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Biomedical subjects

H M Hill

Publications and source records attributed to H M Hill.

At least 19 recordsLinked to original sources
PubMed2001

Divergent roles of glycolysis and the mitochondrial electron transport chain in hypoxic pulmonary vasoconstriction of the rat: identity of the hypoxic sensor.

1. The mechanisms responsible for sensing hypoxia and initiating hypoxic pulmonary vasoconstriction (HPV) are unclear. We therefore examined the roles of the mitochondrial electron transport chain (ETC) and glycolysis in HPV of rat small intrapulmonary arteries (IPAs). 2. HPV demonstrated a transient constriction (phase 1) superimposed on a sustained constriction (phase 2). Inhibition of complex I of the ETC with rotenone (100 nM) or complex III with myxothiazol (100 nM) did not cause vasoconstriction in normoxia, but abolished both phases of HPV. Rotenone inhibited the hypoxia-induced rise in intracellular Ca(2+) ([Ca(2+)](i)). Succinate (5 mM), a substrate for complex II, reversed the effects of rotenone but not myxothiazol on HPV, but did not affect the rise in NAD(P)H fluorescence induced by hypoxia or rotenone. Inhibition of cytochrome oxidase with cyanide (100 microM) potentiated phase 2 constriction. 3. Phase 2 of HPV, but not phase 1, was highly correlated with glucose concentration, being potentiated by 15 mM but abolished in its absence, or following inhibition of glycolysis by iodoacetate or 2-deoxyglucose. Glucose concentration did not affect the rise in [Ca(2+)](i) during HPV. 4. Depolarisation-induced constriction was unaffected by hypoxia except in the absence of glucose, when it was depressed by approximately 50 %. Depolarisation-induced constriction was depressed by rotenone during hypoxia by 23 +/- 4 %; cyanide was without effect. 5. Hypoxia increased 2-deoxy-[(3)H]glucose uptake in endothelium-denuded IPAs by 235 +/- 32 %, and in mesenteric arteries by 218 +/- 38 %. 6. We conclude that complex III of the mitochondrial ETC acts as the hypoxic sensor in HPV, and initiates the rise in smooth muscle [Ca(2+)](i) by a mechanism unrelated to changes in cytosolic redox state per se, but more probably by increased production of superoxide. Additionally, glucose and glycolysis are essential for development of the sustained phase 2 of HPV, and support an endothelium-dependent Ca(2+)-sensitisation pathway rather than the rise in [Ca(2+)](i).

Animals↗
PubMed1997

Children's and parents' perceptions of children's exposure to violence in urban neighborhoods.

This study examined child and parent perceptions of children's exposure to community violence in a sample of 9 to 12 year olds from high- and low-violence neighborhoods in Washington, DC. More than 75% of the African-American elementary school children sampled indicated that they had witnessed incidents of community violence ranging from homicides to nonfatal shootings, physical assaults, gang violence, robbery with assaults, and rape in their neighborhoods. Yet, almost half of the parents in the study denied that their children had been exposed to any community violence. When these discrepancies were examined, results revealed that children whose parents were in disagreement regarding their exposure to community violence were less likely to experience social support from their peers. Parents' possible lack of awareness as to the experience of their children may place them at further risk by eliminating the possibility for adult-child interaction and guidance regarding their experience with violence in their neighborhoods. Recommendations are provided to assist adults in addressing the needs of children exposed to community violence.

Adolescent↗
PubMed1997

Astrocytic reaction in long-term resuscitation.

The brain of 34 subjects who died after prolonged resuscitation (more than 20 days) were studied in order to evaluate the possibility of discriminating original cerebral injuries from changes caused by prolonged resuscitation. We focused our attention on the astrocytic reaction and its relationship to the associated lesions. Twelve of the 34 cases showed astrocytosis picture. Of these 5 were anisomorphic and 7 isomorphic. From the analysis of the various morphological findings, taking into account an individual's clinical history, we can conclude that isomorphic astrocytosis is a typical morphological reaction related to resuscitation duration and it is the result of a slow, gradual neuronal degeneration induced by chronic hypoxia. Anisomorphic astrocytosis, on the other hand, can be an indicator of acute and focal cerebral lesion.

Adult↗
PubMed1995

Relationship between multiple exposures to violence and coping strategies among African-American mothers.

This exploratory study examined the relationship between coping strategies of 136 African-American mothers, their exposure to community violence, and their interpersonal victimization. It is suggested that the disproportionate victimization of African-American women produces a cumulative triple threat for those who live amidst conditions of community violence in the following manner: a) exposure through daily living in the midst of unpredictable community violence; b) exposure to violence from witnessing violence in the neighborhood; and c) exposure to violence from disproportionately high rates of personal victimization. The findings suggest that coping strategies are used differentially as a function of the amount of violence within the social context, and the education and financial resources of the mothers. Mothers who live in lower-violence areas with college education preferred activism as a coping strategy, whereas those in high-violence areas with comparable incomes and education preferred reliance on prayer and instituting safety practices. Coping strategies differed based on whether mothers had been physical victims and witnesses to violence or had no personal experience with violence. This study lays the groundwork for a model of exploring the impact of the cumulative effects of violence on African-American mothers parenting in urban America.

Adaptation, Psychological↗
PubMed1991

Difficult intubation and the Laryngeal Mask.

The Laryngeal Mask (LM) can be used to intubate patients in whom conventional direct laryngoscopy is difficult. Tracheal intubation can be achieved using the LM alone but the use of a fibre-optic laryngoscope increases the chances of success.

Anesthesiology↗
PubMed1990

A liquid chromatographic method for the determination of danazol in human serum.

A liquid chromatographic method for the determination of danazol in human serum has been developed. Reversed-phase C8 and C18 columns were used with a column-switching valve, isocratic elution and UV detection. Sample pretreatment involved extraction of the drug with pentane-methylene chloride. The method enabled the measurement of the drug at a concentration as low as 1 ng ml-1, with precision of 15.0% and accuracy of 8.3%. The method was used to run a two way replicated pharmacokinetic study of danazol. The main pharmacokinetic parameters were (mean of two periods): AUCinf = 480.94 ng x h ml-1, Cmax = 53.2 ng ml-1, tmax = 2.5 h, t0.5 = 18.00 h.

Chromatography, Liquid↗
PubMed1990

Evaluation of criteria for the acceptance of bioanalytical data.

Results from bioanalytical analyses for registration of a new drug entity are used to define its pharmacokinetics and bioavailability/bioequivalence. Whilst analytical data may be derived from the application of a validated method, it is essential to apply mathematical criteria to its acceptance, in order that the analyst can be assured that the assay is performing within defined limits and to its validated specification. Parameters evaluated for acceptability are the batch calibration curve, the minimum quantifiable concentration and the quality control (QC) sample acceptability. Specifically, six QC samples per analytical batch are used, two samples at each of three concentrations. The rationale for the definition of these criteria is evaluated together with a consideration of their applications and limitations. The relevance and use of Shewhart and Cusum plots to monitor assay performance is illustrated.

Biological Availability↗
PubMed1989

Simultaneous determination of flurazepam and its metabolites in human plasma by high-performance liquid chromatography.

A sensitive isocratic high-performance liquid chromatographic method is described, which allows the precise and accurate quantification of flurazepam and four metabolites with a single determination. A pharmacokinetic study was performed on nine volunteers and the main pharmacokinetic data are reported. The method was used to demonstrate that monodesethylflurazepam and didesethylflurazepam are major metabolites in men. One more unidentified flurazepam metabolite was detected.

Administration, Oral↗
PubMed1987

Pyoderma gangrenosum in a kindred. Precipitation by surgery or mild physical trauma.

Five cases of pyoderma gangrenosum occurring in a kindred are presented. Three of the cases occurred after abdominal surgery and tended to be confused with postoperative wound infections. Two cases occurred after superficial injury to the leg and were also thought to represent a peculiar form of cellulitis. None of the patients are known to have any of the underlying diseases usually associated with pyoderma gangrenosum. The cases are presented to alert the physician to this entity and to document the unusual familial occurrence.

Abdomen↗
PubMed1979

Assessment of the Coag-a-Pet Dual Channel in the routine haemostatic laboratory.

The Coag-a-Pet Dual Channel is an instrument which automatically records coagulation test end-points utilizing a photo-optical clot detection system. The instrument and its operation are described in detail. The capability of the instrument to perform tests of oral anticoagulant control, basic coagulation profiles and one-stage factor assays is assessed. In terms of precision and accuracy, the instrument performs well in carrying out the one-stage prothrombin time, Thrombotest, activated partial thromboplastin time using an automated APTT reagent but not kaolin, and one-stage factor assays. The thrombin clotting time can not be measured on this instrument. The instrument is most suitable for batched repetitive tests, reducing observer error and improving laboratory efficiency.

Blood Coagulation Factors↗