Organization of neural inputs to the suprachiasmatic nucleus in the rat

The circadian timing of the suprachiasmatic nucleus (SCN) is modulated by its neural inputs. In the present study, we examine the organization of the neural inputs to the rat SCN using both retrograde and anterograde tracing methods. After Fluoro-Gold injections into the SCN, retrogradely labeled neurons are present in a number of brain areas, including the infralimbic cortex, the lateral septum, the medial preoptic area, the subfornical organ, the paraventricular thalamus, the subparaventricular zone, the ventromedial hypothalamic nucleus, the posterior hypothalamic area, the intergeniculate leaflet, the olivary pretectal nucleus, the ventral subiculum, and the median raphe nuclei. In the anterograde tracing experiments, we observe three patterns of afferent termination within the SCN that correspond to the photic/raphe, limbic/hypothalamic, and thalamic inputs. The median raphe projection to the SCN terminates densely within the ventral subdivision and sparsely within the dorsal subdivision. Similarly, areas that receive photic input, such as the retina, the intergeniculate leaflet, and the pretectal area, densely innervate the ventral SCN but provide only minor innervation of the dorsal SCN. A complementary pattern of axonal labeling, with labeled fibers concentrated in the dorsal SCN, is observed after anterograde tracer injections into the hypothalamus and into limbic areas, such as the ventral subiculum and infralimbic cortex. A third, less common pattern of labeling, exemplified by the paraventricular thalamic afferents, consists of diffuse axonal labeling throughout the SCN. Our results show that the SCN afferent connections are topographically organized. These hodological differences may reflect a functional heterogeneity within the SCN.     

Growth and coarsening of g. p. Zones in Al- Zn alloys

The structural changes during the precipitation of G. P. zones in Al-Zn binary alloys have been investigated by means of anin situ small-angle scattering technique using synchrotron radiation. Defining a specific time, normalized by the half-completion time, the time-dependent evolution of the precipitation process can be divided into three periods, independent of alloy composition and quench-ing conditions. The structural and kinetic features of the first two periods have been analyzed in detail. The first stage represents a growing process of clusters with diffuse interface into the well-defined G. P. zones. The average size of these clusters increases, and the density decreases. The second stage corresponds to the Ostwald ripening process. This mechanism is described by utilizing a modified Lifshitz-Slyozov-Wagner theory.     

A computer simulation on tensile strength of surface-Damaged fibers

The strength of surface-damaged fibers was studied by means of a computer simulation experiment based on the Monte-Carlo method using a simple model which assumes that the surface flaws can be regarded as mode I notches on fiber surfaces, the strength of undamaged fibers obeys the Weibull distribution function, and the largest flaw determines the strength of damaged fibers. Normal and exponential distribution functions were taken as the flaw size distribution function. By employing the present simulation method, the effects of average flaw size, coefficient of variation of flaw size, density of flaws, and gage length on average strength and its coefficient of variation were studied. It was found that the surface-damaged fibers can retain their full strength only when the average flaw size is small, the coefficient of variation of flaw size is small, density of flaw size is low, and gage length is short. Otherwise the average strength of damaged fibers was reduced seriously. It was emphasized that the scatter of size of flaws and density of flaws strongly affect the strength of fibers as well as flaw size and gage length.     

Influence of third elements on growth of Nb3Sn compounds and on global pinning force

The crystal growth of Nb₃Sn by the bronze method has been investigated by using diffusion couples consisting of niobium and bronze with the addition of third elements. When the specimens were annealed at temperatures between 973 and 1073 K, the time-dependence of layer thickness was represented approximately by the function ofd=kt ^m . The time exponent changed from 1/3 to unity depending on the annealing condition as well as on the nature of the third element. By the addition of titanium, hafnium, zirconium, indium and galium to the bronze, the growth rate of the compound layer increases. Faster layer growth corresponds to a larger time exponent. The following three processes are suggested to be important for controlling layer growth: diffusivity of tin atoms through grain boundaries in the compound layer, diffusivity of tin atoms through the matrix of the compound, and the rate of the chemical reaction to form the compound. Essentially these combined processes control the overall rate of layer growth. The grain size is found to be the most effective structural parameter to affect directly the maximum global pinning force. The critical current at a magnetic field of 5T can be scaled by both the layer thickness and the inverse grain size.     

Application of preembedding immunohistochemistry in the study of adenohypophysial plurihormonality

An immunoelectron microscopy preembedding technique has been utilized as a method which enables the observation of various bioactive substances in various intracellular organelles. In this review article, the observations made by preembedding immunoelectron microscopy describe plurihormonal pituitary cells emphasizing subcellular localization of hormones and their alterations.     

Diagnostic and prognostic role of basic fibroblast growth factor in Wilms' tumor patients

Basic fibroblast growth factor (bFGF) is a potent angiogenic peptide implicated in the growth and metastasis of solid tumors. Elevated concentrations of bFGF have been found in the urine of patients with bladder, prostate, and renal tumors. Furthermore, urinary bFGF levels have been shown to correlate with extent of disease. In order to test the utility of urinary bFGF as a Wilms' tumor marker, we measured bFGF levels in preoperative and postoperative urine samples from 97 patients with Wilms' tumor. Preoperative urine samples (n = 97), early postoperative samples obtained from 1 to 3 weeks after surgery (n = 43), and late postoperative samples obtained from 1 to 6 months after surgery (n = 66) were collected from Wilms' tumor patients at 30 institutions between 1989 and 1993. Urine samples from age-matched controls (n = 17) were also obtained. The bFGF levels were determined in duplicate by a competitive sandwich ELISA capable of measuring bFGF at the pg/ml level. Samples were normalized for creatinine content. Urinary bFGF was elevated in 42% of preoperative samples when compared to controls (>90th percentile of normal). Patients with stage III, IV, and V disease had significantly higher preoperative levels of urinary bFGF when compared to patients with stage I and II disease (P < 0.01). Patients with relapse or persistent disease had significantly elevated late postoperative bFGF levels when compared to disease-free patients and controls (P < 0.05). Thus, in patients with Wilms' tumor, elevated preoperative urinary bFGF levels raise the suspicion of aggressive disease while elevated postoperative levels may indicate recurrence or persistence of disease. These data suggest that bFGF is a biological marker for Wilms' tumor and may have a role in the evaluation of patients with this disease.     

The significance of electrocardiography in locating original sites of ventricular tachycardia

The sites of origin of ventricular tachycardia (VT) in 12 patients were located by ECG during the episode and further confirmed by catheter mapping. The results showed that there were 14 sites of origin of VT in the 12 patients from ECG in which 1 site was incompletely mapped by catheter and 12 of the other 13 original sites were confirmed by the catheter endocardial or epicardial mapping. Of the 12 original sites of VT, the locating of 11 ones were completely consistent with those from ECG, which was 84.6% of the 13 original sites. Moreover, 8 of the 12 patients had been successfully treated by catheter direct or radiofrequency current ablation and 1 of the 12 by successful surgical operation. Thus, the original sites of VT located by ECG was reliable and could shorten the time of catheter mapping during non-pharmacological therapy of VT.