Estrogen decreases levels of calcineurin in rat amygdala and hippocampus

We examined the effects of estradiol benzoate (E2) on the protein expression of calcineurin in amygdaloid and hippocampal structures of ovariectomized (OVX) rats. Significant decreases in levels of calcineurin immunolabeling were seen in the medial and basomedial, but not central or basolateral, amygdala. Estrogen also reduced calcineurin immunoreactivity in the CA1 region of the hippocampus, but not in the CA3 region, hilus or ventral or dorsal dentate gyrus structures of hippocampus. These results indicate that E2 acts on calcineurin in a neuroanatomically specific manner and may be involved in estrogen-mediated regulation of gene expression.     

Illness experience,depression, and anxiety in chronic fatigue syndrome

Objective: Given the high rate of psychiatric comorbidity with chronic fatigue syndrome (CFS), we considered two possible correlates of anxiety and depression: lack of illness legitimization and beliefs about limiting physical activity. Method: A total of 105 people diagnosed with CFS reported on their experiences with medical professionals and their beliefs about recovery and completed the depression and anxiety subscales of the Brief Symptom Inventory. Results: Those who said that their physician did not legitimize their illness (36%) had higher depression and anxiety scores (P's<.05) than their counterparts. Those who believed that limiting their physical exertion was the path to recovery (55%) had lower depression and anxiety scores (P's<.01) than their counterparts. Conclusion: Lack of illness legitimization ranked high as a source of dissatisfaction for CFS patients, and it may aggravate psychiatric morbidity. Many CFS patients believed that staying within what they felt to be their physical limits would improve their condition. This belief, and possibly an accompanying sense of control over their symptoms, may alleviate psychiatric morbidity.     

Inhibition of GABA-gated chloride channel function by arachidonic acid

The effects of arachidonic acid and its metabolites on gamma-aminobutyric acid (GABAA) receptor function were determined in rat cerebral cortical synaptoneurosomes. Incubation of synaptoneurosomes with phospholipase A2 decreased muscimol-induced 36Cl- uptake. Arachidonic acid, the major unsaturated fatty acid released by phospholipase A2, also inhibited muscimol-induced 36Cl uptake. Similar inhibition was obtained with other unsaturated fatty acids (docosahexaenoic, oleic) but not with saturated fatty acids (stearic, palmitic). The effect of arachidonic acid on muscimol responses was inhibited by bovine serum albumin (BSA), and BSA enhanced muscimol responses directly, indicating the generation of endogenous arachidonic acid in the synaptoneurosome preparation. The generation of endogenous arachidonic acid was also indicated by the ability of 2 inhibitors of arachidonic acid metabolism, indomethacin and nordihydroguaiaretic acid (NDGA), to inhibit muscimol-induced 36Cl uptake. We conclude that arachidonic acid probably has both direct and indirect actions on muscimol responses since both enzyme inhibitors inhibited muscimol responses but did not prevent the effect of exogenously added arachidonic acid. In additional experiments, arachidonic acid metabolites generated by cyclooxygenase, prostaglandins D2, E2 and F2 alpha, each decreased muscimol responses; prostaglandins F2 alpha was the most potent inhibitor. Since the unsaturated fatty acids and their metabolites are most susceptible to peroxidation, a generating system of superoxide radicals was tested on muscimol responses. A combination of xanthine and xanthine oxidase inhibited muscimol-induced 36Cl uptake in a concentration-dependent manner. We propose that the inhibition of GABAA neurotransmission by arachidonic acid and its metabolites can lead to increased neuronal excitability. This mechanism may play an important role in the development of neuronal damage following seizures or cerebral ischemia.     

Screening for proteins with polyglutamine expansions in autosomal dominant cerebellar ataxias

Expansion of trinucleotide CAG repeats coding for polyglutamine has been implicated in five neurodegenerative disorders, including spinocerebellar ataxia (SCA) 1 and SCA3 or Machado-Joseph disease (SCA3/MJD), two forms of type I autosomal dominant cerebellar ataxias (ADCA). Using the 1C2 antibody which specifically recognizes large polyglutamine tracts, particularly those that are expanded, we recently reported the detection of proteins with pathological glutamine expansions in lymphoblasts from another form of ADCA type I, SCA2, as well as from patients presenting with the distinct phenotype of ADCA type II. We now have screened a large series of patients with ADCA or isolated cases with cerebellar ataxia, for the presence of proteins with polyglutamine expansions. A 150 kDa SCA2 protein was detected in 16 out of 40 families with ADCA type I. This corresponds to 24% of all ADCA type I families, which is much more frequent than SCA1 in this series of patients (13%). The signal intensity of the SCA2 protein was negatively correlated to age at onset, as expected for an expanded and unstable trinucleotide repeat mutation. The disease segregated with markers closely linked to the SCA2 locus in all identified SCA2 families. In addition, a specific 130 kDa protein, which segregated with the disease, was detected in lymphoblasts of patients from nine families with ADCA type II. It was also visualized in the cerebral cortex of one of the patients, demonstrating its translation in the nervous system. Finally, no new disease-related proteins containing expanded polyglutamine tracts could be detected in lymphoblasts from the remaining patients with ADCA or isolated cases with cerebellar ataxia.      

Misexpression screen delineates novel genes controlling Drosophila lifespan

In an initial preliminary screen we identified factors associated with controlling Drosophila aging by examining longevity in adults where EP elements induced over-expression or antisense-RNA at genes adjacent to each insertion. Here, we study 45 EP lines that initially showed at least 10% longer mean lifespan than controls. These 45 lines and a daughterless (da)-Gal4 stock were isogenized into a CS10 wild-type background. Sixteen EP lines corresponding to 15 genes significantly extended lifespan when their target genes were driven by da-Gal4. In each case, the target genes were seen to be over-expressed. Independently derived UAS-gene transgenic stocks were available or made for two candidates: ImpL2 which is ecdysone-inducible gene L2, and CG33138, 1,4-alpha-glucan branching enzyme. With both, adult lifespan was increased upon over-expression via the GeneSwitch inducible Gal4 driver system. Several genes in this set of 15 correspond to previously discovered longevity assurance systems such as insulin/IGF-1 signaling, gene silencing, and autophagy; others suggest new potential mechanisms for the control of aging including mRNA synthesis and maturation, intracellular vesicle trafficking, and neuroendocrine regulation.     

Fetal islet xenotransplantation in rodents and primates

β cell replacement in IDDM by transplantation of either isolated adult islets of Langerhans or of proliferating immature islet tissue from fetal pancreas are potential ways of curing this disease. Because of the dearth of human cadaver donors adult allogeneic islets are scarce and in most Western societies availability of human fetal tissue of suitable maturity is also uncommon. The use of xenogeneic islets from domestic species already widely used for human consumption, e.g. pigs, could overcome this scarcity but xenogeneic tissues are faced with major problems of graft rejection. Hyperacute rejection (HAR) is the main cause of destruction of immediately vascularised xenografts and is caused by the interaction of natural cross-reactive antibodies with donor endothelial cells. Neovascularized islet grafts do not have donor EC as the target for HAR and are not subjected to this problem but are still acutely rejected. The mechanism of this destruction is still poorly understood but is clearly T cell dependent. However, current immunosuppression that is usually adequate for control of allograft rejection generally does not prevent xenograft rejection. A better understanding of the ways in which xenoantigens are recognised and of the nature of the immune response they initiate is fundamental to the development of appropriate strategies for the safe and effective control of xenograft rejection. The studies summarized herein describe the response of mice and primates to a challenge with fetal pig pancreas grafts. The rejection response that develops is different from that seen against a challenge with fetal allogeneic islets. Although the xenograft response is highly T cell dependent the actual effectors of graft damage appear to be different from those that provoke allograft destruction and include macrophages and granulocytes, particularly eosinophils, and possibly non-classical T cells.     

Identification of novel mutations in the MTM1 gene causing severe and mild forms of X-linked myotubular myopathy.

X-linked myotubular myopathy (XLMTM) is a congenital muscular disease characterized by severe hypotonia and generalized muscle weakness, leading in most cases to early postnatal death. The gene responsible for the disease, MTM1, encodes a dual specificity phosphatase, named myotubularin, which is highly conserved throughout evolution. To date, 139 MTM1 mutations in independent patients have been reported, corresponding to 93 different mutations. In this report we describe the identification of 21 mutations (14 novel) in XLMTM patients. Seventeen mutations are associated with a severe phenotype in males, with death occurring mainly before the first year of life. However, four mutations-three missense (R241C, I225T, and novel mutation P179S) and one single-amino acid deletion (G294del)-were found in patients with a much milder phenotype. These patients, while having a severe hypotonia at birth, are still alive at the age of 4, 7, 13, and 15 years, respectively, and display mild to moderate muscle weakness.     

Sensitivity of knee soft-tissues to surgical technique in total knee arthroplasty

Restricted range of motion and excessive laxity are both potential complications of total knee arthroplasty (TKA). During TKA surgery, the surgeon is frequently faced with the question of how tightly to implant the prosthesis. The most common method of altering implantation tightness is to vary the thickness of the polyethylene inlay after the bone cuts have been made and the trial components inserted. We have sought to quantify how altering the polyethylene thickness may affect post-operative soft tissue tension for a range of prosthetic designs.Four different prosthetic designs were implanted into fresh-frozen cadaveric knee joints. All four designs were implanted in the standard manner, with a 100 Newton distraction force used to set soft tissue balance. The tibiofemoral force was then recorded at 15° intervals throughout the passive flexion range. After the standard implantation of each prosthesis, the tibial component was raised or lowered to mimic increasing and decreasing the polyethylene thickness by 2 mm and the force measurements repeated.Tibiofemoral force in extension correlated with implantation tightness for all prosthesis designs. Between 15° and 90°of knee flexion, all four designs were insensitive to changes in implantation tightness. Beyond 90° the effect was more notable in rotating platform mobile-bearing and cruciate-retaining prostheses than in posterior-stabilised mobile-bearing designs.The findings of this research may be useful in assisting surgical decision-making during the implantation of TKA prostheses.