Enhanced contractility of intraparenchymal arterioles after global cerebral ischaemia in rat - new insights into the development of delayed cerebral hypoperfusion.

AIM: Delayed cerebral hypoperfusion is a secondary complication found in the days after transient global cerebral ischaemia that worsens the ischaemic damage inflicted by the initial transient episode of global cerebral ischaemia. A recent study demonstrated increased cerebral vasoconstriction in the large arteries on the brain surface (pial arteries) after global cerebral ischaemia. However, smaller arterioles inside the brain (parenchymal arterioles) are equally important in the regulation of cerebral blood flow and yet their pathophysiology after global cerebral ischaemia is largely unknown. Therefore, we investigated whether increased contractility occurs in the intraparenchymal arterioles. METHODS: Global cerebral ischaemia was induced in male Wistar rats by bilateral common carotid occlusion for 15 min combined with hypovolaemia. Regional cerebral blood flow was determined by quantitative autoradiography. Intraparenchymal arterioles were isolated and pressurized, and concentration-response curves to endothelin-1 with and without the endothelin B receptor-selective antagonist BQ788 was generated. Endothelin B receptor expression was investigated by quantitative flow cytometry and immunohistochemistry. RESULTS: We observed increased endothelin-1-mediated contractility of parenchymal arterioles correlating with reduced cerebral blood flow of the cortex, hippocampus and caudate nucleus 48 h after global cerebral ischaemia. The increased endothelin-1-mediated contractility was abolished by BQ788, and the vascular smooth muscle cell-specific expression of endothelin B receptors was significantly increased after global cerebral ischaemia. CONCLUSION: Increased endothelin-1-mediated contractility and expression of endothelin B receptors in the intraparenchymal vasculature contributes to the development of delayed cerebral hypoperfusion after global cerebral ischaemia in combination with vascular changes of the pial vasculature.

Measurements of behavior in the naked mole-rat after intraperitoneal implantation of a radio-telemetry system.

The naked mole-rat (Heterocephalus glaber) is a unique fossorial mammal that is eusocial, object blind, and virtually poikilothermic. This animal is an ideal model to examine questions pertaining to the thermoregulatory aspects of sleep/wake cycles and other circadian events. However, the monitoring of mammalian sleep usually involves implanting permanent electrodes into the skull which are linked to a counter-weighted cable apparatus. This is not a viable option for H. glaber because of the tunneled environments and sensitive social milieu. Instead, to monitor sleep, core temperature, and activity we have utilized intraperitoneal telemetry, a technique that transmits biopotential signals by radio waves. Here we describe the surgical procedure used to implant the device, the anesthesia technique developed, and the social reintroduction method devised for this novel animal model.

Aspiration pneumonia; incidence of aspiration with endotracheal tubes.

Aspiration has been suggested as a source of pulmonary complications seen in patients with tracheal intubation. A previous study demonstrated that the high incidence of aspiration in patients with tracheostomies can be decreased by modification of the tracheostomy tube cuff design. In the present protocol, 100 patients with endotracheal tubes in place were studied to document the incidence of aspiration and to attempt to decrease the incidence by modification of cuff design. Utilizing an Evans blue dye test to detect aspiration, 27 of the 48 patients (56%) with standard low volume, high pressure cuffed tubes had positive tests. In 17 patients with modified standard cuffed tubes, the incidence of aspiration was decreased to 29% (5 patients). Aspiration was further decreased to 20% (7 patients) in the 35 patients with high volume, low pressure cuffed tubes. These results demonstrate that the incidence of aspiration in patients with endotracheal tubes can be decreased by modification of endotracheal tube cuff design.

Gratification and the failure to separate.

The authors explore the phenomenon of women who appear highly functional, but are unable to separate from their families of origin. The authors propose that families of such women often provide gratification that the women believe would not be available in marriage. Sociological variables--such as egalitarianism, inherent intimacy, time-out factors, and triangulation--and psychodynamic variables--such as failure in identification, separation-individuation, and resolution of the Oedipal situation--are discussed as contributing factors in this phenomenon.

Prospective clinical trial of antibiotics for pulmonary resections.

One hundred and seventy-one patients undergoing pulmonary resection were included in a prospective randomized clinical study evaluating the efficacy of prophylactic antibiotics. Eight-three patients randomly chosen received no parenteral antibiotics and 88 received a short course of cephalothin intravenously. Topical antibiotics were used in the pleural cavity and would of all patients. There were no statistically significant differences between the two groups in terms of days of postoperative fever, number of postoperative septic complications and length of postoperative stay. However, when postoperative infectious complications developed in the antibiotic group, they were often secondary to gram-negative organisms resistant to cephalothin.