Physician-Patient Communication Course: When the Inauguration of a New Israeli Medical School Coincided with COVID-19 Pandemic

Purpose

The curriculum of the Adelson School of Medicine at Ariel University, the newly established sixth medical school in Israel, includes a simulation center-based extended course on physician-patient communication, aiming to help students master the core competency of interpersonal and communication skills. For more than a year following the emergence of the COVID-19 pandemic, the school suspended most face-to-face (F2F) encounters, transforming most teaching activities to remote platforms. The paper outlines the ways we adapted teaching of this course to these circumstances, the reactions of students and mentors to the changes and results of 1st year students' survey.

Methods

During the lockdown in the first year 48 of 70 first-year students participated in a voluntary anonymous online evaluation of the course assessing motivation to become a physician; perceptions, feelings and attitudes towards the communication course, and advantages and disadvantages of online and F2F medical interviews.

Results

46.1% of the responding students reported that the pandemic strengthened their desire to become physicians. 56.3% claimed that they were able to a relatively large extent to empathize with COVID-19 patients who were exposed to the virus; 79.1% viewed their mentors as positive role models of communication skills. The students were able to receive and offer social support to their peers. They evaluated very highly the short instructional videos produced by the faculty.

Conclusion

During the lockdown, the respondents generally indicated positive attitudes towards the communication course, the mentors and the inclusion of physician-patient communication as a topic in medical education. The students and mentors reported many disadvantages and few advantages of remote learning. Yet inevitably remote learning including online-based simulations is a step towards preparations for future practice within virtual medical care and telemedicine. The limitations of this study include the cross-sectional design, small sample size and self-reporting.

Probing the self-assembly and anti-glioblastoma efficacy of a cinnamoyl-capped dipeptide hydrogelator

Herein, we introduce the first diphenylalanine dipeptide hydrogelator capped with the cinnamoyl functional group (Cin-L-F-L-F). We evaluate the effects of the cinnamoyl moiety on molecular self-assembly events and resultant physical properties of the hydrogel formed. In addition, we report our preliminary results of this dipeptide's cytotoxicity against glioblastoma (GBM) cancer cells.

P13.10 Chemoattraction of glioma cells in a local hydrogel trap and immune control associated with improved survival and cognitive functions in a mouse model of glioblastoma resection

BACKGROUND

Glioblastoma (GB) is the most aggressive brain primary tumor. The prognosis remains poor mainly due to the invasiveness of glioma cells, radio and/or chemoresistance and GB-induced immunosuppressive environment. Here, we propose to use a local delivery system based on a biocompatible hydrogel containing the chemopeptide urotensin II (hUII) or a biased synthetic analog DAB8-hUII, to “trap” GB cells, and/or to control immune cells expressing its G protein-coupled receptor UT, leading to tumor regression and neurological benefit, in a mouse model of GB resection.

MATERIAL AND METHODS

In vitro, invasion towards UII/analog across different hydrogels or glue of human or murine GB-GFP cell lines was evaluated in Boyden chamber and cloning ring assays. In vivo GB cells were intrastriatally xenografted, then resected while hydrogel- or glue-containing UII/analog was injected in the cavity resection. Behavioral tests, brain immunohistochemical analyses and mouse survival were then investigated.

RESULTS

In vitro, invasive capacity of human U87 and 42MG or murine GL261 and CT2A GB cells was stimulated by UII loaded into hydrogel-based hyaluronic acid supplemented with collagen or other chemicals, PNIPAAm-PEG, or thrombin-fibrin glue. In vivo, injection of UII- or DAB8-hUII-loaded glue into the cavity resection of GL261 and CT2A GB in C57BL/6 mice significantly improved survival compared with tumor and resected experimental conditions. Neurological status was also tested before and after GB resection. We found that GL261 and CT2A cell-bearing mice expressed altered spontaneous activity, emotion and cognitive functions. Intracavity injection of the glue improved resignation and anxiety and increased motor activity and cognition with a best cognitive recovery with hUII and DAB-8-hUII-loaded glue groups. Ex vivo brain analyses revealed high expression of UT and UII in some GB GFP-positive cells and macrophages within GB core and at the interface with the normal brain, GB cells expressing UT migrating along tortuous podocalyxin+ vascular components. In brains bearing hydrogel/hUII glue, vascularization appears modified and GFAP+ astrocytes and F4/80+ macrophages were highly recruited in the border of the cavity, compared with the other conditions.

CONCLUSION

A local glue containing UII may trap GB cells and remodel the tumor microenvironment responsible for survival and cognitive improvements, providing new option in the therapeutic arsenal of GB.

Cancer-related cognitive impairment: an update on state of the art, detection, and management strategies in cancer survivors

BACKGROUND

Advances in diagnostic and therapeutic strategies in oncology have significantly increased the chance of survival of cancer patients, even those with metastatic disease. However, cancer-related cognitive impairment (CRCI) is frequently reported in patients treated for non-central nervous system cancers, particularly during and after chemotherapy.

DESIGN

This review provides an update of the state of the art based on PubMed searches between 2012 and March 2019 on 'cognition', 'cancer', 'antineoplastic agents' or 'chemotherapy'. It includes the most recent clinical, imaging and pre-clinical data and reports management strategies of CRCI.

RESULTS

Evidence obtained primarily from studies on breast cancer patients highlight memory, processing speed, attention and executive functions as the most cognitive domains impaired post-chemotherapy. Recent investigations established that other cancer treatments, such as hormone therapies and targeted therapies, can also induce cognitive deficits. Knowledge regarding predisposing factors, biological markers or brain functions associated with CRCI has improved. Factors such as age and genetic polymorphisms of apolipoprotein E, catechol-O-methyltransferase and BDNF may predispose individuals to a higher risk of cognitive impairment. Poor performance on neuropsychological tests were associated with volume reduction in grey matter, less connectivity and activation after chemotherapy. In animals, hippocampus-based memory and executive functions, mediated by the frontal lobes, were shown to be particularly susceptible to the effects of chemotherapy. It involves altered neurogenesis, mitochondrial dysfunction or brain cytokine response. An important next step is to identify strategies for managing cognitive difficulties, with primary studies to assess cognitive training and physical exercise regimens.

CONCLUSIONS

CRCI is not limited to chemotherapy. A multidisciplinary approach has improved our knowledge of the complex mechanisms involved. Nowadays, studies evaluating cognitive rehabilitation programmes are encouraged to help patients cope with cognitive difficulties and improve quality of life during and after cancer.

Anesthetic drugs modulate feeding behavior and hypothalamic expression of the POMC polypeptide precursor and the NPY neuropeptide

Background

Several hypnotic drugs have been previously identified as modulators of food intake, but exact mechanisms remain unknown. Feeding behavior implicates several neuronal populations in the hypothalamic arcuate nucleus including orexigenic neuropeptide Y and anorexigenic pro-opiomelanocortin producing neurons. The aim of this study was to investigate in mice the impact of different hypnotic drugs on food consumption and neuropeptide Y or pro-opiomelanocortine mRNA expression level in the hypothalamic arcuate nucleus.

Methods

Saline control, isoflurane, thiopental, midazolam or propofol were administered to C57Bl/6 mice. Feeding behavior was evaluated during 6 h. In situ hybridization of neuropeptide Y and pro-opiomelanocortine mRNAs in the hypothalamus brain region was also performed. Data were analyzed by Kruskal Wallis test and analysis of variance (p < 0.05).

Results

Midazolam, thiopental and propofol induced feeding behavior. Midazolam and thiopental increased neuropeptide Y mRNA level (respectively by 106 and 125%, p < 0.001) compared with control. Propofol and midazolam decreased pro-opiomelanocortine mRNA level by 31% (p < 0,01) compared with control. Isoflurane increased pro-opiomelanocortine mRNA level by 40% compared with control.

Conclusion

In our murine model, most hypnotics induced food consumption. The hypnotic-induced regulation of neuropeptide Y and pro-opiomelanocortine hypothalamic peptides is associated with this finding. Our data suggest that administration of some hypnotic drugs may affect hypothalamic peptide precursor and neuropeptide expression and concomittantly modulate food intake. Thus, this questions the choice of anesthetics for better care management of patients undergoing major surgery or at risk of undernutrition.

Electronic supplementary material

The online version of this article (10.1186/s12871-018-0557-x) contains supplementary material, which is available to authorized users.

Neurodevelopmental long-term outcome in children with hydrocephalus requiring neonatal surgical treatment

PURPOSE

To assess long-term neurodevelopmental outcome in children with hydrocephalus requiring neurosurgical treatment during the neonatal period.

METHODS

This prospective longitudinal population-based study included 43 children with neonatal shunted hydrocephalus. The 43 children were prospectively reviewed in the presence of their parents at the outpatient clinic. Cognitive and motor outcomes were assessed respectively using different Wechsler scales according to age and Gross Motor Function Classification System (GMFCS). Postoperative MRI was routinely performed.

RESULTS

The mean gestational age at birth of the 43 consecutive children with neonatal hydrocephalus (sex ratio M/F: 1.39) was 34.5±5.4 weeks of gestation. At mean follow-up of 10.4±4 years, mean total IQ was 73±27.7, with equivalent results in mean verbal and mean performance IQ. Of the 33 children with IQ evaluation, 18 presented an IQ≥85 (41.9%). Efficiency in walking without a mobility device (GMFCS≤2) was obtained in 37 children (86%). Only severity of postoperative ventricular dilation was significantly associated with unfavorable outcome (Evans index>0.37; odds ratio: 0.16, P=0.03).

CONCLUSION

This information could be provided to those families concerned who often experience anxiety when multi-disciplinary management of neonatal hydrocephalus is required.

Signaling switch of the urotensin II vasosactive peptide GPCR: prototypic chemotaxic mechanism in glioma

Multiform glioblastomas (GBM) are the most frequent and aggressive primary brain tumors in adults. The poor prognosis is due to neo-angiogenesis and cellular invasion, processes that require complex chemotaxic mechanisms involving motility, migration and adhesion. Understanding these different cellular events implies identifying receptors and transduction pathways that lead to and promote either migration or adhesion. Here we establish that glioma express the vasoactive peptide urotensin II (UII) and its receptor UT and that UT-mediated signaling cascades are involved in glioma cell migration and adhesion. Components of the urotensinergic systems, UII and UT, are widely expressed in patient-derived GBM tissue sections, glioma cell lines and fresh biopsy explants. Interestingly, gradient concentrations of UII produced chemoattracting migratory/motility effects in glioma as well as HEK293 cells expressing human UT. These effects mainly involved the G13/Rho/rho kinase pathway while partially requiring Gi/o/PI3K components. In contrast, we observed that homogeneous concentrations of UII drastically blocked cell motility and stimulated cell-matrix adhesions through a UT/Gi/o signaling cascade, partially involving phosphatidylinositol-3 kinase. Finally, we provide evidence that, in glioma cells, homogeneous concentration of UII allowed translocation of Gα13 to the UT receptor at the plasma membrane and increased actin stress fibers, lamellipodia formation and vinculin-stained focal adhesions. UII also provoked a re-localization of UT precoupled to Gαi in filipodia and initiated integrin-stained focal points. Altogether, these findings suggest that UT behaves as a chemotaxic receptor, relaying a signaling switch between directional migration and cell adhesion under gradient or homogeneous concentrations, thereby redefining sequential mechanisms affecting tumor cells during glioma invasion. Taken together, our results allow us to propose a model in order to improve the design of compounds that demonstrate signaling bias for therapies that target specifically the Gi/o signaling pathway.

[Interaction between hypnotic agents and the hypothalamic-pituitary-adrenocorticotropic axis during surgery]

During stress, the relationship between the central nervous system and the immune system is essential to maintain homeostasis. The main neuroendocrine system involved in this interaction is the hypothalamic-pituitary-adrenal axis (HPA), which via the synthesis of glucocorticoids will modulate the intensity of the inflammatory response. Anaesthetic agents could be interacting with the HPA axis during surgery. Although etomidate currently remains in the center of the discussions, it seems, at least experimentally, that most hypnotics have the capacity to modulate the synthesis of adrenal steroids. Nevertheless, with the large literature on this subject, etomidate seems to be the most deleterious hypnotic agent on the HPA axis function. Its use should be limited when HPA axis is already altered.

Hypothalamic glucose-sensing: role of Glia-to-neuron signaling

The hypothalamus senses hormones and nutrients in order to regulate energy balance. In particular, detection of hypothalamic glucose levels has been shown to regulate both feeding behavior and peripheral glucose homeostasis, and impairment of this regulatory system is believed to be involved in the development of obesity and diabetes. Several data clearly demonstrate that glial cells are key elements in the perception of glucose, constituting with neurons a "glucose-sensing unit". Characterization of this interplay between glia and neurons represents an exciting challenge, and will undoubtedly contribute to identify new candidates for therapeutic intervention. The purpose of this review is to summarize the current data that stress the importance of glia in central glucose-sensing. The nature of the glia-to-neuron signaling is discussed, with a special focus on the endozepine ODN, a potent anorexigenic peptide that is highly expressed in hypothalamic glia.

Giant intracranial aneurysms in the paediatric population: Suggested management and a review of the literature

OBJECTIVES

Intracranial aneurysms are rare in children although giant aneurysms more commonly occur in adolescence. The aims of our study were to perform an extensive review of the literature over the past two decades and assess intracranial aneurysm management.

METHODS

Based on a Pubmed search, we carried out a review of the literature from 1990 to 2012 regarding giant intracranial aneurysms diagnosed in the paediatric population. This descriptive study concerned clinical presentation, cerebral aneurysm characteristics, therapeutic management procedures and outcome.

RESULTS

Forty-six cases were reported in 31 papers. The male/female sex ratio was 1.15, the clinical presentation was a tumour mass syndrome in 56.6%, followed by rupture in 30.4%. The aneurysm location was the posterior circulation in 41.3%, and microsurgical treatment (52.2%) predominated over endovascular coiling (28.3%).

CONCLUSION

To date, no evidence-based medicine recommendation has been accepted for the management of rare intracranial aneurysms. Each reported patient was the object of a multidisciplinary clinical decision. Management of this challenging pathology should be performed on a case-to-case basis.

Evolution of class A G-protein-coupled receptors: implications for molecular modeling

Class A or rhodopsin-like G-protein-coupled receptors (GPCRs) constitute the largest transmembrane receptor family of the human genome. Because of their biological and pharmaceutical importance, the evolutionary history of these receptors has been widely studied. Most studies agree on the classification of the 700 members of this family into a dozen of sub-families. However, the relationship between these sub-families remains controversial and the molecular processes that drove the evolution and diversification of such a large family have still to be determined. We review here the evolutionary analyses carried out on class A GPCRs either by phylogenetic methods or by multidimensional scaling (MDS). We detail the key molecular events driving the evolution of this receptor family. We analyze these events in view of the recently resolved crystal structures of GPCRs and we discuss the usefulness of evolutionary information to help molecular modeling.

Elderly patients with aneurysmal subarachnoid hemorrhage: Coils but also clips

The ageing of the population in good health or without severe morbidity expose them to the occurrence of a subarachnoid hemorrhage (SAH) and requires effective management. Currently, the pertinence of cerebral aneurysm treatment by clipping or coiling is accepted for patients in the 8th or 9th decade of life, and the risk of postoperative morbidity induced by our therapeutic alternative must be carefully assessed. In these decades, the female/male sex ratio for aneurysmal SAH was greater in female who had a 1.6 times higher ratio than in male. The initial clinical status did not appear worse with age despite the frequent severity of bleeding observed on CT scan probably due to the large subarachnoid space. The aneurysm distribution and size were similar to those classically reported in the global population. The endovascular (EV) coiling appears as the first option with a favorable outcome rate estimated at 48% to 63%. Nevertheless, the benefit of EV coiling compared to microsurgical clipping for treatment of ruptured aneurysm in the elderly has not been demonstrated in a large randomized study. This is the reason why the vascular section of the French Society of Neurosurgery developed a prospective and randomized study of the aneurysmal SAH (PHRC 2007-042/HP) on the elderly patients.

Psychosocial abilities of first-year medical students participating in a clinical communication course

BACKGROUND

Responding to psychosocial needs of patients is an important element of medical practice and is dependent on the psychosocial abilities of the physician. One of the aims of teaching doctor-patient communication in medical schools is to strengthen these qualities. We assessed changes in the psychosocial abilities of first-year medical students participating in a year-long clinical communication course.

METHODS

Sixty-eight first-year medical students and 49 students from the Medical Laboratories School (control group) participated in the study. The students completed, once each at the beginning (October) and at the end (July) of the course, a structured questionnaire that included a psychosocial abilities measure and sociodemographic details.

RESULTS

No significant differences were found between the two groups of students regarding their sociodemographic characteristics. Furthermore, the medical students and the control group did not differ significantly in their psychosocial abilities mean scores at the beginning of the communication course (baseline). At the end of the course, a significant improvement in mean scores was found among medical students compared with an insignificant decline among the control group.

CONCLUSION

Participation in an extensive clinical doctor-patient communication course guided by multidisciplinary teams may strengthen psychosocial abilities of medical students. The study needs to be replicated with a larger sample size.

Anti-viral therapy in haemodialysed HCV patients: efficacy, tolerance and treatment strategy

BACKGROUND

In end-stage renal disease (ESRD) patients, hepatitis C virus (HCV) eradication improves patient and graft survival.

AIM

To determine optimal use of erythropoietin (EPO) and ribavirin, to compare ribavirin concentrations with those of HCV patients having normal renal function and to evaluate sustained virological response (SVR) in a prospective observatory of ESRD candidates for renal transplantation.

METHODS

Thirty-two naïve patients were treated with Peg-IFN-α2a and ribavirin. Two different schedules of ribavirin and EPO administration were used: starting ribavirin at 600mg per week and adapting EPO when haemoglobin (Hb) fell below 10g/dL (adaptive strategy) or starting ribavirin at 1000mg per week while increasing EPO from the start of treatment (preventive strategy).

RESULTS

Patients treated with the adaptive strategy had lower median Hb levels (9.6 vs. 10.9g/dL, P=0.02) and more frequent median Hb levels below 10g/dL (58 vs. 5%, P=0.0007) despite lower median ribavirin doses (105 vs. 142mg/day, P<0.0001) than patients treated with the preventive strategy. There was a trend for more frequent transfusion in patients treated with the adaptive strategy than in patients treated with preventive strategy (50 vs. 20%, P=0.08). Compared to patients with normal renal function, ESRD patients had lower ribavirin concentrations during the first month (0.81 vs. 1.7mg/L, P=0.007) and similar concentrations thereafter. SVR was reached in 50%.

CONCLUSIONS

Pegylated interferon (Peg-IFN) and an adapted schedule of ribavirin are effective in ESRD patients. Increasing EPO from the start of treatment provides better haematological tolerance. The optimal dosage of ribavirin remains unresolved, in light of frequent side effects.

Acute food deprivation reduces expression of diazepam-binding inhibitor, the precursor of the anorexigenic octadecaneuropeptide ODN, in mouse glial cells

In the central nervous system of mammals, the gene encoding diazepam-binding inhibitor (DBI) is exclusively expressed in glial cells. Previous studies have shown that central administration of a DBI processing product, the octadecaneuropeptide ODN, causes a marked inhibition of food consumption in rodents. Paradoxically, however, the effect of food restriction on DBI gene expression has never been investigated. Here, we show that in mice, acute fasting dramatically reduces DBI mRNA levels in the hypothalamus and the ependyma bordering the third and lateral ventricles. I.p. injection of insulin, but not of leptin, selectively stimulated DBI expression in the lateral ventricle area. These data support the notion that glial cells, through the production of endozepines, may relay peripheral signals to neurons involved in the central regulation of energy homeostasis.

Further confirmation of the psychometric properties of responses to the psychological medicine inventory -student version

CONTEXT

The Psychological Medicine Inventory (PMI) was first developed to measure physicians' reported interest level, confidence and perceived ability to address the psychological aspects of patient care. A student version of this scale has since been proposed (PMI-S).

OBJECTIVE

To further examine the psychometric properties of responses to this student version and to confirm a 2-factor response structure.

METHODS

A total of 213 first-year medical students at Ben-Gurion University of the Negev participated in this study. They completed the PMI-S (translated into Hebrew) and a socio-demographic questionnaire. The viability of the 2-factor structure of PMI-S responses was assessed using confirmatory factor analysis (CFA).

FINDINGS

Consistent with the original English language version, CFA supported a 2-factor solution (i.e., psychological abilities and psychological sensitivity). All goodness-of-fit indices were found to be within ideal parameters.

DISCUSSION AND CONCLUSIONS

Results of this study suggest that the PMI-S can be used to assess psychosocial competence and abilities of medical students and to evaluate the effectiveness of psycho-educational programs aimed at improving their psychosocial abilities.

Improved survival after liver transplantation in patients with hepatopulmonary syndrome

Hepatopulmonary syndrome (HPS) is present in 10-32% of chronic liver disease patients, carries a poor prognosis and is treatable by liver transplantation (LT). Previous reports have shown high LT mortality in HPS and severe HPS (arterial oxygen (PaO(2)) < or =50 mmHg). We reviewed outcomes in HPS patients who received LT between 2002 and 2008 at two transplant centers supported by a dedicated HPS clinic. We assessed mortality, complications and gas exchange in 21 HPS patients (mean age 51 years, MELD score 14), including 11/21 (52%) with severe HPS and 5/21 (24%) with living donor LT (median follow-up 20.2 months after LT). Overall mortality was 1/21 (5%); mortality in severe HPS was 1/11 (9%). Peritransplant hypoxemic respiratory failure occurred in 5/21 (24%), biliary complications in 8/21 (38%) and bleeding or vascular complications in 6/21 (29%). Oxygenation improved in all 19 patients in whom PaO(2) or SaO(2) were recorded. PaO(2) increased from 52.2 +/- 13.2 to 90.3 +/- 11.5 mmHg (room air) (p < 0.0001) (12 patients); a higher baseline macroaggregated albumin shunt fraction predicted a lower rate of postoperative improvement (p = 0.045) (7 patients). Liver transplant survival in HPS and severe HPS was higher than previously demonstrated. Severity of HPS should not be the basis for transplant refusal.

Acquired chromosome instability in the elderly--the effect of diepoxybutane

Aging and Alzheimer's disease (AD) have been the subject of many studies. It has been suggested that chromosomal alterations may be involved in the etiology and/or pathogenesis of ageing and AD. The purpose of the present study was to examine the effect of diepoxybutane (DEB) on lymphocyte chromosomal instability in the elderly. We examined lymphocytes cytogenetically with, as well as, without DEB treatment, in a group of 12 elderly (range of age 72-96 years), nine of them suffering from AD type. Without DEB treatment six of the donors expressed chromosomal instability in at least 6% of the analyzed cells. After treatment with DEB, lymphocytes showed an increase in the chromosomal instability in up to 20% of the analyzed in eight donors. The sex chromosomes were the main chromosomes involved in the acquired chromosomal abnormalities. It is not clear from this study whether this chromosomal instability is related to the AD. The significance of the involvement of sex chromosomes either in ageing or in AD, as well as, the question whether the chromosomal instability is the cause of or part of ageing processes, has to be addressed.

Depressive symptoms and risk for malnutrition among hospitalized elderly people

OBJECTIVES

To explore the association between depressive symptoms and risk for malnutrition in hospitalized elderly people.

METHODS

195 hospitalized medical patients older than 65 years of age were studied in a cross-sectional design. Depression was assessed by 30-item Geriatric Depression Scale (GDS), nutritional status was evaluated by the Mini-Nutritional Assessment (MNA). Eating and digestive problems were assessed using selected items of Nutrition Risk Index (NRI), cognitive and functional status by Folstein and Barthel indices respectively; demographic data, diagnoses and medications were obtained from medical records.

RESULTS

The prevalence of depression in the studied population was 28%. MNA scores were significantly lower among depressed patients as compared with non-depressed (22.86 vs. 24.96, p < 0.001), indicating a higher risk for undernutrition among depressed persons. After controlling for age, cognitive status, functional ability, and number of illnesses, undernutrition was significantly associated with depression (OR = 2.23; 95% CI: 1.04-4.8).

CONCLUSIONS

Nutritional risk is associated with depression in aged inpatients. Close case management of the elderly hospitalized patients that include assessment and treatment for both disorders may be beneficial.

Examination of a modified version of the Psychological Medical Inventory among medical students

BACKGROUND

The Psychological Medical Inventory (PMI) assesses the level of interest, confidence, and perceived clinical abilities in addressing psychological aspects of patient care. The scale has been used solely among physicians and other healthcare professionals.

AIMS

To examine the psychometric properties and factor structure of a modified student version (PMI-S) of the PMI among medical students.

METHOD

Sixty eight freshmen medical students completed a self-reporting questionnaire that included the PMI-S scale and a measure of perceived overall communication abilities.

RESULTS

Consistent with the original scale, the factor analysis yielded a two-factor solution-psychological abilities and psychological sensitivity. The modified scale also demonstrated a high percentage of explained variance. Additionally, positive correlations were found between students' ratings of their perceived psychological abilities, psychological sensitivity, total scale score, and overall communication abilities.

CONCLUSIONS

The results support the factor structure of the original scale. The PMI-S scale might be incorporated in the evaluation of the effectiveness of psycho-educational programs and interventions aimed at improving the psychosocial abilities of students of medicine and health professions. Further examination of the scale with a larger sample size is needed.

Characteristics of undernourished older medical patients and the identification of predictors for undernutrition status

Background

Undernutrition among older people is a continuing source of concern, particularly among acutely hospitalized patients. The purpose of the current study is to compare malnourished elderly patients with those at nutritional risk and identify factors contributing to the variability between the groups.

Methods

The study was carried out at the Soroka University Medical Center in the south of Israel. From September 2003 through December 2004, all patients 65 years-of-age or older admitted to any of the internal medicine departments, were screened within 72 hours of admission to determine nutritional status using the short version of the Mini Nutritional Assessment (MNA-SF). Patients at nutritional risk were entered the study and were divided into malnourished or 'at risk' based on the full version of the MNA. Data regarding medical, nutritional, functional, and emotional status were obtained by trained interviewers.

Results

Two hundred fifty-nine elderly patients, 43.6% men, participated in the study; 18.5% were identified as malnourished and 81.5% were at risk for malnutrition according to the MNA. The malnourished group was less educated, had a higher depression score and lower cognitive and physical functioning. Higher prevalence of chewing problems, nausea, and vomiting was detected among malnourished patients. There was no difference between the groups in health status indicators except for subjective health evaluation which was poorer among the malnourished group. Lower dietary score indicating lower intake of vegetables fruits and fluid, poor appetite and difficulties in eating distinguished between malnourished and at-risk populations with the highest sensitivity and specificity as compare with the anthropometric, global, and self-assessment of nutritional status parts of the MNA. In a multivariate analysis, lower cognitive function, education <12 years and chewing problems were all risk factors for malnutrition.

Conclusion

Our study indicates that low food consumption as well as poor appetite and chewing problems are associated with the development of malnutrition. Given the critical importance of nutritional status in the hospitalized elderly, further intervention trials are required to determine the best intervention strategies to overcome these problems.

Mixing of nasopharyngeal and oropharyngeal samples to identify potential respiratory pathogens in adults

A mixed culture of oropharyngeal swabs, nasopharyngeal swabs and nasopharyngeal washings, taken from 400 patients, was compared to separate cultures of the same samples. The mixed culture identified Streptococcus pneumoniae in 37 of 40 (93%) patients with positive samples, Hemophilus influenzae in 28 of 29 (97%), and Moraxella catarrhalis in 94 of 94 (100%). These sensitivity rates clearly justify the use of mixed cultures instead of separate cultures for clinical and epidemiological purposes. The reduction in costs stemming from the use of mixed cultures may have a decisive influence when considering this test for extensive clinical and epidemiological purposes.

Naso- and oropharyngeal potential respiratory pathogens in adults with nonpneumonic lower respiratory tract infection

The objective of this prospective study was to determine positive isolation rates for potential respiratory pathogens (PRPs) in the naso- and oropharynx of adults hospitalized for nonpneumonic lower respiratory tract infection (NPLRTI), compared with patients with community-acquired pneumonia (CAP) and healthy controls. The study population was 315 non-chronic obstructive pulmonary disease adults hospitalized with febrile lower respiratory tract infection (158 NPLRTI and 157 CAP) and 450 control subjects. Each participant was sampled by oropharyngeal swab, nasopharyngeal swab, and nasopharyngeal washings that were tested by conventional bacteriologic methods to identify PRP. At least 1 of the samples was positive for at least 1 of the 3 PRP bacteria in 55 NPLRTI patients (35%) compared with 51 CAP patients (33%) (NS) and 100 controls (22%) (P = 0.003 compared with NPLRTI and P = 0.02 compared with CAP). Samples were positive for Streptococcus pneumoniae in 14 NPLRTI patients (9%) compared with 29 CAP patients (19%) (P = 0.02) and 16 controls (4%) (NPLRTI P = 0.015, CAP P < 0.0001). The corresponding rates for Haemophilus influenzae were 23 (15%), 16 (10%), and 60 (13%) (NS for all 3 comparisons), and for Moraxella catarrhalis, 28 (18%), 25 (16%), and 48 (11%), respectively (NPLRTI versus controls, P = 0.03, NS other comparisons). We conclude that the rate of positive naso/oropharyngeal isolates for at least 1 of the 3 PRP bacteria in NPLRTI patients is similar to the corresponding rates for CAP patients and is higher in both groups than in controls.

Gender differences in factors associated with nutritional status of older medical patients

OBJECTIVES

To evaluate gender differences in nutritional risk of older people admitted to an acute-care general medical department, and identify gender-specific risk factors.

DESIGN

Cross-sectional study.

SETTING

Internal Medicine Department in an acute care, university-affiliated hospital in southern Israel.

SUBJECTS

204 cognitively intact patients aged 65 and over, admitted during a 12-month period to a general medical department.

MEASURES OF OUTCOME

Evaluation included demographic and clinical data consisting of the sum of medical conditions and of prescribed medications, evaluation of nutritional status, cognitive status, depression assessment and functional ability. Statistical analyses were conducted to evaluate the gender specific risk factors for under-nutrition.

RESULTS

32.5% of the men and 48.1% of the women admitted to an internal medicine department were at risk for under-nutrition. Those at nutritional risk had a higher rate of depression, lower cognitive and physical ability, poorer reported health status and more diagnosed diseases. Nutritional risk for men was associated with higher depression score, longer hospitalization, and poor appetite. For women, nutritional risk was associated with lower functional status and more diagnosed diseases. In a multivariate analysis, being a female increased the risk of under-nutrition by 3.3 fold.

CONCLUSION

Risk of under-nutrition is prevalent among older in-patients and is gender-related. Female inpatients are at markedly increased risk for under-nutrition. The mechanism of the gender discrepancy in factors related to nutritional deterioration is complex and poorly understood.

Nasopharyngeal versus oropharyngeal sampling for isolation of potential respiratory pathogens in adults

The optimal methodology for the identification of colonization by potential respiratory pathogens (PRP) in adults is not well established. The objectives of the present study were to compare the sensitivities of sampling the nasopharynx and the oropharynx for identification of PRP colonization and to compare the sensitivities of samples from the nasopharynx by swab and by washing for the same purpose. The study included 500 participants with a mean age of 65.1 +/- 17.8 years. Of these, 300 patients were hospitalized for acute febrile lower respiratory tract infection and 200 were controls. Each participant was sampled by oropharyngeal swab (OPS), nasopharyngeal swab (NPS), and nasopharyngeal washing (NPW). The samples were tested by conventional bacteriological methods to identify Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. OPS detected colonization by S. pneumoniae in 30% of the subjects compared with 89% by NPS and NPW (P < 0.000001). The corresponding rates for H. influenzae were 49% and 64%, respectively (no significant difference [NS]), and for M. catarrhalis were 72% and 46%, respectively (P < 0.0004). NPS identified 61% of the cases of colonization with S. pneumoniae, compared with 76% by NPW (NS). The corresponding rates for H. influenzae were 31% and 56%, respectively (P < 0.04), and for M. catarrhalis were 39% and 33%, respectively (NS). We conclude that the sensitivities of nasopharyngeal and oropharyngeal sampling for identification of PRP colonization in adults are different for each of the three bacteria in this category. The combined results of sampling from both sites are necessary to obtain a true picture of the rate of colonization. NPW is superior to NPS.

Marked secular increase in the incidence rates of osteoporotic hip fractures in women and men in southern Israel

BACKGROUND

For the last 35 years, our medical center has been the only referral center and provider of emergency medical services for a well-defined geographic area in southern Israel.

OBJECTIVES

To evaluate trends in the incidence of hip fractures in this population.

METHODS

The study was based on two surveys done approximately 20 years apart. It included women and men 50 years and older with radiographic evidence of a new hip fracture caused by low impact trauma. Only fractures that resulted from low or moderate trauma were considered for the current study. Incidence rates were calculated based on population data obtained from the official Central Bureau of Statistics.

RESULTS

There was an overall twofold increase in the incidence rate of hip fractures. However, this increase occurred almost exclusively in the over-75 year old age groups (2.5-fold increase, both in women and men). The mean (and median) age of patients with hip fractures increased significantly over the study period, corresponding to the increase in longevity between the two periods.

CONCLUSIONS

There was a marked secular increase in the incidence of proximal hip fractures in both genders, primarily because of an increase in the fracture rate in the very old. The increase in median age of fracture patients suggests that the observed increase in fracture rate can be attributed mainly to aging of the population rather than to deterioration in bone quality over the generations.

PACAP inhibits delayed rectifier potassium current via a cAMP/PKA transduction pathway: evidence for the involvement of I k in the anti-apoptotic action of PACAP

Abstract Activation of potassium (K(+)) currents plays a critical role in the control of programmed cell death. Because pituitary adenylate cyclase-activating polypeptide (PACAP) has been shown to inhibit the apoptotic cascade in the cerebellar cortex during development, we have investigated the effect of PACAP on K(+) currents in cultured cerebellar granule cells using the patch-clamp technique in the whole-cell configuration. Two types of outward K(+) currents, a transient K(+) current (I(A)) and a delayed rectifier K(+) current (I(K)) were characterized using two different voltage protocols and specific inhibitors of K(+) channels. Application of PACAP induced a reversible reduction of the I(K) amplitude, but did not affect I(A), while the PACAP-related peptide vasoactive intestinal polypeptide had no effect on either types of K(+) currents. Repeated applications of PACAP induced gradual attenuation of the electrophysiological response. In the presence of guanosine 5'-[gammathio]triphosphate (GTPgammaS), PACAP provoked a marked and irreversible I(K) depression, whereas cell dialysis with guanosine 5'-[betathio]diphosphate GDPbetaS totally abolished the effect of PACAP. Pre-treatment of the cells with pertussis toxin did not modify the effect of PACAP on I(K). In contrast, cholera toxin suppressed the PACAP-induced inhibition of I(K). Exposure of granule cells to dibutyryl cyclic adenosine monophosphate (dbcAMP) mimicked the inhibitory effect of PACAP on I(K). Addition of the specific protein kinase A inhibitor H89 in the patch pipette solution prevented the reduction of I(K) induced by both PACAP and dbcAMP. PACAP provoked a sustained increase of the resting membrane potential in cerebellar granule cells cultured either in high or low KCl-containing medium, and this long-term depolarizing effect of PACAP was mimicked by the I(K) specific blocker tetraethylammonium chloride (TEA). In addition, pre-incubation of granule cells with TEA suppressed the effect of PACAP on resting membrane potential. TEA mimicked the neuroprotective effect of PACAP against ethanol-induced apoptotic cell death, and the increase of caspase-3 activity observed after exposure of granule cells to ethanol was also significantly inhibited by TEA. Taken together, the present results demonstrate that, in rat cerebellar granule cells, PACAP reduces the delayed outward rectifier K(+) current by activating a type 1 PACAP (PAC1) receptor coupled to the adenylyl cyclase/protein kinase A pathway through a cholera toxin-sensitive Gs protein. Our data also show that PACAP and TEA induce long-term depolarization of the resting membrane potential, promote cell survival and inhibit caspase-3 activity, suggesting that PACAP-evoked inhibition of I(K) contributes to the anti-apoptotic effect of the peptide on cerebellar granule cells.

Hypovitaminosis D among inpatients in a sunny country

BACKGROUND

Hypovitaminosis D is an important risk factor for osteoporosis and its complications. Previous studies found that the incidence of hypovitaminosis D among patients in an internal medicine ward reached up to 57%.

OBJECTIVE

To determine the prevalence and determinants of hypovitaminosis D among patients in internal medicine wards in a sunny country.

METHODS

We measured 25-hydroxyvitamin D, parathyroid hormone and various other laboratory parameters, and assessed the amount of sun exposure, dietary vitamin D intake and other risk factors for hypovitaminosis D in 296 internal medicine inpatients admitted consecutively to the Soroka University Medical Center, which is situated in a sunny region of Israel.

RESULTS

We found hypovitaminosis D (serum 25-HO-D < 15 ng/ml) in 77 inpatients (26.27%). The amount of sunlight exposure, serum albumin concentration, being housebound or resident of a nursing home, vitamin D intake, ethnic group, cerebrovascular accident and glucocorticoid therapy were all significantly associated with hypovitaminosis D. Multivariate analysis showed a significant association between hypovitaminosis D and Bedouin origin, sun exposure, vitamin D intake, and stroke. Hypovitaminosis D was also found among inpatients who reported consuming more than the recommended daily amount of vitamin D. Parathyroid hormone levels were significantly higher in patients with 25-OH-D levels below 15 ng/ml. In a subgroup of 74 inpatients under 65 years old with no known risk factors for hypovitaminosis D, we found 20.3% with hypovitaminosis D.

CONCLUSIONS

Hypovitaminosis D is common in patients hospitalized in internal medicine wards in our region, including patients with no known risk factors for this condition. Based on our findings, we recommend vitamin D supplementation during hospitalization and upon discharge from general internal medicine wards as a primary or secondary preventive measure.

[Incidence of osteoporotic fractures in southern Israel]

BACKGROUND

Very little is known about the epidemiology of osteoporotic fractures in Israel.

AIM

We aimed to provide an estimate on the incidence of low-impact fractures in southern Israel.

METHODS

The study included women and men 50 years and older with radiographic evidence of a new fracture. We screened and reviewed all the emergency room and hospital charts to identify all patients with low impact fractures who attended the Soroka Hospital during the corresponding months of January and February of 1998 through 2001.

RESULTS

There were a total of 580 fracture patients (461 women and 119 men). The estimated incidence of all low-impact fractures in the entire population aged 50 and older was 1064:100,000 (95% C.I. 981: 1153) per year. The estimated incidence of low-impact fractures in women was three fold higher than in men [1526:100,000 (95% C.I. 1390: 1675) vs. 490/100,000 (95% C.I. 408: 580) per year, respectively]. Fractures of the distal forearm and proximal hip (26% each) were, by far, the most common in women, followed by fractures of the humerus (18%), ankle (12%) and pelvis (5%). In men, proximal hip fractures (39%) were the most common, followed by fractures of the humerus (18%), distal forearm (15%) and ankle (14%). Multiple concurrent fractures occurred in 2.5% of the patients.

CONCLUSIONS

Our data provides a preliminary estimate of the incidence of osteoporotic fractures, not including most vertebral collapse fractures, among women and men in southern Israel. Further studies are warranted to characterize fracture risk in other regions of the country and population sub-groups.

Clinical and epidemiologic investigation of two Legionella-Rickettsia co-infections

BACKGROUND

We treated two patients diagnosed with legionellosis and simultaneous Rickettsia conorii co-infection.

OBJECTIVES

To report the clinical and laboratory characteristics of this unusual combination, and to describe the execution and results of our environmental and epidemiologic investigations.

METHODS

Serial serologic testing was conducted 1, 4 and 7 weeks after initial presentation. Water samples from the patients' residence were cultured for Legionella. Follow-up cultures were taken from identical points at 2 weeks and at 3 months after the initial survey.

RESULTS

Both patients initially expressed a non-specific rise in anti-Legionella immunoglobulin M titers to multiple serotypes. By week 4 a definite pattern of specifically elevated IgG titers became apparent, with patient 1 demonstrating a rise in specific anti-L. pneumophila 12 IgG titer and patient 2 an identical response to L. jordanis. At 4 weeks both patients were positive for both IgM and IgG anti-R. conorii antibodies at a titer > or = 1:100. Heavy growth of Legionella was found in water sampled from the shower heads in the rooms of both patients. Indirect immunofluorescence of water cultures was positive for L. pneumophila 12 and for L. jordanis.

CONCLUSIONS

Although most cases of community-acquired Legionella pneumonia in our region appear simultaneously with at least one other causative agent, co-infection with R. conorii is unusual and has not been reported to date. This report illustrates the importance of cooperation between clinicians and public health practitioners.

Impact of subsidizing effective anti-osteoporosis drugs on compliance with management guidelines in patients following low-impact fractures

Early in 2000, proven-effective antiresorptive drugs (alendronate and raloxifene) were included in the national "health basket" in Israel. We carried out the present study to evaluate the effect of subsidizing antiosteoporosis drugs on the use of antiosteoporosis drugs in patients following low-impact fractures. The rates of dispensation of antiosteoporosis drugs, in the hospital and in the community, before and after an incident of a newly diagnosed low-impact fracture, respectively, were evaluated during January and February 1998 and 1999 ("pre-basket") and the corresponding months of 2000 and 2001 ("post-basket"). The study was carried out in a 950-bed teaching hospital, the only one serving the area, and the largest health maintenance organization in the area. Hospital charts of women and men age 50 years and older with new fractures following low- or moderate-impact trauma treated in the emergency room, or admitted to the orthopedic surgery and rehabilitation departments, were reviewed. A centralized pharmacy computerized database was used to follow antiosteoporosis drug dispensation in the community. A significant, approximately two-fold, increase in the baseline (before fracture) rate of osteoporosis drug dispensation was observed between the pre- and post-basket periods. The rate of patients treated after a fracture incident also increased significantly, 1.6 fold, in the post-basket period; however, even in the post-basket period, two-thirds of the patients remained untreated following a fracture incident, and most of those treated received only calcium and vitamin D; only 17% received potent antiosteoporosis drugs. In a multivariate analysis, female gender, hospitalization, having the incident of fracture in the post-basket period, and above all being treated for osteoporosis before the fracture incident, had the greatest effect on the likelihood of being treated following a low-impact fracture incident. The increase in the pooled use of antiosteoporosis drugs and/or calcium/vitamin D supplements was continuous, and subsidizing created no step-up effect, besides a transient increase in the use of potent antiosteoporosis drugs in the first year following the health-basket amendment. We conclude that while subsidizing may have a significant, positive effect on antiosteoporosis drug utilization, other factors may be even more important. There is an ongoing need to find ways to encourage the use of effective pharmacological interventions for primary and secondary prevention of osteoporotic fractures.

Nitric oxide directly activates GABA(A) receptor function through a cGMP/protein kinase-independent pathway in frog pituitary melanotrophs

The direct effects of nitric oxide (NO) donors and sulfhydryl-modifying agents on the GABA(A) receptor function were examined by perforated patch, whole-cell and single channel recordings in cultured frog melanotrophs. In amphotericin B-perforated cells incubated with the soluble guanylyl cyclase inhibitors LY 83583 and ODQ (10-4 M each), the NO donor sodium nitroprusside (SNP) (10(-3) M) reversibly increased the current evoked by GABA (5 x 10(-6) M). In the whole-cell configuration, internal application of the oxidizing agent H2O2 (0.05%) potentiated the GABA-evoked current while the reducing agent 2-mercaptoethanol (5 x 10(-3) M) slightly decreased the current amplitude. In inside-out patches, GABA (2 x 10(-7) M) triggered single channel bursts of openings. Incubation with the NO donors SNP or DEA/NO (10(-4) M each) enhanced the open probability of the GABA(A) receptor channel but did not modify the chloride reversal potential and did not affect the conductance states. The oxidizing agents H2O2 (0.05%) or DTNB (10-4 M) mimicked the stimulatory effect of the NO donors on the open probability while the reducing compounds 2-mercaptoethanol (5 x 10(-3) M) or DTT (10(-4) M) markedly attenuated the channel activity. Potentiation of the GABA-induced single channel activity by SNP or H2O2 was blocked by 2-mercaptoethanol. Similarly, the potentiating effect produced by DEA/NO or DTNB on the open probability was reversed by DTT. In outside-out patches, incubation with SNP also significantly enhanced the open probability of single channels activated by GABA (10(-6) M). These data indicate that, in frog pituitary melanotrophs, NO potentiates the GABA-evoked current independently of the cGMP/protein kinase pathway. The effect of NO can be accounted for by S-nitrosylation/oxidation of thiol groups either directly on the GABA(A) receptor subunits or on a regulatory protein tightly associated with the GABA(A) receptor.

Awareness of osteoporosis and compliance with management guidelines in patients with newly diagnosed low-impact fractures

A pre-existing fracture is a strong predictor of additional osteoporotic fractures. Consequently, current guidelines emphasize the need for treating patients with existing osteoporotic fractures. The present study aimed to assess the implementation of osteoporosis guidelines in routine practice. To this end, we reviewed the hospital charts of women and men aged 50 years and older with new fractures due to low or moderate impact treated in the emergency room, orthopedic surgery and rehabilitation departments. Notation of osteoporosis as a contributing cause for the fracture, performance of screening laboratory tests for possible secondary causes and treatment recommendations were abstracted from the record. In addition, we utilized the centralized pharmacy and laboratory computerized databases of the largest health maintenance organization in the area to follow dispensation of osteoporosis drugs and performance of screening laboratory tests in the community following fracture incidents. During the corresponding periods of January and February 1998 and 1999, 183 patients aged 50 years and older with low-impact fractures were treated in the emergency room only and 113 were hospitalized. Osteoporosis was rarely mentioned in the medical documentation. During the 6 month period after the fracture incident at least 70% of the emergency room patients and 62% of the hospitalized patients received no osteoporosis drugs. However, an encouraging significant trend toward increasing use of osteoporosis drugs, both prior to and after a fracture incident, was noted between the two survey periods among the emergency room fracture patients, but not among the hospitalized patients. Calcium supplements were the most commonly used osteoporosis drug. Bisphosphonates, hormone replacement therapy, raloxifene and calcitonin were rarely prescribed. Men were less likely than women to receive treatment for osteoporosis. Systematic laboratory evaluations for secondary causes of osteoporosis were not performed. We conclude that despite extensive attempts at increasing awareness among health professionals and the public at large, osteoporosis is still rarely singled out as a problem in patients with newly diagnosed low-impact fractures, and the majority of them are not managed according to guidelines. Further studies should address specific problems in physicians' and patients' attitude that may account for the present situation.

Regulation of the GABA(A) receptor by nitric oxide in frog pituitary melanotrophs

Nitric oxide (NO) is implicated in the regulation of various endocrine functions, but the effect of NO on GABA(A) receptor transmission has never been reported in endocrine cells. In the present study, we have investigated the effects of various agents acting on the NO transduction pathway on GABA(A) receptor function in frog pituitary melanotrophs. Histochemical studies using the NADPH-diaphorase reaction and immunohistochemical labeling with antibodies against neuronal NO synthase (nNOS) revealed that nNOS is expressed in the intermediate lobe of the pituitary and in cultured melanotrophs. Whole-cell patch-clamp recordings showed that the specific substrate of NOS L-arginine (L-Arg, 10(-4) M) or the NO donor sodium nitroprusside (10(-5) M) provoked a long-lasting inhibition of the current evoked by GABA (5 x 10(-6) M). The NOS inhibitor L-nitroarginine (10(-5) M) produced a biphasic effect, i.e. a transient decrease followed by a delayed increase of the GABA-evoked current amplitude. Similarly, the specific nNOS inhibitor 7-nitroindazole and the specific inducible NOS (iNOS) inhibitor aminoguanidine (10(-5) M each) provoked a transient depression of the current followed by a sustained potentiation. Formation of cGMP in neurointermediate lobes was enhanced by L-Arg (10(-4) M) and by the calcium-releasing agent caffeine (10(-4) M), and inhibited by the calmodulin (CaM)/Ca2+ complex blocker W7 (10(-5) M). The GABA-evoked current was potentiated by the guanylyl cyclase inhibitor ODQ (10(-8)-10(-7) M) and inhibited by the protein kinase G (PKG) activator 8pCPT-cGMP (3 x 10(-7)-3 x 10(-5) M). The present data indicate that NO, produced by a CaM/Ca2+-dependent NOS in frog melanotrophs, exerts an autocrine inhibitory effect on the GABA-evoked current. The action of NO on the GABA(A) receptor function is mediated through activation of the cGMP/PKG pathway.

Regulation of GABAA receptor by protein tyrosine kinases in frog pituitary melanotrophs

The effects of protein tyrosine kinase (PTK) and PTK inhibitors on the GABAA receptor function were studied in cultured frog pituitary melanotrophs by using the patch-clamp technique. Extracellular application of the PTK inhibitors genistein (10-9 to 10-5 M) or lavendustin A (10-12 to 10-7 M) provoked a bell-shaped potentiation of the whole-cell current induced by GABA (3x10-6 M). In contrast, at high concentrations, genistein (10-4 M) and lavendustin A (10-5 M) reversibly reduced the GABA-evoked current. Daidzein and lavendustin B, the inactive analogs of genistein and lavendustin A, respectively, did not modify the current induced by GABA. In the inside-out configuration, bath application of the recombinant PTK pp60c-src (75 U/ml) inhibited the GABA-activated chloride current, and the inhibitory effect of pp60c-src was prevented by genistein (10-7 M). Immunoblotting revealed that genistein, at doses of 10-7 M or 10-4 M, markedly inhibited tyrosine phosphorylation of the beta2/beta3 subunits of the GABAA receptor. Extracellular application of the PKA activator Bt2cAMP (10-3 M), the PKA/PKC inhibitor H7 (10-5 M) and the Cam KII inhibitor W7 (10-5 M) reversibly diminished the whole-cell GABA-induced current. Internal application of H7 and W7 (10-4 M) did not modify the dose-dependent effects of genistein. Internal application of sodium orthovanadate (10-4 M), a protein tyrosine phosphatase inhibitor, decreased the GABA-evoked current and markedly reduced the potentiating effect of genistein. The present study provides the first evidence that, in frog pituitary melanotrophs, the GABAA receptor is phosphorylated at least on its beta2/beta3 subunits by an endogenous PTK. Our data also demonstrate that tyrosine phosphorylation exerts an inhibitory effect on GABAA receptor function.

Adenosine potentiates the delayed-rectifier potassium conductance but has no effect on the hyperpolarization-activated Ih current in frog melanotrophs

The effects of adenosine on the voltage-sensitive delayed-rectifier K+ (IK) currents and hyperpolarization-activated cationic inward current (Ih) were studied in cultured frog melanotrophs using the whole-cell configuration of the patch-clamp technique. The A1 receptor agonist R-N6-phenylisopropyl-adenosine (R-PIA; 50 microM) reversibly increased IK. Perfusion of dibutyryl-cAMP (1 mM) in the external solution did not modify the R-PIA-induced enhancement of IK. Pretreatment of melanotrophs with pertussis toxin (1 microg/ml; 12 h) totally abolished the R-PIA-evoked response. Application of hyperpolarizing voltage pulses from -60 to -120 mV to melanotrophs induced a two-component inward current corresponding to an Ih-like conductance. This conductance was characterized by a high K+ selectivity and a low Na+ permeability and was resistant to tetrodotoxin (1 microM). R-PIA had no effect on Ih. The present study demonstrates that in frog melanotrophs adenosine inhibits the electrical activity by activating IK through an A1 receptor subtype coupled to a pertussis toxin-sensitive pathway independent of the cAMP/PKA system. This study also demonstrates the existence of a Ih conductance in frog melanotrophs which is not modulated by A1 receptors.

Gramicidin-perforated patch revealed depolarizing effect of GABA in cultured frog melanotrophs

1. In frog pituitary melanotrophs, GABA induces a transient stimulation followed by prolonged inhibition of hormone secretion. This biphasic effect is inconsistent with the elevation of cytosolic calcium and the inhibition of electrical activity also provoked by GABA in single melanotrophs. In the present study, standard patch-clamp configurations and gramicidin-perforated patches were used to investigate the physiological GABAA receptor-mediated response and intracellular chloride concentration ([Cl-]i) in cultured frog melanotrophs. 2. In the gramicidin-perforated patch configuration, 1 microM GABA caused a depolarization associated with an action potential discharge and a slight fall of membrane resistance. In contrast, at a higher concentration (10 microM) GABA elicited a depolarization accompanied by a transient volley of action potentials, followed by a sustained inhibitory plateau and a marked fall of membrane resistance. Isoguvacine mimicked the GABA-evoked responses, indicating a mediation by GABAA receptors. 3. In gramicidin-perforated cells, the depolarizing excitatory effect of 1 microM GABA was converted into a depolarizing inhibitory action when 0.4 microM allopregnanolone was added to the bath solution. 4. After gaining the whole-cell configuration, the amplitude and/or direction of the GABA-evoked current (IGABA) rapidly changed before stabilizing. After stabilization, the reversal potential of IGABA followed the values predicted by the Nernst equation for chloride ions when [Cl-]i was varied. 5. In gramicidin-perforated cells, the steady-state I-V relationships of 10 microM GABA- or isoguvacine-evoked currents yielded reversal potentials of -37.5 +/- 1.6 (n = 17) and -38.6 +/- 2.0 mV (n = 8), respectively. These values were close to those obtained by using a voltage-ramp protocol in the presence of Na+, K+ and Ca2+ channel blockers. The current evoked by 1 microM GABA also reversed at these potentials. 6. We conclude that, in frog pituitary melanotrophs, chloride is the exclusive charge carrier of IGABA. In intact cells, the reversal potential of IGABA is positive to the resting potential because of a relatively high [Cl-]i (26.5 mM). Under these conditions, GABA induces a chloride efflux responsible for a depolarization triggering action potentials. However, GABA at a high concentration or in the presence of the potentiating steroid allopregnanolone exerts a concomitant shunting effect leading to a rapid inhibition of the spontaneous firing.

Multiple modulatory effects of the neuroactive steroid pregnanolone on GABAA receptor in frog pituitary melanotrophs

1. The effects of the neuroactive steroid pregnanolone (5 beta-pregnan-3 alpha-ol-20-one) on the electrical response to GABA were investigated in cultured frog pituitary melanotrophs using the patch-clamp technique. 2. Low concentrations of pregnanolone (0.01-1 microM) in the extracellular solution enhanced the current evoked by submaximal concentrations of GABAA receptor agonists and prolonged the GABA-induced inhibition of the spontaneous action potentials in a dose-dependent manner. 3. Pregnanolone augmented the opening probability of the single GABA-activated channels but did not modify the conductance levels. 4. Pregnanolone (1 microM) shifted the GABA dose-response curve towards the low GABA concentrations, reducing the EC50 from 4.2 to 1.8 microM. 5. Internal cell dialysis with pregnanolone (1 or 10 microM) did not alter the GABA-evoked current. 6. Pregnanolone accelerated the desensitization of both the current and conductance increases caused by GABA. 7. High concentrations of pregnanolone (30 microM) markedly and reversibly diminished the current evoked by 10 microM GABA. 8. At high concentrations (10-30 microM), pregnanolone induced an outward current which reversed at the chloride equilibrium potential. 9. It is concluded that, in frog pituitary melanotrophs, pregnanolone exerts a dual inverse modulation and a direct activation of the GABAA receptor-channel depending on the concentrations of both GABA and steroid. Pregnanolone acts on an extracellular site on the GABAA receptor inducing conformational changes of the receptor-channel complex, resulting in a desensitized less-conducting state.