Biomedical subjects

M M Rahman

Publications and source records attributed to M M Rahman.

At least 91 records · Page 5Linked to original sources

PubMed1997

Physical accessibility guidelines of consumer product controls.

A literature review was undertaken to compile information on the design of consumer product controls (CPCs), concentrating on physical accessibility of electronic devices. Few studies were found that addressed CPC access by people with disabilities; however, information on accessibility for the general population was found. Control guidelines were developed that include information on the application, design, size, force, switch travel, activation/position feedback, spacing, and direction of activation. This information should be helpful to designers of electronic consumer products, researchers interested in product accessibility, and possibly clinicians who are fabricating or modifying equipment for a particular group of people.

Electronics, Medical↗

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

Long-term oral supplementation with iron is not harmful for young children in a poor community of Bangladesh.

The effect of long-term oral iron supplementation on morbidity due to diarrhea, dysentery and respiratory infections in 349 children, aged 2-48 mo, living in a poor community of Bangladesh, was evaluated in this double-blind study. The treatment group received 125 mg of ferrous gluconate (15 mg elemental iron) plus multivitamins and the controls received only multivitamins, daily for 15 mo. House-to-house visits were made on alternate days by trained community health workers for recording symptoms and duration of illnesses and for monitoring medicine intake. Seventy-six percent of the children continued the syrup for over 1 y. No untoward effects were noticed in either treatment group. The attack rates for diarrhea, dysentery and acute respiratory tract infections (ARI) were 3, 3 and 5 episodes per child per year, respectively. Each episode of diarrhea lasted a mean of 3 d, and those of dysentery and ARI, 5 d. The two treatment groups did not differ in the number of episodes, mean duration of each episode, or total days of illnesses due to diarrhea, dysentery and ARI. However, a 49% greater number of episodes of dysentery was observed with iron supplementation in a subset of the study children who were less than 12 mo old (P = 0.03). The results of this study suggest that long-term oral iron supplementation is not harmful for older children in a poor community. Further studies are needed to demonstrate the safety and efficacy of iron administration in young infants.

Administration, Oral↗

PubMed1997

Absorption of nutrients from an energy-dense diet liquefied with amylase from germinated wheat in infants with acute diarrhea.

BACKGROUND: Addition of a small amount of amylase rich flour (ARF) to a thick porridge instantly liquefy the porridge and increase the energy intake even by sick children. The present study examined the absorption of macronutrients and calorie from an energy dense diet liquefied with ARF in children aged 6-11 months with acute watery diarrhea. METHODS: After adequately hydrated with oral rehydration fluid over a period of 24 hours, children were randomly assigned to receive either an ARF treated liquefied porridge (test diet) or a porridge diluted with water (control diet). A 72-hour metabolic balance was performed to determine the absorption of carbohydrate, fat, protein, and calorie. RESULTS: Thirteen infants received the test diet, and 15 infants received the control diet. The intake of protein (g/kg/d), carbohydrate (g/kg.d), fat (g/kg.d) and calorie (kJ/kg.d) were 1.97, 20.6, 4.3 and 548 respectively in the test group and those in the control group were 1.12, 13.3, 2.8 and 356. The stool loss of protein, carbohydrate and fat were comparable in the two groups. The absorption coefficient (%) of carbohydrate, fat and energy were 69.6, 61.3 and 65.4 in the test group and were 73.2, 58.6 and 66.7 in the control group. The coefficient of absorption of protein was significantly higher in the test group (37.7% vs. 21.7%). The mean (95% CI) nitrogen balance (g/kg.d) in the test and control groups were 0.064 (0.026, 0.102) and -0.029 (-0.055, 0.003) respectively. CONCLUSIONS: The results suggest that energy dense diet liquefied with ARF was well absorbed in children with acute diarrhea and there was a positive nitrogen balance that may have a positive impact in preventing weight loss during acute illness.

Absorption↗

PubMed1997

Analysis of the structural gene encoding a hemolysin in Vibrio mimicus.

An environmental isolate of V. mimicus, strain E-33, has been reported to produce and secrete a hemolysin of 63 kDa. The hemolysin is enterotoxic in test animals. The nucleotide sequence of the structural gene of the hemolysin was determined. We found a 2,232 bp open reading frame, which codes a peptide of 744 amino acids, with a calculated molecular weight of 83,903 Da. The sequence for the structural gene was closely related to the V. cholerae el tor hlyA gene, coding an exocellular hemolysin. The amino terminal amino-acid sequence of the 63 kDa hemolysin, purified from V. mimicus, was determined by the Edman degradation method and found to be NH2-S-V-S-A-N-N-V-T-N-N-N-E-T. This sequence is identified from S-152 to T-164 predicted from the nucleotide sequence. So, it seems that the mature hemolysin in V. mimicus is processed upon deleting the first 151 amino acids, and the molecular mass is 65,972 Da. Analyzing the deduced amino-acid sequence, we also found a potential signal sequence of 24 amino acids at the amino terminal. Our results suggest that, like V. cholerae hemolysin, two-step processing also exists in V. Mimicus hemolysin.

Amino Acid Sequence↗

PubMed1997

Absorption of macronutrients and nitrogen balance in children with dysentery fed an amylase-treated energy-dense porridge.

The aim of this study was to determine the absorption of macronutrients and energy from an energy-dense diet liquefied with amylase from germinated wheat (ARF) in children suffering from acute dysentery. Thirty male children aged 6-35 months presenting with acute dysentery were randomly assigned to receive either an ARF-treated porridge or a standard porridge liquefied with water to make its consistency similar to the ARF porridge. After 24-h stabilization a 72-h metabolic balance was performed. Sixteen children received an ARF-treated porridge and 14 received a standard porridge liquefied with water. The mean +/- SD coefficients of absorption (%) of carbohydrate, fat, protein and energy (ARF porridge vs regular porridge) were 81.4 +/- 11 vs 86.9 +/- 7, 86.1 +/- 10 vs 82.8 +/- 15, 57.3 +/- 12 vs 48.4 +/- 24 and 81.4 +/- 9 vs 83.1 +/- 8, respectively. The stool loss of carbohydrate, protein, fat and energy was similar in the two groups. The net absorption of energy was substantially greater in the ARF-fed than regular porridge-fed children (by 28%, p = 0.01). The nitrogen balance was 6.9 +/- 3.4 mg kg(-1) d(-1) in the ARF porridge group and 1.1 +/- 6.7 mg kg(-1) d(-1) in the regular porridge group (p = 0.01). These results show that, despite being hyperosmolar, an amylase-treated liquefied energy-dense porridge is absorbed as well as a regular porridge by malnourished children with severe dysentery. Consequently, its use substantially increased the absorption of a net amount of macronutrients and resulted in a better nitrogen balance. These results further support this innovative approach of feeding sick children in developing countries.

Acute Disease↗

PubMed1997

On-farm monitoring of mouse-invasive Salmonella enterica serovar enteritidis and a model for its association with the production of contaminated eggs.

Mice (Mus musculus) captured in henhouses were assessed for the presence of salmonellae in spleens. Of 621 and 526 spleens cultured during the first and second years of collection, 25.0 and 17.9%, respectively, were positive for Salmonella enterica serovar Enteritidis. Contaminated eggs were cultured from nine houses during the first year of sampling, and for eight of these houses, serovar Enteritidis was recovered from the spleens of mice. Rank sum statistical analysis of positive mouse spleens indicated that three overlapping bacterial populations were present. This pattern of infection was repeated when lipopolysaccharide (LPS) variants were used to infect chicks, and the worst infections were associated with isolates producing high-molecular-weight (HMW) LPS. Mouse isolates were capable of producing unprecedented amounts of HMW LPS as indicated by compositional analysis of six isolates that swarmed across 2% agar, which is a type of bacterial migration dependent upon production of HMW LPS. It is suggested that serovar Enteritidis cultured from the spleens of mice caught on farms will detect strains that are enhanced in their ability to contaminate eggs, in part because they are able to produce HMW LPS.

Animals↗

PubMed1997

Purification and characterization of a hemolysin produced by Vibrio mimicus.

Vibrio mimicus is a causative agent of human gastroenteritis. This pathogen secretes a pore-forming toxin, V. mimicus hemolysin (VMH), which causes hemolysis by three sequential steps: binding to an erythrocyte membrane, formation of a transmembrane pore, and disruption of the cell membrane. VMH with a molecular mass of 63 kDa was purified by ammonium sulfate precipitation and column chromatography with phenyl Sepharose HP and Superose 6 HR. The hemolytic reaction induced by VMH continued up to disruption of all erythrocytes in the assay system. Moreover, VMH that bound preliminarily to erythrocyte ghosts showed a sufficient ability to attack intact erythrocytes. These results suggest reversible binding of the toxin molecule to the membrane. The final cell-disrupting stage was effectively inhibited by various divalent cations. Additionally, some cations, such as Zn2+ and Cu2+, blocked the pore-forming stage at high concentrations. Although VMH could disrupt all kinds of mammalian erythrocytes tested, those from horses were most sensitive to the hemolysin. Horse erythrocytes were found to have the most toxin-binding sites and to be hemolyzed by the least amount of membrane-bound toxin molecules, suggesting that toxin binding to and pore formation on erythrocytes are more effective in horses than in other mammals. Purified VMH induced fluid accumulation in a ligated rabbit ileal loop in a dose-dependent manner. In addition, the antibody against the hemolysin obviously reduced enteropathogenicity of living V. mimicus cells. These findings clearly demonstrate that VMH is probably involved in the virulence of this human pathogen.

Ammonium Sulfate↗

PubMed1997

A virulent isolate of Salmonella enteritidis produces a Salmonella typhi-like lipopolysaccharide.

The lipopolysaccharide (LPS) of Salmonella enteritidis has been implicated as a virulence factor of this organism. Therefore, the LPS from a stable virulent isolate, SE6-E21, was compared with that from an avirulent isolate, SE6-E5. The LPSs were extracted, and the high-molecular-weight (HMW) LPS was separated from the low-molecular-weight (LMW) LPS for both isolates. Both the HMW and LMW LPSs were characterized by glycosyl composition and linkage analyses. Immunochemical characterization was performed by Western blotting using factor 9 antiserum and using S. typhimurium antiserum which contains factors 1, 4, 5, and 12(2). In addition, the polysaccharides released by mild acid hydrolysis were isolated and subjected to hydrolysis by bacteriophage P22, which contains endorhamnosidase activity. The resulting oligosaccharides were purified by using Bio-Gel P4 gel permeation chromatography and characterized by nuclear magnetic resonance spectroscopy, fast atom bombardment mass spectrometry (FAB-MS), tandem MS-MS, and matrix-assisted laser desorption time of flight MS. The results show that the HMW LPS O-antigen polysaccharides from both isolates are comprised of two different repeating units, -[-->2)-[alpha-Tyvp-(1-->3)]beta-D-Manp-(1-->4)-alpha-L-R hap-(1-->3)-alpha-D-Galp-(1-->]- (structure I) and [-->2)-[alpha-Tyvp-(1-->3)]beta-D-Manp-(1-->4)-alpha--L-R hap-(1-->3)-[alpha-D-Glcp-(1-->4)]alpha-D-Galp-(1-->]- (structure II). The LMW LPSs from both isolates contains truncated O-antigen polysaccharide which is comprised of only structure I. In the virulent SE6-E21 isolate, the HMW LPS has a structure I/II ratio of 1:1, while in the avirulent SE6-E5 isolate, this ratio is 7:1. While the 7:1 ratio represents the published level of glucosylation for S. enteritidis LPS as well as for S. enteritidis LPS purchased from Sigma Chemical Co., the 1:1 ratio found for the virulent SE6-E21 is identical to the high level of glucosylation reported for S. typhi LPS. Thus, the LPS from the virulent SE6-E21 isolate produces an S. typhi-like LPS. Furthermore, the amount of O-antigen polysaccharide in SE6-E21 was twice that in SE6-E5.

Antigens, Bacterial↗

PubMed1997

Prevalence of acute respiratory tract infection and its risk factors in under five children.

This study was undertaken to determine the prevalence and risk factors of the disease among under five children in a rural community. Three villages were randomly selected from the Ghoraghat thana of Dinajpur district. All under five children were followed once a month for consecutive four months and all the target variables were checked and recorded in the questionnaire. 566 out of the total of 965 under five children had ARI episodes during the study period. The prevalence of ARI in the community was 58.7%. However, the incidence in both sexes were 14.7%. It was 14.9% and 14.4% in male and female respectively. The mean number of episodes of ARI was 1.75 per child per year. Among studied risk factors, malnutrition (63% vs. 37%), illiteracy (64% vs. 36%), poverty (62% vs. 38%), overcrowding (62% vs. 38%) and parental smoking (61% vs. 39%) were found in significantly higher proportions in ARI victims compared to those without ARI. These observations emphasize the need for research aimed at health system to determine the most appropriate approaches to control acute respiratory infection and thus could be utilized to strengthen the ARI control programme.

Acute Disease↗

PubMed1996

Structural studies of the O-antigenic polysaccharide from an Aeromonas caviae strain.

The structure of the O-antigenic polysaccharide from a strain of Aeromonas caviae, isolated from the stools of a patient with diarrhoea, has been investigated. Sugar analysis, methylation analyses, and a uronic acid degradation together with NMR spectroscopy were the principal methods used. The sequence of the sugar residues could be determined by NOESY and HMBC experiments. It is concluded that the polysaccharide is composed of pentasaccharide repeating units with the following structure: [sequence: see text]

Aeromonas↗

PubMed1996

A Klebsiella pneumoniae strain that shares a type-specific antigen with Shigella flexneri serotype 6. Characterization of the strain and strain and structural studies of the O-antigenic polysaccharide.

A strain of Klebsiella pneumoniae was found as the only isolate with pathogenic potential from the stool of a two-year old patient with diarrhoea. A strong serological cross-reactivity with Shigella flexneri serotype 6 was demonstrated. The cross-reacting antigens were shown to reside in the cell wall lipopoly-saccharide. Studies of the pathogenic potential of the Klebsiella strain showed low level of invasion of HEp-2 cells. However, tests for adherence to HEp-2 cells as well as tests for toxin production were negative. The strain had several small plasmids and was multidrug resistant. These data do not form a sufficient basis for estimating the pathogenic potential of the organism. No K antigen was detected. The structure of the O-antigenic polysaccharide from the K. pneumoniae strain was investigated using methylation analysis, NMR spectroscopy, and Smith degradation as the principal methods. The O-antigenic polysaccharide has the following pentasaccharide repeating unit: -->3)- alpha -L-Rhap-(1-->3)- alpha -L-Rhap-(1-->2)- alpha-L-Rhap- (1-->2)- alpha-L-Rhap-(1-->2)- alpha-L-Rhap-(1-->. This structure is not identical to any of the previously described O-antigens of K. pneumoniae. The strong serological cross-reactivity with the Shigella flexneri serotype 6 O-antigen can most likely be attributed to the structural element alpha-L-Rhap-(1-->2)- alpha -L-Rhap present in the O-polysaccharide repeating unit of this serotype. Antiserum raised against the K. pneumoniae strain also agglutinated S. dysenteriae serotype 1 and strains of all different serotypes of S. flexneri. The Shigella strains contain the structural element alpha-L-Rhap-(1-->3)- alpha-L-Rhap in their O-antigen polysaccharides which may be responsible for the observed cross-reactivity.

Bacterial Adhesion↗

PubMed1996

Relationship between survival status of first child and subsequent child death.

This paper examines the association between infant mortality of the first born and subsequent children using data from rural Bangladesh collected during the period 1971-82. It shows that birth spacing and age of mother at the time of the second birth are important predictors of the survival status of the first child. The findings are discussed in terms of policy implications.

Bangladesh↗

PubMed1996

A novel relationship between O-antigen variation, matrix formation, and invasiveness of Salmonella enteritidis.

Salmonella enterica Enteritidis in chickens serves as a reservoir for salmonellosis in humans and the structure of its lipopolysaccharide (LPS) has been used to assess invasiveness. Culture from chick spleens generated colonies with an unusual wrinkled morphology, and it is designated the lacy phenotype. The characterize the nature of the morphological change, three isogenic variants were compared. Only the lacy phenotype produced a temperature-dependent cell surface matrix composed of several proteins in association with LPS high molecular weight O-antigen. Flagellin and a 35 kDa protein were identified as specific proteinaceous components of matrix. Both proteins cross-reacted with a monoclonal antibody previously determined to specifically detect the g-epitope of the Enteritidis monophasic flagella (H-antigen). These results suggest that O-antigen in association with protein contributes to cross-reactivity between molecules. The lacy phenotype was more organ invasive in 5-day-old chicks than isogenic variants producing low molecular weight O-antigen. However, it was no more efficient at contaminating eggs after oral inoculation of hens than a variant that completely lacked O-antigen, thus the lacy phenotype is classified as an intermediately invasive organism. The distinctive colonial phenotype of SE6-E21lacy was used to investigate environmental factors that decreased O/C ratios and contributed to attenuation. In so doing, it was found that growth in complement at 46 degrees C caused matrix producing cells to hyperflagellate and migrate across agar surfaces. These results suggest that the structure of O-antigen might influence the secretion and/or the function of Enteritidis cell-surface proteins. The data also reveal a greater heterogeneity than has been assumed in the phenotype, and possibly the infectious behaviour, of Enteritidis.

Animals↗

PubMed1996

Separation of bacterial capsular and lipopolysaccharides by preparative electrophoresis.

Preparative gel electrophoresis was used to separate and purify extracellular, capsular and lipopolysaccharides (EPSs, CPSs, and LPSs, respectively) from crude bacterial extracts. The procedure effectively separates CPS from LPSs. In addition discreet size ranges of these various polysaccharides can be isolated. The 'rough' (R-type), 'smooth' (S-type), and 'semi-smooth' LPSs were separated from one another. In addition different size classes of 'semi-smooth', or S-type LPS, can be separated. This procedure was demonstrated for diverse bacterial species, including the soil bacteria Rhizobium fredii, and the enteric bacterial species, Salmonella enteritidis and Proteus mirabilis. In the latter case, it was also possible to separate capsular polysaccharide from its lipid-bound form.

Electrophoresis, Polyacrylamide Gel↗

PubMed1996

Helicobacter pylori infection in the young in Bangladesh: prevalence, socioeconomic and nutritional aspects.

BACKGROUND: The gastric acid barrier, an important host defence against small bowel infection, may be compromised by infection with Helicobacter pylori. In developing countries, H. pylori infection occurs early in life and prevalence of hypochlorhydria is high particularly in the malnourished, which may predispose a child to repeated gastrointestinal infection and diarrhoea. Diarrhoea being a leading cause of childhood mortality and morbidity in developing countries, we investigated the prevalence of H. pylori infection in children in a poor Bangladeshi community and explored its association with socioeconomic and nutritional status. METHODS: The study was conducted in a poor periurban community among 469 children aged 1-99 months. Parents were interviewed using a questionnaire. To detect active infection with H. pylori a 13C-urea breath test was performed and weight was recorded on a beam balance with a sensitivity of 20 g. RESULTS: In all, 61% of 36 infants aged 1-3 months were positive for H. pylori; this rate dropped steadily with increasing age and was 33% in 10-15 month old children and then rose to 84% in 6-9 year olds. Overall H. pylori infection had no association with nutritional state of the child, or family income but the infection rate was 2.5 times higher in children of mothers with no schooling. CONCLUSIONS: The H. pylori infection rate is very high in early infancy in a poor periurban community of Bangladesh. The reason for a drop in the infection rate in late infancy is unclear but could be due to initial clearance of the infection by the body's defence mechanisms but with possible alteration of the gastric mucosa which sustains infection. Maternal education may be protective and may operate through some unidentified proximate behavioural determinants. The rate of H. pylori infection in infants and young children may predispose them to repeated gastrointestinal infection and diarrhoea.

Age Factors↗

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↗