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Biomedical subjects

J R Clarke

Publications and source records attributed to J R Clarke.

At least 127 records · Page 7Linked to original sources
PubMed1980

Optimal blood ordering for emergency department patients.

A lack of documented criteria for determining which emergency patients should have blood crossmatched for possible transfusion led us to review the records of all patients for whom blood was crossmatched in the emergency unit of our hospital in 1977. Of 378 patients who had blood crossmatched for 1,230 units, only 105 (28%) received blood transfusions (331 units total). Variables showing relationship to transfusion of blood were consolidated into four criteria: 1) shock; 2) hematocrit less than 30%; 3) observed blood loss of at least 500 ml or grossly visible gastrointestinal bleeding; and 4) emergency surgery with anticipated blood loss. Application of these criteria identified 55% of patients who did not receive transfusions and 41% of units unnecessarily crossmatched, while failing to identify only three patients received single-unit transfusions. Use of the criteria would have reduced the crossmatch/transfusion ration from 3.7:1 to 2.6:1.

Blood Banks↗
PubMed1980

Feulgen-DNA changes in the germ cells of the male vole (Microtus agrestis) during their development.

Consistent with changes in ploidy during germ cell maturation, the quantity of Feulgen DNA in round spermatids of voles is approximately a quarter of that in primary spermatocytes. The amount increases slightly in elongated spermatids, and then declines in spermatozoa from the testis, epididymis and vas deferens, below the level of round spermatids. Simultaneously nuclear area decreases so that in spermatozoa it is about one tenth that of primary spermatocytes. The rise in Feulgen DNA in elongated spermatids above the level found in round spermatids, and the decline in spermatozoa below this level, is probably caused by altered affinity of the desoxyribose for the leucofuchsin. This may be brought about by the complex physico-chemical changes occurring in chromatin and elsewhere in the nucleus and cell as they acquire their highly specialised final form.

Animals↗
PubMed1977

The effects of prednisolone in leucocyte function in man. A double blind controlled study.

The effect of prednisolone on various immunological parameters was studied in patients with ulcerative colitis in complete remission. The study was designed as a double blind trial in which patients received either prednisolone or a dummy preparation and the following observations were made:(1) The mean lymphocyte count fell from 1738 cells per mm3 to 501 cells/mm3 4 hr after prednisolone was given but by 24 hr was significantly elevated to 2399 cells/mm3; thereafter it returned to normal levels. (2) Surface marker assays of lymphocytes forming spontaneous sheep cell (E), Fc (EA), and C3 (EAC) rosettes; and cells bearing surface immunoglobulin fluctuated in approximately the same pattern as the total lymphocyte count. (3) The mitotic response to a sub-maximal stimulating dose of phytohaemagglutinin (PHA) was significantly depressed 4 hr after steroid administration but returned to normal by 24 hr. (4) Spontaneous and PHA-induced lymphocyte mediated cytotoxicity fell significantly by four hours and remained depressed to the end of steroid administration. The PHA-induced cytotoxicity was still significantly depressed 7 days after steroid administration was stopped. (5) K-cell cytotoxicity did not follow the general pattern and was only slightly reduced at four hours being lowest after 24 hr and still depressed 7 days after cessation of steroid administration. (6) The number of plasma cells in the rectal lamina propria showed no significant change after one week of steroid administration. (7) No significant changes occurred in any of the above assays, in the control group. (8) Polymorphonuclear leucocyte counts rose sharply by 4 hr in the patients receiving prednisolone. There was also a smaller but significant rise in the control group. They remained elevated for 7 days in the group receiving prednisolone, and subsequently fell to normal levels. The control group had returned to initial levels by 24 hr.

Clinical Trials as Topic↗
PubMed1976

The lung: responses to trauma, surgery, and sepsis.

The adult pulmonary distress syndrome is a disease of many etiologies and significantly contributes to the post-traumatic and postsurgical mortality and morbidity. Pulmonary insufficiency associated with shock and hemorrhage is characterized by its relatively short duration, less severe alterations of pulmonary functions, and normal pulmonary vascular resistance. The judicious use of fluids and emphasis in the early use of blood during resuscitation will minimize the magnitude of the pulmonary insult. Severe changes in oxygenation and ventilation, increases in pulmonary vascular resistance, the need for long-term respiratory assistance, and an increase in mortality and morbidity are characteristic of the adult pulmonary distress syndrome that follows severe systemic sepsis. Early aggressive pulmonary support is required in all life-threatening surgical conditions. Endotracheal intubation is preferred to tracheostomy, and the use of a volume respirator will facilitate the control of ventilation and oxygenation. Significant decreases in the functional residual capacity are responsible for refractory hypoxemia and the use of high concentrations of oxygen can be circumvented by the use of positive end expiratory pressure. PEEP is sometimes associated with a decrease in cardiac output and an increase in the pulmonary shunt and occasionally pneumothorax. Continued hemodynamic and pulmonary monitoring of patients is mandatory when using PEEP. Discontinuance of ventilatory assistance is usually possible if the pulmonary shunts are less than 25 per cent, the tidal volumes greater than 5 cc per kg, and the vital capacity at least twice the tidal volume. Recovery from pulmonary insufficiency is predicated on adequate pulmonary management, nutritional support, and the control of the underlying contributory conditions.

Abortion, Septic↗
PubMed1976

Effect of chemical sympathectomy and pinealectomy upon gonads of voles (Microtus agrestis) exposed to short photoperiod.

Day length or photoperiod is an important determinant of seasonal breeding or sexual maturation in the vole (Microtus agrestis). Exposure of voles to short (6 h) photoperiods slows gonadal development or causes active gonads to regress. Abolishing pineal activity either by chemical sympathectomy, using 6-hydroxydopamine (6-OHDA), or by surgical pinealectomy, prevents this inhibiting or regressing effect of shor photo period upon gonads. Thus, the pineal gland appears to play a part in the measurement of day length by voles and in the physiological causation of their seasonal breeding.

Animals↗
PubMed1975

Spermatogenesis in mature and regressed testes of the vole (Microtus agrestis).

Eight stages of spermatogenesis, each with a characteristic frequency and germ cell association could be recognized in the vole. There was no difference between laboratory bred and field animals in the frequency of the stages. Counts of the different types of germ cell showed that there was considerable cell loss during spermatogonial mitotic and spermatocytic meiotic divisions. Only 60% of germ cells became spermatozoa in sexually mature animals, and 19% in the regressing testes of voles exposed to short photoperiods. Animals with regressed testes probably have lowered circulating levels of gonadotrophins and testicular hormones, so that the greater germ loss suggests the importance of these hormones in the regulation of germ cell wastage. From the cell counts in mature animals, a scheme of cell divisions has been suggested by which spermatogonia produce progressively more highly differentiated germ cells while continuing to perpetuate stem cells.

Animals↗
PubMed1974

An evaluation of the rosette inhibition test in Crohn's disease.

Serial rosette inhibition tests were performed on nine patients with Crohn's disease undergoing immunosuppressive therapy in an attempt to estimate the minimum amount of drug necessary to maintain immunosuppression. The rosette inhibition titre was found to be higher in immunosuppressed patients than in normal subjects. However, there was no consistent correlation of the rosette inhibition titre with the degree of activity of the disease. The test is therefore not sufficiently discriminative to be used as a basis on which to control drug dosage.

Adolescent↗