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Biomedical subjects

K Cox

Publications and source records attributed to K Cox.

At least 127 records · Page 7Linked to original sources
PubMed1991

The impact of liver reductions in pediatric liver transplantation.

Reduced-size liver transplantation (RSLT) in children was introduced to alleviate a shortage of small-organ donors. The impact of RSLT on the waiting time for an organ and on morbidity and mortality was investigated. Between March 25, 1988, and August 11, 1990, 61 hepatic transplantations were performed in 55 children at the Pacific Transplant Institute in San Francisco, Calif. Full-size liver transplantation was performed in 41 cases and RSLT in 20 cases. The overall 30-month actuarial patient and graft survival rates were 89% and 73%, respectively. A comparison between full-size liver transplantation and RSLT showed no difference in patient and graft survival, reoperations, infections, or rejection. Benefits of RSLT were an increase in the donor pool size, a decrease in waiting time for a suitable donor, and a decrease in the rate of arterial thrombosis. The main morbidity of RSLT was an increase in perioperative blood requirement. We conclude that RSLT offers small children with end-stage liver disease a chance for long-term survival.

Actuarial Analysis↗
PubMed1991

Parvalbumin-immunoreactive neurons in the neocortex are resistant to degeneration in Alzheimer's disease.

Recent studies have stressed the fact that specific neuronal subtypes may display a differential sensitivity to degeneration in Alzheimer's disease. For example, large pyramidal neurons have been shown to be vulnerable, whereas smaller neurons are resistant to pathology. Using a monoclonal antibody against the calcium-binding protein parvalbumin, we investigated the possible changes in a subpopulation of interneurons in two cortical areas known to be strongly damaged in Alzheimer's disease. In the prefrontal cortex as well as in the inferior temporal cortex, we observed no differences in parvalbumin-immunoreactive cell counts or cell size in Alzheimer's disease brains as compared to control cases. Moreover, the general cellular morphology of these neurons was preserved in the Alzheimer's disease cases, in that their perikarya and dendritic arborizations were intact. These results suggest that paravalbumin-immunoreactive cells represent a neuronal subset resistant to degeneration, and further support the hypothesis that the pathological process in Alzheimer's disease involves specific neuronal subtypes with particular morphological and molecular characteristics.

Aged↗
PubMed1991

Unilateral external fixation until healing with the dynamic axial fixator for severe open tibial fractures.

One hundred one cases of open tibia fractures were treated until healing with a unilateral external fixation device that permits fracture site compression with weight bearing. There were 38 type II and 63 type III (24 IIIA, 33 IIIB, six IIIC) open fractures. A standard protocol was followed including irrigation and debridement and, when necessary, flap coverage (19 cases) and bone grafting (31 cases). Fixators were applied at the first debridement and removed when the fracture was healed. All patients were permitted early partial weight bearing and progressed to full weight bearing with fixator dynamization. Ninety-six cases healed in the fixator (12-50 weeks; average, 24.6). Three of the five failures were associated with screw complications. Five patients required screw changes and 29 required oral antibiotic therapy for screw complications. Ninety-five percent of healed cases had angulation of less than 10 degrees (in any plane). There were only six fracture site infections during the course of treatment. Dynamic axial fixation may be applied at the first debridement and be used until healing in severe open tibia fractures. Change of the fixator to another treatment method is not required.

Adolescent↗
PubMed1991

Sleep medication in Dutch hospitals.

Insomnia is an important nursing problem in hospitals. Although sleep medication is often criticized, it is one of the commonest interventions with regard to sleep problems. In this study, the prescription and provision of sleep medication in three Dutch general hospitals is investigated. Results show that on a random day 47% of all patients (n = 1076) of the surgical and medical wards were prescribed medication. Thirty-four per cent actually received sleep medication that evening or night. The prescription and provision of sleep medication was higher on medical than on surgical wards. Furthermore, hospitals were shown to differ regarding the prescription and provision of as-needed sleep medication. The study also explores whether attitudes of nurses are related to the provision of as-needed sleep medication. Although their influence does not seem to be great, it is concluded that more attention has to be paid to possible effective nursing interventions in educational programmes.

Adult↗
PubMed1991

The sensitivity of antibody detection testing using pooled versus unpooled reagent red cells.

Evaluation of paternity (alleged father, mother, and child) can range from a straightforward resolution to a complex problem that cannot be resolved without family studies. We present a case of disputed paternity in which tests for crossreactive groups (CREcS) and antigen subtypes (splits) within the human leukocyte antigen (HLA) system could not be used confidently to prove or disprove paternity. Further analysis, red cell enzyme tests, enabled a final verdict and confirmed the current reliability of HLA antisera defining splits.

Journal Article↗
PubMed1991

Liver transplantation. Experience with 100 cases.

Between March 1988 and November 1989, 100 liver transplants were performed on 90 patients at Pacific Presbyterian (now California Pacific) Medical Center in San Francisco. The immunosuppressive regimen was a combination of prophylactic Minnesota antilymphocyte globulin, cyclosporine, and low-dose corticosteroids. Rejections were treated with OKT3, a monoclonal antibody, or corticosteroids. Of the 100 transplants, 32 were done on 30 children, 18 of whom weighed less than 10 kg and 9 of whom received livers that had been surgically reduced in size to fit the recipient. The overall patient survival at 2 years was 85%. Of 100 liver transplants, treatment was given for 80 (80%) for at least 1 episode of rejection. At least 1 episode of serious infection occurred in 34 of the 60 adult patients and 25 of the 30 children. Of the entire group, 2% had hepatic artery thrombosis, and 12% had biliary complications that necessitated reoperation. The quality of life has been good, with a follow-up from 1 to almost 3 years (mean = 22 months). Comparing these data with those of other published series shows a decreased incidence of surgical complications and a lower rate of fungal and viral infections. We attribute this to the reduction of steroid dosage during convalescence without jeopardizing patient or graft survival.

Adolescent↗
PubMed1991

Disciplines within general practice.

The disciplines within general practice derive partly from its community setting, and partly from the nature of professional expertise. The maladies range from a high prevalence of low risk, self-limited illness to a low prevalence of high risk, persistent disease. Each set calls on different knowledge and skills. The setting offers the substrate for studying social and behavioural sciences and community health development in action. Choosing a few particular fields, and developing those with rigour, could strengthen general practice as a discipline with special insights and skills to offer all branches of clinical practice. Four fields of activity have been identified. In each, general practice has a clear responsibility and opportunity. I have suggested some knowledge and skill areas for their success--clinical 'working' knowledge, decision making and judgment, predictive knowledge, planning knowledge, calibration of investigators, intuitive knowledge, local knowledge, leadership skills and people management, measurement of burden of illness, calculation of cost-benefit trade-offs, building of local databases, re-learning fine discrimination in clinical perception, and understanding of community development. These subjects have not been part of formal medical education, or of much academic study in family practice. Despite their being central to the success of daily practice, the curriculum is silent about the study of these areas of practical knowledge, reasoning, judgment and skill. Worse, we do not have a common language to express clearly what we are talking about. Experience and skill lie within the practitioner, and are used in practical, concrete situations.(ABSTRACT TRUNCATED AT 250 WORDS)

Family Practice↗
PubMed1990

Quantitative analysis of a vulnerable subset of pyramidal neurons in Alzheimer's disease: I. Superior frontal and inferior temporal cortex.

Various cytoskeletal proteins have been implicated in the cellular pathology of Alzheimer's disease. A monoclonal antibody (SMI32) that recognizes nonphosphorylated epitopes on the medium (168 kDa) and heavy (200 kDa) subunits of neurofilament proteins has been used to label and analyze a specific subpopulation of pyramidal neurons in the prefrontal and inferior temporal cortices of normal and Alzheimer's disease brains. In Alzheimer's disease, the distribution of neuropathological markers predominates in layers III and V in these association areas. In these neocortical regions, SMI32 primarily labels the perikarya and dendrites of large pyramidal neurons, predominantly located within layers III and V. In Alzheimer's disease, a dramatic loss of SMI32-immunoreactive (ir) cells was observed, affecting particularly the largest cells (i.e., cells with a cross-sectional perikaryal area larger than 350 microns 2). The staining intensity of the largest SMI32-ir neurons was significantly reduced in Alzheimer's disease cases, suggesting that an inappropriate phosphorylation of these cytoskeletal proteins may take place in the course of the pathological process. In addition, the SMI32-ir neuron loss and total neuron loss were highly correlated with neurofibrillary tangle counts, whereas such a correlation was not observed with neuritic plaque counts. These quantitative data suggest that SMI32-ir neurons represent a small subset of pyramidal cells that share certain anatomical and molecular characteristics and are highly vulnerable in Alzheimer's disease. Other studies have suggested that SMI32-ir neurons are likely to furnish long corticocortical projections. Thus, their loss would substantially diminish the effectiveness of the distributed processing capacity of the neocortex, resulting in a neocortical isolation syndrome as reflected by the clinical symptomatology observed in these patients. Such correlations between the expression of a selective cellular pathology and specific elements of cortical circuitry will increase our understanding of the molecular and cellular characteristics underlying a given neuronal subclass vulnerability in Alzheimer's disease or other neurodegenerative disorders.

Aged↗
PubMed1990

Selection of the T-cell repertoire in transgenic mice expressing a transplantation antigen in distinct thymus subsets.

Transgenic mice that expressed a transplantation antigen, H-2Kb, in an unusual tissue distribution have been developed. Gene-regulatory elements from the immunoglobulin heavy-chain locus (Emu enhancer and heavy chain promoter) were linked to the class I Kb gene and the construct microinjected into fertilized mouse eggs of a different haplotype. It was expected that such gene-regulatory elements would direct expression of the foreign class I molecules only to B and T lymphocytes. However, expression was also detected in a subset of thymus medullary epithelium. The Kb molecules expressed on this thymic subset were unable to positively select T cells for passage to the periphery. The mice were, however, tolerant of the cell types expressing the foreign Kb molecules and were also tolerant of Kb presented as skin grafts. These results suggest that not all components of thymic epithelium are involved in positive selection of T cells and that transplantation antigens expressed on non-dendritic cells can induce tolerance.

Animals↗
PubMed1990

Low-dose aspirin. II. Relationship of angiotensin II pressor responses, circulating eicosanoids, and pregnancy outcome.

Forty pregnant women (28 to 32 weeks' gestation) were given low-dose aspirin therapy (81 mg/day) from the time of enrollment until delivery; circulating eicosanoid levels and angiotensin II pressor responses were measured before and after 1 week of aspirin therapy. Subsequent clinical outcome was correlated with these results. All women had significant reductions in serum and plasma thromboxane B2 levels with aspirin treatment (p less than 0.01). Eleven women who remained sensitive to the pressor effects of angiotensin II (effective pressor dose less than 10 ng/kg/min) after 1 week of low-dose aspirin treatment exhibited significant decreases (p less than 0.05) in plasma 6-keto-prostaglandin F1 alpha (264 +/- 119 vs 161 +/- 31 pg/ml, mean +/- SD) and prostaglandin E2 (476 +/- 174 vs 351 +/- 112 pg/ml) levels. In contrast, patients who were either nonsensitive (refractory) to angiotensin II (n = 18; greater than or equal to 10 ng/kg/min) before aspirin or became nonsensitive after aspirin administration (n = 11) had no change in either plasma 6-keto-prostaglandin F1 alpha or prostaglandin E2 concentrations. The occurrence of pregnancy-induced hypertension was 100% in the women who remained angiotensin II sensitive during aspirin therapy as compared with 36% and 39% in the other two groups (x2 = 16.14; p less than 0.001). Thus during low-dose aspirin therapy a failure to develop refractoriness to infused angiotensin II is associated with a nonselective inhibition of eicosanoids and the almost certain development of pregnancy-induced hypertension. These observations may reflect a basic defect in vascular adaptation to pregnancy.

6-Ketoprostaglandin F1 alpha↗
PubMed1990

No Oscar for OSCA.

Structured examination methods are deservedly popular for testing component skills in medicine. Use of the methods, however, has been carried into assessment of complex performance. The note explains the inappropriateness of such use, and suggests the use of assessments based on daily clinical tasks.

Clinical Competence↗
PubMed1989

Effects of bone matrix components on osteoclast differentiation.

When implanted subcutaneously in rats, devitalized bone particles (BP) elicit the differentiation of osteoclastic cells. Those cells can be distinguished from foreign body giant cells that form in response to particulate plastics. Osteoclast features include resorption of the bone substrate, ruffled borders, calcitonin receptors, tartrate-resistant acid phosphatase activity, and modulation by bone active agents. To determine whether expression of these features depends on specific components of the matrix, we characterized the multinucleated cells that developed in response to osteocalcin-deficient BPs, particulate microcrystalline hydroxyapatite (HA), and HA containing 0.1% osteocalcin, collagen, or bovine serum albumin. Only those particles that contained mineral and osteocalcin were associated with osteoclastic cells. These studies support the hypothesis that osteocalcin may function as a matrix signal in the differentiation of osteoclasts.

Animals↗