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M A Nayeem

Publications and source records attributed to M A Nayeem.

At least 19 recordsLinked to original sources
PubMed1999

Induction of 72-kDa heat shock protein does not produce second window of ischemic preconditioning in rat heart.

Ischemic preconditioning (PC) induces delayed phase of protection, known as the second window of protection (SWOP). We investigated this phenomenon in rat and correlated it with the expression of 72-kDa heat shock protein (HSP 72). Rats were preconditioned with 1, 2, and 3 cycles of 5-min left anterior descending artery occlusions, each separated by a 10-min reperfusion (PC x 1, PC x 2 and PC x 3, respectively). Another group of rats was preconditioned with heat shock (HS) by raising temperature to 42 degreesC for 15 min. Twenty-four hours later, rats were given sustained ischemia for 30 min and 90 min of reperfusion. Infarct sizes (%risk area) were 40.0 +/- 7.5, 37.6 +/- 5.6, and 47.6 +/- 2.4 (mean +/- SE) for PC x 1, PC x 2, and PC x 3 hearts, respectively, which were not different from the sham (49.9 +/- 3.9, P > 0.05). In contrast, infarct size was reduced from 47.5 +/- 3.8% in sham to 4.7 +/- 2.3% (P < 0.01) 24 h after HS. Additionally, early PC significantly reduced infarct size from 47.5 +/- 3.8% in controls to 6.0 +/- 1.2 and 5.0 +/- 1.1% with PC x 1 and PC x 3. Repeated PC cycles induced over a threefold increase in HSP 70 mRNA after 2 h compared with sham (P < 0.05). HSP 72, which increased 24 h after PC or HS, was not significantly different between the two PC stimuli. We conclude that PC does not induce SWOP in rat heart despite enhanced expression of HSP 72. In contrast, HS-induced delayed protection was associated with enhanced accumulation of HSP 72. It is possible that SWOP and HS have distinct mechanisms of protection that may not be exclusively related to HSP 72 expression.

Animals↗
PubMed1998

Whole body heat shock fails to protect mouse heart against ischemia/reperfusion injury: role of 72 kDa heat shock protein and antioxidant enzymes.

The transgenic mice overexpressing heat shock protein 72 (HSP72) or antioxidants have been reported to be more resistant to myocardial ischemia/reperfusion injury. However, it remains unknown whether whole body heat stress (HS) which may induce HSP72 or endogenous antioxidants affords similar protection in the mouse heart. Adult male mice were treated with either HS (42 degrees C for 15 min) or anesthesia only (SC) against a group of non-stressed controls (NC). At 6 or 24 h later, the hearts were excised and perfused at a constant pressure of 55 mmHg in Langendorff mode. Following 30 min equilibration, hearts were subjected to 20 min of global ischemia and 30 min reperfusion (37 degrees C). Ventricular force was measured by a force-displacement transducer attached to the apex. Leakage of intracellular enzymes (CK, LDH) was measured in coronary efflux. Infarct size was determined by tetrazolium staining. The results showed that no significant differences between HS, SC, and NC groups in ventricular contractile function, CK and LDH release, or infarct size were observed at either time window. HS enhanced the expression of HSP72 in mouse hearts by two- to three-fold, whereas antioxidant enzyme activities (catalase and MnSOD) did not change significantly. We conclude that HS does not precondition the isolated perfused mice hearts against ischemia/reperfusion injury, despite induction of HSP72.

Animals↗
PubMed1997

Monophosphoryl lipid A protects adult rat cardiac myocytes with induction of the 72-kD heat shock protein: a cellular model of pharmacologic preconditioning.

We examined the in vitro preconditioning effect of non-toxic derivative of endotoxin, monophosphoryl lipid A (MLA) in adult rat cardiac myocytes. Cultured 5-7-day-old myocytes were preconditioned for 4 h by treatment with 200 ng/ml MLA. Twenty h later, cells were subjected to simulated ischemia by incubation in 0.75 mm sodium hydrosulfite, 12 mM KCl, 20 mM dl-lactic acid and 10 mM 2-deoxy-D-glucose (pH 6.5) for 2 h. MLA caused a significant reduction in the levels of LDH from 286+/-8 units/l in controls to 165+/-5 units/l (mean+/-s.e.m.; P<0.0001). Similarly, CK significantly decreased from 104+/-3.1 in controls to 85+/-1.4 U/l (P<0.001). Western blot analysis indicated a significant accumulation of 72 kD heat shock protein in MLA treated as compared to control cells. No changes in 27, 32, and 90 kD heat shock proteins were discernible in the MLA treated group. These data suggest a significant "anti-ischemic" effect of MLA in myocytes that is accompanied by induction of 72 kD heat shock protein.

Animals↗
PubMed1997

Delayed preconditioning of cultured adult rat cardiac myocytes: role of 70- and 90-kDa heat stress proteins.

We investigated the protective effect of heat stress and metabolic preconditioning in cultured adult rat cardiac myocytes and correlated this effect with induction of heat shock proteins (HSP). Myocytes were preconditioned with sublethal heat shock or metabolic preconditioning for 30 min. Twenty hours later, preconditioned myocytes were subjected to lethal heat shock (46 degrees C for 2 h) or ischemia by incubation in ischemic buffer for 2 h. Cellular injury index was reduced from 69 +/- 4.0% in lethally heat-shocked cells to 27.0 +/- 1.6% with heat shock preconditioning (mean +/- SE; P < 0.01) and 19.0 +/- 3.0% with metabolic preconditioning (P < 0.01). Cellular injury index was 81.0 +/- 1.0% in ischemic myocytes and was reduced to 25.9 +/- 2.7 and 21.4 +/- 2.6% in heat shock- and metabolic-preconditioned myocytes, respectively (P < 0.01). A significant cross-tolerance of myocytes against lethal injury was observed with the two preconditioning methods. Western blot analysis revealed 3.3- and 2.5-fold increases in HSP 90 and 500- and 15-fold increases in HSP 70 with heat shock and metabolic preconditioning, respectively. HSP 27 expression remained unaltered relative to control cells. We conclude that heat shock and metabolic preconditioning induce delayed tolerance against lethal injuries in adult cardiac myocytes with elevated levels of HSP 70 and HSP 90.

Animals↗
PubMed1997

ATP-sensitive potassium channel mediates delayed ischemic protection by heat stress in rabbit heart.

Heat shock protects against myocardial ischemia-reperfusion injury possibly via increased expression of heat shock proteins. The direct evidence of heat shock protein protection in vivo remains circumstantial, and no other new mechanism of protection has been proposed. Recent studies suggest that opening of ATP-sensitive K+ channels (KATP channels) plays an important role in ischemic preconditioning; however, it is not known whether this channel is also important in delayed protection conferred by heat shock. Anesthetized rabbits underwent heat shock treatment by raising core temperature to 42 degrees C for 15 min. Twenty-four hours later, the animals were reanesthetized and subjected to regional ischemia-reperfusion. The specific KATP channel blockers glibenclamide (0.3 mg/kg i.p.) and sodium 5-hydroxydecanoate (5HD; 5 mg/kg i.v.) were used to block the channel function. The drugs were administered at two different times, either pre-heat stress or preischemia. Infarct size was determined by triphenyltetrazolium chloride staining. The 72-kDa heat shock protein (HSP 72) was measured by Western blots. Our results show that heat shock produced a marked reduction in infarct size (39.4 +/- 8.1 to 14.3 +/- 2.5% of risk area, P < 0.05). Glibenclamide and 5HD completely abolished heat shock-induced reduction in infarct size (42.3 +/- 0.32 and 33.7 +/- 4.8%) when given before ischemia-reperfusion; however, these antagonists failed to block protection when administered before the onset of heat shock. Furthermore, the enhanced expression of HSP 72 in heat shock groups was not diminished by glibenclamide or 5HD, suggesting a lack of a direct role of this protein in conferring cardiac protection by heat shock. The complete blockade of cardiac protection by glibenclamide and 5HD strongly suggests that opening of this channel is a very important component of heat shock-induced ischemic protection in rabbit hearts.

Animals↗
PubMed1994

Leucocyte migration inhibition index responses of patients of amoebic liver abscess to various antigens of Entamoeba histolytica.

The whole amoebic lysate (WAL), Sephadex G-200 eluted fraction-I. (F-I), detergent dissected membrane proteins (DDMP), amoebic membrane glycoprotein (AMG) and amoebal RNA were extracted from E. histolytica. Amoebal RNA recognized 98.21% where as F-I, AMG, DDMP and WAL recognised 92.85, 91.07, 89.28 and 75% of total 56 clinically proven and amoebic serology positive amoebic liver abscess cases respectively. Intensity of recognition of individual fraction i.e., leucocyte migration inhibition index of each fraction was found to be highly significant (P < 0.001) when compared to whole amoebic lysate. This indicate the leucocyte migration inhibition index responses of patients of amoebic liver abscess to various antigenic fractions of E. histolytica with variations.

Adult↗
PubMed1993

Correlation between membrane glycoprotein and detergent dissected membrane protein in the assessment of LMIF: a report of 51 ALA cases.

Assessment of 51 amoebic liver abscess cases for leukocyte migration inhibition factor released using membrane glycoprotein and detergent dissected membrane protein (DDMP) of axenic Entamoeba histolytica (NIH:200). Lymphokines release by T lymphocytes in response to purified amoebic membrane glycoprotein (PAMG) against whole amoebic lysate (WAL), dissect out protein against whole amoebic lysate and membrane glycoprotein against dissected protein was tested by leukocyte migration inhibition test on blood samples from proved amoebic liver abscess cases. A significant increase was noted in the release of lymphokines and 100% positivity was observed with both PAMG and DDMP compared to 78% with whole amoebic lysate. The difference between means leukocyte migration indices of the membrane glycoprotein and whole amoebic lysate, detergent dissected protein and whole amoebic lysate with regards to release LMIF were found to be highly significant (P < 0.001), (P < 0.005) respectively. But insignificant difference and very much similarity was noted between the means of membrane glycoprotein and dissect out protein sensitized T lymphocytes with regards to lymphokine release in vitro. This shows the patients had high degree of leukocyte sensitized to pure amoebic membrane glycoprotein and detergent dissected membrane protein compared to whole amoebic lysate. These findings indicate that detergent dissected protein has similar antigenicity with membrane glycoprotein in elicitation cell mediated immune response in amoebic liver abscess cases.

Animals↗
PubMed1993

Correlation between antiamoebic IgG and autoreactive anti-IgG in amoebic liver abscess cases.

IgG isolated and purified from a healthy human serum through Sephadex G-200 and protein A CL 4B sepharose chromatography was used for detection of its own antibodies and correlated with the antiamoebic antibody titres in amoebic liver abscess cases. The mean titres with standard deviation of the self reactive antibodies to serum IgG both ALA cases and healthy controls show a highly significant difference, and antiamoebic antibody titres (IgG) are very much correlated with the autoreactive anti IgG titres in amoebic liver abscess cases. This correlation suggests that as antiamoebic IgG levels reach to its maximum, autoreactive anti IgG are produced to switch off antiamoebic anti IgG production in amoebic liver abscess cases.

Animals↗
PubMed1993

Detection of sialic acid in trophozoites of Entamoeba histolytica (NIH:200).

In two successive experiments detection of sialic acid was achieved from trophozoites of axenically grown E. histolytica (NIH:200) using silicic acid column chromatography for the separation of sialosylated lipids and asialosylated lipids from total lipids. Sialic acid of the sialosylated lipids was detected through thiobarbituric acid assay followed by acid hydrolysis. These findings indicate that presence of sialic acid is not only a character of the cystic stage but also that of trophozoites of E. histolytica. Detection of sialic acid confirmed the electronegative charge of the surface membrane (glycocalyx) of E. histolytica trophozoites.

Animals↗
PubMed1992

Autoimmunity in amoebiasis.

Amoebic liver abscess (ALA) and symptomatic intestinal amoebiasis cases were assessed by indirect haemagglutination assay for auto-reactive IgG and IgA class of antibodies in response to healthy human serum IgG and IgA. The present results indicated the presence of autoreactive IgG and IgA class of antibodies in ALA and intestinal amoebiasis respectively.

Autoimmunity↗
PubMed1992

Role of pure and biologically active amoebal RNA in assessment of lymphokines: a report of 55 ALA cases.

Amoebic liver abscess cases (55) were assessed for release of lymphokines (LMIF) using pure and biologically active amoebal RNA of axenic Entamoeba histolytica (NIH: 200) obtained with cesium chloride centrifugation. Lymphokines released by T lymphocytes in response to both amoebal RNA and whole amoebic lysate (WAL) were tested by leukocyte migration inhibition test (LMIT) on blood samples from amoebic liver abscess cases. A significant increase was observed in the release of lymphokine and 100% positivity was observed with amoebal RNA compared to whole amoebic extract with a positivity of only 78%. The difference between means leukocyte migration inhibition of the above two with regards to release of lymphokine was highly significant (P less than 0.001). This shows that patients had high degree of leukocyte sensitization to amoebal RNA of E. histolytica compared to whole amoebic lysate. These findings suggest that the amoebal RNA plays an important role as a potent antigen in the elicitation of cell mediated immune responses in amoebic liver abscess cases.

Adult↗
PubMed1992

Detection of autoreactive antibodies to serum IgG and IgA in amoebic liver abscess cases.

Assessment of autoreactive antibodies in response to healthy human serum IgA and IgG was performed by indirect haemagglutination assay on serum samples from 81 amoebic liver abscess cases for IgA and 70 for IgG. Appropriate controls were taken simultaneously. IgA, IgG were isolated and purified from a healthy human serum through Sephadex G-200 and protein A CL 4B sepharose chromatography. These immunoglobulins were used for the detection of its own antibodies in amoebic liver abscess cases. This revealed that 43.20% and 48.50% of the cases were positive for IgA and IgG respectively, where as only 19.35% and 28.30% of the controls were in positive category (IgA and IgG respectively). The mean titres with standard deviation of the autoreactive antibodies to serum IgA both in ALA cases and controls shows a highly significant difference between tests and controls (P less than 0.001). Similarly the mean titres with standard deviation both in ALA and controls for the serum IgG differed significantly (P less than 0.001). This suggests the presence of autoreactive antibodies against serum IgA and IgG in amoebic liver abscess cases.

Antibodies, Anti-Idiotypic↗
PubMed1991

Detergent dissection of membrane proteins of Entamoeba histolytica and its effect on lymphokine release in in vitro.

Fifty-two amoebic liver abscess cases were assessed for the release of lymphokines (LMIF) using detergent dissected membrane proteins (DDMP) of axenic Entamoeba histolytica (NIH:200) obtained with sodium deoxycholate treatment. Lymphokines release by T lymphocytes in response to both DDMP and whole amoebic lysate (WAL) was tested by leukocyte migration inhibition test on blood samples from amoebic liver abscess cases. A significant increase was noted in the release of LMIF and 100% positivity was observed with DDMP compared to whole amoebic extract with a positivity of 73%. The difference between means of the above two with regards to release of LMIF was found to be highly significant (P less than 0.005). This shows the patients had high degree of leukocyte sensitization to surface antigens of E. histolytica compared to the whole amoebic lysate. These findings suggest that the antigens shed might have important role as a potent antigen in elicitation of CMI response in amoebic liver abscess cases.

Adult↗
PubMedDate not supplied

Immunogenicity of detergent membrane proteins of Entamoeba histolytica.

The lymphokine release and antibody production were assessed in the peripheral blood of 52 and 48 cases of amoebic liver abscess respectively, by employing detergent dissected membrane proteins (DDMP) of axenic Entamoeba histolytica (NIH:200). Lymphokine release by T lymphocytes in response to both DDMP and whole amoebic lysate (WAL) was performed by leukocyte migration inhibition test. A highly increased release of LMIF and 100 per cent positivity was observed with DDMP where as the same for whole amoebic extract, was only 73 per cent. The difference between the means of the above two values with regards to release of LMIF, was found to be highly significant (P less than 0.005). Antibodies production in response to both DDMP and whole amoebic lysate was performed by indirect haemagglutination assay on blood samples from amoebic liver abscess cases. A 53 folds increased titres of IHA and cent percent positivity was observed with DDMP compared to WAL. The difference between mean titres of the above two with regards to detection of antibodies, was found to be highly significant (P less than 0.001). This shows that the patients, had high degree of leukocyte sensitization and production of antibodies which will not be assessed simply with WAL. These findings suggest that the shed material might have important role as a potent antigen in elicitation cell mediated and humoral immune response in amoebic liver abscess cases.

Animals↗