Red blood cell derived extracellular vesicles during the process of autologous blood doping

The purpose of this pilot study was to investigate the effects of the transfusion of one erythrocyte concentrate on the number of circulating red blood cell extracellular vesicles (RBC-EVs) and their clearance time. Six, healthy volunteers donated their blood and were transfused with their RBC concentrate after 35-36 days of storage. One K₂ EDTA and one serum sample were collected before donation, at four timepoints after donation and at another six timepoints after transfusion. RBC-EVs were analyzed on a Cytek Aurora flow cytometer. A highly significant increase (p < 0.001) of RBC-EVs from an average of 60.1 ± 19.8 (10³ /μL) at baseline to 179.3 ± 84.7 (10³ /μL) in the first 1-3 h after transfusion could be observed. Individual differences in the response to transfusion became apparent with one volunteer showing no increase and another an increased concentration at one timepoint after donation due to an influenza infection. We concluded that in an individualized passport approach, increased RBC-EVs might be considered as additional evidence when interpreting suspicious Athletes Biological Passport (ABPs) but for this additional research related to sample collection and transport processes as well as method development and harmonization would be necessary.

Neurolymphomatosis of the median nerve, optic nerve, L4 spinal nerve root and cauda equina in patients with B-cell malignancies: a case series

BACKGROUND

Neurolymphomatosis is rare. Neoplastic lymphocytes are seen to invade nerves (cranial or peripheral), nerve roots or other related structures in patients with hematological malignancy. It is a separate entity from central nervous system lymphoma. Neurolymphomatosis has most commonly been described in association with B-cell non-Hodgkin lymphoma. Neurolymphomatosis in the context of Burkitt lymphoma and the post-renal transplant setting has not been described before.

CASE REPORTS

We report for the first time in the Arabian Gulf countries and nearby Arab states four cases of neurolymphomatosis (one Asian, and the other 3 are from Arabic nationals) occurring between 2012 and 2017 involving the median nerve, optic nerve, nerve root and cauda equina in patients with Burkitt lymphoma, Philadelphia chromosome-positive B-cell acute lymphoblastic leukemia and diffuse large B-cell lymphoma.

CONCLUSIONS

Neurolymphomatosis is rare and can be difficult to diagnose by biopsy but reliably confirmed by a combined imaging approach. Prior treatment with high-dose dexamethasone might suppress 18F-fluorodeoxyglucose (FDG) activity and decrease the sensitivity of positron emission tomography/computed tomography (PET/CT). The prognosis is generally poor but using high-dose methotrexate as well as high-dose chemotherapy and autologous stem cell transplantation may be an effective way to treat neurolymphomatosis.

Endophthalmitis resulting from gonococcal keratoconjunctivitis

Neisseria gonorrhoeae is a global pathogen with significant morbidity. This bacterium is one of the common causes of sexually transmitted diseases; however, ocular gonococcal infection is rare. The gonococcal ocular infection can lead to ulcerative keratitis and/or corneal perforation. We report a case of endophthalmitis resulting from gonococcal keratoconjunctivitis. Sexual transmission could not be proven in this patient.

Maps of variability in cell lineage trees

New approaches to lineage tracking have allowed the study of differentiation in multicellular organisms over many generations of cells. Understanding the phenotypic variability observed in these lineage trees requires new statistical methods. Whereas an invariant cell lineage, such as that for the nematode Caenorhabditis elegans, can be described by a lineage map, defined as the pattern of phenotypes overlaid onto the binary tree, a traditional lineage map is static and does not describe the variability inherent in the cell lineages of higher organisms. Here, we introduce lineage variability maps which describe the pattern of second-order variation in lineage trees. These maps can be undirected graphs of the partial correlations between every lineal position, or directed graphs showing the dynamics of bifurcated patterns in each subtree. We show how to infer these graphical models for lineages of any depth from sample sizes of only a few pedigrees. This required developing the generalized spectral analysis for a binary tree, the natural framework for describing tree-structured variation. When tested on pedigrees from C. elegans expressing a marker for pharyngeal differentiation potential, the variability maps recover essential features of the known lineage map. When applied to highly-variable pedigrees monitoring cell size in T lymphocytes, the maps show that most of the phenotype is set by the founder naive T cell. Lineage variability maps thus elevate the concept of the lineage map to the population level, addressing questions about the potency and dynamics of cell lineages and providing a way to quantify the progressive restriction of cell fate with increasing depth in the tree.

Operational research within a Global Fund supported tuberculosis project in India: why, how and its contribution towards change in policy and practice

BACKGROUND

The Global Fund encourages operational research (OR) in all its grants; however very few reports describe this aspect. In India, Project Axshya was supported by a Global Fund grant to improve the reach and visibility of the government Tuberculosis (TB) services among marginalised and vulnerable communities. OR was incorporated to build research capacity of professionals working with the national TB programme and to generate evidence to inform policies and practices.

OBJECTIVES

To describe how Project Axshya facilitated building OR capacity within the country, helped in addressing several TB control priority research questions, documented project activities and their outcomes, and influenced policy and practice.

METHODS

From September 2010 to September 2016, three key OR-related activities were implemented. First, practical output-oriented modular training courses were conducted (n = 3) to build research capacity of personnel involved in the TB programme, co-facilitated by The Union, in collaboration with the national TB programme, WHO country office and CDC, Atlanta. Second, two large-scale Knowledge, Attitude and Practice (KAP) surveys were conducted at baseline and mid-project to assess the changes pertaining to TB knowledge, attitudes and practices among the general population, TB patients and health care providers over the project period. Third, studies were conducted to describe the project's core activities and outcomes.

RESULTS

In the training courses, 44 participant teams were supported to develop research protocols on topics of national priority, resulting in 28 peer-reviewed scientific publications. The KAP surveys and description of project activities resulted in 14 peer-reviewed publications. Of the published papers at least 12 have influenced change in policy or practice.

CONCLUSIONS

OR within a Global Fund supported TB project has resulted in building OR capacity, facilitating research in areas of national priority and influencing policy and practice. We believe this experience will provide guidance for undertaking OR in Global Fund projects.

How Ethiopia achieved Millennium Development Goal 4 through multisectoral interventions: a Countdown to 2015 case study

BACKGROUND

3 years before the 2015 deadline, Ethiopia achieved Millennium Development Goal 4. The under-5 mortality decreased 69%, from 205 deaths per 1000 livebirths in 1990 to 64 deaths per 1000 livebirths in 2013. To understand the underlying factors that contributed to the success in achieving MDG4, Ethiopia was selected as a Countdown to 2015 case study.

METHODS

We used a set of complementary methods to analyse progress in child health in Ethiopia between 1990 and 2014. We used Demographic Health Surveys to analyse trends in coverage and equity of key reproductive, maternal health, and child health indicators. Standardised tools developed by the Countdown Health Systems and Policies working group were used to understand the timing and content of health and non-health policies. We assessed longitudinal trends in health-system investment through a financial analysis of National Health Accounts, and we used the Lives Saved Tool (LiST) to assess the contribution of interventions towards reducing under-5 mortality.

FINDINGS

The annual rate of reduction in under-5 mortality increased from 3·3% in 1990-2005 to 7·8% in 2005-13. The prevalence of stunting decreased from 60% in 2000 to 40% in 2014. Overall levels of coverage of reproductive, maternal health, and child health indicators remained low, with disparities between the lowest and highest wealth quintiles despite improvement in coverage for essential health interventions. Coverage of child immunisation increased the most (21% of children in 2000 vs 80% of children in 2014), followed by coverage of satisfied demand for family planning by women of reproductive age (19% vs 63%). Provision of antenatal care increased from 10% of women in 2000 to 32% of women in 2014, but only 15% of women delivered with a skilled birth attendant by 2014. A large upturn occurred after 2005, bolstered by a rapid increase in health funding that facilitated the accelerated expansion of health infrastructure and workforce through an innovative community-based delivery system. The LiST model could explain almost 50% of the observed reduction in child mortality between 2000 and 2011; and changes in nutritional status were responsible for about 50% of the 469 000 lives saved between 2000 and 2011. These developments occurred within a multisectoral policy platform, integrating child survival and stunting goals within macro-level policies and programmes for reducing poverty and improving agricultural productivity, food security, water supply, and sanitation.

INTERPRETATION

The reduction of under-5 mortality in Ethiopia was the result of combined activities in health, nutrition, and non-health sectors. However, Ethiopia still has high neonatal and maternal morbidity and mortality from preventable causes and an unfinished agenda in reducing inequalities, improving coverage of effective interventions, and strengthening multisectoral partnerships for further progress.

FUNDING

Bill & Melinda Gates Foundation and Government of Canada.

Satisfaction with a 2-day communication skills course culturally tailored for medical specialists in Qatar

OBJECTIVE:

Health-care communication skills training may be particularly needed in the Arabian Gulf countries because of the variety of cultures within the physician and patient populations. This study describes the implementation and results of a communication skills training program for physicians in Qatar that assessed previous training, and effect of previous training on participants' course evaluations.

MATERIALS AND METHODS:

We conducted a 2-day communication skills training course covering seven culturally adapted modules. Educational strategies included large and small group work with the standardized patient, demonstration videos, and lectures. At the end, participants completed a course evaluation survey. Data analysis performed with SPSS; frequencies and percentages were calculated, and Chi-square test applied to evaluate statistical significance.

RESULTS:

A total of 410 physicians in Qatar have participated in the course over a period of 2 years. Evaluation ratings of the course were high. Participants rated the module on Breaking Bad News as the most useful, and the small group role-play as the most helpful course component. One-third of participants had previously participated in experiential communication skills training. There was no association between previous experience and evaluation of the course.

CONCLUSION:

Physicians in Qatar positively evaluated a 2-day communication skills course, though the majority of participants did not have any previous exposure to experiential communication skills training.

Countdown to 2015 country case studies: what can analysis of national health financing contribute to understanding MDG 4 and 5 progress?

BACKGROUND

Countdown to 2015 (Countdown) supported countries to produce case studies that examine how and why progress was made toward the Millennium Development Goals (MDGs) 4 and 5. Analysing how health-financing data explains improvements in RMNCH outcomes was one of the components to the case studies.

METHODS

This paper presents a descriptive analysis on health financing from six Countdown case studies (Afghanistan, Ethiopia, Malawi, Pakistan, Peru, and Tanzania), supplemented by additional data from global databases and country reports on macroeconomic, health financing, demographic, and RMNCH outcome data as needed. It also examines the effect of other contextual factors presented in the case studies to help interpret health-financing data.

RESULTS

Dramatic increases in health funding occurred since 2000, where the MDG agenda encouraged countries and donors to invest more resources on health. Most low-income countries relied on external support to increase health spending, with an average 20-64 % of total health spending from 2000 onwards. Middle-income countries relied more on government and household spending. RMNCH funding also increased since 2000, with an average increase of 119 % (2005-2010) for RMNH expenditures (2005-2010) and 165 % for CH expenditures (2005-2011). Progress was made, especially achieving MDG 4, even with low per capita spending; ranging from US$16 to US$44 per child under 5 years among low-income countries. Improvements in distal factors were noted during the time frame of the analysis, including rapid economic growth in Ethiopia, Peru, and Tanzania and improvements in female literacy as documented in Malawi, which are also likely to have contributed to MDG progress and achievements.

CONCLUSIONS

Increases in health and RMNCH funding accompanied improvements in outcomes, though low-income countries are still very reliant on external financing, and out-of-pocket comprising a growing share of funds in middle-income settings. Enhancements in tracking RMNCH expenditures across countries are still needed to better understand whether domestic and global health financing initiatives lead to improved outcomes as RMNCH continues to be a priority under the Sustainable Development Goals.

A scoring system for the prediction of choledocholithiasis: a prospective cohort study

BACKGROUND

Techniques for diagnosing choledocholithiasis pose significant morbidity and mortality risks.

OBJECTIVES

We aimed to develop and validate a clinical scoring system for predicting choledocholithiasis.

DESIGN

Data from a prospectively maintained database of all patients with gallstones.

SETTING

Patients were admitted to the general surgery department of a military hospital.

PATIENTS AND METHODS

We enrolled consecutive patients with symptomatic gallstones, biliary pancreatitis, obstructive jaundice, or cholangitis, who subsequently underwent biochemical testing and ultrasonography. A predictive model was developed from a scoring system using their imaging and laboratory data. Endoscopic retrograde cholangiopancreatography (ERCP) or intraoperative cholangiography were used for confirmatory diagnoses. The predictive efficacy of the scoring system was validated using a retrospective cohort of 272 patients.

MAIN OUTCOME MEASURES

Predictive accuracy of the scoring system.

RESULTS

We enrolled 155 patients in the development group. The common bile duct diameter, alkaline phosphatase of >=200 IU, elevated bilirubin levels, alanine transaminase of >=220 IU, and male age of >=50 years were significantly associated with choledocholithiasis and were included in the scoring system. Ninety-six patients (35%) had scores of >=8 (high risk), 86 patients (32%) had scores of 4-7 (intermediate risk), and 27 patients (10%) had scores of 1-3 (low risk). In the validation cohort, the positive predictive value for a score of >=8 was 91.7%, and the scoring system had an area under the curve of 0.896.

CONCLUSION

Scores of >=8 were strongly correlated with choledocholithiasis in the developmental and validation groups, which indicates that our scoring system may be useful for predicting the need for therapeutic ERCP. However, prospective validation in a large multicenter cohort is needed to fully understand the benefits of the system.

LIMITATIONS

The retrospective validation cohort might have introduced selection and observational biases. The study may have been underpowered because of the sample size of the developmental cohort. The delay between admission and the time of ERCP theoretically may have increased the number of negative ERCP results, but our false negative rate for ERCP was consistent with the previously reported rates.

Normalized polarization ratios for the analysis of cell polarity

The quantification and analysis of molecular localization in living cells is increasingly important for elucidating biological pathways, and new methods are rapidly emerging. The quantification of cell polarity has generated much interest recently, and ratiometric analysis of fluorescence microscopy images provides one means to quantify cell polarity. However, detection of fluorescence, and the ratiometric measurement, is likely to be sensitive to acquisition settings and image processing parameters. Using imaging of EGFP-expressing cells and computer simulations of variations in fluorescence ratios, we characterized the dependence of ratiometric measurements on processing parameters. This analysis showed that image settings alter polarization measurements; and that clustered localization is more susceptible to artifacts than homogeneous localization. To correct for such inconsistencies, we developed and validated a method for choosing the most appropriate analysis settings, and for incorporating internal controls to ensure fidelity of polarity measurements. This approach is applicable to testing polarity in all cells where the axis of polarity is known.

Growth hormone deficiency in adults with thalassemia: an overview and the I-CET recommendations

This review paper provides a summary of the current state of knowledge regarding GHD provides recommendations for the diagnosis and treatment of GHD in adult patients with thalassaemia major (TM). The reported prevalence of adult GHD and /or IGF-I deficiency in TM patients varies from 8% to 44 % in different centers. Because GH treatment requires analysis of many factors, including the effect of treatment on cardiac functions, metabolic parameters and psychosocial functioning, along with safety, ethical considerations, financial cost and other burdens of therapy, stringent diagnostic criteria are needed. The authors report the diagnostic recommendations of the International Study Group of Endocrine Complications in Thalassemia (I-CET) for adult TM patients.The pros and cons of GH treatment must be discussed with each patient, after which GH doses should be individualized and titrated to maximum efficacy with minimal side effects. Prospective studies to monitor potential benefits versus possible side-effects will enable endocrinologists to define recommendations on dosage and the long term effects, particularly on cardiovascular and bone status of GH therapy in adult TM patients.

Continuous glucose monitoring, oral glucose tolerance, and insulin - glucose parameters in adolescents with simple obesity

In obese adolescents pancreatic beta-cells may not be able to cope with insulin resistance leading to hyperglycemia and type2 diabetes (T2DM To assess oral glucose tolerance, 72-h continuous blood glucose concentrations (CGM) and calculate homeostatic model assessment (HOMA), and the quantitative insulin sensitivity check index (QUICKI) in 13 adolescents with simple obesity (BMI SDS=4 ± 1.06). OGTT performed in 13 obese adolescents (13.47 ± 3 years) revealed 3 cases (23%) with impaired fasting glucose (IFG: fasting glucose >5.6 mmol/L), 4 cases (30%) with impaired glucose tolerance (IGT: 2h blood glucose >7.8 <11.1 mmol/L), and none with diabetes. Using the continuous glucose monitoring system ( CGMS), IFG was detected in 4 cases, the maximum serum blood glucose (BG : 2h or more after meal) was >7.8 and <11.1 mmol/L (IGT) in 9 children (69%) and >11.1 mmol/L (diabetes) in one case (7.6%). Five cases had a minimum BG recorded of <2.7 mmol/L (hypoglycemia). No glycemic abnormality was detected using HbA1C (5.7 ± 0.3%). 11/13 patients had HOMA values >2.6 and QUICKI values <0.35 denoting insulin resistance. Beta cell mass percent (B %) = 200 ± 94.8% and insulin sensitivity values (IS)=50.4 ± 45.5% denoted insulin resistance with hyper-insulinaemia and preserved beta cell mass. In obese adolescents, CGMS is superior to OGTT and HbA1C in detecting glycemic abnormalities, which appears to be secondary to insulin resistance.

Gemcitabine Plus Carboplatin in Patients with Advanced Hepatocellular Carcinoma: Results of a Phase II Study

Objectives. Assessment of gemcitabine/carboplatin combination in patients with advanced-stage hepatocellular carcinoma (HCC) in a phase II trial for safety and efficacy. Methods. Forty patients with previously untreated advanced-stage HCC were prospectively enrolled and subjected to gemcitabine/carboplatin regimen which consisted of gemcitabine 1000 mg/m² on days 1 and 8, and carboplatin AUC 6 on day 1. The treatment was repeated every 3 weeks until disease progression or limiting toxicity. Results. Forty patients were assessable for efficacy and toxicity. In all, 276 treatment cycles were administered. No toxic deaths occurred. Hematological grade 3-4 toxicity consisted of thrombocytopenia (27% of patients) and neutropenia (24%), including 2 febrile neutropenia and anemia (9%). Grade 3 carboplatin-induced neurotoxicity was observed in 3 (9%) patients. ORR was 23% (95% CI, 0.10–0.29) with 9 partial responses and disease stabilization was observed in 46% (95% CI, 0.22–0.42) of patients, giving a disease control rate of 69%. Median progression-free and overall survival times were, respectively, 5 months (95% CI: 3–8 months) and 8 months (95% CI: 6–18 months). Conclusion. The gemcitabine/carboplatin regimen seems to be effective, well tolerated, and active in advanced HCC.

Acquired pure megakaryocytic aplasia successfully treated with cyclosporine

Acquired pure megakaryocytic aplasia is a rare hematological disorder characterized by thrombocytopenia with absent or markedly reduced megakaryocytes in the bone marrow. We report a case of a 25-year-old male diagnosed as acquired pure megakaryocytic aplasia. Treatment with prednisone and intravenous immunoglobulin failed, but he was successfully treated with cyclosporine, with complete remission after 90 days and normal platelet count maintained thereafter.

Two Ocular Infections during Conventional Chemotherapy in a Patient with Acute Lymphoblastic Leukemia: A Case Report

Viral retinitis due to cytomegalovirus (CMV) infection is rare in patients with acute leukemia who did not receive hematopoietic stem cell transplantation. We report a case of CMV retinitis that developed in a 49-year-old patient with acute lymphoblastic leukemia. The patient was treated with salvage chemotherapy using a hyper-CVAD regimen and did not receive hematopoietic stem cell transplantation. The incidence of CMV retinitis in this subgroup of patients is not described in literature. He had a very complicated course during chemotherapy but was successfully treated, with preservation of visual acuity, and to date he is in complete remission. Interestingly, prior to CMV retinitis, the patient had been diagnosed with and treated for candida retinitis. This case shows the importance of eye examination and care in patients diagnosed with hematological malignancies.

Interferon gamma, interferon-gamma-induced-protein 10, and tuberculin responses of children at high risk of tuberculosis infection

BACKGROUND

Children in contact with adults with pulmonary tuberculosis (TB) are at risk for infection and disease progression, and chemoprophylaxis may reduce this risk. The identification of infection is based on the tuberculin skin test (TST) and interferon-gamma (INF-gamma) release assays. Other biomarkers such as interferon-gamma-induced-protein 10 (IP-10) may have potential for the diagnosis of latent TB infections.

OBJECTIVES

To describe IP-10 concentrations and their association to TST and INF-gamma responses in children recently exposed to adults with smear-positive TB in Brazil and Nepal.

METHODS

: Two surveys using the same design were undertaken to describe TST, INF-gamma, and IP-10 responses in 146 children in Nepal and 113 children in Brazil.

RESULTS

The concordance of TST and QuantiFERON-TB gold in-tube (QFT-IT) was high (kappa 0.73 in Brazil and 0.80 in Nepal). IP-10 responses were higher in children with both positive TST and positive QFT-IT (medians 1434 pg/mL in Brazil and 1402 pg/mL in Nepal) and lowest in children with both negative TST and negative QFT-IT (medians 206 pg/mL in Brazil and 81 pg/mL in Nepal). Children with negative TST and positive QFT-IT had higher IP-10 concentrations than children with positive TST but negative QFT-IT.

CONCLUSIONS

IP-10 is a potential marker to identify latent TB infections that is expressed in large quantities and with good agreement with QFT-IT. The reasons for the discrepant results observed are discussed.

Clinical Quiz: Pyoderma Gangerenosum

52 year old Indian female patient with no significant past medical history presented with a skin lesion started since three weeks associated with fever for three days CBC showed pancytopenia investigations (bone marrow) revealed a very severe Aplastic anemia.

Tuberculous Tenosynovitis: A rare presentation of miliary TB

We present, as a rare manifestation of miliary TB, a case of tuberculous tenosynovitis, preceding by two weeks onset of tuberculous meningitis. A gradual progressive onset of a painless swelling of the right forearm was followed by high-grade fever, headache and neck pain. A suspected diagnosis of tuberculous meningitis based upon analysis of cerebrospinal fluid (CSF) was confirmed later by positive CSF polymerase chain reaction (PCR) for mycobacterium tuberculosis. Although the patient had a positive Mantoux test of 20 mm, there was no evidence of pulmonary TB and a negative CSF smear for acid fast bacilli but a positive smear from a fine needle aspirate of the swelling of the right forearm. The antituberculous therapy led to a successful outcome.

Anti-malarial drug targets: screening for inhibitors of 2C-methyl-D-erythritol 4-phosphate synthase (IspC protein) in Mediterranean plants

The recently discovered non-mevalonate pathway of isoprenoid biosynthesis serves as the unique source of terpenoids in numerous pathogenic eubacteria and in apicoplast-type protozoa, most notably Plasmodium, but is absent in mammalian cells. It is therefore an attractive target for anti-infective chemotherapy. The first committed step of the non-mevalonate pathway is catalyzed by 2C-methyl-D-erythritol 4-phosphate synthase (IspC). Using photometric and NMR spectroscopic assays, we screened extracts of Mediterranean plants for inhibitors of the enzyme. Strongest inhibitory activity was found in leaf extracts of Cercis siliquastrum.

Erythrocyte and brain methionine adenosyltransferase activities in patients with schizophrenia

The activity of methionine adenosyltransferase (MAT) was investigated in erythrocytes and postmortem brain specimens (cortex gyrus frontalis, hippocampus and thalamus) of patients with schizophrenia treated with neuroleptics. In comparison with the control group, abnormally low values of MAT Vmax and an increased MAT affinity towards methionine (lower Km values) were found in erythrocytes. In the brain, a regionally selective decrease of MAT Km was found in cortex gyrus frontalis but the Vmax values were however, unchanged. In the regions of cortex gyrus frontalis and hippocampus, but not in thalamus, the values of Vmax and Km were inversely correlated with the duration of schizophrenia. In rats treated for 28 days with the typical neuroleptic haloperidol and the atypical clozapine, a significant increase of MAT activity was found in the corpus striatum. There is the possibility that the changes observed in MAT activity in patients with schizophrenia are attributed to the neuroleptic medication.

G-protein modulation of neuronal class E (alpha 1E) calcium channel expressed in GH3 cells

GH3 cell lines stably expressing alpha 1E channel were established and the modulation of this channel by G-protein through membrane-delimited pathways was studied. Alpha 1E channel expressed in GH3 cells showed slowing of activation and reduction of current amplitude by the application of carbachol or somatostatin. Both of these effects caused by these agents were pertussis toxin (PTX) sensitive and voltage dependent. Dialysis of the cell interior with GTP gamma S mimicked the action of these externally applied neurotransmitters, indicating that the alpha 1E channel is modulated by the PTX sensitive G-protein(s) through the membrane-delimited pathway but not by the PTX insensitive pathway that has been observed in alpha 1A channel expressed in GH3 cells. Thus different types of neuronal Ca2+ channels can be modulated not only by a similar mechanism but also by a different mechanism conferring a multilateral regulation of Ca2+ entry through these channels.

G-protein modulation of alpha 1A (P/Q) type calcium channel expressed in GH3 cells

GH3 cell lines stably expressing alpha 1A channel were established and the modulation of this channel by G-protein through membrane-delimited pathways were studied. Wild type GH3 cells were found to express omega-conotoxin MVIIC (MVIIC) sensitive Ca2+ current but this component was different from the alpha 1A channel because of its susceptibility to G-protein modulation, suggesting MVIIC also blocks channels other than P/Q type. Alpha 1A channel expressed in GH3 cells showed slowing of activation and reduction of current amplitude by the application of carbachol. Both of these effects were pertussis toxin (PTX) sensitive and voltage dependent. alpha 1A channels were also found to be modulated through a PTX insensitive pathway, the modulations observed were similar to those in the PTX sensitive pathway. The results further suggest that these two effects are governed by a different mechanism in both PTX sensitive and insensitive pathways.

NMDA antagonists increase recovery of evoked potentials from slices of rat olfactory cortex after anoxia

1. The role of glutamate in producing tissue damage during cerebral anoxia was investigated in brain slices using antagonists to the NMDA and AMPA receptor types. 2. Tissue function was assessed by field recordings of the synaptically evoked potentials elicited by stimulating the main afferent input to the olfactory cortex, the lateral olfactory tract. Anoxia was produced by bathing the slice in glucose-free solution equilibrated with 95% N2/5% CO2. 3. The amount of recovery of the evoked potential was inversely dependent on the period of anoxia and temperature: at 24 degrees C, 15 min of anoxia followed by reoxygenation produced a 14.6 +/- 4.1% recovery whereas there was no recovery at 35 degrees C. 4. Dizocilpine and ketamine had no effect on synaptic transmission in oxygenated media but following anoxia they produced an increased recovery of the responses: from 14.6 +/- 4.1% to 48.3 +/- 7.8% for dizocilpine (10 microM) and 21.6 +/- 7.7% to 87.2 +/- 7.1% for ketamine (200 microM); the tissue endurance to anoxia was increased by around 5 min. 5. Blockade of the AMPA receptors did not influence recovery in spite of the depressed synaptic transmission. A similar synaptic attenuation produced by lignocaine provided some increase in post-anoxic recovery. 6. The NMDA receptor antagonist, AP5, antagonized NMDA at 50 microM by 3.7 fold and at 200 microM by 15 fold but only 200 microM increased post-anoxic recovery. This suggests that a substantial degree of NMDA antagonist is required before anoxic tissue damage due to NMDA receptor activation can be nullified. The antagonist to the glycine binding site, 7-chlorokynurenic acid also increased recovery. 7. These in vitro experiments confirm the idea that NMDA receptor activation makes a substantial contribution to cerebral tissue damage and that this can be reduced by a substantial blockade of these receptors.