Clozapine as a drug of dependence

Rationale: In schizophrenics, clozapine has been reported to induce various withdrawal signs and rapid onset relapse to psychosis on cessation of chronic treatment. Objective: The study was designed to develop an animal model of one aspect of clozapine tolerance and withdrawal using core body temperature measures. Methods: Two groups of 15 female Wistar rats were treated chronically (b.i.d.) with clozapine at 6 or 12 mg/kg per injection for 21 days prior to cessation of drug treatment, withdrawal being studied over 4 consecutive days. Body temperatures were assessed daily throughout the study. Results: Acutely, clozapine induced dose-related hypothermia, to which complete tolerance developed in both groups, the development of tolerance being more rapid in the group treated with 6 mg/kg per injection of clozapine. During withdrawal only the group treated chronically with 12 mg/kg per injection of clozapine showed rapid onset significant hyperthermia. This dissipated progressively over days, and was completely absent after 4 days of withdrawal. Conclusions: Clozapine induced a clear somatic withdrawal sign after chronic treatment. It is suggested that, in future research in both humans and animals, it is important to attempt to differentiate between clozapine withdrawal and clozapine withdrawal-induced relapse to psychosis. It is also important to characterise the clozapine withdrawal syndrome fully in animals; to establish the neurochemical mechanisms involved in such withdrawal; and to determine which novel antipsychotics are most efficacious in inducing clozapine-like withdrawal effects, in suppressing clozapine withdrawal, and in preventing relapse to psychosis in patients being transferred from clozapine to novel atypical antipsychotic drugs. Received: 14 May 1998/Final version: 14 September 1998     

Participation of the Fas-Signaling System in the Initiation of Germ Cell Apoptosis in Young Rat Testes after Exposure to Mono-(2-Ethylhexyl) Phthalate

The Fas-signaling system is composed of the interacting proteins Fas (CD95/APO-1) and Fas ligand (FasL, CD95L, APO-1L) and is proposed to act in the testis as a paracrine signaling mechanism by which FasL-expressing Sertoli cells initiate apoptosis of Fas-bearing germ cells. Here we describe alterations in the expression of Fas and FasL in the testis after the intimate physical association between Sertoli cells and germ cells is disrupted by exposure to the Sertoli cell toxicant mono-2-(ethylhexyl) phthalate (MEHP). Young, 28-day-old Fisher rats were treated with MEHP (2 g/kg po) and killed 0, 3, 6, and 12 h after exposure. Immunohistochemical analyses revealed a significant increase in the numbers of Fas-positive germ cells as well as increases in the expression of Sertoli cell FasL. Western blot analysis demonstrated a time-dependent increase in the production of the soluble form of FasL after MEHP exposure and suggests that it may participate in triggering apoptosis in germ cells that have lost their intimate association with the Sertoli cells. Measurement of Fas in cytosolic and membrane fractions of testis homogenates by Western blot analysis revealed a significant shift of Fas expression into the membrane fraction after MEHP exposure. Taken together, these observations indicate that the Fas-mediated paracrine signaling mechanism participates in triggering apoptosis of germ cells despite the loss of their close physical association with Sertoli cells. A working model is presented to explain the involvement of the Fas-system in stimulating germ cell apoptosis after MEHP exposure.     

Rotational behaviour and cGMP responses following manipulation of nigral mechanisms with chlordiazepoxide

Summary Unilateral stereotaxic injections of 1 g of the soluble benzodiazepine chlordiazepoxide hydrochloride into the predominantly GABA-containing zona reticulata of the substantia nigra of amphetamine-pretreated rats induced rotational behaviour similar to that seen following unilateral elevation of nigral GABA levels and amphetamine treatment; this effect was not seen following injections into the vicinity of the predominantly dopamine-containing zona compacta. Chlordiazepoxide-induced rotations were abolished by the GABA-antagonist picrotoxin. Both chlordiazepoxide and GABA depressed production of cyclic 3,5-guanosine monophosphate in samples of nigral tissue in vitro as estimated by radioimmunoassay. It is concluded that chlordiazepoxide may enhance GABA transmission within the substantia nigra, by some as yet unidentified mechanism, to create asymmetric activity in GABA-modulated neurones and hence induce rotation.     

Validating a New Non-penetrating Sham Acupuncture Device：Two Randomised Controlled Trials

IntroductionIn clinical trials of the efficacy of manualtreatm ents like surgery or acupuncture,control groups are comm only given‘sham’procedures.Sham procedures,inorder to be true placebos,must be 1) in-distinguishable from the real treatm entand 2 ) inactive.In acupuncture trials,various controls for the process of insert-ing a needle and stimulating it have beenused.These include needling off point orat inappropriate points[1 ,2 ] ,pricking orscratching with blunt needle[3,4 ] ,needlingw…     

Autoreactive, cytotoxic T lymphocytes specific for peptides derived from normal B-cell differentiation antigens in healthy individuals and patients with B-cell malignancies.

PURPOSE: To investigate potential immunotherapeutic strategies in B lymphocytic malignancies we looked for CTLs recognizing CD19 and CD20 epitopes. EXPERIMENTAL DESIGN: Three CD19 and CD20 peptides binding to HLA-A*0201 were identified and used to detect peptide specific CTLs by a quantitative real-time PCR to measure IFN-gamma mRNA expression in 23 healthy individuals and 28 patients (18 chronic lymphocytic leukemia (CLL), 7 follicular lymphoma, 2 acute lymphocytic leukemia, and 1 large cell lymphoma). Peptide-specific CTLs were expanded in culture with CD40-activated B cells to test lytic activity in three patients. RESULTS: In healthy individuals, CD8+ T-cell responses were detected in one to CD19(74-82), in three to CD20(127-135), and three to CD20(188-196). Seven of 27 patients (6 with CLL) had CD8+ T cells recognizing CD19(74-82). Seven patients responded to CD20(127-135) and three to CD20(188-196). All were CLL patients. CD19(74-82)-specific CTLs from three patients were expanded over 4 weeks. These cells were HLA-A*0201 specific and lytic for peptide-loaded antigen-presenting cells but not to malignant or unpulsed B cells. CONCLUSIONS: CTLs that recognize CD19 and CD20 epitopes exist in healthy individuals and may be increased in CLL patients. They are of low avidity and require high doses of peptide for activation. Strategies to increase T-cell avidity would be necessary for T-cell immunotherapeutic approaches using the peptides studied.     

c-erbB-2 related aggressiveness in breast cancer is hypoxia inducible factor-1alpha dependent.

c-erbB-2-positive breast carcinomas are highly aggressive tumors. In vitro data on breast cell lines showed that c-erbB-2 enhanced translational efficiency of hypoxia inducible factor-1alpha (HIF1alpha) production (Laughner et al., Mol Cell Biol 2001;21:3995-4005). We investigated the clinical correlate of this observation to assess whether c-erbB-2 expression was related to HIF1alpha expression, angiogenesis, and prognosis. A series of 180 breast carcinomas of known c-erbB-2 status (90 c-erbB-2-positive and 90 c-erbB-2-negative carcinomas) were stained immunohistochemically for HIF1alpha and CD31 endothelial cell antigen. c-erbB-2 positivity was clearly related to HIF1alpha protein expression and high angiogenesis. However, prognosis was decreased only in cases with simultaneous c-erbB-2 and HIF1alpha expression. If activation of c-erbB-2 in humans results in overexpression of HIF1alpha independently of conditions of hypoxia, as occur in experimental studies, this interaction may represent a main pathway conferring clinical aggressiveness to c-erbB-2-positive breast tumors.     

Insulin resistance is associated with decreased clinical status in cystic fibrosis

Patients with cystic fibrosis (CF) frequently have impaired glucose tolerance and progression to diabetes (DM) with clinical features of both insulin-dependent and non-insulin-dependent diabetes. One feature of non-insulin-dependent DM is decreased insulin sensitivity, also known as insulin resistance. The goal of this study was to determine whether patients with CF exhibit insulin resistance and to determine the potential effect of insulin resistance on clinical status. We also sought to determine whether insulin resistance is associated with a specific CF genotype. We studied 18 patients with CF (8 with normal glucose tolerance, 5 with impaired glucose tolerance, 5 with DM), and 20 lean control subjects matched for age, weight, and sex. All control subjects had normal glucose tolerance. The clinical status for each CF patient was determined according to a modified National Institutes of Health scoring system. Each subject underwent a three-step hyperinsulinemic euglycemic clamp (insulin doses of 10, 40, 120 mU/m ² per minute). Results from the 120 mU/m ² per minute infusion defined maximal glucose disposal rate (defined in milligrams per kilogram body weight per minute) at steady state with peripheral insulin levels 195 ± 20 mU/ml. Subjects with CF demonstrated insulin resistance (control subjects = 13.6 ± 1.1, patients with CF = 10.2 ± 1.6 mg/kg per minute; p = 0.003). When each subgroup was compared separately with control subjects, all subgroups were statistically insulin resistant (glucose disposal rate, patients with CF and normal glucose tolerance = 10.8; those with impaired glucose tolerance = 8.4; those with DM = 10.1 mg/kg per minute), and the patients with CF with impaired glucose tolerance were the most insulin resistant. When plotted versus glucose disposal rate, a striking positive correlation between worsened clinical status and insulin resistance ( r = 0.85) is demonstrated. Furthermore, there is no correlation between insulin resistance and fasting blood glucose, subject age, or percent ideal body weight (all r values not significant). In conclusion, patients with CF exhibit insulin resistance that is associated with worsened clinical status. We believe it is the combination of insulin resistance and decreased insulin secretion that is responsible for the high incidence of CF-related diabetes. (J Pediatr 1997;130:948-56)     

Serum vitamin D metabolite levels and the subsequent development of prostate cancer (Hawaii, United States)

Objectives: Because several serum studies of vitamin D metabolites have produced equivocal results on their relation to prostate cancer risk, the purpose of this study is to evaluate this association further.Methods: A nested case-control study in a cohort of 3,737 Japanese-American men examined from 1967 to 1970 was conducted in Hawaii (United States). At the time of examination, a single blood specimen was obtained, and the serum was frozen. After a surveillance period of over 23 years, 136 tissue-confirmed incident cases of prostate cancer were identified. Their stored sera and those of 136 matched controls were measured for the following: 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, calcium, phosphorus, and parathyroid hormone.Results: There were no notable differences between cases and controls in their median serum levels of the five laboratory measurements. Odds ratios (OR) for prostate cancer, based on the quartiles of serum levels in controls, were also determined. The ORs for the highest quartiles relative to the lowest were 0.8 (95 percent confidence interval [CI] = 0.4-1.8) for 25-hydroxyvitamin D and 1.0 (CI = 0.5-2.1) for 1,25-dihydroxyvitamin D.Conclusion: It is possible that the lack of sufficient numbers of study subjects with low vitamin D levels affected the results. Nonetheless, the findings suggest that there is a lack of a strong association between vitamin D and prostate cancer.