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Biomedical subjects

A Molla

Publications and source records attributed to A Molla.

At least 73 records · Page 4Linked to original sources
PubMed1990

Immunogenicity and antigenicity of conserved peptides from the envelope of HIV-1 expressed at the surface of recombinant bacteria.

We expressed peptides from the HIV-1 envelope protein at the surface of Escherichia coli by genetic insertions into an exposed loop of the outer membrane protein LamB. Recombinant bacteria expressing eight peptides from gp110 (pep1-pep8), conserved between HIV-1 and HIV-2, were used as live immunogens in rabbits by the intravenous route. The eight constructions elicited anti-LamB antibodies, showing that the hybrid proteins were immunogenic. One of them, LamB-pep8, gave rise to antibodies able to react with gp160 and to neutralize HIV-1 in vitro. We also show that this type of recombinant E. coli can provide a convenient reagent to monitor and characterize specific antibodies. Recombinant clones were used to test sera of seropositive individuals, as well as to narrow down the monoclonal antibody 110-1 recognition site to a cluster of eight residues at the carboxy-terminal end of gp110.

Amino Acid Sequence↗
PubMed1990

Inactivation of chemotactic activity of C5a by the serratial 56-kilodalton protease.

The effects of the 56-kilodalton protease (56K protease) from Serratia marcescens on complement-derived chemotactic activity were examined. Fresh human serum was incubated with zymosan to produce C5a. This activated serum was then incubated with various concentrations of 56K protease, and the chemotactic activity of mouse peritoneal exudate polymorphonuclear leukocytes (PMN) and macrophages was evaluated. A significant dose-dependent decrease of chemotactic activity was observed after protease treatment. Furthermore, treatment of human recombinant C5a with 56K protease at a dose of 1.0 microgram/ml resulted in a complete loss of chemotactic activity. When the living bacteria of the virulent strain, which produced about 10 times more protease than did the less virulent strain, were injected intraperitoneally into mice, the magnitude of infiltration of polymorphonuclear leukocytes into the peritoneal cavity was much lower than that caused by the less virulent strain. Because complement-dependent chemotactic activity is an initial response to bacterial infection, these results suggest indirect pathogenic functions of serratial proteases that suppress chemotactic activity.

Blood Bactericidal Activity↗
PubMed1990

Serum cholesterol in neonates and their mothers. A pilot study.

Reports from the Aga Khan University indicate that 58% of 400 school children studied had undesirably high serum cholesterol levels. The present study was undertaken to determine whether the high cholesterol levels are present at birth and to determine the relationship between cord blood, maternal blood cholesterol and maternal diet. Cord blood from 58 neonates and fasting venous blood from 45 mothers were analyzed from total serum cholesterol. Mothers were interviewed regarding their usual diet during pregnancy. Mean cord blood cholesterol was 56.90 mg/dl (range 26 to 123 mg/dl). Mean maternal blood cholesterol was 232.4 mg/dl (range 141-382 mg/dl). Mean maternal intake of cholesterol was 457 mg (recommended level less than or equal to 300 mg/day). There was no significant co-relation between cord blood cholesterol and maternal blood cholesterol or maternal intake of cholesterol. Eighteen percent of the mothers reported a strong family history of hypercholesterolemia and/or heart disease, but this genetic tendency was not observed in the blood cholesterol level at birth indicating that environmental factors namely diet may have a prime role in determining serum cholesterol levels in childhood.

Cholesterol↗
PubMed1990

Serum alkaline phosphatase in apparently healthy Karachi population.

Serum alkaline phosphatase (AP) was estimated in a total of 786 (418 males and 386 females) apparently healthy people aged between 1-75 years selected randomly from a sample of the Karachi population. Reference ranges for AP level were obtained for the males and females stratified into ten successive age groups. The study population was also divided into two main age groups, a paediatric aged between 1-14 years and an adult group aged between 15 to over 50 years to see if the mean AP levels differ significantly between the two groups. Mean AP level for the male paediatric age group was 225 IU/L, significantly higher (P less than 0.005) than those of the male adult mean level of 83 IU/L. Similarly the mean AP levels for the paediatric female age group was 205 IU/L significantly higher (P less than 0.005), compared to the mean AP level of 67 IU/L obtained for the female adult age group.

Adolescent↗
PubMed1990

Role of glucose polymer (cereal) in oral rehydration therapy.

The standard packaged glucose-based oral rehydration solution (ORS) provides optimal rehydration of acute diarrhea from any cause, but it does not reduce the volume, frequency, or duration of diarrhea. A new ORS formulation has been developed in which glucose is replaced by 50 to 60 gm of cereal flours, such as rice, wheat, maize, sorghum, or millet, or equivalent amounts of noncereal staples, such as boiled potato or plantain. In a clinical trial in children suffering from acute diarrhea, the staple-based or polymer-based ORS achieved a 40% to 60% reduction in the stool volume compared with the standard ORS. A three-cell longitudinal study in rural Bangladesh involving 2,000 children aged 1 to 4 years demonstrated the superior efficacy of rice ORS compared with glucose ORS or no ORS. The cumulative recovery rate on day 3 was 66%, 24%, and 11% in the rice ORS, glucose ORS, and comparison groups, respectively. The study suggests that staple-based or food-based ORS is the optimal treatment of diarrhea.

Diarrhea↗
PubMed1990

Blood lipids in a healthy Karachi population.

Serum levels for cholesterol and triglycerides were estimated in an apparently normal healthy population of Karachi, aged between 4 and 59 years. In total, there were 632 subjects, 322 males and 310 females. Hypercholesterolemia was defined as a cholesterol level greater than 6.2 mmol l-1 (240 mg dl-1) in subjects above 20 years of age. In the age groups 20-39 and 40-59 years hypercholesterolemia was present in 26-41% of the males and 10-38% of the females. When triglyceride levels of more than 2.8 mmol l-1 (250 mg dl-1) were taken as abnormal for healthy males and females, 0-2% of the females and 10-25% of the males above 20 years of age were hypertriglyceridemic. The mean cholesterol levels in the age groups 4-9 and 10-19 years varied from 4.4 to 4.9 mmol l-1 (169.8 to 189.1 mg dl-1).

Adolescent↗
PubMed1989

Pathogenic potentials of bacterial proteases.

Six separate molecular mechanisms for pathogenesis attributed to bacterial proteases are described. (I). Enhancements of vascular permeability and edema formation which result from the activation of kinin generating cascade such as Hageman factor by the proteases. (II). Degradation of defense oriented proteins including IgG and IgA as well as destruction of structural matrices such as fibronectin, proteoglycan and collagen. (III). Inactivation of complement system and generated chemotactic factor from C3 and C5. (IV). Degradation of regulatory plasma protease inhibitors (serpins) including alpha 1-protease inhibitor, alpha 2-macroglobulin (alpha 2M), C1-esterase inhibitor, alpha 2-antiplasmin and antithrombin-III. (V). The protease forms a transitory stable enzyme/inhibitor(alpha 2M) complex. It binds to and internalizes into the cells which possess alpha 2M-receptor such as fibroblasts via the alpha 2M-receptor, and the protease activity is regenerated in cells, and subsequently intracellular integrity is destroyed resulting in cell killing. (VI). The serratial 56 kDa (56K) protease is found to potential viral yield 100 fold more when influenza virus infected mice were subjected to administrations of this protease intranasally. This results in rapid and much elevated lethality.

Animals↗
PubMed1989

Antibodies against synthetic peptides and the topology of LamB, an outer membrane protein from Escherichia coli K12.

LamB, an outer membrane protein from Escherichia coli K12, is involved in the transport of maltose and maltodextrins across the outer membrane and constitutes a receptor for a number of bacteriophages. A recent folding model proposes that LamB spans the outer membrane through a number of transmembranous segments separated by regions exposed either to the cell exterior or to the periplasm. This model is essentially based on predictions of structure and genetic arguments relying on the hypothesis that the mutations studied did not alter the folding of the protein. In order to obtain direct evidence with the unaltered protein, we elicited polyclonal antibodies against synthetic peptides corresponding to several LamB sequences. We chose four regions. Three of them [aa 147-161 (peptide 2), aa 371-385 (peptide 3), and aa 399-413 (peptide 4)] are predicted to face the outside of the cell, and the fourth (aa 19-33 (peptide 1)] is predicted to be periplasmic. By immunoblotting against extracts of various mutants, these antibodies were shown to be specific for LamB and targeted to the selected regions. In some cases, the recognition sites for antibodies were narrowed down to parts of a region. In vivo, on intact cells, anti-peptides 2, 3, and 4 reacted with LamB in an ELISA; this confirmed that regions of peptide 2 and 3 are located, at least in part, at the cell exterior and provided the first proof for a similar, situation of the region of peptide 4. Under the same conditions, anti-peptide 1 did not react with LamB.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1989

Food-based oral rehydration salt solution for acute childhood diarrhoea.

The efficacy in acute childhood diarrhoea of oral rehydration therapy (ORT) based on staple foods (maize, millet, wheat, sorghum, rice, or potato) was compared with that of standard ORT based on glucose. 266 children aged 1-5 years, with a history of acute diarrhoea for 48 h or less, moderate to severe dehydration, and no complications, were assigned to treatment with one of the food-based oral rehydration salt solutions (ORS) or standard ORS. The mean stool output over the first 24 h of treatment in the group receiving standard ORS was significantly higher than that of any other treatment group, and the groups receiving food-based ORT showed substantial reductions in stool output compared with the standard ORT group. Abnormalities in electrolyte concentrations were corrected in all treatment groups with similar efficiency. The digestibility of the food-based ORS was assessed by the stool pH, glucose content before and after acid hydrolysis, and osmolality; there were no significant differences between the standard ORS and food-based ORS groups. Food-based ORT should be more acceptable to users in developing countries since the mixtures are similar to traditional weaning foods and since, unlike standard ORT, it reduces stool output substantially.

Acute Disease↗
PubMed1989

Activation of hageman factor and prekallikrein and generation of kinin by various microbial proteinases.

Activation of the Hageman factor-kallikrein-kinin system by serratial 56-kDa proteinase was previously demonstrated (Matsumoto, K., Yamamoto, T., Kamata, T., and Maeda, H. (1984) J. Biochem. (Tokyo) 96, 739-749; Kamata, R., Yamamoto, T., Matsumoto, K., and Maeda, H. (1985) Infect. Immun. 48, 747-753). To investigate whether the activation of the system is specific for 56-kDa proteinase or is found similarly with other microbial proteinases, 11 proteinases of microbial origins were studied; the 56-kDa proteinase was the control. For in vitro studies, activation of guinea pig Hageman factor and prekallikrein was examined in purified systems as well as in plasma as a zymogen source. Specific antibodies and inhibitors confirmed the activation steps of the cascade. In the in vivo study the enhancement of vascular permeability in guinea pig skin and its sensitivity to inhibitors of activated Hageman factor, plasma kallikrein, or a kininase were examined. The results from the in vivo experiments were consistent with those in vitro. Taking all the data together, we classified the 11 microbial proteinases into three groups as follows: 1) Serratia marcescens 56-, 60-, and 73-kDa proteinases, Pseudomonas aeruginosa alkaline proteinase and elastase, and Aspergillus melleus proteinase (this group activated Hageman factor but not prekallikrein); 2) Vibrio vulnificus proteinase, subtilisin from Bacillus subtilis, and thermolysin from Bacillus stearothermophilus (this group activated both Hageman factor and prekallikrein); 3) Streptomyces caespitosus proteinase and V8 proteinase from Staphylococcus aureus (this group activated neither Hageman factor nor prekallikrein, but generated kinin from high molecular weight kininogen directly).

Animals↗
PubMed1989

Cytotoxicity of bacterial proteases in various tumor cells mediated through alpha 2-macroglobulin receptor.

The binding and cytotoxicity of a complex of fluorescein isothiocyanate-labeled 56K protease and alpha 2-macroglobulin (alpha 2M) were determined by using various human and rodent tumor cell lines. The binding was higher at 37 degrees C than at 4 degrees C; a rapid and progressive uptake that was time dependent was noted at 37 degrees C, whereas no uptake was observed at 4 degrees C, which indicated temperature-dependent internalization. The binding was highest in the fibroblastic and adenocarcinoma cells, and lowest in squamous and epidermoid cells. The Scatchard plots for the binding isotherms were linear, with an apparent Kassoc 1.17 to 2.99 x 10(-8) M for those cells with high alpha 2M receptor. The number of binding sites (alpha 2M receptor) per cell was 1.3 to 4.75 x 10(6). Values for squamous/epidermoid cells were much lower or undetectable. Fluorescent antibody staining indicated that MCF-7 and other cells with alpha 2M receptor internalized the protease-alpha 2M complex, whereas B-16 melanoma, which has little alpha 2M receptor on the cell surface, did not. Furthermore, when the cytotoxicity of this complex was compared with that of different cell lines, the cells with high rates of uptake of the complex required only a low concentration of the protease and vice versa. These results suggest a possible mechanism of cytotoxic action of protease: alpha 2M receptor-mediated endocytosis of the complex followed by destruction of cellular integrity after regeneration of proteolytic activity. Thus, cells with more alpha 2M receptor require only a low dose for cytotoxic action when compared with cells with little alpha 2M receptor.

Adenocarcinoma↗
PubMed1989

Antibody response to a foreign epitope expressed at the surface of recombinant bacteria: importance of the route of immunization.

A genetic procedure has been previously established to expose a foreign epitope at the surface of Escherichia coli by using the outer membrane LamB protein as a carrier. A portion of the pre-S2 region of hepatitis B virus, residues 132-145, has been inserted at amino acid position 153 of the LamB protein, in a cell surface exposed loop. In the present study, we have analysed the antibody responses induced by these recombinant bacteria (live, heat-killed or sonicated) depending upon the route of immunization. The intravenous (i.v.) or intraperitoneal (i.p.) administration of the live recombinant bacteria to mice induced the synthesis of antibodies against both the inserted peptide and the native LamB protein. The antibodies raised recognized HBsAg particles. These mice also had high titres of antibodies against E. coli antigens (as determined using a crude bacterial sonicate). In contrast, mice immunized subcutaneously (s.c.) did not develop antibodies against the pre-S2 peptide nor against the HBsAg particles. Their anti-LamB responses were low compared with the response of mice immunized by the parenteral route. Interestingly, s.c. or i.v. immunizations induced comparable levels of anti-E. coli antibodies. Thus, the antibody response to the inserted peptide generally parallels the response to the LamB protein (and not to the bulk of E. coli antigens). However, this treatment corresponding to a 'pre-processing' of the recombinant bacteria was not sufficient to obtain an anti-peptide response following s.c. immunization.

Animals↗
PubMed1989

Turning off the diarrhea: the role of food and ORS.

Ninety-three boys aged 5 years or less who had diarrhea due to Vibrio cholerae were randomly assigned to treatment with glucose oral rehydration salt (ORS) or rice-based ORS. For the first 24 h, ORS only was given to all the patients. During the next 24 h, ORS and normal food were given. The efficacy of the two types of ORS was compared in terms of ORS intake, stool output, change in hematocrit reading, serum specific gravity, and increase in body weight. At the end of the first 24 h of treatment, a 50% reduction in ORS intake and stool output was observed in the 47 patients randomly assigned to receive rice ORS as compared with the 46 patients who received glucose ORS. During the second 24 h of treatment, a significant reduction in the stool output was noticed in the glucose ORS group, making the efficacy of glucose ORS equal to that of rice ORS. The study suggests that normal food can impart some of the superiority of "super" ORS to standard glucose ORS with regard to reduction of stool volume.

Acute Disease↗
PubMed1989

Inactivation of various proteinase inhibitors and the complement system in human plasma by the 56-kilodalton proteinase from Serratia marcescens.

The interaction of the 56-kilodalton (kDa) proteinase from Serratia marcescens with human plasma activated C1 (C1) inhibitor, alpha 2-antiplasmin, and antithrombin III was investigated. The 56-kDa proteinase was not affected by these inhibitors; on the contrary, all the inhibitors were inactivated by the 56-kDa proteinase within 2 to 6 h. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that all three inhibitors showed decreases in molecular weight of approximately 8,000 to 10,000 as a result of proteolytic cleavage by the 56-kDa proteinase. The 56-kDa proteinase also inactivated serum complement within 2 to 6 h. The loss of inhibitory activity caused by the 56-kDa proteinase, together with the effects of endogenous serine proteinases, may facilitate tissue destruction and inflammation.

Complement C1 Inactivator Proteins↗
PubMed1989

Molecular mechanism of complex infection by bacteria and virus analyzed by a model using serratial protease and influenza virus in mice.

We examined the effect of a serratial exoprotease on the pathogenesis of influenza virus infection in mice as a model of complicated respiratory infection by bacteria and virus in humans. The 56-kilodalton (56-kDa) protease from Serratia marcescens was administrated intranasally to mice at a dose of 10, 20, or 40 micrograms from day 0 to day 3 after inoculation of the influenza virus. Administration of the protease resulted in remarkable enhancement of the lethal effect of the virus and enhancement of pathological changes in the lungs. Influenza virus replication, determined by plaque-forming assay, was accelerated by the protease. Namely, we found a 100-fold increase in virus yield by day 2. The 56-kDa protease caused generation of plasmin activity in the lungs. In vitro experiments showed that plasmin greatly enhanced the yield of influenza virus, although the effect of the 56-kDa protease by itself was much lower than that of plasmin. Furthermore, the 56-kDa protease could induce plasmin production indirectly via activation of plasminogen by the Hageman factor-dependent cascade in the in vitro system. We conclude that this major serratial exoprotease has a deleterious effect on mice infected with influenza virus and that this effect seems to result from enhancement of viral growth by indirect acceleration of plasmin generation induced by the protease.

Animals↗
PubMed1989

Cereal based oral rehydration solutions.

A total of 257 boys (age range 4-55 months), who had acute diarrhoea with moderate to severe dehydration, were randomly assigned to treatment with either the World Health Organisation/United Nations Childrens Fund (WHO/Unicef) recommended oral rehydration solution or cereal based oral rehydration solution made either of maize, millet, sorghum, or rice. After the initial rehydration was achieved patients were offered traditional weaning foods. Treatment with oral rehydration solution continued until diarrhoea stopped. Accurate intake and output was maintained throughout the study period. Efficacy of the treatment was compared between the different treatment groups in terms of intake of the solution, stool output, duration of diarrhoea after admission, and weight gain after 24, 48, and 72 hours, and after resolution of diarrhoea. Results suggest that all the cereal based solutions were as effective as glucose based standard oral rehydration solution in the treatment of diarrhoea.

Dehydration↗
PubMed1989

Efficacy of a home made quality control serum.

With increasing automation in Clinical Laboratories, the requirements for quality control material have greatly increased in order to monitor performance. The constant use of commercial control material is not economically feasible for many countries because of non-availability or the high cost of these materials. Here we describe a simple technique to prepare Home Made Quality Control serum using blood from polycythaemic patients. This preparation is stable for about six months without any alterations in the concentration of any of the chemical constituents. Extensive use of Home Made Quality Control sera in our laboratories have saved about 69% of the amount spent on the commercial material without any compromise in quality of the laboratory performance.

Blood↗