Branching patterns of the subclavian arteries in German Shepherd dogs.

This study is the first report of the branching pattern of the four major branches of the subclavian artery in German Shepherd dogs. A total 116 subclavian artery casts made of silicon under mean arterial pressure were analysed. The casts were classified according to their branching order and the pattern of the first two branches of the vertebral artery and costocervical trunk. The three subtypes of each major type were based on the branching order or level of the next two branches (the superficial cervical artery and internal thoracic artery). Eleven of 12 possible subtypes were found in the samples. The number of dogs having the same branching subtype of the left and right subclavian arteries was not greater than those having a different subtype. The distance between the first and last branches of the subclavian artery was always longer on the left side than on the right. However, gender-based differences were identified neither in the subtype patterns nor in the distance between the branches. These results suggest a variable branching of the subclavian arteries with frequent differences of the branching pattern on the left and right sides in German Shepherds.

Recent advances in the study of structural materials compatibility with hydrogen.

Hydrogen is a ubiquitous element that enters materials from many different sources. It almost always has a deleterious effect on mechanical properties. In non-hydride-forming systems, research to date has identified hydrogen-enhanced localized plasticity and hydrogen-induced decohesion as two viable mechanisms for embrittlement. However, a fracture prediction methodology that associates macroscopic parameters with the degradation mechanisms at the microscale has not been established, as of yet. In this article, we report recent work on modeling and simulation of hydrogen-induced crack initiation and growth. Our goal is to develop methodologies to relate characteristics of the degradation mechanisms from microscopic observations and first-principles calculations with macroscopic indices of embrittlement. The approach we use involves finite element analysis of the coupled hydrogen transport problem with hydrogen-assisted elastoplastic deformation, thermodynamic theories of decohesion, and ab initio density functional theory calculations of the hydrogen effect on grain boundaries.

Morphometric studies on the testis of Korean ring-necked pheasant (Phasianus colchicus karpowi) during the breeding and non-breeding seasons.

The purpose of this study was to obtain detailed quantitative information on all cell types in the testis interstitium of Korean ring-necked pheasants and to combine these data with changes in the steroidogenic function of the testis during the breeding and non-breeding seasons. For animals collected during the breeding season, their testis weights, sperm production, serum testosterone levels and leuteinizing hormone (LH)-stimulated testosterone secretion were significantly (p < 0.01) increased compared to the non-breeding season. Testes of the pheasants during the non-breeding season displayed a 98% reduction in testis volume that was associated with a decrease in the absolute volume of seminiferous tubules (98% reduction), tubular lumen (100%), interstitium (90%), blood vessels (84%), lymphatic spaces (97%), Leydig cells (79%), mesenchymal cells (51%) and myoid cells (61%) compared to the breeding season. The numbers of Leydig cells, mesenchymal cells and myoid cells per testis in the breeding season were much higher than in the non-breeding season. Although the mean volume of a Leydig cell was 74% lower in the non-breeding season, the mean volumes of myoid and mesenchymal cells remained unchanged. These results demonstrate that there are striking differences in the testicular structure of the Korean ring-necked pheasant during the breeding and non-breeding seasons. Every structural parameter of the Leydig cell was positively correlated with both testosterone serum levels and LH-stimulated testosterone secretion. The correlation of changes in hormonal status with the morphometric alterations of Leydig cells suggests that the Korean-ring necked pheasant may be used as a model to study structure-function relationships in the avian testis.

Effect of low-dose prophylactic dopamine on high-dose cisplatin-induced electrolyte wasting, ototoxicity, and epidermal growth factor excretion: a randomized, placebo-controlled, double-blind trial.

PURPOSE: To evaluate the protective effect of low-dose dopamine given as continuous infusion in patients who undergo chemotherapy with the nephrotoxin cisplatin. PATIENTS AND METHODS: Forty-two patients who received high-dose cisplatin-containing chemotherapy entered a prospective, randomized, double-blind, placebo-controlled trial. Twenty-one patients received dopamine, and 21 received placebo. Patients were to receive either infusional dopamine 2 micrograms/kg/min over 48 hours or placebo. Cisplatin 125 mg/m2 was administered 12 hours after initiating dopamine (group D) or placebo (group P). This schedule was repeated twice, 1 week apart. Measurements of serum creatinine, urinary electrolytes and creatinine, urinary excretion of epidermal growth factor (EGF), ototoxicity, parameters of hematopoietic recovery, and duration of hospitalization were analyzed. RESULTS: We observed an increase in serum creatinine level to a peak of 1.9 mg/dL (range, 0.8 to 7.8) in the dopamine group, in comparison to 1.4 mg/dL (range, 0.9 to 3.3) in the placebo group (P = .04). Urinary magnesium excretion increased and EGF excretion decreased in both groups. Urinary sodium, chloride, and potassium excretion were increased in both groups, but more so in the placebo group. Dopamine had no measurable effect on hearing loss, duration of hospitalization, or hematopoietic recovery. CONCLUSION: The use of prophylactic dopamine increased peak serum creatinine levels relative to placebo and failed to prevent cisplatin-induced renal toxicity or ototoxicity. Determination of whether dopamine could reverse chemotherapy-induced renal damage would require a randomized prospective trial.