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Biomedical subjects

G Walker

Publications and source records attributed to G Walker.

At least 91 records · Page 5Linked to original sources
PubMed1993

Freestanding ambulatory surgery: cost-containment winner?

In many states, freestanding, ambulatory surgery centers (ASCs) are being permitted to provide overnight, postoperative recovery and observation services. As a result, ASCs are now able to perform surgical procedures that were once the exclusive province of hospital-based outpatient surgery departments. As an analysis of data gathered in Florida and North Carolina illustrates, freestanding ASCs usually have lower charges than their hospital-based counterparts. This finding suggests that hospitals will have to take steps to control their ambulatory surgery costs if they want to compete successfully in the race for ambulatory surgery dollars.

Ambulatory Surgical Procedures↗
PubMed1993

'Routine' antenatal care.

The concept of antenatal care is a good model of preventive health targeted towards primary and secondary prevention of diseases and pathological conditions during pregnancy and delivery. A critical evaluation of antenatal care programs demonstrated that these are generally associated with a wide range of positive effects, although the type of care provider is not. However, research methodological limitations such as the selection bias (more care is received by healthier women who will have better outcomes anyway), cannot be ruled out as an explanation for the positive results.

Female↗
PubMed1992

Adjudicated pricing--when rates are challenged in court.

When the courts become involved in taking hospitals to task for their prices, hospital financial officers should prepare themselves for the unpleasant, potentially costly, and time-consuming legal dance that awaits them. The authors examine the pitfalls of judicial regulation of hospital charges and offer suggestions on how hospitals can avoid legal challenges or best prepare to meet them.

Cost Allocation↗
PubMed1991

Mapping the binding domain of a myosin II binding protein.

The way in which actin and myosin II become localized to the contractile ring of dividing cells resulting in cleavage furrow formation and cytokinesis is unknown. While much is known about actin binding proteins and actin localization, little is known about myosin localization. A 53-kDa (53K) polypeptide present in the sea urchin egg binds to myosin II in a nucleotide-dependent manner and mediates its solubility in vitro [Yabkowitz, R., & Burgess, D.R. (1987) J. Cell Biol. 105, 927-936]. The binding site of 53K on the myosin molecule was examined in an effort to understand the mechanism of 53K-induced myosin solubility and its potential function in myosin regulation. Blot overlay and chemical cross-linking techniques utilizing myosin proteolytic fragments indicate that 53K binds to fragments proximal to the head-rod junction of myosin. Fragments distal to the head-rod junction do not bind 53K. In addition, the binding of 53K to myosin largely inhibits protease digestion that produces the head and rod fragments. The binding of 53K to the head-rod domain of myosin may be critical in regulation of myosin conformation, localization, assembly, and ATPase activity.

Animals↗
PubMed1991

Africa's health.

Explore the source record for details and available documents.

Africa↗
PubMed1991

Localization of type X collagen in canine growth plate and adult canine articular cartilage.

Type X collagen was extracted from ends of canine growth plates by pepsin digestion after 4 M guanidine hydrochloride extraction, purified by stepwise salt precipitation (2.0 M NaCl in 0.5 M acetic acid), and chromatographed on a Bio-Gel A1.5 M column in 1.0 M CaCl2. Without reduction on sodium dodecyl sulfate (SDS) polyacrylamide gels, the preparation yielded a single, high-molecular-weight (mol wt) band; after reduction, a single band of relative mol wt 5.0 x 10(4) was found. Polyclonal sera were raised against the purified collagen and used in the immunolocalization of canine type X collagen. As expected, indirect immunoperoxidase (IP) or indirect immunofluorescent staining with the polyclonal sera demonstrated that most of the immunoreactivity was localized in the zone of provisional calcification of the growth plate and in cartilage remnants in the metaphyseal region of the physis. A progressive decrease in staining toward the diaphysis of the fetal canine long bone was apparent as the trabecular structures were remodeled to bone. Unexpectedly, type X collagen was also detected in the zone of calcified, mature articular cartilage. It was concentrated in the pericellular matrix of the chondrocytes, appeared at or just above the tidemark, and was expressed immediately before mineralization. Identification of type X collagen in both the canine growth plate and the zone of calcified articular cartilage suggests that cells in the deep layer of cartilage and in the zone of calcified cartilage in the adult animal retain some characteristics of a growth plate and may be involved in regulation of mineralization at this critical interface. The expression of growth plate-like properties would allow the deep chondrocytes of mature articular cartilage to play a role in remodeling of the joint with age and in the pathogenesis of osteoarthritis.

Animals↗
PubMed1991

Safe, stable, whole blood samples for quality assessment of glucose measurement by non-laboratory staff.

A whole blood control material has been used to assess the analytical performance of non-laboratory staff who use glucose meters in clinical areas. It is prepared from sterile horse blood which is readily available from a commercial source. There are no known infection or disease transmission risks to users. When the material is stabilized by the addition of sodium fluoride less than 3% loss of glucose over 48 h is observed from an initial value of 10 mmol/L. However, we prefer to stipulate that the glucose is measured on the day of receipt. The material has been used successfully with Reflolux IIM meters and B-M sticks (Boehringer Mannheim, UK) for over a year in our hospital.

Animals↗
PubMed1991

The morbidity of long-term seizure monitoring using subdural strip electrodes.

The authors report a prospective study of morbidity associated with long-term seizure monitoring using subdural strip electrodes. Three hundred fifty patients were divided into two groups: 175 patients received antibiotics intravenously during the entire period that the electrodes were implanted, and 175 patients received one dose of antibiotics on the morning of surgery. In the group given continuous antibiotic coverage there were two cases of meningitis, both treated without sequelae. In the group receiving one dose of antibiotics, one patient had a brain abscess and three had superficial wound infections. There were no other instances of major morbidity or mortality in either group of patients. The total morbidity rate for both serious and minor complications was 0.85%.

Adult↗
PubMed1991

Transcutaneous magnetic and electrical stimulation over the cervical spine: excitation of plexus roots-rather than spinal roots.

Percutaneous magnetic stimulation (MagStim) and electrical stimulation (ElStim) over the cervical spine were performed in 65 subjects. Compound muscle action potentials (CMAPs) from the abductor digiti minimi (ADM) and the biceps muscles (BICEPS) could be recorded in all subjects tested with both, ElStim and MagStim. Maximal stimulation as determined from the amplitudes of CMAPs was possible in most cases with ElStim but not with MagStim. Latencies after MagStim (centered over C7) and ElStim (cathode over C7/T1, anode positioned 6 cm cephalad in the midline) were not statistically significantly different (P = 0.3). However, in the individual case, it was difficult to predict the precise site at which the motor roots would be activated, since latencies of CMAPs to ElStim and MagStim could differ by up to 1.2 msec. In addition, the excitation site migrated distally when the stimulation intensity was increased with the aim to obtain CMAPs of nearly maximal amplitudes. The results of studying brachial plexus stimulation as well in 22 of the subjects led us to the conclusion that excitation of the motor roots occurs on the average 7 cm (range: 1.4-8.2 cm) proximally to Erb's point. This was confirmed by the finding that when the C7 motor root was stimulated directly intraoperatively within the intervertebral foramen, the excitation site was calculated to be 7.7 cm distal to the foramen and 8.4 cm proximal to Erb's point.

Action Potentials↗
PubMed1991

Performance of techniques used to detect drugs of abuse in urine: study based on external quality assessment.

Twenty-five samples of lyophilized urine from the U.K. External Quality Assessment Scheme for Drugs of Abuse were analyzed by an average of 95 laboratories between April 1987 and December 1989. Samples contained mixtures of analytes and included replicated concentrations of morphine, methadone, amphetamine, and cocaine at 0, 1, 2, and 5 mg/L and of benzoylecgonine at 0, 0.4, 1, 2, and 4 mg/L. Some chromatographic techniques were inadequate for detecting morphine, amphetamine, cocaine, and benzoylecgonine at the lower concentrations of analytes studied: gas-liquid chromatography was least sensitive for morphine; in-house thin-layer chromatography (TLC) was least sensitive for the other analytes. Few significant differences in specificity were detected between techniques, although significant interference from structurally related compounds was demonstrated in assays of morphine, methadone, and amphetamine. Exceptions were the Boehringer (BCL) test for opiates and TLC applied to amphetamine and benzoylecgonine, which demonstrated considerable lack of specificity.

Amphetamine↗
PubMed1990

Tumor necrosis factor alpha/cachectin stimulates eosinophil oxidant production and toxicity towards human endothelium.

Eosinophils (EOs) participate in a variety of inflammatory states characterized by endothelial cell damage, such as vasculitis, pneumonitis, and endocarditis. We find that 100 U/ml TNF-alpha/cachectin (TNF), a concentration attainable in the blood of humans with parasitic infestations, stimulates highly purified populations of EOs to damage human umbilical vein endothelial cells (HUVEC), a model of human endothelium. This TNF-dependent EO cytotoxicity is strongly inhibited by heparin and methyprednisolone but unaffected by the platelet-activating factor antagonist BN52012 or scavengers of superoxide anion and H2O2, superoxide dismutase and catalase. However, addition of a physiologically relevant concentration of Br- (100 microM) enhances EO/TNF damage to HUVEC, implicating the possible participation of EO peroxidase (EPO) in the killing mechanism. EOs adherent to FCS-coated plastic wells more than double their production of superoxide anion and the cytotoxic EPO-derived oxidant HOBr when exposed to TNF, showing that TNF activates the respiratory burst of EOs attached to a "physiologic" surface. Unlike PMNs, EOs were not irreversibly activated to kill unopsonized endothelium by previous exposure to TNF, and did not degranulate or upregulate CR3 expression as detected by Mo1 in the presence of 100 U/ml TNF. HUVEC exposed 18 h to TNF were considerably more susceptible to lysis by PMA-activated EOs and reagent H2O2, demonstrating a direct effect of TNF upon endothelium, perhaps through inhibition of antioxidant defenses. These findings suggest that abnormally elevated serum levels of TNF may provoke EOs to damage endothelial cells and thereby play a role in the pathogenesis of tissue damage in hypereosinophilic states.

Antigens, Differentiation↗
PubMed1990

Interactions between a lymphoma membrane-associated guanosine 5'-triphosphate-binding protein and the cytoskeleton during receptor patching and capping.

In this study we have used several complementary techniques to isolate and characterize a lymphoma membrane-associated 41-kDa protein that shares a number of structural and functional similarities with the alpha i subunit of the guanosine 5'-triphosphate (GTP)-binding protein (e.g., Gi alpha-like protein). In addition, using permeabilized lymphoma cells, we have found that: 1) GTP or GTP-tau-S augments, and pertussis toxin inhibits, phospholipase C (PLC) activity and receptor capping; and 2) the addition of lymphoma 41-kDa Gi alpha-like protein stimulates PLC activity and receptor patching/capping, and reverses the inhibitory effect of pertussis toxin on both activity and receptor patching/capping. Additional cytochemical and biochemical data indicate that the lymphoma 41-kDa protein is closely associated with several cytoskeletal proteins (e.g., actin, myosin, and fodrin) all of which colocalize under receptor cap structures. Furthermore, both the 41-kDa-mediated phospholipase C activity and receptor patching/capping are inhibited by cytochalasin D (a microfilament disrupting drug) and W-7 drug (a calmodulin inhibitor). Together, these data provide strong evidence for a functional association between the lymphoma membrane cytoskeleton and the 41-kDa (Gi alpha-like) protein. Specifically, this association appears to be required for the activation of phospholipase C that results in inositol triphosphate production, subsequent internal Ca2+ release, and finally surface receptor patching and capping.

Animals↗
PubMed1990

Dermatomyositis associated with multifocal lipoatrophy.

A 10-year-old boy had juvenile dermatomyositis and multiple asymmetric lesions of lipoatrophy. The lipoatrophy had occurred without preceding clinical evidence of inflammation. Biopsy specimens of the skin confirmed a lobular panniculitis. This is the first report of the association of lipoatrophy and juvenile dermatomyositis.

Buttocks↗
PubMed1990

Membrane-associated 41-kDa GTP-binding protein in collagen-induced platelet activation.

Initially we established that the binding of collagen to human blood platelets stimulates both the rapid loss of PIP2 and the generation of inositol-4,5-bisphosphate (IP2) and inositol-1,4,5-triphosphate (IP3). These results indicate that the binding of collagen stimulates inositol phospholipid-specific phospholipase C during platelet activation. The fact that GTP or GTP-gamma-S augments, and pertussis toxin inhibits, collagen-induced IP3 formation suggests that a GTP-binding protein (or (or proteins) may be directly involved in the regulation of phospholipase C-mediated phosphoinositide turnover in human platelets. We have used several complementary techniques to isolate and characterize a platelet 41-kDa polypeptide (or polypeptides) that has a number of structural and functional similarities to the regulatory alpha i subunit of the GTP-binding proteins isolated from bovine brain. This 41-kDa polypeptide (or polypeptides) is found to be closely associated with at least four membrane glycoproteins (e.g., gp180, gp110, gp95, and gp75) in a 330-kDa complex that can be dissociated by treatment with high salt plus urea. Most important, we have demonstrated that antilymphoma 41-kDa (alpha i subunit of GTP-binding proteins) antibody cross-reacts with the platelet 41-kDa protein (or proteins) and the alpha i subunit of bovine brain Gi alpha proteins, and blocks GTP/collagen-induced IP3 formation. These data provide strong evidence that the 41-kDa platelet GTP-binding protein (or proteins) is directly involved in collagen-induced signal transduction during platelet activation.

Adenosine Diphosphate Ribose↗
PubMed1990

Love and violence: gender paradoxes in volatile attachments.

This article presents a multidimensional, theoretical model for the understanding of relationships in which men are violent toward women. It argues that abusive relationships exemplify, in extremis, the stereotypical gender arrangements that structure intimacy between men and women generally. Moreover, it proposes that paradoxical gender injunctions create insoluble relationship dilemmas that can explode in violence. A multifaceted approach to treatment, which incorporates feminist and systemic ideas and techniques, is described.

Family Therapy↗
PubMed1990

Ultrasonic assessment of injuries to the lateral complex of the ankle.

A prospective study of 114 patients who injured the lateral complex of their ankles. All patients were subjected to ultrasound scanning within 48 h of their injury under double blind conditions. The authors' results suggest that the sensitivity of the ultrasound diagnosis approaches that of conventional radiology, if used properly. Furthermore, ultrasonic scanning is a useful adjuvant to clinical assessment of patients with regards to selection for further radiological examination. A case is also made for firms in the medical physics arena to develop suitable hardware in the diagnostic ultrasonic field for fracture management.

Adolescent↗