Effect of T-2 toxin on egg production and hatchability in laying hens.

The effect of diets containing different levels of T-2 toxin on egg production and hatchability was studied in a four-week experiment using 100 laying hens of the SSL hybrid line and 10 cocks divided into 10 groups. Another aim of the experiment was to investigate how effectively the increased dietary vitamin E content neutralized the adverse effects of T-2 toxin. The diet of the control group (C) contained no mycotoxin, while those of the experimental groups included the following levels of T-2 toxin: groups 1, 2 and 3: 1 mg/kg, groups 4, 5 and 6: 5 mg/kg; groups 7, 8 and 9: 10 mg/kg. Vitamin E was added to the diet of groups C, 1, 4 and 7 at a rate of 50 mg/kg while to that of groups 2, 5 and 8 at a rate of 100 mg/kg. To the diet of groups 3, 6 and 9 no vitamin E was added. Contamination of the diet with T-2 toxin markedly decreased egg production and impaired hatchability. The production decrease was proportional to the T-2 toxin concentration of the diet. Increased dietary vitamin E concentration exerted no influence on egg production. However, during the first week of the experiment it significantly (P < 0.01) decreased the number of infertile eggs and significantly (P < 0.01) improved the hatching percentage. Dietary vitamin E concentration was in positive correlation with the hatching percentage; this correlation was rather close (r = 0.74) in the first week of the experiment.


Further monogeneans from Iranian freshwater fishes.

Thirteen Dactylogyrus, 1 Dogelius and 1 Tetraonchus species are first recorded on Iranian fishes. Of them, twelve Dactylogyrus species and Tetraonchus monenteron are identified with known species. Dogelius persicus sp. n. from Barbus sharpeyi, Barbus grypus and Carassobarbus luteus, as well as Dactylogyrus holciki from Chalcalburnus mossulensis and C. chalcoides are described as new species. Besides the first record of the above monogeneans, new host records are given to some known species.


Demonstration of Clostridium septicum infection in a goose flock.

Clostridium septicum infection causing 5.0 to 5.2% mortality is reported for the first time in the literature from six-week-old growing geese in three flocks comprising 5,200, 5,500 and 5,900 geese, respectively. The affected birds exhibited weakness, uncoordinated movement, ataxia and, frequently, oblique position of the head and neck (torticollis) as well as signs indicative of dysequilibrium. The affected birds died within 18-24 h. Gross pathological examination revealed anaemia, hepatitis with map-like necroses of irregular outline (Fig. 1), acute enteritis, pulmonary oedema and cardiac dilatation. Light and electron-microscopic examination showed that the sinusoids of the liver were markedly dilated (Fig. 2) and filled with serous exudate and gas (Figs 2 and 3), and the hepatocytes surrounding them exhibited severe oedema (Fig. 4). Among the hepatocytes, ciliated bacteria 7-10 mu in length and 1-3 mu in width, bounded by a well-defined cell wall and often showing signs of spore formation were observed (Figs 5 and 6). By bacteriological examination the pathogen was isolated, its properties were studied, and the clinical entity of malignant oedema was experimentally reproduced by intramuscular injection of guinea-pigs and rabbits. The applied antibiotic (oxytetracycline) and furazolidone therapy proved effective.


Studies on canine mammary tumours. I. Age, seasonal and breed distribution.

The incidence as well as age, seasonal and breed distribution of canine mammary tumours (n = 521) were studied at the Clinic of Obstetrics and Gynaecology of the University of Veterinary Science, Budapest, between 1985 and 1989. In 39 cases of mammary tumour, blood plasma oestradiol (E2) and progesterone (P) concentrations were also determined. Of all dogs referred to the clinics of the University in 1985, 0.7% had mammary tumour. On the average, 104 +/- 9.3 cases of mammary tumour were recorded at the Clinic of Obstetrics per year. This number did not increase after the Chernobyl atomic reactor catastrophe of 1986. The age distribution of canine mammary tumour found in this study shows good agreement with earlier data of the literature: mammary tumour showed the highest incidence in 10 years old dogs. The incidence of mammary tumour kept increasing with age until the 14th year of life (as expressed in per cent of animals of identical age). The number of mammary tumours was markedly higher in the spring (April-May) and autumn (September). This seasonality was demonstrable in 11 to 16 years old bitches, too. On the basis of the blood plasma E2 and P profiles, 61.5% of the clinically anoestrous animals were found to be cycling. The strikingly high ratio of pulis among dogs with mammary cancer was suggestive of a breed disposition.


Studies on canine mammary tumours. II. Oestradiol and progesterone receptor binding capacity and histological type.

Tissue samples taken from the mammary gland of 42 dogs (age: 6 to 12 years) were examined. Thirty-eight samples showed neoplasia: 36 were epithelial while the remaining 2 proved to be connective tissue tumours. Thirty-four % of the neoplasms were new benign tumours (most frequently adenoma and fibroadenoma) and 66% were malignant ones (mainly adenocarcinoma). The oestrogen receptor (ER) and progesterone receptor (PR) binding capacity was determined on 21 tissue samples using the method of EORTC (1980). The connective tissue tumours and non-tumourous tissues contained no sexual steroid receptor. 71.4% of all tissue samples contained receptors. 61.9% of the samples was ER+, 42.8% was PR+, 33.3% contained both receptors, 28.6% was only ER+ and 9.5% only PR+. The average ER and PR binding capacity was 120.3 (5.0-622.8) and 266.7 (92.3-475.0) fmol/mg cytosol protein, respectively. No difference in receptor positivity was demonstrable between the benign and the malignant tumours. PR negativity accompanied by ER positivity was more common in the case of benign tumours. ER binding capacity tended to be correlated with age: this correlation could be described with a hyperboloid regression curve (r = -0.5931; 0.06 > p > 0.05).


Sulfonamide residues in eggs.

In two series of experiments lasting 3 days each, laying hens were medicated with sulfonamides via the drinking water. In the first experiment 8 laying hens were given sulfaquinoxaline (SQ) at a dose rate of 400 mg/l, while in the second trial 16 laying hens received a 3:5:5 sulfonamide mixture containing sulfaquinoxaline (SQ), sulfadimidine (SDI) and sulfamerazine (SMN), at a dose of 390 mg/l. According to the water consumption data, the hens' daily sulfonamide intake was 53.6 and 56.9 mg/kg body mass, respectively. Eggs laid during and in the first 10 days after the treatment were collected and assayed for sulfonamide residues by spectrophotometry. The detection limit of the method was 0.16 mg/l and the recovery percentage was between 70 and 80%. Sulfonamide was found to appear already in eggs laid after the first day of treatment. The absorption half-life of the drug was 0.4-0.6 day in the egg-white and 0.93-1.08 day in the egg-yolk. Peak drug level in the egg-white was measured on the last day of medication, while in the egg-yolk within 3 days after the end of treatment. The residue measured in the yolk was 13-16% of that found in the egg-white. Acetylated sulfonamide could be measured in the yolk for 3 days after the treatment: its level reached 15%. On the basis of the elimination rate, complete elimination of sulfonamides requires at least 5.2-7.4 days. Therefore, observance of the generally accepted withdrawal time of 10 days is indispensable.


Treatment of Class II high angle malocclusions with the Herbst appliance: a cephalometric investigation.

The purpose of this study was to examine the results of treatment of Class II malocclusions by using two different designs of the Herbst appliance. Cephalometric records from lateral headplates of 19 consecutively treated Class II cases were evaluated. The headplates were taken before and after the treatment stage in which the Herbst appliance was used. The patients were divided into two groups: the first group, normohypodivergent, was treated with the Herbst appliance attached to bands; the second group, hyperdivergent, was treated with the Herbst appliance attached to acrylic splints in which a high-pull headgear was also used. The results were compared between these groups and with a control group age-matched from Bolton standards to match the changes in the Herbst samples against what might be expected in case of normal growth during similar periods of time. The results of the investigation revealed the following: (1) 9 months of treatment resulted in Class I dental arch relationships in all 19 cases; (2) the Herbst appliance attached to bands did not significantly modify the vertical growth pattern of the normohypodivergent patients; and (3) in hyperdivergent patients, the use of a Herbst appliance attached to acrylic splints in conjunction with the use of a high-pull headgear allowed a better control of the vertical dimension, as assessed by the cephalometric parameters (FA, FMA, Go-Gn-SN). The clinician should be aware of the different dentofacial changes induced in the vertical plane by different designs of the Herbst appliance to better program treatment strategy.


Histologic investigation of the human pulp after thermodebonding of metal and ceramic brackets.

Twenty-five human permanent teeth scheduled for extraction for orthodontic reasons were used to study the effect of thermodebonding on the pulp tissue. One week before brackets were removed the teeth were bonded with either metal or ceramic brackets, with two alternative adhesives. For debonding, three different techniques were used: (1) debonding of ceramic brackets warmed up indirectly by resistance heating of a metallic bow applied to the bracket slot, (2) debonding of metal brackets warmed up directly by inductive heating of the bracket itself, and (3) debonding of ceramic brackets warmed up indirectly by inductive heating of metallic plier tips, applied to the mesial and distal bracket surfaces. Teeth with metal brackets removed without heat by squeezing the wings together served as a control group. The teeth were extracted 24 hours after debonding and subjected to a light microscopic study after histologic preparation and staining. In addition, the location of adhesive remnants was evaluated. While the thermodebonding of metal brackets worked properly and without any obvious pulp damage, there were problems related to the thermodebonding of ceramic brackets: (1) if more than one heating cycle was necessary, several teeth showed localized damage of the pulp with slight infiltration of inflammatory cells, (2) bracket fractures occurred frequently, and enamel damage could be shown, and (3) often with Transbond (Unitek/3M, Monrovia, Calif.) as the adhesive, more than one heating cycle was necessary for bracket removal, and thus patients complained about pain.


An in vitro study of the bond strength of two light-cured composites used in the direct bonding of orthodontic brackets to molars.

This study examines methods of improving the bond strengths of the light-activated composites, Heliosit-orthodontic, and Transbond. Begg brackets were bonded onto each of the four surfaces of 50 molar teeth that had been previously extracted. The bonding systems used were Right-on (R), Heliosit-orthodontic (H), Heliosit with a precured composite resin on the mesh (HPC), Heliosit with a precured intermediate bonding resin on the mesh (HPR), Transbond (T), and Transbond with a precured layer of resin on the mesh (TPC). The shear bond strengths were tested on a M5K tensile tester, crosshead speed 0.5 mm/min. After bracket removal, the enamel surface of the bonding site was examined and assessed with the adhesive remnant index (ARI). The shear bond strength in mean mPa +/- 1 SD was found to be significantly greater for HPC, HPR, and TPC than for H (P < 0.001). The ARI scores suggest that bond failure is associated more with the micromechanical bond with enamel for HPC and HPR. The results indicate that the chemical properties of the two light-activated adhesives were improved by precuring on the mesh base of the bracket before bonding.


The effects of infraocclusion: Part 3. Dental arch length and the midline.

The third and final article in this series examines the effect of infraocclusion on the midline of the mandibular dental arch. From clinical observation, a shift in the dental midline to the side affected by infraocclusion seemed very common, and this could be explained within the terms of the hypothesis proposed in the first article. A method was devised on a panoramic radiograph to define and to distinguish the anatomic (skeletal) midline and the dental midline. This confirmed the existence of a dental shift to the affected side. The hemiarch length of each side was measured on the film, from the distal of the second deciduous molar/second premolar to both constructed midlines, and was found to be longer on the affected side, confirming an abnormally distal position of the first molar on that side.


The effectiveness of differential moments in establishing and maintaining anchorage.

The purpose of the present study is to both clinically and cephalometrically investigate maximum and minimum anchorage control in four first premolar extraction cases, using the "differential moments (torque)" concept. Data were obtained from the pretreatment and posttreatment lateral cephalometric radiographs of 30 patients, 13 boys and 17 girls, who were treated exclusively with "differential torque" mechanics. Of the 30 patients selected, 18 were classified as having Angle Class I malocclusion (crowded and/or bimaxillary alveolar protrusion) and 12 as having Angle Class II, Division 1 malocclusion (crowded and/or severe overjet). The sample was divided into two groups, according to the severity of crowding. Subjects with 6.0 mm or more of crowding, in at least one quadrant per arch, were placed in the maximum anchorage group, suggesting the desirability of maintaining a relatively stable position of the anchor unit. Subjects with less than 6.0 mm of crowding per quadrant were categorized as moderate or minimum anchorage cases, indicating desirability of some intermediate degree of controlled movement of the anchor teeth. Comparison of the two groups in each malocclusion category revealed their comparability with respect to molar relationship and incisor overjet. The major finding of this study is the clinical effectiveness of differential moments as a means of controlling intraoral anchorage. It proves to be optimal and controllable for clinical purposes, regardless of the type of malocclusion or the severity of crowding.


Cephalometric pattern of Jewish East European adolescents with clinically acceptable occlusion.

Knowledge of the normal dentofacial patterns of various ethnic groups is important for clinical and research purposes. The objective of this study was to describe the dentofacial pattern of one Jewish ethnic group and to compare it with accepted standards for other white populations. Lateral cephalometric radiographs of 18 children of Jewish East European origin with clinically acceptable permanent occlusion, ages 11 to 13 years, were used. A computer-aided cephalometric analysis was performed, and the mean values and standard deviations for the various cephalometric variables were obtained. When compared with some classical standards, it was found that this ethnic group tended toward a mild skeletal Class II, a convex profile, and a more vertical direction of growth. These features appeared in persons selected on the basis of a clinically acceptable occlusion, suggesting the existence of dental compensations. Understanding these natural accommodations of the dentition to skeletal variations can be clinically useful when establishing treatment goals.


A comparative and correlational study of the cranial base in North American blacks.

The purpose of this investigation was to compare the cranial bases of blacks and whites in regard to length, angulation, and flexure, and to determine what proportion of the differences in facial measurements can be explained by the variability seen in the cranial base. Standardized cephalograms of 100 native-born North American black adults were traced, analyzed, and compared with white values. The measurements selected depicted dependency and independency from the cranial base. Mean differences between the races and the sexes were assessed with the Student's t test. Models of linear regression between the cranial base measurements and all other parameters were computed for both sexes and correlation coefficient values calculated. This study established that the length of the cranial base in North American blacks is significantly shorter from that of whites. A strong biologic relationship was demonstrated between the length of the cranial base of blacks and their denture bases, the palatal, and occlusal planes. The data suggest that most of the cephalometric differences between blacks and whites are not simply anatomic for measurements using sella nasion as their reference plane.


Change in mandibular growth direction by means of a Herbst appliance? A case report.

The orthodontic treatment of a skeletal Class II, Division 1 malocclusion related to the general growth rate of the patient is described. The female patient was observed from the late juvenile period of growth to the termination of growth. The patient had a vertical facial growth pattern during the initial treatment and observation period (2.5 years). During treatment with the Herbst appliance and the activator, the mandible grew forward. During treatment with the fixed appliance and the period of retention, the vertical growth pattern of the mandible returned.


Death due to superficial soft tissue injuries.

A series of deaths due to multiple superficial injuries is reported. These cases represented 5% of a consecutive homicide series in the Northern Territory of Australia. All cases were characterized by extensive superficial injuries, particularly involving soft tissue, which were present over much of the body including the face, head, arms, legs, and trunk. Upper-limb fractures were present in some cases, as were fractured ribs. The internal organs and tissues were pale, but there was either little or no organ damage. No significant volume of free blood was found in any of the body cavities. In one case, fat emboli were identified in moderate numbers in the lung and kidney. Death due to multiple superficial soft tissue injuries has not previously been characterized in the literature.


Morphologic variations in 180 cases of sudden infant death and 180 controls.

The incidence of morphologic variations (MVs) was investigated in 180 infants who died unexpectedly and suddenly and in 180 age-matched nonsuddenly deceased infants. The same person (G.M.) performed a full postmortem and histologic examination on all of the infants, none of whom had significant malformations. The test group (TG) consisted of 146 infants whose death was unexplained, whereas group 3 (G3) consisted of 34 infants with adequately determined causes of death. The principal findings in the control group were prematurity, inflammatory and metabolic diseases, tumors, and traumatic lesions. MVs were present in 62% of the TG infants, in 47% of the G3 children, and in 22% of the controls. The differences between the TG and G3 on the one hand and the controls on the other are statistically significant (p < 0.001 and 0.05, respectively). In the TG, anomalies were twice, dysplasias three times, and dysmorphisms four times as common as in controls; in G3, four times as many dysplasias and dystropics were found as in controls. In the TG, 23% of the MVs were multiple as compared with 9% in G3 and 5% in controls. The pattern of distribution was not confined to certain organs. Among the relative high percentage of dysplasias, the large number of neuroblastomas is striking.


Sudden infant death with anomalous origin of the left coronary artery.

Autopsy of a 3-month-old girl, an apparent case of sudden infant death syndrome, revealed anomalous origin of the left coronary artery from the right aortic sinus. Acute angulation of the left coronary artery along the aortic root, as well as a focal intramyocardial course within the ventricular septum, may have contributed to episodic luminal narrowing. Anomalous coronary origins of similar type have been associated with sudden death in children, teenagers, and young adults, but have not necessarily been associated with sudden death in older adults. Somewhat similar malformations have been reported in sudden infant death; two cases involved the left coronary artery and six involved the right.


Sudden and unexpected death of a 6-month-old baby with silent heart failure due to anomalous origin of the left coronary artery from the pulmonary artery.

A 6-month-old girl died suddenly without any previous symptoms of heart failure. Autopsy examination showed cardiomegaly (97 g) with a severely fibrotized myocardium. The left coronary artery was originating from the pulmonary artery. Histologically, the myocardium showed myocardial infarcts of different ages, as well as grossly thickened arterial branches due to increased flow in left-right shunt. We suggest that rare anomalies of the coronary arteries should be considered in the autopsies of suspected sudden infant death syndrome cases.


Fatal hypokalemic thyrotoxic periodic paralysis presenting as the sudden, unexplained death of a Cambodian refugee.

For the last decade, death investigators have been aware of an unexplained syndrome of sudden death occurring among young adult Southeast Asian refugees. Presented here is a rare instance of fatal hypokalemic periodic paralysis associated with thyrotoxicosis masquerading as the sudden, unexplained death of a Cambodian refugee. The usual features of this syndrome were present, including relatively occult thyrotoxicosis, paralysis upon awakening following a high-carbohydrate meal, and hypokalemia. This case illustrates the value of thorough background death investigation and also illustrates the potential of misinterpreting traditional folk medicine coin rubbing (Cao Gio) as signs of physical abuse.


Sudden death due to lymphoplasmacytic hypophysitis.

We report the case of a 37-year-old mentally retarded woman who died suddenly with premortem clinical signs of diabetes insipidus. At autopsy, her pituitary was infiltrated and destroyed by a lymphoplasmacytic infiltrate, affecting the posterior pituitary more severely than the anterior pituitary. Vitreous electrolytes showed a pattern of hypertonic dehydration, compatible with diabetes insipidus.


Sudden death in angiodysplasia of the gastroesophageal junction.

A 22-year-old Korean soldier, who had received blows to the neck and epigastrium from an officer 10 h earlier, suddenly died after massive hematemesis. He had been in relatively good health except for episodes of blood-tinged vomiting approximately 5 and 7 months prior to this event. Postmortem examination revealed angiodysplasia involving the gastroesophageal junction, and the stomach was distended with blood. No abnormal findings were present around the whole viscera, and the duodenum was free of blood. The pathologic significance of upper gastrointestinal angiodysplasia as a potential source of bleeding and a chronologic correlation between the trauma and bleeding are discussed.


Sudden death in children due to mesenteric defect and mesenteric cyst.

Two cases of sudden death in young female children due to small intestinal volvulus are reported, which involved a mesenteric defect and a mesenteric cyst. Death due to small intestinal volvulus is uncommon, especially when complicated by either a mesenteric defect or cyst.


An autopsy case of infant death due to heat stroke.

We report an autopsy case of infant death due to heat stroke. On a winter day, a 52-day-old female baby was placed under a Japanese electric foot warmer with a coverlet (kotatsu) on an electric carpet warmer in a heated room at home. After about 5 h, the mother noticed that the baby was unconscious and took her to a hospital. Spontaneous respiration, however, was already absent, and the pupils were dilated. The trunk was hot; body temperature was 41.3 degrees C. The skin of the whole body was dry. Autopsy revealed second-degree burn injuries on the left side of the face and the dorsum of the left hand. Numerous marked petechiae and ecchymoses were found in the thymus (capsule and parenchyma), pleurae (visceral and parietal), pericardial cavity (internal and external surfaces), epicardium, and beneath the serosa at the origin of the aorta. In addition, there was congestion in various organs, edema in the brain and lungs, and hemorrhage in the lungs. Histopathologically, macrophages without hemosiderin granules were present in the alveoli. When the heating conditions at the accident were reproduced experimentally, the temperature in the electric kotatsu warmer rose to 50-60 degrees C. Thus, we concluded that misuse of the electric kotatsu caused heat stroke in this infant.


Unusual intravascular hemolysis in a case of fatal hypothermia.

A 55-year-old man was discovered dead inside a deep freezer maintained at -40 degrees C. After consuming a large quantity of alcohol, the man had become trapped in the freezer approximately 11 h before his body was found. The body was still frozen at the time of autopsy, but subcutaneous dendriform vessel repletion phenomenon was observed on the upper and lower extremities. Although this intravascular hemolysis resembled that which develops during putrefaction, in this case it was thought to be due to pooling and freezing of blood in subcutaneous vessels. Contributory factors included alcohol ingestion, vasodilation following vasoconstriction, vasomotor paralysis, and red cell sludging. Hemolysis followed freezing of the blood. When such phenomena are observed in a corpse, exposure to extreme cold should be suspected.


The clinical problem of occult cardiac amyloidosis. Forensic implications.

A 68-year-old man with known coronary heart disease experienced rapidly progressive cardiac dysfunction and was found to have occult cardiac amyloidosis at autopsy. The amyloidosis was undiagnosed during life and initially at autopsy. Marked diffuse involvement of the intramural coronary arteries by amyloid deposits resulted in severe luminal compromise of numerous medium and small vessels. The myocardium proper was virtually spared from amyloid deposits. Amyloid-related coronary narrowing contributed to cardiac ischemia and sudden death. The significance of amyloid coronary disease in this patient relates primarily to the difficulty in considering the diagnosis when other reasons for cardiac signs and symptoms preexist. Also, the adverse effects of amyloid coronary disease may be profound without direct myocardial involvement.


Rupture of splenic artery aneurysm.

Three cases of death from splenic artery aneurysm rupture were encountered from 1988 to 1991 at the Philadelphia Medical Examiner's Office. In two cases, cocaine was detected in the blood and was believed to have precipitated the rupture. Toxicologic testing for cocaine should be performed in all cases of splenic artery aneurysm rupture and its presence should be interpreted properly as contributory rather than incidental to death.


Fatal hemothorax from mycotic celiac artery aneurysm.

We present two cases of ruptured mycotic aneurysms infected with Staphylococcus aureus. Each patient had hemoptysis and in each case there was hemothorax caused by a ruptured mycotic aneurysm of the celiac artery. In case 1, the pathogenesis was transient Staphylococcus aureus septicemia infecting an atherosclerotic plaque with subsequent aneurysm formation and rupture. In case 2, the septicemia arose from an infected knee. The presentation of a celiac artery aneurysm as hemoptysis and as the cause of hemothorax is rare.


Unusual death of a farmer.

A farmer was found dead, in a pool of blood on his farm. Evidence indicated that the farmer had dragged himself or been dragged from the stable to the point where his body was found. With the exception of abrasions in the face, there were no other signs of injury. An autopsy revealed a depressed fracture of the skull and showed a venous air embolism to be the cause of death. The medicolegal interpretation of the findings left no doubt that the farmer was killed by a cow.


Traumatic transection. An unusual fatal pedestrian injury.

Speed, alcohol, and pedestrian injuries constitute disturbing components of the spectrum of trauma in the developing world. The complete fatal transection of a pedestrian, at the level of the lower abdomen, by an oncoming automobile traveling at high speed is described. The upper torso was found inside the vehicle, whereas the lower torso was projected some distance ahead, onto the highway. An accident analysis, in order to ascertain the speed of the automobile, is demonstrated and the biodynamic mechanisms of this injury are discussed. The nature of this injury is compared with that of traumatic hemipelvectomy following which survival has been reported.


A retrospective analysis of alcohol in medicolegal postmortems over a period of five years.

Violence and violent death are everyday events in present-day South Africa. Although this phenomenon may be attributed in great part to the sociopolitical environment, the single most important underlying common factor is the presence of alcohol in both the perpetrators of violence and their victims. We retrospectively studied 948 cases of 2,980 medicolegal autopsies done over a 5-year period. We found that 52.5% of cases tested positively for alcohol, with blood alcohol concentration varying from 0.008 to 0.048 g% (mean = 0.18). Male patients were more common and more likely to be positive than female patients. Breakdown of the cases into various modes of death showed that homicides, vehicular accidents, and suicides predominated. The results are in agreement with earlier studies done locally and elsewhere.


Traumatic seromuscular rupture of intestine.

A vehicular accident victim sustained multiple transverse split-thickness intestinal lacerations. This rare and distinctive seatbelt injury results from the impact of intestinal loops against the abdominal restraint, whereby the rigid muscle coat ruptures, while the integrity of inner layers is preserved.


Drinking and driving in Singapore, 1987 to 1989.

Between 1987 and 1989 there were approximately 5,000 cases of fatal and injury-sustained road traffic accidents, of which 2.3-3.0% were alcohol related (blood alcohol levels greater than the legal limit of 80 mg% ethanol). The offenders of alcohol-related accidents are mostly Chinese (> 79%), male (> 98%), and more often 30-40 years old. The majority of the alcohol-related accidents (> 74%) took place between 8 P.M. and 4 A.M. in fine weather and light traffic. Rear-end, head-on, and side-on collisions comprised > 60% of all the alcohol-related accidents, and losing control of vehicles approximately 30%. Drunken driving cases for the same period that were not accidents showed a number of characteristics similar to those for accidents. In Singapore, motorcycle riders and pedestrians are more prone to road fatality than other road-user groups. International comparisons of road fatalities per 100,000 population gave Singapore one of the lowest accident rates (8.1-8.4) as compared with countries such as Australia, the United Kingdom, the United States, New Zealand, Canada, and Japan.


Perak, Malaysia, mass poisoning. Tale of the Nine Emperor Gods and rat tail noodles.

In October 1988, a series of food poisoning cases occurred in the State of Perak in Malaysia. Most of the victims were children. Ultimately 13 children between the ages of 2.5 and 11 years died. Epidemiological investigations showed that the probable source of the poison was Loh See Fun, a noodles in the shape of a rat's tail. All the deceased ate the noodles from one supplier. Clinical and pathological findings were similar in each case. Postmortem examination was performed in 11 cases. Toxicological examination on organs in 10 cases showed a high concentration of aflatoxin in tissues of the deceased. High levels of boric acid were excreted from most of the victims. Histological examination of the liver in these cases showed necrotic changes found in aflatoxin poisoning. Combination of the epidemiological, clinical, toxicological, and pathological findings pointed to the fact that there was a common toxin or toxins responsible for the deaths. These were thought to be a combination of boric acid and aflatoxin.


Homicide by starvation.

Homicide by starvation is a very rare occurrence, especially when the victim is ambulant. This paper presents a case where the death of the individual went undiscovered for more than 3 weeks. A successful conviction for murder ensued. The paper also discusses social and pathological problems associated with this crime.


An unusual case of gas embolism.

We present an unusual case that resulted from the wrongful connection of a high-pressure oxygen cylinder to a venous cannula. The case history and the autopsy findings are given and the mechanism of death is described.


Homicidal traumatic asphyxia associated with pebble impaction of the upper airway.

The news media tend to sensationalize murders involving multiple methods because of their inherent brutality. Similarly, when addressing a jury, prosecutors often emphasize the most grisly part of a murder to ensure a speedy conviction. This paper reports a case of a teenage boy who was murdered by the use of multiple methods of asphyxia. The methods of asphyxial death and the reconstruction of the sequence of events by the medical experts during the murder trial played an important role in the conviction and ultimate sentencing of the perpetrators.


Characteristics relating to ovarian cancer risk: collaborative analysis of 12 US case-control studies. I. Methods. Collaborative Ovarian Cancer Group.

Data from 12 US case-control studies of ovarian cancer, conducted during the period 1956-1986 and representing some 3,000 cases and 10,000 controls, were pooled and reanalyzed. Separate analyses were conducted for four subgroups of the pooled data: invasive epithelial ovarian cancers in white women; epithelial ovarian cancers of low malignant potential in white women, epithelial ovarian cancers in black women, and nonepithelial ovarian cancers. This paper gives a brief description of the participating studies and describes the methods used in the collaborative analysis.


Characteristics relating to ovarian cancer risk: collaborative analysis of 12 US case-control studies. II. Invasive epithelial ovarian cancers in white women. Collaborative Ovarian Cancer Group.

Data collected from 2,197 white ovarian cancer patients and 8,893 white controls in 12 US case-control studies conducted in the period 1956-1986 were used to evaluate the relation of invasive epithelial ovarian cancer to reproductive and menstrual characteristics, exogenous estrogen use, and prior pelvic surgeries. Clear trends of decreasing risk were evident with increasing number of pregnancies (regardless of outcome) and increasing duration of breast feeding and oral contraceptive use. Ovarian dysfunction leading to both infertility and malignancy is an unlikely explanation for these trends for several reasons: 1) The trends were evident even among the highly parous; 2) risk among nulliparous women did not vary by marital status or gravidity; and 3) risk among ever-married women showed little relation to length of longest pregnancy attempt or history of clinically diagnosed infertility. Risk was increased among women who had used fertility drugs and among women with long total duration of premenopausal sexual activity without birth control; these associations were particularly strong among the nulligravid. No consistent trends in risk were seen with age at menarche, age at menopause, or duration of estrogen replacement therapy. A history of tubal ligation or of hysterectomy with ovarian conservation was associated with reduced ovarian cancer risk. These observations suggest that pregnancy, breast feeding, and oral contraceptive use induce biological changes that protect against ovarian malignancy, that, at most, a small fraction of the excess ovarian cancer risk among nulliparous women is due to infertility, and that any increased risk associated with infertility may be due to the use of fertility drugs.


Characteristics relating to ovarian cancer risk: collaborative analysis of 12 US case-control studies. III. Epithelial tumors of low malignant potential in white women. Collaborative Ovarian Cancer Group.

Epithelial ovarian neoplasms of low malignant potential, also called borderline ovarian tumors, have various features of malignancy, but they do not invade the ovarian stroma. Women with these tumors usually are younger when diagnosed and have better prognoses than do women with invasive tumors. There have been few epidemiologic studies of borderline tumors, and it is unclear whether there are etiologic differences between the two types of tumor behavior. Combined data from nine case-control studies, conducted from 1974 to 1986 and representing 327 white women with tumors of low malignant potential and 4,144 white controls, were used to evaluate the relation between these tumors and personal characteristics related to invasive ovarian cancer. The risk profile for tumors of low malignant potential was found to be similar to that for invasive tumors, with two exceptions: Compared with that of invasive tumors, risk of borderline tumors was less clearly reduced among women who had used oral contraceptives and more clearly elevated among women with a history of infertility.


Characteristics relating to ovarian cancer risk: collaborative analysis of 12 US case-control studies. IV. The pathogenesis of epithelial ovarian cancer. Collaborative Ovarian Cancer Group.

Two hypotheses have been proposed to explain the reduced risk of epithelial ovarian cancer associated with pregnancy and oral contraceptive use. The first states that some sequelae of ovulation increase the likelihood of malignancy and that pregnancies and oral contraceptives protect by suppressing ovulation. The second hypothesis states that circulating levels of pituitary gonadotropins increase the risk of malignancy and that pregnancies and oral contraceptives protect by suppressing secretion of these hormones. The authors evaluate the two hypotheses in light of combined data from 12 United States case-control studies of epithelial ovarian cancer in white women conducted from 1956 to 1986. While a number of observations support both hypotheses, there are exceptions. Differential risk reduction associated with pregnancy and oral contraceptive use (pregnancy being the more effective in young women and the less effective in older women) conflicts with the first "ovulation" hypothesis, while reduced risk associated with breast feeding and absence of altered risk associated with estrogen replacement therapy conflicts with the second "gonadotropin" hypothesis. Several findings would not have been predicted by either hypothesis, e.g., only weak trends relate cancer risk to age at menarche, and, among older women, no clear trends relate risk to age at menopause. Odds ratio attenuation due to errors in reporting personal characteristics may be responsible for some of these inconsistencies. Multidisciplinary research is needed to clarify the etiologic roles of ovulation and gonadotropin stimulation, both of which may enhance carcinogenesis in the ovarian epithelium.


Increased risk of breast cancer with alcohol consumption in postmenopausal women.

The association between breast cancer incidence and alcohol consumption among postmenopausal women was examined in the Iowa Women's Health Study. In January 1986, a cohort of 41,837 postmenopausal women, aged 55-69 years, completed a questionnaire that included alcohol intake and other information. Through December 1989, 493 incident breast cancer cases were identified. Age-adjusted relative risks of consumption of less than 1.5, 1.5-4.9, 5.0-14.9, and 15.0 g or more of alcohol per day compared with abstention were 1.08, 1.10, 1.08, and 1.28, respectively (p for trend = 0.11). After controlling for age, body mass index, age at first livebirth, age at menarche, and family history of breast cancer, the relative risks were 1.18, 1.20, 1.25, and 1.46 (p for trend = 0.04). Multivariate modeling, using Cox proportional hazards regression, revealed a significant multiplicative interaction between alcohol intake and noncontraceptive estrogen use. The relative risks of breast cancer associated with average daily alcohol consumption of 5.0-14.9 and 15.0 g or more were 1.88 (95% confidence interval 1.30-2.72) and 1.83 (95% confidence interval 1.18-2.85), respectively, among ever-users of estrogen; no association between alcohol and breast cancer was observed among never-users of estrogen.


Cancer identification using a tumor registry versus death certificates in occupational cohort studies in the United States.

Studies of cancer incidences among occupational cohorts are rarely performed in the United States because of incomplete registration and a limited time period available for follow-up. This study used data from concurrent studies of cancer mortality and incidence among a cohort of 4,528 fire fighters and police officers employed by the cities of Seattle and Tacoma, Washington, between 1944 and 1979 to examine the relative advantages of tumor registry and death certificate information. As expected, an increased ability to study relatively common cancers with low fatality rates was demonstrated using incidence data. The most dramatic example was seen for bladder cancer. Twenty-four bladder cancers had been diagnosed among the study cohort between 1974 and 1989, whereas only two deaths were attributed to this malignancy. The standardized incidence ratio for bladder cancer was 1.05 (95% confidence interval 0.67-1.55), whereas the corresponding standardized mortality ratio was 0.46 (95% confidence interval 0.05-1.65). The observed relative risk estimates for rapidly fatal cancers were similar using the two sources of information, and no increase in precision was observed. Of 142 persons in the registry area who died of cancer during the study period, 20 (14%) had a different site listed on the death certificate than was identified by the registry. Approximately 7% of the potential person-years of follow-up were lost due to migration out of the registry area; loss to follow-up was greater among older and short-term workers, but did not exceed 13% of the person-years. Population-based tumor registries can be a useful resource in the investigation of occupational cancer in the United States, especially for the study of cancers with high survival rates.


Calcium intake and blood pressure in elderly women.

The authors studied the relative importance of calcium intake as a correlate of blood pressure in a cross-sectional analysis of 6,517 nonblack women aged > or = 65 years from Portland, Oregon; Minneapolis, Minnesota; Baltimore, Maryland; and the Monongahela Valley near Pittsburgh, Pennsylvania, who enrolled in the Study of Osteoporotic Fractures in 1986. Dietary calcium intake was measured by using a modified food frequency questionnaire. There were weak associations between total calcium intake and blood pressure, such that each 1,000 mg/day increase in calcium intake was associated with a 1.5 mmHg decrease in systolic blood pressure (95% confidence interval -2.2 to -0.8, p < 0.0001) and a 0.5 mmHg decrease in diastolic pressure (95% confidence interval -0.8 to -0.20, p < 0.004). After adjustment for confounding variables, total calcium intake continued to have a weak inverse association only with diastolic blood pressure. The multivariate models revealed several stronger independent risk factors for blood pressure, including age, body mass index, alcohol consumption, and level of education (all p < 0.01). The small size of the inverse association between calcium intake and blood pressure limits its biological importance in this population of elderly women.


Alcohol, smoking, coffee, and cirrhosis.

Since most heavy drinkers do not develop alcoholic cirrhosis, other causes or predisposing factors are probable. The authors studied traits of 128,934 adults who underwent health examinations at the Oakland and San Francisco, California, facilities of the Kaiser Permanente Medical Care Program from January 1978 to December 1985 in relation to subsequent hospitalization or death from cirrhosis of the liver. In analyses adjusted for nine covariates, past and current alcohol drinking were strongly related to cirrhosis risk, but usual choice of alcoholic beverage had no independent relation. Cigarette smoking was independently related to risk of alcoholic cirrhosis, with cigarette smokers of a pack or more per day at trebled risk compared with lifelong nonsmokers. Coffee drinking, but not tea drinking, was inversely related to alcoholic cirrhosis risk, with persons who drank four or more cups per day at one-fifth the risk of noncoffee drinkers. This inverse relation between coffee consumption and risk of alcoholic cirrhosis was consistent in many subsets, including persons free of gastrointestinal disease and those with 5 or more years before hospitalization or death. Cigarette smoking and coffee consumption were not consistently related to risk of hospitalization or death for nonalcoholic cirrhosis. These data could mean that cigarette smoking promotes alcoholic cirrhosis and that coffee drinking might be protective.


Maternal age as a risk factor for wheezing lower respiratory illnesses in the first year of life.

Postneonatal mortality due to respiratory illnesses is known to be inversely related to maternal age, but the possible role of young motherhood as a risk factor for respiratory morbidity in infants has not been thoroughly explored. The authors studied the incidence of lower respiratory tract illnesses during the first year of life, as ascertained by health plan pediatricians, in over 1,200 infants enrolled at birth between 1980 and 1984 in Tucson, Arizona. The incidence of wheezing lower respiratory tract illnesses increased significantly (p = 0.005) with decreasing maternal age, whereas the incidence of nonwheezing lower respiratory tract illness was independent of maternal age. A logistic regression was used to control for the effects of several known confounding factors. When compared with infants of mothers aged more than 30 years, adjusted odds ratios were 2.4 (95% confidence interval 1.8-3.1) for infants whose mothers were less than age 21 years (p < 0.0001), 1.8 (95% confidence interval 1.4-2.3) for infants whose mothers were aged 21-25 (p < 0.0001); and 1.4 (95% confidence interval 1.1-1.6) for infants whose mothers were aged 26-30 (p < 0.001). These results suggest that young motherhood is an important risk factor for wheezing lower respiratory tract illnesses during the first year of life. Both biological and social factors related to maternal age may explain these findings.


Five cross-sectional studies of grain elevator workers.

Five cross-sectional studies were conducted on grain workers in all the terminal elevators in British Columbia, Canada, at 3-year intervals from 1976 to 1988. Civic workers were studied in the same manner as a referent group. The studies consisted of questionnaires, spirometry using the same spirometers, allergy skin tests, and measurement of dust concentration by personal sampling. Although the dust concentration in the elevators was reduced progressively over the years, grain workers had more respiratory symptoms and lower lung function compared with the civic workers in each of the five cross-sectional studies. Exposure to grain dust was associated with significant reduction in forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) but not in maximal midexpiratory flow rate or FEV1/FVC, suggesting reduction in volume which may be due to lesions in the lung parenchyma or in the small airways. Cigarette smoking was associated with significant reduction in FEV1, maximal midexpiratory flow rate, and FEV1/FVC due to airflow obstruction, but had no influence on FVC. Workers who took part in all five surveys tended to be a "healthier" selected group, but the grain workers still had lower lung function compared with the civic workers. This study confirmed previous findings that grain dust has adverse effects on the lungs. Cross-sectional study of the grain elevator workers proved to be a consistent and useful method to evaluate occupational health hazards.


The importance of biopsychosocial factors in the development of duodenal ulcer in a cohort of middle-aged men.

This study prospectively evaluated psychosocial as well as biologic, behavioral, and demographic factors in the development of duodenal ulcer. Baseline data were collected in 1963 on 8,458 Israeli men over age 40 years who had no history of duodenal ulcer. The subjects were followed for 5 years, and 254 reported the development of radiographically proven duodenal ulcer. The average annual incidence was six per 1,000 subjects. Multivariable logistic regression analysis confirmed several previously reported risk factors: smoking (odds ratio (OR) = 1.64, 95% confidence interval (Cl) 1.25-2.16), greater age (60 years and over) (OR = 1.85, 95% Cl 1.25-2.74), lower salary (OR = 1.50, 95% Cl 1.14-1.96), and lower systolic blood pressure (less than 140 mmHg) (OR = 1.58, 95% Cl 1.16-2.15). In addition, logistic regression analysis revealed a significant association of duodenal ulcer incidence with preceding measures of family stress, emotional support, and coping style. These were: increased family problems (OR = 1.60, 95% Cl 1.19-2.16), low level of perceived love and support from subject's wife (OR = 2.06, 95% Cl 1.05-4.05), and restraining retaliation when hurt by coworkers (OR = 1.89, 95% Cl 1.19-3.00). This study confirms several previously reported risk factors and underlines the importance of stress, lack of social support, and coping style in the development of duodenal ulcer.


Clostridium perfringens outbreak associated with minestrone soup.

Clostridium perfringens food poisoning usually occurs after animal protein foods such as meat or poultry are consumed. In November 1990, an outbreak of gastrointestinal illness occurred among attendees at a conference of cake decorators held in Michigan. All 42 conference attendees were surveyed. Thirty-two of 42 (76%) attendees reported gastrointestinal symptoms. The median incubation period was 6.5 hours (range, 1.5-15 hours). Ill persons were almost five times more likely to have consumed minestrone soup than were those who were not ill (relative risk = 4.92, 95% confidence interval 1.23-infinity). Bacteriologic analysis identified C. perfringens in the soup and in 11 of 12 stool specimens from ill persons. The soup was cooked 2 days prior to serving and was slowly cooled before refrigeration; it was briefly reheated on the day served. Failure to monitor time and temperature controls during the cooling and reheating of the soup probably allowed for C. perfringens proliferation in the minestrone soup. This investigation demonstrated that nonanimal protein sources, such as legumes, can support substantial C. perfringens growth and should be regarded as potential vehicles in C. perfringens outbreaks.


Estrogen replacement therapy in women with breast cancer: a survey of patient attitudes.

Estrogen replacement therapy (ERT) is suggested for women with symptomatic estrogen deficiency, but patients with breast cancer are advised against ERT because of concerns that ERT may precipitate cancer recurrence. The attitudes of women with breast cancer regarding ERT is critical in the design of appropriate strategies for the management of their menopause. A randomly selected group of 224 women with breast cancer responded to an anonymous survey that addressed the presence of menopause, antecedent therapies, symptoms related to estrogen deficiency, concerns about osteoporosis or heart disease, attitude about ERT, and perception about ERT-related cancer risk. Among women who completed the survey, 77% were postmenopausal and 81% had had multimodality therapy. Of menopausal women, 27% believed they needed some treatment for menopause and 8% had taken ERT since cancer diagnosis. Most women were afraid that ERT may precipitate cancer recurrence (78%) but they also were concerned about the menopause-related risk of osteoporosis (70%) and heart disease (72%). Overall, 44% of menopausal women were willing to consider ERT under medical supervision. Those treated with surgery alone were distinct in that 71% would consider ERT (p < 0.04). Premenopausal women were more concerned about osteoporosis (82% vs. 66% for postmenopausal), heart disease (92% vs. 73%), and the possibility that ERT may precipitate cancer recurrence (98% vs. 73%). Yet, at the same time, they were more willing to consider ERT under medical supervision (59% vs. 40% for menopausal). The present study underscores that women with breast cancer are very aware and concerned about the adverse health consequences of estrogen deficiency and would consider ERT under medical supervision.(ABSTRACT TRUNCATED AT 250 WORDS)


Potassium and catecholamine concentrations in the immediate post exercise period.

The minutes immediately after cessation of strenuous exercise have been termed the "vulnerable period" regarding the occurrence of lethal cardiac arrhythmias. In the present study, we analyzed the rates of change with a high degree of temporal resolution of factors known to be associated with induction of arrhythmic activity. Thirteen subjects walked and ran on a treadmill to the point of exhaustion after a modified Bruce protocol. Samples were drawn from the antecubital vein immediately before exercise, at the moment exercise stopped, and at 1, 2, 3, 5, and 10 minutes of recovery. Plasma potassium concentration rose during exercise from 3.98 +/- .05 to 5.09 +/- .09 mEq/L. After the exercise period, plasma potassium fell rapidly. The mean maximum rate of change was -0.54 +/- .04 mEq/L/min, and -0.88 +/- .08 mEq/L/2 min. Plasma epinephrine concentration increased from 63 +/- 14 to 497 +/- 41 pg/ml and norepinephrine increased from 503 +/- 57 to 2800 +/- 519 pg/ml during exercise. During the first minute after cessation of exercise, the concentrations of both catecholamines increased still further. We propose that the rapid decline of potassium concentration while catecholamine levels are elevated to near maximal levels may contribute to the vulnerability of some individuals to post exercise arrhythmias.


Case report: a glucose responsive insulinoma--implication for the diagnosis of insulin secreting tumors.

Normal insulin secretagogues, including glucose, usually have little influence on insulin secretion from insulinomas. Therefore, insulinomas typically cause fasting hypoglycemia with relative hyperinsulinemia. This report describes a patient with hyperinsulinemia due to an islet cell adenoma with microadenomatosis, which, upon provocative in vivo testing, was found to be profoundly responsive to hypoglycemic and hyperglycemic stimuli. A 72 hr fast followed by brisk exercise resulted in a gradual reduction of serum glucose and insulin concentrations, but did not provoke symptomatic hypoglycemia. Oral glucose tolerance testing resulted in a prompt 10-fold increase in serum insulin accompanied by a mildly symptomatic and gradual fall in serum glucose to 30 mg/dl 90 minutes after glucose ingestion. An intravenous glucose challenge caused an acute increase in serum insulin to more than 1200 microU/ml with a resulting serum glucose of 11 mg/dl 25 minutes later, associated with loss of consciousness. Although a prolonged fast has proven to be the best diagnostic test for insulin secreting tumors, many other provocative tests that use normal insulin secretagogues have been somewhat useful in this regard. The patient in this report supports the concept that insulinomas vary widely in their response to a number of normal physiologic regulators of insulin secretion, including the serum glucose concentration. A variety of provocative tests may be needed to fully evaluate the rare patient in whom there is a strong clinical suspicion of insulinoma but who has a nondiagnostic prolonged fast.


Failure of therapy for tuberculosis in human immunodeficiency virus infection.

Optimum treatment of tuberculosis in persons with human immunodeficiency virus (HIV) infection is still being defined. Tuberculosis treatment failure in an HIV-infected patient is described and 10 similar cases from the medical literature are reviewed to search for common patterns associated with an adverse outcome of therapy in this setting. Six patients were poorly compliant. In nine patients, the subsequent episode of tuberculosis was disseminated or extrapulmonary; in four the central nervous system was involved. In five patients, a problem with rifampin usage was encountered: Three had rifampin-resistant Mycobacterium tuberculosis, one experienced an adverse reaction to rifampin, leading to withdrawal from the regimen after 1 week, and one was receiving a drug that may interfere with rifampin's antimycobacterial effect. This case report and literature review suggest that particular attention should be directed toward ensuring that patients with HIV infection comply with treatment of tuberculosis. For the majority of patients, the already stretched resources available for the treatment of tuberculosis and HIV infection should be devoted to compliance enhancement rather than to more prolonged or intensive drug regimens. However, it should be emphasized that patients with disseminated tuberculosis or central nervous system disease and those who are not able to receive rifampin because of drug resistance or an adverse reaction should be managed individually.


HIV and skin disease: the molecular biology of the human immunodeficiency virus.

The human immunodeficiency virus (HIV) is a member of a family of retroviruses that cause chronic persistent infections in animals and in humans. The structure of this virus resembles that of other retroviruses but also contains important and complex regulatory elements. The expression of HIV can be influenced by the action of exogenous agents and cytokines. HIV has been isolated from a number of cell types, including cells in the skin, using sensitive detection methods such as the polymerase chain reaction and in situ hybridization. This article is a basic overview of the molecular biology of HIV and its presence in skin.


AIDS in Romania.

Of the 1446 AIDS cases reported in Romania, 79% were in the pediatric age group. Of these children, 28% lived with their families, 30% were orphans, and 42% were abandoned. Among the AIDS-affected children, 32% were less than 1 year old and 67% were 1-4 years old. The natural history of AIDS in Romania was characterized by a high death rate from opportunistic infections. Chronic undernutrition imposed by the communist program of "rational feeding of the population," immunodepression induced by the radiation generated by the accident at Chernobyl, hard physical work in an environment intensely polluted by industrial waste, excessive use of injectable therapies and transfusions of HIV-untested blood, lack of education of the medical staff and the population, and tourism have contributed to the AIDS epidemic in Romania. Kaposi's sarcoma was infrequent (7.7%) in AIDS patients. However, a significant number of European-type Kaposi's sarcoma cases with negative tests for the HIV infection were reported.


Mechanism and role of insulin receptor endocytosis.

Like many other cell surface receptors for nutrients and polypeptide hormones, the insulin receptor undergoes a complex endocytotic itinerary. Upon insulin binding, the receptor is activated as a tyrosine-specific protein kinase and autophosphorylates. This autophosphorylation is necessary for the receptor to internalize. After endocytosis, the ligand (insulin) and its receptor are dissociated. Most of the insulin is degraded, whereas the receptors are largely recycled to the cell surface. The signals in the receptor that control and specify its endocytotic pathway are beginning to be understood. Through the techniques of in vitro mutagenesis, noninternalizing receptors have been engineered and their structural and functional properties have been analyzed. For example, the immediate submembranous domain of the insulin receptor has been found to contain sequences (Gly-Pro-Leu-Tyr and, to a lesser extent, Asn-Pro-Gln-Tyr) that are necessary for normal endocytosis. Receptors deleted or mutated in these sequences retain tyrosine kinase activity but fail to undergo endocytosis. Unlike the better understood low density lipoprotein and transferrin receptors, however, these sequences are not sufficient for endocytosis. An insulin receptor with only these sequences exposed in the cytoplasm does not internalize. Tyrosine kinase activity is thought to be needed to lead to autophosphorylation and a conformational change that exposes the otherwise buried endocytosis sequences in the normally dimerized insulin receptor. Non-internalizing mutants of the insulin receptor have been used to examine the role of endocytosis in insulin action. It was found that an endocytosis-defective receptor could induce a short-term metabolic action of insulin (glycogen synthetase stimulation) as well as longer-term mitogenic effects of insulin. Furthermore, insulin action deactivated after the hormone was removed from the noninternalizing receptors. Apparently, endocytosis is not necessary for insulin action, but probably is important for removing the insulin from the cell so the target cell for insulin responds in a time-limited fashion to the hormone.


Advances in monoclonal antibody therapy of cancer.

Tumor-associated antigens can be seen as unique targets for the delivery of anti-cancer therapy. Monoclonal antibodies directed at such antigens are increasingly being seen as important biologic reagents that will complement the group of existing cytotoxic drugs. This report briefly overviews recent advances in the field of monoclonal antibody therapy of cancer and provides insight regarding the promises and limitations of this novel therapeutic approach.


Characterization of cultured chemoreceptor cells dissociated from adult rabbit carotid body.

Short-term cell cultures were obtained from enzymatically dissociated carotid bodies from adult rabbits, and morphological and functional characterization of the cultured chemoreceptor cells were carried out. Under phase contrast, freshly isolated type I cells are round, bright, and 10-14 microns in diameter and exhibit strong fluorescence when stained with the glyoxylic acid technique. The content of endogenous dopamine in the cultures increased from 80 pmol/10(5) cells 2 h after plating the cells to 200 pmol/10(5) cells on the 3rd day, and the rate of synthesis and storage of [3H]dopamine from the precursor [3H]tyrosine increased from 1.7 pmol.10(5) cells-1.h-1 in 1-day cultures to 4 pmol.10(5) cells-1.h-1 on the 3rd day; the later values represent 80-85% of the expected values for the intact carotid body. After labeling with [3H]tyrosine, cultured chemoreceptor cells release [3H]dopamine when challenged by hypoxia, high external K+, or the protonophore dinitrophenol, the pattern of response being similar to that of the intact carotid body. When studied by whole cell clamp recording, individual chemoreceptor cells exhibit a marked variability in the properties of some ionic currents; the data, however, do not support the existence of distinct subpopulations of type I cells.


Negative-feedback regulation of excitation-contraction coupling in gastric smooth muscle.

The role of phosphatidylinositol (PI) turnover in excitation-contraction coupling was investigated in canine antral smooth muscle. Acetylcholine (ACh; 0.1-1 microM) transiently increased tissue levels of inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] and increased the amplitudes of the plateau phase of slow waves and associated Ca2+ transients and phasic contractions. ACh also increased basal concentrations of cytosolic Ca2+ ([Ca2+]c), but these changes were not associated with an increase in resting tension. ATP (0.3 mM) had similar effects on Ins(1,4,5)P3 levels, basal [Ca2+]c, and resting tension. However, in contrast to the effects of ACh, ATP transiently reduced the amplitude of the plateau phase of slow waves and reduced the amplitudes of associated Ca2+ transients and phasic contractions. We investigated the possibility that two products of PI turnover, diacylglycerol (DAG) and Ins(1,4,5)P3, might provide negative feedback to regulate Ca2+ entry during slow waves. 1) DAG is known to activate protein kinase C (PKC). Activation of PKC by phorbol 12,13-dibutyrate (PDBu, 0.5 microM) reduced the amplitude of the plateau phase of slow waves and corresponding Ca2+ transients and phasic contractions. Assay of PKC showed that ACh, ATP, and PDBu stimulated enzyme activity. 2) Ins(1,4,5)P3 is known to increase [Ca2+]c by release of Ca2+ from internal stores. Basal [Ca2+]c was also increased by elevated external K+, ionomycin, thapsigargin, or caffeine. Each of these compounds reduced the amplitude and duration of slow waves. Results suggest that products of PI turnover may provide negative-feedback control of Ca2+ influx during slow waves, tending to reduce the amplitude of phasic contractile activity in gastric muscles. Differences in responses to ACh and ATP can be explained by a G protein-dependent mechanism in which ACh suppresses the voltage dependence of Ca(2+)-activated K+ channels.


Loss of suppression of GSH synthesis at low cell density in primary cultures of rat hepatocytes.

Primary cultures of adult rat hepatocytes shift into the growth phase when plated at low density (LD). We used this model to examine changes in glutathione (GSH) metabolism, since cells undergoing active growth may be more susceptible to environmental toxins. When primary cultures of adult rat hepatocytes were plated on collagen or Matrigel-precoated dishes, cell number and GSH varied inversely. This density effect on cell GSH occurred as early as 2 h after plating, when the media contained 1 mM methionine, but was delayed until 20 h if the media contained only 0.5 mM cystine. The density effect on GSH synthesis occurred in the absence of serum, hormones, changes in cell volume, GSH efflux, ATP levels, and uptake of methionine or cystine and was blocked by cycloheximide or actinomycin D. When methionine was available, the cellular cysteine level was 65% higher at LD than at high density (HD). gamma-Glutamylcysteine synthetase (GCS) activity was 64% higher at LD than at HD. GSH synthetase activity was unaffected by density. Both the increase in cellular cysteine levels and GCS activity were blocked by cycloheximide and actinomycin D. When cells were cocultured using cluster plates and Transwell inserts for 4 h, cell GSH of HD cells was unaffected by the density of cocultured cells; however, LD cells exhibited significantly lower GSH and GCS activity when cocultured with HD cells than when cocultured with LD cells. Cysteine levels were elevated in the LD cells regardless of the density of cocultured cells.(ABSTRACT TRUNCATED AT 250 WORDS)


Calcium-activated phosphatidylcholine-specific phospholipase C and D in MDCK epithelial cells.

Calcium ionophore exposure generates diglycerides (DAG) from phosphatidylcholine (PC) hydrolysis in Madin-Darby canine kidney (MDCK) epithelial cells. This study compares calcium ionophore-activated PC hydrolysis with the previously described phorbol ester-stimulated PC hydrolysis pathway using MDCK cells labeled with [14C]-linoleic acid. Lipid species were measured using thin-layer chromatography. DAG resulted in part from PC hydrolysis because DAG increased in cells labeled with [palmitoyl-2-14C]phosphatidylcholine. Neither protein kinase C (PKC) inhibitors nor PKC depletion affected the ionomycin (IONO)-induced increase in DAG. Ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid prevented the increased DAG after IONO but not after phorbol 12,13-dibutyrate (PDBu) exposure. The EGTA effect was reversed by adding excess calcium but was not reversed by adding excess Mg2+. IONO exposure also increased phosphatidic acid (PA) production. The PA was produced by phospholipase D (PLD) because phosphatidylethanol was produced when IONO was added to the cells in the presence of ethanol. Although increasing concentrations of ethanol resulted in progressively less PA, it had no effect on increased DAG after IONO exposure at any time point tested. These data are consistent with both increased phospholipase C (PLC) and increased PLD activity following ionomycin. In contrast to IONO exposure, ethanol completely prevented the increase in DAG after PDBu exposure, consistent with DAG produced by PLD activation. These results demonstrate that calcium activates both PC-specific PLC and PLD in MDCK cells and that the calcium-activated pathway is independent of the previously described PKC activation pathways.


Expression of the Na-Ca exchanger in diverse tissues: a study using the cloned human cardiac Na-Ca exchanger.

In many cells including cardiac myocytes, cytoplasmic Ca is importantly controlled by the plasmalemmal Na-Ca exchanger (3, 8). The tissue diversity and differences in cellular environment raise the question whether the same exchanger is found in all tissues. Recent experiments using rod cells have demonstrated that at least two forms of Na-dependent Ca transport exist. We have examined this issue in various rat and human tissues using the cloned human cardiac Na-Ca exchanger cDNA. Northern blot analysis in these two species show that the major transcript of the Na-Ca exchanger is 7.2 kilobases in heart, brain, kidney, liver, pancreas, skeletal muscle, placenta, and lung. Furthermore, ribonuclease protection analysis in rats shows conservation of the 348-base pair segment tested in heart, brain, kidney, skeletal muscle, and liver. Additionally, Southern blot analysis suggests that a single gene encodes this Na-Ca exchanger. Finally, we show that the clone used to generate our probes encodes a completely functional Na-Ca exchanger. With the use of COS cells and 293 cells transfected with the cloned human cardiac Na-Ca exchanger, we tested the Ca transport properties of the Na-Ca exchanger, the voltage dependence of the Na-Ca exchanger, as well as the Na dependence of the transport function of the Na-Ca exchanger. We conclude that the cardiac form of the Na-Ca exchanger is completely functional when the cDNA is expressed in mammalian cell lines, and, furthermore, this "cardiac" form of the Na-Ca exchanger is naturally expressed in all human and rat tissues tested (but at varying levels).


Transport of choline by plasma membrane vesicles from lung-derived epithelial cells.

A549 cells, a lung epithelium-derived cell line, were used as a model system to study choline transport by granular pneumocytes. Intact cells accumulated free choline against a concentration gradient by a low-affinity transport system with kinetic characteristics similar to that previously described for granular pneumocytes (Am. J. Respir. Cell Mol. Biol. 1: 455, 1989). Membrane vesicles prepared from these cells showed a 10-fold enrichment in plasma membrane marker enzymes with a vesicular H2O space of 5.7 +/- 0.05 (SE) microliters/mg protein. Vesicles showed a time- and concentration-dependent uptake of free [3H]choline in Na(+)-free medium. With 5 microM choline, choline uptake reached an apparent steady-state concentration gradient (inside/outside) of 50. 3H that was membrane associated ("bound" choline) represented approximately 5% of total uptake. In the presence of an initial gradient of NaCl, choline uptake showed an overshoot with a plateau value similar to Na(+)-free conditions; a similar effect was observed for plasma membrane vesicles from rat lung type 2 epithelial cells. The steady-state uptake of choline was inhibited at low pH (6.5) and by the presence of valinomycin or carbonyl cyanide p-tri-fluoromethoxyphenylhydrazone and was abolished when both were present. These results show that plasma membrane vesicles from A549 cells accumulate choline by binding to the membranes and by Na(+)-dependent and -independent transport mechanisms, the latter apparently reflecting a transmembrane proton gradient.


Regulation of pHi in Saos-2 cells by thrombin: roles of proteolytic activity and cytosolic calcium transients.

Some, if not all, of the cellular actions of alpha-thrombin are now believed to be mediated by proteolytic cleavage of the cell surface thrombin receptor to yield a tethered ligand that initiates signal transduction via the receptor. We have investigated the actions of alpha-thrombin on the regulation of cytosolic free Ca2+ concentration ([Ca2+]i) and intracellular pH (pHi) in human osteoblast-like Saos-2 cells. After acidification with nigericin, thrombin induced an acute increase of [Ca2+]i and a rise in pHi. The action of thrombin on pHi was dependent on activation of the Na(+)-H+ antiporter. Thrombin elicited parallel concentration-dependent increases in both [Ca2+]i and pHi, and the rise in [Ca2+]i was a prerequisite for the increase in pHi. Preincubation of thrombin with the active site proteolytic inhibitor, BOC-D-Phe-L-Pro-D,L-Lys-CF3, prevented the alkalinization response to thrombin but had little or no effect on the thrombin-induced rise in [Ca2+]i. Hirudin, a natural inhibitor of thrombin, acts by tight binding to several discrete regions on the thrombin molecule. Preincubation of thrombin with hirudin completely blocked the rise in both [Ca2+]i and pHi. These results demonstrate that the thrombin-induced rise in [Ca2+]i alone is not sufficient to cause alkalinization in Saos-2 cells. More importantly, our findings reveal that not all of the cellular actions of thrombin can be explained by proteolytic cleavage of the thrombin receptor and suggest that different domains on the thrombin molecule may be required for eliciting signals that raise [Ca2+]i and pHi in Saos-2 cells.


Role for diacylglycerol in mediating the actions of ACh on M-current in gastric smooth muscle cells.

The role of the second messenger diacylglycerol (DAG) in mediating muscarinic suppression of M-current, a type of a voltage-gated K+ current that is suppressed by acetylcholine (ACh), was examined in freshly isolated smooth muscle cells from toad stomach. Currents were recorded using a single electrode voltage clamp employing conventional microelectrodes. Extracellular application of 1,2-dioctanoyl-sn-glycerol (DiC8), a synthetic DAG that is a potent activator of protein kinase C (PKC), reversibly suppressed M-current. Current relaxations, representing the voltage-dependent closure of K+ channels underlying M-current, were also decreased by DiC8, although suppression was not always as complete as it was with ACh. In contrast, another DAG analogue, 1,2-dioctanoyl-3-thioglycerol, which has a structure closely related to DiC8 but does not activate PKC, failed to inhibit M-current. Furthermore, M-current induced by the beta-agonist isoproterenol, by a mechanism apparently mediated by adenosine 3',5'-cyclic monophosphate (S. M. Sims, L. H. Clapp, J. V. Walsh, Jr., and J. J. Singer. Pflugers Arch. 417: 291, 1990), was also suppressed by DiC8. Both ACh and DiC8 were found to suppress endogenous and isoproterenol-induced M-current without altering the time course of M-current deactivation, suggesting that these agents act by decreasing the number of channels available to be opened. These results provide evidence that muscarinic regulation of M-current is mediated by DAG.


Osmoregulation of Na(+)-inositol cotransporter activity and mRNA levels in brain glial cells.

During plasma hypertonicity brain volume is regulated acutely by electrolyte uptake and chronically by accumulation of organic solutes such as inositol. Cultured rat C6 glioma cells, an astrocyte-like cell line, show a similar pattern of volume control. Volume regulatory accumulation of inositol requires external inositol, indicating that membrane transport plays a central role in this process. The inositol uptake pathway is Na+ dependent and exhibits Michaelis-Menten kinetics. Chronic hypertonic acclimation results in a twofold increase in the maximum velocity of the transporter without changing the Km. Hypertonic stress also results in a 17-fold increase in transporter mRNA. Elevation of mRNA levels precedes activation of the transporter by 4-6 h, suggesting that increased inositol uptake is mediated by synthesis and membrane insertion of new transport proteins. Reacclimation of hypertonic cells to isotonicity causes a rapid reduction of transporter mRNA levels to control levels within 4 h. In contrast, downregulation of transport activity does not begin until between 10 and 24 h after reexposure to isotonicity.


Endothelin-1 stimulates DNA synthesis and proliferation of pulmonary artery smooth muscle cells.

Endothelin-1 (ET-1), a 21-amino acid peptide released from the endothelium, elicits a variety of biological effects that include vascular smooth muscle cell (VSMC) contraction, release of secondary mediators, and cell proliferation. The present study was undertaken to examine the proliferative potential of ET-1 toward pulmonary artery VSMC in culture. In the presence of low serum and epidermal growth factor (EGF), ET-1 stimulated marked DNA synthesis and proliferation of VSMC. The contributing factor from serum appeared to be platelet-derived growth factor (PDGF) because the antibody to PDGF eliminated the stimulatory activity. The antibody to EGF also prevented the stimulation, suggesting that both PDGF and EGF are required for the full expression of the VSMC growth-promoting activity of ET-1. A paradoxical aspect of ET-1 effect on VSMC was the ability of ET-1 to inhibit the EGF-stimulated DNA synthesis when the two factors were added together to a high baseline DNA synthetic activity. The inhibition was prevented if ET-1 was added 12-18 h after the addition of EGF or if ET-1 and EGF were added to a protein kinase C-depleted VSMC. The inhibition by ET-1 may be mediated by protein kinase C activation followed by inhibition of EGF binding to its receptor. The results indicate that ET-1 under appropriate conditions can modulate the growth of pulmonary artery VSMC in both positive and negative directions.


Simultaneous fluorescence measurement of calcium and membrane potential responses to endothelin.

Vasopressin stimulates calcium signaling and chloride-dependent depolarization in glomerular mesangial cells. We describe a technique whereby both calcium and membrane potential changes can be simultaneously monitored with fluorescent probes. This technique was validated by comparison with single parameter measurements in basal and vasopressin-stimulated mesangial cells. It was shown that the calibration for calcium is unaffected by that for membrane potential, whereas the calibration for membrane potential is affected by prior calcium calibration. Accordingly, it was necessary to calibrate for the former first. The technique was then applied to investigate the effects of endothelin, which was found to elicit a concentration-dependent calcium release response and a chloride-dependent depolarization of mesangial cells. The interaction between the calcium signaling response to vasopressin and endothelin was also investigated. When vasopressin stimulation occurred subsequent to endothelin stimulation, and vice versa, a calcium response was still evident. However, these agonists displayed partial heterologous desensitization in that prior stimulation with vasopressin attenuated the subsequent response to endothelin, and vice versa. This suggests the presence of functionally distinct hormone-responsive calcium pools. The technique of double-parameter fluorescent measurement outlined could potentially be applied to other cellular signaling parameters by the use of the appropriate probes.


Fish antifreeze proteins block Ca entry into rabbit parietal cells.

Many fish and insects have adapted to life at subfreezing temperatures by evolving so-called antifreeze proteins (AFP) that noncolligatively depress the freezing temperatures of aqueous solutions without affecting the melting temperature. AFP have been thought to function solely as antifreezes. Recently, however, we discovered that AFP also protect mammalian cells and organs from damage caused by exposure to hypothermic (above freezing) temperatures. It has been proposed that hypothermic damage is caused by changes in intracellular ionic content due to a reduction of active transport that is required to balance passive ion transport across cell membranes. Given this possibility, we tested whether AFP isolated from the Newfoundland ocean pout might reduce the Ca ion permeability of a mammalian cell, the rabbit gastric parietal cell, which has been particularly well studied in terms of Ca transport and signaling. Digital image processing of the Ca-sensitive fluorescent indicator fura-2 was used to measure intracellular free Ca in these cells. During stimulation with the cholinergic agonist carbachol, AFP inhibited passive Ca entry across the cell membrane without interfering with either the release of Ca from internal stores (indicating that the carbachol receptor and other signaling events were operational) or the normal active rates of Ca efflux from the cell (indicating that Ca pumping was also still intact). These results suggest that, in addition to their actual antifreeze properties, AFP may also help to confer cold tolerance in animals by preventing passive Ca entry into epithelial cells.


Disuse osteopenia is accompanied by downregulation of gene expression for bone proteins in growing rats.

Unilateral sciatic neurectomy (USN) resulted in cortical osteopenia in tibiae from the sciatic nerve-sectioned limb of growing rats. The bone deficit resulted from decreased periosteal addition; there were no changes in the indexes of bone resorption. The periosteal bone formation rate was reduced in the nerve-sectioned limb within 7 days of sciatic neurectomy, and this decrease persisted for at least 56 days. Steady-state mRNA levels for bone proteins were determined in periosteum isolated from tibiae and femurs 7 and 14 days after sciatic nerve section. Nerve section resulted in decreased levels of mRNA for osteocalcin, alkaline phosphatase, and possibly the prepro-alpha (I)-subunit of type I collagen (collagen). The effects were more pronounced in tibiae than femurs, corresponding to the greater degree of immobility induced by USN in the former bone. The results demonstrate that decreased bone formation precedes establishment of disuse cortical osteopenia in growing rats with no evidence for a change in bone resorption. Furthermore, the decreased bone formation is associated with, and may be due to, reduced mRNA levels for matrix proteins and other important bone proteins.


Lactate in rat skeletal muscle after hemorrhage measured by microdialysis probe calibrated in situ.

The interstitial lactate concentration in rat skeletal muscle was measured in the normal state and after hemorrhage using a microdialysis probe, and the values calculated by in vitro and in vivo calibration were compared. After withdrawal of 30% of the estimated total blood volume, the lactate concentration in the dialysate gradually increased and then maintained an almost constant level. It was found that interstitial lactate levels of skeletal muscle calculated by the in vitro calibration method were not significantly different from those calculated by in vivo calibration in both the normal state and after hemorrhage. These data indicate that the absolute lactate concentration in the muscle interstitium in the normal state and after acute hemorrhage can be practically measured by a microdialysis probe calibrated in vitro. From the comparison of lactate concentrations in blood and in the muscle interstitium, it was suggested that rat skeletal muscle functions as a lactate consumer, rather than as a lactate producer, after acute hemorrhage.


Effect of moderate cold exposure on 24-h energy expenditure: similar response in postobese and nonobese women.

Twenty-four-hour energy expenditure (EE) and substrate oxidation rates were measured two times in eight postobese women and eight matched controls. On one occasion the subjects were exposed to a room temperature of 16 degrees C, on the other to 24 degrees C. Cold exposure elicited a 2% increment in 24-h EE (P < 0.05), with similar response in the two groups. The slight increase in EE was entirely covered by an enhanced carbohydrate oxidation rate. Fasting plasma norepinephrine (NE) increased from 0.74 +/- 0.08 to 1.29 +/- 0.21 nmol/l under cold exposure (P < 0.05), with no group difference. The cold-induced increase in 24-h EE was positively correlated to the increase in NE concentration (r2 = 0.41, P = 0.01). Sleeping EE was found to be 5% lower in the postobese women than in the controls (P = 0.04). The postobese group also had higher 24-h nonprotein respiratory quotient than the control group (P = 0.04), which was due to a 26% lower lipid-to-carbohydrate oxidation ratio. The study demonstrates that the thermogenic response to cold is normal in women susceptible to obesity, but it supports previous reports of a slightly lower basal EE and lower lipid-to-carbohydrate oxidation ratio in postobese subjects.


Effects of high levels of fatty acids on functional recovery of ischemic hearts from diabetic rats.

In this study we determined the effects of high levels of fatty acids on recovery of heart function when present either during or after ischemia. Isolated working hearts from 6-wk streptozotocin diabetic and control rats perfused with 11 mM glucose were subjected to 25 min of global ischemia followed by 30 min of aerobic reperfusion. Four groups were studied: 1) 1.2 mM palmitate present before, during, and after ischemia; 2) 1.2 mM palmitate present before and during ischemia, followed by reperfusion in the absence of palmitate; 3) no palmitate before and during ischemia, followed by 1.2 mM palmitate during reperfusion; and 4) no palmitate before and during ischemia or during reperfusion. In control hearts, palmitate during reperfusion depressed recovery of function regardless of whether palmitate was present or absent during ischemia. In contrast, palmitate present during reperfusion did not depress recovery of mechanical function in the diabetic rat hearts. However, the presence of palmitate during ischemia itself in diabetic rat hearts was detrimental to recovery of mechanical function. The presence of palmitate during ischemia resulted in an accelerated rate of ATP loss and a decreased rate of lactate accumulation during ischemia, although this effect was similar in control and diabetic rat hearts. Our results demonstrate that high concentrations of fatty acids depress functional recovery of control rat hearts during the reperfusion period but depress recovery of function in diabetic rat hearts when present during ischemia itself.


Upregulation of V1a vasopressin receptors by glucocorticoids.

WRK1 cells (a rat mammary tumor cell line) exhibit a vasopressinergic receptor of V1a subtype tightly coupled to phospholipase C. Addition of dexamethasone to the culture medium principally potentiated the vasopressin-sensitive accumulation of inositol phosphates and to a lesser extent the NaF-sensitive phospholipase C activity. On the opposite, such treatment was without effect on the basal level of intracellular inositol phosphates or on bradykinin- or serotonin-sensitive phosphoinositide metabolisms. Glucocorticoid receptors were probably involved in these actions since dexamethasone was found to be more potent than aldosterone or corticosterone. Dexamethasone treatment also increased the number of vasopressin binding sites without affecting its affinity for vasopressin or other specific vasopressin analogues. These results strongly suggest that dexamethasone principally acts at the vasopressin receptor level by affecting its synthesis and/or the translation of its mRNA and also affects the G protein that couples the V1a receptor to the phospholipase C. These results explain how glucocorticoids may regulate the transduction mechanisms involved in vasopressin actions on WRK1 cells. They provide explanations for understanding the cross talk between adrenal steroids and hormones, which mobilize intracellular calcium.


Regulation of free fatty acid metabolism by insulin in humans: role of lipolysis and reesterification.

The regulation of lipolysis, free fatty acid appearance into plasma (FFA R(a)), an FFA reesterification and oxidation were examined in seven healthy humans infused intravenously with insulin at rates of 4, 8, 25, and 400 mU.m-2.min-1. Glycerol and FFA R(a) were determined by isotope dilution methods, and FFA oxidation was calculated by indirect calorimetry or by measurement of expired 14CO2 from infused [1-14C]palmitate. These measurements were used to calculate total FFA reesterification, primary FFA reesterification occurring within the adipocyte, and secondary reesterification of circulating FFA molecules. Lipolysis, FFA R(a), and secondary FFA reesterification were exquisitely insulin sensitive [the insulin concentrations that produced half-maximal suppression (EC50), 106 +/- 26, 91 +/- 20 vs. 80 +/- 16 pM, P = not significant] in contrast to insulin suppression of FFA oxidation (EC50, 324 +/- 60, all P < 0.01). The absolute rate of primary FFA reesterification was not affected by the increase in insulin concentration, but the proportion of FFA molecules undergoing primary reesterification doubled over the physiological portion of the insulin dose-response curve (from 0.23 +/- 0.06 to 0.44 +/- 0.07, P < 0.05). This served to magnify insulin suppression of FFA R(a) twofold. In conclusion, insulin regulates FFA R(a) by inhibition of lipolysis while maintaining a constant rate of primary FFA reesterification.


1,25(OH)2D3 blunts hormone-elevated cytosolic Ca2+ in osteoblast-like cells.

Cytosolic free calcium ([Ca2+]i) is an important regulator of bone cell physiology. We studied the interaction of vitamin D metabolites on the hormonal-activated Ca message system in the osteoblastic cell line UMR-106. The acute rise in [Ca2+]i induced by different calciotropic hormones [parathyroid hormone, prostaglandin E2 (PGE2)] was dose dependently blunted by 1,25-dihydroxyvitamin D [1,25(OH)2D3; half-maximal inhibitory concn approximately 5 x 10(-11) M] and was initially observed after 8 h of preincubation. The 1,25(OH)2D3 metabolite of vitamin D was two orders of magnitude more potent than 24,25(OH)2D3 and 25(OH)D3. To discern between an effect of 1,25(OH)2D3 on hormonal-induced Ca2+ entry through the plasma membrane channel vs. release of Ca2+ from internal stores, we suspended fura-2-loaded cells in Mn2+ rather than Ca2+ buffers. In cells preincubated with 1,25(OH)2D3, [Ca2+]i release (indicated by [Ca2+]i transient) was significantly blunted, whereas Mn2+ influx (indicating Ca2+ flux across the plasma membrane) was unaltered, suggesting a selective effect of 1,25(OH)2D3 on hormonal-activated release of Ca2+ from intracellular stores. 1,25(OH)2D3 also inhibited the PGE2-induced production of inositol 1,4,5-trisphosphate. We conclude that, in osteoblasts, chronic (hours) incubation with 1,25(OH)2D3 leads to attenuated stimulation of the [Ca2+]i transduction pathway by calciotropic hormones. This effect of 1,25(OH)2D3 may provide a cellular basis for the synergism between the effects of vitamin D and calciotropic hormones at the bone level.


Production of parathyroid hormone-related protein by the rat mammary gland in pregnancy and lactation. Am. J. Physiol. 263 (Endocrinol. Metab. 26): E1077-E1085, 1992.--Production of parathyroid hormone-related protein (PTHrP) by the mammary gland of Sprague-Dawley rats has been examined using immunohistochemistry and in situ hybridization to detect PTHrP and PTHrP mRNA, respectively. PTHrP and PTHrP mRNA could be demonstrated in nests of epithelial cells of the developing mammary gland at day 14 of pregnancy and in the epithelial secretory cells lining the alveoli during the latter stages of pregnancy and during lactation. A specific radioimmunoassay was also used to measure the concentration of PTHrP secreted in the milk throughout lactation. The concentration of PTHrP in milk was relatively low initially but increased during the latter stages of lactation, whereas calcium concentrations remained virtually constant throughout lactation. No correlation was found between the concentrations of calcium and PTHrP in rat milk. These results show that PTHrP is present in rat milk and also in mammary tissue before parturition, and therefore it may assist in the development of the mammary gland during pregnancy.


Hypoxia causes glycogenolysis without an increase in percent phosphorylase a in rat skeletal muscle.

Stimulation of skeletal muscle to contract activates phosphorylase b-to-a conversion and glycogenolysis. Despite reversal of the increase in percentage of phosphorylase a after a few minutes, continued glycogen breakdown can occur during strenuous exercise. Hypoxia causes sustained glycogenolysis in skeletal muscle without an increase in percentage of phosphorylase a. We used this model to obtain insights regarding how glycogenolysis is mediated in the absence of an increase in percentage of phosphorylase a. Hypoxia caused a 70% decrease in glycogen in epitrochlearis muscles during an 80-min incubation despite no increase in percentage of phosphorylase a above the basal level of approximately 10%. Muscle Pi concentration increased from 3.8 to 8.6 mumol/g muscle after 5 min and 15.7 mumol/g after 20 min. AMP concentration doubled, attaining a steady state of 0.23 mumol/g in 5 min. Incubation of oxygenated muscles with 0.1 microM epinephrine induced an approximately sixfold increase in percentage of phosphorylase a but resulted in minimal glycogenolysis. Muscle Pi concentration was not altered by epinephrine. Despite no increase in percentage of phosphorylase a, hypoxia resulted in a fivefold greater depletion of glycogen over 20 min than did epinephrine. To evaluate the role of phosphorylase b, muscles were loaded with 2-deoxyglucose 6-phosphate, which inhibits phosphorylase b. The rate of glycogenolysis during 60 min of hypoxia was reduced by only approximately 14% in 2-deoxyglucose 6-phosphate-loaded muscles.(ABSTRACT TRUNCATED AT 250 WORDS)


Development and application of a radioimmunoassay to detect interleukin-1 in rat peripheral circulation.

We describe the development and application of a radioimmunoassay to detect circulating interleukin (IL)-1 beta concentrations in the rat. No IL-1 immunoreactivity above the detection limit of the assay (100 pg/ml) could be detected in plasma of control rats. In contrast, immunoreactive IL-1 was detected after intravenous administration of rat recombinant IL-1 beta (rrIL-1 beta) or bacterial lipopolysaccharide (LPS) to rats. The effect of LPS on plasma immunoreactive IL-1 concentrations was time and dose dependent. The immunoreactive IL-1 response to LPS was prevented by in vivo macrophage depletion induced by liposome-directed macrophage suicide technique. Gel filtration of plasma from LPS-treated rats revealed the presence of a high and a smaller molecular form of immunoreactive IL-1. The small molecular immunoreactive IL-1 peak coeluted with rrIL-1 beta and probably represents the 17-kDa form of IL-1 beta. In conclusion, our data support the hypothesis that IL-1 secreted by macrophages can act as a humoral signal molecule to induce the immunological, metabolic, and neuroendocrine changes in response to bacterial LPS.


Chronic infusion of TNF-alpha reduces plasma T4 binding without affecting pituitary-thyroid activity in rats.

In the present study the effects of continuous administration of tumor necrosis factor-alpha (TNF-alpha), in a dose not affecting body temperature and food intake, on pituitary-thyroid function of rats were investigated. Male rats, bearing a venous catheter to allow repeated blood sampling, were intraperitoneally equipped with osmotic minipumps that continuously delivered recombinant human TNF-alpha (8.0 micrograms/day ip) or saline for 7 days. Infusion of TNF-alpha resulted in a significant decrease of plasma total thyroxine (T4) levels during days 2-5 of infusion as compared with the levels in saline-infused rats. This suppression of plasma T4 concentrations was caused by a decreased binding of T4 in plasma, as indicated by an increased percentage of free T4. TNF-alpha infusion did not significantly affect free T4 levels in plasma nor basal and thyrotropin-releasing hormone-stimulated TSH levels. The decreased binding of T4 was, at least partially, caused by a reduction of T4-binding prealbumin (TBPA) levels in plasma, which were significantly reduced during the first 3 days of TNF-alpha infusion. Plasma levels of free fatty acids were not affected by TNF-alpha. TNF-alpha treatment did not influence the plasma 3,5,3'-triiodothyronine (T3)-to-T4 ratio nor hepatic 5'-deiodinase activity. Plasma reverse T3 levels remained undetectable both in control and TNF-alpha-treated rats. Taken together, our findings indicate that chronic infusion of rats with TNF-alpha in a subpyrogenic and subanorectic dose induces a transient decrease of plasma T4 binding without affecting pituitary-thyroid activity and peripheral thyroid hormone metabolism.(ABSTRACT TRUNCATED AT 250 WORDS)