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Biomedical subjects

C Marshall

Publications and source records attributed to C Marshall.

At least 127 records · Page 7Linked to original sources
PubMed1983

Influence of perfusate PO2 on hypoxic pulmonary vasoconstriction in rats.

The purpose of these studies was to evaluate the influence of perfusate oxygen tension on hypoxic pulmonary vasoconstriction and to identify the site at which both alveolar and perfusate gas tensions stimulate hypoxic pulmonary vasoconstriction. Lungs from adult rats were ventilated and perfused in vitro at constant temperature, PCO2, and pH, with a perfusion circuit incorporating a membrane oxygenator that allowed independent control of the alveolar and perfusate gas tensions. Blood flow to the lung was constant (0.06 ml per g body weight per min), and pulmonary vascular resistance was therefore proportional to pulmonary artery pressure. In study 1, the pulmonary artery pressor response to zero or 22 mm Hg alveolar oxygen was measured when the perfusate oxygen tensions were approximately 8, 26, 41, 64, or 128 mm Hg. The pressor response as a percent of the maximum pressure change was progressively reduced as perfusate oxygen tension increased. For alveolar oxygen tension of zero; the pressor response = 128 -39 (Log PPO2) and r = 0.8 (P less than 0.01), the effect of perfusate gas tension on the response to alveolar gas tension of 22 mm Hg was similar. These results demonstrate that the stimulus for hypoxic pulmonary vasoconstriction is a function of both alveolar and perfusate oxygen tension. In study 2, the response to alveolar oxygen tension of 42 mm Hg was measured with mean perfusate oxygen tensions of 130, 52, and 17 mm Hg. In six animals with forward perfusion, the responses decreased with increasing perfusate oxygen tension, as in study 1. In another six animals, with retrograde perfusion, the responses to alveolar hypoxia were not altered when perfusate oxygen tension was increased. These results demonstrate that the sensor region for hypoxic pulmonary vasoconstriction is precapillary. These studies confirm and extend previous hypotheses that alveolar and perfusate oxygen tensions together, determine the PO2 at a precapillary site to stimulate hypoxic pulmonary vasoconstriction.

Animals↗
PubMed1982

Influence of ventilation on response to fluid load in dogs: body water and albumin distribution.

Beagle dogs were sedated with intravenous pentobarbital ventilated for 46 h with either spontaneous ventilation (SV), controlled ventilation (CV), or controlled ventilation with 10 cmH2O end-expiratory pressure (CV + PEEP). Throughout the study period saline (0.45 per cent with added KCl) was infused at 120 ml/h. The influence of ventilatory mode on the accumulation and organ distribution of body water during continuous fluid loading was determined. Five animals were studied with each ventilatory mode. In all groups body weight increased, but with SV weight increase began only after 28 h and increased by 7.2 per cent of body weight by 46 h. With CV the weight increase was continuous and was 9.2 per cent of initial body weight at 46 h. With CV + PEEP the increase was earlier and greater reaching 22 per cent by 46 h. Radioisotopic analysis of total body water, extracellular water, and plasma and erythrocyte water demonstrated that the body weight increase was due to water retention principally in the extracellular compartment. Postmortem analysis of the major body organs for water and albumin distribution demonstrated increased water in the muscle and subcutaneous tissue of the CV + PEEP group that accounted for the total difference in water retention compared to the SV or CV animals. Organ extravascular albumin content varied relatively little between ventilatory modes. Ventilation with increased mean pressure was accompanied by marked and prolonged fluid retention. In these otherwise healthy dogs the water accumulation confined to sites that appeared unlikely to interfere with organ function.

Albumins↗
PubMed1981

Hypoxic pulmonary vasoconstriction in dogs: effects of lung segment size and oxygen tension.

Six pentobarbital-anesthetized dogs were prepared with endobronchial tubes and electromagnetic flow probes. The effects of changing inspired oxygen concentrations (FIO2 = 1, 0.21, 0.15, 0.1, 0.075, 0.05, and 0) were tested on test segments of different size corresponding to left lower lobe, left upper lobe-lingula, left lung, right lung, right lung plus left lower lobe, right lung plus left upper lobe-lingula, and whole lung. In each test the rest of the lung received oxygen. Hypoxic pulmonary vasoconstriction is demonstrated by both diversion of blood flow away from hypoxic test segments and by increased perfusion pressure. Flow diversion (FD%) decreases with the size of the hypoxic test segment (%QSN) from a maximum of 75% for very small segments to zero when the whole lung is hypoxic. FD% increases linearly as alveolar oxygen tension (PAO2) of the test segment is decreased in the range of 130--28 Torr. When mixed venous oxygen tension (PVO2) is less than 45 Torr FD% is reduced. These relationships are described by FD% = [74.99 - 0.0778 (%QSN) - 0.00661 (%QSN)2] [1.268 - 0.0096 (PAO2)] [0.47 + 0.012 (PVO2)], with r = 0.92 and standard error for prediction of 8.4%. Pulmonary perfusion pressure changes (PPH/PPN) increase with the size of the hypoxic test segments from 0 with very small segments to approximately 2.2 for the hypoxic whole lung. For all test segments PPH/PPN increases linearly with PAO2. These relationships are described by PPH/PPN = 1 + [0.0043 (%QSN) + 0.000072 (%QSN)2] [1.234 - 0.0096 (PAO2)], with r = 0.91 and standard error for prediction of 0.3 units. Responses to hypoxic pulmonary vasoconstriction in dogs are therefore shown to be predictable and continuous, and the physiological basis for action of each of the variables is discussed.

Animals↗
PubMed1981

Brucellosis in free-living African buffalo (Syncerus caffer): a serological survey.

The rose bengal and complement fixation tests were successfully applied to buffalo (Syncerus caffer) sera. An overall occurrence of 23% positive reactors was obtained, but Brucella infection does not appear to act as an effective culling agent in buffalo. Any eradication programme must take free-living buffalo into account as a possible source of re-infection for cattle.

Agglutination Tests↗
PubMed1979

Radiation and microwave therapy in the treatment of advanced cancer.

Seventy-two patients with advanced cancer were treated with combinations of heat and radiation in two groups: (a) heat + radiation, and (b) radiation + heat. Of those treated with heat prior to radiation therapy, 32/60 (53%) experienced complete remission of symptoms. In the group exposed to heat after radiotherapy, 11/12 patients (92%) achieved complete remission. The authors present two cases and a review of the literature.

Aged↗
PubMed1978

Telemedicine in pediatric primary care. Favorable experience in nurse-staffed inner-city clinic.

Off-site pediatric consultation via bidirectional cable television (TV) was instituted to provide backup for nurse practitioners treating sick and well children in a small primary-care clinic. During a year of study of the system, there were 2,161 clinic visits and 285 TV consultations. When both TV and telephone consultation were available, TV was used for 10.8% of the visits, and telephone was used for 9.6% of visits. Staff reactions, though initially skeptical, were ultimately favorable. The system allowed pediatric nurse practitioners to function without on-site physician coverage 40% of the time. The main disadvantages were technical. Further work is needed to assess the reliability and validity of TV consultation and its acceptability in other settings.

Attitude of Health Personnel↗
PubMed1978

Child health.

Explore the source record for details and available documents.

Child↗
PubMed1977

Preliminary clinical results of combined 433 Megahertz microwave therapy and radiation therapy on patients with advanced cancer.

Seventy patients with far-advanced histologically proven malignancies were treated with a combination of microwave irradiation (433.92 MHz) and ionizing radiation. Of the twenty-one patients who completed the planned course of treatments and are eligible for a minimum of nine-month follow-up, 90% experienced complete relief of symptoms and 10% received partial relief of symptoms. Complete regression of all localized tumor occurred in sixteen of the twenty patients (80%), and nine of the complete responders remain free of disease from nine to fourteen months. It was the opinion of the clinicians involved in this study that the heat administered by the microwave unit potentiated the effects of ionizing radiation over those which would have been seen if radiation were used alone. In view of the fact that all patients in this study had cancers which were previously considered to be refractory to further medical treatment, the marked relief of symptoms and tumor response to combined therapy were encouraging. This preliminary study confirms the impression that the effects of radiation are enhanced by heat and forms the basis for a randomized series involving far-advanced but previously untreated head and neck and gynecological malignancies.

Adolescent↗
PubMed1977

Control of extracellular slime accumulation in monokaryons and resultant dikaryons of Schizophyllum commune.

Extracellular slime accumulation, as alcohol-precipitable material was measured after eight days of growth in glucose-asparagine-salts broth in twenty-two different monokaryons and six resultant dikaryons of Schizophyllum commune. The nutritional control of slime accumulation was also examined in monokaryotic mycelium. Slime occurred after growth in sucrose, glucose, fructose and xylose, with glycerol best. Low inorganic phosphates limited both slime and mycelial growth while limiting MgSO4 decreased growth and enhanced slime. In glucose-asparagine broth, various monokaryons differed widely in slime accumulation, ranging from none (e.g., strain 19) to nearly 800 mg per 100 ml filtrate (strain 1) after eight days growth, followed by a marked decline in slime (eleven days to twenty-one days). Resultant dikaryons all showed less slime accumulation, even when established from two high slime-accumulating monokaryons. In contrast, conditions which arrested dikaryotic fruit-body morphogenesis led to increased slime accumulation.

Agaricales↗
PubMed1976

The use 0f two-way TV in bringing mental health services to the inner city.

The authors describe a cable TV link between a medical school and a child health station in East Harlem. Nurse associates and community health workers trained through television conferences with a child psychiatrist have the primary responsibility for patient care at the clinic. Patients and their mothers are evaluated by the child psychiatrist in TV consultations at which nurse associates, health workers, medical students, and child psychiatric fellows are present. Patients and mothers respond positively to the system, and a high percentage of the psychiatrist's treatment recommendations are accepted. The authors suggest that such TV links can increase mental health services to underserved inner-city children.

Allied Health Personnel↗
PubMed1975

Isolated seizures: an EEG and clinical assessment.

A study has been made of 39 patients with isolated fits presenting to an EEG department. Patients were excluded when there was a doubtful history, alcoholism, or drug abuse. The 39 patients were compared with a control group of patients with epilepsy matched for age and sex. No basic difference was found between the two groups. In particular the EEG examination showed similar changes. In conclusion, patients with isolated fits should be assessed in the same way as those with established epilepsy, while recognizing that in the majority of instances no serious underlying cause will be found.

Adolescent↗