Functional MRI mapping of brain activation during visually guided saccades and antisaccades: cortical and subcortical networks

Antisaccade tasks require a subject to inhibit a saccade toward a briefly appearing peripheral target and instead to immediately generate a saccade to an equivalent point in the opposite hemifield. Using functional magnetic resonance imaging (fMRI), we investigated the neural networks required to inhibit reflexive saccades and to voluntarily generate saccades. The results demonstrated that saccade and antisaccade tasks often bilaterally activate frontal, parietal and supplementary eye fields, lenticular nuclei and occipital cortex. Additional activation of bilateral dorsolateral prefrontal cortices, supramarginal gyri, anterior cingulate cortices and thalamus was observed during antisaccade tasks. These results indicate that fronto-parietal and fronto-striato-thalamo-cortical circuits are involved in antisaccade tasks. The fronto-parietal circuit is thought to be related to the planning of saccadic eye movements that involve attentional control, while the fronto-striato-thalamo-cortical circuits connect to cortical region as a feedback network. We speculate that the abnormalities in spatial attention and eye movement control observed in schizophrenia stem from dysfunctions in the fronto-parietal and fronto-striato-thalamo-cortical circuits.     

The effects of the reported active metabolite of methoxychlor, 2,2-bis(p-hydroxyphenyl)-1,1,1-trichloroethane, on testosterone formation by cultured Leydig cells from young adult rats

Methoxychlor (MC) is an insecticide that is currently used on a variety of agricultural crops, especially following the ban of 2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane (DDT) use in the United States. Following in vivo administration, MC is converted to 2,2-bis(p-hydroxyphenyl)-1,1,1-trichloroethane (HPTE), which is proposed to be the active agent. Both MC and HPTE have been demonstrated to exhibit weak estrogenic and antiandrogenic activities, and they are thought to exert their effects through estrogen or androgen receptors, respectively. A recent study reported that HPTE inhibited both basal and hCG-stimulated testosterone formation by immature and adult cultured rat Leydig cells and that this effect was mediated through the estrogen receptor. In the current studies, we examined the effects of HPTE on basal and hCG-stimulated testosterone formation by cultured Leydig cells from young adult rats. In addition, we evaluated whether the effects of HPTE on rat Leydig cell testosterone biosynthesis were mediated through the estrogen receptor as an estrogen agonist or the androgen receptor as an antiandrogen. The current studies demonstrated that HPTE inhibited both basal and hCG-stimulated testosterone formation in a dose-dependent manner with significant declines in testosterone being observed at approximately 100 nM. The effects of HPTE were localized to the cholesterol side-chain cleavage step; however, these effects were not mediated through the classic estrogen receptor or by its acting as an antiandrogen, the currently recognized modes of action of MC and HPTE.     

Predictive factors for remission and death in 73 patients with autoimmune hepatitis in Japan

The prognosis of patients with autoimmune hepatitis (AIH) has not been clearly defined. The aim of this study was to define the prognostic factors of AIH in a population with long-term follow-up in Japan. Seventy-three patients who were diagnosed as having type 1 AIH between January, 1972 - August, 1999 were enrolled in this study. Initial treatment included prednisolone (PSL) (n=62), other drug regimens (n=7), and none (n=4). We examined the relation between several factors obtained at diagnosis in relation to disease activity found at the final observation point (January, 2000 - April, 2000). Multivariate logistic regression and Cox regression were used for statistical analysis. During the observation period, 8 patients died of the following: hepatic failure (n=4), hepatocellular carcinoma (n=1), severe infection (n=1), and unknown causes (n=2). At the end point, the number of patients in complete remission was 13, those with a normal alanine aminotransferase (ALT) level requiring some treatment was 35, and those with an abnormal ALT level despite medication was 17. Factors related to remission were total bilirubin (TB) (Odds ratio, 0.87), and immunoglobulin G (IgG) (Odds ratio, 1.00). Factors related to death were the aspartate aminotransaminase (AST)/ALT ratio (Odds ratio, 11.67) and response to initial PSL regimen (Odds ratio, 0.03). The results of this study show an importance of achieving a good PSL response at onset, and that initial TB, the AST/ALT ratio, and IgG levels are useful for therapeutic strategy.     

Mitochondrial generation of reactive oxygen species and its role in aerobic life

Mitochondria are the major site for the generation of ATP at the expense of molecular oxygen. Significant fractions (approximately 2%) of oxygen are converted to the superoxide radical and its reactive metabolites (ROS) in and around mitochondria. Although ROS have been known to impair a wide variety of biological molecules including lipids, proteins and DNA, thereby causing various diseases, they also play critical roles in the maintenance of aerobic life. Because mitochondria are the major site of free radical generation, they are highly enriched with antioxidants including GSH and enzymes, such as superoxide dismutase (SOD) and glutathione peroxidase, on both sides of their membranes to minimize oxidative stress in and around this organelle. The present work reviews the sites and mechanism of ROS generation by mitochondria, mitochondrial localization of Mn-SOD and Cu,Zn-SOD which has been postulated for a long time to be a cytosolic enzyme. The present work also describes that a cross-talk of molecular oxygen, nitric oxide (NO) and superoxide radicals regulates the circulation, energy metabolism, apoptosis, and functions as a major defense system against pathogens. Pathophysiological significance of ROS generation by mitochondria in the etiology of aging, cancer and degenerative neuronal diseases is also described.     

An occupational reproductive research agenda for the third millennium

There is a significant public health concern about the potential effects of occupational exposure to toxic substances on reproductive outcomes. Several toxicants with reported reproductive and developmental effects are still in regular commercial or therapeutic use and thus present potential exposure to workers. Examples of these include heavy metals, organic solvents, pesticides and herbicides, and sterilants, anesthetic gases, and anticancer drugs used in health care. Many other substances are suspected of producing reproductive or developmental toxicity but lack sufficient data. Progress has been limited in identifying hazards and quantifying their potencies and in separating the contribution of these hazards from other etiologic factors. Identifying the causative agents, mechanisms by which they act, and any potential target populations, present the opportunity to intervene and protect the reproductive health of workers. The pace of laboratory studies to identify hazards and to underpin the biologic plausibility of effects in humans has not matched the pace at which new chemicals are introduced into commerce. Though many research challenges exist today, recent technologic and methodologic advances have been made that allow researchers to overcome some of these obstacles. The objective of this article is to recommend future directions in occupational reproductive health research. By bridging interdisciplinary gaps, the scientific community can work together to improve health and reduce adverse outcomes.     

New method of catheter-port system implantation in hepatic arterial infusion chemotherapy

BACKGROUND: This report describes a novel method of implantation of the catheter-port system in hepatic arterial infusion chemotherapy, which is the inferior epigastric arterial approach. METHODS: Using this method, the length of incision is about 3 cm in lower abdomen. The inferior epigastric artery is exposed above the inguinal ligament. The half of the artery is cut, and a vascular sheath is inserted into the external iliac artery along a guide wire. A catheter is inserted into the hepatic artery through the vascular sheath. Coil occlusion of nontarget artery is performed by the technique of interventional radiology. Then the vascular sheath is removed and the catheter is fixed to the inferior epigastric artery. A port is connected to the catheter and placed above the incision in the lower abdomen. CONCLUSIONS: Using this method, the hip joint can be moved freely and port-related complications are few, which contributes to a good quality of life of patients during the therapy. The inferior epigastric arterial approach may give a benefit to those who are treated with hepatic arterial infusion chemotherapy.