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Biomedical subjects

A Pratt

Publications and source records attributed to A Pratt.

12 recordsLinked to original sources
PubMed1998

Impaired glycolysis and protein catabolism induced by acid in L6 rat muscle cells.

BACKGROUND: In skeletal muscle, metabolic acidosis stimulates protein degradation and oxidation of branched-chain amino acids. This could occur to compensate for impairment of glucose utilization induced by acid. METHODS: To test this hypothesis, glycolysis and protein degradation (release of [14C]-phenylalanine) were measured in L6 skeletal muscle cells cultured in Eagle's minimum essential medium at pH 7.1 or 7.5 for up to 3 days. RESULTS: No marked changes in total DNA or in cell viability were detected, nor was there any significant effect on intracellular pH or the water content of the cells (which is thought to be a key regulator of protein turnover, especially in liver). In spite of this, acid stimulated protein degradation, induced net protein loss from the cultures, inhibited glucose uptake and glycolysis (lactate output) and was associated with increased [1-14C]-leucine oxidation. Effects on protein degradation and glycolysis were gradual, reaching a maximum after 20-30 h. To investigate whether glycolytic flux itself can influence protein degradation, increased glycolysis was simulated by adding glucose (20 mmol L-1) or pyruvate (1 mmol L-1) to the medium. At pH 7.1, neither addition had any effect on protein degradation. CONCLUSION: Although acid-induced protein wasting is associated with impaired glycolysis, no obligatory coupling exists between glycolytic flux and protein degradation.

Acidosis↗
PubMed1996

Moral and social reasoning and perspective taking in later life: a longitudinal study.

In this study 27 older adults (ages 64-80) and 23 middle-aged adults (ages 35-54) were tested for moral stage, integrative complexity of social reasoning, and perspective-taking levels twice over a 4-year period. Moral reasoning stage levels did not change over time for either age group. Older adults, but not the middle-aged, showed a significant decline over time in level of moral perspective taking. Complexity of reasoning about several interpersonal social issues declined modestly in both age groups. More social-cognitive support, a higher education level, and better self-reported health were all found to be protective factors in forestalling declines in mature adults' sociocognitive reasoning, consistent with other research on cognitive measures in later life.

Adult↗
PubMed1989

Multiple plasma exchanges successfully maintain a young adult patient with Crigler-Najjar syndrome type I.

Plasmapheresis has been shown to reduce total and free bilirubin levels in acute exacerbations of Crigler-Najjar syndrome, type I (CNS-TI), but its effectiveness in long-term management has not been reported. An 18-year-old (yo) male with CNS-TI, who required prolonged daily high-intensity phototherapy to prevent cerebral nervous system symptoms, developed increasingly frequent bouts of confusion, nausea, and vomiting associated with free bilirubin concentrations (fbcs) greater than 10-15 nmol/L. Pending consideration of orthotopic liver transplantation, plasma exchange (approximately 3 liters per procedure) was begun in 12/84 using the IBM/COBE 2997 with 5% albumin as replacement fluid. Frequency of treatments was guided by twice weekly fbcs, with plasma exchange for fbc greater than 10-15 nmol/L. Pre-exchange and postexchange fbcs ranged from 27.5 to 11 nmol/L and 9.2 to 2 nmol/L, respectively. Seventy-two exchanges were performed over a 28 month period. Irreversible CNS damage did not occur, and the patient underwent successful liver transplantation in April of 1987, with complete correction of his metabolic disorder. He remains well 18 months following transplantation.

Adolescent↗
PubMed1987

Electrically evoked skin vasodilatation: a quantitative test of nociceptor function in man.

Direct stimulation of intact forearm skin affects adjacent microvascular blood flux. Pulses of current, known to activate C-fibres effectively, were applied over a period of 1-16 seconds at 2 Hz using transcutaneous stimulation. An increase of up to 50% was observed in skin microvascular blood flux. Increased blood flux correlated well with increasingly painful sensations. Some subjects responded to one or two pulses at 2 Hz, 0.5 ms in duration and 150 volts. A response onset latency of 4-15 s, lasting up to 5 minutes, was recorded. At higher frequencies (4-8 Hz) and more pulses (16-32) vasoconstriction was frequently observed before the usual flux increase. After administration of local anaesthesia (2% ligocaine) the resting skin blood flux increased, but electrical stimulation still produced vasodilatation. The local cutaneous flare response to electrical stimulation was abolished or greatly reduced by capsaicin pretreatment. Excitation of small intracutanous forearm nerve C-fibres produces increased microvascular blood flux which is dependent on local release of vasodilator substances. Thus the neurogenic flare (axon reflex) may have a physiological role in regulating skin blood flow, and nociceptor function may be measured by applying the aforementioned transcutaneous electrical stimulation.

Axons↗
PubMed1984

Cytochalasin B facilitates the inhibition of human polymorphonuclear leukocyte generation of superoxide by verapamil.

Several functions of the human neutrophil are dependent upon extracellular calcium for optimal activation. We studied the calcium dependency of human polymorphonuclear leukocyte (PMN) superoxide generation in response to opsonized zymosan particles and its modulation by the calcium channel antagonist verapamil. PMNs were isolated from anticoagulated blood after Ficoll-Hypaque density centrifugation. The isolated PMNs were incubated with opsonized zymosan particles. The superoxide anion generated was measured by a cytochrome C reduction assay. When PMNs were incubated with opsonized zymosan in a calcium-free buffer, there was 0.45 +/- 0.06 nmol of cytochrome C reduced per 1 X 10(6) PMN per minute. This increased to 0.76 +/- 0.12 nmol per 1 X 10(6) PMN per minute when 0.6 mmol/L Ca++ was present. Moreover, if the PMNs were incubated with cytochalasin B (5 micrograms/ml), the generation of superoxide anion was further enhanced. If the same experiments were conducted in the presence of verapamil, 100 mumol/L, superoxide generation was inhibited by 51.5% +/- 8.4%. For verapamil to inhibit superoxide generation, cytochalasin B was necessary. Our results suggest that verapamil-sensitive calcium channels may exist in human PMNs, and the demonstration of their presence is cytochalasin B-dependent.

Calcium↗
PubMed1979

A quantitative sutdy of vertebral displacement and angulation in the normal cervical spine under axial load.

Cervical traction of one-third the person's weight was applied for 3 minutes to normal subjects. The mean and standard deviation of displacement and rotation between adjacent cervical vertebra was calculated in the sagittal plane. The average separation between adjacent vertebra was 0.7 mm with a standard deviation of 0.5 mm. The average angular motion between adjacent vertebra was 0.9 degrees with a standard deviation of 2.4 degrees.

Adult↗
PubMedDate not supplied

Case management services for adolescent substance abusers: a program description.

A case management model for adolescent substance abusers whose problems are severe enough to warrant residential treatment is presented, based on the experience of a demonstration project. The five integral functions of case management (assessment, planning, linking, advocacy, and support) are described within the framework of each phase of an adolescent's treatment program (screening, residential treatment, and continuing care). Detailed descriptions of case management activities and the philosophy underlying case management are addressed. The integrated client tracking and program evaluation monitoring system developed for the case management project is described, and evaluation data are presented. Among the advantages case managers are able to offer to the entire treatment process include encouragement of family involvement in the youth's recovery; providing support; tracking substance abuse relapse episodes following treatment; connecting the youth with school, work, and community resources; and helping youth to fulfill legal obligations.

Adolescent↗
PubMedDate not supplied

Prospective study of transbronchial biopsies in the management of heart-lung and single lung transplant patients.

A prospective study of 219 bronchoscopies in 54 heart-lung and in 2 single lung transplant recipients was undertaken over a 12-month period by a single operator. For histologic study, an average of 17.3 transbronchial biopsy specimens (range, 6 to 56) were taken from three lobes (or from two lobes and lingula of one lung). A further two specimens were taken for culture. The average procedure time was 14.4 minutes (SE 0.31). An estimate of the probability of rejection being missed, depending on the number of specimens taken and based on the method of Gilman and Wang, suggests 18 biopsy specimens are required to have 95% confidence of diagnosing rejection. Sensitivity for diagnosing rejection by histologic study of transbronchial biopsy specimens was 94%, and specificity was 90%. The simple grading of severity of rejection that was used was related both to the number of specimens demonstrating rejection and to the severity of graft airway mucosal inflammation seen at bronchoscopy. The major complication encountered, on 27 occasions, was bleeding of more than 100 ml. On no occasion did bleeding result in any long-term complication. Extensive transbronchial biopsy is a simple, relatively safe, and quick procedure, with a high sensitivity and specificity for diagnosing rejection and lung infection.

Adolescent↗