Stage-specific expression of mouse germ cell-less-1 (mGCL-1), and multiple deformations during mgcl-1 deficient spermatogenesis leading to reduced fertility

A mouse homologue of Drosophila germ cell-less, mouse germ cell-less-1 (mgcl-1), is highly expressed in the testis. Previous report revealed that the fertility of the mgcl-1(-/-) male mice is reduced significantly as a result of various morphological abnormalities in the sperm (Kimura et al., 2003). To elucidate the function of mgcl-1 in spermatogenesis, the expression of mGCL-1 in the wild-type testis was examined. Immunohistochemical studies demonstrated that mGCL-1 first appeared in the nuclei of the pachytene spermatocytes at stage VI of the seminiferous epithelium, and existed in those of spermatids until step 8 during spermatogenesis. mGCL-1 was not detectable after step 9 spermatids. The testicular cells and epididymal sperm were further analyzed morphologically using mgcl-1(-/-) mice. In the testis, deformed nuclei first occurred in the pachytene spermatocytes at stage VI, which is consistent with the time of the first appearance of the mGCL-1 protein in the wild-type testis. Abnormal nuclei and acrosomes were found in spermatids after step 5, and nuclei of the spermatids and epididymal sperm were frequently invaginated. In addition, variously deformed sperm such as bent-neck, multi-headed or multi-nucleated sperm were observed in the mgcl-1(-/-) cauda epididymidis. However, several key structures such as the acroplaxome marginal ring (Kierszenbaum et al., 2003), postacrosomal sheath, and posterior ring apparently formed. In addition, MN7 and MN13, essential substances for fertilization that are located in sperm heads, were detectable in the mgcl-1 null sperm. These observations provide important insights into the mechanisms regulating the nuclear architecture and causes of human infertility.     

Hemodynamic differences between the awake and anesthetized conditions in normal calves

There is insufficient information in the literature about baseline circulatory parameters in normal calves in the anesthetized versus postoperative awake conditions under which a large volume of medical research is conducted. Eleven calves (mean body weight, 78.1?±?14.3?kg) were implanted with a flow probe and fluid-filled pressure lines to measure cardiac output (CO), aortic (AoP), central venous (CVP), pulmonary arterial (PAP), and left atrial pressures (LAP). Systemic (SVR) and pulmonary vascular resistance (PVR) were also calculated. We obtained the above hemodynamic data (n?=?11) and epicardial echocardiography (n?=?7) during open-chest surgery under isoflurane anesthesia. After full recovery from surgery, animals were evaluated in the awake condition on postoperative days 6-9 using transthoracic echocardiography (n?=?7) and the hemodynamic monitoring lines and probes noted (n?=?11). CO, AoP, and PAP levels in the anesthetized condition were significantly lower than in the awake condition. Other hemodynamic parameters (CVP, LAP, SVR, and PVR) were not significantly different. In conclusion, data from this study quantify changes in CO, AoP, and PAP in anesthetized calves that may affect the hemodynamic response to experimental therapeutics such as new cardiac assist devices, prosthetic valves, and surgical interventions. Our study also provides baseline data for the translation of the hemodynamic data obtained in acute in vivo calf studies to that of an awake subject.     

Facilitation of the soleus stretch reflex induced by electrical excitation of plantar cutaneous afferents located around the heel

Previous studies have demonstrated that plantar cutaneous afferents can adjust motoneuronal excitability, which may contribute significantly to the control of human posture and locomotion. However, the role of plantar cutaneous afferents with respect to their location specificity in modulating the mechanically induced stretch reflex still remains unclear. In the present study, it was hypothesized that electrical stimulation of the ipsilateral heel region of the foot is followed by a modulation of spinal excitability, leading to a facilitation of the soleus motor output. The study was performed to investigate the effect of excitation of plantar cutaneous afferents located around the heel on the soleus stretch reflex. The soleus stretch reflex was evoked by rotating the ankle joint in dorsiflexion direction at two different angular velocities of 50 and 200 degrees s(-1). A conditioning pulse train of non-noxious electrical stimulation was delivered to the plantar surface of the heel at different conditioning test intervals ranging from 5 to 100 ms. Excitation of plantar cutaneous afferents around the heel resulted in a pronounced facilitation of the soleus stretch reflex with magnitude and time course comparable for both velocities. This facilitation was manifested by a significant increase of reflex size for conditioning test intervals from 30 to 70 ms. The observed effect implies a potential functional role of cutaneous afferents in balance control conditions where the ankle is naturally disturbed, e.g., during step reactions to external perturbations.     

Dose-dependent effect of the Val66Met polymorphism of the brain-derived neurotrophic factor gene on memory-related hippocampal activity

Brain-derived neurotrophic factor (BDNF) plays a critical role in activity-dependent neuroplasticity underlying learning and memory in the hippocampus. Recent human studies have indicated that a common single nucleotide polymorphism of the BDNF gene, the Val66Met polymorphism, has impact on episodic memory, hippocampal morphology and memory-related hippocampal activity measured by functional magnetic resonance imaging (fMRI). However, two issues remain to be clarified: (1) whether the genotype effect of this polymorphism on memory-related brain activity is allele dose dependent and (2) whether the effect of this polymorphism in Asian population is the same as effects observed in Caucasian sample. To clarify these issues, we studied the relationship of the Val66Met polymorphism genotype and hippocampal activity during episodic memory task using fMRI in healthy 58 biologically unrelated Japanese. Although there was no genotype effect on episodic memory function obtained by behavioral assessments, fMRI measurements revealed a significantly negative correlation between the dose of Met-BDNF allele and encoding related brain activity in the bilateral hippocampi and right parahippocampal gyrus. There was no genotype effect on retrieval related brain activity. These data indicated a genetic mechanism for normal variation in human memory and suggest effects of BDNF signaling on hippocampal function in humans.     

Acute in vivo evaluation of an implantable continuous flow biventricular assist system

An implantable biventricular assist device offers a considerable opportunity to save the lives of patients with combined irreversible right and left ventricular failure. The purpose of this study was to evaluate the hemodynamic and physiologic performance of the combined implantation of the CorAide left ventricular assist device (LVAD) and the DexAide right ventricular assist device (RVAD). Acute hemodynamic responses were evaluated after simulating seven different physiological conditions in two calves. Evaluation was performed by fixing the speed of one individual pump and increasing the speed of the other. Under all conditions, increased LVAD or RVAD speed resulted in increased pump flow. The predominant pathophysiologic effect of independently varying DexAide and CorAide pump speeds was that the left atrial pressure was very sensitive to increasing RVAD speed above 2,400 rpm, whereas the right atrial pressure demonstrated much less sensitivity to increasing LVAD speed. An increase in aortic pressure and RVAD flow was observed while increasing LVAD speed, especially under low contractility, ventricular fibrillation, high pulmonary artery pressure, and low circulatory blood volume conditions. In conclusion, a proper RVAD-LVAD balance should be maintained by avoiding RVAD overdrive. Additional studies will further investigate the performance of these pumps in chronic animal models.     

Technical evaluation of dialysate flow in a newly designed dialyzer

Rexeed was developed by Asahi Kasei Medical using wave-shaped hollow fibers, a full baffle, and a short taper housing to improve dialysate flow. The present study is clarifies improvement in dialysate flow with Rexeed-15 compared with that of a conventional dialyzer. Dialysate flow was evaluated by the pulse-response method. Dialysate pressure and tracer concentration were measured at a blood-side flow rate (QBeta) of 200 ml/min, a dialysate-side flow rate (QD) of 500 ml/min, and a net filtration rate (QF) of 0 ml/min using needles placed in the test dialyzer. Dialyzer performance was evaluated by measuring urea and vitamin B12 clearance at QB = 200 and 400 ml/min, QD = 300-800 ml/min, and QF = 0 ml/min. In the conventional dialyzer, dialysate channeling was observed. In contrast, Rexeed-15 had a uniform dialysate flow. Urea and vitamin B12 clearance with Rexeed-15 was slightly sensitive to QD. The overall mass transfer coefficient for urea with Rexeed-15 was more than 50% higher than that of the conventional dialyzer, indicating the possibility of reduced dialysate usage with Rexeed. Rexeed has a highly optimal dialysate flow, due to the wave-shaped hollow fibers and the new housing, and gives increased clearance for lower-molecular-weight substances.     

In vivo evaluation of a new surfactant polymer coating mimicking the glycocalyx of endothelial cells

The purpose of this study was to demonstrate that a proprietary surfactant polymer (SP) coating does not adversely affect the hemodynamic performance of cardiopulmonary bypass (CPB) or gas exchange in oxygenators. The new coating was applied to a CPB circuit including cannulae, reservoir, oxygenator, and blood pump implanted into 12 pigs, divided into groups with either coated or noncoated pumps. CPB flow was maintained at a fixed level of approximately 2.4 L/min for 6 hours with full heparinization. Hemodynamic data and pump performance were recorded every hour, and blood samples were taken every 2 hours. After sacrifice, the CPB circuit and major organs were macroscopically examined. There was no significant difference in the oxygen transfer rate between the two groups. The coating did not adversely affect oxygenator inlet or outlet pressures. There was no significant difference between the two groups in microthrombi seen in the oxygenators. No thromboemboli were noted in the major organs on gross or histologic examination. In conclusion, this new SP coating did not decrease gas exchange performance, and its biocompatibility evaluations revealed no differences between coated and noncoated groups under aggressive heparin use.     

Cleveland clinic CorAide blood pump circulatory support without anticoagulation

The Cleveland Clinic CorAide left ventricular assist system consists of a permanently implantable centrifugal pump in which the rotating assembly is completely suspended and noncontacting. A series of chronic animal in vivo studies were conducted to evaluate the biologic effects of CorAide circulatory support without the use of anticoagulation therapy. The CorAide pump was implanted in six calves (five calves for 21 to 32 days and one calf for 95 days). The first five calves received intravenous heparin during the early postoperative periods (2-7 days). Heparin administration was then discontinued and no other anticoagulant drugs were used for the duration of the experiments. The last calf did not receive any anticoagulant except for a bolus dose of heparin (200 U/kg) during surgery. Hemodynamics were stable in all six calves, with a mean pump flow of 5.6+/-1.2 L/min and mean arterial pressure of 100+/-4 mm Hg. The blood pump surfaces were clean of thrombus in all six calves. Significant findings at autopsy were limited to one case of renal infarction. There was no incidence of mechanical failure, bleeding, or device infection. The CorAide pump can be safely run with minimal or no anticoagulant therapy.