Kartagener's Syndrome Complicated by Bronchiectasis with Tricuspid and Mitral Valve Regurgitation: A Case Report

Background

Kartagener's syndrome, a rare autosomal recessive genetic disorder, is characterized by primary ciliary dyskinesia (PCD), resulting in defective cilia function in the respiratory tract and fallopian tubes.

Case presentation

This case report discusses a 23-year-old female with Kartagener's syndrome, bronchiectasis, and cardiac involvement, who presented with shortness of breath, cough, and syncope. Notably, she received home oxygen therapy but became exhausted, leading to loss of consciousness. Clinical examination revealed prominent heart sounds and abnormal lung findings. Laboratory results indicated leukocytosis, and an ECG confirmed dextrocardia and cardiac abnormalities. Doppler studies identified mitral and tricuspid regurgitation along with severe pulmonary arterial hypertension. Antibiotics were administered for coagulase-negative Staphylococcus infection. The patient improved with a treatment regimen, including oxygenation and nebulization. Regular follow-up and patient education were emphasized.

Conclusion

This case underscores the complexity of Kartagener's syndrome and the importance of a multidisciplinary approach in managing its respiratory and cardiac manifestations.

Global assessment of tropospheric and ground air pollutants and its correlation with COVID-19

The declaration of COVID-19 pandemic by the WHO initiated a series of lockdowns globally that varied in stringency and duration; however, the spatiotemporal effects of these lockdowns on air quality remain understudied. This study evaluates the global impact of lockdowns on air pollutants using tropospheric and ground-level indicators over a five-month period. Moreover, the relationship between air pollution and COVID-19 cases and mortalities was examined. Changes in the global tropospheric (NO2, aerosols, and O3) and ground-level (PM2.5, PM10, NO2, and O3) pollutants were observed, and the maximum air quality improvement was observed immediately after lockdown. Except for a few countries, a decline in air pollutants correlated with a reduction in Land Surface Temperature (LST). Notably, regions with higher tropospheric NO2 and aerosol concentrations were also COVID-19 hotspots. Our analysis showed moderate positive correlation for NO2 with COVID-19 cases (R2 = 0.33; r = 0.57, P = 0.006) and mortalities (R2 = 0.40; r = 0.63, P = 0.015), while O3 showed a weak-moderate positive correlation with COVID-19 cases (R2 = 0.22; r = 0.47, P = 0.003) and mortalities (R2 = 0.12; r = 0.35, P = 0.012). However, PM2.5, and PM10 showed no significant correlation with either COVID-19 cases or mortality. This study reveals that humans living under adverse air pollution conditions are at higher risk of COVID-19 infection and mortality.

Aminoglycoside-mediated promotion of translation readthrough occurs through a non-stochastic mechanism that competes with translation termination

Attempts have been made to treat nonsense-associated genetic disorders by chemical agents and hence an improved mechanistic insight into the decoding of readthrough signals is essential for the identification and characterisation of factors for the treatment of these disorders. To identify either novel compounds or genes that modulate translation readthrough, we have employed dual reporter-based high-throughput screens that use enzymatic and fluorescence activities and screened bioactive National Institute of Neurological Disease Syndrome (NINDS) compounds (n = 1000) and siRNA (n = 288) libraries. Whilst siRNAs targeting kinases such as CSNK1G3 and NME3 negatively regulate readthrough, neither the bioactive NINDS compounds nor PTC124 promote readthrough. Of note, PTC124 has previously been shown to promote readthrough. Furthermore, the impacts of G418 on the components of eukaryotic selenocysteine incorporation machinery have also been investigated. The selenocysteine machinery decodes the stop codon UGA specifying selenocysteine in natural selenoprotein genes. We have found that the eukaryotic SelC gene promotes the selenocysteine insertion sequence (SECIS)-mediated readthrough but inhibits the readthrough activity induced by G418. We have previously reported that SECIS-mediated readthrough at UGA codons follows a non-processive mechanism. Here, we show that G418-mediated promotion of readthrough also occurs through a non-processive mechanism which competes with translation termination. Based on our observations, we suggest that proteins generated through a non-processive mechanism may be therapeutically beneficial for the resolution of nonsense-associated genetic disorders.

Efficacy of Ayarij Faiqura in Qarah-e-Hazmiya - Randomized controlled Clinical study

Background and Objective: Qarahe Hazmiya (Peptic ulcer disease) is one of the commonest ailment of Gastro intestinal tract, reported to affect around 4% of the population and 10% of people developed it at some point in their life. Etiopathology of the disease is considered as multi factorial mostly treated with medications and rarely with surgery. Several Unani formulation have been indicated effective in Qarahe Hazmiya, one of such formulation has been selected to evaluate its efficacy and to validate the same on scientific parametersMethods: This study was conducted as a single blind, randomized standard control clinical trial on 28 patients (n=20) in test and (n=8) control groups. Test group received Ayarij Faiqura 5gm and control group received Pantoprazole 40 mg, orally in empty stomach for 45 days. The study outcome was assessed as the difference in pre and post treatment through subjective and objective parameters.Result: The test drugs revealed statistically significant improvement in burning sensation in abdomen (p<0.0001), pain abdomen (p<0.0001) as subjective parameters in comparison to control group where as objectivecally endoscopic report showed significantly improvement (p<0.0196) in comparison to control group with respect to the healing of ulcer / erosions.Interpretation and conclusion: The study revealed that the test drug had good response in controlling burning sensation and pain abdomen, along with healing of ulcer / erosions in comparison to control drug. No side effect or toxicity was observed during and or after the study. Thus, it could be concluded that the test drug was found to be safe and effective without any adverse effect.Bangladesh Journal of Medical Science Vol.17(1) 2018 p.112-117

Copper doping enhanced the oxidative stress-mediated cytotoxicity of TiO2 nanoparticles in A549 cells

Physicochemical properties of titanium dioxide nanoparticles (TiO₂ NPs) can be tuned by doping with metals or nonmetals. Copper (Cu) doping improved the photocatalytic behavior of TiO₂ NPs that can be applied in various fields such as environmental remediation and nanomedicine. However, interaction of Cu-doped TiO₂ NPs with human cells is scarce. This study was designed to explore the role of Cu doping in cytotoxic response of TiO₂ NPs in human lung epithelial (A549) cells. Characterization data demonstrated the presence of both TiO₂ and Cu in Cu-doped TiO₂ NPs with high-quality lattice fringes without any distortion. The size of Cu-doped TiO₂ NPs (24 nm) was lower than pure TiO₂ NPs (30 nm). Biological results showed that both pure and Cu-doped TiO₂ NPs induced cytotoxicity and oxidative stress in a dose-dependent manner. Low mitochondrial membrane potential and higher caspase-3 enzyme (apoptotic markers) activity were also observed in A549 cells exposed to pure and Cu-doped TiO₂ NPs. We further observed that cytotoxicity caused by Cu-doped TiO₂ NPs was higher than pure TiO₂ NPs. Moreover, antioxidant N-acetyl cysteine effectively prevented the reactive oxygen species generation, glutathione depletion, and cell viability reduction caused by Cu-doped TiO₂ NPs. This is the first report showing that Cu-doped TiO₂ NPs induced cytotoxicity and oxidative stress in A549 cells. This study warranted further research to explore the role of Cu doping in toxicity mechanisms of TiO₂ NPs.

Rotenone-induced oxidative stress and apoptosis in human liver HepG2 cells

Rotenone, a commonly used pesticide, is well documented to induce selective degeneration in dopaminergic neurons and motor dysfunction. Such rotenone-induced neurodegenration has been primarily suggested through mitochondria-mediated apoptosis and reactive oxygen species (ROS) generation. But the status of rotenone induced changes in liver, the major metabolic site is poorly investigated. Thus, the present investigation was aimed to study the oxidative stress-induced cytotoxicity and apoptotic cell death in human liver cells-HepG2 receiving experimental exposure of rotenone (12.5-250 μM) for 24 h. Rotenone depicted a dose-dependent cytotoxic response in HepG2 cells. These cytotoxic responses were in concurrence with the markers associated with oxidative stress such as an increase in ROS generation and lipid peroxidation as well as a decrease in the glutathione, catalase, and superoxide dismutase levels. The decrease in mitochondrial membrane potential also confirms the impaired mitochondrial activity. The events of cytotoxicity and oxidative stress were found to be associated with up-regulation in the expressions (mRNA and protein) of pro-apoptotic markers viz., p53, Bax, and caspase-3, and down-regulation of anti-apoptotic marker Bcl-2. The data obtain in this study indicate that rotenone-induced cytotoxicity in HepG2 cells via ROS-induced oxidative stress and mitochondria-mediated apoptosis involving p53, Bax/Bcl-2, and caspase-3.

Pulmonary Arterial Hypertension: Molecular Genetic Basis and Emerging Treatments

Pulmonary arterial hypertension (PAH) is a rare cardiovascular disorder caused by narrowing of blood vessels in the lung and in the absence of therapy leads to right heart failure and death. No cure for this devastating disorder is known. The major objective of the current treatments is to improve symptoms and these therapies were developed prior to the discovery that this disease has substantial genetic components. In this review, we discuss molecular      genetic basis of PAH together with pathobiology, current and future therapeutic interventions.   DOI: http://dx.doi.org/10.3329/akmmcj.v3i2.11691   AKMMC J 2012; 3(2): 30-33  

Short-term exposure of 4-hydroxynonenal induces mitochondria-mediated apoptosis in PC12 cells

4-Hydroxynonenal (4-HNE) is one of the most reactive aldehydic by-products of lipid peroxidation. The role of 4-HNE in the etiology of various neurodegenerative disorders including cerebral ischemia/reperfusion, Alzheimer’s disease, Parkinson’s disease, etc. has been documented. We and others have reported that long-term toxic insults of 4-HNE triggers apoptotic signals and oxidative stress in various cells. However, the status of apoptosis following short-term exposure and underlying mechanisms has not been explored so far. We studied the apoptotic changes in PC12 cells receiving short-term exposure of 4-HNE. A significant dose-dependent induction in reactive oxygen species (ROS) and early response markers (c-Fos, c-Jun, and GAP-43) were observed in cells exposed to 4-HNE (10, 25, and 50 µM) for 1h. Following the exposure of PC12 cells to 4-HNE, the levels of protein and messenger RNA expressions of P53, Bax, and caspase 3 were significantly upregulated, whereas the levels of Bcl2 was downregulated. We could record the apoptotic signals and ROS generation in PC12 cells receiving 4-HNE exposure for such a short period of time. Induction in the expression and activity of caspase 3 has also indicated the mitochondrial mediation in the apoptosis induction.

Role of Magnetic Resonance Imaging in Evaluation of Tubercular Spondylitis: Pattern of Disease in 100 Patients with Review of Literature

Introduction: The purpose of this study is to evaluate the role of magnetic resonance imaging (MRI) in evaluation of tubercular spondylitis and to correlate imaging findings with clinical severity of the disease. Methods: One hundred consecutive patients, who presented with features suggestive of spinal infections, were subjected to MRI examination. T1W and STIR images were obtained followed by T2W and post-contrast T1W images. Various imaging characteristics of spinal infections were noted and correlated with the clinical severity of the disease. Results: Backache was the most common presenting symptom present in 86 %, while paraparesis was the most common sign seen in 62 %. The neurological status of the patients correlated well with MRI findings in the majority of the cases with an overall good correlation obtained in 96 % of cases. The majority of the vertebrae and intervertebral discs affected showed hypointensity or isointensity on T1W images and hyperintensity on T2W images. Epidural/dural disease was present in 74 % while 68 % of patients demonstrated decreased intervertebral disc height. Epidural extension and subligamentous spread was in 74 % and 90 % of patients respectively. Conclusions: MRI plays a vital role in early and accurate diagnosis of spinal infections. It is non-invasive and clearly demonstrates soft tissue anatomy and pathology which makes it superior to X-rays and Computed Tomography (CT). Imaging findings of tubercular spondylitis were also found to have a good correlation with the clinical status of the patients. Hence, it is of much help in the evaluation and assessment of patients presenting with features of spinal infections.  Keywords: Magnetic resonance imaging, spinal tuberculosis, tubercular spondylitis

Role of magnetic resonance imaging in evaluation of tubercular spondylitis: pattern of disease in 100 patients with review of literature

INTRODUCTION

The purpose of this study is to evaluate the role of magnetic resonance imaging (MRI) in evaluation of tubercular spondylitis and to correlate imaging findings with clinical severity of the disease.

METHODS

One hundred consecutive patients, who presented with features suggestive of spinal infections, were subjected to MRI examination. T1W and STIR images were obtained followed by T2W and post-contrast T1W images. Various imaging characteristics of spinal infections were noted and correlated with the clinical severity of the disease.

RESULTS

Backache was the most common presenting symptom present in 86 %, while paraparesis was the most common sign seen in 62 %. The neurological status of the patients correlated well with MRI findings in the majority of the cases with an overall good correlation obtained in 96 % of cases. The majority of the vertebrae and intervertebral discs affected showed hypointensity or isointensity on T1W images and hyperintensity on T2W images. Epidural/dural disease was present in 74 % while 68 % of patients demonstrated decreased intervertebral disc height. Epidural extension and subligamentous spread was in 74 % and 90 % of patients respectively.

CONCLUSIONS

MRI plays a vital role in early and accurate diagnosis of spinal infections. It is non-invasive and clearly demonstrates soft tissue anatomy and pathology which makes it superior to X-rays and Computed Tomography (CT). Imaging findings of tubercular spondylitis were also found to have a good correlation with the clinical status of the patients. Hence, it is of much help in the evaluation and assessment of patients presenting with features of spinal infections.

Functional outcome assessment after open tennis elbow release: what are the predictor parameters?

INTRODUCTION

Open surgical release remains the gold standard for treatment of recalcitrant lateral epicondylitis (tennis elbow). We aimed to evaluate the potential impact of perioperative factors on outcome after open surgical release for tennis elbow.

METHODS

All patients without elbow dislocation who underwent open surgical release for tennis elbow from January 2000 to June 2006 were included in the study. Comorbidities and associated pathologies of the upper limb as well as postoperative pain score, range of motion, evidence of instability, recurrence and other complications were noted.

RESULTS

There were 37 female and 24 male patients aged 22-60 (44.95 +/- 7.34) years. Five (8.1 percent) patients had diabetes mellitus. The mean duration of symptoms before surgery was 16.8 +/- 15.3 (range 2-84) months. The average duration of follow-up was 23.0 +/- 34.5 (range 0.4-206) months. Overall, 59 (96.7 percent) patients reported improvement of symptoms post surgery. Median grip strength on the operated and unoperated sides were 25.5 +/- 9.0 (range 10.5-44.0) KgN and 23.7 +/- 9.1 (range 9.3-41.5) KgN, respectively. Patients with diabetes mellitus had significantly higher pain scores (2.80 versus 0.36, p-value less than 0.01, 95 percent confidence interval [CI] 1.2-3.7), reduced grip strength (0.91 KgN versus 1.06 KgN, p-value is 0.038, 95 percent CI 0.29-0.01) and higher recurrence rates (40 percent versus 7.7 percent, p-value is 0.018).

CONCLUSION

Diabetes mellitus has a negative effect on surgical outcome in terms of pain scores, grip strength ratio and recurrence rate. This should be reiterated during preoperative counselling.

Protective potential of 17β-estradiol against co-exposure of 4-hydroxynonenal and 6-hydroxydopamine in PC12 cells

4-hydroxynonenal (4-HNE) and 6-hydroxydopamine (6-OHDA)-mediated damage in dopaminergic neurons is well documented. Protective potential of steroidal hormone (17β-estradiol) has also been suggested. However, therapeutic potential of such promising hormone is hampered due to complex brain anatomy and physiology. Thus, the present investigations were studied to suggest the applicability of dopamine expressing PC12 cells as in vitro tool to screen the pharmacological potential of 17β-estradiol against 4-HNE and 6-OHDA. MTT assay was conducted for cytotoxicity assessment of both 4-HNE (1 μM to 50 μM) and 6-OHDA (10-4 to 10-7 M). Non-cytotoxic concentrations, that is, 4-HNE (1 μM) and 6-OHDA (10-6 M) were selected to study the synergetic/additive responses. PC12 cells were found to be more vulnerable towards co-exposure of individual exposure of 4-HNE and 6-OHDA, even at non-cytotoxic concentrations. Then, cells were subjected to pre-treatment (24 hours) of 17β-estradiol (1 μM), followed by a permutation of combinations of both 4-HNE and 6-OHDA. Pretreatment of 17β-estradiol was found to be significantly effective against the cytotoxic responses of 4-HNE and 6-OHDA, when the damage was at lower level. However, 17β-estradiol was found to be ineffective against higher concentrations. Physiological-specific responses of PC12 cells against 4-HNE/6-OHDA and 17β-estradiol suggest its applicability as first tier of screening tool.

Association of dopamine DA-D2 receptor in rotenone-induced cytotoxicity in PC12 cells

The investigations were aimed to study the possible association of dopamine DA-D2 receptor in rotenone-induced cytotoxicity in PC12 cells, one among the most studied cell line in neurotoxicity studies. PC12 cells were subjected to receive an exposure of rotenone (10-6 to 10-4 M) for 24 and 48 hours. Cytotoxicity studies were carried out using standard end points including, (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) (MTT), lactate dehydrogenase (LDH) release and neutral red uptake (NRU). Cells were found to be vulnerable to rotenone in dose-dependent manner. In general, 10-4 and 10-5 M concentrations were found to be cytotoxic, whereas 10-6 M and lower concentrations used have shown nonsignificant effect on cell viability. Further, studies were extended to study the rotenone-induced alterations in cellular glutathione (GSH) level and dopamine DA-D2 receptor expression. Significant (p < 0.001) chronological depletion in GSH levels were recorded following rotenone exposure. Expression of dopamine DA-D2 receptor was also found to be effected significantly (p < 0.001) at 24 hours of rotenone exposure (10-4 and 10-5). However, no further depletion in the expression of dopamine DA-D2 receptor could be recorded with extended exposure period, that is, 48 hours. Rotenone at 10-6 M and lower concentrations was found to be ineffective in PC12 cells. Data suggest the vulnerability of PC12 cells against experimental exposure of rotenone, which possibly routed through dopamine DA-D2 receptor and oxidative stress machinery.

NGF induced differentiated PC12 cells as in vitro tool to study 4-hydroxynonenal induced cellular damage

Investigations were carried out to examine the suitability of PC12 cells as an in vitro tool to examine 4-hydroxynonenal (4-HNE)-induced toxicity in nervous tissue. On day 8 of differentiation, markers of neural effects and oxidative stress were measured following exposure of PC12 cells to 1-50 microM 4-HNE for 1-8h. Endpoints included dopamine DA-D(2) receptor and glutathione S-transferase (GSTP1-1) protein levels, 4-HNE-protein binding, glutathione (GSH) concentrations and intracellular calcium levels. GSH levels were maximally depleted after 4h. 4-HNE also induced depletion of GSTP1-1 and increased intracellular Ca(++), with the latter seen as early as 1h after exposure. Responses at 8h were not greater than responses at earlier times. The experiments suggest that PC12 cells could be an in vitro tool for understanding toxicant-cell interactions, especially those that result in oxidative stress.

Differential protection of pre-, co- and post-treatment of curcumin against hydrogen peroxide in PC12 cells

Pharmacological potential of curcumin was assessed in PC12 cells against hydrogen peroxide (H(2) O(2)) exposure. In MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] and lactate dehydrogenase (LDH) assays, 24-hour exposure of H(2)O(2) (0.5 mM and above) was found to be cytotoxic. A significant (p < 0.001) increase in percentage cell viability was recorded in PC12 cells pretreated with curcumin (25, 50 and 100 µg/mL) for 24 hours prior to H(2)O(2) (0.5 and 1 mM) exposure for 24 hours. Co-exposure to H(2)O(2) and curcumin was also found effective. However, a therapeutic treatment of curcumin for 24 hours after H(2)O(2) exposure to the cells was found ineffective. Differential response of PC12-H(2)O(2) model to curcumin in MTT and LDH assays suggests the utility of these endpoints to sort the drug candidates to study their antioxidant potential.

Azygos vein lead implantation for high defibrillation thresholds in implantable cardioverter defibrillator placement

Evaluation of defibrillation threshold is a standard of care during implantation of implantable cardioverter defibrillator. High defibrillation thresholds are often encountered and pose a challenge to electrophysiologists to improve the defibrillation threshold. We describe a case series where defibrillation thresholds were improved after implanting a defibrillation lead in the azygos vein.

Oxygen glucose deprivation model of cerebral stroke in PC-12 cells: glucose as a limiting factor

Optimum time points for oxygen-glucose deprivation (OGD) and re-oxygenation have been identified to suggest the suitability of PC-12 cells as rapid and sensitive in vitro model of cerebral stroke. Further, the precise role of glucose as one of the limiting factors was ascertained. PC-12 cells were subjected to receive OGD of 1-8 h followed by re-oxygenation for 6 to 96 h in medium having glucose 0-10 mg/ml. Loss of cell viability was assessed using trypan blue dye exclusion and MTT assays. The significant (p < 0.05) reduction in percent viable cell count was started at 2 h of OGD (80.7 +/- 2.0) and continued in further OGD periods (3, 4, 5, 6, 7, and 8 h), i.e. 65.7 +/- 3.5, 59.7 +/- 4.6, 54.3 +/- 3.2, 44.7 +/- 2.9, 20.3 +/- 4.3, 5.7 +/- 2.0 of counted cells, respectively. Cells growing in glucose-free medium have shown a gradual (p < 0.001) decrease in cell viability throughout the re-oxygenation. Re-oxygenation of 24 h was found to be first statistically significant time point for all the glucose concentrations. Glucose concentration during re-oxygenation was found to be one of the key factors involved in the growth and proliferation in PC-12 cells. The OGD of 6 h followed by a re-oxygenation period of 24 h with 4-6 mg/ml glucose concentration could be recorded as optimum conditions under our experimental conditions.

The relationship of transverse sinus stenosis to bony groove dimensions provides an insight into the aetiology of idiopathic intracranial hypertension

INTRODUCTION

Transverse sinus tapered narrowings are frequently identified in patients with idiopathic intracranial hypertension (IIH); however, it remains unclear whether they are primary stenoses or whether they occur secondary to raised cerebrospinal fluid pressure. Computed tomographic venography demonstrates both the morphology of the venous system and the adjacent bony grooves so it may provide an insight into the aetiology of these transverse sinus stenoses.

MATERIALS AND METHODS

Tapered transverse sinus narrowings (>50%) were studied in 19 patients without IIH and 14 patients with IIH. Computed tomography vascular studies were reviewed and the dimensions of the venous sinuses and bony grooves at the sites of maximum and minimum transverse sinus area dimensions were recorded.

RESULTS

There was demonstrated to be a strong correlation of bony groove height with venous sinus height at the largest portions of the transverse sinus in both IIH patients and non-IIH subjects as well as at the transverse sinus narrowing in non-IIH subjects. There was a discordant relationship between bony groove height and venous sinus height at the site of transverse sinus stenoses in IIH patients. In 5/23 IIH transverse sinus stenoses, the bony groove height was proportionate to that seen in non-IIH subjects. There were a further 8/23 cases where the small or absent sinus was associated with an absent bony groove.

CONCLUSION

Transverse sinus tapered narrowings in subjects without IIH and in the majority of patients with IIH were associated with proportionately small or absent grooves, and these are postulated to be primary or fixed. Some patients with IIH demonstrate tapered transverse sinus stenoses with disproportionately large bony grooves, suggesting a secondary or acquired narrowing. This implies a varied aetiology for the transverse sinus stenoses of IIH.

Inflammatory markers, insulin resistance and carotid intima-media thickness in North-Indian type 2 diabetic subjects

OBJECTIVE

To study the interrelationship of the inflammation, insulin resistance and atherosclerosis in recently diagnosed type 2 diabetes.

METHODOLOGY

Eighty-one newly diagnosed type 2 diabetic patients were compared with 81 healthy age, sex and BMI matched controls. Plasma glucose and insulin (fasting and after 2 hours of 75 gm of oral glucose), lipids and serum levels of C-reactive protein (CRP), fibrinogen and Tumour Necrosis Factor (TNF)-alpha were measured. Carotid (Intima-Medial Thickness) IMT was measured using high "resolution B-Mode ultrasonography. Insulin resistance was calculated using HOMA-IR model. Electrocardiogram (ECG) and exercise ECG were recorded for the evidence of coronary heart disease (CHD).

RESULTS

Carotid IMT was significantly thicker in diabetic patients than in control group across the whole age range (p < 0.01). In merged group of diabetes, composite IMT was significantly correlated with LDL-cholesterol, fasting insulin, serum cholesterol, BMI and HOMA-IR (p < 0.01). After controlling for age and sex, all glycaemic parameters were correlated with IMT in both diabetic and control group. HOMA-IR, waist hip ratio, serum triglycerides, serum cholesterol, fasting serum insulin and CRP were significant predictor of IMT. Concentrations of inflammatory markers were significantly higher in diabetic patients than in control group. Serum levels of CRP (p < 0.05) were found to be higher in diabetic patients with CHD than without CHD. CRP was significantly correlated with IMT (r = 0.603, p < 0.01) in diabetic subjects with and without CHD after controlling for age and sex.

CONCLUSION

Inflammatory markers are associated with type 2 diabetes but only CRP is associated with development of accelerated atherosclerosis and subsequent CHD.

Caudal anesthesia in pediatric surgical practice

Prospective study was carried out on 100 patients since May 2005 in my private practice and in the department of pediatric surgery of MMCH. Under caudal anesthesia along with or without ketaminie induction and gas inhalation all the patients underwent different surgical procedure namely anorectal surgery (eg. anoplasty, rectal polyp), urogenital surgery (Circumcision, hypospadias, meatotomy), groin surgery (hernia, hydrocele) and foot & leg surgery. Calculated dose schedule of drugs used in anesthesia and volume were maintained. Time of giving anesthesia and time of starting analgesia were recorded. Per-operative and postoperative analgesia were evaluated. Every parent was explained regarding the merit of caudal anesthesia calculated and compared with that of general anesthesia. Application of caudal anesthesia with or without ketamine & diazepam induction can be used safely and cost effectively and may be put into protocol in many of the pediatric surgical practice both in institute and also in private practice.

Treatment of non union of humerus using G. A. Ilizarov technique

The management of the non union of humerus is one of the most challenging problems that the surgeon confronts in his practice. The procedures traditionally used are: I.M. Nailing, interlocking, plating, transplantation of allograft. In our series, 36 cases with non union has been treated by G.A. Ilizarov technique. The age range were: 21-62 years with an average of 32 years. The initial treatment were done by DCP, rush nails & plates with screw fixation. The duration of treatment ranged from 5-11 months (average 8 months). With the application of Ilizarov fixator a good range of elbow & shoulder motion were achieved. The average follow up period was 5 years with a range of 1-8 years. Union was achieved in all the 36 cases.

Chemistry and anti-HIV properties of 2'-fluoro-2',3'-dideoxyarabinofuranosylpyrimidines

The synthesis, chemistry, biochemistry, and anti-HIV activity of a series of 1-(2,3-dideoxy-2-fluoro-beta-D-threopentofuranosyl)pyrimidines have been studied in an attempt to find useful anti-AIDS drugs. Synthesis is carried out via a 2,3-dideoxyribose intermediate which facilitates the preparation of analogues by removing the sugar 3'-hydroxyl group prior to, rather than after, condensation with a uracil or cytosine aglycon. The 2'-F-dd-uridine analogues 7a-d (with H, F, Cl, and CH3 substitution in the 5-position) as well as the 4-deoxy compound (12b) are nonprotective to ATH8 or CEM cells infected with HIV-1. In the corresponding cytidine series, the 5-chloro analogue (11) is inactive. However, 2'-fluoro-2',3'-dideoxyarabinosylcytosine, 10a, and its 5-fluoro analogue, 10b, are both active. While neither compounds is a potent as ddC or 5-F-ddC (2b), 10b gives complete protection against the cytopathic effects of HIV in both host cell lines. 2'-Fluoro substitution confers increased chemical and enzymatic stability on dideoxynucleosides. Even though dideoxy pyrimidine nucleosides are inherently more stable than the corresponding purine analogues toward acid-catalyzed cleavage of the glycosidic bond, 2'-fluoro substitution (10a) still increases stabilization relative to ddC (2b). No detectable deamination by partially purified cytidine deaminase is observed with the 2'-fluoro compounds 10a, 10b, or 11 under conditions which rapidly deaminate cytidine. A small amount of 2'-F-dd-ara-U (7a) is formed from 10a in monkey plasma after greater than 24 h of exposure. The octanol-water partition coefficients for the dideoxynucleosides in this study indicate their hydrophilic character, with log P values varying from -0.28 to -1.18.

Effect of prenatal doxycycline administration on skeletal differentiation in long bones of Albino rat

OBJECTIVE

To study the teratogenic risk of Doxycycline administration during gestation on skeletal differentiation.

DESIGN

An animal study carried out on experimental Albino rat.

SETTING

The study was carried out in the Department of Anatomy Basic Medical Sciences Institute, Jinnah Postgraduate Medical Centre (JPMC), Karachi from June 1999 to May 2000.

METHODS

Doxycycline was given to pregnant female Albino rats in a dose of 8 mg/kg intraperitoneally from day 8th to 19th of gestation. The intact rat fetuses were isolated on days 15th to 19th of gestation and pups on 1st postnatal day. These animals were then killed by deep ether anesthesia and fixed in 80% alcohol. They were then bulk stained with alizarin red S and alcian blue. Finally they were cleared in 4% KOH and stored in glycerin. The fore and hind limbs were disarticulated from the axial skeleton and observed under stereomicroscope for evidence of skeletal differentiation in the form of presence of primary ossification centers in long bones. The time of appearance of these centers were noted and compared statistically with those in the control animals.

RESULTS

The study revealed that the skeletal differentiation in long bones was delayed in experimental animals as compared with controls.

CONCLUSION

Doxycycline administration during pregnancy presents a risk to skeletal differentiation and therefore to its growth.

Predominance of the DEN-3 genotype during the recent dengue outbreak in Bangladesh

A recent outbreak of dengue in Bangladesh was marked by many fatal complications. As clinical virulence varies among the genotypes of dengue virus, a study was conducted to investigate the molecular genotypes of dengue in Bangladesh. Reverse transcription polymerase chain reaction was used to determine viral genotypes using oligonucleotide generic primers that produce a 511 bp product. The resulting product was typed by nested PCR with strain-specific primers, yielding 482 (DEN-1), 119 (DEN-2), 290 (DEN-3) and 392 (DEN-4), visualized on UV transilluminator after electrophoresis on 2% agarose gel stained with ethidium bromide. Of 45 clinically diagnosed dengue patients (mean age 28 years; male/female 30/15), 19 (42.2%) had detectable viral RNA in their blood. However, during the first 5 days of fever in 30 patients, the frequency was 60% (18/30), implying that the sooner serum is drawn after the fever, the greater the chances of detecting viral RNA. DEN-3 was detected in all except 2 patients who were infected with DEN-2. DEN-2 (two cases) and DEN-4 (one case) were present as co-infections with DEN-3. All of the patients presented with fever, anorexia and vomiting; many had headache and general body ache; a few had a rash. About a quarter had suffered episodes of bleeding, while ascites, pleural effusion and CNS symptoms were found in a few patients Patients positive for viral RNA were also positive for anti-dengue IgM (p=0.007) in subsequent sampling. The study suggests the predominance of DEN-3 infection with occasional co-infection with other types, during the recent outbreak of dengue in Bangladesh.

Differential effects of doxorubicin on atrial natriuretic peptide expression in vivo and in vitro

Doxorubicin (Dox) is a potent anti-cancer agent with cardiotoxic side-effects but the mechanism of its cardiotoxicity and its effect on expression of the vasoactive atrial natriuretic peptide (ANP), an important marker for cardiac hypertrophy, are little understood. The present study examined Dox-induced changes in vivo in hearts of 6 mongrel dogs and 5 Sprague-Dawley rats and in vitro in cardiac cultures of neonatal rats. Quantitative RT-PCR analysis using gamma 32-p labeled primers for beta-actin, phospholamban (PLB) and ANP showed a selective 5-fold increase of ANP mRNA in Dox-treated dog hearts in comparison to controls. Similarly, northern analysis of GAPD, beta-actin, cardiac alpha-actin and ANP gave a selective 4.5-fold increase in ANP transcripts in Dox-treated rat hearts. On the other hand, there was a selective decrease (approximately 39%) of ANP transcripts in Dox-treated cardiac cultures relative to controls. Immunohistochemistry localized the ANP changes both in tissue sections and in cultures to the cardiomyocytes. The data clearly showed that Dox selectively increases ANP expression in dog and rat hearts in absence of cardiocyte hypertrophy but selectively decreases it in cardiac cultures. This differential effect of Dox on cardiocytes in vivo and in vitro should be a useful parameter for studies of transcriptional control of ANP expression.

Novel bicyclic lactam inhibitors of thrombin: potency and selectivity optimization through P1 residues

Peptidomimetic inhibitors of thrombin lacking the important Ser195-carbonyl interaction have been prepared. The binding energy lost after the removal of the activated carbonyl was recaptured through a series of modifications of the P1 residues of the bicyclic lactam inhibitors. Selected substituted compounds displayed useful pharmacological profiles both in vitro and in vivo.

Response to hypoxia involves transforming growth factor-beta2 and Smad proteins in human endothelial cells

Oxygen deprivation (hypoxia) is a consistent component of ischemia that induces an inflammatory and prothrombotic response in the endothelium. In this report, it is demonstrated that exposure of endothelial cells to hypoxia (1% O(2)) increases messenger RNA and protein levels of transforming growth factor-beta2 (TGF-beta2), a cytokine with potent regulatory effects on vascular inflammatory responses. Messenger RNA levels of the TGF-beta2 type II membrane receptor, which is a serine threonine kinase, also increased. The stimulatory effect of hypoxia was found to occur at the level of transcription of the TGF-beta2 gene and involves Smad proteins, a class of intracellular signaling proteins that mediates the downstream effects of TGF-beta receptors. Transient transfection studies showed that the region spanning -77 and -40 base pairs within the TGF-beta2 promoter (harboring a Smad-binding "CAGA box") is activated in hypoxic cells compared with nonhypoxic controls (P <.01). Hypoxia also stimulated transcription from another promoter, 3TP-Lux, a reporter construct responsive to Smads and TGF-beta. In addition, specific binding to a Smad-binding oligonucleotide was observed with nuclear extracts from hypoxic endothelial cells but not from nonhypoxic cells. It is concluded that Smad proteins, which can regulate endothelial responses to mechanical and inflammatory stress, also may play an important role in vascular responses to hypoxia and ischemia.

Role of STAT3 in ischemic preconditioning

We recently demonstrated that ischemic preconditioning (IPC) induced by cyclic episodes of short durations of ischemia and reperfusion potentiates a signal transduction cascade involving protein tyrosine kinases and MAP kinases. A rapid activation of janus kinase (JAK) and several signal transducers and activators of the transcription (STATs) including STAT3, STAT5A and STAT6 has been shown to occur during myocardial ischemia and reperfusion. This study sought to examine if JAK/STAT signaling pathway play any role in classical early phase of IPC. Isolated working rat hearts were perfused for 15 min with KHB buffer in the absence or presence of a JAK kinase inhibitor tyrphostin AG490 (5 microm) followed by IPC, 30 min global ischemia and 2 h of reperfusion. The results demonstrated extensive phosphorylation of JAK2 and STAT3 in the IPC hearts which was almost completely abolished by an inhibitor of JAK2, AG490. IPC displayed cardioprotection as evidenced by improved post-ischemic contractile recovery, decreased myocardial infarct size and reduced number of apoptotic cardiomyocytes. AG490 blocked IPC-mediated cardioprotection by altering the IPC-mediated survival signal into death signal. Thus, IPC-induced upregulation of antiapoptotic gene bcl-2 and downregulation of pro-apoptotic gene bax are decreased and increased, respectively, in the AG490 treated hearts. The results suggest that early phase of IPC potentiates JAK/STAT signaling by activating STAT3 which transmits a survival signal to the myocardium.

Ventricular myosin light chain-2 gene expression in developing heart of chicken embryos

Recent gene knock-out studies in mice have suggested that ventricular myosin light chain-2 (vMLC2) has a role in the regulation of cardiogenic development and that perturbation in expression of vMLC2 is linked to the onset of dilated cardiomyopathy. In an attempt to develop an avian model for such studies, we examined the expression pattern of vMLC2 in chicken embryos at various stages and analyzed the effect of antisense oligonucleotide-mediated interference of vMLC2 function in cultures of whole embryos. Our results showed vMLC2 to be a specific marker for ventricular chamber throughout chicken embryonic development and antisense vMLC2 treatment of primitive streak stage (stage 4) embryos to produce pronounced dilation of heart tube with severe deficiency in formation of striated myofibrils. Further studies with antisense mRNA techniques of whole embryo cultures should, therefore, be useful to evaluate the role of vMLC2 and other putative regulatory factors in cardiac myofibrillogenesis.

JAK/STAT signaling is associated with cardiac dysfunction during ischemia and reperfusion

BACKGROUND

Activation of the heart renin-angiotensin system (RAS) under pathophysiological conditions has been correlated with the development of ischemic injury. The binding of angiotensin II to its receptors triggers induction of several, perhaps multifunctional, intracellular signaling pathways, notable among them the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway. In this study, we investigated whether the JAK/STAT signaling is involved in the ischemia/reperfusion injury in adult rat myocardium.

METHODS AND RESULTS

We report here that 2 components of the JAK/STAT signaling pathway, namely STAT 5A and STAT 6, are selectively activated in the rat heart subjected to ischemia/reperfusion. The activated STATs bind to a conserved nucleotide sequence (St domain) in the promoter of the angiotensinogen (ANG) gene and consequently upregulate the level of ANG mRNA. Treatment of the hearts with losartan (4.5 micromol/L), an AT(1) blocker, or with tyrphostin AG490 (5 micromol/L), an inhibitor of JAK 2 phosphorylation, results in loss of the STAT/ANG promoter binding activity and an upregulated level of ANG mRNA. Hearts treated with the JAK 2 inhibitor tyrphostin AG490 showed a reduction in myocardial infarct size and in number of cardiomyocytes undergoing apoptosis. The treated hearts also showed a recovery in functional hemodynamics of the myocardium.

CONCLUSIONS

These findings suggest that activation of the JAK/STAT signaling pathway is a significant contributing factor to the pathogenesis of myocardial ischemia and that interference in activation of the pathway potentiates recovery in cardiac function.

Interventional therapy for acute myocardial infarction

Percutaneous transluminal coronary angioplasty has proven to be more effective and safer than thrombolytic therapy for the treatment of acute ST elevation myocardial infarction. Coronary intervention decreases early mortality and the incidence of intracerebral hemorrhage when performed by an experienced interventional team in a timely fashion. After failed fibrinolytic therapy for myocardial infarction, percutaneous transluminal coronary angioplasty is indicated for signs of ischemia and is very effective in restoring vessel patency and reducing mortality when used as a rescue procedure. The glycoprotein IIb-IIIa inhibitors improve outcomes in percutaneous transluminal coronary angioplasty, particularly in patients undergoing stent placement. Percutaneous interventional therapy in acute myocardial infarction is particularly beneficial in patients with cardiogenic shock and effective for saphenous vein graft occlusions, patients with diabetes mellitus, and in the elderly. New devices and drugs are currently being tested for acute myocardial infarction and provide hope for even better interventional therapies in the near future.

Anabolic-androgenic steroids induce apoptotic cell death in adult rat ventricular myocytes

We tested whether exposure to anabolic-androgenic steroids (AASs) would induce apoptosis in adult rat ventricular myocytes in vitro. Myocytes were exposed to stanozolol (STZ), testosterone enanthate (TE) and testosterone (T) (0.1 micromol/L, 1 micromol/L, 10 micromol/L, and 100 micromol/L) for 20 h. The percentage of myocytes undergoing apoptosis was determined by terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) and was found to be increased when compared to control myocytes at STZ 10 micromol/L 12 +/- 2% (mean +/- SD), STZ 100 micromol/L 42 +/- 3%; TE 1 micromol/L 11 +/- 2%, TE 10 micromol/L 21 +/- 3%, TE 100 micromol/L 62 +/- 2%; T 10 micromol/L 11 +/- 2%, T 100 micromol/L 40 +/- 3% (P < 0.001 vs. CTL 2 +/- 2%). The STZ-, TE- and T-induced dose-dependent apoptotic cell death was corroborated by a significantly increased DNA laddering in myocytes exposed to STZ and T > or = 10 micromol/L and TE > or = 1 micromol/L. Notably, STZ, TE, and T exposure markedly increased the expression of the pro-apoptotic oncogene Bax-alpha, as assessed by reverse transcription-polymerase chain reaction. Taken together, these results clearly show for the first time that AASs induce apoptotic cell death in a dose-dependent manner. This finding may have important implications in understanding the pathogenesis of ventricular remodeling, cardiomyopathy, and sudden cardiac death associated with AAS abuse.

Anabolic-androgenic steroids induce apoptotic cell death in adult rat ventricular myocytes

We tested whether exposure to anabolic-androgenic steroids (AASs) would induce apoptosis in adult rat ventricular myocytes in vitro. Myocytes were exposed to stanozolol (STZ), testosterone enanthate (TE) and testosterone (T) (0.1 micromol/L, 1 micromol/L, 10 micromol/L, and 100 micromol/L) for 20 h. The percentage of myocytes undergoing apoptosis was determined by terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) and was found to be increased when compared to control myocytes at STZ 10 micromol/L 12 +/- 2% (mean +/- SD), STZ 100 micromol/L 42 +/- 3%; TE 1 micromol/L 11 +/- 2%, TE 10 micromol/L 21 +/- 3%, TE 100 micromol/L 62 +/- 2%; T 10 micromol/L 11 +/- 2%, T 100 micromol/L 40 +/- 3% (P < 0.001 vs. CTL 2 +/- 2%). The STZ-, TE- and T-induced dose-dependent apoptotic cell death was corroborated by a significantly increased DNA laddering in myocytes exposed to STZ and T > or = 10 micromol/L and TE > or = 1 micromol/L. Notably, STZ, TE, and T exposure markedly increased the expression of the pro-apoptotic oncogene Bax-alpha, as assessed by reverse transcription-polymerase chain reaction. Taken together, these results clearly show for the first time that AASs induce apoptotic cell death in a dose-dependent manner. This finding may have important implications in understanding the pathogenesis of ventricular remodeling, cardiomyopathy, and sudden cardiac death associated with AAS abuse.

Early developmental expression pattern of retinoblastoma tumor suppressor mRNA indicates a role in the epithelial-to-mesenchyme transformation of endocardial cushion cells

The earliest stages of embryonic development are characterized by the generation of precursor cell populations that differentiate and coalesce into tissue and organ primordia. To provide sufficient numbers of differentiated cells for tissue and organ formation, the differentiative as well as the proliferative processes of cells must be controlled and coordinated. Potential regulators of the proliferative process include molecules that control the cell cycle, in particular, the tumor suppressor proteins. To begin to understand the role such molecules can play in development, we have studied the expression of the retinoblastoma tumor suppressor (Rb) gene in early chicken development. Our studies in early chicken embryos show that Rb is encoded by a single gene that gives rise to several Rb mRNA isoforms through alternative splicing of a primary transcript. These mRNA isoforms potentially encode Rb proteins that differ with respect to the number of sequence motifs known to target cyclin-dependent kinases to Rb, suggesting dynamic control of Rb phosphorylation and function during development. This complex expression pattern of Rb mRNA begins as early as the blastoderm stage of chicken development (stage 3) and continues through stage 18, the latest stage examined. Despite this early embryonic expression of Rb mRNA as detected by reverse transcription polymerase chain reaction, Rb mRNA levels sufficient to be detected by in situ hybridization were not expressed until after stage 14 of development. Rb mRNA was found to be localized to cells of the endocardial cushions of the early heart tube, cells of the epicardium, and myogenic cells of the somitic myotome. Interestingly, each of these cell types undergoes an epithelial-to-mesenchyme transformation to form a migratory and/or invasive population of mesenchymal cells. We have focused our studies on the expression of Rb mRNA in endocardial cells of the early heart tube, because the transition of these cells to mesenchyme initiates the important process of septation, an early step in the formation of heart valves.

Potent and selective bicyclic lactam inhibitors of thrombin. Part 4: transition state inhibitors

Bicyclic piperazinone based thrombin inhibitors of general structure 2 were prepared and evaluated in vitro and in vivo. These inhibitors, having in common an electrophilic basic trans-cyclohexylamine P1 residue, displayed high thrombin affinity, high selectivity against trypsin and good in vivo efficacy in the rat arterial thrombosis model.

Modulation of MLC-2v gene expression by AP-1: complex regulatory role of Jun in cardiac myocytes

Hypertrophic stimulation of cardiac myocytes results in rapid induction of a number of transcription factors, including members of the AP-1 family, which is followed by a programmed alteration in the pattern of gene expression. In the ventricular cardiocytes there is re-expression of the fetal atrial natriuretic factor (ANF) gene and upregulation of its myosin light chain-2 (MLC-2v). The mechanism(s) by which the induction ofAP-1 is coupled to the promoters of these target genes is largely unknown. In this report, we demonstrate that in transient co-transfection assay, c-Jun inhibited while Jun B stimulated the MLC-2v promoter activity. Mutant c-Jun recombinants, in which the activation domains were deleted, still remained inhibitory, but a specific mutation in the leucine zipper, which changes the alignment of Jun with its dimerization partner, caused a reversal of its effect on the target MLC-2v promoter. Based on these findings, we propose that in chicken cardiac myocytes, the regulation of MLC-2v promoter by Jun may occur via its interaction with other proteins, possibly of the leucine zipper family.

Parallel synthesis of isatin-based serine protease inhibitors

The synthesis of N-functionalised isatins using parallel, solution synthesis is described. Functionalised polymers were employed as stoichiometric and catalytic reagents as well as purification media in the exercise, and the derivatives were screened against a panel of serine proteases; high percentage inhibition was observed in several cases.

In vitro and in vivo properties of bicyclic lactam inhibitors: a novel class of low molecular weight peptidomimetic thrombin inhibitors

We have developed potent and selective thrombin inhibitors with a novel non-peptidic structure. A bicyclic lactam was used as the scaffold on which various P1 and P3 motifs were substituted. Herein, we report the in vitro and in vivo properties of four representatives of this novel class of inhibitors. Their Ki values were less than 10 nM, they inhibited equally both free and clot-bound thrombin, and they displayed high level of specificity for thrombin over other serine proteases (trypsin, factor Xa, activated Protein C, and plasmin). They prolonged the clotting time of human plasma to twice the control value in coagulation assays (TT, APTT, and PT) at a concentration below 3 microM. Their anticoagulant activities using rat plasma were similar to, although slightly weaker, than with human plasma. Furthermore, they inhibited thrombin-induced platelet aggregation (human and rat) at concentrations close to their Ki values for thrombin. These molecules demonstrated similar dose response antithrombotic efficacy in rat arterial and venous thrombosis models when given as i.v. bolus followed by infusion. Antithrombotic efficacy of 85% and greater was observed at a dose of 5-7 microM/kg/hour in each model. Bicyclic lactam inhibitor 3, at a dose which caused a complete inhibition of visible thrombus formation in the venous and arterial models of thrombosis, showed a 1.9-2.1 and a 4.0-4.8-fold shift in APTT and TT, respectively. Unfortunately, the bicyclic lactam inhibitors exhibited low oral bioavailability in rats. Therefore, this novel class of bicyclic lactam thrombin inhibitor has the potential to be promising intravenous antithrombotic agents for the treatment of arterial as well as venous thrombosis and warrants further investigation.

Chick homeobox gene cDlx expression demarcates the forebrain anlage, indicating the onset of forebrain regional specification at gastrulation

Here we describe the isolation and characterization of a chick homeobox-containing gene, cDlx, which shows greater than 85% homology to the homeodomain of other vertebrate Distal-less genes. Northern blot analysis and in situ hybridization studies reveal that cDlx expression is developmentally regulated and is tissue specific. In particular, the developmental expression pattern is characterized by an early appearance of cDlx transcript in the prospective forebrain region of gastrulating embryos. During neurulation, cDlx is consistently expressed in a spatially restricted domain in the presumptive ventral forebrain region of the neural plate that will give rise to the hypothalamus and the adenohypophysis. Our data support the notion that members of the Dlx gene family are part of a homeobox gene code in forebrain pattern formation and suggest that regional specification of the forebrain occurs at much earlier stages than previously thought. The homeobox gene cDlx may thus play a role in defining forebrain regional identity as early as gastrulation.

Interactions of conformationally biased north and south 2'-fluoro-2', 3'-dideoxynucleoside 5'-triphosphates with the active site of HIV-1 reverse transcriptase

Molecular dynamics simulations of a ternary complex of HIV-1 reverse transcriptase (RT), double-stranded DNA, and bound dideoxynucleoside-5'-triphosphate (RT-DNA-ddNTP), utilizing the ddNTPs ddATP, betaFddATP, and alphaFddATP, explain the experimentally observed order of potency of these 5'-triphosphates as inhibitors of RT: ddATP > betaFddATP > alphaFddATP. On the basis of RT's known preference to bind the incoming dNTP (or ddNTP) with a north conformation at the polymerase site, alphaFddATP, which in solution prefers almost exclusively a north conformation, was predicted to be the most potent inhibitor. However, Tyr115, which appears to function as a steric gate to preclude the binding of ribonucleoside 5'-triphosphates, prevents the effective binding of alphaFddATP in its preferred north conformation. The south-biased betaFddATP, while able to bind to RT without hindrance by Tyr115, has to pay a high energy penalty to be flipped to the active north conformation at the polymerase site. Finally, the more flexible and less conformationally biased ddATP is able to switch to a north conformation at the RT site with a smaller energy penalty than betaFddATP. These results highlight the opposite conformational preferences of HIV-1 RT for alphaFddATP and betaFddATP and help establish conformational guidelines for optimal binding at the polymerase site of this enzyme.

The role of Jak/STAT signaling in heart tissue renin-angiotensin system

The involvement of the Renin Angiotensin System (RAS) and the role of its primary effector, angiotensin II (Ang II), in etiology of myocardial hypertrophy and ischemia is well documented. In several animal models, the RAS is activated in cardiac cell types that express the receptor AT1, and/or AT2, through which the Ang II mediated effects are promoted. In this article, we briefly review recent experimental evidence on the critical role of a prominent signaling pathway, the Jak/STAT pathway in activation and maintenance of the local RAS in cardiac hypertrophy and ischemia. Recent studies in our laboratory document that the promoter of the prohormone angiotensinogen (Ang) gene serves as the target site for STAT proteins, thereby linking the Jak/STAT pathway to activation of heart tissue autocrine Ang II loop. STAT5A and STAT6, are selectively activated when the heart is subjected to ischemic injury, whereas activation of STAT3 and STAT5A is involved in myocardial hypertrophy. Blockage of RAS activation by treatment with specific inhibitor promotes a remarkable recovery in functional hemodynamics of the myocardium. Thus, activation of selective sets of STAT proteins constitutes the primary signaling event in the pathogenesis of myocardial hypertrophy and ischemia.

Prevalence of infectious diseases and drug abuse among Bangladeshi workers

Individuals seeking jobs abroad need health fitness certificates before entering into those countries. Medical screening of 43,213 Bangladeshi job seekers (M/F: 42,290/923) was carried out in our reference center during the period August, 1994 to May, 1996. Albeit male predominance, they represented middle and lower middle socio-economic class of the population from all over the country. All were young adults (age: 27.05+/-3.56 years; mean+/-SD) applying for job visas to different Asian countries. Physical examination and laboratory investigations including markers for several infectious diseases and drugs of abuse were carried out as required by countries recruiting the workers. Serological tests revealed that 1,884 (4.4%) of individuals were positive for hepatitis B surface antigen (HBsAg), 737 (1.7%) for Treponema pallidum hemagglutination (TPHA) and only 83 (0.2%) for antibody to human immunodeficiency virus (anti-HIV). However, we could not confirm any case of infection with HIV. Chest X-ray suggestive of pulmonary tuberculosis was found in 162 (0.4%) and on blood film, malarial parasites could be observed only in 4 cases. Their urine analysis revealed the presence of opiates or cannabinoids in 471 (1.1%) individuals. HBsAg-positive cases (p = 0.003) and abuse of opiates (p = 0.024) or cannabinoids (p = 0.002) were significantly higher among males. TPHA reactivity and chest X-ray suggestive of tuberculosis were found to be higher among opiates (p = 0.002 and 0.027) and cannabinoids (p = 0.000 for both) abused as well as with increasing age (p = 0.000). These results may represent a cross-sectional view of the prevalence of different infectious diseases and abuse of drugs among the young adult population of Bangladesh.

Beta-adrenergic receptor subtypes differentially affect apoptosis in adult rat ventricular myocytes

BACKGROUND-Catecholamine-induced apoptosis is mediated by activation of the beta-adrenergic signaling pathway. We tested the hypothesis that beta(1)- and beta(2)-adrenergic receptor (AR) subtypes differentially affect apoptosis in adult rat ventricular myocytes in vitro. METHODS AND RESULTS-Myocytes were first exposed to norepinephrine (NE) alone (10 mcmol/L) or NE+atenolol (AT) (10 mcmol/L) for 12 hours. AT, a beta(1)-selective AR antagonist, abolished the NE-induced increase in nick end-labeling (TUNEL)-positive cells compared with control (NE, 33+/-3% versus control, 3+/-1%, P<0.0001; NE+AT, 4+/-2% versus control, 3+/-1%, P=0. 98). Annexin V staining, DNA laddering, and caspase activity determinations corroborated these results. Subsequent experiments under prazosin treatment established the apoptosis dose-response curves for the increasingly beta(2)-selective AR agonists isoproterenol (ISO) (beta(1) approximately beta(2)) and albuterol (ALB) (beta(2)>beta(1)). ISO and ALB induced significantly less apoptosis than NE (beta(1)>beta(2)) at equimolar concentrations as assessed by TUNEL staining [1 mcmol/L: NE (8+/-2%) approximately ISO (7+/-1%)>ALB (2+/-1%); 10 mcmol/L: NE (35+/-2%)>ISO (23+/-1%)>ALB (3+/-1%); 100 mcmol/L: NE (50+/-2%)>ISO (29+/-2%)>ALB (14+/-1%), P<0.0001 except for NE versus ISO at 1 mcmol/L with P=0.62]. ALB-induced apoptosis at 100 mcmol/L was abolished by AT (10 mcmol/L), indicating a beta(1)AR-mediated effect. Importantly, ICI 118551 (0.1 mcmol/L), a highly selective beta(2)AR antagonist, did not decrease the percentage of NE-, ISO-, and ALB-induced apoptosis. Reverse transcription-polymerase chain reaction studies revealed that AT completely reversed the beta-adrenergic signaling-induced changes in the Bcl-2-to-Bax ratio. CONCLUSIONS-These observations provide evidence that beta AR-mediated apoptotic death signaling is largely dissociated from beta(2)ARs and selectively mediated by beta(1)ARs in adult rat ventricular myocytes.

Norepinephrine-induced apoptosis is inhibited in adult rat ventricular myocytes exposed to volatile anesthetics

BACKGROUND

Volatile anesthetics are used to provide anesthesia to patients with heart disease under heightened adrenergic drive. The purpose of this study was to test whether volatile anesthetics can inhibit norepinephrine (NE)-induced apoptosis in cardiomyocytes.

METHODS

Rat ventricular cardiomyocytes were exposed to NE (10 microm) alone or in the presence of increasing concentrations of isoflurane and halothane.

RESULTS

Isoflurane at 1.6 minimum alveolar concentration (MAC) (4 +/- 2% [SD]) and halothane at 1.2 MAC (3 +/- 2%) abolished the percentage of cardiomyocytes undergoing NE-induced apoptosis (34 +/- 8%), as assessed by terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) (P < 0.0001). Lower concentrations of isoflurane and halothane markedly decreased the number of TUNEL-positive cells. Similarly, isoflurane at 1.6 MAC (5 +/- 3%) and halothane at 1.2 MAC (6 +/- 3%) prevented the increase in annexinV-staining cardiomyocytes (38 +/- 7%; P < 0. 0001). These findings were corroborated with a decreased quantity of NE-induced DNA laddering by volatile anesthetics. Halothane at 1.2 MAC abolished the increase in TUNEL-positive cardiomyocytes exposed to the dihydropyridine Ca2+-channel agonist BAY K-8644 (1 microm) (BAY K-8644 + halothane: 3 +/- 2% vsBAY K-8644: 34 +/- 6%; P < 0. 0001) and the Ca2+-ionophore 4-bromo-A23187 (1 microm) (4-bromo-A23187 + halothane: 2 +/- 2% vs4-bromo-A23187: 13 +/- 4%; P = 0.03). NE treatment increased caspase-9 activity to 197 +/- 62% over control myocytes (P < 0.0001), whereas no caspase-8 activation was detectable. This increase in caspase-9 activity was blocked by isoflurane at 1.6 MAC and halothane at 1.2 MAC.

CONCLUSIONS

Volatile anesthetics offer significant protection against beta-adrenergic apoptotic death signaling in ventricular cardiomyocytes. The authors present evidence that this protection is mainly mediated through modulation of cellular Ca2+ homeostasis and inhibition of the apoptosis initiator caspase-9.

Hepatitis C viral IRES inhibition by phenazine and phenazine-like molecules

An in vitro assay based on the expression of Fluci reporter gene under the translational control of HCV IRES was used to evaluate and screen compound libraries. A structure-activity relationship study on a phenazine hit was conducted. Our data suggest that an intact phenazine or phenazine-like core with two distal polar substitutions is crucial for potency.

Methanocarba analogues of purine nucleosides as potent and selective adenosine receptor agonists

Adenosine receptor agonists have cardioprotective, cerebroprotective, and antiinflammatory properties. We report that a carbocyclic modification of the ribose moiety incorporating ring constraints is a general approach for the design of A(1) and A(3) receptor agonists having favorable pharmacodynamic properties. While simple carbocyclic substitution of adenosine agonists greatly diminishes potency, methanocarba-adenosine analogues have now defined the role of sugar puckering in stabilizing the active adenosine receptor-bound conformation and thereby have allowed identification of a favored isomer. In such analogues a fused cyclopropane moiety constrains the pseudosugar ring of the nucleoside to either a Northern (N) or Southern (S) conformation, as defined in the pseudorotational cycle. In binding assays at A(1), A(2A), and A(3) receptors, (N)-methanocarba-adenosine was of higher affinity than the (S)-analogue, particularly at the human A(3) receptor (N/S affinity ratio of 150). (N)-Methanocarba analogues of various N(6)-substituted adenosine derivatives, including cyclopentyl and 3-iodobenzyl, in which the parent compounds are potent agonists at either A(1) or A(3) receptors, respectively, were synthesized. The N(6)-cyclopentyl derivatives were A(1) receptor-selective and maintained high efficacy at recombinant human but not rat brain A(1) receptors, as indicated by stimulation of binding of [(35)S]GTP-gamma-S. The (N)-methanocarba-N(6)-(3-iodobenzyl)adenosine and its 2-chloro derivative had K(i) values of 4.1 and 2.2 nM at A(3) receptors, respectively, and were highly selective partial agonists. Partial agonism combined with high functional potency at A(3) receptors (EC(50) < 1 nM) may produce tissue selectivity. In conclusion, as for P2Y(1) receptors, at least three adenosine receptors favor the ribose (N)-conformation.