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M A Islam

Publications and source records attributed to M A Islam.

At least 37 records · Page 2Linked to original sources
PubMed1998

[The involvement of muscarinic M1 receptor in the regulation of action potentials in mouse isolated right atria].

We investigated the involvement of muscarinic M1 receptors in the regulation of action potentials, and its modulation by adrenergic signaling and its change by aging in mouse isolated right atria using a conventional glass microelectrode technique. In adult mice, acetylcholine (ACh) (3-10 microM) reduced the maximum upstroke velocity of action potential (Vmax) followed by an increase. In electrically driven atria, similar effects of ACh on Vmax were observed. McN-A-343 (100-300 microM), a M1 agonist, reduced Vmax, while M2 agonist oxotremorine (0.1-0.3 microM), increased it. Isoproterenol (3 nM), antagonized ACh- and McN-A-343-induced reduction of Vmax, and potentiated the ACh- and oxotremorine-induced increase. The effects of isoproterenol were mimicked by cholera toxin, a Gs-protein activator, and forskolin, a direct activator of adenylyl cyclase. H-89, a selective protein kinase-A inhibitor, abolished the antagonism by isoproterenol of ACh-induced reduction in Vmax. Calphostin C, a selective protein kinase-C inhibitor, but not pertussis toxin attenuated ACh-induced reduction in Vmax. These results show that 1) ACh-induced reduction of Vmax and its subsequent increase are mediated by the activation of muscarinic M1 and M2 receptors, respectively, 2) the M1 and M2 subtypes may exert a balancing action on each other, and 3) the beta-adrenergic activation antagonizes M1-mediated effects, and enhances M2-mediated effects, on Vmax. In young mice, ACh (5-10 microM) increased Vmax, which was abolished by AF-DX 116 (0.3 microM), a M2 antagonist. In aged mice, ACh did not affect Vmax up to a concentration of 10 microM. The present findings may be of importance in the occurrence of cardiac disfunction in aging.

(4-(m-Chlorophenylcarbamoyloxy)-2-butynyl)trimethy↗
PubMed1998

Acetylcholine-induced biphasic effect on the maximum upstroke velocity of action potential in mouse right atria: interaction with beta-adrenergic signaling cascade.

Several lines of evidence suggest the molecular and functional entity of muscarinic M1 receptors in mammalian heart. We have reported that acetylcholine (ACh) reduces the maximum upstroke velocity of action potential (Vmax) through activation of muscarinic M1 receptors, which is followed by a muscarinic M2 receptor-mediated increase. The present study sought to determine whether activation of beta-adrenergic receptors modulates the muscarinic M1 and M2 receptor-mediated effects on Vmax in isolated mouse right atria. Intracellular recordings of spontaneous action potential were done using the conventional glass microelectrode technique. Isoproterenol (3 nM) completely antagonized ACh (5 microM)-induced reduction in Vmax. The antagonism was accompanied by a subsequent increase in Vmax. Propranolol (0.3 microM) abolished the effects of isoproterenol on ACh-induced changes in Vmax. Isoproterenol antagonized McN-A-343 (4-(m-chlorophenyl-carbamoyloxy)-2-butynyltrimethylammonium chloride) (300 microM, a muscarinic M1 receptor agonist)-induced reduction in Vmax. Oxotremorine (0.03 microM), a muscarinic M2 receptor agonist, did not affect Vmax by itself, but significantly increased it in the presence of 3 nM isoproterenol. The effects of isoproterenol were mimicked by cholera toxin (100 nM, 1 hr), a Gs-protein activator, and forskolin (10 nM), a direct activator of adenylyl cyclase. H-89 (N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulphonamide++ +, 1 microM), a selective protein kinase (PK)-A inhibitor, abolished the antagonism by isoproterenol of ACh-induced reduction in Vmax. The present results suggest that activation of the beta-adrenergic-Gs-adenylyl cyclase system antagonizes ACh-induced reduction (muscarinic M1-mediated) and potentiates the subsequent increase (muscarinic M2 receptor-mediated) in Vmax. The beta-adrenergic antagonism of ACh-induced reduction in Vmax may involve cross-talk between PK-A and PK-C signaling pathways.

(4-(m-Chlorophenylcarbamoyloxy)-2-butynyl)trimethy↗
PubMed1997

Effect of early vitamin A supplementation on cell-mediated immunity in infants younger than 6 mo.

One hundred twenty infants were randomly assigned to receive either 15 mg vitamin A or placebo with each of three DPT/OPV (diphtheria, pertussis, tetanus/oral polio vaccine) immunizations at monthly intervals. Sixty-two received vitamin A and 58 received placebo. One month after the third supplementation dose, the response to the delayed cutaneous hypersensitivity test [multitest cell-mediated immunity (CMI) skin evaluation] for tetanus, diphtheria, and tuberculin (purified protein derivative, PPD) was the same in the vitamin A and placebo infants. The number of anergic infants was 17 (27%) and 19 (33%) in the vitamin A and placebo groups, respectively. The number of positive tests among well-nourished infants was significantly higher than that in malnourished infants irrespective of supplementation (P < 0.001). Among the infants with adequate serum retinol concentrations (> 0.7 mumol/L) after supplementation, the vitamin A-supplemented infants had a significantly higher proportion of positive CMI tests than the placebo infants (chi-square test: 8.99, P = 0.008). Among the infants with low serum retinol concentrations (< 0.7 mumol/L) after supplementation, vitamin A supplementation had no effect on CMI response. These results indicate that CMI in young infants was positively affected by vitamin A supplementation only in those infants whose vitamin A status was adequate (ie, serum retinol > 0.7 mumol/L) at the time of the CMI test. CMI was consistently better in well-nourished infants irrespective of supplementation.

Aging↗
PubMed1997

Zinc status of breastfed and formula-fed infants of different gestational ages.

Zinc status in 186 full term and preterm infants was determined at birth, and 3, 6, 9, and 12 months of age along with determination of zinc levels in breast or formula milk to find out if routine zinc supplements are needed during infancy. The leukocyte and plasma zinc levels in all breastfed infants were high at birth and gradually declined reaching lowest values by 4-6 months of age, and improved to normal levels by 9 months following weaning. The preterm infants however, had significantly (P < 0.05) higher leukocyte zinc (213.6 +/- 46.91 micrograms/10(10) cells) at birth compared to term infants. Colostrum of all the mothers had higher zinc concentrations which declined to significantly lower levels in breastmilk by 4-6 months of lactation, corresponding to the age when the breastfed infants had lower zinc levels. The improvement of the levels to normal after weaning suggests that the fall in zinc status during early infancy could be a transient phenomenon which could be reversed by proper weaning, thus strengthening the plea for timely food supplements rather than the need for single nutrient supplements. Formula-fed full term infants had significantly lower leukocyte zinc levels (49.3 +/- 2.59 micrograms/10(10) cells) at 3 months of age compared to breastfed infants of the same age (92.8 +/- 14.04 micrograms/10(10) cells). Even these infants improved their zinc status after weaning on par with breastfed infants. The functional significance of their transient, but low zinc values during early infancy needs to be investigated.

Analysis of Variance↗
PubMed1996

Acute respiratory infections prevent improvement of vitamin A status in young infants supplemented with vitamin A.

At immunization contact, 165 infants 2.5 mo old were randomly assigned to receive either 15 mg vitamin A (retinyl palmitate) or placebo. Three doses were given at monthly intervals with each diphtheria, pertussis, tetanus and oral polio (DPT/OPV) immunization dose. The diarrhea and acute respiratory infection (ARI) morbidity was similar in the vitamin A and placebo groups. However, the duration (days per child-year, mean +/- SD) of ARI was less in the vitamin A group compared with placebo group (27.6 +/- 17.1 vs. 40.8 +/- 22.7; P = 0.005). Fasting retinol concentrations were measured at entry and in 61 infants, the relative dose response (RDR) test was done 1 mo after the third dose of vitamin A. Eighty-five percent of the infants had serum retinol concentration < 0.70 mol/L at entry. After 3 mo the serum retinol levels improved significantly in both groups, and in the vitamin A-supplemented group the serum retinol concentration was significantly better than that in the placebo group (P= 0.02). However, 61% of the infants remained deficient despite vitamin A supplementation. Among vitamin A-supplemented infants only, diarrhea and ARI morbidity during the 3-mo period were compared in children with normal versus children with abnormal RDR at the end of the supplementation period. The ARI episodes were more frequent in the supplemented infants who remained vitamin A deficient at the end of the 3 mo (P = 0.027). Also, the cumulative duration (days, mean +/- SD) of fever and cough was 5.0 +/- 2.8 in the normal versus 11.2 +/- 6.0 in the deficient group (P = 0.04). The results of this study suggest that a large proportion of infants remain vitamin A deficient even after large dose vitamin A supplementation because of frequent respiratory infections, particularly those accompanied by fever.

Acute Disease↗
PubMed1996

Death in a diarrhoeal cohort of infants and young children soon after discharge from hospital: risk factors and causes by verbal autopsy.

Assessing mortality pattern of children after discharge from hospital is important to guide appropriate management policy. We studied young children aged 1-23 months, who were discharged from an urban Diarrhoea Treatment Hospital. Children were enrolled on discharge from the hospital, and followed at home after 6 and 12 weeks to assess post-discharge mortality. Of 500 children, 427 were available for evaluation at home 6 weeks after discharge. The median age of the children was eight months, 77 per cent of whom were less than 12 months of age. Of the 427 children, 30 (7 per cent) died within 6 weeks and two died within 12 weeks of discharge from hospital. The median survival time of the deceased was 11 days. Children less than 6 months of age had a five times greater risk of death compared with those aged 6 months or older. Malnutrition, non-breastfeeding, and lack of immunization were important risk factors for death. As ascertained by verbal autopsy, the underlying causes of death were respiratory diseases and watery diarrhoea. Malnutrition and low birth weight were the main associated causes. Hospitalized children, especially young infants, should be given special attention and need to be followed preferably within a week of discharge.

Bangladesh↗
PubMed1996

Potentiation by higenamine of the aconitine-induced positive chronotropic effect in isolated right atria of mice: the effects of cholera toxin, forskolin and pertussis toxin.

Aconitine and higenamine are the major cardioactive compounds obtained from processed aconite. The chronotropic interaction between these two compounds was investigated in isolated right atria of mice. Both aconitine and higenamine potentiated the action of the other. Practolol (1 nM), a selective beta 1-adrenergic antagonist, but not butoxamine (1 microM), a beta 2-adrenergic antagonist, blocked the potentiation by higenamine (5 nM) of the aconitine-induced positive chronotropic effect and, at high concentrations (30 and 300 nM) also shifted the aconitine concentration-response curves to the right. The potentiating interaction between aconitine and higenamine was reversed by pretreating with cholera toxin (CTX) and forskolin. In CTX (100 nM, 1 h)- and forskolin (30 and 100 nM)-treated atria, higenamine significantly depressed the aconitine-induced response, which was abolished by pertussis toxin (PTX, 150 micrograms/kg, i.p., 3 d). Neither CTX (50 and 100 nM) nor forskolin (15-100 nM) significantly affected the aconitine-induced positive chronotropic effect, while PTX (150 micrograms/kg) depressed it. These results suggest that the potentiating interaction between aconitine and higenamine involves "cross-talk" between the beta 1-adrenergic signalling pathway and Gi-protein.

Aconitine↗
PubMed1995

Mothers' knowledge about vaccine preventable diseases and immunization coverage in a population with high rate of illiteracy.

In a case-control analysis of cross-sectional data, 328 children aged 12-35 months and their mothers were studied to identify the factors associated with delayed or non-immunization of their children. Delayed or non-immunization was associated with low socio-economic status, maternal illiteracy, and lack of mothers' knowledge on vaccine preventable diseases as recommended by the Expanded Programme on Immunization (EPI). The association of this lack of mother's knowledge with no or delayed immunisation persisted after adjusting the effects of others in logistic regression analysis (Odds Ratio 16.7; 95 per cent confidence interval: 15.65-17.8; P < 0.0001). The results indicate that even in the presence of maternal illiteracy, educating mothers about the vaccines and vaccine preventable diseases may be highly effective in increasing the immunization coverage.

Bangladesh↗
PubMed1995

Cholera toxin accentuates the antagonism by acetylcholine of higenamine-induced positive chronotropy is isolated right atria of mice.

+/- -Higenamine (demethylcoclaurine), a cardiotonic principle from aconite root, chronotropic and inotropic actions mediated through beta 1-adrenergic receptors. We have investigated the influence of cholera toxin (CTX), a Gs-protein activator, and pertussis toxin (PTX), a Gi-protein inhibitor on the chronotropic interaction between higenamine and a muscarinic agonist, acetylcholine (ACh) in the isolated right atria of mice. CTX (100nm, 1h) pretreatment accentuated the inhibitory responses to cumulative applications of ACh (30nM--30 microns for the positive chronotropic effects induced by higenamine (100nM), isoproterenol (3 and 10 nM) or dobutamine (100nM). In normal atria (CTX-untreated), ACh physiologically antagonized the positive chronotropic effects of these beta-adrenergic agonists. Pretreatment with PTX (150 microgram/kg, i.p., 3d) abolished the CTX (100nm, 1 h)-induced accentuation in the inhibitory effect of ACh against higenamine. PTX pretreatment also attenuated the physiological antagonism by ACh against higenamine in normal atria. The negative chronotropic effect of ACh was not affected by a submaximal concentration of forskolin (1 micron). The These results suggest an accentuated antagonism between higenamine and ACH in CTX-treated, but not in untreated, isolated right atria of mice, which may occur through a functional interaction between the beta1-adrenergic-Gs and muscarinic-Gi systems.

Acetylcholine↗
PubMed1995

Brain lesions in chickens experimentally infected with a neuroadapted strain of mesogenic Newcastle disease virus.

Neuroadapted Newcastle disease virus (Q10) was selected by tenth serial passage, in the chicken brain of a mesogenic strain (Q0) originally isolated from quails. Specific pathogen-free birds were inoculated intranasally with one of these viruses. At daily intervals for 7 days and then at 10, 14, and 21 days post-inoculation (PI), two birds from each group were killed and samples of the brain were collected for histopathological and virological examination. Q10 caused severe nonsuppurative encephalitis with nervous signs and high mortality. Lesions characterized by neuronal degeneration and necrosis, perivascular lymphocytic infiltration, and focal or diffuse astrogliosis occurred mainly in the parahippocampal cortex, hippocampus, hyperstriatum, neostriatum, subleptomeningeal and periventricular regions of the cerebrum. Spongy changes with neuronal degeneration and axonal spheroids were also observed in the brain stem of a few cases. The amount of virus in the brain reached a peak on day 4 PI and virus could not be recovered from the brain after 6 days PI. In contrast, Q0 caused nonfatal asymptomatic disease and virus could not be isolated from the brain, sections of which showed only minimal inflammatory changes. This difference in the lesions of the brain might be related to neurovirulence and, neuroadaptation by serial passage may occur by increased efficiency of viral replication in neurons.

Animals↗
PubMed1995

Administration of 25,000 IU vitamin A doses at routine immunisation in young infants.

OBJECTIVE: To investigate whether monthly administration of vitamin A at routine immunisation produces any side-effects, and to examine the effect of this supplementation on the vitamin A nutrition status of infants. DESIGN: A double-blind randomised placebo-controlled clinical trial. SETTING: Immunisation clinic of a large diarrhoea treatment centre. SUBJECTS: Infants aged 6-17 weeks who will receive their first diphtheria-pertussis-tetanus/oral polio vaccine (DPT/OPV) dose. METHODS: Infants were randomly assigned to receive either 25,000 IU vitamin A or placebo. Three such doses were given with each immunisation dose at monthly intervals. Infants were examined by a physician before and during 24 h after the doses and any signs of toxicity were recorded. Venous blood was drawn at entry and 1 month after the 3rd dose for retinol assay. RESULTS: One hundred and one infants received vitamin A and 98 received placebo. Decreased feeding, irritability, diarrhoea, and vomiting were comparable between the two groups. In the vitamin A group five infants developed bulging fontanelle; three of them developed it once (after 1st, 2nd and 3rd dose respectively), one developed it twice (after both the 2nd and 3rd dose), and the other infant after all three doses. In the placebo group a single child developed bulging fontanelle after the 3rd dose. In all the cases the bulging disappeared within 48 h of onset except in one infant, in whom it subsided at 60 h. The total bulging episodes in the vitamin A and placebo groups were 8 and 1 respectively (RR = 7.7; P < 0.04). However, none of these infants had irritability. At entry fasting retinol level was < 10 micrograms/dl in 35% infants and in 87% infants it was < 20 micrograms/dl. After the third dose fasting retinol level was marginally better in the vitamin A group (mean +/- s.d.: 21.9 +/- 8.2 vs 19.2 +/- 7.8; P = 0.05). However, 47% infants receiving supplementation still had serum retinol level <20 micrograms/dl. CONCLUSION: The results suggest that administration of 25,000 IU of vitamin A in young infants along with routine immunisations, though associated with increased incidence of transient bulging fontanelle without any associated adverse signs or symptoms, may still be inadequate to prevent deficiency in this population. SPONSORSHIP: This study was funded by the United States Agency for International Development (USAID) under grant no. DPE-5986-A-1009-00 with the International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B). The ICDDR,B is supported by countries and agencies which share its concern for the health problems of developing countries.

Double-Blind Method↗
PubMed1995

Branchial cleft anomalies--a study of 20 cases.

Preauricular sinus, branchial cyst, branchial sinus and branchial fistula are the result of incomplete obliteration of branchial clefts. Classically these lesions have particular sites and nature. The aim of this three years retrospective study was to see the prevalence of these conditions as well as the outcome of the conventional surgery. Twenty cases of branchial cleft anomalies were reported, of which 60% had with preauricular sinus. One case with preauricular sinus had recurrence during postoperative follow-up.

Adolescent↗
PubMed1994

Evaluation of bioassay for toxicity of ciguateric fish and associated toxins.

Evaluation of the mouse toxicity assay symptom of hind leg paralysis (HLP) with mouse death by statistical analysis is presented in this study. The fishes assessed were herbivores including Ctenochaetus strigosus (kole), Ctenochaetus hawaiiensis, Acanthurus sandvicensis (manini), and Mugil cephalus (mullet); and the carnivores, Cephalopholis argus (roi) and Cheilinus rhodochrous (po'ou). The latter can also be considered an omnivore. The extracts of both herbivore and carnivore species appeared to be most toxic when HLP occurred in the mice. Ninety-three percent of the mice with HLP died, whereas when no HLP (NHLP) occurred, only 51% of the mice died. Carnivore flesh extracts (po'ou and roi) were least toxic with one death out of a total 22 mice. The unidentified toxin associated with HLP appears to differ in biological properties from that of ciguatoxin(s) in that it was not found in the flesh tissues of carnivores. Further chemical studies of this toxin(s) is being addressed presently.

Animals↗
PubMed1994

Factors associated with safe preparation and home use of sugar-salt solution.

The use of oral rehydration salts is frustratingly low, mostly because one must visit a health care provider to procure the packets. Mothers are advised to use sugar-salt solution (SSS) and other home-based fluids as first fluid replacement during diarrhoea. However, the use rate of SSS is also not encouraging and few mothers can prepare it correctly. We conducted an observation study on mothers who reported to the diarrhoea treatment centre of the International Centre for Diarrhoeal Disease Research, Bangladesh during September 1990 through to December 1992. At quarterly intervals, 240 mothers were recruited randomly to elicit their knowledge and ability to prepare SSS. Most (94.6%) of the mothers knew about the solution, but only 62% of them used the solution at home. The use rate was higher when mothers came to know about the solution through interpersonal communication (e.g. community health workers, doctors, friends, neighbours and relatives) and from multiple sources (72%) than when they learned about it from the media or from a single source (54%). As many as 85.4% of the mothers could prepare the solution within the safe limits of sodium concentrations (30 to 100 mmol/l). The figure rose to 95.8% after practical instruction as to how to prepare the solution. This improvement was dependent neither on the literacy level of mothers nor on their knowledge and use of the solution earlier. To increase interpersonal communication and to improve mothers' behaviour in using and correctly preparing SSS, every contact with health care providers should be utilised for organising sessions on the use and preparation of the solution.

Bangladesh↗
PubMed1994

Impact of health education on the feeding of green leafy vegetables at home to children of the urban poor mothers of Bangladesh.

To evaluate the impact of health education on mothers, on the feeding of their children green leafy vegetables (GLV) at home, we studied 160 children aged 6 to 35 months and their mothers in two intervention groups and one comparison group. The mothers of the first intervention group (n = 44) were given health education including a feeding demonstration, by offering a single meal of cooked GLV to their children. The mothers in the second intervention group (n = 36) received health education only. Mothers of both the intervention groups were visited at home after eight weeks of intervention without prior notice, and for each of them an immediate neighbourhood mother having a child in the same age range was selected as a comparison mother (n = 80). During this visit, mothers were asked whether they had cooked GLV that day and fed these to their children; this was confirmed by spot-checking. Also, mothers were interviewed to elicit their perceptions about GLV. The percentages of mothers who thought that GLV are good for health were 88.7%, 86.1% and 76.2% in groups 1, 2 and comparison respectively (P = 0.06). However, the percentages of mothers who actually fed their children GLV were 57%, 64% and 26% in groups 1, 2 and comparison group respectively (P < 0.001). The influence of health education on GLV feeding persisted after controlling for the effect of maternal literacy (Mantel Haenszel chi-square = 16.99; P < 0.0001) and family income (Mantel Haenszel chi-square = 17.36; P < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Bangladesh↗
PubMed1994

Diabetes mellitus-induced enhancement of prostaglandin F2 alpha-responses is inhibited by lipoxygenase- but not cyclooxygenase-inhibitors in mesenteric veins and arteries of mouse and rat.

The mechanisms responsible for diabetes mellitus-induced enhancement of prostaglandin (PG) F2 alpha response were investigated in vascular smooth muscles isolated from diabetic mice and rats. Streptozocin (150 mg/kg, i.v. bolus, 6 week-elapsed)-ddY mice and (60 mg/kg, i.v. bolus)-Wistar rats and genetically diabetic GK-rats were used. The responses to PGF2 alpha were enhanced in small blood vessels such as mesenteric arteries (diabetic rats) and veins (diabetic mice) and they were reduced in large blood vessels such as the aorta and vena cava (diabetic rats). The enhanced response to PGF2 alpha in diabetic blood vessels was significantly inhibited by nordihydroguaiaretic acid (NDGA) (0.03 mM) and phenidone (0.05 mM), lipoxygenase inhibitors, cycloheximide (1 mg/kg, i.v.), a protein synthesis inhibitor and actinomycin D (2.8 mg/kg, i.v.), a RNA polymerase inhibitor, but neither inhibited by cyclooxygenase inhibitors, a thromboxane antagonist, nor Ca2+ antagonists. The PGF2 alpha response was also enhanced with aging alone, whereas the extent of enhancement was less than that with diabetes mellitus, and not significantly blocked by NDGA. These results demonstrate that diabetes mellitus-induced imbalance in the regulation of the eicosanoid metabolic pathways (suppressed cyclooxygenase and accelerated lipoxygenase) may cause the enhancement of PGF2 alpha-induced responses in small blood vessels.

Aging↗
PubMed1994

Positive chronotropic and inotropic effects of higenamine and its enhancing action on the aconitine-induced tachyarrhythmia in isolated murine atria.

Aconitine and higenamine are the components of aconite root. We investigated the cardiac effects of these compounds on murine right and left atria and the interaction of higenamine with aconitine on the rate of spontaneously beating right atria. Higenamine increased the rate (EC50 = 38 nM) and the force of contraction (EC50 = 97 nM), the maximal responses being comparable with those of isoproterenol. The positive chronotropic effect of higenamine was antagonized by propranolol (30-300 nM) and practolol (10 nM-3 microM), but not by butoxamine (1 microM), indicating that it was a beta 1-adrenoceptor-mediated action. The positive chronotropic effect of higenamine was not changed by pretreatment with reserpine (4 mg/kg, i.p., 4 hr). Aconitine (0.16-0.25 microM) induced tachyarrhythmia in right atria was attenuated by quinidine (1 microM), atropine (8.6 microM) and AF-DX 116 (8.6 microM), suggesting that aconitine activates sodium channels and muscarinic receptors. Higenamine (2.5 nM) and dobutamine (1 nM) did not cause chronotropic effects by themselves, but enhanced the aconitine-induced tachyarrhythmia. These results indicate that higenamine is a beta 1-adrenoceptor full agonist in murine atria and that the aconitine-induced tachyarrhythmia is augmented by the beta 1-adrenergic action of higenamine.

Aconitine↗