Effect Of Tamoxifen On Plasma Lipid Profile In Patients Of Breast Cancer

BACKGROUND

To evaluate the effect of Tamoxifen on plasma lipid profile in breast cancer patients presenting at tertiary care hospitals.

METHODS

It was a longitudinal study conducted at the Department of Oncology of Jinnah Postgraduate Medical Center from December 2018 to November 2019. Eighty-eight females aged 26-66 years diagnosed with breast cancer were included in the study using a non-probability consecutive sampling technique. Detailed gynaecological and clinical investigations and detailed history were taken. The blood samples of all the patients were collected and the plasma lipid profile was measured before initiation of Tamoxifen treatment and three- and six-months post-treatment at the clinical laboratory. The plasma lipid profile includes the measurement of Total cholesterol (mg/dl), Triglyceride(mg/dl), High-density Lipoprotein (mg/dl) & Low-density Lipoprotein (mg/dl). SPSS version 23 was used to analyse data.

RESULTS

After treatment, there was a significant reduction in serum cholesterol & Low-density Lipoprotein level by 20.54 mg/dl & 16.46 mg/dl at 3 months (p<0.05), moreover there was a significant increase in Triglyceride by 22.14 at 3 months (p<0.05). No significant difference was observed in High density lipoprotein level at 3 months after using Tamoxifen. At 6 months there was a significant reduction in serum cholesterol and low-density lipoprotein by 32.29mg/dl and 24.11 mg/dl at 6 months (p<0.05), moreover there was a significant increase in Triglyceride level by 42.19 mg/dl at 6 months (p<0.05). No significant difference was observed in High-density lipoprotein level at 6 months after using Tamoxifen.

CONCLUSIONS

Total cholesterol and Low-density Lipoprotein levels showed significant reduction over the period of six months from the baseline with the use of Tamoxifen. Hence Tamoxifen should be considered to have an added advantage on lipid metabolism and therefore, can reduce the risk of cardiovascular events.

Significance of ca15-3 in carcinoma of the breast with Visceral metastases

Background

The most common malignancy and second most common cause of death is breast cancer among women. About 2.09 million fatalities from breast cancer happened in 2018. The objective was to evaluate the elevated CA15-3 in breast cancer patients with visceral metastases presenting at the tertiary care hospital of Karachi.

Methods

It was a cross-sectional study conducted at the Department of Oncology of Jinnah Postgraduate Medical Center from 15th December 2018 to 15th November 2019. Female patients aged 26-80 years diagnosed with visceral metastatic (defined as metastasis to lung, liver, brain and adrenal glands) breast cancer were included in the study. The diagnosis of breast cancer was confirmed on histopathology whereas the metastatic sites were evaluated using physical examination and imaging. The serum CA15-3 concentration was assessed using assay kits. The serum CA15-3 level of 0-32 U/ml was taken as normal range for all the patients whereas CA15-3 level greater than 32 U/L was considered as elevated CA15-3. SPSS version 23 was used to enter and analyze data.

Results

A total of 139 females were included in the study. The mean age & BMI of the patients were reported as 46.5 years & 26.69 kg/m2. In the majority of the patients' metastases were detected in the liver (n=54), 92 in the lungs+ parenchymal disease, 20 in adrenal glands, 12 in pleural effusion and 10 in the brain. Out of 139 patients with visceral metastases, 52(37.4%) had normal CA15-3 level whereas 87 (62.6%) had elevated serum CA15-3 levels (>32 U/L).

Conclusion

The serum CA15-3 tumour marker is elevated significantly in visceral metastases and can be used as a prognostic marker in metastatic breast cancer patients.

Determining the role of service quality, trust and commitment to customer loyalty for telecom service users: a PLS-SEM approach

Purpose

The purpose of this paper is to determine the role of service quality (SQ), trust and commitment to customer loyalty (CL) for telecom service users. Further, the moderating role of gender, marital status and connection type within the model was tested.

Design/methodology/approach

A measurement model was created based on valid 615 responses from Indian TSUs for SQ, trust, commitment and loyalty with the help of partial least squares structural equation modeling (PLS-SEM). Multi-group analysis (MGA) was conducted to understand the moderating effect of marital status, gender and connection type within the model.

Findings

The results suggest that, out of five dimensions of SQ, only responsiveness, assurance and empathy have a significant positive relationship with both commitment and trust. Tangibility has a significant positive relationship with trust only. Both commitment and trust have a significant impact on loyalty. It was noticed that both commitment and trust act as mediators between three SQ dimensions (assurance, empathy and responsiveness) and CL. MGA revealed that empathy and responsiveness positively induce trust in telecom users who are single. Whereas, assurance increases commitment toward telecom service providers in married users. Assurance and empathy significantly contribute toward commitment and trust, respectively, in male users as compared to females. Empathy was found important for postpaid users for trust-building, whereas trust was found to be more important for prepaid users to stay loyal to the service provider.

Originality/value

This article contributes toward understanding the role of SQ, trust and commitment to CL moderated by marital status, gender and connection type in an integrated model concerning telecom service.

Prevalence of Hypertension and its Determinants among Policemen in a City of Haryana, India

Introduction

Noncommunicable diseases (NCDs) kill 40 million people each year, equivalent to 70% of all deaths globally. Cardiovascular diseases account for most NCD deaths or 17.7 million people annually. Police work has been regarded by some researchers as one of the most stressful occupations in the world, and coronary heart disease has been identified as a major cause of mortality in this population.

Materials and Methods

A cross-sectional study was carried out during July 2016-June 2017 among 450 policemen posted in Rohtak city of Haryana selected randomly. The investigator made two measurements of blood pressure. Data were collected using predesigned, pretested, semi-structured interview schedule, and analyzed using the Statistical Package for the Social Sciences version 20.0.

Results

Of 450 participants, 164 (36.4%) participants were found to be hypertensive. Age of study participants, duration of service, rank, and education are significantly associated with the prevalence of hypertension (HTN) among policemen.

Conclusion

HTN in policemen has emerged as an important public health problem. Knowledge of risk factors for HTN may give tracks for prevention in this population. Therefore, it is the need of hour to devise a sound screening strategy to diagnose HTN among policemen and devise a comprehensive strategy for the management of HTN.

An Awake Throughout Approach for Awake Craniotomy: A Perspective from a Resource-Limited Country

BACKGROUND

An awake throughout (AT) approach for awake craniotomy is mostly under utilized. The purpose of this study was to review the efficacy of the technique at our tertiary care center. The primary objective was to identify the incidence of perioperative complications. The secondary objective was to review the patients' satisfaction, satisfaction of surgical team, length of stay (LOS) in special care unit (SCU), and overall LOS in the hospital.

METHODS

The study was a retrospective review of patients data. All patients were treated with the AT technique. This included preoperative assessment, psychologic preparation, and institution of scalp block. The incidence of perioperative complications, including satisfaction of surgical team was noted. The patients' satisfaction and the LOS in SCU and in the hospital was also recorded.

RESULTS

In total, the data from 55 patients were reviewed. Their mean age was 41 years, and 63% were reported to have seizures at presentation. The AT approach was successful in 100% of cases. The incidence of intraoperative seizures was 7.4%, of vomiting was 5.4%, and of conversion to general anesthesia was 0%. The surgical team was able to perform gross total resection in 53% of patients and rated a satisfaction score of 8 out of 10. Postoperative seizures occurred in 5.4% of patients and vomiting in 3.6%. The mean LOS in SCU was 1.2 days, and the overall hospital LOS was 4 days. The patients remained fully satisfied, as evidenced by a mean satisfaction score of 8.6.

CONCLUSION

An AT approach might be very useful in resource-limited setups because of the low incidence of complications, the use of resources, and significant surgeon and patient satisfaction.

Anaesthetic Management of Supratentorial Tumor Craniotomy Using Awake-Throughout Approach

The authors are reporting an anaesthetic management of patient presenting with left parietal lobe space occupying lesion and scheduled for Awake-craniotomy. Awake-throughout approach using scalp block was planned. Among techniques reported for keeping patient awake during the surgery, this one is really underutilized. The successful conduct requires thorough preoperative assessment and psychological preparation. We used powerpoint presentation as a preoperative teaching tool. The anatomical landmark technique was used to institute scalp block, where individual nerves were targeted bilaterally. Patient remained stable throughout and participated actively in intraoperative neurological monitoring. Postoperative period showed remarkable recovery, better pain control, and shorter length of stay in hospital.

Renal Biopsy Findings in Patients with Hypothyroidism: Report of 16 cases

INTRODUCTION

Hypothyroidism is prevalent in India. Its association with renal diseases though not very common but have been described in many studies. Here we are reporting renal biopsy findings in 16 cases, all of whom were already diagnosed cases of hypothyroidism.

AIM

To study renal parenchymal diseases associated in patients with hypothyroidism.

MATERIALS AND METHODS

Formalin fixed paraffin embedded sections of renal biopsy were examined after staining with H&E, PAS and Acid Fuschin Orange G (AFOG) stain. Serum urea/creatinine measurements done by semi-autoanalysers and urine analysis were done by using urine strips and light microscopy.

RESULTS

In 16 cases, M:F ratio was 9:7. Duration of disease varied from 6 months to 14 years. Blood urea and serum creatinine were raised in 10 cases (62.5%) and nephrotic range proteinuria was present in 13 cases (81.25%). Two of the patients had co existing systemic lupus erythaematous. Renal pathology revealed membranous glomerulonephritis (GN) in both cases. In renal biopsy seven cases (43.75%) had pure Membranous Glomerulonephritis (MGN), 4 cases (25%) had mixture of Mesan-gial cell proliferation and membranous Glomerulonephritis(GN) also called MembranoProliferative GN (MPGN). Another four cases (25%) had Focal Segmental Glomerulosclerosis (FSGS) with chronic interstitial nephritis and one case was having minimal change disease.

CONCLUSION

Thus present study concludes that hypothyroidism can cause renal parenchymal disease like membranous GN, mesangiocapillary GN which is also called as membranoproliferative GN and FSGS.

Frequency of Hyperthermia in Acute Ischemic Stroke Patients Visiting a Tertiary Care Hospital

OBJECTIVE

To determine the frequency of hyperthermia in acute ischemic stroke patients visiting a tertiary care hospital in a developing country.

STUDY DESIGN

Cross-sectional, observational study.

PLACE AND DURATION OF STUDY

Medical Wards of Civil Hospital, Karachi, from January to June 2013.

METHODOLOGY

Patients aged ≥18 years of either gender with acute ischemic stroke presenting within 24 hours of onset of symptoms were included. Written informed consent was obtained from all participants as well as approval of ethical review committee of the institute. Axillary temperature by mercury thermometer was monitored at the time of admission and after every 6 hours for 3 days. The data was analyzed using SPSS version 17.0 (SPSS Inc., IL, Chicago, USA).

RESULTS

Atotal of 106 patients of ischemic stroke were included. The mean age of enrolled participants was 60.1 ±9.5 years. Among these, 61 (57.5%) were males and 45 (42.5%) females. Among all patients, 51.9% presented with loss of consciousness, 30.2% with slurred speech, 77.4% with limb weakness, and 9.4% with decrease vision. Atotal of 17 (16%) patients with ischemic stroke developed hyperthermia. When the prevalence of hyperthermia was stratified according to age, among patients of < 60 years of age, 26% developed hyperthermia compared to 7.1% in patients of ≥60 years of age (p=0.008). On gender stratification, among male patients, 14.8% developed hyperthermia compared to 17.8% in female patients (p=0.43).

CONCLUSION

It is concluded from this study that the frequency of hyperthermia in ischemic stroke was 16% and it should be looked for as it has significant impact on the outcome. The hyperthermia was significantly more common in younger adults as compared to older adults. However, gender had no influence on the prevalence rate of hyperthermia.

Diabetes education program for people with type 2 diabetes: An international perspective

BACKGROUND

In the Palestinian community, lifestyle changes, rapid urbanization and socioeconomic development, stress, smoking, and changes in food habits has increased the risk of non-communicable diseases especially diabetes mellitus. Diabetes complications can be prevented if the glycemic status of patients with diabetes is maintained within a nearly normal range. Therefore, patient education is critical in controlling blood glucose levels within the normal range.

OBJECTIVE

This study aimed at measuring the effect of diabetes educational intervention program for patients suffering from type 2 diabetes attending the Diabetes Clinic in Tulkarim Directorate of Health.

METHODS

A short duration observational study involving pre- and post-test educational intervention program was carried out on a relatively small number of type 2 diabetes patients at the Diabetes Clinic in Tulkarim Directorate of Health. In total, 215 patients attended a group-based 4h educational intervention session about diabetes. The program included explaining diabetes mellitus-symptoms, risk factors, types, treatment and complications and main aspects of self-care of the disease (foot care, eye care, and blood glucose monitoring), main aspects of dietary management, weight reduction, blood pressure, smoking cessation, periodic investigations, home monitoring and importance of physical activity. Knowledge evaluation questionnaire were evaluated pre- and post-study. Anthropometric measurements such as body weight (WT), body mass index (BMI) and laboratory tests such as fasting blood glucose (FBG), hemoglobin A1C (HbA1c), cholesterol (Chol), and triglycerides (TG) were measured both at the beginning and at the end of the study. Significance of the results was assessed by paired t-test at 95% confidence interval.

RESULTS

The participant's mean age was 51.07 that ranged between 31 and 70 years. For a total of 215 participants, 41.4% were males and 58.6% were females. The mean weight before educational intervention was 80.81±14.95kg (82.6kg for males and 79.5kg for females) that decreased to 78.9±14.33kg (81.1kg for males and 77.3kg for females) after educational intervention program. The BMI also decreased significantly after educational intervention. The mean fasting blood sugar was 188.65±71.45mg/dL before educational intervention that decreased to 177.7±66.11mg/dL after the educational intervention (p=0.049). The mean glycosylated hemoglobin was 8.57±1.21 before educational intervention that decreased to 7.95±1.42 after educational intervention. The mean value of cholesterol before educational intervention was 183.27±37.74mg/dL that decreased to 169.57±34.23mg/dL after educational intervention. The mean triglycerides value decreased after educational intervention from 209.85±171.04mg/dL to 183.28±152.4mg/dL (p=0.025). The mean score of knowledge questionnaire before educational intervention was 60.6±20.65 that increased to 78.1±13.4 after conducting educational intervention.

CONCLUSIONS

Diabetes education was found to be effective on BMI, FBG, HbA1c, Chol, TG, and knowledge.

RECOMMENDATIONS

Diabetes education is a cornerstone in the management and care of diabetes and should be an integral part of health planning involving patient's family, diabetes care team, community, and decision makers in the education process.

The Presence of Human Chorionic Gonadotropin/Luteinizing Hormone Receptors in Pancreatic β-Cells

We investigated the possible presence of functional human chorionic gonadotropin (hCG)/luteinizing hormone (LH) receptors in β-cells of pancreas, using a combination of techniques on hCG/LH receptor knockout mice, immortalized rat insulinoma cells, and human pancreatic islets. The results showed the presence of receptors and their activation resulted in a dose-dependent increase in glucose-induced release of insulin. These findings place hCG and LH among the regulators of insulin release with potential implications for insulin-level changes during the periods of altered hCG and LH secretion.

Validation of Grace Risk Score in predicting in-hospital mortality in patients with non ST-elevation myocardial infarction and unstable angina

OBJECTIVE

To validate the global registry of acute coronary event (grace) risk score in a Pakistani population at Tabba Heart Institute Karachi in patients with non ST-Elevation Myocardial Infarction (NSTEMI) and Unstable Angina (UA).

METHODS

In this prospective Observational registry study, 530 adults hospitalized patients with a diagnosis of Non-ST-Elevation Myocardial Infarction and unstable angina were enrolled between March 2012 and August 2012 at the Tabba Heart Institute, Karachi, Pakistan. For each patient, the grace risk score was calculated and its discrimination evaluated and correlated with in-hospital mortality using the Kendall's tau-b bivariate correlation test. Each patient was grouped either into high, intermediate or low risk groups according to their GRS.

RESULTS

A total of 530 patients with NSTEMI and UA were included; the overall mean grace risk score in our population was 131.87 +/- 41.56. The GRACE Risk Score showed good discrimination, with Area under the ROC curve of 0.803 (95% CI 0.705-0.902, P < 0.001). During the in-hospital stay, total of 19 (3.6%) patients died, and out of those 15 (8.4%) patients belonged to high risk group.

CONCLUSION

GRACE RS strongly validates the in-hospital mortality among our patient population presenting with a wide spectrum of complications. However, more multicentre registries on a larger population with long-term follow up are required to study detailed trends in our population.

Translation initiation factor 5A in Picrorhiza is up-regulated during leaf senescence and in response to abscisic acid

Translation initiation, the first step of protein synthesis process is the principal regulatory step controlling translation and involves a pool of translation initiation factors. In plants, from recent studies it is becoming evident that these translation initiation factors impact various aspects of plant growth and development in addition to their role in protein synthesis. Eukaryotic translation initiation factor eIF5A is one such factor which functions in start site selection for the eIF2-GTP-tRNAi ternary complex within the ribosomal-bound preinitiation complex and also stabilizes the binding of GDP to eIF2. In the present study we have cloned and analysed a gene (eIF5a) encoding eIF5A from Picrorhiza (Picrorhiza kurrooa Royle ex Benth.) a medicinal plant of the western Himalayan region. The full length eIF5a cDNA consisted of 838 bp with an open reading frame of 480 bp, 88 bp 5' untranslated region and 270 bp 3' untranslated region. The deduced eIF5A protein contained 159 amino acids with a molecular weight of 17.359 kDa and an isoelectric point of 5.59. Secondary structure analysis revealed eIF5A having 24.53% α-helices, 8.81% β-turns, 23.27% extended strands and 43.40% random coils. pk-eIF5a transcript was found to be expressing during the active growth phase as well as during leaf senescence stage, however, highest expression was observed during leaf senescence stage. Further, its expression was up-regulated in response to exogenous application of abscisic acid. Both high intensity as well as low intensity light decreased the expression of pk-eIF5a. The findings suggest eIF5a to be an important candidate to develop genetic engineering based strategies for delaying leaf senescence.

A connectivity model for assessment of HIV transmission risk in injection drug users (IDUs)

The purpose of this study was to produce models composed of mapping of connectivity networks of HIV transmission risk in injection drug users (IDUs). This methodology provided a novel approach and diagnostic tool for understanding HIV infection transmission risk and drug use in the typical niche of IDUs, i.e., a "shooting gallery" (a gathering site for injection drug activity). Furthermore, component IDUs may have memberships in multiple "shooting galleries" revealing subsequent interconnectivities. Charting of IDU connectivity diagrams illustrated the relationships of peripheral sites to the critical central core of high HIV transmission risk. Members of this highly interlinked and infectious central core of IDUs had high HIV transmission risk and severe drug use-producing high morbidity and mortality that resulted in great public health concern. In addition, connectivity diagrams reveal very high HIV transmission risk in component IDUs in "dual memberships", i.e., membership in more than one central core (with the highest number of partners). Therefore, IDUs with "dual memberships" were the most infectious members of the "shooting gallery". In summation, network mapping of HIV transmission risk in IDUs allows for subsequent socio-behavioral analysis and the development of focused individual and programmatic interventions.

Reactive oxygen species via redox signaling to PI3K/AKT pathway contribute to the malignant growth of 4-hydroxy estradiol-transformed mammary epithelial cells

The purpose of this study was to investigate the effects of 17-β-estradiol (E2)-induced reactive oxygen species (ROS) on the induction of mammary tumorigenesis. We found that ROS-induced by repeated exposures to 4-hydroxy-estradiol (4-OH-E2), a predominant catechol metabolite of E2, caused transformation of normal human mammary epithelial MCF-10A cells with malignant growth in nude mice. This was evident from inhibition of estrogen-induced breast tumor formation in the xenograft model by both overexpression of catalase as well as by co-treatment with Ebselen. To understand how 4-OH-E2 induces this malignant phenotype through ROS, we investigated the effects of 4-OH-E2 on redox-sensitive signal transduction pathways. During the malignant transformation process we observed that 4-OH-E2 treatment increased AKT phosphorylation through PI3K activation. The PI3K-mediated phosphorylation of AKT in 4-OH-E2-treated cells was inhibited by ROS modifiers as well as by silencing of AKT expression. RNA interference of AKT markedly inhibited 4-OH-E2-induced in vitro tumor formation. The expression of cell cycle genes, cdc2, PRC1 and PCNA and one of transcription factors that control the expression of these genes - nuclear respiratory factor-1 (NRF-1) was significantly up-regulated during the 4-OH-E2-mediated malignant transformation process. The increased expression of these genes was inhibited by ROS modifiers as well as by silencing of AKT expression. These results indicate that 4-OH-E2-induced cell transformation may be mediated, in part, through redox-sensitive AKT signal transduction pathways by up-regulating the expression of cell cycle genes cdc2, PRC1 and PCNA, and the transcription factor - NRF-1. In summary, our study has demonstrated that: (i) 4-OH-E2 is one of the main estrogen metabolites that induce mammary tumorigenesis and (ii) ROS-mediated signaling leading to the activation of PI3K/AKT pathway plays an important role in the generation of 4-OH-E2-induced malignant phenotype of breast epithelial cells. In conclusion, ROS are important signaling molecules in the development of estrogen-induced malignant breast lesions.

The impact of computerized physician order entry on medication errors and adverse drug events

OBJECTIVES

Medication errors and adverse drug events (ADEs) are common, costly, and clinically important problems. This research was conducted to determine whether computerized physician order entry (CPOE) improves the quality of care by increasing patient safety and decreasing medication errors at the King Fahad Medical City Hospital (KFMCH) of the Kingdom of Saudi Arabia (KSA).

METHODS

The study utilized a cross-sectional research design. Questionnaires were distributed to physicians in various departments who used the system for more than six months. The study was conducted in Riyadh at KFMCH, which is the largest medical complex hospital in the Middle East, in the outpatient setting.

KEY FINDINGS

Ninety-three physicians participated in the study; the response rate was 31 percent. Only descriptive analyses were conducted. Results showed that 88 percent of the physicians agreed that the use of CPOE improved their performance and 76 percent reported that the use of CPOE increased their productivity. In addition, 56 percent of the participants agreed that CPOE was a simple system and 64 percent reported that it was easy to use. However, 44 percent of the physicians agreed that CPOE lacked a user guide during medication ordering and 55 percent reported that it created new types of errors. Results showed that 234 physicians always changed their order, 179 physicians changed their order often, 175 physicians rarely changed their order, and 74 physicians never changed their order. Furthermore, 72 percent of the physicians agreed that CPOE helped them to decrease ADEs. Finally, 91 percent of the physicians agreed that CPOE reduced errors related to hand-written prescriptions.

Strict glycemic control and mortality risk among US adults with type 2 diabetes

OBJECTIVE

To assess the relationships between strict HbA1c levels and mortality risk among adults with type 2 diabetes by age, insulin therapy, and hypertension comorbidity.

METHODS

Data of adult participants with type 2 diabetes from the third National Health and Nutrition Examination Survey (1988-1994) and its linked mortality file (with follow-up death up to 2000) were used.

RESULTS

Having strict glycemic control (i.e., HbA1c ≤6.5%) was associated with a lower risk of mortality (hazards ratio=0.69; 95% confidence interval=0.48-0.98). However, among those with strict glycemic control levels, statistically significant results were not found.

CONCLUSION

Reaching strict glycemic control levels in the general US population with type 2 diabetes appears to be associated with lower mortality. Further research is needed as to how strict glycemic control affects certain diabetic groups.

Long work hours is associated with suboptimal glycemic control among US workers with diabetes

BACKGROUND

Increasing numbers of US workers are diabetic. We assessed the relationship between glycemic control and work hours and type of occupation among employed US adults with type 2 diabetes.

METHODS

Data were obtained from the 1999-2004 National Health and Nutrition Examination Survey (NHANES). A representative sample of employed US adults ≥20 years with self-reported type 2 diabetes (n = 369) was used. Two dichotomous glycemic control indicators, based on various HbA1c level cut-points, were used as dependent variables in weighted logistic regression analyses with adjustment for confounders.

RESULTS

Adults working over 40 hr/week were more likely to have suboptimal glycemic control (HbA1c ≥ 7%) compared to those working 20 hr or less (odds ratio = 5.09; 95% confidence interval: [1.38-18.76]).

CONCLUSIONS

Work-related factors, such as number of hours worked, may affect the ability of adults with type 2 diabetes to reach and maintain glycemic control goals. These factors should be considered in the development of workplace policies and accommodations for the increasing number of workers with type 2 diabetes.

L-histidine sensing by calcium sensing receptor inhibits voltage-dependent calcium channel activity and insulin secretion in β-cells

AIMS

Our goal was to test the hypothesis that the histidine-induced activation of calcium sensing receptor (CaR) can regulate calcium channel activity of L-type voltage dependent calcium channel (VDCC) due to increased spatial interaction between CaR and VDCC in β-cells and thus modulate glucose-induced insulin secretion.

MAIN METHODS

Rat insulinoma (RINr1046-38) insulin-producing β-cells were cultured in RPMI-1640 medium on 25 mm diameter glass coverslips in six-well culture plates in a 5% CO(2) incubator at 37°C. The intracellular calcium concentration, [Ca(2+)](i), was determined by ratio fluorescence microscopy using Fura-2AM. The spatial interactions between CaR and L-type VDCC in β-cells were measured by immunofluorescence confocal microscopy using a Nikon C1 laser scanning confocal microscope. The insulin release was determined by enzyme-linked immunosorbent assay (ELISA).

KEY FINDINGS

The addition of increasing concentrations of L-histidine along with 10 mM glucose resulted in 57% decrease in [Ca(2+)](i). The confocal fluorescence imaging data showed 5.59 to 8.62-fold increase in colocalization correlation coefficient between CaR and VDCC in β-cells exposed to L-histidine thereby indicating increased membrane delimited spatial interactions between these two membrane proteins. The insulin ELISA data showed 54% decrease in the 1st phase of glucose-induced insulin secretion in β-cells exposed to increasing concentrations of L-histidine.

SIGNIFICANCE

L-histidine-induced increased spatial interaction of CaR with VDCC can inhibit calcium channel activity of VDCC and consequently regulate glucose-induced insulin secretion by β-cells. The L-type VDCC could therefore be a potential therapeutic target in diabetes.

Glucose-mediated spatial interactions of voltage dependent calcium channels and calcium sensing receptor in insulin producing β-cells

AIMS

The voltage dependent calcium channel (VDCC) e.g., L-type VDCC plays critical roles in the spatio-temporal regulation of intracellular calcium concentration ([Ca(2+)](i)) and insulin secretion by β-cell. This study describes the involvement of 2.5 to 15mM glucose-induced spatial interactions between a calcium sensing receptor (CaR) and L-type VDCC in controlling Ca(2+) channel activity and insulin secretion in β-cells in association with the nuclear translocation of a transcription factor nuclear factor kappa B (NF-κB).

MAIN METHODS

The insulin producing β-cells were exposed to 2.5, 5, 7.5, 10, and 15 mM glucose for 24 h at 37 °C. The confocal fluorescence imaging data was obtained by using antibodies against CaR and L-type VDCC. The nuclear translocation of NF-κB was measured by confocal fluorescence imaging using antibody against NF-κB. The insulin release was determined by enzyme-linked immunosorbent assay (ELISA).

KEY FINDINGS

The confocal imaging data showed 6 to 12-fold enhancement in the colocalization correlation coefficient between CaR and VDCC in β-cells exposed to glucose thereby indicating increased membrane delimited spatial interactions between these two membrane proteins. The confocal fluorescence imaging data showed that addition of glucose to β-cells led to 1.8 to 2.7-fold increase in the nuclear translocation of NF-κB. The insulin ELISA data showed a significant increase in the 1st phase of glucose-induced insulin secretion in β-cells exposed to increasing concentrations of glucose.

SIGNIFICANCE

The results described in the present study further strengthen that VDCC and CaR can interact spatially to allow control over calcium channel activity and therefore glucose-induced insulin secretion by β-cells.

Tumor necrosis factor-α induces transcriptional activation of nuclear factor-κB in insulin-producing β-cells

We previously showed that tumor necrosis factor-α (TNF-α) induces the dysregulation of intracellular calcium [Ca(2+)](i) in β-cells by decreasing the levels of the cytoplasmic Ca(2+) binding protein calbindin-D(28k). The purpose of the present study was to test the hypothesis that TNF-α-induced dysregulation of [Ca(2+)](i) in insulin-producing β-cells causes proteolytic degradation of IκBα and consequently leads to the transcriptional activation of nuclear factor-κB (NF-κB). To test this hypothesis, rat insulinoma (RINr 1046-38) cells, which are an insulin-secreting transformed β-cell line that constitutively expresses calbindin-D(28k), were treated with increasing concentrations of TNF-α. Using the FunctionELISA procedure to measure degradation of the IκBα subunit as Phospho-IκBα, it was found that, while in the control RIN cell lysate there was no Phospho-IκBα present, in the RIN cells exposed to 2, 5, 10, 20 and 30 ng/ml TNF-α, 17.176±2.85, 17.292±4.35, 53.77±5.63, 30.58±4.89 and 12±3.27 ng/ml Phospho-IκBα/mg of total cell protein was observed, respectively (n=3, P<0.05). Upon treatment of RIN cells with 2, 5, 10, 20 and 30 ng/ml TNF-α, the relative increases in the NF-κB transcriptional activities based on the DNA binding activity of NF-κB determined using an ELISA-based kit were 6.86±0.76-, 8.42±1.27-,7.8±2.32-, 10.28±1.96- and 6.3±1.57-fold, respectively (n=3, P<0.05). The nuclear translocation of NF-κB measured by immunofluorescence showed that, while the ratio of fluorescence in nuclei to that in the cytoplasm of untreated RIN cells was 0.2078±0.0778 (n=11), in RIN cells treated with 10 ng/ ml TNF-α, the ratio was 0.6267±0.1186 (n=11), indicating a statistically significant increase (P<0.05) in the nuclear translocation of NF-κB. These observations suggest that, in insulin-producing β-cells, the TNF-α-induced degradation of IκBα leads to nuclear translocation and the transcriptional activation of NF-κB.

Calcium wave signaling in cancer cells

Ca(2+) functions as an important signaling messenger right from beginning of life to the final moments of the end of life. Ca(2+) is needed at several steps of the cell cycle such as early G(1), at the G(1)/S, and G(2)/M transitions. The Ca(2+) signals in the form of time-dependent changes in intracellular Ca(2+) concentrations, [Ca(2+)](i), are presented as brief spikes organized into regenerative Ca(2+) waves. Ca(2+)-mediated signaling pathways have also been shown to play important roles in carcinogenesis such as transformation of normal cells to cancerous cells, tumor formation and growth, invasion, angiogenesis and metastasis. Since the global Ca(2+) oscillations arise from Ca(2+) waves initiated locally, it results in stochastic oscillations because although each cell has many IP(3)Rs and Ca(2+) ions, the law of large numbers does not apply to the initiating event which is restricted to very few IP(3)Rs due to steep Ca(2+) concentration gradients. The specific Ca(2+) signaling information is likely to be encoded in a calcium code as the amplitude, duration, frequency, waveform or timing of Ca(2+) oscillations and decoded again at a later stage. Since Ca(2+) channels or pumps involved in regulating Ca(2+) signaling pathways show altered expression in cancer, one can target these Ca(2+) channels and pumps as therapeutic options to decrease proliferation of cancer cells and to promote their apoptosis. These studies can provide novel insights into alterations in Ca(2+) wave patterns in carcinogenesis and lead to the development of newer technologies based on Ca(2+) waves for the diagnosis and therapy of cancer.

Gonadotrophin-releasing hormone nerve terminals, tanycytes and neurohaemal junction remodelling in the adult median eminence: functional consequences for reproduction and dynamic role of vascular endothelial cells

Although coordinated actions of several areas within the hypothalamus are involved in the secretion of gonadotrophin-releasing hormone (GnRH), the median eminence of the hypothalamus, where the nerve terminals are located, plays a particularly critical role in the release of GnRH. In adult females, prior to the preovulatory surge of GnRH, the retraction of specialised ependymoglial cells lining the floor of the third ventricle named tanycytes allows for the juxtaposition of GnRH nerve terminals with the adjacent pericapillary space of the pituitary portal vasculature, thus forming direct neurohaemal junctions. These morphological changes occur within a few hours and are reversible. Such remodelling may promote physiological conditions to enhance the central release of GnRH and potentiate oestrogen-activated GnRH release. This plasticity involves dynamic cell interactions that bring into play tanycytes, astrocytes, vascular endothelial cells and GnRH neurones themselves. The underlying signalling pathways responsible for these structural changes are comprised of highly diffusible gaseous molecules, such as endothelial nitric oxide, and paracrine communication processes involving receptors of the erbB tyrosine kinase family, transforming growth factor beta 1 and eicosanoids, such as prostaglandin E(2). Some of these molecules, as a result of their ability to diffuse within the median eminence, may also serve as synchronizing cues allowing for the occurrence of functionally meaningful episodes of GnRH secretion by coordinating GnRH release from the GnRH neuroendocrine terminals.

Inflammatory cytokine signaling in insulin producing beta-cells enhances the colocalization correlation coefficient between L-type voltage-dependent calcium channel and calcium-sensing receptor

The immunological processes in type 1 diabetes and metabolic/inflammatory disorder in type 2 diabetes converge on common signaling pathway(s) leading to beta-cell death in these two diseases. The cytokine-mediated beta-cell death seems to be dependent on voltage-dependent calcium channel (VDCC)-mediated Ca2+ entry. The Ca2+ handling molecular networks control the homeostasis of [Ca2+]i in the beta-cell. The activity and membrane density of VDCC are regulated by several mechanisms including G protein-coupled receptors (GPCRs). CaR is a 123-kDa seven transmembrane extracellular Ca2+ sensing protein that belongs to GPCR family C. Tumor necrosis factor-alpha (TNF-alpha), is a cytokine widely known to activate nuclear factor-kappaB (NF-kappaB) transcription in beta-cells. To obtain a better understanding of TNF-alpha-induced molecular interactions between CaR and VDCC, confocal fluorescence measurements were performed on insulin-producing beta-cells exposed to varying concentrations of TNF-alpha and the results are discussed in the light of increased colocalization correlation coefficient. The insulin producing beta-cells were exposed to 5, 10, 20, 30, and 50 ng/ml TNF-alpha for 24 h at 37 degrees . The cells were then immunolabelled with antibodies directed against CaR, VDCC, and NF-kappaB. The confocal fluorescence imaging data showed enhancement in the colocalization correlation coefficient between CaR and VDCC in beta-cells exposed to TNF-alpha thereby indicating increased membrane delimited spatial interactions between these two membrane proteins. TNF-alpha-induced colocalization of VDCC with CaR was inhibited by nimodipine, an inhibitor of L-type VDCC thereby suggesting that VDCC activity is required for spatial interactions with CaR. The 3-D confocal fluorescence imaging data also demonstrated that addition of TNF-alpha to RIN cells led to the translocation of NF-kappaB from the cytoplasm to the nucleus. Such molecular interactions between CaR and VDCC in tissues possibly provide control over Ca2+ channel activity via direct protein-protein contact.

Noninsulinoma pancreatogenous hypoglycemia syndrome: quantitative and immunohistochemical analyses of islet cells for insulin, glucagon, somatostatin, and pancreatic and duodenal homeobox protein

OBJECTIVE

To present a case of an elderly man with noninsulinoma pancreatogenous hypoglycemia syndrome (NIPHS) and to determine the pathogenesis of this syndrome.

METHODS

The pancreas of our patient with NIPHS was immunocytochemically stained for insulin-, glucagon-, and somatostatin-secreting cells and pancreatic and duodenal homeobox protein (PDX-1). The clinical findings and morphologic and immunocytochemical analyses of the islets of our patient are described, along with a review of related published reports.

RESULTS

A 78-year-old man presented with hyperinsulinemic hypoglycemia, with episodes unrelated to meals or fasting. An insulinoma could not be localized by preoperative imaging or by intraoperative ultrasonography or palpation. He underwent a 70% distal pancreatectomy. For assessment of the possibility that a nuclear transcription factor regulating islet beta-cell growth and development is overexpressed in this disease and is responsible for diffuse islet hyperfunction and proliferation of beta-cells, pancreatic sections from our patient were stained immunocytochemically for PDX-1, insulin, glucagon, and somatostatin. Morphologic findings were compared with pancreatic sections from normal control patients and normative data reported in the literature. Clinical findings and morphologic analyses were consistent with NIPHS. Islets were arranged in long clusters, both in the pancreatic tissue and in peripancreatic adipose tissue. Islets were small but increased in number, and insulin, glucagon, and somatostatin were present in the islets. The relative intensity of insulin staining was increased in our patient in comparison with that in the control patients, and PDX-1 was not overexpressed.

CONCLUSION

The etiopathogenesis of NIPHS in this patient involved (1) an increased number of islets with development of ectopic islets in the peripancreatic adipose tissue; (2) alpha- and delta- as well as beta-cell proliferation; and (3) an early step in the development of the islet not involving overexpression of PDX-1.

Neonatal Bartter syndrome

A pre-term baby girl was born following a pregnancy complicated by severe polyhydramnios at a gestational age of 36 weeks. She was initially suffering from respiratory distress consistent with idiopathic respiratory distress syndrome, and altered electrolyte imbalance with hyponatremia, hypokalemia and hypochloremic metabolic alkalosis. However, during the third week of life when she had dehydration along with significant electrolyte imbalance, Bartter's syndrome was considered which was supported by findings of high renin and aldosterone levels. Treatment was done by correction of electrolytes and dehydration along with indomethacin. The drug was well tolerated. The infant showed correction of electrolyte imbalance. The features of this case suggest an extreme form of Bartter's syndrome presenting from the early days of life. The syndrome is reported because of it's rarity and alerts pediatricians to the antenatal and neonatal variant of Bartter's syndrome.

Estrogen exerts a spatial and temporal influence on reactive oxygen species generation that precedes calcium uptake in high-capacity mitochondria: implications for rapid nongenomic signaling of cell growth

Novel findings that emerged from this study underscore the fact that the dynamic nature of mitochondria leads to functional heterogeneity of [Ca(2+)](mito) with respect to estrogen actions in MCF7 cells. We show that estrogen exposure to cells increased [Ca(2+)](mito) in a high-calcium capacity mitochondrial population but not in low-calcium capacity mitochondria. Physiological concentrations of 17beta-estradiol (E2) modulated Ca(2+)(mito) uptake within 90 s. Interestingly, this calcium response lagged behind the induction of mitochondrial reactive oxygen species (mtROS). The rapid induction of Ca(2+)(mito) in response to E2 and its inhibition by mitochondrial blockers suggest that mitochondria are early nongenomic targets of E2. This suggests that a subpopulation of mitochondria is recruited to respond to new metabolic requirements required by estrogen triggers or, as in this case, E2-induced Ca(2+)(mito) and/or mtROS promotes oxidative signaling without involving nuclear estrogen receptor signaling. Although the early E2-induced Ca(2+) did not alter the expression of genes involved in calcium signaling pathways, an intracellular calcium chelator BAPTA-AM and the Ca(2+)(mito) uniporter blocker ruthenium red prevented E2-induced cell growth. We have shown recently that E2-mediated ROS production controls the promoter activity of cyclin D1 by post-translational modification of calcium sensitive transcription factor CREB. The findings of this study offer a new paradigm that rapid E2-induced changes in mtROS and Ca(2+)(mito) are involved in cell cycle progression presumably through the control of early cell cycle genes. Targeting mitochondria to disrupt communication between mitochondria and ROS/Ca(2+) signaling pathways may provide the basis for a novel anticancer strategy for the treatment of estrogen-dependent breast cancer.

Pattern of admissions to neonatal unit

OBJECTIVE

To document the number, disease pattern and outcome of patients admitted to neonatal unit.

DESIGN

Descriptive study.

PLACE AND DURATION OF STUDY

The study was conducted in the Neonatal Unit of National Institute of Child Health, Karachi, Pakistan from 1st January 2001 to 31st December 2001.

PATIENTS AND METHODS

The data of all the admitted neonates was analyzed for age and weight at the time of admission, sex, duration of stay, cause of admission and outcome.

RESULTS

A total of 1984 neonates were admitted during study period. Among them 62.1% were males, 17.54% were admitted within 6 hours of their life, and 51.36% within 72 hours of birth. The low birth weight accounted for 55.4% admissions. Neonatal infection was the major cause of admission (45.21%) comprising 30.64% cases of septicemia, 9.82% of pneumonia and 4.73% of meningitis. Other causes of admission were birth asphyxia (18.85%), neonatal jaundice (13.15%), pre-term (6.87%), meconium aspiration syndrome (3.67%), hemorrhagic disease of newborn (2.21%), diarrhea (2.11%) and hyaline membrane disease (1.05%). 48.53% were discharged with satisfactory condition, 25.5% died and 25.85% left against medical advice (LAMA) and or discharged on request (DoR).

CONCLUSION

Low birth weight (LBW), infections and birth asphyxia were the major causes of neonatal admission.

Estrogen-induced mitochondrial reactive oxygen species as signal-transducing messengers

We report here evidence in support of the role of 17beta-estradiol- (E2-) induced mitochondrial (mt) reactive oxygen species (ROS) as signal-transducing messengers. On the basis of monitoring the oxidation of 2',7'-dichlorofluorescin by spectrofluorometry, flow cytometry, and confocal microscopy, we have identified that exposure of E2 triggers the immediate rapid production of intracellular ROS ranging from a 1- to severalfold increase in a variety of cells. E2-stimulated ROS production does not correlate with the activity of the estrogen receptor (ER) in the cells. The ROS is most likely hydrogen peroxide based on its inhibition by antioxidants and catalase and lack of any effects of E2 on O(2)(*)(-) or NO(*) formation. Confocal microscopy showed that ROS is localized in the perinuclear mitochondria. E2 through anchorage- and integrin-dependent signaling to mitochondria increased ROS generation. Increased intracellular ROS formation identified here for the first time may explain the mechanism of previously reported oxidative damage and subsequent genetic alterations including mutations produced by elevated concentrations of estrogens. The functional consequences of E2-induced ROS formation included the enhanced cell motility as shown by the increase in cdc42 and activation of Pyk2 and the increased phosphorylation of signaling proteins c-jun and CREB. E2-induced ROS activated the binding of three oxidant-sensitive transcription factors: AP-1, CREB, and nuclear respiratory factor 1. In addition to ERs as signaling molecules, our findings further revealed that E2-induced mt ROS also act as signal transducing messengers and suggest new targets for the development of antioxidant-based drugs or antioxidant gene therapy for the prevention and treatment of estrogen-dependent cancer.

Tumor necrosis factor-α-induced changes in insulin-producing β-cells

The migration of macrophages and lymphocytes that produce cytokines such as tumor necrosis factor-alpha (TNF-alpha) causes beta-cell death, leading to type 1 diabetes. Similarly, in type 2 diabetes, the adipocyte-derived cytokines including TNF-alpha are elevated in the circulation, causing inflammation and insulin resistance. Thus, the studies described in this article using TNF-alpha are relevant to furthering our understanding of the pathogenesis of diabetes mellitus. We used RINr1046-38 (RIN) insulin-producing beta-cells, which constitutively express calbindin-D(28k), to characterize the effect of TNF-alpha on apoptosis, replication, insulin release, and gene and protein expression. Western blots of TNF-alpha-treated RIN cells revealed a decrease in calbindin-D(28k). By ELISA, TNF-alpha-treated beta-cells had 47% less calbindin-D(28k) than controls. In association with the decline in calbindin-D(28k), TNF-alpha treatment of RIN cells led to a 73% greater increase in changes in intracellular calcium concentration (Delta[Ca(2+)](i)) in TNF-alpha-treated cells as compared to that in control RIN cells upon treatment with 50 mM KCl; caused a greater increase in the [Ca(2+)](i) following the addition of 5.5 microM ionomycin; increased by more than threefold the apoptotic rate, expressed as the percentage of TUNEL-positive nuclei to total nuclei; decreased the rate of cell replication by 36%; and increased and decreased selectively the expression of specific genes as determined by microarray analysis. The subcellular localizations of Bcl-2, an antiapoptotic protein, and Bax, a proapoptotic protein, within RIN cells were altered with TNF-alpha treatment such that the two were colocalized with mitochondria in the perinuclear region. We conclude that the proapoptotic action of TNF-alpha on beta-cells is manifested via decreased expression of calbindin-D(28k) and is mediated at least in part by [Ca(2+)](i).

Pyloric atresia associated with epidermolysis bullosa--three cases presenting in three months

Three neonates presenting with pyloric atresia and epidermolysis bullosa are described in this report. Two babies underwent surgery for pyloric atresia, and 1 of these has survived until 3 months of age with no complications. The clinical presentation and complications of the pyloric atresia-epidermolysis bullosa syndrome are discussed with a brief review of literature.

Calbindin-D28k and calcium sensing receptor cooperate in MCF-7 human breast cancer cells

The metastases of breast cancer cells to bone result in osteolysis and release of Ca2+. Ca2+ as a primary signal transducer can regulate the expression patterns of cell signaling systems. The extracellular calcium ion concentration sensing receptor CaR is a 123 kDa G-protein coupled membrane protein that resides within caveolin-rich regions as a dimer. CaR is involved in regulating several cellular processes such as proliferation, differentiation, secretion, and apoptosis. Calbindin-D28k is a 28 kDa high affinity calcium-binding protein and it is involved in regulating the intracellular calcium ion concentration, [Ca2+]i, and thus influences signal transduction. The role of CaR in sensing and responding to extracellular calcium ion concentration, [Ca2+]o, and neomycin sulfate, and spatial interactions of CaR with calbindin-D28k in MCF-7 human breast cancer cells were studied. Fura-2 loaded MCF-7 cells were exposed to increasing concentrations of CaCl2 or neomycin sulfate and the [Ca2+]i was determined by ratio fluorescence microscopy. The step-wise addition of CaCl2 or neomycin sulfate caused an increase in [Ca2+]i. The normalized dose response curves fitting yielded Hill co-efficient values of 4.32+/-0.63 and 1.49+/-0.14 for Ca2+ and neomycin sulfate respectively, thus indicating highly co-operative, 4-5 binding sites for Ca2+ and 1-2 binding site(s) for neomycin sulfate on CaR. The EC50 values were 21+/-1.6 mM and 43+/-3.5 micro M for CaCl2 and neomycin sulfate respectively. The confocal microscopy data, obtained by using a highly sensitive tyramide signal amplification technology for immunofluorescence detection, showed CaR and calbindin-D28k were co-localized when cells were exposed to 200 micro M neomycin sulfate, whereas in control cells there was no co-localization of these two proteins. We hypothesize that sensing and responses to increasing [Ca2+]o that occur through CaR, increase the [Ca2+]i causing the translocation of Ca2+-bound calbindin-D28k towards CaR.

Ca(2+) sensing receptor activation by CaCl(2) increases [Ca2+]i resulting in enhanced spatial interactions with calbindin-D28k protein

The extracellular calcium ion concentration, [Ca2+]o, sensing receptor CaR is a G-protein coupled membrane receptor and it is involved in regulating cell proliferation, differentiation, secretion, and apoptosis. Calbindin-D28k is a high affinity calcium-binding protein that plays important roles in modulating the intracellular calcium ion concentration, [Ca2+]i, and thus influences signal transduction. The role of CaR in sensing and responding to [Ca2+]o and spatial interactions of CaR with calbindin-D28k in a distal tubule-like renal cell line are described. Fura-2 loaded Madin Darby bovine kidney (MDBK) cells were exposed to increasing concentrations of CaCl2 and the [Ca2+]i was determined by ratio fluorescence microscopy. The step-wise addition of CaCl2 caused continual increase in [Ca2+]i. The thapsigargin induced increase in [Ca2+]i observed in basal medium was eliminated by pretreatment of MDBK cells with 10 mM CaCl2 thereby suggesting the involvement of endoplasmic reticulum Ca2+ stores in increasing the [Ca2+]i. CaR was localized in the plasma membrane by using confocal microscopy. The confocal microscopy data also showed CaR and calbindin-D28k were co-localized when cells were exposed to 40 mM CaCl2. We postulate that sensing and responses to increasing [Ca2+]o that occur through CaR, increase the [Ca2+]i causing the translocation of Ca2+-bound calbindin-D28k towards CaR.

Birth asphyxia--analysis of 235 cases

OBJECTIVE

To look for risk factors leading to birth asphyxia in new borns admitted in a tertiary care unit

STUDY DESIGN

Retrospective analysis.

SETTING

Neonatal Unit of National Institute of Child Health, Karachi from 1st January, 2001 to 31st August, 2001.

PATIENTS AND METHODS

Records of 235 new borns admitted with birth asphyxia during this period were analyzed. Variables studied included antenatal care, period of gestation, place of delivery, mode of delivery, birth weight and age at arrival in the hospital.

RESULTS

Majority (71%) of mothers were booked and had antenatal care, similarly most (88%) of the babies were born at term and 75.3% were delivered in maternity homes or hospitals. Caesarian sections were performed in 14% cases and rest were all vaginal deliveries. Fifty seven percent newborns weighed more than 2.5 kg and 22.5% presented to the hospital within 6 hours of birth.

CONCLUSION

Birth asphyxia occurring in such a high number of booked cases delivered at term with good weight, reflects the poor perinatal services offered in those maternity homes or hospitals. It is recommended that trained personnel and neonatal resuscitation equipment should be made mandatory in all maternity homes/hospitals.

Intracellular calcium ion response to glucose in beta-cells of calbindin-D28k nullmutant mice and in betaHC13 cells overexpressing calbindin-D28k

This article describes studies on the glucose-induced responses of intracellular Ca2+ concentration ([Ca2+]i), insulin release, and redistribution of calbindin-D28k, a calcium-binding regulatory protein, in beta-cells of pancreatic islets of calbindin-D28k knockout (KO) and wild-type mice (C57BL6) as well as in betaHC-13 control cells and betaHC-13 CaBP40 cells (beta-cell line overexpressing calbindin-D28k). Upon increasing the glucose concentration from 2.8 to 30 mM, islets of KO mice showed a significantly greater increase in [Ca2+]i (mean increase in [Ca2+]i, i.e., delta[Ca2+]i, was 296 nM) compared with wild-type mice (delta[Ca2+]i = 97 nM). betaHC-13 CaBP40 cells showed little change in [Ca2+]i upon elevation of glucose from 5.5 to 32.7 mM, whereas betaHC-13 control cells exhibited significant increases in [Ca2+]i, (delta[Ca2+]i = 510 nM). Similarly, upon addition of 30 mM glucose, the rate of insulin release increased from 25.2 (basal rate) to 145.2 pg/mL/min in betaHC-13 control cells, whereas in betaHC-13 CaBP40 cells the rate of insulin release was only 27.5 pg/mL/min in high glucose. Thus, levels of calbindin-D28k in beta-cells affect both [Ca2+]i and insulin secretion in response to glucose. The three-dimensional reconstruct of confocal immunofluorescent images showed that glucose caused redistribution of calbindin-D28k resulting in co-localization in the region of L-type voltage-dependent calcium channels (VDCC). This co-localization may be an important regulatory function concerning Ca2+ influx via L-type VDCC and exocytosis of insulin granules.

Ca2+-dependent actin remodeling in the contracting A7r5 cell

Previous work has shown that stimulation of contraction in A7r5 smooth muscle cells with phorbol ester (PDBu) results in the disassembly and remodeling of the alpha-actin component of the cytoskeleton (Fultz et al., 2000, J Mus Res Cell Motil 21: 775-781). In the present study, we evaluated the effect of increasing intracellular calcium ion concentration [Ca2+]i by A23187 and thapsigargin on alpha- and beta-actin remodeling. The effects of A23187 and thapsigargin on cell contraction and actin remodeling were effectively identical. The two compounds caused contraction of A7r5 cells that was earlier in onset and more quickly completed than PDBu-induced contractions. Both the alpha- and beta-actin isoforms were incorporated into stress cables in the resting cell. During the interval of contraction, beta-actin cables shortened without evidence of disassembly. By comparison, the increase of [Ca2+]i resulted in partial or complete dissolution of alpha-actin cables without further remodeling. In addition, PDBu-mediated alpha-actin remodeling was blocked in the presence of A23187. Increased [Ca2+]i also caused dispersal of alpha-actinin but had no effect on the cellular distribution of talin suggesting the effect was selective for alpha-actin cytoskeletal structure. The incubation of cells in calcium-free media prevented alpha-actin dissolution by A23187/thapsigargin and also blocked PDBu-mediated remodeling. Finally, of six kinase inhibitors investigated, only ML-7 partially blocked the dissolution of alpha-actin cables by increased [Ca2+]i. The results suggest that the sustained elevation of [Ca2+]i beyond a threshold level initiates depolymerization of alpha-actin but not beta-actin. It further appears that PDBu-induced alpha-actin remodeling requires Ca2+ but increases of [Ca2+]i beyond a threshold level may inhibit this activity. The finding that ML-7 partially inhibits alpha-actin dissolution in the presence of A23187/thapsigargin may be suggesting that myosin light chain kinase (MLCK) plays a role in destabilizing alpha-actin structure in the activated cell.

Prescribing practices of consultants at Karachi, Pakistan

OBJECTIVE

To audit the prescribing practices of consultants.

DESIGN

A randomized sample survey of 354 consultants prescription for analysis of some basic parameters as recommended by World Health Organization (WHO).

MAIN OUTCOME MEASURES

To provide feedback to the prescribers for promoting rational drug therapy.

RESULTS

The average number of drugs for prescription were found to be 4.51 and the average daily cost of prescribed drugs was Rs: 133.41. The antimicrobials, vitamins/minerals and injections were over-prescribed. About half of the prescribed drugs were from the National Essential Drugs List of Pakistan (NEDLP) and only a little over 12% were prescribed by their generic names.

CONCLUSIONS

The prescribing practices of the consultants in Karachi are rather liberal and not rational. Overuse of antimicrobials and injections have been observed and there is general tendency of indulging in polypharmacy requiring continued medical education.

Depolarized resonance light scattering by porphyrin and chlorophyll a aggregates

A quantum mechanical model is developed for the observed resonance enhancement of light scattering by aggregates of electronically interacting chromophores. Aggregate size, monomer oscillator strength, extent of electronic coupling, and aggregate geometry are all important determinants of intensity in resonance light scattering (RLS) spectra. The theory also predicts the value of the depolarization ratio (rho(v)(90)) of RLS for a given aggregate geometry. These results are used to interpret the RLS depolarization ratios of four aggregates: tetrakis(4-sulfonatophenyl)porphine aggregated at low pH (rho(v)(90) = 0.17 at 488 nm), trans-bis(N-methylpyridinium-4-yl)-diphenylporphinato copper(II) aggregated in 0.2 M NaCl solution (rho(v)(90) = 0.13 at 450 nm) and on calf thymus DNA (rho(v)(90) = 0.20 at 454 nm), and chlorophyll a aggregates in formamide/water (rho(v)(90) = 0.23 and 0.32 at 469 and 699 nm, respectively). The analysis is consistent with a J-aggregate geometry for all four systems. Furthermore, the specific values of rho(v)(90) allow us to estimate the orientation of the monomer transition dipoles with respect to the long axis of the aggregate. We conclude that depolarized resonance light scattering spectroscopy is a powerful probe of the geometric and electronic structures of extended aggregates of strong chromophores.

pHi and serum regulate AE2-mediated ClŐ/HCOŐ3, exchange in CHOP cells of defined transient transfection status

Page C855: L. Jiang, A. Stuart-Tilley, J. Parkash, and S. L. Alper. “pHi and serum regulate AE2-mediated Cl-/HCO-3, exchange in CHOP cells of defined transient transfection status.” The acknowledgment section omitted our thanks to Genetics Institute and Dana Dubois for subsidizing the additional cost of publication in color.