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Biomedical subjects

R H Shepard

Publications and source records attributed to R H Shepard.

14 recordsLinked to original sources
PubMed1979

DLO2 in excised lungs perfused with blood containing sodium dithionite (Na2S2O4).

If the excised lung is perfused with blood containing the chemical sodium dithionite (DDT), the PO2 of pulmonary capillary blood is everywhere zero and the membrane diffusing capacity for O2 (DmO2) can be measured by a standard rebreathing technique. The reaction rate of DDT with O2 is not rate limiting in the DmO2. In 15--25 kg dogs anesthetized with pentobarbital sodium (30 mg/kg, iv), left lower lobe was excised, suspended horizontally and perfused with autologous blood at 25--27 degrees C. DDT was added to the blood and the rebreathing alveolar disappearance curves for O2 were measured. The DmO2 ranged from 6 to 43 (ml/min.Torr, STPD) at lung volumes of 240--780 ml (FRC at 6 cmH2O end-expiratory pressure). Lung weight, pulmonary artery pressure, and the DmO2 were stable in the presence of DDT. Histopathology indicates that dithionite in the concentrations used does not harm the lung. Effects of inequalities in the distributions of ventilation, volume, and diffusing capacity were examined in a two-compartment model and compared with the experimental findings.

Animals↗
PubMed1979

Spinal cord injury in the monkey: rate of cord cooling and temperature gradient during local hypothermia.

We have investigated the effectiveness of surface cord cooling in reducing spinal cord temperature with respect to the rate of cooling and the temperature gradient within the spinal cord parenchyma. Another question of some practical importance if spinal cooling is to be used clinically is that of the temperature within the spinal cord as a function of the dura being intact or open. In five monkeys, a laminectomy was carried out at T-10 and an impact injury of 350 g-cm force was applied to the spinal cord with the dura intact. Hypothermic perfusion with Elliott's B solution (artificial cerebrospinal fluid) was started, and we measured temperatures in the spinal cord with a thermistor probe mounted on a stereotactic drive. A series of measurements were made with the dura intact and the measurements were then repeated with the dura open. For comparison, we also recorded temperatures in one animal that had not been cord-injured. The rate of cord cooling was rapid during the first 3 minutes of hypothermic perfusion, after which there was a slight further reduction in cord temperature; a low level plateau of 6.7 degrees C was reached within 21 minutes after the start of cooling. The temperature gradient at varying depths of the spinal cord was approximately 6 degrees C (3.8 degrees C at the posterior surface to 10.1 degrees C in the deepest portion of the spinal cord), representing a temperature gradient of 1.3 degrees C/mm of cord tissue. Transmission of the cooling effect from perfusate to the spinal cord was not appreciably affected by the dura being intact or open. (Neurosurgery, 5: 583--587, 1979).

Animals↗
PubMed1978

Relationship of necrosis and tumor border to lymph node metastases and 10-year survival in carcinoma of the breast.

The pathologic findings of 330 patients with invasive carcinoma of the breast who were followed for 10 years after radical mastectomy was reviewed. The presence or absence of necrosis and the character of the border of the tumor were two factors which were observable in all cases. Necrosis in the carcinoma was associated with a higher mortality rate, a higher incidence of axillary node metastases, and a higher mortality rate in patients with axillary node metastases than were primary carcinomas without necrosis. Tumors with necrosis and a root border showed significantly more aggressive behavior than did those tumors with a rounded border and no necrosis.

Breast Neoplasms↗
PubMed1977

The characteristics and mortality of outpatient-acquired pneumonia.

One-hundred fifty-four cases of pneumonia occurring over a 6-month period were analyzed. Population characteristics, admission diagnoses, causative pathogens, frequency of associated illnesses, antibiotic usage and mortality were evaluated. Despite population characteristics known to predispose to a poor clinical outcome, the mortality was low, probably because of rapid institution of a single, appropriate antibiotic.

Adult↗
PubMed1975

Outcome of head trauma: age and post-traumatic seizures.

A series of 307 head-injured children (0-14 yr) was followed from the acute phase for up to six years with a separate group of 220 non-injured siblings as control. The neurological, EEG, psychometric and psychiatric findings were analysed. Here we discuss the influence of age at time of injury with respect to post traumatic seizures. Overall incidence of early seizures (during first week) was 15% and of late seizures (one week to six years) was 5%. Youngest children (0-2 yr), however, had a low frequency (3%) of early seizures, but 11% frequency of late seizures. The frequency of early seizures was higher and frequency of the late seizures was lower in children than in adults with either closed or penetrating injuries. Comparison of these data with those of other investigators suggested that the overall incidence of early seizures in children 2-14 yr of age is higher than in adults, whereas the late occurrence of seizures appears to be lower than that in adults. The pattern, however, in the youngest children 0-2 yr of age resembles that of adults (particularly adults with penetrating injuries).

Adolescent↗