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.

Frequency of tracheobronchial foreign bodies in children and adolescents

OBJECTIVE

The problem of foreign body aspiration in the community has been studied and compared with other reports.

METHODS

We have retrospectively studied patients who had bronchoscopy for suspected foreign bodies in the tracheobronchial tree, attending or referred to Al-Noor Specialist Hospital, Makkah over a period of 3 years from May 1996 to May 1999.

RESULTS

The total number of patients was 94 (62 male and 32 female). Ages ranged from 4 months to 45 years(mean age 3.77 years), 85% of children being under the age of 5 years. One hundred bronchoscopies (6 repeat bronchoscopies) and one thoracotomy were carried out. Foreign bodies were removed from 60 patients (64%). Six (10%) did not have any definite history, while 15 patients (21%) with definite history of foreign body aspiration had negative bronchoscopy. An aspirated Fis-Fis (Alfalfa, Lucerne) seed accounted for more than one-third of all foreign bodies. The most frequent symptoms, signs, radiological findings and site of foreign body lodgement in the tracheobronchial tree are discussed.

CONCLUSION

We conclude that a negative history, clinical examination and chest x-ray do not necessarily exclude aspirated foreign body material. Bronchoscopy is the most effective diagnostic and therapeutic modality to prevent complications related to neglected foreign body aspiration. In addition to children, teenagers and adolescents are also not immune to this problem. We recommend early referral to an appropriate hospital on suspicion or if symptoms persist. However, preventive measures, remain the best means of protecting these children.

Adenosine deaminase prefers a distinct sugar ring conformation for binding and catalysis: kinetic and structural studies

Several recent X-ray crystal structures of adenosine deaminase (ADA) in complex with various adenosine surrogates have illustrated the preferred mode of substrate binding for this enzyme. To define more specific structural details of substrate preferences for binding and catalysis, we have studied the ADA binding efficiencies and deamination kinetics of several synthetic adenosine analogues in which the furanosyl ring is biased toward a particular conformation. NMR solution studies and pseudorotational analyses were used to ascertain the preferred furanose ring puckers (P, nu(MAX)) and rotamer distributions (chi and gamma) of the nucleoside analogues. It was shown that derivatives which are biased toward a "Northern" (3'-endo, N) sugar ring pucker were deaminated up to 65-fold faster and bound more tightly to the enzyme than those that preferred a "Southern" (2'-endo, S) conformation. This behavior, however, could be modulated by other structural factors. Similarly, purine riboside inhibitors of ADA that prefer the N hemisphere were more potent inhibitors than S analogues. These binding propensities were corroborated by detailed molecular modeling studies. Docking of both N- and S-type analogues into the ADA crystal structure coordinates showed that N-type substrates formed a stable complex with ADA, whereas for S-type substrates, it was necessary for the sugar pucker to adjust to a 3'-endo (N-type) conformation to remain in the ADA substrate binding site. These data outline the intricate structural details for optimum binding in the catalytic cleft of ADA.

Structural basis of the thrombin selectivity of a ligand that contains the constrained arginine mimic (2S)-2-amino-(3S)-3-(1-carbamimidoyl- piperidin-3-yl)-propanoic acid at P1

We have studied the thrombin and trypsin complexed structures of a pair of peptidomimetic thrombin inhibitors, containing different P1 fragments. The first has arginine as its P1 fragment, and the second contains the constrained arginine mimic (2S)-2-amino-(3S)-3-(1-carbamimidoyl-piperidin-3-yl)-propano ic acid (SAPA), a fragment known to enhance thrombin/trypsin selectivity of inhibitors. On the basis of an analysis of the nonbonded interactions present in the structures of the trypsin and thrombin complexes of the two inhibitors, the calculated accessible surfaces of the enzymes and inhibitors in the four complexes, data on known structures of trypsin complexes of inhibitors, and factor Xa inhibitory potency of these compounds, we conclude that the ability of this arginine mimic to increase thrombin selectivity of an inhibitor is mediated by its differential interaction with the residue at position 192 (chymotrypsinogen numbering). Thrombin has a glutamic acid at residue 192, and trypsin has a glutamine. The analysis also suggests that this constrained arginine mimic, when present in an inhibitor, might enhance selectivity against other trypsin-like enzymes that have a glutamine at residue position 192.

The "beta-fluorine effect" in the non-metal hydride radical deoxygenation of fluorine-containing nucleoside xanthates

An alternative method to conduct a Barton-McCombie deoxygenation in nucleosides is described. The utility of the procedure is limited to structures with an electronegative substituent, particularly fluorine, in the beta-position relative to the radical center. The process is radical in nature and triggered by peroxides. The abstraction of hydrogen from the solvent is favorably influenced by the presence of a beta-fluorine.

Abdominal muscle paralysis in herpes zoster

Herpes zoster or Shingles, an inflammatory viral disease caused by varicella has classical clinical presentation with herpetic morphological pattern exhibited along one or more dermatomes. The self limiting skin disease is accompanied by pain and burning sensations leading to post herpetic neuralgia. The sensory component of the disease is so prominent that the motor involvement is often overlooked. It was not known till recently that profound muscle weakness can be a part of this syndrome. We report 2 cases of herpes zoster who had prominent appreciable motor weakness of the abdominal muscles following the disease. The weakness however has a better prognosis and the lesions in both of our patients healed in 6 months without leaving any residual paralysis.

Casein kinase II activity is required for transferrin receptor endocytosis

The effect of protein kinase inhibitors on transferrin receptor (TR) internalization was examined in HeLa, A431, 3T3-L1 cells, and primary chicken embryo fibroblasts. We show that TR endocytosis is not affected by tyrosine kinase or protein kinase C inhibitors, but is inhibited by one serine/threonine kinase inhibitor, H-89. Inhibition occurred within 15 min, was completely reversible after H-89 withdrawal, and was specific for endocytosis rather than pinocytosis since a TR mutant lacking an internalization signal was not affected. Interestingly, H-89 also inhibited the internalization of a TR chimera containing the major histocompatibility complex class II invariant chain cytoplasmic tail, indicating that the effect was not specific for the TR. Since H-89 inhibits a number of kinases, we employed a permeabilized cell endocytosis assay to further characterize the kinase. In permeabilized 3T3-L1 cells, addition of pseudosubstrate inhibitor peptides of casein kinase II (CKII) blocked TR internalization by more than 50%, whereas pseudosubstrates of cyclic AMP-dependent kinase A, protein kinase C, and casein kinase I had no effect. Furthermore, addition of purified CKII to the cell-free reactions containing CKII pseudosubstrates reversed the endocytosis block, suggesting that CKII or a CKII-like activity is required for constitutive endocytosis.

Decortication for empyema thoracis

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The design of potent and selective inhibitors of thrombin utilizing a piperazinedione template: part 1

Utilizing X-ray crystallography and molecular modeling, highly potent and selective peptidomimetic thrombin inhibitors have been designed containing a rigid piperazinedione template. The synthesis and biological activity of these compounds will be described.

The design of potent and selective inhibitors of thrombin utilizing a piperazinedione template: part 2

Potent and selective thrombin inhibitors have been prepared with a piperazinedione template and L-amino acids. Likewise, incorporation of D-amino acids led to potent inhibitors with a novel mode of binding. Herein, the structure activity relationships and structural aspects of these compounds will be described.

Cardiac hypertrophy: signal transduction, transcriptional adaptation, and altered growth control

Cardiac hypertrophy results from the enlargement of cardiac muscle and fibroblast cells. This abnormal pattern of growth can be elicited by a number of hypertrophic agents, such as cytokines and hormones that participate in normal cell-cell signaling events during development. Under conditions yet to be defined, these same signaling molecules can cause hypertrophy of the heart. Intracellular signal transduction pathways appear to be the prime means by which the hypertrophic signal is transduced in cardiomyocytes. There is no evidence that the signal transduction pathways in hypertrophic cardiomyocytes differ from those of normal cardiomyocytes. Perhaps the signal itself is aberrant, mistimed, misplaced, or occurring at non-physiological concentrations. Alternatively, as a quiescent cell, the cardiomyocyte may not be able to respond completely to a growth signal by turning on its proliferative machinery. Three avenues of research are described: (1) the study of the upregulation of the cardiac MLC-2 gene, (2) STAT proteins and activation of angiotensin II, and (3) hypertrophy as a perturbation of cell cycle controls.

Signal transduction and transcriptional adaptation in embryonic heart development and during myocardial hypertrophy

In comparing the pathological state of cardiac hypertrophy with early embryonic growth and development of the primitive heart, important and informative aspects of mechanisms that underlie activation of the gene expression pattern become apparent. Interestingly, in both cases the muscle phenotypes share the expression of a 'fetal' gene expression program, raising the question whether the same genetic mechanism is being called upon by signals associated with the onsets of cardiogenesis and myocardial hypertrophy. A cell specific transcription factor, CLP-1, was recently identified in our laboratory that is likely to play a crucial role, in conjunction with other known regulatory factors, in early cardiac events leading to cardiogenic cell specification and differentiation. We have also identified a novel mechanism that involves activation of the Jak/Stat signaling pathway that is linked to the autocrine angiotensin-II loop associated with the hypertrophic response in cardiomyocytes. Since early cardiac cell development and the hypertrophic state involve the expression of the same battery of genes, one may speculate that common transcription factors may account for assembling a competent apparatus responsible for transcribing the genes. Our present studies are designed to investigate the potential role of these factors in control of both processes.

cycloSal-Pronucleotides of 2'-fluoro-ara- and 2'-fluoro-ribo-2',3'- dideoxyadenosine as a strategy to bypass a metabolic blockade

Novel, lipophilic cycloSal triesters 4a-c and 5a-c were synthesized, respectively, from the ara- and ribo-configurated 2'-fluorinated-2', 3'-dideoxyadenosines 2 and 3. The cycloSal phosphotriesters were used as tools to study the effects of the two different sugar pucker conformations induced by two opposite configurations of the fluorine substituent at C2' of the dideoxyribose moiety. F-ara-ddA (2) is known to be an active anti-HIV agent, whereas the ribo-analogue 3 is inactive. Hydrolysis studies with the triester precursors 4a-c and 5a-c showed selective formation of the monophosphates of 2 and 3. The lipophilicity of the triester prodrugs was considerably increased by the cycloSal mask with respect to ddA (1), F-ara-ddA (2), and F-ribo-ddA (3). Phosphotriesters 4 and 5 proved to be completely resistant to ADA and AMPDA deamination. In parallel experiments, ribo-nucleoside 3 showed a 50-fold faster deamination rate relative to the ara-analogue 2. Against HIV in CEM cells, the phosphotriesters 4 proved to be 10-fold more potent than the parent nucleoside 2. Furthermore, the prodrugs 4 were active against MSV-induced transformation of C3H/3T3 fibroblasts, while 2 was inactive. More interestingly, the ribo-configurated phosphotriesters 5, prepared from the inactive F-ribo-ddA (3), showed a level of anti-HIV activity that was even higher than that of F-ara-ddA (2). Our findings clearly prove that the application of the cycloSal-pronucleotide concept to F-ribo-ddA (3) overcomes a metabolic blockade in the formation of the corresponding monophosphate.

Synthesis and structure-activity relationship of potent bicyclic lactam thrombin inhibitors

A simple and versatile method for preparation of (D)-Phe-Pro peptidomimetic bicyclic thiazolidine lactams is presented. These bicyclic lactams have chemical diversity alpha to the lactam carbonyl and, when linked to electrophilic arginines, provide potent thrombin inhibitors.

Identification of a novel cardiac lineage-associated protein(cCLP-1): A candidate regulator of cardiogenesis

We describe the isolation and characterization of a cDNA clone, called cCLP-1, that is a candidate for the previously described early cardiac-specific transcription factor BBF-1. BBF-1 binds the MEF2 (or element B) binding site within the cardiac myosin light chain 2 (MLC2) gene promoter. We used the element B sequence as a probe to screen an expression library constructed from mRNA obtained from the presumptive heart-forming regions of stage 6 chicken embryos. This yielded the cCLP-1 cDNA clone. Gel-shift analysis of stage 6 embryonic chicken protein extracts suggests that a protein that is recognized by the anti-cCLP-1 antibody binds to the same element B binding site to which BBF-1 binds. cCLP-1 mRNA was detected early in chicken development, prior to cardiac fate assignment at stage 4. The expression pattern of cCLP-1, based on whole mount in situ hybridization, coincides remarkably well with the established morphogenetic field of early heart formation. The nuclear localization of cCLP-1 is phosphorylation-dependent, suggesting that cCLP-1 may be a member of that class of transcription factors whose activity is regulated by cytoplasm to nucleus transport. Taken together, these data suggest that cCLP-1 may encode a novel transcription factor whose expression pattern is in agreement with that of the cardiogenic precursor cells of the early chicken embryo.

Conformationally restricted nucleosides. The reaction of adenosine deaminase with substrates built on a bicyclo[3.1.0]hexane template

Adenosine deaminase (ADA) can discriminate between two distinct (North and South), conformationally rigid substrate conformers. (N)-methanocarba-2'dA (4) is deaminated 100 times faster than the antipodal (S)-methanocarba-2'dA (5), whereas a non-rigid analogue, aristeromycin (6), is deaminated at an intermediate rate. These results are in agreement with crystallographic data from ADA-ribonucleoside complexes showing the furanose ring of the bound purine in a C3'-endo (North) conformation. The data presented here suggests that 4 and 5 are useful probes to ascertain conformational preferences by purine metabolizing enzymes.

Potent and selective bicyclic lactam inhibitors of thrombin: Part 3: P1' modifications

The synthesis and antithrombotic activity of a series of nonpeptide bicyclic thrombin inhibitors are described. We have explored the SAR around the P1' site. Modification of the P1' site has been found to affect potency and selectivity.

Potent and selective bicyclic lactam inhibitors of thrombin: Part 2: P1 modifications

The synthesis and antithrombotic activity of a series of nonpeptide bicyclic thrombin inhibitors is described. We have explored the SAR with modifications to the P1 site. The introduction of arginine mimetics at the P1 site led to potent and selective thrombin inhibitors.

Potent bicyclic lactam inhibitors of thrombin: Part I: P3 modifications

Peptidomimetic inhibitors of general structure 1 have been prepared. Optimization of the binding affinities of these compounds through variation of the P3 hydrophobic residue is described. Selected substituted bicylic lactams displayed interesting pharmacological profiles both in vitro and in vivo.