NMR determination of residual structure in a urea-denatured protein, the 434-repressor.

A nuclear magnetic resonance (NMR) structure determination is reported for the polypeptide chain of a globular protein in strongly denaturing solution. Nuclear Overhauser effect (NOE) measurements with a 7 molar urea solution of the amino-terminal 63-residue domain of the 434-repressor and distance geometry calculations showed that the polypeptide segment 54 to 59 forms a hydrophobic cluster containing the side chains of Val54, Val56, Trp58, and Leu59. This residual structure in the urea-unfolded protein is related to the corresponding region of the native, folded protein by simple rearrangements of the residues 58 to 60. Based on these observations a model for the early phase of refolding of the 434-repressor(1-63) is proposed.


Attention-based motion perception.

Two "attentive" tracking tasks reveal the existence of an attention-based motion process. In the first task, oppositely rotating luminance and color gratings were superimposed. Because of masking from the color grating, the bars of the luminance grating were not visible; nevertheless, their motion was visible and it determined the perceived direction of the stimulus rotation. On the other hand, the bars of the color grating were visible but they could only be seen to move (in the opposite direction to the overall stimulus rotation) when they were tracked with attention. In a second task, the perceived velocity of a color grating, typically slow at equiluminance, speeded up when individual bars were attentively tracked. These findings demonstrate two independent motion processes: one that is "low-level" or automatic in that it signals motion even in the absence of attention to the stimulus, and one that is mediated by attention to visible features and provides accurate velocity judgments independently of the features being tracked.


The origins of positron emission tomography.

The development of positron emission tomography (PET) took place through the combination of the following recognitions: (1) a handful of short-lived, positron-emitting radionuclides, carbon-11, nitrogen-13, and oxygen-15, exhibit chemical properties that render them particularly suitable for the tracing of important physiological pathways, and (2) the radiation emitted as a result of the annihilation of positrons in matter exhibited physical properties that made it well-suited for nuclear medicine imaging, particularly for tomographic reconstruction. The scientific building blocks that were necessary for the structure of PET were contributed over a period of several decades by many investigators in physics, mathematics, chemistry, and fundamental biology.


Cyclotrons and positron emission tomography radiopharmaceuticals for clinical imaging.

Positron emission tomography (PET) requires positron-emitting radionuclides that emit 511-keV photons detectable by PET imagers. Positron-emitting radionuclides are commonly produced in charged particle accelerators, eg, linear accelerators or cyclotrons. The most widely available radiopharmaceuticals for PET imaging are carbon-11-, nitrogen-13-, and oxygen-15-labeled compounds, many of which, either in their normal state or incorporated in other compounds, serve as physiological tracers. Other useful PET radiopharmaceuticals include fluorine-18-, bromine-75-, gallium-68 (68Ga)-, rubidium-82 (82Rb)-, and copper-62 (62Cu)-labeled compounds. Many positron emitters have short half-lives and thus require on-site cyclotrons for application, and others (68Ga, 82Rb, and 62Cu) are available from radionuclides generators using relatively long-lived parent radionuclides. This review is divided into two sections: cyclotrons and PET radiopharmaceuticals for clinical imaging. In the cyclotron section, the principle of operation of the cyclotron, types of cyclotrons, medical cyclotrons, and production of radionuclides are discussed. In the section on PET radiopharmaceuticals, the synthesis and clinical use of PET radiopharmaceuticals are described.


Instrumentation for positron emission tomography: tomographs and data processing and display systems.

The field of positron emission tomography (PET) has evolved over the past 10 to 15 years from a basic research endeavor to a field in which both research and clinical studies are performed at over 100 institutions and medical facilities throughout the world. Most centers now use tomographs supplied by commercial vendors and operate data analysis systems employing identical software packages. PET scanners have advanced from prototypes assembled more than 15 years ago that imaged a single slice with 32 detectors at a resolution of greater than 2.0 cm full-width-at-half-maximum (FWHM), to current state-of-the-art instruments that simultaneously image as many as 47 slices using nearly 10,000 detector crystals at resolutions of less than 5 mm FWHM. In addition, specialized research instruments have been developed that have in-plane image resolution of approximately 2.5 mm FWHM. Other PET instrumentation advances include the development of detector block designs with multiple crystals per photomultiplier tube, continuous large position-sensing detectors, and the use of new detector materials having properties particularly suited for PET imaging. Image display and analysis systems have also advanced considerably over this time period. Early scanners typically used analysis stations with dedicated displays of only approximately 256 x 256 pixels and minimal internal processing capabilities. Current systems now offer displays with more than a megabyte (1,024 x 1,024) of image memory and have considerable internal processing capability. Further improvements in the ability to efficiently handle the massive volumes of data generated by the latest generation of scanners in increasingly sophisticated manners are crucial to the continued advancement of the PET field.


Considerations in setting up a positron emission tomography center.

Clinically oriented imaging with position emission tomography (PET) has come of age. Given an adequate referral base and physician interest, a compelling argument can be made at all levels of the review process for setting up a PET program in a clinical setting. PET is expensive. It is obvious that the cost of running a PET service depends heavily on an institution's ability to obtain reasonable financing. Educational institutions have the opportunity to acquire special funding through a variety of sources. On the other hand, money can be expensive for private entrepreneurs. It appears that in the near future PET centers will probably remain at educational institutions or large well-financed community hospitals able to raise money at reasonable rates until reimbursement issues are better resolved. Finally, the future of clinical PET may hinge significantly on the ability of commercial radiopharmaceutical suppliers to provide regional fluorodeoxyglucose distribution. As an institutional program development, PET offers opportunities by providing unique clinical data aiding the referral pattern. PET may serve as a magnet for recruitment in many areas and may promote interdisciplinary cooperation. A clinical PET center serves both as a model for future and more widespread use of PET and as a training ground for medical personnel. Finally, the unique capabilities of PET may facilitate grant opportunities.


Positron emission tomography as a multi-institutional effort.

The consortium relationship at State University of New York at Buffalo School of Medicine and Biomedical Sciences have made it possible to establish in this community a multi-institutional effort to develop positron emission tomography (PET). The type of approach used and the modalities employed to generate community, university, and federal support are presented. The development of PET technology has led to a greater understanding between the various disciplines, and joint efforts have been made to establish pilot projects in a number of research protocols in the clinical applications that are currently available today. The consortium concept has led to early consideration by third-party carriers to consider reimbursement for those established PET procedures that can be applied clinically. Hopefully, with the passage of time and the maturation of a regional PET center, the concepts proposed might be used as models for other installations throughout the country.


The future of positron emission tomography in clinical medicine and the impact of drug regulation.

Positron emission tomography (PET) was initially developed as a research tool for evaluating normal and abnormal physiology. Subsequently, the potential clinical utility of PET was recognized, and several specific clinical indications have been defined. PET has been demonstrated to be clinically useful in evaluating certain disorders of the brain and heart. PET holds significant promise for use in the evaluation of psychiatric illness and in multiple aspects of evaluation of malignancy. A major limiting factor for the growth of clinical PET is the absence of policies for reimbursement by third-party payers. Although rubidium-82 chloride is approved by the Food and Drug Administration (FDA), the lack of FDA approval of fluorine-18 2-fluoro-2-deoxyglucose (FDG) is hampering reimbursement for PET studies. The jurisdiction of the FDA over cyclotron-produced PET radiopharmaceuticals synthesized and used on site is a matter of debate because these drugs are not introduced into interstate commerce and because these activities appear to be permissible under certain exemptions in the Federal Food, Drug, and Cosmetic Act relating to the practices of medicine and pharmacy. The jurisdictional authority of the FDA in regulating these radiopharmaceuticals would be established with certainty only through litigation, but no individual or organization has elected to challenge the FDA at this time. The Institute for Clinical PET (ICP) is developing a Drug Master File that can be used in support of site-specific New Drug Applications (NDAs) for cyclotron-produced radiopharmaceuticals by any organization desiring an NDA. The ICP is optimistic that this method of obtaining FDA-approval of FDG and other cyclotron-produced PET radiopharmaceuticals will be successful and beneficial to sites using PET clinically.


Behavioral states and their ontogeny: animal studies.

Despite numerous attempts in describing the many underlying events correlated with changes in behavioral states, the biological significance of state alternation remains unknown. There does not yet exist a satisfactory explanation for the biological need for such state changes, nor does there exist sufficient physiological evidence to explain the underlying processes leading to these state transitions. Nonetheless, the study of these ontogeny of behavioral states is important because it shows the progressive ability of the organism to integrate multiple neuronal systems. Available literature suggests that some rudimentary form of behavioral state is established in fetal life throughout the animal kingdom, although there is substantial difference in the degree and rate of development of organized behavioral states among the different animal species. Highly organized behavioral states that involve concurrence of many physiologic systems are present in the third trimester in the fetal lamb, while they are not seen until 2 to 3 weeks postnatally in the rat, rabbit, and cat. Subsequent maturation consists primarily of increased cycle length in all species. In addition, there is some evidence that a circadian rhythm may be superimposed on the ultradian rhythm of behavioral states in immature animals, but there is currently no information on the ontogenesis of this circadian rhythm. It is currently hypothesized that behavioral states cycling in the adult is generated by the interaction of multiple, anatomically distributed sets of neurons. Electrophysiological and pharmacological studies have suggested that both the cholinergic and aminergic neuronal systems play important roles in the maintenance of state cycling. Studies in the fetal lamb also support these proposed mechanisms in early development.(ABSTRACT TRUNCATED AT 250 WORDS)


Behavioral states and the peripartum period.

Fetal movements with their associated FHR accelerations, as well as the cyclic alternation between episodes of low and high FHR variability, particularly in late pregnancy, give a clear indication of the fetal rest-activity cycle. FHR variability changes during labor indicate that the rest-activity cycle continues even though perceived movements may diminish and fetal breathing may stop. Fetal behavioral states, known to be present by term and characterized by the concordant association of fetal movements, continue during labor. However, not all labors show evidence of fetal behavior despite a normal outcome, and the significance of this remains unknown. The influence of the fetal rest-activity cycle on FHR variability is such that recognition of behavioral cycles, when present, is essential for appropriate interpretation of the FHR during labor.


The effect of behavioral state on fetal metabolism and blood flow circulation.

As in postnatal life, behavioral states when evident in utero are also seen to influence the metabolic activity and/or circulation of several organ systems if not the global metabolic and circulatory activity of the fetus. In some instances this effect is organ specific as in the increased metabolic activity of the brain during the fetal REM state, which may account for the prominence of this state through the perinatal period and contribute to the brain's growth and development at this time. Generalized metabolic and circulatory effects may also be seen as associated with state-related changes in fetal biophysical activity or circulating vasoactive substances. Although the exact functions of sleep and sleep states are not yet known, their influence on the metabolic and circulatory activity of organ systems is seen to onset in early life, suggesting that a need for such may be just as important during early development as in later life.


Computed tomography of talocalcaneal coalition: imaging techniques.

The diagnosis of symptomatic talocalcaneal coalition requires an imaging study that demonstrates precise anatomic detail. Computed tomography affords the best method for the diagnosis. This essay reviews the computed tomographic anatomy of talocalcaneal coalitions in several projections and stresses the routine use of the angled coronal and direct sagittal projections.


Value of polydirectional tomography in the assessment of the postoperative spine after anterior decompression and vertebral body autografting.

With the growing number of orthopedic reconstructive spinal procedures, the use of bone grafting has steadily increased in the past decade. An understanding of the biology of bone grafting is essential for both the clinician and radiologist. Despite the advent of computed tomography and magnetic resonance imaging, conventional polydirectional tomography remains an important tool in the evaluation of vertebral body autografts. Trispiral or hypocycloidal tomography plays a valuable role in the assessment of bone graft fusion and possible complications, especially in the presence of metallic fixation devices. We present our imaging experience derived from 375 patients with cervical, thoracic, or lumbar anterior spinal fusion. True graft complications occurred in 27 patients (7%) and consisted of fracture (4%), malpositioning (3%), and infection (less than 1%).


The prevalence and significance of cyst-like changes at the cruciate ligament attachments in the knee.

Approximately 1% of the total population referred for magnetic resonance imaging (MRI) of the knee at our facility have cystic changes at or near the attachment of the anterior or posterior cruciate ligaments (ACL, PCL). Cases were collected prospectively from a group of 1710 consecutive knee MR examinations, and a retrospective study analyzed the typical appearance of these cysts and any associated findings. Although most of the cysts were an incidental finding, two were associated with significant adjacent marrow edema.


The metacarpal index--obsolete in Marfan syndrome!

28 patients with definite, probable or phenotypic Marfan syndrome underwent manual and computerised measurement of their metacarpal indices. Two methods were used from among the several variations quoted in the literature, one involving the average length/width of metacarpals 2-5 (method I), and the other dividing the sum of the lengths by the sum of the widths of these metacarpals (method II). The two methods are not mathematically identical, and a statistically significant difference was noted between them. Only 50% of the children in each group had elevated metacarpal indices, making it a time-consuming method that is indicative only of the phenotype and can be found in normal individuals. It should therefore be considered an obsolete measurement in Marfan syndrome.


Contrast-enhanced fat saturation magnetic resonance imaging for studying the pathophysiology of osteonecrosis of the hips.

We imaged 75 hips in 40 patients using fat saturation technique before and after intravenous injection of contrast (0.1 mmol/kg gadolinium diethylene triamine penta-acetic acid, Gd-DTPA). Eighteen hips in 11 patients were determined to be osteonecrotic, either by pathologic or clinical examination. In the osteonecrotic hips, three distinct patterns of enhancement were found: (I) focal area outlined by brightly enhancing rim (7 hips); (II) diffuse enhancement in the femoral head and neck extending into the femoral shaft (3 hips); and (III) a combination of patterns I and II (8 hips). Our data support the hypothesis that early nontraumatic osteonecrosis is associated with hyperemia and/or an increase in capillary permeability rather than acute devascularization, and that diffuse marrow edema is the initial finding in early nontraumatic osteonecrosis.


The skeleton in congenital, generalized lipodystrophy: evaluation using whole-body radiographic surveys, magnetic resonance imaging and technetium-99m bone scintigraphy.

Congenital generalized lipodystrophy (CGL) is a rare genetic disease characterized by the absence of body fat from birth. Focal bone lesions have also been reported, but their pathophysiology is poorly understood. To characterize skeletal abnormalities further in 3 patients with CGL, we employed whole-body radiographic skeletal surveys, magnetic resonance imaging (MRI, including gadolinium enhancement), and triple phase technetium-99m methylene diphosphonate bone scintigraphy. Radiographs showed numerous focal lesions within the long bones, as described in other reports. MRI showed that the entire marrow space of the long bones was abnormal and was characterized, at least in part, by the absence of marrow fat. Prolonged T1 and T2 times and marked gadolinium enhancement were observed in radiographically normal-appearing long bone. Radiographically lytic lesions occasionally demonstrated fluid-fluid levels on MRI and enhanced peripherally after gadolinium infusion. Bone scintigraphy findings such as periarticular hyperemia were relative subtle. We conclude that the appendicular skeleton of patients with CGL is diffusely abnormal and is predisposed to focal osteolysis and cyst formation.


Case report 728: Desmoplastic fibroma.

A 69-year-old woman with a 25-year history of recurrent sciatica presented with an expanding lytic lesion of the right side of the first sacral vertebra. Histological examination proved the lesion to be a DF. DF is usually diagnosed in young patients and is very rarely located in the spine and sacrum. The growth rate of the tumor was presumed to be very low because it had not progressed from radiological studies performed 9 years previously. The clinical, radiological, and pathological features of DF are described, and the differential diagnoses are discussed. The most difficult problem is to distinguish DF from a low-grade fibrosarcoma or chordoma.


Case report 745: Synovial lipoma arborescens.

A case is presented of lipoma arborescens of the knee with an atypical, sudden onset. Arthrography and ultrasound confirmed a synovially based lesion in the suprapatellar pouch. CT enabled a preoperative diagnosis of lipoma arborescens to be made, which was confirmed by surgical excision of a fronded fatty mass. Histological studies showed hyperplastic villi with mature adipose cells in the subsynovial layer. Resection of the synovium is considered curative, with only one case of recurrence after synovectomy having been reported [4].


Case report 746: Osteopetrosis.

Osteoporosis is a disorder characterized by osteoclastic dysfunction. The bones of afflicted patients become sclerotic and show modeling defects resulting in either a decrease or obliteration of the marrow cavity and resultant pancytopenia. Other clinical manifestations include bony deformities, cranial nerve palsies from bony overgrowth, pathological fractures, osteomyelitis, and hepatosplenomegaly secondary to extramedullary hematopoiesis. In the skull, the diploic space is usually decreased or obliterated. Absent or decreased marrow space is observed on plain films. On MRI, the marrow cavity very likely will be obliterated with low signal intensity on T1- and T2-weighted images. We report a case of osteopetrosis in which the diploic space is markedly increased, giving a hair-on-end appearance resembling thalassemia major. Perhaps some local factor within the diploic space prevented the expected osteoclastic dysfunction, allowing remodeling and expansion of the cranial vault.


Case report 747: Leiomyosarcoma of great saphenous vein.

Vena caval leiomyosarcomas are rare tumors; noncaval leiomyosarcomas are even less common and are rarely diagnosed preoperatively. We present a case of leiomyosarcoma of the great saphenous vein that was diagnosed by MRI based on its appearance and location. The presence of an intraluminal tumor in a vein on MRI should suggest the diagnosis of leiomyosarcoma of the vein, allowing definitive operative excision. With widespread use of MRI for indeterminate soft-tissue masses, we anticipate presurgical diagnosis of venous leiomyosarcoma will be made with increasing certainty and frequency.


Case report 748: Chondroblastoma of the femur with an aneurysmal bone cyst.

A case of chondroblastoma associated with an aneurysmal bone cyst has been described. The radiographic appearance of the lesion understandably reflects the combined features of both tumors. Up to one-half of all cases of aneurysmal bone cysts are found in association with other tumors, benign or malignant, and up to 15% of chondroblastomas are combined with an aneurysmal bone cyst (4).


Case report 750: Aspergillosis of the chest wall in an apparently immunocompetent host.

This is a case of aspergillosis of the bone and soft tissues of the chest wall in a (probably) immunocompetent host. The areas of involvement and different types of this disease are described. The A. flavus group, which presumably was responsible for this involvement of the chest wall, is very uncommon as a pathogen in humans.


Case report 751: Spindle cell lipoma causing marked bone erosion.

We present an unusual case of spindle cell lipoma of the foot which produced marked bone erosion. Spindle cell lipoma was initially described in the mid-1970s as having the characteristics of a lipoma with partial or total replacement of mature fat by collagen-forming spindle cells. This lesion is most commonly found in the subcutaneous tissue of the posterior neck and shoulder in men between 45 and 65 years of age.


Case report 752: Normal variant of the acromion simulating grade I acromioclavicular separation.

This case illustrates a developmental variant of the acromion resulting in apparent widening of the acromioclavicular joint space rather than discontinuity of the inferior cortices of the acromioclavicular joint. Had an axillary view not been obtained, an erroneous radiographic diagnosis of grade I acromioclavicular separation might have been suggested.


Dysplastic (atypical) nevi: significance and management.

The frequency of malignant melanoma is rising at an alarming rate. Familial dysplastic nevi have been shown to be markers for and perhaps even precursors of malignant melanoma. This paper addresses the clinical and histologic features of these lesions, the structural and functional abnormalities of the melanocytes present in dysplastic nevi, the systemic and genetic abnormalities seen in patients with the dysplastic nevus syndrome, and the risk of melanoma in persons with dysplastic nevi. Management of persons with dysplastic nevi should include stressing sunlight avoidance and self-examination, deciding which lesion(s) to surgically excise, a schedule of visits to the physician, the possible use of photography, and the need to individualize patient management.


Eosinophilia-myalgia syndrome: the aftermath.

We report here the long-term sequelae in 22 patients with L-tryptophan-induced eosinophilia-myalgia syndrome (EMS). The mean follow-up was 23 months (range, 5 to 40 months). Myalgia, rash, pruritus, edema, and respiratory symptoms often improved with the use of corticosteroids, but fatigue and weakness persisted in most cases. Other abnormalities that commonly persisted were arthralgia, muscle-cramping, peripheral neuropathy, and thickened skin. One patient had chronic pulmonary hypertension. These findings indicate that for most patients, EMS is a chronic disorder.


Infiltration during intravenous therapy in neonates: comparison of Teflon and Vialon catheters.

Infiltration is a frequent complication of intravenous therapy using peripheral venous lines in neonatal patients. In a randomized trial of two catheter materials, Vialon (Becton Dickinson) and Teflon (DuPont), we studied 19 putative risk factors for infiltration, including 11 infusates, in 772 peripheral venous lines in patients aged 1 to 67 days. The best-fit Cox regression model identified six significant predictors of infiltration (P less than .05): catheter material, age, anatomic insertion site, hyperalimentation, and use of furosemide and dopamine. For the subsample of patients weighing less than or equal to 1500 g, a second Cox regression model identified time spent inserting the catheter and the number of insertion attempts as additional significant predictors. These multivariate models showed that Vialon catheter material reduced the risk of infiltration by 18% (95% CI, 1% to 32% reduction) in the total sample and by 35% (95% CI, 15% to 50% reduction) in the higher risk low-weight (less than or equal to 1500 g) subsample.


Single lung transplantation: replacement therapy for end-stage lung disease.

Advances in immunosuppression and operative techniques have allowed single lung transplantation to become a viable treatment option at selected medical centers. We describe eight patients, all from the southeastern United States, who had single lung transplantation at Vanderbilt University Medical Center from March 1990 to June 1991. Their diagnoses represent a diverse set of diseases including idiopathic pulmonary fibrosis, primary pulmonary hypertension, emphysema, and pulmonary veno-occlusive disease. After thorough evaluation, the average waiting period to transplantation was 165 days. The posttransplantation periods were conspicuous for rejection, infection, and other complications. All of these recipients have either returned to an active life or are actively recuperating; this center's first single lung recipient has now survived 15 months. Our initial experience with single lung transplantation is encouraging, yet broader application requires that the paucity of donor organ availability be rectified.


Prevalence of olfactory dysfunction, hearing deficit, and cognitive dysfunction among elderly patients in a suburban family practice.

Olfactory and hearing senses diminish with age, and cognitive dysfunction increases. The association between sensory deficits and cognitive dysfunction has not been well studied. This paper presents the results of testing a group of 50 community-dwelling patients of a family physician who developed a computer-assisted comprehensive geriatric assessment program. Olfactory dysfunction was present in 39% of subjects, with 18% being unable to detect smoke. There was no correlation between olfactory dysfunction and cognitive dysfunction. Hearing deficit, however, was found in 10% of subjects, all of whom also had either an associated olfactory or cognitive dysfunction. This study demonstrates the high prevalence of olfactory and auditory dysfunction in an ambulatory geriatric population, with a possible association between hearing deficit and cognitive dysfunction. The problem of multiple sensory deficits should be addressed in any long-term management decisions regarding elderly patients.


Grip strength before and after carpal tunnel decompression.

We prospectively studied preoperative and postoperative grip and pinch strength in 21 patients having 30 consecutive median nerve decompressions for carpal tunnel syndrome. All procedures were done by one surgeon. Each hand operated on served as its own control and was studied by the same therapist preoperatively and at monthly intervals for 6 months after the procedure. An initial decline in both grip and pinch strength was noted in most hands during the first postoperative month. Eighty percent or more grip strength was regained in 65% of the hands at 2 months and in 81% at 3 or more months. In those hands (65%) that regained at least 100% of their preoperative grip strength at 3 or more months, there was an average increase in maximal grip of 56%, as compared with an average decrease of 20% in the remaining hands (35%).


Infected pressure sores: comparison of methods for bacterial identification.

Diagnosis of the bacterial component of pressure sores is notoriously difficult. We comparatively studied three methods of specimen collection from 72 pressure sores. Specimens taken by swab or by needle aspiration were compared with deep biopsy specimens as to diagnostic reliability. We found that swab specimens reflected surface colonization and that needle aspiration seemed to underestimate bacterial isolates as compared with deep tissue biopsy specimens. We recommend that antibiotics not be routinely used for treatment of colonization in pressure sores; in patients with sepsis, deep biopsy specimens can accurately diagnose infection.


Myasthenia gravis and HLA phenotypes in Jamaicans.

We determined HLA-antigen frequencies and corresponding relative risks (RR) in 30 Jamaicans with myasthenia gravis (MG) and 40 normal controls. Using a microcytotoxicity assay and commercially prepared typing trays, we found that the strongest HLA associations with MG in Jamaicans were with HLA-A2 (RR = 6.15), HLA-B8 (RR = 3.4), HLA-B13 (RR = 7.76), and DQw4 (RR = 3.8). After correction of the P value for the number of antigens tested, only HLA-A2 was statistically significantly increased in MG patients. There was a statistically significant negative association between MG and HLA-DR2, as well as HLA-A9 and -B5. No correlation was observed between HLA phenotype, thymic disease, clinical grades, or disease course. HLA-A2 and sex were independent risk factors for MG, female patients having a higher risk (RR = 5.8). Further studies using larger patient and control groups, locally derived typing sera, and DNA probe analysis are indicated.


Neuroanatomic/neuropathologic correlates in schizophrenia.

In the 1980s, numerous studies demonstrated neuropathologic changes in schizophrenia. Increased ventricle-brain ratios in schizophrenics have been reported. Birth-related trauma coupled with a genetic predisposition may be involved in the increased ventricle-brain ratios and in the development of some forms of the illness. Probable embryogenic anomalies in the hippocampus and other informational processing centers seem involved.


Infective endocarditis due to Neisseria sicca and associated with intravenous drug abuse.

Intravenous drug abusers are subject to infective endocarditis from unusual pathogens, including the saprophytic species of Neisseria, sometimes transmitted by needles contaminated with oral secretions. We have recently encountered such a case, in which a 37-year-old man with vegetations on the anterior leaflet of the tricuspid valve had blood cultures positive for N sicca. A history of intravenous drug abuse using needles contaminated with oral secretions should alert clinicians to the possibility of infective endocarditis due to saprophytic Neisseria species.


Malacological survey in the Bhumibol Reservoir, the first dam constructed in Thailand.

Twenty-five species of molluscs were found in a malacological survey in the Bhumibol Reservoir and in the Ping River in front of the Bhumibol Dam and its tributaries in April and August 1985. Among these species, Tricula aperta or Neotricula aperta, intermediate host of human schistosomes and Bithynia (Digoniostoma) siamensis goniomphalos and B. (D.) funiculata, the first intermediate host of human liver flukes, were not found. Although some of the intermediate hosts of mammalian schistosomes, Indoplanorbis exustus and Lymnaea (Radix) auricularia rubiginosa were found, none of them were positive for the parasitic infection. However, the malacological survey in the Bhumibol Reservoir revealed the existence of colonies of edible snails, Filopaludina (Filopaludina) doliaris, F. (F.) filosa and F. (Siamopaludina) martensi martensi along the shoreline of the reservoir. Thus, it is recommended that the local villagers collect them for household consumption or for sale. This practice would augment the food supply and also increase the income of the local villagers in the Bhumibol Reservoir area.


Prevalence of anti-HCV antibody in family members of anti-HCV-positive patients with acute and chronic liver disease.

Presence of circulating anti-hepatitis C antibody (anti-HCV) was screened in 201 Thai patients with acute and chronic liver disease who presented to Ramathibodi and Phya Thai Hospitals during 1984-1990. Of these, 29 patients (14.4%) were positive for anti-HCV. Circulating anti-HCV was determined in 92 family members (20 spouses, 72 household contacts) of these index cases and was detected in 5 contacts (2 spouses, 2 daughters and 1 mother) of 3 index cases. The overall prevalence of anti-HCV among the contacts was 5.4% (5/92) and it was higher in sexual partners (2/20, 10.0%) compared to other household contacts (3/72, 4.2%) but this was not statistically significant (p = 0.297). The anti-HCV-positive contacts were significantly older (mean +/- SD = 61.4 +/- 14.4) than the other contacts either comparing within the same families (26 +/- 16.5; p = 0.012) or all studied families (25.1 +/- 13.3; p = 0.006). One anti-HCV-positive contact had hepatocellular carcinoma, one had unexplained elevation of serum aminotransferase and the remaining 3 had no clinical or laboratory evidence of liver disease. All of the 3 index cases with anti-HCV-positive contacts, had chronic liver disease (2 cirrhosis, 1 chronic persistent hepatitis) and the prevalence of anti-HCV in these families (8/13, 61.5%) was significantly higher than the remaining 26 families (26/108, 24.1%) (p = 0.008). The results of this study suggest that sexual and other intrafamilial personal contact may be important for HCV transmission. Duration of close contact and family relationships appear to determine this mode of HCV transmission.


Adult longevity of certain mosquito species after larval and pupal exposure to sublethal concentration of an insect growth regulator, hexaflumuron.

Longevity of the adults of three vector species, Culex quinquefasciatus, Anopheles stephensi, and Aedes aegypti was drastically reduced when they were exposed at larval and pupal stages to sublethal concentrations of an insect growth regulator hexaflumuron. When the three species were exposed to 0.05 mg/l at the pupal stage, males and females of Cx. quinquefasciatus suffered a more shortened life span than other species. Among the females whose feeding activity was adversely affected by IGR treatment at the pupal stage, Ae. aegypti showed the minimum survival duration with LT50 of 2.74 days.


Laboratory evaluation of five pesticides for control of Leptotrombidium fletcheri (Acari: Trombiculidae).

Five pesticides were evaluated against laboratory colonies of Leptotrombidium fletcheri (Womersly and Heaslip) by the Pasteur pipet technique. The pesticides were dieldrin (LC50 = 3.6 ppm, LC99 = 18.2 ppm), bromopropylate (LC50 = 9.2 ppm, LC99 = 239.6 ppm), dicofol (LC50 = 27.8 ppm, LC99 = 118.1 ppm), fenthion (LC50 = 15.4 ppm, LC99 = 29.7 ppm), and malathion (LC50 = 84.7 ppm, LC99 = 313.9 ppm). Dieldrin was the most toxic. Dicofol was recommended for further evaluation in field trials.


Anopheles dirus size and fecundity: relationship to larval density and protein accumulation.

Anopheles dirus were reared at two different larval densities (100/pan and 400/pan) to produce two different size classes of adults. Both the wing length and fecundity of females from the two densities were significantly different (p less than 0.001). Adult size was related to larval density and protein accumulation during immature life. Egg production was also related to adult size. Consequently, larger field adults have the potential to live longer and produce more eggs. The smaller adult size associated with crowded larval development was apparently caused by space associated effect on feeding rather than by a shortage of food per se.


Cryptosporidium in 100 Australian children.

Over a consecutive 36 month period, 100 patients out of 6,980 (1.4%) from whom stool samples were examined had oocysts of Cryptosporidium detected on fecal microscopy. Three patients were receiving cytotoxic chemotherapy and adequate clinical information was available from 84 of the remainder. Fifty per cent of patients were aged 1 to 2 years, 29% were less than 12 months and the rest were more than 2 years of age. More than one-quarter of the patients were Australian Aborigines. Isolations of cryptosporidia were most prevalent in late summer, autumn and early winter. Most patients (89%) had diarrhea, more than 75% had vomiting and 44% were dehydrated, mostly to a mild degree. Other symptoms included fever (11%) and abdominal pain (11%). Ten percent of patients were apparently symptomless. Cryptosporidium sp. is the second most commonly identified intestinal parasite, after Giardia intestinalis, in fecal specimens examined in our children's hospital. The high rate of isolation in Aboriginal children emphasized the importance of enteric pathogens in this group and the role of inadequate hygiene in relation to diarrheal disease in young Aborigines.


Community-acquired pulmonary infection due to Chlamydia in tropical Queensland.

By using enzyme immunoassay and immunofluorescence antigen detection techniques on sputum specimens, four of 260 patients with pulmonary infection resident in tropical Queensland were found to be infected with Chlamydia. All four chlamydial infections were community-acquired and there was no history of close contact with birds by any of the four patients. One woman was deemed to be suffering with Chlamydia pneumonia, while the role of the organism in the pathogenesis of respiratory disease in the other three patients was indeterminate. At present, the incidence of pulmonary chlamydial infection in the population of tropical Queensland does not warrant routine testing, but investigations for these organisms should be undertaken in patients who present to their physicians with atypical pulmonary infection or whose clinical conditions are refractory to penicillin/ampicillin therapy.


Prevalence of complement fixing antibody to Mycoplasma pneumoniae in Thai children.

The prevalence of antibodies to Mycoplasma pneumoniae was determined in normal Thai children by means of complement fixation. There were 445 children (243 boys and 202 girls) of different ages, ranging from newborn to 15 years. The lowest frequency of complement-fixing antibody was found in children age 1-3 months, and highest in children age 6-10 years which corresponds to the age distribution of symptomatic M. pneumoniae infection. The lowest and highest titers measured were less than 1:8 and 1:512 respectively. The prevalence of complement fixing antibody of titers more than or equal to 1:8, 1:32, 1:64 and 1:128 were 61.3, 31.7, 25.4 and 10.3 per cent of total children, respectively. Among children less than one month old, the frequency of complement fixing antibody of titers greater than or equal to 1:32 was 12.2 per cent and decreased to 1.3 per cent among children from the age 1-3 months. This decrease probably represented the disappearance of maternal antibody over this period. An increase in both the frequency and the geometric mean titer was seen thereafter. The peak frequency of high titers (greater than or equal to 1:32), 81.1 per cent, occurred in children 6-10 year of age. Paired sera were obtained from 72 children with high titers of greater than or equal to 1:64, 9.7 per cent had four fold changes of titer which indicated recent infection.(ABSTRACT TRUNCATED AT 250 WORDS)


Species-differences in the pH-activity pattern of acid phosphatase in the family Enterobacteriaceae.

Nonspecific phosphatase activities were surveyed comparing major species of the family Enterobacteriaceae. The strains were subjected to a whole cell assay system with paranitrophenyl phosphate as substrate over a wide pH range and with a standardized number of bacterial cells. The overall results suggest that the general shape of the pH activity curve and the location of peaks (pH optimum) can be employed as a supplementary criterion to characterize species of Enterobacteriaceae.


Prevalence of varicella-zoster virus infection in Singapore.

The incidence of chickenpox in Singapore has been increasing since 1984. A seroepidemiological survey was conducted in 1989-90 to determine the prevalence of varicella-zoster virus-specific IgG antibody in the healthy population in Singapore aged from 6 months to over 45 years. Overall, 42.8% of 500 samples assayed qualitatively by the ELISA method were positive, with less than one fifth of those aged under 15 years and less than half of the 15-24 year olds possessing antibody to the virus. However, antibody prevalence increased markedly to between 86% and 98% in those over 25 years of age. No significant sex or ethnic difference was noted. The survey confirmed the low herd immunity and the higher susceptibility of the young adult population to varicella infection in a tropical city compared to that of temperate countries.


Infants born to HIV infected mothers.

Eighty infants born to HIV-infected mothers were studied prospectively at Children's Hospital, Bangkok, Thailand from February 1989 to June 1991. The risk factors for acquisition of HIV infection were analyzed in 33 mothers (41.25%) including a history of being sex workers and having husbands who had extramarital sexual contact (22.5% each), having other sexually transmitted diseases (20.0%) and being IV drug users (6.25%). All infants appeared clinically normal without congenital anomaly, 22.5% (18 of 80) were of low birth weight with 91.43% (64 of 70) positive for HIV-antibody at birth. On follow up 56.25% (9 of 16) seroreversed during age 6 to 15 months, whereas 5 infants who were HIV-Ab negative at birth remained Ab negative on follow up for up to 15 months. One of 49 infants who attended the follow up clinic had been suffering from recurrent diarrhea, failure to thrive and encephalopathy since 9 months old; she weighed 6.7 kg at 15 months of age and remained positive for HIV-Ab.


Thrombocytopenia in malaria.

The relationship between platelet counts and platelet bound (direct) or platelet directed (indirect) serum antibody concentrations was studied in 17 patients with Plasmodium falciparum malaria and 12 patients with P. vivax malaria. Platelet counts rose with recovery from infection from 196 +/- 84 x 10(9)/l (mean +/- SD) and 195 +/- 34 x 10(9)/l to 319 +/- 99 and 283 +/- 62 x 10(9)/l respectively (p less than 0.002), but there was no relationship between either absolute platelet count or changes in counts and either indirect or direct platelet antibody levels. These findings suggest that a non-immunologically mediated mechanism is involved in the pathogenesis of thrombocytopenia in malaria.


Effect of mefloquine on electrocardiographic changes in uncomplicated falciparum malaria patients.

Asymptomatic sinus bradycardia and sinus arrhythmia have been noted in malarial patients receiving mefloquine. The present study was designed to assess the effect of mefloquine on electrocardiogram in malarial patients. The study was carried out in 102 acute uncomplicated falciparum malarial patients who were treated with mefloquine 750 mg and 1,250 mg regimens and 18 healthy male volunteers receiving 750 mg of mefloquine. Electrocardiogram was performed at intervals after mefloquine administration for a period of 42 days. PR, QRS, QT, QTc, RR interval and cardiac arrhythmia were measured and read by EKG-analyser with confirmation by a cardiologist. Sinus bradycardia and sinus arrhythmia were found in 61.8% and 45.1%, respectively during the first week after treatment. The patients' heart rate decreased significantly on day 6 after mefloquine administration when compared to day 0. The occurrence of sinus bradycardia and sinus arrhythmia were significantly higher in malarial patients when compared with findings in healthy subjects of the same age group. It is unlikely that these changes are associated with mefloquine concentration as mefloquine peaks around 12-24 hours after administration. There were no significant changes in PR-interval, QRS-interval and QTc interval on the electrocardiogram. The findings in this study suggest that cardiotoxicity from mefloquine is unlikely. Bradycardia may be the result of autonomic control modulation after resolution of high fever.


Comparative trial on the response of Plasmodium falciparum to halofantrine and mefloquine in Trat Province, eastern Thailand.

With the appearance of strains of Plasmodium falciparum in the Trat Province, eastern Thailand, reported to have developed resistance to mefloquine there is a need for an alternative drug. This comparative trial with mefloquine and halofantrine has demonstrated extremely low cure rates with both drugs (33.3% and 28.13% respectively), cross-resistance is suggested.


Comparison of effects of pyronaridine, amodiaquine, mefloquine and qinghaosu on rodent malaria.

Blood schizontocidal effect of antimalarials were compared by 4-day suppressive test with an extended observation period of 31 days. On a drug-sensitive Plasmodium berghei ANKA strain, pyronaridine (PND) exhibited the best effect, followed by amodiaquine (ADQ), mefloquine (MFQ), and qinghaosu (QHS). On a moderately chloroquine-resistant P. berghei NS line, the order of effects was the same, PND greater than ADQ greater than MFQ greater than QHS. On a highly pyronaridine-resistant P. berghei RP line, ADQ, MFQ and QHS showed cross resistance with PND.


Erythrocyte glucose-6-phosphate dehydrogenase and pyruvate kinase activities in hemoglobin H disease.

Erythrocyte glucose-6-phosphate dehydrogenase (G6PD) and pyruvate kinase (PK) activities were studied in hemoglobin H (HbH) patients by spectrophotometric method, cytochemical method and the methemoglobin reduction (MR) test for the detection of heterozygous G6PD deficiency. G6PD deficiency was found in 7 of 64 cases (10.9%), including 3 cases of genotype alpha 1/alpha 2 and 4 cases of genotype alpha 1/CS. None of the HbH patients was found to be PK-deficient. Spectrophotometrically determined G6PD and PK activities were significantly higher in HbH patients than in normals (p less than 0.001), whereas the MR test yielded a significantly lower percentage of residual methemoglobin in HbH patients than in normals (p less than 0.05). All three methods were efficient in the detection of hemizygous G6PD deficiency in HbH patients, but not in G6PD-deficient females.


Studies on the use of cobalt-60 gamma irradiation to control infectivity of Clonorchis sinensis metacercariae.

The purpose of the present study was to observe the survival and development of Clonorchis sinensis metacercariae in their final hosts after Cobalt-60 gamma irradiation of isolated metacercariae or the parasite in fish. Guinea pigs or albino rats were orally infected with irradiated metacercariae by gavage. Bioassay, fecal examination for ova, and necropsy of infected animals, were the methods used for the estimation of minimum effective dose of gamma irradiation to control infectivity of the metacercariae. Results showed that the minimum effective irradiation dose for isolated metacercariae was 0.05 kGy. The LD50 of the irradiation dose for metacercariae in fish was 0.05 kGy, and the minimum effective dose was 0.15 kGy. No significant difference in radiation susceptibility to Co-60 gamma irradiation was found among C. sinensis metacercariae in fishes collected at different localities in northern, middle or southern parts of China. The present finding suggests that irradiation of fish by 0.15 kGy could control infectivity of C. Sinensis metacercariae and thus be adopted as a control measure in preventing infections.


Comparison of cysticercus extract, cyst fluid and Taenia saginata extract for use in ELISA for serodiagnosis of neurocysticercosis.

Cysticercus cellulosae extract (CS), cyst fluid (CF), and an extract of Taenia saginata adult worm (TS) were evaluated for use in an enzyme-linked immunosorbent assay (ELISA) for serodiagnosis of human neurocysticercosis in Thai patients. ELISA sensitivity was found to be 78.13%, 81.25% and 62.50%, respectively. False positivity was 6.66% with CS and 0% with other antigens. CF gave positivity with a pooled visceral gnathostomiasis serum and 3 of 10 (30%) of angiostrongyliasis sera. CS produced weakly positive ELISA with pooled opisthorchiasis and visceral gnathostomiasis sera. TS gave weak positive ELISA with a pooled opisthorchiasis serum. It was concluded that CF was the best antigen for use in ELISA for serodiagnosis of human neurocysticercosis.


Prevalence of Enterobius vermicularis amongst adults living in hostels by six successive day examination.

The prevalence of Enterobius vermicularis in four groups of adults, all trainee public health inspectors or public health nurses, aged 18-35 years and all living in hostels on campus was studied. The modified scotch tape technique was used and the subjects were taught to do the examination on themselves to detect the presence of eggs over a period of 6 successive mornings. Each was given an elaborately illustrated diagram on how and when to take the samples and given demonstration in groups. The samples were examined by trained people. Most of the subjects took samples on 6 consecutive days. Of the 119 subjects who returned samples, the overall prevalence of E. vermicularis was 9.2% and this was thought to be high for this particular age group. This was due to the higher prevalence (19.4%) in one group, whereas in the others the range was 3.5-8.0%. Based on the samples returned on the first day none of the subjects were detected as having the infection. After examination on 3 successive days (109 subjects) 10.1% were found to be infected (chi 2 = 10.704; d. f. = 1) and after examination on 6 successive days (72 subjects) 13.9% were found to be infected (chi 2 = 3.026; d. f. = 1). There was no significance between examination over 3 successive days and 6 consecutive days (chi 2 = 0.296; d. f. = 1). There was no difference in the prevalence between males and females.(ABSTRACT TRUNCATED AT 250 WORDS)


Diversity of complement-mediated immune reaction to Trypanosoma gambiense.

Intact and papain-treated Trypanosoma gambiense clone populations, each expressing special antigens on their cell surfaces, were mixed with rabbit antiserum in the presence of complement. Two distinct types of immune reaction between trypanosomes and antisera were observed: clumping followed by dissociation (CD) and inhibition of aggregation (IA). Special antigens on the cell surface of trypanosomes exposed after papain digestion are implicated in both types of immune reaction. IA was considered to be more effective as an immunological response which would allow the infected host to clear the pathogen without any obstruction of capillaries and impairment of blood flow caused by clumping masses of trypanosomes.


Induction of intestinal lesions in rabbits with Koyan and Baling strains of Schistosoma malayensis Sp N.

Schistosoma malayensis Sp N is a putative new species of schistosome discovered in Peninsular Malaysia in 1973. This paper comprises the first report on the detailed gastrointestinal pathology present in rabbits infected with strains of the parasite. Two different strains of schistosome--the Baling and Koyan strains--from two different ecosystems were used to infect inbred rabbits and the resulting pathophysiology was studied. Our results showed that the Baling strain of S. malayensis was more virulent than the Koyan strain and produced nodular, segmental circumferential lesions and large bilharziomas measuring 1-7 cm in diameter in the distal jejunum, ileum and the ileo-caecal junction. The findings indicate that the Baling strain of S. malayensis was more pathogenic for rabbits as compared with the Koyan strain--in relation to the gross pathology of the gut and the tissue egg load. Earlier reports have shown that rabbits infected with S. japonicum induces significant intestinal lesions in rabbits (Cheever et al, 1980 a,b) but these animals are refractory to infection with S. mekongi (Byram and Lichtenberg, 1980). Our studies show that the two strains of S. malayensis adapted well in rabbits. It is also established that in rabbits, the virulence of the Baling strain of S. malayensis is greater than that of S. mekongi and approximates that of S. japonicum.


Quantitative internal dens morphology.

Recent work has demonstrated the highly variable and unpredictable external dimensions of the dens (odontoid process). No data have been available regarding internal dimensions. Quantitative computed tomography analysis of 120 axis vertebrae allowed nondestructive measurement of external and internal dens dimensions. The external computed tomography measurements correlated well with caliper-derived data. Minimum internal dens dimensions and cortical thicknesses in the sagittal and transverse planes are reported. Some axis vertebrae may not be amenable to internal fixation of type II dens fractures. Preoperative planning should include quantitative computed tomography analysis of the dens.


Acute normovolemic hemodilution combined with hypotensive anesthesia and other techniques to avoid homologous transfusion in spinal fusion surgery.

To avoid homologous transfusion in spinal fusion surgery, acute normovolemic hemodilution was combined with controlled hypotensive anesthesia. Patients were kept hemodiluted, not only during surgery, but also after surgery by delaying transfusion until the next morning or later. Transfusion decisions were made by clinical judgment rather than by preset value (ie, 10 g/dl). Other techniques used in this protocol were preoperative autologous blood donation and intraoperative salvage of shed blood. Only 4 of 119 patients (3.4%) required homologous blood, compared to 25 of 29 patients (86%) in 1982, at which time none of these techniques were used. The average hemoglobin on the seventh postoperative day was similar in both groups; 11.5 g/dl in the current series compared to 11.1 g/dl in the 1982 series.


Changes in endplate vascularity after an outer anulus tear in the sheep.

In 31 2-year-old sheep, a 5-mm deep cut was made parallel to the end plates in the left anterolateral anulus fibrosus of 3 randomly selected lumbar intervertebral discs. At 2 months, the area of the end plate occupied by blood vessels on the left (operated) side had increased significantly (P less than 0.05) in the cranial end plate to 9.94%, and to 9.39% in the caudal end plate, compared with nonoperated values of 5.17% (cranial) and 5.87% (caudal). One year after operation, these elevated values had diminished significantly (P less than 0.05) to 7.92% (cranial) and 7.13% (caudal), and continued to decline progressively to 7.48% (cranial) and 6.88% (caudal) by 2 years. In contrast, no significant differences were found on the right (nonoperated) side of the discs. Thus, there was an early proliferation of vascular channels in the end plate in the vicinity of the experimental anular lesion, but not on the nonoperated side of the same disc. Thereafter, the end plate vascularity progressively diminished toward a normal level.


A reduction-fixation system for unstable thoracolumbar burst fractures.

Thirty-three patients with unstable burst fractures of the lower thoracic and lumbar spine were treated with a reduction-fixation system. The new system is used both as a reduction and a fixation device for disorders of the lower thoracic and lumbar spine. In treatment of spinal fractures, it provides symmetric lordotic distraction to obtain the best possible reduction of intracanal fragments, and rigidly stabilizes the fractured vertebra while involving the minimum number of segments. All patients had a minimum follow-up of 24 months. Most patients in this series had a near-anatomic reduction of all three columns in the involved segment. The "indirect" neurologic decompression was successful in cases treated early after injury. The fixation was rigid enough to allow early mobilization and rehabilitation in a light orthosis within 1 week after surgery, and there was minimal loss of reduction during the follow-up period. The complications were minor. The reduction-fixation system achieved the surgical goals of posterior instrumentation for treatment of unstable thoracolumbar burst fractures.


Morphometric characteristics of pedicles of the immature spine.

The morphometric characteristics of pedicles from T12 to S1 were measured from a review of 203 computerized tomographic scans of children 3 to 20 years of age. The pedicles of the lower lumbar spine (L4, L5, and S1) reached transverse extracortical pedicle diameters of 1 cm by the time the child reached 7 years of age. The pedicles of the upper lumbar spine (T12, L1, L2, and L3) did not reach similar size until the child reached 12 years of age. The data from this study suggest pedicular screw insertion, especially of the L5 and S1 vertebrae, is technically possible in young children.


Pitfalls of pedicle screw fixation in the sacrum. A cadaver model.

Five male cadavers were used to evaluate anatomically structures at risk using sacral pedicle screw fixation. Risk was defined as the likelihood of penetration by K-wires placed through the pedicles and cortices at the S1, S2, and S3 levels. A scale based on the distance from the wire to the vital structure was developed to quantify risk. Instrument insertion techniques were classified as direct and lateral. The direct technique at S1 placed the left common iliac vein and the sympathetic chain at high risk. The sympathetic chain was also at high risk at the S2 and S3 levels. The lateral technique placed the lumbosacral trunk at high risk at the S1 level, as well as the S1 nerve root with screw placement at the S2 level. Anterior cortical penetration during sacral pedicle screw fixation places anatomic structures at variable risk depending on the technique used.


A universal model of the lumbar back muscles in the upright position.

A model of the lumbar back muscles was constructed incorporating 49 fascicles of the lumbar erector spinae and multifidus. The attachment sites and sizes of fascicles were based on previous anatomic studies, and the fascicles were modeled on radiographs of nine normal volunteers in the upright position. Calculations revealed that the thoracic fibers of the lumbar erector spinae contribute 50% of the total extensor moment exerted on L4 and L5; multifidus contributes some 20%; and the remainder is exerted by the lumbar fibers of erector spinae. At upper lumbar levels, the thoracic fibers of the lumbar erector spinae contribute between 70% and 86% of the total extensor moment. In the upright posture, the lumbar back muscles exert a net posterior shear force on segments L1 to L4, but exert an anterior shear force on L5. Collectively, all the back muscles exert large compression forces on all segments. A force coefficient of 46 Ncm-2 was determined to apply for the back muscles. These results have a bearing on the appreciation of the effects on the back muscles of surgery and physiotherapy.


Effect of instructions on isokinetic trunk strength testing variability, reliability, absolute value, and predictive validity.

Although isokinetic strength testing has been in use for more than two decades, and numerous studies have addressed isokinetic performance of the lumbar spine, the effect of instructions on isokinetic trunk strength has not been studied. In a sample of 30 healthy women, this study examined the effect of "high-demand" instructions on lumbar strength performance. High-demand instructions were found to have a substantial positive effect on performance variability, reliability, absolute magnitude, and validity. Under these conditions, isokinetic trunk strength was found to be predictive of performance in a frequent lifting-lowering task.


Serial changes observed by magnetic resonance imaging in the intervertebral disc after chemonucleolysis. A consideration of the mechanism of chemonucleolysis.

Changes in the intervertebral disc after chemonucleolysis in 26 patients were observed by magnetic resonance imaging for 1 year, and from the results a mechanism for chemonucleolysis was considered. A reduction in size of the herniation was not recognized 2 weeks after treatment, when chymopapain had caused necrosis of the disc, but began after 4 weeks, when regeneration of the disc had occurred. The herniation was further reduced after 3 months, and the disc had become fibrocartilaginous in a cicatricial process. Marked decrease in disc signal was observed after 2 weeks, and never recovered. From these facts, it is considered that chymopapain might never cause primary diminution of disc herniation, and any reduction of herniation that occurs is due to the effects of a secondary cicatricial contraction.


Effects of compression on physiologic integrity of the spinal cord, on circulation, and clinical status in four different directions of compression: posterior, anterior, circumferential, and lateral.

The authors investigated the effects of focal compression on physiologic integrity; somatosensory evoked potentials, neurogenic motor evoked potentials and spine-to-spine potentials, on spinal cord circulation and clinical status in four different type of compression; posterior, anterior, circumferential, and lateral in 31 pigs. Spine-to-spine potentials degraded earlier in amplitude than somatosensory evoked and motor evoked potentials regardless of direction of compression. The first lost potential was the somatosensory evoked one during posterior, circumferential, and lateral compression and motor evoked potentials during anterior compression. Somatosensory evoked potential was the only wave to detect the side of lateral compression. Following release of compression somatosensory evoked potentials and motor evoked potentials returned almost to 100% in amplitude, whereas spine-to-spine potentials recovered to approximately 50%. At that time all animals showed grossly normal motion in hind-limb, therefore spine-to-spine potentials might be too sensitive to motor function. Spine-to-spine potentials should contain more tracts than either somatosensory evoked potentials or motor evoked potentials. Somatosensory evoked potentials probably show more posterior part, whereas motor evoked potentials do more of the anterior part of the spinal cord. The spinal cord revealed a complete ischemia regardless of direction of compression when at least one potential was gone, however it regained the shape and perfusion following release of compression although there were some hemorrhagic contusions remaining. These suggest that ischemic changes may play some part in degradation of potentials, however it does not influence much the recovery following release of compression because it regains quickly. The final recovery depends on the complication.


Spinal cord tissue pressure during spinal cord distraction in dogs.

Spinal column distraction is a known cause of spinal cord injury. Laplace's law predicts that cord interstitial pressure will elevate during spinal cord distraction. To determine the significance of the Laplace predictions a series of in vitro and in vivo experiments examining spinal cord distraction were performed. In vitro experiments were carried out on 10 dog spinal cords in a specially designed distraction apparatus. These experiments verified the Laplace's law demonstrating a close correlation (R(avg) = 0.99) between the tension applied to the cord, and cord interstitial pressure. Cord interstitial pressure strain (elongation) curves show that initial elongation is accompanied by negligible elevations of cord interstitial pressure; the final 20% elongation being responsible for 80% of the elevation in cord interstitial pressure. In vivo experiments were carried out on five beta-blocked dogs. Significant elevations in cord interstitial pressure were obtained during stepwise spinal column distraction. Spinal cord blood flow and somatosensory evoked potentials were well maintained during distraction until cord interstitial pressure reached 47 mm Hg. At this point a simultaneous fall in spinal cord blood flow and somatosensory evoked potentials was noted. Release of the distracting force resulted in return of spinal cord blood flow, somatosensory evoked potentials, and cord interstitial pressure to baseline. The authors conclude that significant elevations in cord interstitial pressure occur with spinal cord distraction and that these cord interstitial pressure elevations are associated with a reversible ischemic response in the cord.


Biomechanical analysis of lumbosacral fixation.

Flexion testing was performed until failure on 66 lumbosacral bovine spinal segments comparing ten different lumbosacral instrumentation techniques. Maximum flexion moment at failure, flexural stiffness, and maximum angulation of the lumbosacral joint at failure were determined as well as strain measurements across the anterior aspect of the lumbosacral intervertebral disc using an extensometer. The maximum moment at failure was significantly greater for the only two devices that extended fixation into the ilium anterior to the projected image of the middle osteoligamentous column: ISOLA Galveston and ISOLA iliac screws (F = 12.2, P less than 0.001). The maximum stiffness at failure reinforced these findings (F = 23.7, P less than 0.001). A second subset of stability showed the advantages of S2 pedicle fixation by increasing the flexural lever arm (Cotrel-Dubousset butterfly plate, and Cotrel-Dubousset Chopin block, P less than 0.05). This exhaustive in vitro biomechanical study introduces the concept of a pivot point at the lumbosacral joint at the intersection of the middle osteoligamentous column (sagittal plane) and the lumbosacral intervertebral disc (transverse plane). A spinal surgeon can increase the stability of lumbosacral instrumentation by extending fixation through the anterior sacral cortex (Steffee plate group with pedicle screws that medially converge in a triangular fashion). A means of enhancing this fixation was to achieve more inferior purchase by extending the fixation down to the S2 pedicle (Cotrel-Dubousset Chopin and Cotrel-Dubousset butterfly groups). However, the best fixation was achieved by obtaining purchase between the iliac cortices down into the superior acetabular bone.(ABSTRACT TRUNCATED AT 250 WORDS)


Prevalence of scoliosis in neurofibromatosis.

Experience in a comprehensive, multispecialty neurofibromatosis clinic leads the authors to suggest that the association of spinal deformity with neurofibromatosis is less frequent than usually assumed. Previously reported statistics may be partly attributed to preselection of patients seen by spinal surgeons, and to the predominant referral of patients having severe manifestations of neurofibromatosis. A diagnosis of neurofibromatosis 1, based on National Institutes of Health criteria, is confirmed for two hundred twenty patients at the clinic. Twenty-three of these patients have structural scoliosis. Nine patients have idiopathic type curves, eight have dystrophic scoliosis, four have dystrophic kyphoscoliosis, and two have dystrophic lordoscoliosis. The authors believe that 10% is representative of the true prevalence of spinal deformity in an otherwise unselected cross section of neurofibromatosis patients.


Incidence of deep vein thrombosis in major adult spinal surgery.

Deep vein thrombosis and pulmonary embolus are well known complications of lengthy orthopaedic procedures. Historically spine surgery has been associated with few thrombotic complications. Recent widespread use of instrumentation in adult cases led to concern regarding the incidence of deep vein thrombosis and pulmonary embolus. Forty-one patients underwent posterior spinal procedures using either pedicular or segmental instrumentation. One day before discharge all patients underwent noninvasive testing using color duplex Doppler imaging to rule out deep vein thrombosis. Six patients were noted to have tests results compatible with deep vein thrombosis. The incidence of deep vein thrombosis during this study (14%) reveals a group of patients who would have been discharged with ongoing thrombosis and potential pulmonary embolism.


Cotrel-Dubousset instrumentation in idiopathic scoliosis.

Although well accepted in the patient undergoing Harrington instrumentation, the validity of King's criteria in patients undergoing correction of idiopathic scoliosis using the Cotrel-Dubousset system has been questioned. The cases of 64 patients with Type II (N = 40) and Type III (N = 24) idiopathic scoliosis treated with Cotrel-Dubousset instrumentation were reviewed. The average curve correction for Type II spinal curvature was 69.4% after surgery and 57.8% at follow-up examination. Decompensation was evident in 40% of the curves that were fused beyond the stable vertebra. However, the patients were only aware of their trunk decompensation if it was larger than 10 mm, and this was found in 35% of the patients. Decompensation occurred in 60% of those that were fused short of or to the stable vertebra. Only 42% of this group were aware of their decompensation. Decompensation was measured to the left of the spine in all patients. The difference between the subgroups based on the choice of distal fusion levels was not statistically significant (P greater than 0.05). The average curve correction for Type III scoliosis was 62.9% after surgery and 54.6% at the time of follow-up examination. There was no correlation between caudal fusion levels and the incidence of decompensation with Type III curves. It was concluded that there was no statistically significant relationship between choice of distal fusion level and the amount of decompensation, thereby indicating that the use of King's criteria for the selection of fusion levels in patients undergoing correction of idiopathic scoliosis using the Cotrel-Dubousset instrumentation may not be useful.


Scoliosis correction by Cotrel-Dubousset instrumentation. The effect of derotation and three dimensional correction.

In 30 patients undergoing Cotrel-Dubousset instrumentation, computerized tomography was performed before and after surgery. The RAsag-angle was measured for each vertebral level. Coronal and sagittal translation were evaluated in the same computerized tomographic scans by means of a new method. Based on the hooks used, various sections of the spine were defined. In these sections relative rotation as well as relative sagittal and frontal translation were calculated by an algorithm comparing the most severely rotated or translated vertebra with the mean value of both end vertebrae. Significant correction of rotation did not occur in any of these sections. A significant increase of kyphosis, however, could be demonstrated in all thoracic sections. Above the second intermediate hook combined correction of all three parameters was achieved. Below this hook correction occurred almost independently in the frontal and sagittal planes.


Results of spinal instrumentation of adolescent idiopathic scoliosis by King type.

The purpose of this study is to determine the usefulness of the King classification in predicting decompensation in adolescent idiopathic scoliosis. Fifty-one patients were reviewed with a mean follow-up of 25 months. Five patients had Type 1 adolescent idiopathic scoliosis: four were treated with Zielke/Cotrel-Dubousset instrumentation or Zielke instrumentation alone. Correction was greater than 51% in these cases and there was no decompensation. Twenty-three patients had Type II scoliosis. Nineteen of whom were treated with Cotrel-Dubousset instrumentation; 3 with Zielke and Cotrel-Dubousset instrumentation, and 1 with Zielke. The best correction occurred with anterior/posterior instrumentation. Decompensation occurred in 9 patients, all of whom were treated with Cotrel-Dubousset instrumentation alone. Fourteen patients had Type III scoliosis. All were treated with Cotrel-Dubousset instrumentation with correction of 65%. Decompensation occurred in 4 patients, all of whom were fused to or beyond the stable vertebra. Four patients had Type IV scoliosis; all were fused short of the stable vertebra with Cotrel-Dubousset instrumentation, resulting in correction of 52% and no decompensation. Five patients had Type V instrumentation; four were treated with Cotrel-Dubousset instrumentation and 1 with Zielke. There was no relationship between level of fusion and decompensation. Based on this study, the authors contend that the King classification is a valuable tool in the selection of type of instrumentation and fusion level.


Preventing decompensation in King type II curves treated with Cotrel-Dubousset instrumentation. Strict guidelines for selective thoracic fusion.

Between 1985 and 1988, 50 adolescent idiopathic scoliosis patients with either King Type II (n = 19) or III (n = 31) curves were treated with Cotrel-Dubousset instrumentation and had a minimum of 2-year follow-up. Five of these patients had early postoperative decompensation, and have provided important lessons for the future prevention and treatment of these imbalances. Most problematic was distinguishing between King Type II and double major curve patterns. Proper identification of King Type II curves, which may be successfully treated with selective thoracic fusion, requires careful analysis of the standing preoperative coronal radiograph as well as the side benders. Thus, we now define Type II curves based on the differential between the thoracic and lumbar curve magnitude, apical vertebral deviation from the midline, and apical vertebral rotation on the standing coronal radiograph in addition to a positive flexibility index.


Lumbar curve response in type II idiopathic scoliosis after posterior instrumentation of the thoracic curve.

Twenty-four patients with King Type II scoliosis were retrospectively studied to determine if preoperative assessment of lumbar curve flexibility was predictive of postoperative spinal balance. All patients had preoperative lumbar curves exceeding 40 degrees and all underwent selective thoracic fusion with Cotrel-Dubousset or Texas Scottish Rite Hospital instrumentation. The lumbar curves corrected 73% on preoperative bend radiographs. Despite this significant flexibility, the lumbar curves remained larger after surgery than the instrumented thoracic curves and spinal imbalance occurred. This finding was due, in part, to postoperative persistence of obliquity between L4 and the pelvis. When using Cotrel-Dubousset or Texas Scottish Rite Hospital instrumentation, preoperative assessment of the large lumbar curve's flexibility is not particularly helpful in predicting its response to selective thoracic fusion, especially regarding whether postoperative imbalance may occur.


Thoracolumbar osteotomy for postsurgical sagittal imbalance.

A prospective study of 12 patients with sagittal plane imbalance after multiple surgeries for scoliosis is reported. Reconstruction was attempted by posterior thoracolumbar junction osteotomy. Eighty-seven degrees of thoracic kyphosis (ending at L3) was improved to forty-one degrees (ending at T12). Lumbar lordosis was increased from 21 to 30 degrees, beginning at L1 afterward (L3 before). 8.7 cm posterior displacement of the sagittal weight-bearing axis was achieved. No permanent complications ensued. The procedure, without anterior surgery, corrects the deformity at the apical area. Cotrel-Dubousset instrumentation secured correction and fixation.