiveness of brief, single presentation, prevention efforts not geared to specific developmental levels of the audience, the need to explore the impact of the variable of group versus individual victimization on disclosure, and the need for further study of sexually victimized children who received prevention programming with the addition of a control group sample.


Child and family factors that ameliorate risk between 4 and 13 years of age. Protective processes in at-risk children between 4 and 13 years of age were examined in a longitudinal study. A multiple risk index was used at 4 years to identify 50 high-risk children and 102 who were at low risk. Cognitive and social-emotional status were measured at each time point. The following indicators of protective processes were related to positive change in cognitive and/or social-emotional function in the high-risk children between 4 and 13 years: mother-child interaction; child perceived competence, locus of control, life events, and social support; and maternal parenting values, social support, depression, and expressed emotion. Many of these factors were also related to improvement in the low-risk children. Some variables showed an interaction effect, where impact was substantially higher in the high-risk group compared with the low-risk group. The utility of multiple risk constructs and process oriented approaches to protective factors are discussed.


Interviews with children who experienced major life stress: family and child attributes that predict resilient outcomes. Demographically comparable groups of children exposed to major life-stress, with stress resilient (SR) and stress affected (SA) outcomes at ages 10 to 12, were interviewed to assess perceptions of their caregiving environments, peer relationships, and themselves. SR children compared with SA children reported more: (1) positive relationships with primary caregivers, (2) stable family environments, (3) inductive and consistent family discipline practices, and (4) positive expectations for their futures. SR girls viewed their mothers as more nurturing than did SA girls. Perceptions of fathers, quality of peer relationships, and global self-concept did not differentiate the groups. A discriminant function analysis identified four variables that correctly classified 74% of the subjects as SR or SA. Findings support the view that caregiver-child relationships play a key role in moderating children's developmental outcomes under conditions of high stress.


A risk profile predicting psychological distress in Vietnamese Amerasian youth. The relationship between risk factors and psychological distress was examined in 161 Vietnamese Amerasian youth. Background factors such as a history of missing school, frequent hospitalizations, and previous refugee camp experience distinguished those with higher levels of anxiety and depression. This study provides support for attempts to link specific risk factors with increased levels of psychological distress in immigrant populations. Confirmation of the predictive power of these risk factors awaits completion of a longitudinal study following the Ameriasians as they resettle in the United States.


Outcome, prognosis, and risk in a longitudinal follow-up study. This study reports the results of a 4-year follow-up of a community sample of children who were ages 4 to 12 in 1983 at the first wave of data collection. Results on outcomes revealed that conduct disorder showed the greatest stability especially from late childhood to early adolescence. In multivariate analyses, both family dysfunction and problems getting along with others significantly predicted the persistence of one or more psychiatric disorders 4 years later, and low income predicted one or more psychiatric disorders among children free of disorder 4 years earlier. The implications of the results for the child psychiatric field, especially prevention, are discussed.


Six-year developmental course of internalizing and externalizing problem behaviors. The 6-year developmental course of parent-reported problem behavior in an epidemiological sample of 936 children assessed with the Child Behavior Checklist at 2-year intervals was determined. Children who were scored in the deviant range of the total problem score at time 1 were nine times more likely to be scored deviant 6 years later than were children who were not deviant at time 1 (odds ratio 9.0). Of the deviant children at time 1, 33% were deviant at time 4. There was no difference in the persistence of externalizing versus internalizing problems. This underscores the notion that internalizing problems should not be disregarded. Although this study demonstrated moderate stability of problem behaviors across a 6-year interval, children's problem behaviors should not be regarded as static. Many children showed changes in their level of functioning across time. However, extreme changes were the exception rather than the rule.


Three-year course of behavioral/emotional problems in a national sample of 4- to 16-year-olds: I. Agreement among informants. Quantitative and categorical indices of psychopathology are reported for a nationally representative longitudinal sample assessed via eight empirically derived cross-informants syndromes, internalizing, externalizing, and total problems. Results showed medium to large stabilities for parents' ratings during a 3-year interval on all comparable scales. Predictive correlations between time 1 parents' ratings and time 2 teacher and self-ratings were weaker than parent-to-parent correlations. Classification of children as deviant showed weaker predictive relations than did quantitative scores. Odds ratios showed that children classified as deviant by parents' time 1 ratings were much more likely to be deviant at time 2 on corresponding parent, teacher, and self-ratings than were children initially classified as nondeviant.


Three-year course of behavioral/emotional problems in a national sample of 4- to 16-year-olds: II. Predictors of syndromes. This study examined relations between parents' ratings of children's behavioral/emotional problems, family variables, and stressful experiences as predictors of 3-year outcomes in a nationally representative sample of American children. Outcomes were measured by time 2 parent, teacher, and self ratings on eight empirically derived cross-informant syndromes. Path analyses indicated that parent ratings of each time 1 syndrome predicted parent ratings of the same time 2 syndrome. Family variables and intervening stressful experiences predicted parent and self ratings, but not teacher ratings of syndromes. The number of family members receiving mental health services was the family variable that predicted the most time 2 syndromes. Parent reports of stress predicted parent ratings of time 2 syndromes, whereas child reports of stress predicted self-ratings of time 2 syndromes.


Children's mental health service needs and utilization patterns in an urban community: an epidemiological assessment. To assess children's mental health service needs and utilization patterns for a state planning effort, a cross-sectional survey that sampled 822 children aged 6 to 11 of a metropolitan center was conducted. When reports of parents and teachers were combined, 38.5% of children were screened to be at risk of psychiatric disturbance. Only 11% of children at risk received treatment in mental health settings, fewer than in schools (37%) or medical settings (13%). The findings illustrate the importance of interagency collaboration and the need to consider reports of parents and teachers and different dimensions of psychopathology in future planning and research.


Communication deficits in childhood schizotypal personality disorder. This study examined the similarities and differences in the communication deficits of 13 schizotypal and 12 schizophrenic children matched by age and IQ. Like schizophrenic children, schizotypal children underutilize some discourse devices necessary for coherent speech and overutilize others. Schizotypal children, however, appear to display a more restricted range of discourse deficits than schizophrenic children. In addition, their discourse deficits do not appear to be associated with clinical measures of loose associations. The clinical implications and the potential use of discourse measures to differentiate schizophrenic and schizotypal children are discussed.


Schizophrenia with childhood onset: a phenomenological study of 38 cases. Thirty-eight hospitalized children, ages 5.7 to 11.11 years, diagnosed with schizophrenic disorder by DSM-III criteria, are characterized regarding age, sex, race, socioeconomic status, pre- and perinatal complications, electroencephalogram, intelligence quotient, and family history of major psychiatric disorder. Clinical course, including age at onset of general and psychotic psychiatric symptoms and initial diagnosis of schizophrenic disorder, presence of DSM-III symptoms, hospital course, and response to antipsychotics are reviewed.


Capgras syndrome in adolescence.

Capgras syndrome in adolescence. Capgras syndrome, the delusion of substitution, has rarely been reported in adolescents. The etiology is unknown, and intense controversy surrounds the debate over the relative importance of biological versus psychological factors. Presented here are two cases of Capgras syndrome in adolescents and a review of the relevant biological, neuropsychological, and psychodynamic literature. The authors suggest that the psychological processes underlying the Capgras delusion are mediated by neuroanatomical connections between various brain areas and hypothesize that the fundamental lesion in Capgras syndrome may be the patient's inability or failure to acknowledge the authenticity of a person they clearly recognize.


Detecting clustered microcalcifications in the female breast: secondary digitized images versus mammograms. We compared the detection of clustered microcalcifications by means of conventional mammograms and by means of secondary digitized images with a spatial resolution of 2048 x 1684 pixels and a contrast resolution of 12 bit. A Receiver Operating Characteristic (ROC) study was carried out using a cadaver breast showing phantom microcalcifications. A set of 100 mammograms was evaluated by two experienced senior radiologists. The ROC scores obtained with the digital images were 10% lower than those obtained with the conventional images. This difference however does not reach statistical significance. The use of a digital zoom function based on pixel duplication is also investigated. This zoom function does not produce a change in the diagnostic accuracy of the digital method. Attention is also paid to the advantages and disadvantages encountered by the radiologists when working on the digital viewing system. The most important drawback seems to be that it is considerably more time consuming than the conventional procedure, and this is especially due to the long loading time of the images and to the absence of window and level preselections.


Acute colonic pseudo-obstruction.

Acute colonic pseudo-obstruction. We present two cases of acute colonic pseudo-obstruction, one complicated with perforation. Orthopedic surgery was the pathogenetic factor in both cases. Recovery was successful in both patients after appropriate treatment. The importance of conventional X-ray techniques, and more specially the plain X-ray of the abdomen, is stressed regarding early diagnosis and follow-up.


Magnetic resonance imaging of extrapontine lesions in central pontine myelinolysis. A rare case of central pontine myelinolysis and associated extrapontine myelinolysis is presented. The MR findings confirmed the observations reported in recent papers.


Telangiectatic osteogenic sarcoma: an unusual presentation. The authors present a case of telangiectatic osteogenic sarcoma of unusual radiographic presentation. The lesion presents as a slow growing, rather "benign" tumor, while most osteosarcomas usually present as osteolytic lesions of which the radiological aspect allows the diagnosis of malignancy with certainty.


Peritoneal seeding of a cerebral malignant astrocytoma via a ventriculo-peritoneal shunt. Except for glioblastomas, metastases of astrocytomas and of intracerebral tumors are in general very rare. It is well known that the process of spreading can be provoked or accelerated by surgical procedures. The presented patient, with the initial diagnosis of grade III astrocytoma developed peritoneal metastases after placement of a ventriculo-peritoneal shunt.


Aneurysm of the extrahepatic portal vein associated with segmental portal hypertension and spontaneous porto-caval shunting through the inferior mesenteric vein. A case of a congenital aneurysm of the extrahepatic portal vein is reported. It was complicated by segmental portal hypertension of the territory of the inferior mesenteric vein, which was a pathway for spontaneous porto-caval shunting.


Elastofibroma dorsi: CT, MR and pathologic study in a new case. As reported before elastofibroma dorsi is a rare benign tumor of elastic connective tissue with typical clinical and suggestive radiological features. We evaluated the CT and MR characteristics of this periscapular lesion in a new case, before and after contrast enhancement, and tried to determine in how far the nature and extent of the tumor can be predicted.


MR imaging of tuberculous spondylitis.

MR imaging of tuberculous spondylitis. This case report describes a patient presenting with symptoms of progressive paresis of both legs. An X-ray of the thorax demonstrated an aspect consistent with miliary tuberculosis. Magnetic resonance imaging (MRI) of the thoracic spine revealed medullary compression. The patient underwent a laminectomy and the diagnosis of spinal epidural tuberculoma was made. The patient has been treated with isoniazid, rifampicin and pyrazinamide. After a period of six months, she made a complete recovery.


A conjugation procedure for Bdellovibrio bacteriovorus and its use to identify DNA sequences that enhance the plaque-forming ability of a spontaneous host-independent mutant. Wild-type bdellovibrios are obligate intraperiplasmic parasites of other gram-negative bacteria. However, spontaneous mutants that can be cultured in the absence of host cells occur at a frequency of 10(-6) to 10(-7). Such host-independent (H-I) mutants generally display diminished intraperiplasmic-growth capabilities and form plaques that are smaller and more turbid than those formed by wild-type strains on lawns of host cells. An analysis of the gene(s) responsible for the H-I phenotype should provide significant insight into the nature of Bdellovibrio host dependence. Toward this end, a conjugation procedure to transfer both IncQ and IncP vectors from Escherichia coli to Bdellovibrio bacteriovorus was developed. It was found that IncQ-type plasmids were capable of autonomous replication in B. bacteriovorus, while IncP derivatives were not. However, IncP plasmids could be maintained in B. bacteriovorus via homologous recombination through cloned B. bacteriovorus DNA sequences. It was also found that genomic libraries of wild-type B. bacteriovorus 109J DNA constructed in the IncP cosmid pVK100 were stably maintained in E. coli; those constructed in the IncQ cosmid pBM33 were unstable. Finally, we used the conjugation procedure and the B. bacteriovorus libraries to identify a 5.6-kb BamHI fragment of wild-type B. bacteriovorus DNA that significantly enhanced the plaque-forming ability of an H-I mutant, B. bacteriovorus BB5.


Identification of a Bdellovibrio bacteriovorus genetic locus, hit, associated with the host-independent phenotype. Bdellovibrios invade and grow within the periplasmic space of suitable gram-negative bacteria. Wild-type bdellovibrios are obligately dependent on host cells for growth, but spontaneous host-independent (H-I) mutants that grow axenically on standard rich culture media can be isolated. Such mutants generally retain the ability to grow intraperiplasmically, although the plaques that they produce on lawns of host cells are smaller and more turbid than those produced by wild-type bdellovibrios. Here, we identify the first genetic locus associated with the H-I phenotype: hit (host interaction). We show that three individual H-I mutants suffered mutations at the hit locus and that recombination of wild-type hit sequences into the genomes of the H-I mutants greatly enhanced their plaquing ability. DNA sequence analysis localized the hit mutation in each of the H-I mutants to a 135-bp region of the genome. Mutations at hit may not fully account for the H-I phenotype, however, as recombination of wild-type hit sequences into the genomes of the H-I mutants had little effect on the axenic-growth phenotype of the mutants. Possible explanations for this result and potential roles for the hit locus are discussed.


The Caulobacter crescentus flaFG region regulates synthesis and assembly of flagellin proteins encoded by two genetically unlinked gene clusters. At a specific time in the Caulobacter crescentus cell cycle, a single flagellar filament and multiple receptor sites for the swarmer-specific phage phi Cbk are assembled at one pole of the predivisional cell. One cluster of genes required for this morphogenesis, the flaYG region, includes the flgJKL genes, which encode structural proteins of the flagellar filament. These flagellin genes are flanked by genes required for filament assembly, the flaYE genes at one end and the flaF-flbT-flbA-flaG genes at the other. In this study, we characterized mutants carrying large chromosomal deletions within this region. Several of these strains are phi CbK resistant and produce a novel 22-kDa flagellin that is not assembled into flagella. Merodiploid strains containing either the entire flaFG region or individual fla transcription units from this region were constructed. These strains were used to correlate the presence or absence of specific gene products to changes in flagellin synthesis, filament assembly, or phage sensitivity. As a result of these studies, we were able to conclude that (i) the production of the 22-kDa flagellin results from the absence of the flbA and flaG gene products, which appear to be components of a flagellin-processing pathway common to the 25-, 27-, and 29-kDa flagellins; (ii) flbT negatively modulates the synthesis of the 27- and 25-kDa flagellins from two genetically unlinked gene clusters; (iii) flgL is the only flagellin gene able to encode the 27-kDa flagellin, and this flagellin appears to be required for the efficient assembly of the 25-kDa flagellins; (iv) flaF is required for filament assembly; and (v) phi CbK resistance results from the deletion of at least two genes in the flaFG region.


Two-stage control of an oxidative stress regulon: the Escherichia coli SoxR protein triggers redox-inducible expression of the soxS regulatory gene. Escherichia coli responds to the redox stress imposed by superoxide-generating agents such as paraquat by activating the synthesis of as many as 80 polypeptides. Expression of a key group of these inducible proteins is controlled at the transcriptional level by the soxRS locus (the soxRS regulon). A two-stage control system was hypothesized for soxRS, in which an intracellular redox signal would trigger the SoxR protein as a transcriptional activator of the soxS gene and the resulting increased levels of SoxS protein would activate transcription of the various soxRS regulon genes (B. Demple and C.F. Amábile Cuevas, Cell 67:837-839, 1990). We have constructed operon fusions of the E. coli lac genes to the soxS promoter to monitor soxS transcription. Expression from the soxS promoter is strongly inducible by paraquat in a manner strictly dependent on a functional soxR gene. Several other superoxide-generating agents also trigger soxR(+)-dependent soxS expression, and the inductions by paraquat and phenazine methosulfate were dependent on the presence of oxygen. Numerous other oxidative stress agents (H2O2, gamma rays, heat shock, etc.) failed to induce soxS, while aerobic growth of superoxide dismutase-deficient bacteria triggered soxR-dependent soxS expression. These results indicate a specific redox signal for soxS induction. A direct role for SoxR protein in the activation of the soxS gene is indicated by band-shift and DNase I footprinting experiments that demonstrate specific binding of the SoxR protein in cell extracts to the soxS promoter. The mode of SoxR binding to DNA appears to be similar to that of its homolog MerR in that the SoxR footprint spans the -10 to -35 region of the soxS promoter.


Melting during steady-state transcription of the rrnB P1 promoter in vivo and in vitro. The rRNA rrnB P1 promoter was probed with the single-strand-selective reagent potassium permanganate during steady-state transcription in vitro and in vivo. In both cases, a weak but significant level of permanganate sensitivity was observed, which was not changed by treatment with rifampin. In contrast, static studies showed that rifampin strongly affects the very high level signal associated with polymerases that have used ATP and CTP as initiating nucleotides. We infer that the permanganate sensitivity associated with steady-state transcription is due to polymerases that have not yet used ATP and CTP. The slow and regulated step during rrnB P1 transcription may be the use of the initiating nucleotides to catalyze stable opening of the promoter DNA.


Identification, sequence analysis, and expression of a Corynebacterium glutamicum gene cluster encoding the three glycolytic enzymes glyceraldehyde-3-phosphate dehydrogenase, 3-phosphoglycerate kinase, and triosephosphate isomerase. To investigate a possible chromosomal clustering of glycolytic enzyme genes in Corynebacterium glutamicum, a 6.4-kb DNA fragment located 5' adjacent to the structural phosphoenolpyruvate carboxylase (PEPCx) gene ppc was isolated. Sequence analysis of the ppc-proximal part of this fragment identified a cluster of three glycolytic genes, namely, the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene gap, the 3-phosphoglycerate kinase (PGK) gene pgk, and the triosephosphate isomerase (TPI) gene tpi. The four genes are organized in the order gap-pgk-tpi-ppc and are separated by 215 bp (gap and pgk), 78 bp (pgk and tpi), and 185 bp (tpi and ppc). The predicted gene product of gap consists of 336 amino acids (M(r) of 36,204), that of pgk consists of 403 amino acids (M(r) of 42,654), and that of tpi consists of 259 amino acids (M(r) of 27,198). The amino acid sequences of the three enzymes show up to 62% (GAPDH), 48% (PGK), and 44% (TPI) identity in comparison with respective enzymes from other organisms. The gap, pgk, tpi, and ppc genes were cloned into the C. glutamicum-Escherichia coli shuttle vector pEK0 and introduced into C. glutamicum. Relative to the wild type, the recombinant strains showed up to 20-fold-higher specific activities of the respective enzymes. On the basis of codon usage analysis of gap, pgk, tpi, and previously sequenced genes from C. glutamicum, a codon preference profile for this organism which differs significantly from those of E. coli and Bacillus subtilis is presented.


Transcription of the Bacillus subtilis sacX and sacY genes, encoding regulators of sucrose metabolism, is both inducible by sucrose and controlled by the DegS-DegU signalling system. The adjacent sacX and sacY genes are involved in sucrose induction of the Bacillus subtilis sacB gene by an antitermination mechanism. sacB, encoding the exoenzyme levansucrase, is also subject to regulation by the DegS-DegU signalling system. Using sacXY'-lacZ and sacX'-lacZ fusions, we show that the transcription of the sacX and sacY genes is both inducible by sucrose and regulated by DegU. sacX and sacY appear to constitute an operon, since the deletion of the sacX leader region abolished the expression of a sacXY'-lacZ fusion. The degU-dependent promoter was located by deletion analysis and reverse transcriptase mapping 300 nucleotides upstream from the sacX initiator codon. Sucrose induction of the sacX'-lacZ fusion requires either SacY or the homologous SacT antiterminator, which is involved in sucrose induction of the intracellular sucrase gene (sacPA operon). Sequence analysis of the sacX leader region revealed (20 nucleotides downstream from the transcription start site) a putative binding site for these regulators; however, no structure resembling a rho-independent terminator could be found overlapping this site, unlike the situation for sacPA and sacB. Deletion of a segment of the leader region located 100 nucleotides downstream from this site led to constitutive expression of the sacXY'-lacZ and sacX'-lacZ fusions. These results suggest that the mechanism of sucrose induction of sacXY is different from that of sacPA and sacB.


The NodD protein does not bind to the promoters of inducible nodulation genes in extracts of bacteroids of Rhizobium leguminosarum biovar viciae. In a previous study, we showed that in bacteroids, transcription of the inducible nod genes does not occur and expression of nodD is decreased by 65% (H. R. M. Schlaman, B. Horvath, E. Vijgenboom, R.J.H. Okker, and B. J. J. Lugtenberg, J. Bacteriol. 173:4277-4287, 1991). In the present study, we show, using gel retardation, that in crude extracts of bacteroids of Rhizobium leguminosarum biovar (bv.) viciae, NodD protein does not bind to the nodF, nodM, and nodO box and that it binds only weakly to the nodA box. Binding of NodD from bacteroids to nod box DNA could be restored by mild proteinase K treatment, indicating that NodD is present in bacteroids in an altered form or complex which prevents its binding to nod box DNA. In addition, a novel nodA box DNA-protein complex was found which is specific for the nodA promoter region. This novel complex was formed neither with material from cultured bacterial cells nor with an extract from uninfected roots, and it did not contain NodD but another protein. These results are consistent with the hypothesis that the protein present in the novel retardation complex acts as a transcriptional repressor causing the decreased nodD expression in bacteroids. Such a repressor also explains the lack of nodABCIJ transcription despite the weak NodD binding to the nodA box.


Mutations that impair swarming motility in Serratia marcescens 274 include but are not limited to those affecting chemotaxis or flagellar function. Serratia marcescens exists in two cell forms and displays two kinds of motility depending on the type of growth surface encountered (L. Alberti and R. M. Harshey, J. Bacteriol. 172:4322-4328, 1990). In liquid medium, the bacteria are short rods with few flagella and show classical swimming behavior. Upon growth on a solid surface (0.7 to 0.85% agar), they differentiate into elongated, multinucleate, copiously flagellated forms that swarm over the agar surface. The flagella of swimmer and swarmer cells are composed of the same flagellin protein. We show in this study that disruption of hag, the gene encoding flagellin, abolishes both swimming and swarming motility. We have used transposon mini-Mu lac kan to isolate mutants of S. marcescens defective in both kinds of motility. Of the 155 mutants obtained, all Fla- mutants (lacking flagella) and Mot- mutants (paralyzed flagella) were defective for both swimming and swarming, as expected. All Che- mutants (chemotaxis defective) were also defective for swarming, suggesting that an intact chemotaxis system is essential for swarming. About one-third of the mutants were specifically affected only in swarming. Of this class, a large majority showed active "swarming motility" when viewed through the microscope (analogous to the active "swimming motility" of Che- mutants) but failed to show significant movement away from the site of initial inoculation on a macroscopic scale. These results suggest that bacteria swarming on a solid surface require many genes in addition to those required for chemotaxis and flagellar function, which extend the swarming movement outward. We also show in this study that nonflagellate S. marcescens is capable of spreading rapidly on low-agar media.


Bacteriophage P1 gene 10 is expressed from a promoter-operator sequence controlled by C1 and Bof proteins. Gene 10 of bacteriophage P1 encodes a regulatory function required for the activation of P1 late promoter sequences. In this report cis and trans regulatory functions involved in the transcriptional control of gene 10 are identified. Plasmid-borne fusions of gene 10 to the indicator gene lacZ were constructed to monitor expression from the gene 10 promoter. Production of gp10-LacZ fusion protein became measurable at about 15 min after prophage induction, whereas no expression was observed during lysogenic growth. The activity of an Escherichia coli-like promoter, Pr94, upstream of gene 10, was confirmed by mapping the initiation site of transcription in primer extension reactions. Two phage-encoded proteins cooperate in the trans regulation of transcription from Pr94: C1 repressor and Bof modulator. Both proteins are necessary for complete repression of gene 10 expression during lysogeny. Under conditions that did not ensure repression by C1 and Bof, the expression of gp10-LacZ fusion proteins from Pr94 interfered with transformation efficiency and cell viability. Results of in vitro DNA-binding studies confirmed that C1 binds specifically to an operator sequence, Op94, which overlaps the -35 region of Pr94. Although Bof alone does not bind to DNA, together with C1 it increases the efficiency of the repressor-operator interaction. These results are in line with the idea that gp10 plays the role of mediator between early and late gene transcription during lytic growth of bacteriophage P1.


The proper ratio of FtsZ to FtsA is required for cell division to occur in Escherichia coli. Interactions among cell division genes in Escherichia coli were investigated by examining the effect on cell division of increasing the expression of the ftsZ, ftsA, or ftsQ genes. We determined that cell division was quite sensitive to the levels of FtsZ and FtsA but much less so to FtsQ. Inhibition of cell division due to an increase in FtsZ could be suppressed by an increase in FtsA. Inhibition of cell division due to increased FtsA could be suppressed by an increase in FtsZ. In addition, although wild-type strains were relatively insensitive to overexpression of ftsQ, we observed that cell division was sensitized to ftsQ overexpression in ftsI, ftsA, and ftsZ mutants. Among these, the ftsI mutant was the most sensitive. These results suggest that these gene products may interact and that the proper ratio of FtsZ to FtsA is critical for cell division to occur.


Nucleotide and deduced amino acid sequences of the lacR, lacABCD, and lacFE genes encoding the repressor, tagatose 6-phosphate gene cluster, and sugar-specific phosphotransferase system components of the lactose operon of Streptococcus mutans. The complete nucleotide sequences of lacRABCDF and partial nucleotide sequence of lacE from the lactose operon of Streptococcus mutans are presented. Comparison of the streptococcal lac determinants with those of Staphylococcus aureus and Lactococcus lactis indicate exceptional protein and nucleotide identity. The deduced polypeptides also demonstrate significant, but lower, sequence similarity with the corresponding lactose proteins of Lactobacillus casei. Additionally, LacR has sequence homology with the repressor (DeoR) of the Escherichia coli deoxyribonucleotide operon, while LacC is similar to phosphokinases (FruK and PfkB) from E. coli. The primary translation products of the lacRABCDFE genes are polypeptides of 251 (M(r) 28,713), 142 (M(r) 15,610), 171 (M(r) 18,950), 310 (M(r) 33,368), 325 (M(r) 36,495), 104 (M(r) 11,401), and 123 (NH2-terminal) amino acids, respectively. As inferred from their direct homology to the staphylococcal lac genes, these determinants would encode the repressor of the streptococcal lactose operon (LacR), galactose-6-phosphate isomerase (LacA and LacB), tagatose-6-phosphate kinase (LacC), tagatose-1,6-bisphosphate aldolase (LacD), and the sugar-specific components enzyme III-lactose (LacF) and enzyme II-lactose (LacE) of the S. mutans phosphoenolpyruvate-dependent phosphotransferase system. The nucleotide sequence encompassing the S. mutans lac promoter appears to contain repeat elements analogous to those of S. aureus, suggesting that repression and catabolite repression of the lactose operons may be similar in these organisms.


Structure, function, and fate of the BlaR signal transducer involved in induction of beta-lactamase in Bacillus licheniformis. The membrane-spanning protein BlaR is essential for the induction of beta-lactamase in Bacillus licheniformis. Its nature and location were confirmed by the use of an antiserum specific for its carboxy-terminal penicillin sensor, its function was studied by genetic dissection, and the structure of the penicillin sensor was derived from hydrophobic cluster analysis of the amino acid sequence by using, as a reference, the class A beta-lactamases with known three-dimensional structures. During the first 2 h after the addition of the beta-lactam inducer, full-size BlaR, bound to the plasma membrane, is produced, and then beta-lactamase is produced. By 2 h after induction, BlaR is present in various (membrane-bound and cytosolic) forms, and there is a gradual decrease in beta-lactamase production. The penicillin sensors of BlaR and the class D beta-lactamases show strong similarities in primary structures. They appear to have the same basic spatial disposition of secondary structures as that of the class A beta-lactamases, except that they lack several alpha helices and, therefore, have a partially uncovered five-stranded beta sheet and a more readily accessible active site. Alterations of BlaR affecting conserved secondary structures of the penicillin sensor and specific sites of the transducer annihilate beta-lactamase inducibility.


In vitro activation of dinitrogenase reductase from the cyanobacterium Anabaena variabilis (ATCC 29413). Nitrogenase of the heterocystous cyanobacterium Anabaena variabilis was inactivated in vivo (S. Reich, H. Almon, and P. Böger, FEMS Microbiol. Lett. 34:53-56, 1986). Partially purified and modified (inactivated) dinitrogenase reductase (Fe-protein) of such cells was reactivated by isolated membrane fractions of A. variabilis or of Rhodospirillum rubrum, and acetylene reduction was measured. Reactivation requires ATP, Mg2+, and Mn2+. The activating principle is localized in the heterocyst and was found effective only when prepared from cells exhibiting active nitrogenase. It also restores the activity of modified Fe-protein from R. rubrum.


Functional replacement of genes for individual polyketide synthase components in Streptomyces coelicolor A3(2) by heterologous genes from a different polyketide pathway. Streptomyces coelicolor A3(2) and Streptomyces violaceoruber Tü22 produce the antibiotics actinorhodin and granaticin, respectively. Both the aglycone of granaticin and the half-molecule of actinorhodin are derived from one acetyl coenzyme A starter unit and seven malonyl coenzyme A extender units via the polyketide pathway to produce benzoisochromane quinone moieties with identical structures (except for the stereochemistry at two chiral centers). In S. coelicolor and S. violaceoruber, the type II polyketide synthase (PKS) is encoded by clusters of five and six genes, respectively. We complemented a series of S. coelicolor mutants (act) defective in different components of the PKS (actI for carbon chain assembly, actIII for ketoreduction, and actVII for cyclization-dehydration) by the corresponding genes (gra) from S. violaceoruber introduced in trans on low-copy-number plasmids. This procedure showed that four of the act PKS components could be replaced by a heterologous gra protein to give a functional PKS. The analysis also served to identify which of three candidate open reading frames (ORFs) in the actI region had been altered in each of a set of 13 actI mutants. It also proved that actI-ORF2 (whose putative protein product shows overall similarity to the beta-ketoacyl synthase encoded by actI-ORF1 but whose function is unclear) is essential for PKS function. Mutations in each of the four complemented act genes (actI-ORF1, actI-ORF2, actIII, and actVII) were cloned and sequenced, revealing a nonsense or frameshift mutation in each mutant.


Selective synthesis and labeling of the polysialic acid capsule in Escherichia coli K1 strains with mutations in nanA and neuB. The enzymes required for polysialic acid capsule synthesis in Escherichia coli K1 are encoded by region 2 neu genes of the multigenic kps cluster. To facilitate analysis of capsule synthesis and translocation, an E. coli K1 strain with mutations in nanA and neuB, affecting sialic acid degradation and synthesis, respectively, was constructed by transduction. The acapsular phenotype of the mutant was corrected in vivo by exogenous addition of sialic acid. By blocking sialic acid degradation, the nanA mutation allows intracellular metabolite accumulation, while the neuB mutation prevents dilution by the endogenous sialic acid pool and allows capsule synthesis to be controlled experimentally by the exogenous addition of sialic acid to the growth medium. Complementation was detected by bacteriophage K1F adsorption or infectivity assays. Polysialic acid translocation was observed within 2 min after addition of sialic acid to the growth medium, demonstrating the rapidity in vivo of sialic acid transport, activation, and polymerization and translocation of polysaccharide to the cell surface. Phage adsorption was not inhibited by chloramphenicol, demonstrating that de novo protein synthesis was not required for polysialic acid synthesis or translocation at 37 degrees C. Exogenous radiolabeled sialic acid was incorporated exclusively into capsular polysaccharide. The polymeric nature of the labeled capsular material was confirmed by gel permeation chromatography and susceptibility of sialyl polymers to K1F endo-N-acylneuraminidase. The ability to experimentally manipulate capsule expression provides new approaches for investigating polysialic acid synthesis and membrane translocation mechanisms.


A three-start helical sheath on the flagellar filament of Caulobacter crescentus. An unusual feature in preparations of the Caulobacter crescentus flagellar filaments is that some filaments are surrounded by a set of three windings that form a sheath. We provide evidence that the sheath is composed of subunits having a molecular mass of 24,000 Da. We suggest that the sheath could be composed of protofilaments of flagellin wound around the filament.