Differential inhibition by alpha-conotoxin-MII of the nicotinic stimulation of [3H]dopamine release from rat striatal synaptosomes and slices

The presynaptic nicotinic modulation of dopamine release from striatal nerve terminals is well established, but the subtype(s) of neuronal nicotinic acetylcholine receptor (nAChR) underlying this response has not been identified. Recently, alpha-conotoxin-MII has been reported to inhibit potently and selectively the rat alpha3beta2 combination of nAChR subunits. Here we have synthesised the peptide, confirmed its specificity, and examined its effect on the (+/-)-anatoxin-a-evoked release of [3H]dopamine from rat striatal synaptosomes and slices. Alpha-conotoxin-MII (112 nM) completely blocked acetylcholine-evoked currents of alpha3beta2 nAChRs expressed in Xenopus oocytes (IC50 = 8.0 +/- 1.1 nM). Pairwise combinations of other nicotinic subunits were not blocked by 112 nM alpha-conotoxin-MII. On perfused striatal synaptosomes and slices, alpha-conotoxin-MII dose-dependently inhibited [3H]dopamine release evoked by 1 microM (+/-)-anatoxin-a with IC50 values of 24.3 +/- 2.9 and 17.3 +/- 0.1 nM, respectively. The dose-response curve was shifted to the right with increasing agonist concentrations. However, the maximal inhibition of responses achieved by alpha-conotoxin-MII (112 nM) was 44.9 +/- 5.4% for synaptosomes and 25.0 +/- 4.1% for slices, compared with an inhibition by 10 microM mecamylamine of 77.9 +/- 3.7 and 88.0 +/- 2.1%, respectively. These results suggest the presence of presynaptic alpha3beta2-like nAChRs on striatal dopaminergic terminals, but the incomplete block of (+/-)-anatoxin-a-evoked [3H]dopamine release by alpha-conotoxin-MII also supports the participation of nAChRs composed of other subunits. The lower inhibition found in slices is consistent with an additional indirect nicotinic stimulation of dopamine release via an alpha-conotoxin-MII-insensitive nAChR.     

Assessment of correlation between skin target site free drug concentration and the in vivo topical antiviral efficacy in hairless mice for (E)-5-(2-bromovinyl)-2'-deoxyuridine and acyclovir formulations

Recently, we reported that the in vivo efficacy of acyclovir (ACV) formulations was a single valued function of skin target site free drug concentration (C) irrespective of the formulation compositions. A long-term objective of this research has been to generalize the C concept using model drugs which are similar to as well as different from ACV in their mechanism of actions. (Bromovinyl)deoxyuridine (BVDU) was selected as a model drug based on the reported similarity in its mechanism of action with ACV. The relationship between the C predictions and the in vivo efficacies for some topical formulations containing different concentrations (0.05-10%) of either ACV or BVDU in 95% DMSO as a vehicle with or without 5% Azone as skin permeation enhancer was examined. Hairless mice infected cutaneously with HSV-1 were used to quantitatively estimate the in vivo topical antiviral efficacy. A finite dose of the test antiviral formulation was applied twice a day for 4 days, starting the day after virus inoculation. On the fifth day, the lesions were scored and the efficacy values were calculated. For each formulation, in vitro flux experiments were performed in an in vivo-in vitro experimental design that closely approximated the in vivo study protocol. As was previously shown, with all ACV formulations, a good correlation was found between the C predictions and the in vivo topical efficacy. With the BVDU formulations, on the other hand, this was found not to be the case. BVDU formulations with 5% Azone were generally much more effective than those without Azone at comparable C values. This finding is believed to be the first of its kind showing that skin "permeation enhancers" may enhance efficacy by more than simply increasing skin permeation rates.     

Metabolism and metabolic actions of 6-methylpurine and 2-fluoroadenine in human cells

Activation of purine nucleoside analogs by Escherichia coli purine nucleoside phosphorylase (PNP) is being evaluated as a suicide gene therapy strategy for the treatment of cancer. Because the mechanisms of action of two toxic purine bases, 6-methylpurine (MeP) and 2-fluoroadenine (F-Ade), that are generated by this approach are poorly understood, mechanistic studies were initiated to learn how these compounds differ from agents that are being used currently. The concentration of F-Ade, MeP, or 5-fluorouracil required to inhibit CEM cell growth by 50% after a 4-hr incubation was 0.15, 9, or 120 microM, respectively. F-Ade and MeP were also toxic to quiescent MRC-5, CEM, and Balb 3T3 cells. Treatment of CEM, MRC-5, or Balb 3T3 cells with either F-Ade or MeP resulted in the inhibition of protein, RNA, and DNA syntheses. CEM cells converted F-Ade and MeP to F-ATP and MeP-ribonucleoside triphosphate (MeP-R-TP), respectively. The half-life for disappearance of HeP-ribonucleoside triphosphate from CEM cells was approximately 48 hr, whereas the half-lives of F-ATP and ATP were approximately 5 hr. Both MeP and F-Ade were incorporated into the RNA and DNA of CEM cells. These studies indicated that the mechanisms of action of F-Ade and MeP were quite different from those of other anticancer agents, and suggested that the generation of these agents in tumor cells by E. coli PNP could result in significant advantages over those generated by either herpes simplex virus thymidine kinase or E. coli cytosine deaminase. These advantages include a novel mechanism of action resulting in toxicity to nonproliferating and proliferating tumor cells and the high potency of these agents during short-term treatment.     

Increase in plasma leptin and Lep mRNA concentrations by food intake is dependent on insulin

The difference in pregnancy rates following intrauterine insemination (IUI) for 1 vs. 2 days in the periovulatory period has been reported as either inconsequential or favoring the use of two consecutive inseminations, 24 hours apart. Our study compared the monthly fecundity and cumulative probability of pregnancy in a large group of women (n = 123) undergoing controlled ovarian hyperstimulation and 1- or 2-day inseminations with donor sperm prepared from frozen-thawed samples. All patients underwent controlled ovarian hyperstimulation employing either clomiphene citrate in 217 cycles or human menopausal gonadotropin in 185 cycles. The choice of single or double insemination was decided by the day of the week each patient received human chorionic gonadotropin for ovulation induction. Approximately 80% of all the patients underwent both single and double insemination treatments during the 2.5-year study period. Ninety-three patients received single inseminations in 180 cycles, whereas 103 patients received double inseminations in 222 cycles. Nine clinical pregnancies were achieved in the 1-day group (5% per cycle, 9.7% per patient), while 39 pregnancies occurred in the 2-day group (17.9% per cycle, 37.9% per patient). Two and five spontaneous abortions occurred in the 1- and 2-day groups, yielding take-home baby rates of 3.9% per cycle (7.5% per patient) and 15.3% per cycle (33.0% per patient), respectively. The cumulative probability of conception over 15 cycles of treatment was consistently twice as high or higher for the 2-day group. The results of this study support the use of 2-day IUI treatment cycles when using frozen-thawed donor sperm.     

Serum transferrin receptor concentration is not indicative of erythropoietic activity in chronic hemodialysis patients with poor response to recombinant human erythropoietin

BACKGROUND: Serum transferrin receptor (sTfR) is a transmembrane glycoprotein derived from erythroid precursors in the bone marrow. Its concentration provides a quantitative measure of total erythropoietic activity and an indication of functional iron deficiency. This study was conducted to investigate whether sTfR is a useful index of erythropoietic activity in chronic hemodialysis patients with poor response to maintenance recombinant human erythropoietin (rHuEPO) therapy. METHODS: Using an enzyme-linked immunosorbent assay, sTfR concentration was measured in 67 uremic patients who had been on hemodialysis for a mean of 42 months (3-242 months). rHuEPO was administered three times a week to keep the hematocrit above 30%. Hemoglobin, red blood cell indices, serum ferritin, serum total iron binding capacity and unsaturated iron binding capacity were determined. Of the 67 patients, 35 who responded favorably to rHuEPO with hematocrits above 30% were categorized as Group I and 32 who did not attain the target hematocrit were categorized as Group II. As a control group, 31 healthy subjects were also investigated. RESULTS: The serum iron, ferritin, transferrin iron saturation, dialysis efficiency and nutritional state were not different between groups of hemodialysis patients. The mean sTfR concentration was 2.1 +/- 0.6 micrograms/ml (range, 1.15-3.53 micrograms/ml) in Group I patients, compared with 1.9 +/- 0.9 micrograms/ml (range, 1.03-2.65 micrograms/ml) in Group II. The difference was not significant. In addition, the mean sTfR concentration of 1.8 +/- 0.4 micrograms/ml (range, 0.86-2.76 micrograms/ml) in the healthy controls was not significantly different from Groups I and II. CONCLUSIONS: sTfR concentration cannot be used to distinguish good from poor rHuEPO responders among chronic hemodialysis patients who have elevated serum ferritin (> 300 micrograms/l) and transferrin iron saturation (> 25%) during the course of maintenance rHuEPO therapy.     

Alternative locations for internal defibrillator electrodes

Successful defibrillation is described in two patients in whom the defibrillating electrode was positioned in the coronary sinus and right ventricular outflow tract as alternative sites. Internal cardiac defibrillation has been successful with single or multiple endocardial electrodes, epicardial patch electrodes, and subcutaneous surface electrodes (patch, array) in varying combinations and recently with an active can electrode. While the traditional location of the endocardial electrode has been the right ventricular apex, we describe two patients in whom defibrillation was successful in alternate locations, the coronary sinus and the right ventricular outflow tract.     

Why behavior analysts should study emotion: the example of anxiety

Historically, anxiety has been a dominant subject in mainstream psychology but an incidental or even insignificant one in behavior analysis. We discuss several reasons for this discrepancy. We follow with a behavior-analytic conceptualization of anxiety that could just as easily be applied to emotion in general. Its primary points are (a) that languageable humans have an extraordinary capacity to derive relations between events and that it is a simple matter to show that neutral stimuli can acquire discriminative functions indirectly with no direct training; (b) that private events can readily acquire discriminative functions; (c) that anxiety disorders seem to occur with little apparent direct learning or that the amount of direct learning is extraordinarily out of proportion with the amount of responding; and (d) that the primary function of anxious behavior is experiential avoidance. We conclude that the most interesting aspects of anxiety disorders may occur as a function of derived rather than direct relations between public events and overt and private responses with avoidance functions. Implicit in this conclusion and explicit in the paper is the assertion that anxiety is a suitable subject for behavior-analytic study.     

Localized mucosal involvement and severe pulmonary involvement in a young patient with paraneoplastic pemphigus associated with Castleman''s tumour

OBJECTIVES: This study examined the impact of state legislation on mammography quality and access in Michigan. METHODS: The impact of state legislation was analyzed with respect to utilization, numbers of machines and facilities, and image quality. RESULTS: The legislation had a positive effect on image quality improvement, had no impact on utilization by women aged 50 years and above, and resulted in few facility closures. CONCLUSIONS: Michigan's legislative intervention appears to have had a positive effect on efforts to improve mammography quality assurance with implications for other federal and state efforts to achieve quality assurance in health care delivery.