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Biomedical subjects

G D Williams

Publications and source records attributed to G D Williams.

At least 73 records · Page 4Linked to original sources
PubMed1991

Abnormal cortical appearances in pediatric renal allografts.

Renal cortical studies were performed in 19 children with renal transplants. There were 10 normal studies and 9 abnormal studies, 8 of which showed multiple large focal peripheral cortical defects. The following factors showed a positive correlation: (a) the ischemia time of the transplant kidney was significantly shorter in patients with normal studies; (b) cadaver grafts were more likely to have abnormal scan appearances than living related donor grafts; and (c) in four of the five patients with double renal arteries, the scans were abnormal in multiple sites. A possible pathophysiologic mechanism to explain these scan appearances is asymptomatic segmental graft infarction secondary to progressive vascular disease. These infarcts may be a long-term sequela of ischemic insult at the time of or prior to the insertion of the renal allograft.

Child↗
PubMed1990

Alcoholic beverage type, recall period effects and functional disability: evidence from the 1983 NHIS.

To replicate a Canada Health Survey (CHS) study that found beer drinking was associated with lower morbidity, National Health Interview Survey (NHIS) data for 19,462 persons were used to examine associations between functional disability and beverage specific ethanol consumption. A functional disability index consisting of morbidity and symptom coping events reported for 2 weeks prior to the NHIS interview was constructed. Alcohol consumption was reported for the same period as disability (coincident recall), or for the 2 weeks prior to the respondent's last drink during the past year (antecedent recall). The analysis controlled for confounders using direct standardization and multiple logistic regression. The results of this investigation were not consistent with the CHS study. Former drinkers and antecedent recall drinkers reported greater disability rates than either non-drinkers or coincident recall drinkers. Antecedent recall drinkers exhibiting a preference for beer and wine were, respectively, 40 and 80 percent more likely to be disabled than non-drinkers. Further, this study found no evidence of a protective effect among any subgroup of drinkers. The finding of a significant interaction between alcohol consumption and alcohol recall period suggests that epidemiologic studies should give greater attention to the classification of drinker groups by proximity of alcohol consumption.

Activities of Daily Living↗
PubMed1990

Alcohol consumption, gender and self-reported hypertension.

This study examines the relationship of alcohol consumption and self-reported lifetime prevalence of hypertension among 19,284 non-institutionalized civilians in the United States. Cross-sectional data from the 1983 National Health Interview Survey, a national probability sample, were examined for each sex separately. Women who report hypertension consumed significantly less alcohol than women who did not report hypertension. Self-reported hypertensive men consumed equal or greater amounts of alcohol than self-reported normotensive men. Alcohol consumption was significantly associated with greater risk of hypertension among men, but not among women. After controlling for other risk factors significant effects for hypertension were found among males who on average consumed more than one drink/day. Beer consumption and spirits consumption above three drinks/day were significant predictors of male hypertension after adjustment for the confounding effects of other alcoholic beverage consumption and other risk factors. This study suggests that alcohol consumption by men who know that they are hypertensive is an important public health concern, with policy implications for targeting prevention efforts.

Adolescent↗
PubMed1989

31P NMR visibility and characterization of rat liver mitochondrial matrix adenine nucleotides.

Compartmentation and NMR visibility of mitochondrial adenine nucleotides were quantitated in isolated rat liver mitochondria respiring on succinate and glutamate in vitro at 8 and 25 degrees C. Intra- and extramitochondrial nucleotides were discriminated by adding the chelator trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid (CDTA). T1 values of about 0.2-0.3 s for magnesium-bound matrix nucleotides were determined. Adenine nucleotide T1 values were influenced by the ionic environment; only magnesium-free ATP T1's were affected by temperature. Intra- and extramitochondrial adenine nucleotide ratios were varied in ATP-loaded mitochondria with added ATP and phosphate using the mitochondrial inhibitors oligomycin and carboxyatractyloside, and adenine nucleotides were quantitated by using NMR and enzymatic analysis. There was good agreement between matrix ATP concentrations (magnesium-bound ATP) calculated by using NMR and standard biochemical techniques. Although matrix ADP could be detected by NMR, it was difficult to quantitate accurately by NMR. The data indicate that mitochondrial ATP is NMR-visible in isolated mitochondria in vitro.

Adenine Nucleotides↗
PubMed1989

Effect of dimethylsulfoxide on human gliomas: correlations between the nuclear magnetic resonance spectra and the transformed phenotypes of the tumor cells.

Prolonged in vitro induction of six established human glioma cell lines with dimethylsulfoxide (DMSO) generated an adherent human fibroblastoid phenotype. The development of contact-inhibited cell growth coincided with the decreased colony-forming potential of these cells in semisolid medium and with the reduction or elimination of tumorigenicity when transplanted in athymic nude mice. These DMSO-induced changes persisted for at least 19 passages after removal of the inducer from the medium. High-resolution natural-abundance 13C nuclear magnetic resonance spectroscopy showed specific spectral differences between the cell lines with more or less malignant transformed phenotypes: the glioma cells with a higher degree of tumorigenicity and colony-forming potential exhibited more intense myoinositol signals than those with the more benign phenotype.

Animals↗
PubMed1987

Physical heterogeneity of neisserial lipooligosaccharides reflects oligosaccharides that differ in apparent molecular weight, chemical composition, and antigenic expression.

We studied the oligosaccharides (OS) of outer membrane lipooligosaccharides (LOS) of Neisseria gonorrhoeae and Neisseria meningitidis. OS from the LOS of an individual neisserial strain always eluted from Sephadex G-50S as multiple peaks; the polyacrylamide gel elution profiles were nearly identical to the polyacrylamide gel electrophoresis profiles of the sodium dodecyl sulfate-disaggregated native LOS from which the OS were derived. Neisserial OS coeluted with Dex14 to Dex27 dextran oligomers (Mr, 2,210 to 4,320). Monosaccharide composition varied among the several OS released from the LOS of a single strain. The two OS of a gonococcal strain sensitive to normal human serum (NHS) bacteriolysis (sers) varied in their ability to inhibit the binding of NHS immunoglobulin M to their parental LOS. The OS that was rich in hexosamines inhibited NHS immune lysis of its parent strain; the OS that was poor in hexosamines did not. We conclude that structural differences in their OS account for the Mr heterogeneity of the LOS of a strain.

Acetates↗
PubMed1987

Effects of leukotriene B4 inhalation. Airway sensitization and lung granulocyte infiltration in the guinea pig.

Male Hartley guinea pigs were exposed by inhalation to leukotriene B4 (LTB4) and challenged 5 min or 4 h later with bronchoconstrictive aerosols of histamine or the divalent cationic ionophore A23187. Pulmonary gas trapping measured in excised lungs indicated the severity of post-challenge airway obstruction. Airway granulocyte infiltration was scored by an observer who was unaware of animal assignments. Treatment with LTB4 produced a marked influx of eosinophils and neutrophils into tracheal and bronchial airways. Granulocyte scores for LTB4-treated groups were 1.9 to 3.3 times higher than those for vehicle-treated groups at 5 min after exposure and 3.3 to 10.7 times higher at 4 h after exposure. Leukotriene B4 itself did not produce hyperinflation. However, histamine-induced gas trapping was increased 5 min after LTB4 exposure. Histamine responsiveness was unaffected 4 h after LTB4 treatment. In contrast, A23187-induced gas trapping was unaffected at 5 min, but diminished at 4 h after LTB4. Nonchemotactic stereoisomers of LTB4 did not produce granulocyte influx, but did produce altered airway responses similar to those seen for LTB4. We conclude that inhaled LTB4 produces airway granulocyte infiltration in the guinea pig and alterations in airway responsiveness that vary with the challenge stimulus and time after exposure. Alterations in airway responses may result from granulocyte-independent effects of LTB4 and its stereoisomers.

Aerosols↗
PubMed1985

Membrane NMR: a dynamic research area.

Recent NMR relaxation studies of lipid bilayers and biomembranes are explained and briefly discussed. The results of both 2H and 13C NMR investigations suggest that, in addition to rapid local fluctuations of the hydrocarbon chains, slower, more collective motions of the bilayer exist. When the influence of the latter is recognized and properly accounted for, the contribution from local motions can be used to estimate a value for the microviscosity of the bilayer which corresponds to that of a simple n-paraffinic liquid. In general, the dynamic behavior of lipid bilayers as studied by NMR appears quite similar to that of simpler liquid crystals.

Animals↗
PubMed1985

Characteristics of the outer membrane of selected oral Bacteroides species.

The outer membranes from selected oral Bacteroides species were isolated and characterized morphologically, chemically, and physically. Both sucrose density gradient centrifugation and sodium dodecyl sulfate--polyacrylamide gel electrophoresis (SDS-PAGE) revealed outer membranes which varied slightly with the species, as well as showing complex polypeptide patterns after SDS--PAGE. The polypeptide distribution revealed a species-specific pattern; however, there was often a variation within a given species in many minor polypeptide bands, with heat-modifiable minor peptides occurring in nearly all species. Protein-associated carbohydrates occurred in several species. Outer membrane fragments (blebs) recovered by ultracentrifugation of the growth supernatants were either nearly identical to the outer membrane polypeptide patterns, or contained reduced amounts of specific polypeptides, again varying with the species. 125I-labelling of whole cells indicated possible surface exposure for several of the major polypeptides.

Autoradiography↗
PubMed1985

Reliability of self-reported alcohol consumption in a general population survey.

Reliability estimates for the measures of alcohol consumption used in a household survey were examined. Respondents who had not consumed any alcohol within the previous year and those under age 18 were excluded from the survey, yielding a sample of 1395 (48% men). With one survey that involved a 2-week recall period and another that involved a 4-week period, three methods for estimating reliability were employed: alternate forms, test-retest and a combined method. Validity was also examined using a 30-day drinking diary as a criterion. The findings indicate high levels of reliability, averaging .91 for the consumption measures of beer, wine and distilled spirits. Validity estimates were also fairly substantial but not uniformly so across the different beverage types. In general, the results suggest that these consumption measures can be used with considerable confidence.

Adult↗
PubMed1984

Malignant transformation in a plexiform neurofibroma of the median nerve.

A malignant schwannoma of the median nerve occurred in a 27-year-old woman with multiple neurofibromatosis (von Recklinghausen's disease). A growth had been present at the left wrist since birth and was partially excised at the age of 10 years. The patient refused an amputation and radical local excision did not control this highly malignant tumor.

Adult↗
PubMed1983

New view of lipid bilayer dynamics from 2H and 13C NMR relaxation time measurements.

Natural abundance 13C spin-lattice (T1) relaxation time measurements are reported for unilamellar vesicles of 1,2-dipalmitoylphosphatidylcholine (1,2-dipalmitoyl-sn-glycero-3-phosphocholine), in the liquid crystalline phase, at magnetic field strengths of 1.40, 1.87, 2.35, 4.23, 7.05, 8.45, and 11.7 tesla (resonance frequencies of 15.0, 20.0, 25.1, 45.3, 75.5, 90.5, and 126 MHz, respectively), and the results are compared to previous 2H T1 studies of multilamellar dispersions. For both the 13C and 2H T1 studies, a dramatic frequency dependence of the relaxation was observed. At superconducting magnetic field strengths (4.23-11.7 tesla), plots of the 13C T1(-1) relaxation rates as a function of acyl chain segment position clearly reveal the characteristic "plateau" signature of the liquid crystalline phase, as found previously from 2H NMR studies. The dependence of T1(1) on ordering, determined previously from 2H NMR, and the T1(-1) dependence on frequency, determined from both 13C and 2H NMR studies, suggest that a unified picture of the bilayer molecular dynamics can be provided by a simple relaxation law of the form T1(-1) approximately equal to A tau f + BS2C-H omega -1/2(0). In the above expression, A and B are constants, SC-H (= SC-D) is the bond segmental order parameter, and omega 0 is the nuclear Larmor frequency. The first (A) term includes contributions from fast, local segmental motions characterized by the effective correlation time tau f, whereas the second (B) term describes slower, collective fluctuations in the local ordering. The value of tau f approximately equal to 10(-11) sec, obtained by extrapolating T1(-1) to infinite frequency, suggests that the segmental microviscosity of the bilayer hydrocarbon region does not differ appreciably from that of the equivalent n-paraffinic liquids of similar chain length.

Carbon Isotopes↗
PubMed1982

Immunological basis of serum resistance of Neisseria gonorrhoeae.

The immunological basis for resistance of certain strains of Neisseria gonorrhoeae to the bactericidal action of normal human serum was studied by investigating the potential role of factors which are known to interfere with each of the sequential steps that result in immune lysis of Gram-negative bacteria. Strains of N. gonorrhoeae were characterized as serum-sensitive (sers) or serum-resistant (serr) on the basis of their sensitivity to lysis by the sera of six normal individuals. Neither intrinsic resistance to the lytic action of activated human complement nor inaccessibility of the cell membrane to C5b accounted for serr. Outer membrane lipopolysaccharide (LPS) was the target antigen for lytic antibody in normal human sera. The gross chemical composition and molecular size of the LPS of the strains were heterogeneous and no consistent patterns of differences between those extracted from serr and from sers strains were found. Neither IgA nor IgG 'blocking' antibody in normal human serum was responsible for serr. We conclude that serr results from the absence from the LPS of the strains of antigenic loci for the lytic antibody in most normal human sera, or, expressed as a function of the host, the absence from the sera of most normal humans of lytic antibody directed against LPS antigenic loci for immune lysis.

Antibodies, Bacterial↗
PubMed1980

The gluteus maximus myocutaneous flap in the management of pressure sores.

The gluteus maximus myocutaneous flap is modified to obviate the necessity of a skin graft to the donor defect. This is a sufficiently large flap which, in the event of a recurrence, can be rerotated. The design and surgical technique of this flap for ischial and sacral pressure sores are described. This flap was used for 36 pressure sore without loss of any portion of the flap.

Buttocks↗