Effects of castration and chronic steroid treatments on hypothalamic gonadotropin-releasing hormone content and pituitary gonadotropins in male wild-type and estrogen receptor-alpha knockout mice

Testicular androgens are integral components of the hormonal feedback loops that regulate circulating levels of LHbeta and FSH. The sites of feedback include hypothalamic areas regulating GnRH neurons and pituitary gonadotropes. To better define the roles of androgen receptor (AR), estrogen receptor-alpha (ERalpha), and estrogen receptor-beta (ERbeta) in mediating feedback effects of sex steroids on reproductive neuroendocrine function, we have determined the effects of castration and steroid replacement therapy on hypothalamic GnRH content, pituitary LHbeta and FSHbeta messenger RNA (mRNA) levels, and serum gonadotropins in male wild-type (WT) and estrogen receptor-alpha knockout (ERKO) mice. Hypothalami from intact WT and ERKO males contained similar amounts of GnRH, whereas castration significantly reduced GnRH contents in both genotypes. Replacement therapy with estradiol (E2), testosterone (T), or dihydrotestosterone (DHT) restored hypothalamic GnRH content in castrated (CAST) WT mice; only the androgens were effective in CAST ERKOs. Analyses of pituitary function revealed that LHbeta mRNA and serum LHbeta levels in intact ERKOs were 2-fold higher than those in intact WT males. Castration increased levels of LHbeta mRNA (1.5- to 2-fold) and serum LHbeta (4- to 5-fold) in both genotypes. Both E2 and T treatments significantly suppressed LHbeta mRNA and serum LH levels in CAST WT males. However, E2 was completely ineffective, and T was only partially effective in suppressing these two indexes in the CAST ERKO males. DHT treatments stimulated a 50% increase in LHbeta mRNA and serum LH levels in WT males, whereas serum LH was significantly suppressed in DHT-treated ERKO males. Although the pituitaries from intact ERKO males contained similar amounts of FSHbeta mRNA, serum FSH levels were 20% higher than those in the intact WT males. Castration increased FSHbeta mRNA levels only in WT males, but significantly increased serum FSH levels in both genotypes. Both E2 and T treatments significantly suppressed serum FSH in CAST WT males, whereas only E2 suppressed FSHbeta mRNA. DHT treatments of CAST WT mice stimulated a small increase in serum FSH, but failed to alter FSHbeta mRNA levels. None of the steroid treatments exerted any significant effect on FSHbeta mRNA or serum FSH levels in CAST ERKOs. These data suggest that hypothalamic GnRH contents can be maintained solely through AR signaling pathways. However, normal regulation of gonadotrope function requires aromatization of T and activation of ERalpha signaling pathways in the gonadotrope. In addition, serum FSH levels in male ERKOs appear to be regulated largely by nonsteroidal testicular factors such as inhibin. Finally, these data suggest that hypothalamic ERbeta may not be involved in mediating the negative feedback effects of T on serum LH and FSH in male mice.     

Klebsiella pneumoniae panophthalmitis: a possible complication of endoscopic variceal injection sclerotherapy

Complication of endoscopic variceal injection sclerotherapy for esophageal variceal hemorrhage is not unusual. However, sclerotherapy complicated panophthalmitis was never reported before. We report such an unusual complication and discuss its possible mechanism and treatment.     

A new method to isolate large numbers of rabbit osteoclasts and osteoclast-like cells: application to the characterization of serum response element binding proteins during osteoclast differentiation

We have developed a new method that allows the purification of large numbers of both authentic osteoclasts (OCs) and in vitro differentiated osteoclast-like cells (OCLs) from rabbits. We characterized the OCLs in terms of the expression of different phenotypic markers of OC differentiation and their ability to resorb bone. The method provides a system for performing biochemical and molecular studies of OC differentiation and function in a single species. We used this system to characterize the effect of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) on the expression of proteins that bind to the serum response element (SRE) of the c-fos promoter. We found that OCLs and OCs displayed similar SRE-binding activities, including the serum response factor (SRF). This pattern is established in a time-dependent and cell-specific manner in response to long-term treatment of rabbit bone marrow by 1,25(OH)2D3. Thus, 1,25(OH)2D3 can modulate SRF and/or SRF-related protein. This finding may contribute to understanding the role of c-Fos in the regulation of OC differentiation.     

Familial and metabolic factors related to blood pressure in Pima Indian children

High blood pressure, abnormal glucose tolerance, and obesity are frequently associated with each other, but the mechanism of these associations is poorly understood. Studying them in children may help in understanding the pathogenesis of hypertension. Blood pressure, height, weight, and plasma glucose and serum insulin concentrations during a 75-g oral glucose tolerance test were measured in 1,698 Pima Indian children aged 6-17 years who participated in an ongoing epidemiologic study. Weight relative to height was used as an index of obesity. The parents of many of the children were also examined. Fasting and 2-hour glucose and insulin concentrations, adjusted for age, sex, and relative weight, were positively related to systolic blood pressure but not to diastolic blood pressure. Relative weight, 2-hour glucose, and fasting insulin concentrations were independently and significantly associated with systolic blood pressure in a stepwise regression analysis that included age and sex. After parental hypertension was taken into account, maternal but not paternal non-insulin-dependent diabetes mellitus, controlled for the child's relative weight and glucose and insulin concentrations, was significantly associated with higher blood pressure in children. The stronger association with maternal diabetes suggests a greater sharing of environmental factors between mother and child than between father and child, but familial similarities in obesity and glucose and insulin concentrations, the diabetic intrauterine milieu, and shared environmental factors probably all contribute to this association.     

Multimouth surfaces for synthetic actor animation

Most parts of the human body are cylindrical in shape. Generalized cylinders, with two cross-sectional openings, are a logical choice to represent these cylindrical shapes. However, a variety of human body regions can be visualized as surfaces with multiple openings or multimouth (MM) surfaces. Some examples of such surfaces are the pelvis, the chest, and the palms of the hands. We investigated the suitability of non-uniform rational B-spline (NURBS) formulation for creating multimouth surfaces. Two techniques, the surface wrapping model and the garland model, are presented.     

Activation of bovine lymphocyte subpopulations by staphylococcal enterotoxin C

Staphylococcus aureus is a major mastitis-causing pathogen in cattle. The chronic nature of bovine staphylococcal mastitis suggests that some products or components of S. aureus may interfere with the development of protective immunity. One class of molecules that could be involved are superantigens (SAgs). Although a significant number of mastitis isolates produce SAgs, the effect of these molecules on the bovine immune system is unresolved. To determine if immunosuppression caused by SAgs could play a role in pathogenesis, we monitored bovine lymphocytes exposed to staphylococcal enterotoxin C1 (SEC1). Activation of bovine lymphocytes by either SEC1 or concanavalin A (ConA) was influenced by the gammadelta/alphabeta T-cell ratio in the culture. Compared to ConA-induced stimulation, cultures stimulated with SEC1 generated small numbers of CD4+ alphabeta T cells expressing high levels of interleukin-2 receptor alpha chain (IL-2R alpha) and major histocompatibility complex class II (MHCII), suggesting that SAg exposure does not lead to full activation of these cells. This state of partial activation was most pronounced in cultures with a high gammadelta/alphabeta ratio. In contrast, significant numbers of CD8+ alphabeta T cells expressed high levels of IL-2R alpha and MHCII, regardless of the gammadelta/alphabeta ratio and the stimulant used. CD8+ blasts in cultures stimulated with SEC1 also expressed another activation marker, ACT3, previously detected predominantly on thymocytes and CD4+ T cells. Although gammadelta CD2- and CD2+ T cells expressed MHCII and IL-2R alpha following stimulation with SEC1, only a few cells increased to blast size, suggesting that they were only partially activated. The results suggest ways in which SAgs might facilitate immunosuppression that promotes the persistence of bacteria in cattle and contributes to chronic intramammary infection.     

Abdominal and thoracoabdominal aortic aneurysm

Most abdominal aortic aneurysms (AAA) and thoracoabdominal aortic aneurysms (TAAA) are asymptomatic and are found on physical exam or incidentally during radiological studies for other indications. These aneurysms are repaired primarily because their risk of rupture increases geometrically as the size exceeds 5 cm. The potential morbidity of intraoperative visceral and spinal ischemia involved with TAAA repair may be reduced with various adjunctive maneuvers.     

Decreased protein kinase C activation mediates inhibitory effect of norathyriol on serotonin-mediated endothelial permeability

We examined the mechanisms of norathyriol on the serotonin-induced increased permeability of rat heart endothelial cell monolayers. The present study showed that the activation of rat heart endothelial cell protein kinase C by phorbol myristate acetate led to the dose-dependent increase in endothelial permeability to albumin, an effect that was inhibited by staurosporine (a protein kinase inhibitor). Staurosporine also attenuated the serotonin-induced increase in permeability. Norathyriol abolished both serotonin- and phorbol myristate acetate-induced permeability. We investigated whether norathyriol, by inhibiting protein kinase C activation, attenuated the serotonin-induced permeability. Immunofluorescence studies demonstrated that norathyriol prevented the redistribution of protein kinase C isozymes following stimulation with serotonin. Western blot analysis showed that norathyriol significantly inhibited the serotonin-induced translocation of the alpha protein kinase C isozyme from the cytosolic to the particulate fraction. In conclusion, norathyriol attenuates the serotonin-induced permeability of rat heart endothelial cells to macromolecules in association with inhibition of protein kinase C activation. This decrease in endothelial cell permeability may be one of the mechanisms for the protective effects of norathyriol against edema formation in response to inflammatory agonists in vivo.