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Biomedical subjects

A Pope

Publications and source records attributed to A Pope.

At least 19 recordsLinked to original sources
PubMed1992

Recovery from experimental parkinsonism in primates with GM1 ganglioside treatment.

A parkinsonian syndrome can be produced in nonhuman primates by administration of the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Parkinsonian-like symptoms induced acutely by MPTP were ameliorated after treatment with GM1 ganglioside, a substance shown to have neurotrophic effects on the damaged dopamine system in rodents. Treatment with GM1 ganglioside also increased striatal dopamine and metabolite levels and enhanced the dopaminergic innervation of the striatum as demonstrated by tyrosine hydroxylase immunohistochemistry. These results suggest that GM1 ganglioside may hold promise as a therapeutic agent for the treatment of Parkinson's disease.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1989

Diaphragm metabolism during supramaximal phrenic nerve stimulation.

The metabolic changes accompanying diaphragm fatigue caused by supramaximal stimulation of the phrenic nerves are incompletely described. In particular, we wished to determine whether the occurrence of anaerobic metabolism correlated with fatigue as defined by decline in force generation. In 10 anesthetized mechanically ventilated mongrel dogs we measured arterial pressure, transdiaphragmatic pressure (Pdi), phrenic arterial flow (Qdi-Doppler flow probe), arterial and phrenic venous blood gases, and lactate levels. From these we derived indexes of diaphragm O2 consumption (VO2) and lactate production. Bilateral phrenic nerve pacing was carried out (50 Hz, duty cycle 0.4, 24 contractions/min) for two 15-min pacing periods separated by a 45-min rest period. Over each pacing period Pdi decreased from approximately 16 to approximately 10 cmH2O (P less than 0.01, no significant difference between periods). Initially, during pacing, Qdi and VO2 each increased fivefold over prepacing base line. Qdi remained elevated at this level whereas VO2 decreased over the pacing period by approximately 25%. Hence, the change in VO2 over the pacing period was due primarily to changes in O2 extraction. During the first pacing period lactate production was observed early and declined throughout the pacing period. No lactate production was observed during the second pacing period, although Pdi, VO2, and Qdi responses were the same for both pacing periods. Phrenic venous PO2 remained greater than 30 Torr throughout both pacing periods.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Naloxone does not alter response to hypercapnia or resistive loading in chronic obstructive pulmonary disease.

To assess the role of endogenous opioid peptides in ventilatory control in patients with chronic obstructive lung disease, we measured the ventilatory and mouth occlusion pressure responses to hypercapnia and the compensatory response to an inspiratory resistive load in 11 male patients with COPD before and after intravenous administration of naloxone or placebo on 2 separate days. There were no statistically significant differences between naloxone and placebo administration in any index of ventilatory response to CO2 or resistive loading. When an inspiratory resistive load was added during CO2 rebreathing, minute ventilation at PETCO2 = 50 mm Hg in all 11 patients decreased significantly (p less than 0.05) with placebo and naloxone. In response to the inspiratory resistive load, in eight of the 11 patients mouth occlusion pressure (P0.1) did not increase; these eight subjects were classified as noncompensators. Naloxone did not affect the P0.1 response to inspiratory resistive loading, either in the group as a whole or in the subgroup of eight patients classified as noncompensators. Our study was unable to demonstrate that increased activity of endogenous opioid peptides suppresses the ventilatory response to CO2 or resistive loading in patients with chronic obstructive lung disease.

Aged↗
PubMed1987

Inversion polymorphism in species of the Drosophila nasuta subgroup from Thailand.

Thailand populations of three species of the D. nasuta complex have been analysed for the presence of paracentric inversions. D. albomicans and D. sulfurigaster albostrigata were collected from Phuket, Chiang Mai and the River Kwai, whilst D. kohkoa was found only in Phuket and the River Kwai. Chromosomal polymorphism was studied in respect to geographical distribution. The Phuket populations of all three species proved to be highly polymorphic by comparison with the River Kwai and Chiang Mai populations. The heterozygosity frequencies of inversions were calculated and the variations interpreted as a result of adaptation to local ecogeographical conditions. Shared polymorphisms revealed that D. kohkoa and D. s. albostrigata are more closely related to D. albomicans than they are to each other.

Animals↗
PubMed1987

Detection of hypercapnia by normal subjects.

1. To investigate whether changes in PaCO2 can be detected independently of the CO2-induced changes in pulmonary ventilation, we tested five normal subjects for the ability to distinguish different levels of end-tidal PCO2 (PETCO2) while holding minute ventilation constant. 2. Helped by a visual feedback system, the subjects maintained a constant ventilation targeted at a level that was higher than that dictated by the chemical drive at PETCO2 = 50 mmHg (6.7 kPa). End-tidal PCO2 was held at 40 mmHg (5.3 kPa) during the first 2 min of each test trial ('control period'); then, for 4 min ('test period'), PETCO2 was either elevated to 50 mmHg or kept at 40 mmHg. Twelve runs were performed by each subject. 3. In 24 out of the total 30 trials (80%) in which PETCO2 was raised during the test period to 50 mmHg, the subjects detected the changes. There was one false positive result (3%), when PETCO2 kept at 40 mmHg during the test period was reported as different from control. In four out of the five subjects the ability to detect the change in PETCO2 from 40 to 50 mmHg was statistically significant. 4. We conclude that increases in PETCO2 can be detected independently of changes in the absolute level of ventilation.

Carbon Dioxide↗
PubMed1987

Cold facial stimulation reduces breathlessness induced in normal subjects.

Patients with breathlessness commonly describe subjective relief when seated near an open window or in front of a fan. Previous studies suggest that a flow of air or application of cold solutions to the face, nasal mucosa, or pharynx may alter ventilation. We hypothesized that a flow of cold air directed against the cheek would reduce the sensation of breathlessness associated with loaded breathing. Sixteen subjects breathed on a device with an inspiratory resistive load (63 cm H2O/L/s) while PCO2 was maintained at 55 torr for 5 min. All studies were performed 4 times with each subject, twice with cold air directed against the cheek (4 degrees to 10 degrees C, 4 km/h) and twice with no flow on the subject. Subjects were asked to rate their breathlessness using a modified Borg scale. Cold air directed on the face reduced breathlessness induced by an inspiratory resistive load and hypercapnia (6.2 +/- 1.7 Borg scale units with no flow, 5.1 +/- 1.7 with cold air; p less than 0.002) without causing a significant reduction in ventilation. This effect was not observed when cold air was directed to the leg and does not appear to be associated with a reduction in the ventilatory response to hypercapnia or with initiation of the diving reflex. We conclude that cold air directed against the cheek significantly reduces dyspnea associated with the combination of hypercapnia and an inspiratory resistive load.

Adult↗
PubMed1985

Bereavement counselling after sudden infant death.

Of 14 families who suffered a sudden infant death, eight were followed up intensively over several months and offered individual counselling, parents' group meetings, and interviews with doctors as a way of helping them come to terms with their feelings of loss. Five couples accepted short term support from their health visitor, and one refused help. Many families experienced considerable stress including marital conflict, difficulties with surviving children, and anxiety about future children becoming victims of the sudden infant death syndrome. It was concluded that medical social workers, health visitors, hospital paediatricians, general practitioners, and parent self help groups are in key positions to help. The success of such help is likely to depend on the confidence that each helper has that his or her contribution will be valued by the bereaved family.

Counseling↗
PubMed1984

Proteases of human brain.

Growing appreciation of the multiple functions of proteolytic enzymes in intracellular protein degradation and post-translational modification, in the release of biologically active macromolecules and peptides from precursors and in cellular protein regulation and quality control has stimulated interest in proteases in neurobiology and neuropathology. In this article, the proteinases and peptidases thus far studied in the human central nervous system are reviewed with respect to their enzymology, anatomical and cytological distributions and contributions to neurological and psychiatric disease states. Though information concerning brain proteases in man is fragmentary, it suffices to establish the importance of these complex systems for advancing knowledge of human cerebral function in health and disease.

Binding Sites↗
PubMed1981

Protease activities in normal and schizophrenic human prefrontal cortex and white matter.

Endo- and exopeptidase activities have been measured post-mortem human prefrontal cortex and subjacent white matter to estimate their relative capabilities for protein and peptide degradation. Cathepsin D and three dipeptidases versus leucyl-glycine, glycyl-L-leucine and glycyl-glycine) were assayed in serial, microtome prepared frozen sections (+/- 125 micrograms fresh weight) and related to histological composition (Nissl stain), dry weight, total protein, and DNA content. RNA concentrations were similarly determined, serving as approximate indices of protein synthetic potential. Cathepsin D activity and RNA concentration were, respectively, threefold and twofold greater in cortical gray than in subcortical white matter. Each dipeptidase showed somewhat higher activity in white matter than in cortex. In both tissues the order of activities were: glycyl-leucine greater than glycyl-glycine greater than leucyl-glycine dipeptidase. The results are consistent with preferential localizations of cathepsin D in cortical neurons and dipeptidases in neuroglia. None of the four enzymes showed differences in activity in comparable cortex from six patients with chronic schizophrenia.

Adult↗
PubMed1981

Jordi Folch-Pi.

Explore the source record for details and available documents.

History, 20th Century↗
PubMed1978

Activities of types A and B MAO and catechol-o-methyltransferase in blood cells and skin fibroblasts of normal and chronic schizophrenic subjects.

We assayed activities of monoamine oxidase (MAO) type B in blood platelets and type A (and B) in fibroblasts cultured from punch biopsy specimens of skin, as well as of catechol-O-methyltransferase (COMT) in erythrocytes and fibroblasts. Fibroblasts contained moderate amounts of both forms of MAO (types A and B) found in human brain and large amounts of COMT activity. Activities of both enzymes correlated poorly between fibroblasts and blood cells. Comparing carefully diagnosed chronic schizophrenics with age-matched normal young men, we found no difference in these biochemical variables, nor could we distinguish patients with paranoid symptoms. In contrast, we confirmed markedly lower MAO activities in platelet samples from chronic patients provided by colleagues at the National Institute of Mental Health. Results concerning MAO and COMT activities are now sufficiently inconsistently characteristic of schizophrenics as to question their clinical applicability and to indicate a need for further critical evaluation, with special attention to diagnosis, matching of subjects, and effects of possible spurious environmental variables.

Adolescent↗