The effects of calcium and magnesium on inhibitory junctional transmission in smooth muscle of guinea pig small intestine

Summary The membrane potential of smooth muscle cells in the circular layer of the guinea pig ileum was recorded using intracellular electrodes. Transmural stimulation, in the presence of atropine, caused a transient hyperpolarization, an inhibitory junction potential (IJP). IJP's are thought to result from the action of transmitter released from intramural inhibitory nerves. It has been reported that, in the guinea pig jejunum, the amplitude of the IJP resulting from field stimulation is not altered by changes in the calcium and magnesium ion concentration in the bathing solution. Experiments reported here have shown that the IJP amplitude decreased markedly on reducing the calcium ion concentration and or increasing the magnesium ion concentration. Indirect evidence is presented suggesting that the decrease in amplitude of the IJP is due to a decrease in the amount of transmitter released.     

Death and the health professional: organization and defense in health care

Organizational and technological developments within the health care system have helped consolidate a power structure that dehumanizes clients and fosters defensive-ness in professionals. Frequent exposure to death renders health professionals vulnerable to severe anxiety, which they may try to avoid through death denial, leaving them psychologically unable to support dying clients. Professional education, attitudes equating death with professional failure, organizational coping strategies among nurses, and staff burnout interact to perpetuate this atmosphere. As a model for learning, this article analyzes a pediatric case study to illuminate the manifestations of professional defensiveness. Finally, I consider three specific problem-solving strategies: improving morale, opening communication, and expanding professional education to include death studies and psychological study of the health organization. Bringing humanity back into the health care environment is possible to the extent that both the organization and its members are responsive and open to change.     

Methadone: old problems for new programmes

The present paper is concerned with factors which compromise the effective delivery of programmes incorporating methadone. Current clinical practices and programme characteristics are reviewed and policy issues regarding the role of methadone are considered, especially within the context of containing the spread of HIV infection. These issues are discussed in relation to empirical outcome studies, local prescribing trends and clinical case material. The authors conclude that there is an urgent need for: (1) an evaluation of the outcome of private practitioner methadone dispensation versus comprehensive agency-based therapy; (2) the accreditation of staff in all programmes incorporating methadone; and (3) the development of monitoring mechanisms, including on-site clinical audits of programmes.     

Reconstruction of male external genitalia with elephantiasis

The surgical rehabilitation of a patient with severely deformed and functionally disabled genitalia due to long-standing lymphedema and infection is described and illustrated. The term "elephantiasis" has been applied to such gross lesions. Appropriate surgery to the penis, scrotum, and perineum has yielded a gratifying result. The principles and techniques of the surgical approach in such an undertaking are presented and discussed.     

The vasa vasorum and angioplasty

Interruption of flow in the vasa vasorum may lead to medial necrosis and aneurysm formation. The purpose of this study was to determine whether angioplasty produces significant alterations in the morphology or blood flow of the vasa vasorum of the dilated artery. The morphology of the canine vasa vasorum was studied before and after angioplasty; in a separate experiment vessel wall blood flow (VWBF) in canine carotid arteries was measured after angioplasty to determine whether physiologic regulation of the blood flow was disrupted by arterial dilation. No morphologic changes could be demonstrated in the vasa vasorum of the dilated artery; however, VWBF was increased by 1194 +/- 215% (mean +/- standard error, p less than 0.01) between 90 and 120 minutes after angioplasty. VWBF in the adjacent nondilated arterial segment was also increased (720 +/- 177% between 10-30 minutes, p less than 0.01) but returned toward normal after 60 minutes. Adenosine caused a "paradoxical" decrease in VWBF (p less than 0.05) of the dilated arterial segment while causing increased VWBF (p less than 0.05) in the thoracic aorta. Angioplasty appears to produce persistent hyperemia in the dilated arterial wall. A paradoxical response to adenosine suggests that vasa vasorum in the dilated arterial segment are maximally vasodilated. This may be due to mechanical disruption of vasomotor tone or to release of vasoactive substances.     

Aberrant crypt focus promotion and glucose intolerance: correlation in the rat across diets differing in fat, n-3 fatty acids and energy

McKeown-Eyssen (Cancer Epidemiol. Biomarkers Prevent., 3, 687-695, 1994) and Giovannucci (Cancer Causes Control, 6, 164-179, 1995), noting the striking similarity in lifestyle risk factors for colorectal cancer and insulin resistance, proposed that the hyperinsulinemia, glycemia and hypertriglyceridemia associated with insulin resistance promotes colon cancer. To compare the effect of diet on colon cancer promotion and insulin resistance in the F344 rat, we assessed the effect of fat, n-3 fatty acids and energy in pairwise comparisons on average size of aberrant crypt foci (ACF) and on glucose intolerance in the same animals in a single experiment. Diets high in fat and energy increased and diets with increased n-3 fatty acids and calorie restriction decreased both ACF growth and glucose intolerance compared with control diets. The measures of promotion of colon cancer and insulin resistance were strongly correlated (n = 98, r = 0.67, P < 0.001). In addition, both were highly correlated with daily energy intake (r = 0.62 and 0.66) and were also correlated with basal (post-prandial) insulin, glucose and triglycerides (r = 0.31-0.53, P < 0.01). We concluded that ACF growth and glucose intolerance are correlated for a wide range of diets and that increased circulating energy (glucose and triglycerides) may lead to both colon cancer promotion and insulin resistance.