Calmodulin stimulates the degradation of brain spectrin by calpain

Brain spectrin has been shown to be a preferential substrate of calcium-dependent proteases (Baudry, Bundman, Smith, and Lynch: Science 212:937-938, 1981) and a major calmodulin-binding protein (Kakiuchi, Sobue, and Fujita: FEBS Lett. 132:144-148, 1981). Since calmodulin, spectrin, and a proteolytically derived spectrin fragment are all components of isolated postsynaptic density preparations (Grab, Berzins, Cohen, and Siekevitz: J. Biol. Chem. 254:8690-8696, 1979; Carlin, Bartelt, and Siekevitz: J. Cell Biol. 96:443-448, 1983), we investigated the functional role of calmodulin binding to brain spectrin with respect to its susceptibility to digestion by proteases. We report that calmodulin's interaction with brain spectrin results in a marked acceleration of the rate of spectrin degradation by calcium-dependent proteases (calpains I and II), but not by chymotrypsin. The cleavage of erythrocyte spectrin (which lacks a high-affinity calmodulin binding site) by calpain I is unaffected by the presence of calmodulin. The stimulatory effect of calmodulin is blocked by trifluoperazine, a calmodulin antagonist, which by itself does not modify brain spectrin proteolysis by calcium-dependent proteases. These results suggest a novel role for calmodulin in neuronal function--namely, a synergistic interaction with calcium-dependent proteases in the regulation of cytoskeletal integrity.     

Recombinant human interferon alpha increases oestrogen receptor expression in human breast cancer cells (ZR-75-1) and sensitizes them to the anti-proliferative effects of tamoxifen

Exposure of ZR-75-1 human breast cancer cells for 48 h to human recombinant interferon alpha (IFN alpha) resulted in increased expression of oestrogen receptors as measured in a whole cell binding assay. This effect was inversely proportional to dose being significant following treatment with 10-100 IU IFN ml-1 and was only observed at a low initial cell plating density. The extent of the increase in oestrogen receptor levels ranged from 1.2- to 7.2-fold following treatment with 10 IU IFN ml-1. No increase in progesterone receptor expression was observed under the same experimental conditions. Concentrations of IFN which increased oestrogen receptor levels had no effect on cell proliferation. IFN (500 IU ml-1) inhibited cell proliferation and the combination of this treatment with tamoxifen (2 microM) had a greater anti-proliferative effect than either drug alone although there was no evidence of synergism. However, a 5-day pretreatment of cells with IFN (10 IU ml-1) markedly sensitised them to the growth-inhibiting effect of a subsequent 6-day exposure to tamoxifen.     

CNS 7056: A Novel Ultra-short-acting Benzodiazepine

Background: A new benzodiazepine derivative, CNS 7056, has been developed to permit a superior sedative profile to current agents, i.e., more predictable fast onset, short duration of sedative action, and rapid recovery profile. This goal has been achieved by rendering the compound susceptible to metabolism via esterases. The authors now report on the profile of CNS 7056 in vitro and in vivo.

Methods: The affinity of CNS 7056 and its carboxylic acid metabolite, CNS 7054, for benzodiazepine receptors and their selectivity profiles were evaluated using radioligand binding. The activity of CNS 7056 and midazolam at subtypes ([alpha]1[beta]2[gamma]2, [alpha]2[beta]2[gamma]2, [alpha]3[beta]2[gamma]2, [alpha]5[beta]2[gamma]2) of the [gamma]-aminobutyric acid type A (GABAA) receptor was evaluated using the whole cell patch clamp technique. The activity of CNS 7056 at brain benzodiazepine receptors in vivo was measured in rats using extracellular electrophysiology in the substantia nigra pars reticulata. The sedative profile was measured in rodents using the loss of righting reflex test.

Results: CNS 7056 bound to brain benzodiazepine sites with high affinity. The carboxylic acid metabolite, CNS 7054, showed around 300 times lower affinity. CNS 7056 and CNS 7054 (10 [mu]m) showed no affinity for a range of other receptors. CNS 7056 enhanced GABA currents in cells stably transfected with subtypes of the GABAA receptor. CNS 7056, like midazolam and other classic benzodiazepines, did not show clear selectivity between subtypes of the GABAA receptor. CNS 7056 (intravenous) caused a dose-dependent inhibition of substantia nigra pars reticulata neuronal firing and recovery to baseline firing rates was reached rapidly. CNS 7056 (intravenous) induced loss of the righting reflex in rodents. The duration of loss of righting reflex was short (< 10 min) and was inhibited by pretreatment with flumazenil.     

Challenges in accessing multidisciplinary pain treatment facilities in Canada

PURPOSE: The objective of this survey was to examine the services offered by multidisciplinary pain treatment facilities (MPTFs) across Canada and to compare access to care at these MPTFs. METHODS: A MPTF was defined as a clinic that advertised specialized multidisciplinary services for the diagnosis and management of patients with chronic pain, having a minimum of three different health care disciplines (including at least one medical speciality) available and integrated within the facility. The search method included approaching all hospital and rehabilitation centre administrators in Canada, the Insurance Bureau of Canada, the Workplace Safety and Insurance Board or similar body in each province. Designated investigators were responsible for confirming and supplementing MPTFs from the preliminary list for each province. Administrative leads at each eligible MPTF were asked to complete a detailed questionnaire regarding their MPTF infrastructure, clinical, research, teaching and administrative activities. RESULTS: Completed survey forms were received from 102 MPTFs (response rate 85%) with 80% concentrated in major cities, and none in Prince Edward Island and the Territories. The MPTFs offer a wide variety of treatments including non-pharmacological modalities such as interventional, physical and psychological therapy. The median wait time for a first appointment in public MPTFs is six months, which is approximately 12 times longer than non-public MPTFs. Eighteen pain fellowship programs exist in Canadian MPTFs and 64% engage in some form of research activities CONCLUSION: Canadian MPTFs are unable to meet clinical demands of patients suffering from chronic pain, both in terms of regional accessibility and reasonable wait time for patients' first appointment.     

Accurate patient history contributes to differentiating diabetes insipidus: a case study.

This case study highlights the important contribution of nursing in obtaining an accurate health history. The case discussed herein initially appeared to be neurogenic diabetes insipidus (DI) secondary to a traumatic brain injury. The nursing staff, by reviewing the patient's health history with his family, discovered a history of polydipsia and long-standing lithium use. Lithium is implicated in drug-induced nephrogenic DI, and because the patient had not received lithium since being admitted to the hospital, his treatment changed to focus on nephrogenic DI. By combining information from the patient history, the physical examination, and radiologic and laboratory studies, the critical care team demonstrated that the patient had been self-treating his lithium-induced nephrogenic DI and developed neurogenic DI secondary to brain trauma. Thus successful treatment required that nephrogenic and neurogenic DI be treated concomitantly.     

Genotype/phenotype of familial pancreatic cancer.

It is estimated that 5% to 10% of pancreatic cancer cases are attributable to hereditary factors. We believe that the number of cases that are genetic in etiology are even greater, however, based not on a classic autosomal dominant pattern of inheritance but rather when one takes into account low-penetrant inherited susceptibility factors. There is also a growing recognition that the development of pancreatic cancer in pancreatic cancer-prone families is dependent not only on genetic variables but on nongenetic factors. The aim of this article is to review the challenges in identifying pancreatic cancer-prone families and how environmental factors interact with genetic factors in these families.     

GLUT1 and GLUT8 in endometrium and endometrial adenocarcinoma.

Glucose is provided to cells by a family of glucose transport facilitators known as GLUTs. These transporters are expressed in a tissue specific manner and are overexpressed in many primary tumors of these tissues. Regulation of glucose transport facilitator expression has been demonstrated in endometrial tissue and endometrial adenocarcinoma. The following experiments were conducted to quantify and localize the expression of GLUT1 and GLUT8 in benign endometrium and compare this expression to endometrial cancer. Endometrial tissue samples were obtained from random hysterectomy specimens of patients with benign indications for surgery and endometrial cancer. Immunoblot and immunolocatization studies were performed using GLUT1 and GLUT8 specific antisera. Endometrial samples from 65 women who had undergone hysterectomy were examined (n=38 benign, n=27 malignant). A 44 and a 35.4 kDa immunoreacive species was demonstrated in endometrium and endometrial cancer for GLUT1 and GLUT8, respectively. Upregulation of GLUT1 expression was demonstrated with increasing grade of tumors (P<0.002). GLUT8 expression was increased in all tumor subtypes compared to atrophic endometrium (P<0.001). Apical localization by GLUT1 and GLUT8 was demonstrated in endometrial glands. GLUT1 and GLUT8 demonstrated diffuse intracellular localization in the cancer subtypes. GLUT1 and GLUT8 are expressed in both human endometrium and endometrial cancer. There appears to be a step-wise progression in GLUT1 and GLUT8 expression as tumor histopathology worsens. GLUT1 and GLUT8 may be important markers in tumor differentiation, as well as providing energy to rapidly dividing tumor cells.