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Biomedical subjects

D Williams

Publications and source records attributed to D Williams.

At least 379 records · Page 21Linked to original sources
PubMed1991

In vitro testing of a potentially biocompatible continuous ambulatory peritoneal dialysis fluid.

In the present study a newly formulated dialysis solution (HDF) was tested for its effects on phagocyte viability and function as well as its ability to support bacterial growth. This solution differs from standard CAPD solution (NPD) by the inclusion of histidine to buffer the fluid to pH 6.7. Low-dextrose HDF (1.36% w/v dextrose) did not significantly decrease the viability or inhibit any of the PMN functional parameters measured (phagocytosis, LTB4 release or respiratory burst activation) when compared to control buffer. NPD (1.36% w/v dextrose) at low pH as well as all high-dextrose dialysis solutions (NPD and HDF) significantly inhibited most PMN functions independently of reduced viability. Peritoneal mesothelial cell viability was unaffected by either low- or high-dextrose HDF but was significantly reduced by NPD (1.36 and 3.86% dextrose) at pH 5.2. The inhibitory effects of low dextrose dialysis solutions were confirmed as being partly related to their low initial pH. High-dextrose dialysis fluids, however, inhibit PMN function by a mechanism which, in addition to initial pH, appears to be directly related to their dextrose content but not their osmolality.

Bacteria↗
PubMed1991

The cytotoxin of Actinobacillus pleuropneumoniae (pleurotoxin) is distinct from the haemolysin and is associated with a 120 kDa polypeptide.

Mutants of Actinobacillus pleuropneumoniae strain HK 361 (serotype 2) were isolated which were deficient in type II (Ca2(+)-dependent) haemolysin activity (Hly-). Some of the Hly- mutants secreted a potent, heat-labile extracellular cytotoxic activity against porcine alveolar macrophages. Comparison of cell-free culture supernatant from the parent strain and some Hly- mutants by SDS-PAGE and immunoblotting revealed the loss of a major extracellular polypeptide of 109 kDa. Two Hly- mutants which in addition failed to secrete a 120 kDa polypeptide produced no extracellular cytotoxic activity, suggesting that the 120 kDa protein was the cytotoxin. Antiserum raised to the culture supernatant from a Hly- mutant lacking the 109 kDa polypeptide recognized the 120 kDa band, but not the 109 kDa band, in immunoblots and neutralized the cytotoxic activity, but not the haemolytic activity, of A. pleuropneumoniae. The 120 kDa polypeptide and extracellular cytotoxic activity were widespread among A. pleuropneumoniae strains, but absent from related bacterial pathogens of the pig: Actinobacillus suis, Haemophilus parasuis and Pasteurella multocida. A clear correlation was found between the presence of the 120 kDa polypeptide and cytotoxic activity in culture supernatants. The cytotoxic activity of all the strains tested was neutralized by antibody to the Hly- extracellular material and by convalescent pig serum. It is proposed that the 120 kDa polypeptide represents the cytotoxin of A. pleuropneumoniae, that it is distinct from the haemolysin, and that it be termed pleurotoxin.

Actinobacillus↗
PubMed1991

An evaluation of the impact of maternity care coordination on Medicaid birth outcomes in North Carolina.

BACKGROUND: Care coordination is an important component of the enhanced prenatal care services provided under the recent expansions of the Medicaid program. The effect of maternity care coordination services on birth outcomes in North Carolina was assessed by comparing women on Medicaid who did and did not receive these services. METHODS: Health program data files, including Medicaid claims paid for maternity care coordination, were linked to 1988 and 1989 live birth certificates. Simple comparisons of percentages and rates were supplemented by a logistic regression analysis. RESULTS: Among women on Medicaid who did not receive maternity care coordination services, the low birth weight rate was 21% higher, the very low birth weight rate was 62% higher, and the infant mortality rate was 23% higher than among women on Medicaid who did receive such services. It was estimated that, for each $1.00 spent on maternity care coordination, Medicaid saved $2.02 in medical costs for newborns up to 60 days of age. Among the women who did receive maternity care coordination, those receiving it for 3 or more months had better outcomes than those receiving it for less than 3 months. CONCLUSIONS: These results suggest that maternity care coordination can be effective in reducing low birth weight, infant mortality, and newborn medical care costs among babies born to women in poverty.

Continuity of Patient Care↗
PubMed1991

Diagnosis and treatment of tinea pedis. A review and update.

Fungal foot infections are becoming an increasingly common public health problem as the population ages. New studies have shown that some of the traditional therapeutic antifungal agents have multiple actions that enable them to be more efficacious than previously thought, and more efficacious than other agents without multiple actions. In this review article, the pedal infections commonly referred to as tinea pedis, or athlete's foot, are described. The etiologic agents involved in the pathogenesis, the methodologies for proper diagnosis, and the therapeutic agents commercially available for treatment are reviewed.

Antifungal Agents↗
PubMed1991

Evaluation of a comprehensive algorithm for blunt and penetrating thoracic and abdominal trauma.

The objective was to develop a single branched-chain decision tree for both blunt and penetrating thoracic and abdominal trauma and to test its feasibility to track clinical decisions. The algorithm consisted of 14 specific patient management loops and 31 decision nodes. During a 4-month period, the management decisions and clinical course of 434 trauma patients were prospectively observed. Thirty-four patients had no signs of life on arrival to the emergency department (ED) and were excluded from the statistical evaluation; the remaining 400 patients constituted the study group. The mean Injury Severity Score (ISS), Penetrating Abdominal Trauma Index (PATI), and Trauma Score (TS) scores in the series were 21 +/- 10, 34 +/- 12, and 13 +/- 3. The overall patient mortality of the study group was 17 per cent; it was 61 per cent in those patients with major deviations from the algorithm and 6 per cent in patients who complied with the algorithm. The ISS, PATI, and TS scores were 29 +/- 9, 32 +/- 12, and 13 +/- 2 in patients with deviations and 20 +/- 10, 37 +/- 12, and 14 +/- 2 in patients who complied with the algorithm. Of the 37 patients who died with major deviations from the algorithm, the deviation was directly contributory to death in 21 cases (57%) and probably contributory in another 14 cases (38%). There were 108 patients with ISS scores between 20 and 50. In this group, mortality was 55 per cent when a major deviation occurred and 5 per cent without major deviations from the algorithm. The authors conclude that the survival of trauma patients may be improved by following the specific management criteria outlined by the algorithm.

Abdominal Injuries↗
PubMed1991

The relationship between ARDS, pulmonary infiltration, fluid balance, and hemodynamics in critically ill surgical patients.

Hypervolemia from fluid overload with resultant pulmonary edema is thought to be a frequent cause of Adult Respiratory Distress Syndrome (ARDS). However, ARDS may also occur as a result of the hypovolemic shock of surgery or trauma. To develop an appropriate rationale for fluid therapy in high-risk surgical patients, the relationship between fluid balance, hemodynamics, the onset of ARDS by physiologic criteria (shunt greater than or equal to 20%, and/or PaO2/FiO2 ratio less than 250) and the onset of pulmonary infiltration (PI) associated with ARDS were examined. Fifty patients were prospectively followed from admission throughout their hospitalizations; 38 (76%) had trauma and 12 (24%) were postoperative. Cardiac index, central venous pressure (CVP), wedge pressure (WP), and shunt (Qsp) were measured. All chest x rays were read by one staff radiologist who was blinded to the patients' identities. PI was graded from "0" to "4" (0 = no PI, 4 = maximum PI). The first x ray reading of "2" or greater was used as the time of onset of PI. ARDS by physiologic criteria occurred in 29 of 50 (58%) patients; 27 of these 29 (94%) also developed +2 or greater PI. The mean onset times of ARDS and of +2 PI were 40 +/- 41 hours and 40 +/- 38 hours, respectively. The ARDS patients had a significantly smaller net positive fluid balance than the non-ARDS patients over the first 40 hours after admission (+6,831 ml +/- 4,909 ml vs 12,440 ml +/- 7,817 ml, (P less than 0.01)).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Evaluation of a blunt and penetrating trauma algorithm for truncal injury.

The authors objective was to develop and test a single branch-chain decision tree for blunt and penetrating truncal injury. Over the 4-month study period there were 979 patients evaluated in the emergency department; 674 of these patients were admitted to the hospital. Thirty-four (5%) of the 674 admitted patients died of truncal injury. The study group consisted of 239 of the most severely injured patients; 41 of these (17%) died. Of the 44 patients managed with major deviations from the algorithm, 27 (61%) died. Only 14 of the 195 patients (7%) whose management complied with the algorithm died. The authors conclude that following the specific management criteria outlined by the algorithm may improve the survival of severely traumatized patients.

Abdominal Injuries↗
PubMed1990

Differential augmentation by recombinant human tumor necrosis factor-alpha of neutrophil responses to particulate zymosan and glucan.

Zymosan (Z) and its major insoluble carbohydrate component beta-linked glucan activate human neutrophils (PMN) through a trypsin-sensitive recognition mechanism. This mechanism is believed to involve the PMN CR3R. Both Z and glucan generated dose and time-dependent release of the secondary lysosomal granule marker vitamin B12 binding protein, leukotriene B4 (LTB4) and superoxide from PMN and were phagocytosed with similar dose-dependent kinetics. The PMN superoxide and LTB4 responses to glucan; however, were consistently greater than those to the same doses of Z. The phagocytosis of both particles was significantly reduced after partial digestion with beta-laminarinase but not beta-glucosidase or alpha-mannosidase suggesting a recognition mechanism dependent on intact beta-1,3-glucosidic bonds in both particles. TNF-alpha (rhTNF-alpha) promoted a time- and dose-dependent increase in the expression of PMN CR3 up to 60 min. The increased expression of CR3 was paralleled by the release of the secondary lysosomal granule marker vitamin B12-binding protein. This granule contains a population of CR3R in its boundary membrane and it is the fusion of this membrane with the plasma membrane that may represent the mechanism by which CR3 expression is increased. Preincubation of PMN with 10(-9)M rhTNF-alpha augmented phagocytosis, LTB4, and superoxide generation by PMN in response to activation by Z. In contrast, none of the responses to glucan was significantly increased after incubation with rhTNF-alpha. These differences suggest a lack of absolute homology between the recognition mechanisms for zymosan and glucan and that there is a component of the recognition mechanism for zymosan that is independent of that for glucan and is up-regulated after rhTNF-alpha pretreatment.

Glucans↗
PubMed1990

Fatty acids on the A/Japan/305/57 influenza virus hemagglutinin have a role in membrane fusion.

The covalent attachment of fatty acid moieties to proteins is a widespread post-translational modification of viral and cell proteins yet the functional consequences of acylation are not well understood. We have determined that the A/Japan/305/57 influenza virus hemagglutinin (HA) contains three potential acylation sites at cysteine residues 211, 218 and 221 in the cytoplasmic domain of the molecule. Site-directed mutagenesis of one or more of these sites has no effect on biosynthesis, transport or receptor binding activity of the molecule; however, modification of any single site is sufficient to abolish completely or inhibit severely membrane fusion activity, a function essential for virus infectivity. We present a molecular model of the transmembrane and cytoplasmic domains of the HA to illustrate the potential orientation of these fatty acids and to provide a conceptual framework for further experimentation.

Acylation↗