Superconductivity induced by longitudinal ferromagnetic fluctuations in UCoGe.

From detailed angle-resolved NMR and Meissner measurements on a ferromagnetic (FM) superconductor UCoGe (T(Curie)∼2.5 K and T(SC)∼0.6 K), we show that superconductivity in UCoGe is tightly coupled with longitudinal FM spin fluctuations along the c axis. We found that magnetic fields along the c axis (H∥c) strongly suppress the FM fluctuations and that the superconductivity is observed in the limited magnetic-field region where the longitudinal FM spin fluctuations are active. These results, combined with model calculations, strongly suggest that the longitudinal FM spin fluctuations tuned by H∥c induce the unique spin-triplet superconductivity in UCoGe. This is the first clear example that FM fluctuations are intimately related with superconductivity.

Anisotropic magnetic fluctuations in the ferromagnetic superconductor UCoGe studied by direction-dependent 59Co NMR measurements.

We have carried out direction-dependent 59Co NMR experiments on a single crystal sample of the ferromagnetic superconductor UCoGe in order to study the magnetic properties in the normal state. The Knight-shift and nuclear spin-lattice relaxation rate measurements provide microscopic evidence that both static and dynamic susceptibilities are ferromagnetic with strong Ising anisotropy. We discuss that superconductivity induced by these magnetic fluctuations prefers spin-triplet pairing state.

Identification of a novel Sry-related gene and its germ cell-specific expression.

Sox family proteins are characterized by a unique DNA-binding domain, a HMG box which shows at least 50% sequence similarity with mouse Sry, the sex-determining factor. At present almost 30 Sox genes have been identified. Members of this family have been shown to be conserved during evolution and to play key roles during animal development. Some are involved in human diseases, including sex reversal. Here we report the isolation of a novel member of the Sox gene family, Sox30, which may constitute a distinct subgroup of this family. Using a bacterially expressed DNA-binding domain of Sox30, we show that it is able to specifically recognize the ACAAT motif. Furthermore, Sox30 is capable of activating transcription from a synthetic promoter containing the ACAAT motif. The specific expression of Sox30 in normal testes, but not in maturing germ cell-deficient testes, suggests the involvement of Sox30 in differentiation of male germ cells. Mapping analyses revealed that the Sox30 gene is located on human chromosome 5 (5q33) and on mouse chromosome 11.

Effects of thiopental on regional blood flows in the rat.

BACKGROUND: The goal of this investigation was to characterize the effects of thiopental on cardia output and regional blood flows in the rat. Blood flows influence thiopental pharmacokinetics. Acquisition of these data may ultimately permit evaluation of the contribution of thiopental-induced alterations in regional blood flows to the disposition and hypnotic effect of this drug. METHODS: Chronically instrumented unrestrained Wistar rats (n=20) aged 3-4 months received either a dose of thiopental sufficient to induce a brief period of unconsciousness (20 mg.kg(-1)) or a larger dose achieving electroencephalographic burst suppression (45 mg.kg(-1)). Cardiac output and blood flows to 14 tissues were determined at 4 times in each rat for a period of 420 min using injections of radioactive microspheres (expressed as mean +/- SD). Mean arterial pressure, heart rate, and blood gas tensions were determined at all measurement times. Arterial plasma concentrations were sampled at postinfusion times. RESULTS: No important changes in systemic cardiovascular measurements were detected after the smaller dose of thiopental. One minute after the larger dose, cardiac output decreased from baseline (123 +/- 14 to 84 +/- ml.min (-1), P< 0.01), flow to muscle and fat decreased, and muscle and fat resistance increased. At 5 min, compared to baseline, no difference in cardiac output was detected (123 +/- vs. 119 +/- ml.min (-1)), intestinal flows increased and intestinal resistances decreased. Cardiac output was again depressed at 30, 90, and 180 min. Brain blood flow decreased 25 +/- 19 % (P< 0.01) from baseline for the duration of the study. CONCLUSIONS: Thiopental acutely decreases cardiac output, and blood flows to muscle and fat tissue. The temporary return of cardiac output to baseline may be related to intestinal vasodilation. These blood flow alterations may influence the pharmacokinetics of thiopental.

Quantitation of depth of thiopental anesthesia in the rat.

BACKGROUND: In contrast to that of inhalational anesthetics, quantitation of anesthetic depth for intravenous agents has not been well defined. In this study, using rodents, the relationship between the constant plasma thiopental concentrations and the clinical response to multiple nociceptive stimuli were investigated characterizing the anesthetic state from light sedation to deep anesthesia and correlated to the degree of electroencephalogram (EEG) drug effect. METHODS: Thirty rats were instrumented with chronically implanted EEG electrodes, arterial and venous catheters. A computer-driven infusion pump was used to rapidly attain and then maintain constant, target plasma thiopental concentrations ranging from 7 to 100 micrograms/ml. Three different target plasma thiopental concentrations were achieved in each rat. Electroencephalographic effects were monitored with aperiodic waveform analysis. The following nociceptive stimuli were applied: (1) unprovoked righting reflex, (2) provoked righting reflex, (3) noise stimulus, (4) tail clamping with an alligator clip, (5) constant tail pressure with an analgesiameter, (6) corneal reflex, and (7) tracheal intubation. For tail clamping, tail pressure, and intubation, either purposeful extremity movement or abdominal muscle contraction response was noted to be present or absent. The clinical responses (present or absent) were modeled using logistic regression to estimate the Cp50, the plasma thiopental concentration with a 50% probability of no response. RESULTS: The following mean Cp50 values (95% confidence interval) were obtained: unprovoked righting reflex, 15.9 (15.1-16.6) micrograms/ml; provoked righting reflex, 21.4 (20.2-22.7) micrograms/ml; noise stimuli, 31.3 (29.7-33.0) micrograms/ml; tail clamp and limb movement, 38.3 (36.1-40.4) micrograms/ml; tail pressure and limb movement, 39.2 (37.1-41.3) micrograms/ml; tail pressure and abdominal muscle contraction, 52.5 (50.0- 55) micrograms/ml; tail clamping and abdominal muscle contraction, 56.1 (50.0-56.2) micrograms/ml; corneal reflex, 60.0 (56.6-63.4) micrograms/ml; and limb movement or muscle abdominal contraction response to intubation, 67.7 (59.2-76.1) micrograms/ml. At an EEG-effect of 9.1 and 2.2 waves/s, there was a 50% chance of limb movement response to tail clamping and tracheal intubation, respectively. There was a poor relationship between the plasma thiopental concentration and the percent increase of either heart rate or mean arterial blood pressure after applying either tail pressure or tail clamp stimuli. CONCLUSIONS: A range of nociceptive stimuli and their observed clinical responses can be used to quantitate thiopental anesthetic depth, ranging from light sedation to deep anesthesia (isoelectric EEG and unresponsive to intubation) in the rodent. Clinical response can be mapped to surrogate EEG measures.

Sexually dimorphic expression of pituitary growth hormone-releasing factor receptor in the rat.

Secretion of growth hormone (GH) exhibits marked sexual dimorphism in the rat. To examine the underlying mechanism that involves hypothalamic GH-releasing factor (GRF), we determined pituitary GRF receptor mRNA levels in male and female rats and compared their in vitro abilities to release GRF, an endogenous ligand for GRF receptor. Female rats expressed GRF receptor mRNA at a level of only 15% (P < 0.001) of that of male rats. Female rats also showed a 33% lower (P < 0.01) ability to release GRF than male rats. These results indicate that the GRF secretion and action system of female rats is characterized by the combined reduction in GRF receptor expression and GRF-releasing capacity compared with that of male rats. This could explain the in vivo finding that spontaneous, GRF-triggered GH pulses are of much lower amplitude in the female than in the male rat.

Plasma concentration clamping in the rat using a computer-controlled infusion pump.

We have developed a computer-controlled infusion pump to achieve rapidly and then maintain stable plasma thiopental concentrations in rats. Initially we derived the parameters of a triexponential pharmacokinetic model for thiopental, administered as a brief infusion to 10 rats, using nonlinear regression and standard pharmacokinetic equations. These parameters were incorporated into the pharmacokinetic model of a computer-controlled infusion pump. In a second group of animals this device was used to maintain three consecutive target thiopental concentrations ranging from 5 to 100 micrograms/ml in a stepwise fashion. Arterial blood gases were kept normal through controlled ventilation when necessary. The plasma thiopental concentrations in this second group of animals were generally higher than the target concentrations. The bias in pump performance (median prediction error) was +25%, and the inaccuracy (median absolute prediction error) was 26%. We fit the parameters of a three-compartment model to the plasma thiopental concentrations observed in the second group of animals. This produced a second set of thiopental pharmacokinetic parameters with the unique characteristic of having been derived from a computer controlled infusion study. These parameters were tested prospectively with a computer-controlled infusion pump in a third group of animals. This second set of thiopental pharmacokinetic parameters performed better, with a median prediction error of 0% and a median absolute prediction error of 15%. This study shows that it is possible to achieve rapidly and maintain steady plasma thiopental concentrations in the rat. Our results suggest that it is feasible to derive robust pharmacokinetic parameters from unusual drug dosing approaches, such as employed by a computer-controlled infusion pump.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebro-costo-mandibular syndrome. A case report and review of the literature.

A 7-month-old boy with the cerebro-costo-mandibular syndrome is presented. This is the first case report in an Oriental population. 15 reported cases in the literature are reviewed.