FALCON systematically interrogates free fatty acid biology and identifies a novel mediator of lipotoxicity

Cellular exposure to free fatty acids (FFAs) is implicated in the pathogenesis of obesity-associated diseases. However, there are no scalable approaches to comprehensively assess the diverse FFAs circulating in human plasma. Furthermore, assessing how FFA-mediated processes interact with genetic risk for disease remains elusive. Here, we report the design and implementation of fatty acid library for comprehensive ontologies (FALCON), an unbiased, scalable, and multimodal interrogation of 61 structurally diverse FFAs. We identified a subset of lipotoxic monounsaturated fatty acids associated with decreased membrane fluidity. Furthermore, we prioritized genes that reflect the combined effects of harmful FFA exposure and genetic risk for type 2 diabetes (T2D). We found that c-MAF-inducing protein (CMIP) protects cells from FFA exposure by modulating Akt signaling. In sum, FALCON empowers the study of fundamental FFA biology and offers an integrative approach to identify much needed targets for diverse diseases associated with disordered FFA metabolism.

FALCON systematically interrogates free fatty acid biology and identifies a novel mediator of lipotoxicity

Cellular exposure to free fatty acids (FFA) is implicated in the pathogenesis of obesity-associated diseases. However, studies to date have assumed that a few select FFAs are representative of broad structural categories, and there are no scalable approaches to comprehensively assess the biological processes induced by exposure to diverse FFAs circulating in human plasma. Furthermore, assessing how these FFA- mediated processes interact with genetic risk for disease remains elusive. Here we report the design and implementation of FALCON (Fatty Acid Library for Comprehensive ONtologies) as an unbiased, scalable and multimodal interrogation of 61 structurally diverse FFAs. We identified a subset of lipotoxic monounsaturated fatty acids (MUFAs) with a distinct lipidomic profile associated with decreased membrane fluidity. Furthermore, we developed a new approach to prioritize genes that reflect the combined effects of exposure to harmful FFAs and genetic risk for type 2 diabetes (T2D). Importantly, we found that c-MAF inducing protein (CMIP) protects cells from exposure to FFAs by modulating Akt signaling and we validated the role of CMIP in human pancreatic beta cells. In sum, FALCON empowers the study of fundamental FFA biology and offers an integrative approach to identify much needed targets for diverse diseases associated with disordered FFA metabolism.

Highlights

FALCON (Fatty Acid Library for Comprehensive ONtologies) enables multimodal profiling of 61 free fatty acids (FFAs) to reveal 5 FFA clusters with distinct biological effectsFALCON is applicable to many and diverse cell typesA subset of monounsaturated FAs (MUFAs) equally or more toxic than canonical lipotoxic saturated FAs (SFAs) leads to decreased membrane fluidityNew approach prioritizes genes that represent the combined effects of environmental (FFA) exposure and genetic risk for diseaseC-Maf inducing protein (CMIP) is identified as a suppressor of FFA-induced lipotoxicity via Akt-mediated signaling.

Epidermal 1-O-acylceramides appear with the establishment of the water permeability barrier in mice and are produced by maturating keratinocytes

1-O-Acylceramides (1-OACs) have a fatty acid esterified to the 1-hydroxyl of the sphingosine head group of the ceramide, and recently we identified these lipids as natural components of human and mouse epidermis. Here we show epidermal 1-OACs arise shortly before birth during the establishment of the water permeability barrier in mice. Fractionation of human epidermis indicates 1-OACs concentrate in the stratum corneum. During in vitro maturation into reconstructed human epidermis, human keratinocytes dramatically increase 1-OAC levels indicating they are one source of epidermal 1-OACs. In search of potential enzymes responsible for 1-OAC synthesis in vivo, we analyzed mutant mice with deficiencies of ceramide synthases (Cers2, Cers3, or Cers4), diacylglycerol acyltransferases (Dgat1 or Dgat2), elongase of very long fatty acids 3 (Elovl3), lecithin cholesterol acyltransferase (Lcat), stearoyl-CoA desaturase 1 (Scd1), or acidic ceramidase (Asah1). Overall levels of 1-OACs did not decrease in any mouse model. In Cers3 and Dgat2-deficient epidermis they even increased in correlation with deficient skin barrier function. Dagt2 deficiency reshapes 1-OAC synthesis with an increase in 1-OACs with N-linked non-hydroxylated fatty acids and a 60% decrease compared to control in levels of 1-OACs with N-linked hydroxylated palmitate. As none of the single enzyme deficiencies we examined resulted in a lack of 1-OACs, we conclude that either there is functional redundancy in forming 1-OAC and more than one enzyme is involved, and/or an unknown acyltransferase of the epidermis performs the final step of 1-OAC synthesis, the implications of which are discussed.

The Lipid Droplet Knowledge Portal: A resource for systematic analyses of lipid droplet biology

Lipid droplets (LDs) are organelles of cellular lipid storage with fundamental roles in energy metabolism and cell membrane homeostasis. There has been an explosion of research into the biology of LDs, in part due to their relevance in diseases of lipid storage, such as atherosclerosis, obesity, type 2 diabetes, and hepatic steatosis. Consequently, there is an increasing need for a resource that combines datasets from systematic analyses of LD biology. Here, we integrate high-confidence, systematically generated human, mouse, and fly data from studies on LDs in the framework of an online platform named the "Lipid Droplet Knowledge Portal" (https://lipiddroplet.org/). This scalable and interactive portal includes comprehensive datasets, across a variety of cell types, for LD biology, including transcriptional profiles of induced lipid storage, organellar proteomics, genome-wide screen phenotypes, and ties to human genetics. This resource is a powerful platform that can be utilized to identify determinants of lipid storage.

Endogenous levels of 1-O-acylceramides increase upon acidic ceramidase deficiency and decrease due to loss of Dgat1 in a tissue-dependent manner

Except for epidermis and liver, little is known about endogenous expression of 1-O-acylceramides (1-OACs) in mammalian tissue. Therefore, we screened several organs (brain, lung, liver, spleen, lymph nodes, heart, kidney, thymus, small intestine, and colon) from mice for the presence of 1-OACs by LC-MS². In most organs, low levels of about 0.25-1.3 pmol 1-OACs/mg wet weight were recorded. Higher levels were detected in liver, small and large intestines, with about 4-13 pmol 1-OACs/mg wet weight. 1-OACs were esterified mainly with palmitic, stearic, or oleic acids. Esterification with saturated very long-chain fatty acids, as in epidermis, was not observed. Western-type diet induced 3-fold increased 1-OAC levels in mice livers while ceramides were unaltered. In a mouse model of Farber disease with a decrease of acid ceramidase activity, we observed a strong, up to 50-fold increase of 1-OACs in lung, thymus, and spleen. In contrast, 1-OAC levels were reduced 0.54-fold in liver. Only in lung 1-OAC levels correlated to changes in ceramide levels - indicating tissue-specific mechanisms of regulation. Glucosylceramide synthase deficiency in liver did not cause changes in 1-OAC or ceramide levels, whereas increased ceramide levels in glucosylceramide synthase-deficient small intestine caused an increase in 1-OAC levels. Deficiency of Dgat1 in mice resulted in a reduction of 1-OACs to 30% in colon, but not in small intestine and liver, going along with constant free ceramides levels. From these data, we conclude that Dgat1 as well as lysosomal lipid metabolism contribute in vivo to homeostatic 1-OAC levels in an organ-specific manner.

Partitioning of MLX-Family Transcription Factors to Lipid Droplets Regulates Metabolic Gene Expression

Lipid droplets (LDs) store lipids for energy and are central to cellular lipid homeostasis. The mechanisms coordinating lipid storage in LDs with cellular metabolism are unclear but relevant to obesity-related diseases. Here we utilized genome-wide screening to identify genes that modulate lipid storage in macrophages, a cell type involved in metabolic diseases. Among ∼550 identified screen hits is MLX, a basic helix-loop-helix leucine-zipper transcription factor that regulates metabolic processes. We show that MLX and glucose-sensing family members MLXIP/MondoA and MLXIPL/ChREBP bind LDs via C-terminal amphipathic helices. When LDs accumulate in cells, these transcription factors bind to LDs, reducing their availability for transcriptional activity and attenuating the response to glucose. Conversely, the absence of LDs results in hyperactivation of MLX target genes. Our findings uncover a paradigm for a lipid storage response in which binding of MLX transcription factors to LD surfaces adjusts the expression of metabolic genes to lipid storage levels.

Hepatocyte Deletion of Triglyceride-Synthesis Enzyme Acyl CoA: Diacylglycerol Acyltransferase 2 Reduces Steatosis Without Increasing Inflammation or Fibrosis in Mice

Nonalcoholic fatty liver disease (NAFLD) is characterized by excess lipid accumulation in hepatocytes and represents a huge public health problem owing to its propensity to progress to nonalcoholic steatohepatitis, fibrosis, and liver failure. The lipids stored in hepatic steatosis (HS) are primarily triglycerides (TGs) synthesized by two acyl-CoA:diacylglycerol acyltransferase (DGAT) enzymes. Either DGAT1 or DGAT2 catalyzes this reaction, and these enzymes have been suggested to differentially utilize exogenous or endogenously synthesized fatty acids, respectively. DGAT2 has been linked to storage of fatty acids from de novo lipogenesis, a process increased in NAFLD. However, whether DGAT2 is more responsible for lipid accumulation in NAFLD and progression to fibrosis is currently unknown. Also, it is unresolved whether DGAT2 can be safely inhibited as a therapy for NAFLD. Here, we induced NAFLD-like disease in mice by feeding a diet rich in fructose, saturated fat, and cholesterol and found that hepatocyte-specific Dgat2 deficiency reduced expression of de novo lipogenesis genes and lowered liver TGs by ~70%. Importantly, the reduction in steatosis was not accompanied by increased inflammation or fibrosis, and insulin and glucose metabolism were unchanged. Conclusion: This study suggests that hepatic DGAT2 deficiency successfully reduces diet-induced HS and supports development of DGAT2 inhibitors as a therapeutic strategy for treating NAFLD and preventing downstream consequences.

Probing the Global Cellular Responses to Lipotoxicity Caused by Saturated Fatty Acids

Excessive levels of saturated fatty acids are toxic to cells, although the basis for this lipotoxicity remains incompletely understood. Here, we analyzed the transcriptome, lipidome, and genetic interactions of human leukemia cells exposed to palmitate. Palmitate treatment increased saturated glycerolipids, accompanied by a transcriptional stress response, including upregulation of the endoplasmic reticulum (ER) stress response. A comprehensive genome-wide short hairpin RNA (shRNA) screen identified >350 genes modulating lipotoxicity. Among previously unknown genetic modifiers of lipotoxicity, depletion of RNF213, a putative ubiquitin ligase mutated in Moyamoya vascular disease, protected cells from lipotoxicity. On a broader level, integration of our comprehensive datasets revealed that changes in di-saturated glycerolipids, but not other lipid classes, are central to lipotoxicity in this model. Consistent with this, inhibition of ER-localized glycerol-3-phosphate acyltransferase activity protected from all aspects of lipotoxicity. Identification of genes modulating the response to saturated fatty acids may reveal novel therapeutic strategies for treating metabolic diseases linked to lipotoxicity.

Reconstructive surgery in children after meningococcal purpura fulminans

BACKGROUND/PURPOSE

Purpura fulminans (PF) is a serious, often life-threatening disease. As more children are surviving their disease, surgeons are presented with increasing numbers of multiple and complicated wounds as sequelae of PF. The purpose of this paper is to review the management of nine cases of PF, and present the reconstruction method in treating bilateral exposed elbow and knee joints.

METHODS

All cases of pediatric patients with PF and treated by the division of plastic and reconstructive surgery between 1986 and 1998 were reviewed.

RESULTS

Seven children (78%) had meningococcal PF, and one (11%) had PF after Haemophilus influenza septicemia. PF developed in one (11%) but with no growth in either blood or cerebrospinal fluid cultures. Five children (56%) required amputation procedures. Two children (22%) required knee disarticulation. Two patients (22%) had free myocutaneous flap transfers for bone coverage. One (11%) had PF involving the face.

CONCLUSIONS

Meningococcal PF is a rare, often life-threatening disease generally of childhood. More children are surviving their diseases but with devastating sequelae. Successful reconstructive treatment outcome of these children requires a multidisciplinary team approach involving multiple specialties. The goal is to preserve function, maintain maximal length, and salvage limbs when possible. Flexibility and innovation are necessary in treating these multiple and complicated wounds.

Risk factors for conduct disorder among Navajo Indian men and women

OBJECTIVES

To describe the risk factors for conduct disorder before age 15 among Navajo Indians.

METHODS

The study was based on a survey of a stratified random sample of adult Navajo Indians between the ages of 21 and 65 living on and adjacent to two different areas of the Navajo Reservation. There were 531 male and 203 female respondents. The average age (SD) of the men was 38.7 (10.5) years and of the women 35.5 (9.0) years. Conduct disorder was diagnosed retrospectively using the Diagnostic Interview Schedule first developed for the Epidemiological Catchment Area study. The responses were combined into a continuous scale.

RESULTS

Significant risk factors for increased scores on the conduct disorder scale were: histories of physical and sexual abuse in childhood; abusive maternal drinking; a small number of households per camp; younger age; and being male rather than female. Measures of social status and religion in which subjects were raised were not significant.

CONCLUSIONS

Many of the risk factors that are associated with conduct disorder in other populations are also risk factors in the Navajo population. There is suggestive evidence that some of these risk factors have become more common since World War II, raising the possibility that conduct disorder has become more prevalent, as is thought to be the case nationwide.

Alcohol dependence and conduct disorder among Navajo Indians

OBJECTIVE

The purpose of this study is to examine the association between conduct disorder before age 15 and subsequent alcohol dependence, and to describe the lifetime prevalence of alcohol dependence among Navajo Indian women and men.

METHOD

This was a case-control design which included both men (n = 735) and women (n = 351) and in which the Diagnostic Interview Schedule was used for the diagnosis of the lifetime history of alcohol dependence and conduct disorder. Alcohol dependent cases were selected from inpatient and outpatient treatment programs (204 men, 148 women). Whenever possible, controls were matched for age, sex and community of residence and were randomly selected and interviewed until a nonalcohol dependent individual was found. Among the men, there were 374 alcohol dependent controls and 157 nonalcohol dependent controls. Among the women, the figures were 60 and 143, respectively. When combined, the controls comprise samples of the adult male and female populations from which estimates of lifetime prevalence of alcohol dependence, and of the amount of alcohol dependence in the population attributable to conduct disorder, may be inferred.

RESULTS

Conduct disorder is a risk factor for alcohol dependence among both men and women. Lifetime prevalence of alcohol dependence in this population is high (70.4% for men and 29.6% for women), but the amount of alcohol dependence in the population attributable to conduct disorder is low. On the other hand, among the alcohol dependent, those with conduct disorder had the most severe alcohol- and nonalcohol-related problems.

CONCLUSIONS

The potential limitations of the study are those common to case-control designs, especially biased recall by cases. There are also potential sampling biases among the controls. It is shown that none of the potential biases invalidate the findings, which support the hypothesis that in this population conduct disorder is a risk for alcohol dependence. The implications for primary prevention of alcohol dependence are discussed.

Boarding and public schools: Navajo educational attainment, conduct disorder, and alcohol dependency

Many critics of United States government operated boarding schools for American Indians have asserted that the boarding school experience has lasting deleterious effects on personality development. Specifically, it has been suggested that a boarding school education is likely to lead to problems with alcohol in adulthood. To examine that assertion, data from interviews with over 1000 Navajos are analyzed concerning schooling, conduct disorder and the history of alcohol use. Consistent with data on the U.S. population generally, Navajo high school dropouts reported greater problems with alcohol than did graduates. Contrary to expectations, Navajos with a history of alcohol dependency were no more likely to have attended boarding schools than those who did not report patterns of alcohol dependency.

Alcohol dependence and domestic violence as sequelae of abuse and conduct disorder in childhood

OBJECTIVES

To examine in the Navajo population: (1) the importance of childhood abuse as a risk factor for conduct disorder; (2) the importance of each form of abuse and conduct disorder as risk factors for alcohol dependence; and (3) the relative importance of each form of abuse, conduct disorder, and alcohol dependence as risk factors for being a perpetrator and/or victim of domestic violence.

METHOD

The study is based on a case-control design. Cases (204 men and 148 women) between the ages of 21 and 65 were interviewed in alcohol treatment program and matched to community controls. There were two groups of controls: alcohol dependent (374 men, 60 women) and nonalcohol dependent (157 men, 143 women). When adjusted for stratification by age, community of residence, and sex, the combined control groups comprise a representative sample of the Navajo male and female population 21-65 years of age.

RESULTS

The prevalence of physical and sexual abuse before age 15 is within limits observed in other populations. Each form of abuse is a risk factor for conduct disorder. Along with conduct disorder, physical abuse is a risk factor for alcohol dependence. Physical abuse and alcohol dependence are independent risk factors for being involved in domestic violence as both perpetrator and victim. There appears to have been no secular trend in the incidence of childhood abuse over the past several generations, but there is suggestive evidence that domestic violence has become more common.

CONCLUSIONS

Physical abuse is a significant risk factor for alcohol dependence as well as for domestic violence independent of the effects of alcohol abuse. The effects of sexual abuse with regard to both domestic violence and alcohol dependence do not appear to be significant.

Minimally invasive anterior spinal exposure and release in children with scoliosis

BACKGROUND

The early experience with thoracoscopy in children has involved the diagnosis and treatment of pleural and pulmonary diseases. Recent advances have allowed surgeons to perform more complex procedures through video-assisted thoracoscopic surgery (VATS), potentially decreasing the pain and pulmonary impairment associated with an open thoracotomy. The authors report their initial experience with thoracoscopic assisted anterior spinal exposure and release as part of the treatment for children with spinal deformities.

METHODS

A retrospective chart review of five children who underwent VATS for anterior spinal surgery between June 1995 and January 1997 was performed.

RESULTS

The ages of the patients ranged from 11 to 16 years with a mean of 13.4 years. All patients had an anterior spinal release with or without fusion and same-day posterior spinal fusion with instrumentation. VATS was successfully completed in all patients without major morbidity and no mortality. The average operative time for the anterior portion of the procedure was 305 minutes, and a mean of 7 disc levels were released. Mean length of chest tube drainage and hospitalization were 6.8 and 8.6 days, respectively.

CONCLUSIONS

The objectives of anterior exposure for spinal surgery in children can safely and effectively be accomplished using minimally invasive surgery.

Neurofibromatosis

Recent advances in molecular genetics and biochemistry have defined the chromosomal abnormalities present in neurofibromatosis type 1 and type 2. The protein deficiency responsible for each syndrome has been identified. Unfortunately, this rapid progress in basic science has not yet produced an effective treatment for the underlying pathology. Patients and physicians must still deal with the various clinical manifestations and complications of neurofibromatosis; the orthopedic aspects are well known. Modern imaging does permit more effective evaluation of the patient and the particular problem so that treatments can be optimized and complications minimized.

Femoral lengthening in patients having abnormal ipsilateral hip or knee

Femoral lengthening using the Wagner technique was performed for 13 patients with abnormal adjacent joints. An average of 6.3 cm (19.5%) of lengthening was achieved. Three patients had no difficulties during lengthening. Transient non-surgical problems identified were blood pressure elevation, nerve palsy, and psychiatric reactions. Significant obstructions or complications occurred 13 times in nine cases. These included contractures of ipsilateral joints, angulations of the lengthened femur, Wagner device slippage, nonunion, and late hip subluxation. Other authors have reported similar difficulties in patients with normal ipsilateral joints. In this series, the advantage of achieving greater length appeared to outweigh the complications.

Percutaneous epiphyseodesis

The records of 29 patients who underwent epiphyseodesis of 56 physes in which a percutaneous (minimal incision) technique was used were reviewed. Length of surgery averaged 36 min per physis. Growth arrest was achieved in every instance. There were no cases of unplanned angular growth, no deep infections, and no difficulties in regaining full joint motion were reported. Epiphyseodesis of the proximal tibial physis was performed on 16 patients without epiphyseodesis of the proximal fibula, yet symptoms attributable to fibular overgrowth were not reported. Some technical variations that have evolved in our procedure are described.

Comparison of native prothrombin antigen with the prothrombin time for monitoring oral anticoagulant prophylaxis

BACKGROUND

Oral anticoagulation is most frequently monitored using the prothrombin time, but an alternative approach is measurement of native, fully carboxylated, prothrombin antigen (NPA). We have correlated results of the prothrombin time and NPA with development of venous thrombosis or bleeding complications in a clinical trial of warfarin prophylaxis following total hip arthroplasty to determine the potential value of NPA measurement for monitoring oral anticoagulation.

METHODS AND RESULTS

Patients in one arm of a prospective, randomized trial received warfarin prophylactically beginning 10 to 14 days before total hip arthroplasty in a dose adjusted to prolong the international normalized ratio (INR) to 1.5 on the day of surgery and 2.5 after surgery. NPA was measured by ELISA, and the prothrombin time was measured using rabbit brain thromboplastin. Samples were tested from 97 patients, and data from 81 patients who had adequate venography were analyzed to correlate test results with occurrence of thrombosis. The prothrombin time and INR were less sensitive than NPA to the lowest intensities of anticoagulation, with the prothrombin time index increasing from 1.0 to 1.3 and the INR increasing from 1.0 to 2.0, whereas the NPA concentration decreased fourfold, from 200 to 50 micrograms/mL. There was little correlation between either the prothrombin time index or the INR and the development of thrombosis, whereas NPA concentrations were significantly higher on the day of surgery and on postoperative days 1, 3, 5, and 7 in patients who developed venous thrombosis. Higher concentrations of NPA were associated with an increased risk of venous thrombosis, but there was no relation between thrombosis and the prothrombin time index or INR. There was no significant correlation between surgical blood loss and prothrombin time index, INR, or NPA concentration. However, patients who received the largest number of transfusions on the day of surgery had significantly lower NPA concentrations than patients who required no transfusion.

CONCLUSIONS

These results indicate that the NPA concentration more accurately reflects the antithrombotic effect of warfarin than does prothrombin time and may be superior in monitoring prophylactic oral anticoagulation.

Clinicopathologic correlates in Alzheimer disease: assessment of clinical and pathologic diagnostic criteria

The neuropathologic findings from a group of 123 patients who have come to autopsy from the Rochester Alzheimer Disease Project (RADP) are presented. Among these 123 cases, there were 94 demented subjects who met the National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer Disease and Related Disorders Association (NINCDS-ADRDA) clinical criteria for the diagnosis of "probable Alzheimer disease," and 29 normal elderly controls. Autopsy confirmation of Alzheimer disease (AD) was based on the age-graded National Institutes of Health (NIH) consensus conference pathologic criteria. Using the NINCDS-ADRDA clinical criteria and the NIH pathologic criteria, the diagnostic accuracy was 88%, the sensitivity was 98%, and the specificity was 69%. Additional strict clinical and pathologic criteria developed by the RADP were applied in the final review of these cases to exclude all confounding causes of dementia, including cerebral infarcts. After applying these additional criteria, a subset of 62 cases of "pure" AD and "pure" control subjects was identified for a more detailed examination of neuritic plaques (NP) and neurons containing neurofibrillary tangles (NFT). The NP and NFT were counted in three subfields of hippocampus and two areas of association neocortex. The density of diffuse plaques (plaques lacking dystrophic neurites) was estimated on a semiquantitative basis. Results show that the AD patients and control groups could be distinguished from each other easily on the basis of mean NP and NFT counts, but there was sufficient overlap in the counts to present difficulty in diagnosing any individual case. Abundant diffuse plaque involvement and NFT in the neocortex were, however, seen only in AD cases.

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.

Second operation for slipped capital femoral epiphysis: pin removal

Pin removal procedures were retrospectively reviewed for 43 hips in 31 patients. Original treatment had included use of Knowles, Steinmann, Hagie, and cannulated steel pins. Time to pin extraction ranged from 5 to 70 months. Average operative time was slightly more than 1 h and average blood loss was 127 ml. Bone overgrowth and difficult extraction was encountered with all pin types. Pin breakage during extraction was recorded with Steinmann and Knowles pins. Delay in return to full activity postoperatively was a common complaint. This study shows that pin removal is not without certain costs and risks.

Comparison of warfarin and external pneumatic compression in prevention of venous thrombosis after total hip replacement

OBJECTIVE

To compare the effectiveness and safety of warfarin and external pneumatic compression (EPC) in prevention of venous thrombosis after total hip replacement.

DESIGN

Prospective, randomized trial in consecutive patients, with blinded assessment of the primary end point.

SETTING

University medical center and large community hospital.

PATIENTS

Patients over age 18 years scheduled for elective primary total hip replacement were eligible. Of 254 patients interviewed, 232 were randomized, 220 patients had surgery and received prophylaxis, and 201 had venography.

INTERVENTIONS

Patients were randomly assigned to prophylaxis with a device providing bilateral sequential EPC to both the calf and thigh or to receive warfarin in a low-intensity regimen beginning 10 to 14 days preoperatively. Prophylaxis was continued until venography.

MAIN OUTCOME MEASURES

Venous thrombosis was diagnosed by venography between postoperative days 6 and 8. Bleeding was assessed by surgical blood loss, transfusion requirements, changes in hematocrit, and clinically identified bleeding complications.

RESULTS

The total incidence of venous thrombosis was virtually the same in the warfarin and EPC groups (31% vs 27%), but the distribution of thrombi was different. Proximal thrombosis occurred in 12% of patients in the EPC group compared with only 3% in the warfarin group (P = .012, 95% confidence interval for difference, 2% to 18%). In contrast, calf vein thrombosis was more frequent in the warfarin group (21%) than in the EPC group (12%) (P = .021, 95% confidence interval for difference, 0% to 18%). Most proximal thrombi in EPC-treated patients were located within 15 cm of the femoral head and were not continuous with thrombi in deep calf veins. The high incidence of proximal thrombosis in the EPC group resulted in termination of the study by the safety monitoring committee. Blood loss and bleeding complications were similar in the two groups.

CONCLUSION

Warfarin therapy is significantly more effective than EPC in preventing serious proximal vein thrombosis after total hip replacement. The greater effectiveness of warfarin therapy in preventing proximal vein thrombi and of EPC in preventing thrombosis in the calf suggests that there are differences in the pathogenesis of thrombosis in these two locations.

Longitudinal radiologic evaluation of osteoarthritis of the knee

Radiologic assessment appears to be an objective standard for longterm evaluation of osteoarthritis (OA) and it is inexpensive, quick, simple and noninvasive. We conducted a one year followup study of patients with OA of the knee to evaluate the reproducibility and validity of this evaluation. The intra and interobserver reproducibility of the radiologic variables were evaluated on 275 and 539 patients, respectively, and found to be satisfactory (intraclass coefficient of correlation above 0.70 for the evaluation of the space narrowing of the joint). During the one year followup study, there was a slight but statistically significant deterioration of the joint space narrowing, evaluated on a 6 grade scale on 360 patients (p less than 0.001). The changes in the joint space narrowing were more closely correlated with treatments received by the patients for OA (nonsteroidal antiinflammatory drug (NSAID) intake, synovial fluid aspiration) than with changes in the recorded clinical variables (pain on a visual analog scale, Lequesne algofunctional index). Moreover, some factors such as obesity, generalized OA and flares of OA appeared to be correlated with the deterioration of joint space narrowing. Further studies are necessary to confirm and/or explain the relationship between the deterioration of the joint space narrowing and such factors (i.e., NSAID intake, obesity, flares of OA, generalized OA), which were detected in this study.

Occipito-atlantal translation in Down's syndrome

Several cases of occipito-atlantal instability have been reported in patients with Down's syndrome. However, standards for radiographic measurement and normal values for translational motion at the occiput-C1 level have not been established for the Down's patient. A retrospective analysis of 102 flexion and extension lateral cervical spine radiographs of 73 patients with Down's syndrome was performed. Patients with congenital cervical spine anomalies, C1-C2 instability, or previous neck surgery were excluded. Occiput-C1 translation was measured by the technique described by Wiesel and Rothman. In normal adult patients, occiput-C1 translation should be no more than 1 mm by this method. Analysis of the data demonstrated a range of 0 to 10 mm, with a mean of 2.62 mm and a standard deviation of +/- 1.94 mm. Only 30 sets of films (29%) representing 27 patients (37%) showed anteroposterior translation of 1 mm or less. This laxity was not dependent on patient age in the current study group. A review of these patients' medical records did not disclose any evidence of impaired neurologic function related to cervical spine instability. The authors' data suggest that the prevalence and magnitude of occipito-atlantal instability in Down's syndrome is greater than previously appreciated.

Quantitation of venous clot lysis with the D-dimer immunoassay during fibrinolytic therapy requires correction for soluble fibrin degradation

Plasma cross-linked fibrin-degradation products were analyzed using a D-dimer (DD) immunoassay in patients with deep vein thrombosis (DVT) or acute myocardial infarction (MI) treated with fibrinolytic therapy, and the results were correlated with clot lysis documented angiographically. In 13 patients with DVT, the mean DD concentration increased 10-fold (1,074 +/- 252 to 10,333 +/- 1,004 ng/ml) during therapy, but neither the peak level nor the DD concentration integrated over the course of therapy correlated with clot lysis. Since plasma DD can derive from degradation of soluble plasma fibrin as well as from thrombi, the contribution of the former was estimated by in vitro incubation of the pretreatment plasma with plasminogen activator. Subtraction of this value from the measured posttreatment DD concentration provided a "corrected" level that represented DD originating from lysis of thrombi. This modification resulted in improved correlation of DD levels with clot lysis. The mean corrected peak DD was higher in patients with successful thrombolysis (8,780 +/- 1,352 ng/ml) compared with patients without lysis (3,075 +/- 589 ng/ml, p less than 0.001). There was a moderate correlation between the volume of clot lysed and the corrected peak DD (r = 0.62) and a higher correlation with the corrected DD integrated over the course of treatment (r = 0.97). By contrast, the corrected DD concentrations were near zero in patients treated for MI with or without thrombolytic reperfusion, suggesting that fibrin in small coronary thrombi did not contribute significantly to total plasma DD during therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Biplots in biomedical research

The biplot is a graphical display of multivariate data. A number of examples from biomedical research illustrate its use. Biplots allow for inspection of data preliminary to formal analysis, and can follow an analysis by the graphical inspection of residuals. The simplicity and intuitive appeal of these displays is stressed. An appendix indicates their method of construction and the software for producing them.

Prevention of venous thrombosis after total hip arthroplasty. Antithrombin III and low-dose heparin compared with dextran 40

The anticoagulant action of heparin is mediated through antithrombin III, and the postoperative decrease in the plasma concentration of antithrombin III may contribute to the relative ineffectiveness of prophylaxis with low-dose heparin in preventing venous thrombosis after total hip arthroplasty. We conducted a prospective, randomized trial to compare the effectiveness of a regimen of antithrombin III, given intravenously once daily, and low-dose heparin with a regimen of dextran 40, given intravenously, in preventing venographically documented venous thrombosis after total hip arthroplasty. The results demonstrated an incidence of venous thrombosis of 4.9 per cent in patients who received antithrombin III and heparin; this was significantly lower than the incidence (28.6 per cent) in patients who received dextran 40 (p less than 0.005). Venous thrombosis occurred only in patients who had total hip arthroplasty with a cemented prosthesis (fourteen of fifty-seven patients, or 24.6 per cent); none of the twenty-six patients in whom a non-cemented prosthesis was used had venous thrombosis (p less than 0.01). Of the patients in whom a cemented prosthesis had been inserted, the incidence of venous thrombosis was lower in those who were treated with antithrombin III and heparin (7.4 per cent) than in those who were treated with dextran 40 (40 per cent) (p less than 0.005). Postoperative levels of antithrombin III were maintained at more than 90 per cent of the baseline level in patients who received it; this was significantly higher than in patients who received dextran 40.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification of acute posttraumatic spinal cord cyst by magnetic resonance imaging: a case report and review of the literature

Posttraumatic spinal cord cysts have traditionally been diagnosed late. The condition is usually considered after the neurological sequelae of spinal cord trauma have not resolved. The diagnosis has usually required invasive radiographic techniques, or even surgical exploration. Magnetic resonance imaging is a new, non-invasive diagnostic technique that appears to be more accurate than previous procedures. Moreover, it has the ability to delineate spinal cord parenchymal lesions much earlier than other methods. We present a case report and literature review of posttraumatic spinal cord cyst.

Foot and ankle problems

The most common reason for children presenting to the general or the pediatric orthopedist has to do with foot problems. The usual age group ranges from the neonate to preschool. The authors have made an attempt to present guidelines for our approach to foot problems other than clubfoot in these age groups and have rendered our recommendations for treatment. We feel that pediatric and general orthopedists will be able to utilize our methods in the management of the pediatric patient with the more commonly presenting foot disorders.

Cultural values and biomedical knowledge: choices in infant feeding. Analysis of a survey

This paper presents a study of 313 parturient women and considers their choices to bottle or breast feed. It examines demographic and cultural factors statistically and focuses on the effect of knowledge or ignorance of benefits of either method of infant feeding. Most women are found to have some biomedical knowledge of the benefits of breast feeding. The choice of bottle or breast feeding is closely associated with several demographic factors and a number of cultural ideas. Women who bottle feed see some of their dietary and other health related practices as barriers to breast feeding. It recommends that health practitioners who decide that individual women and/or their infants may benefit from breast feeding, should engage in a dialogue with the women. Such a dialogue should focus, not so much on information, but on the woman's views about her dietary and other health practices. If the woman is given compelling health reasons she may see herself as capable of changing some practices long enough to breast feed.

Do psychiatric patients fit their diagnoses? Patterns of symptomatology as described with the biplot

Systems of psychiatric diagnosis have been regularly criticized for their low reliability and their inability to fit accurately the kinds of patients coming for treatment. To explore the reasons for these problems, this study utilizes a new method, the biplot, for defining groups of similar patients and the relationships of these groups to key symptom clusters. Using this technique to analyze data from a representative sample of first admissions for psychiatric disorder, results showed: a) symptom clusters representing the classical diagnostic categories, mania, schizophrenia, neurotic depression, and psychotic depression, were readily identified; b) however, only a few patients were clustered near these traditional syndromes. These findings suggest that although syndromes do exist that fit traditional diagnostic categories, the vast majority of patients fall between these syndromes, having characteristics from several of them. For most patients, forcing the diagnostician to choose among the categories requires an arbitrary decision that may contribute to dissatisfaction in the diagnostician who recognizes how misleading the diagnosis can be.