Activation of the adenylyl cyclase/protein kinase A pathway facilitates neural release of beta-nicotinamide adenine dinucleotide in canine mesenteric artery

Using high performance liquid chromatography techniques with fluorescence detection we demonstrate that overflow of beta-nicotinamide adenine dinucleotide evoked by electrical field stimulation (16 Hz, 0.3 ms) in the canine isolated mesenteric artery is increased by the activators of adenylyl cyclase (AC) forskolin and calcitonin gene-related peptide (CGRP), by dibutyryl cAMP, and by the inhibitors of phosphodiesterases III and IV milrinone and rolipram. The enhancing effect of forskolin is abolished by the AC inhibitor MDL 12,330A and by protein kinase A (PKA) inhibitors peptide 14-22 amide and 4-cyano-3-methylisoquinoline. Therefore, activation of the AC/cAMP/PKA pathway enhances the release of beta-NAD+ from perivascular nerve terminals.     

A photorefractive study of dark focus and refraction

Photorefraction was used to estimate the position of focus in the light and in the dark of individuals with a range of refractive errors. Tests of individuals with known far points, in the light, allows empirical calibration of the photorefractive method. In the dark, position of focus was consistently about 1 D more myopic than the subject's refraction. Dark photorefraction may serve as an objective means of refraction without cycloplegia.     

Food glycemic index, as given in glycemic index tables, is a significant determinant of glycemic responses elicited by composite breakfast meals

BACKGROUND: Recent studies have concluded that the carbohydrate content and glycemic index (GI) of individual foods do not predict the glycemic and insulinemic effects of mixed meals. We hypothesized that these conclusions may be unwarranted because of methodologic considerations. OBJECTIVE: The aim was to ascertain whether the GI and carbohydrate content of individual foods influence glucose and insulin responses elicited by realistic mixed meals in normal subjects. DESIGN: With the use of a crossover design, we determined the glucose and insulin responses of 6 test meals in 16 subjects in Sydney and the glucose responses of 8 test meals in 10 subjects in Toronto and then the results were pooled. The 14 different test meals varied in energy (220-450 kcal), protein (0-18 g), fat (0-18 g), and available carbohydrate (16-79 g) content and in GI (35-100; values were rounded). RESULTS: The glucose and insulin responses of the Sydney test meals varied over a 3-fold range (P < 0.001), and the glucose responses of the Toronto test meals varied over a 2.4-fold range (P < 0.001). The glucose responses were not related to the fat or protein content of the test meal. Carbohydrate content (P = 0.002) and GI (P = 0.022) alone were related to glucose responses; together they accounted for 88% of the variation in the glycemic response (P < 0.0001). The insulin response was significantly related to the glucose response (r = 0.94, P = 0.005). CONCLUSIONS: When properly applied in realistic settings, GI is a significant determinant of the glycemic effect of mixed meals in normal subjects. For mixed meals within the broad range of nutrient composition that we tested, carbohydrate content and GI together explained approximately 90% of the variation in the mean glycemic response, with protein and fat having negligible effects.     

Traumatic events and alcohol use disorders among American Indian adolescents and young adults

This study examined the relationship between severe traumatic events and alcohol use disorders in American Indian adolescents and young adults. Interviews of 432 adolescents and young adults who were enrolled tribal members living on or near two closely related American Indian reservations were used. Results indicated that severe trauma increased the odds of alcohol use disorders (p <.001), with the number of traumas having a dose-dependent effect. The authors conclude that trauma is associated with alcohol use disorders in this population. This study's findings yield important insights into the risks in American Indian adolescents and young adults that may result from early trauma, as well as implications for the timing and possible settings for intervention.     

Prenatal diagnosis of fetal arrhythmias

Life-threatening fetal arrhythmias are rare and warrant sophisticated specialty prenatal care, often provided by maternal-fetal medicine obstetricians, and pediatric and adult cardiologists. This medical field is in quick transition, and new methods of diagnosis and treatment of the fetus with arrhythmias are emerging. In this article, the mechanisms of arrhythmias are presented in light of recent progress in the new field of fetal electrophysiology. Treatments are reviewed with recommendations based on the small number of series of fetal tachycardia and fetal atrioventricular (AV) block drug treatment strategies published to date. Finally, a summary of areas of potential future research is provided.     

An improved autoradiographic coating technique for neurohistopathological stains and electron microscopy

We describe modifications and improvements to our first report of a new nuclear emulsion coating technique for both light and electron microscopic autoradiography. Although this technique was originally designed to facilitate electron microscopic autoradiography, the methodology also allows pre-staining of plastic-embedded tissue sections prior to coating the slides with nuclear emulsion for light microscopic autoradiography. We now demonstrate that paraffin sections can be autoradiographically processed after being subjected to a combination of immunocytochemical reactions and special neuroanatomical stains. Parlodion film has been found to be more resistant to temperature changes and less prone to contamination than Formvar film. The shape of the double adhesive tape is an important aspect of the electron microscopic technique; it has been modified to minimize contamination and facilitate the removal of the grids from the glass slide. These technical adjustments facilitate the application of the nuclear emulsion and increase radionuclide specificity, thus expanding the investigative horizons of light and electron microscopic autoradiography.