Biomedical subjects

M S Hossain

Publications and source records attributed to M S Hossain.

At least 19 recordsLinked to original sources

PubMed2001

Effects of docosahexaenoic acid on annular lipid fluidity of the rat bile canalicular plasma membrane.

The role of docosahexaenoic acid (DHA) in the fluidity of the annular lipid regions and their associated membrane-bound proteins is still not as well understood as that in the global (bulk) lipid regions. We therefore studied the effects of dietary DHA on the relationship between annular and global lipid fluidity and membrane-bound enzymes such as 5'-nucleotidase and Mg(2)+-ATPase in the rat bile canalicular membrane. Dietary DHA caused significant increases in 5'-nucleotidase and Mg(2)+-ATPase activity and in global and annular lipid fluidity, a higher increase in fluidity in the annular lipids than the global lipids, and a decrease in the cholesterol-to-phospholipid molar ratio in the canalicular membrane. Plasma total cholesterol and LDL cholesterol decreased, and fecal cholesterol increased in the DHA-fed rats. No changes were observed in oxidative markers, but glutathione peroxidase increased in the liver with DHA feeding. Annular lipid fluidity, but not global lipid fluidity, correlated remarkably well with DHA, synchronously with the activities of 5'-nucleotidase and Mg(2)+-ATPase. The data indicate that the DHA-induced increase in annular lipid fluidity is responsible for the increases observed in the enzyme activity. We therefore concluded that the increased activity of membrane-bound enzymes and transporters induced by DHA and the concomitant increase in annular lipid fluidity comprise one of the mechanisms involved in DHA-induced clearance of plasma cholesterol.

5'-Nucleotidase↗

PubMed2000

In vivo acute depletion of CD8(+) T cells before murine cytomegalovirus infection upregulated innate antiviral activity of natural killer cells.

In this study, we investigated the effect of depletion of CD8(+) T cells on the activity of natural killer (NK) cells at an early phase of murine cytomegalovirus (MCMV) infection. For CD8(+) T cell depletion, mice were intraperitoneally treated with anti-CD8 mAb, purified from 2.43 hybridoma, for 2 consecutive days before or after infection. Three days after infection, we found that an acute depletion of CD8(+) T cells before infection caused a significant decrease in the viral load in liver and spleen. This effect coincided with an increase in numbers of CD3(-) NK1.1(+) cells in spleen and their expression of the early activation molecule CD69. Although cytolytic activity of NK cells increased on day 3 of infection in CD8-depleted mice, the level of IFN-gamma decreased in serum and supernatant of cultured spleen cells. In contrast to the effect of acute depletion of CD8(+) T cells before infection, the depletion after infection had no effect on the viral load or number and cytolytic function of NK cells. Lack of effects of CD8(+) T cell depletion on the viral load and NK cytolytic activity is also observed in CD8(+) knockout mice. In conclusion, the results suggest that an acute depletion of CD8(+) T cells before MCMV infection effectively upregulated the antiviral activity of NK cells. This effect appears to be mediated through an increase in numbers, activation and cytolytic activity of NK cells.

Animals↗

PubMed2000

Protective effect of black seed oil from Nigella sativa against murine cytomegalovirus infection.

In this study, antiviral effect of black seed oil (BSO) from Nigella sativa was investigated using murine cytomegalovirus (MCMV) as a model. The viral load and innate immunity mediated by NK cells and Mφ during early stage of the infection were analyzed. Intraperitoneal (i.p.) administration of BSO to BALB/c mice, a susceptible strain of MCMV infection, strikingly inhibited the virus titers in spleen and liver on day 3 of infection with 1x10(5) PFU MCMV. This effect coincided with an increase in serum level of IFN-gamma. Although BSO treatment decreased both number and cytolytic function of NK cells on day 3 of infection, it increased numbers of Mφ and CD4(+) T cells. On day 10 of infection, the virus titer was undetectable in spleen and liver of BSO-treated mice, while it was detectable in control mice. Although spleen of both control and BSO-treated mice showed similar CTL activities on day 10 after infection, serum level of IFN-gamma in BSO-treated mice was higher. Furthermore, BSO treatment upregulated suppressor function of Mφ in spleen. These results show that BSO exhibited a striking antiviral effect against MCMV infection which may be mediated by increasing of Mφ number and function, and IFN-gamma production.

Animals↗

PubMed2000

Characterization of CD4- CD8- CD3+ T-cell receptor-alphabeta+ T cells in murine cytomegalovirus infection.

In this study, we have investigated that after the intraperitoneal infection with murine cytomegalovirus (MCMV), the CD3+ CD4- CD8-(double negative; DN) T-cell receptor (TCR)alphabeta+ T cells increased in peritoneal cavity, liver and spleen in both resistant C57BL/6 and susceptible BALB/c mice. The total cellular population of these cells showed peak levels around day 5 after infection in all the three investigated organs and the following phenotypical and functional characteristics emerged. The peritoneal DN TCRalphabeta+ T cells expressed highly skewed TCRVbeta8 on day 5 after infection compared with the uninfected mice, but those in spleen and liver showed moderate and low skewed TCRVbeta8, respectively. The percentages of NK1.1+ DN TCRalphabeta+ T cells gradually decreased as did modulation of some of their activation markers consistent with an activated cell phenotype. The peritoneal DN TCRalphabeta+ T cells on day 5 after infection expressed the genes of interferon-gamma (IFN-gamma), tumour necrosis factor-alpha, Eta-1 (early T-cell activation-1) and MCP-1 (monocyte chemoattractant protein 1) but lacked expression of interleukin-4 (IL-4). After in vitro stimulation with phorbol 12-myristate 13-acetate and calcium ionophore in the presence of Brefeldin A, higher frequencies of intracellular IFN-gamma+ DN TCRalphabeta+ T cells were detected in all three investigated organs of infected mice compared with those of uninfected mice. Stimulation of peritoneal DN TCRalphabeta+ T cells with plate-bound anti-TCRbeta monoclonal antibodies showed proliferation and also produced IFN-gamma but not IL-4. These results suggest that DN TCRalphabeta+ T cells were activated and may have an antiviral effect through producing IFN-gamma and some macrophage-activating factors during an early phase of MCMV infection.

Animals↗

PubMed2000

Mediation of the immunomodulatory effect of beta-estradiol on inflammatory responses by inhibition of recruitment and activation of inflammatory cells and their gene expression of TNF-alpha and IFN-gamma.

BACKGROUND: Estrogen has long been reported to show immunomodulatory effects on immune responses, yet, its specific anti-inflammatory mechanism is not clear. METHODS: In this study, we analyzed the effects of beta-estradiol (E2), at its contraceptive dose, on both T cell-independent and T cell-dependent inflammations, and the associated immune mechanism, in female mice. The T cell-independent inflammation was locally induced either with an intradermal injection of olive oil in the footpad, or by an intraperitoneal injection of proteose peptone (PP). The T cell-dependent inflammation was induced by an intraperitoneal injection of the purified protein derivatives (PPD). RESULTS: While E2 inhibited olive oil-induced inflammation as monitored by the decrease in footpad swelling, it did not affect the gene expression of monocyte chemoattractant protein-1 and IL-6 by cells at the inflammatory locus. E2 also inhibited PP-induced inflammation as monitored by the decrease in the number of inflammatory peritoneal exudate cells (PEC) coinciding with a marked decrease in the number of macrophages and granulocytes (Gr. 1+). While E2 did not affect the gene expression of monocyte chemoattractant protein-1 and IL-6 by PP-elicited PEC, it decreased both gene expression and production of TNF-alpha. E2 also decreased the number of cells expressing the lymphocyte function-activated protein-1 in PP-elicited PEC, but not for CD62L. In purified protein derivative-induced T cell-dependent inflammation, E2 decreased the total cellularity of PEC and the relative numbers of CD3+ and CD4+ T cells, and the number of cells expressing the lymphocyte activation markers CD40, CD44, CD69 and IL-2Ralpha in PEC. Furthermore, while E2 did not affect the gene expression of the early T lymphocyte activation protein-1 by PEC, it decreased the gene expression of INF-gamma. CONCLUSION: Collectively, the results suggest that E2-mediated inhibition of inflammatory responses may be due to a combination of suppression of homing and activation of inflammatory cells and their production of TNF-alpha and IFN-gamma.

Adjuvants, Immunologic↗

PubMed2000

Vibrio cholerae O139 Bengal: a descriptive study.

A prospective study was conducted to determine the clinical and laboratory characteristics and the clinical course of cholera due to Vibrio cholerae O139 Bengal. The study subjects included 22 adult males with stool culture-proven V. cholerae O139. On enrollment, mean +/- SD concentrations (mmol/L) of serum sodium, potassium, chloride, and bicarbonate were 134 +/- 3, 4 +/- 1, 102 +/- 4, and 13 +/- 4 respectively, and stool sodium, potassium, chloride, and bicarbonate concentrations were 120 +/- 24, 18 +/- 6, 93 +/- 16, and 37 +/- 9 respectively. Seventeen patients (7.8%) had faecal leukocytes ranging from 11 to 50 per high-power field. All V. cholerae O139 isolates (100%) were susceptible to tetracycline, erythromycin, and ciprofloxacin, 92% to furazolidine, and only 5% to trimethoprim-sulphamethaxazole. The median (interquartile) volume of liquid stool during the first 24 hours was 9 (5-12) litre. The median (interquartile) volume of liquid stool and the amounts of intravenous and oral rehydration fluids required during the entire study period were 16 (9-24) litre, 9 (6-18) litre, and 14 (9-20) litre respectively. The median (interquartile) duration of diarrhoea was 80 (48-104) hours. The median (interquartile) duration of excretion of V. cholerae O139 in stool was 5 (3-6) days. Clinical and laboratory features, and case management of cholera due to V. cholerae O139 are very similar to conventional cholera due to V. cholerae O1.

Adolescent↗

PubMed1999

Structural relationship of lambda-type light chains with AL amyloidosis.

Three human amyloidogenic Bence Jones proteins, NIG76 VlambdaII, NIG204 VlambdaI, and NIG250 VlambdaV, were characterized. In a comparative study, three amino acids, Ser-25a, Thr-68, and Val-95, were found to be common to amyloidogenic proteins of the VlambdaII subgroup. NIG204 had an insertion of Pro residue following position 30 (30a). Proteins having an insertion at this position are invariantly amyloidogenic. NIG250 had a characteristic VlambdaV VL domain, with Mcg+ and KERN+ CL domain isotypes. Following the protein DEL, this is the second example of this subgroup. No common residue is found in the other subgroup proteins but unique substitutions do occur. It would seem that any substitution that causes an alteration in the protein conformation may lead to its being more prone to association with the amyloid processes.

Amino Acid Sequence↗

PubMed1999

Association of age-related decrease in platelet membrane fluidity with platelet lipid peroxide.

The influence of age on platelet lipid peroxide (LPO), platelet membrane fluidity and the composition of fatty acid was investigated in female Wistar rats widely ranging in age from 14 to 720 days old. LPO levels were significantly higher (p<0.05) in the platelets of upper age groups than in those of lower age groups, showing a significantly positive correlation with age (r=0.84, p<0.0001). Membrane fluidity, assessed by 1,6-diphenyl-1,3,5-hexatriene (DPH) fluorescence polarization, was significantly reduced with age. The composition of fatty acid demonstrated an age-related elevation (p<0.05) in the unsaturation index. The rises in the LPO levels revealed a significantly positive correlation with DPH-polarization (r=0.73, p<0.0001). Thus our results suggested that the age-related deterioration of platelet membrane fluidity, despite a significant elevation in the unsaturation index, was due to the age-related higher basal levels of LPO in platelets.

Aging↗

PubMed1999

Protective effects of hochu-ekki-to, a Chinese traditional herbal medicine against murine cytomegalovirus infection.

The innate immunity against murine cytomegalovirus (MCMV) at the early phase of infection is mediated by NK cells and macrophages. We studied the effects of hochu-ekki-to (HET), a traditional Chinese herbal medicine, on the regulation of innate immunity mediated by NK cells and macrophages. We found the oral administration of HET to increase both the number of leukocytes in the spleen and liver and the splenic NK cell cytotoxicity associated with the increased induction of serum IFN-alpha/beta after an MCMV infection but it had no effect on liver NK cells. However, no differences were found in the serum IL-12, IFN-gamma, TNF-alpha and nitric oxide (NO) production in the culture of macrophages between the HET- and PBS-treated mice on day 2 after MCMV infection. In addition, HET-treated splenic and peritoneal macrophages were found to show a higher intrinsic resistance against in vitro MCMV infection than that of PBS-treated mice. Therefore, the HET-induced effects on NK cells and macrophages selectively reduced the viral load in the spleen but not in the liver at an early phase of MCMV infection. HET may thus be useful in the treatment of human cytomegalovirus infection which commonly occurs in HIV-infected AIDS patients.

3T3 Cells↗

PubMed1999

Structural relationship of kappa-type light chains with AL amyloidosis: multiple deletions found in a VkappaIV protein.

Two amyloidogenic Bence Jones proteins (Am37 VkappaIV and NIG1 VkappaI) and one non-amyloidogenic protein (NIG26 VkappaIII) were characterized. The protein Am37 had four deletions when compared with the translated germ-line gene sequence: two Ser residues following position 27 (27e, 27f) in CDR1 and two amino acids Pro-44, and Tyr-49 in FR2 were deleted. A strictly conserved salt-bridge-forming amino acid, Asp-82, was replaced by the hydrophobic residue Leu. In a comparative study of amyloidogenic and non-amyloidogenic proteins, five amino acids (Ser-10, Ala-13, Ser-65, Gln-90, and Ile-106) were found to be unique to NIG1 and several other amyloidogenic proteins. Additional substitutions also occur within these proteins. These substitutions might be significant in altering protein folding as well as in contributing to their aggregation as amyloid fibrils.

Amino Acid Sequence↗

PubMed1999

Antioxidative effects of docosahexaenoic acid in the cerebrum versus cerebellum and brainstem of aged hypercholesterolemic rats.

Female Wistar rats (100 weeks old) were divided into two groups; one group was fed a high-cholesterol diet (HC) and the other a high-cholesterol diet plus docosahexaenoic acid (HC-fed DHA rats). Fatty acid concentrations in brain tissues were analyzed by gas chromatography. In the HC-fed DHA rats, brain catalase (CAT), GSH, and glutathione peroxidase (GPx) increased in the cerebrum but not in the brainstem or cerebellum. The rate of increase was 23.0% for CAT, 24.5% for GSH, and 26.3% for GPx compared with that in the HC animals (p < 0.05). In the cerebrum of the HC-fed DHA rats, CAT and GPx increased, with an increase in the ratio of DHA to arachidonic acid. The cerebrum, unlike the other areas of the brain, seems to be more sensitive to DHA in stimulating CAT and GPx. We suggest that DHA plays an important role in inducing an antioxidative defense against active oxygen by enhancing the cerebral activities of CAT, GPx, and GSH.

Aging↗

PubMed1999

The hypotensive effect of docosahexaenoic acid is associated with the enhanced release of ATP from the caudal artery of aged rats.

Fish oils have been shown to lower blood pressure in hypertensive subjects. To determine the mechanism of this hypotensive effect, we examined the effects of docosahexaenoic acid (DHA), one of the (n-3) polyunsaturated fatty acids in fish oil, on blood pressure and on the release of adenyl purines, such as ATP, ADP, AMP and adenosine, from the caudal arteries of aged rats. Aged female Wistar rats (100 wk) were fed a high cholesterol diet and were administered intragastrically ethyl all-cis-4,7,10,13,16,19-docosahexaenoate [300 mg/(kg.d)] for 12 wk (DHA group) or vehicle alone (control group). Compared with the controls, rats supplemented with DHA had significantly greater (10.1%) DHA concentrations in the caudal arteries. This was associated with more total (n-3) arterial fatty acids, a greater unsaturation index of arterial fatty acids, 43.9% lower plasma noradrenaline levels and the repression of the elevation in blood pressure observed with advancing age. The amount of purines released, both spontaneously and in response to noradrenaline, from arterial segments of DHA-supplemented rats was significantly higher than that released from tissues of control rats. Regression analysis revealed significant negative relationships between the total amount of purines released from the artery and the systolic (SBP) and diastolic (DBP) blood pressures. These results suggest that in aged rats, supplementation with DHA alters the membrane fatty acid composition as well as the amount of ATP released from vascular endothelial cells and decreases plasma noradrenaline, and that these factors may ameliorate the rise in blood pressure normally associated with advancing age.

Adenosine Triphosphate↗

PubMed1999

Hypotension induced by exercise is associated with enhanced release of adenyl purines from aged rat artery.

To determine whether the antihypertensive effects of exercise are associated with release of ATP and its metabolites from arteries, we assayed blood pressure and the release of adenine nucleotides and nucleosides from the caudal arteries of exercised and sedentary aged hypercholesterolemic rats. Exercise on a treadmill for 12 wk significantly decreased the rise in systolic and diastolic blood pressure by 7.5 and 15.9%, respectively, with advanced age. The concentrations of oleic, linoleic, and linolenic acids in the caudal artery decreased significantly with exercise, demonstrating an association between exercise and the unsaturation index of caudal arterial fatty acids. The amounts of total adenyl purines released by the arterial segments from exercised rats, both spontaneously and in response to norepinephrine, were significantly greater by 80.0 and 60.7%, respectively, than those released by tissues from sedentary rats. These results suggest that exercise alters the membrane fatty acid composition in aged rats as well as the release of ATP from vascular endothelial cells and that these factors are associated with the regression of the rise in blood pressure normally observed with advanced age.

Adenine Nucleotides↗

PubMed1998

Influence of docosahexaenoic acid on cerebral lipid peroxide level in aged rats with and without hypercholesterolemia.

Female Wistar rats, 100 weeks old, were divided into four groups: one group was fed a high-cholesterol diet, one received a non-cholesterol diet, and the others were fed either a non- or a high-cholesterol diet plus docosahexaenoic acid. The level of lipid peroxide (LPO) in brain tissue was measured with a LPO assay kit. Fatty acid concentrations were analyzed by gas chromatography. Brain LPO in the aged and hypercholesterolemic rats fed docosahexaenoic acid decreased in the cerebrum but not in the brain stem or cerebellum. In the cerebrum, LPO showed a decrease, with an increase in the ratio of docosahexaenoic acid to arachidonic acid. The cerebrum, unlike the other areas of the brain, was more sensitive to docosahexaenoic acid as the concentrations of LPO decreased.

Aging↗

PubMed1998

Protective effects of nicaraven, a new hydroxyl radical scavenger, on the endothelial dysfunction after exposure of pig coronary artery to hydroxyl radicals.

Recently, we have reported that a new synthetic compound, 1,2bis(nicotinamido)-propane (nicaraven), improved cardiac function following preservation and reperfusion. In this study, we investigated the efficacy of nicaraven as a radical scavenger by using an in vitro model of oxidative stress, to clarify mechanisms of the protective effect of this new compound on reperfusion injury in rat heart. Ring segments of epicardial right coronary arteries (RCA) of pig were suspended in organ chambers and exposed to hydroxyl radicals (.OH), generated (by two different systems) by 0.28 mM FeSO4/0.28 mM H2O2 and DHF/Fe3+-ADP (2.4 mM, 43 nM, and 1.56 uM, respectively) to the bathing solution for 60 min. Prior exposure of the coronary arteries to .OH significantly produced right-ward shift of the dose-response curves of the bradykinin-induced endothelium-dependent relaxations (an increase in the ED50 value for bradykinin by 4.37 and 1.98 times than control in two different .OH generating systems, respectively), but did not affect the maximum relaxation responses. The presence of nicaraven (10(-4) and 10(-5) M) in the .OH generating system, shifted the dose-response curves to bradykinin to the control level, suggesting a significant hydroxyl radical scavenging effect of the drug. These results indicate that nicaraven, a new hydroxyl radical scavenger, exhibits a protective effect on hydroxyl radical-induced endothelial dysfunctions of pig coronary artery.

Animals↗

PubMed1998

Detection of Shigellae from stools of dysentery patients by culture and polymerase chain reaction techniques.

In Bangladesh, the isolation rates of Shigella spp. range from 11% to 12% by the conventional culture technique. Since the sensitivity of this technique is low, the polymerase chain reaction (PCR) technique was used for detecting small number of Shigellae from patients' stools. Sensitivity and specificity of the two techniques were also compared. Stool samples were collected from 41 patients with dysentery who attended the Clinical Research and Service Centre of the ICDDR,B: Centre for Health and Population Research. All stool specimens were directly plated onto MacConkey, Salmonella-Shigella, Xylose lysin deoxycholate and Hectoen enteric agar media, and Shigellae were detected following standard procedures. DNA was extracted from the stool samples, and the target sequence of invasive plasmid antigen (ipa)H locus was amplified by PCR with 130 ng each of two primers (primer H8 [5'-GTTCCTTGACCGCCTTTCCGATAC-3'] and primer H15 [5'-GCCGGTCAGCCACCCTA-3']) following standard procedures. The amplified product was hybridized using an ipaH probe. The isolation rates of Shigella dysenteriae type 1, S. flexneri, S. sonnei, and S. boydii were, respectively, 17.1%, 19.5%, 4.9% and 2.4% by the conventional method. The results of the PCR technique showed that 700 bp fragment was generated in 18 of the 18 culture-positive and in 7 of the 23 culture-negative stools. One hundred twenty-three strains of Escherichia coli were also tested by PCR for identifying the enteroinvasive E. coli, but none of them yielded any positive result. This study showed that the sensitivity of the culture technique is 72% and specificity is 100%, when the PCR technique was considered as gold standard. Therefore, the PCR may be considered a more sensitive and specific technique than the conventional culture technique and has the potential to be employed in routine diagnosis of dysentery in clinical centres as well as in epidemiologic studies.

Bacteriological Techniques↗

PubMed1994

Double-blind comparison of oral gentamicin and nalidixic acid in the treatment of acute shigellosis in children.

To compare the efficacy of oral gentamicin with nalidixic acid in the treatment of acute shigellosis, we studied, in a double blind-trial, 79 comparable children with bloody diarrhoea of less than 72 h duration. Of them Shigella spp. were isolated in 71 patients. Patients were randomly assigned to receive either gentamicin 30 mg/kg/day or nalidixic acid 60 mg/kg/day, both given orally in four equal doses for 5 days. Stool frequency differed significantly between the groups from day two until completion of the study. Treatment failure was observed in 14 (42 per cent) patients receiving oral gentamicin compared to none of those with nalidixic acid-sensitive strains of Shigella spp. (P = 0.0002). Although all the shigella isolates were sensitive to gentamicin in vitro, 19 (58 per cent) patients on gentamicin therapy failed to eliminate shigella organisms from stool, compared to none in the nalidixic acid treated group infected with nalidixic acid-sensitive Shigella spp. (P < 0.001). One patient in each group had a bacteriological relapse. We conclude that gentamicin given orally was therapeutically ineffective in the treatment of acute shigellosis.

Acute Disease↗

PubMed1994

Comparison of pivmecillinam and nalidixic acid in the treatment of acute shigellosis in children.

The efficacy of oral pivmecillinam was compared with nalidixic acid in the treatment of acute shigellosis in children 1-8 years of age. In a double-blind trial we studied 80 comparable children with bloody diarrhoea of less than 3 days' duration. Shigella spp. was isolated in 71 children. Patients were randomly assigned to receive either pivmecillinam, 50 mg/kg.day, or nalidixic acid, 60 mg/kg.day, both given orally for 5 days. The stool frequency decreased progressively in both treatment groups. Nalidixic acid failed to eradicate Shigella species in 10 patients, compared with three in the pivmecillinam group (p = 0.04). Similarly, clinical failure was observed in 11 of 37 patients receiving nalidixic acid and in 2 of 26 patients infected with nalidixic acid-susceptible strains as against none in the group receiving pivmecillinam. The results suggest that pivmecillinam given orally was, in fact, more effective than nalidixic acid in the treatment of acute shigellosis in children, particularly when the resistant strains are taken into account.

Acute Disease↗