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Biomedical subjects

M Ishaque

Publications and source records attributed to M Ishaque.

At least 37 records · Page 2Linked to original sources
PubMed1989

Direct evidence for the oxidation of palmitic acid by host-grown Mycobacterium leprae.

Oxidation of palmitic acid by whole-cell suspensions of Mycobacterium leprae free from host tissues was investigated using manometric techniques. After a lag period of about 6-8 h, M. leprae suspensions catalysed an active oxidation of palmitic acid, and the oxidative process (oxygen uptake) was quite sensitive to rotenone, atabrine, amytal, antimycin A and cyanide. The spectrophotometric observations indicated that the M. leprae cytochrome system, under anaerobic conditions, was reduced in the presence of palmitic acid which was completely oxidized by oxygen. These data provide direct evidence that M. leprae cells are capable of oxidizing palmitic acid, and that oxidation is mediated by the electron transport system using oxygen as the terminal electron acceptor.

Animals↗
PubMed1989

Duodenal and antral mucosal prostaglandin E2 synthesis in a study of normal subjects and all stages of duodenal ulcer disease treated by H2 receptor antagonists.

We tested the hypothesis that the production of prostaglandin E2 (PGE2) is impaired in duodenal ulcer disease and affected by treatment and healing. This was investigated by a study of maximal PGE2 synthesis rates in duodenal and antral mucosal biopsies obtained at endoscopy. The patients were divided into three groups. Group (a): endoscopically normal controls (n = 56); group (b): treatment controls (non-DU disease: gastric ulcer or oesophagitis treated by histamine H2 receptor antagonists) (n = 41); and group (c): patients with DU disease (n = 183) further subdivided into group (c1) active ulcer not on treatment (n = 47), (c2) treated active ulcer (n = 35), (c3) healed ulcer on treatment (n = 86), and (c4) healed ulcer not on treatment (n = 15). Group (a) synthesised (mean (SD] 106.6 (39.0) pg PGE2/mg wt of tissue from the duodenal bulb and 129.9 (56.9) from the second part of the duodenum. No difference was found between group (a) and (b) at either site. Group (c1) ulcer rim made 49.8 (22.7) and at all stages ulcer rim and scar made less than the control duodenal bulb (p less than 0.02). Uninvolved duodenal bulb form groups (c1) (63.4 (31.0], (c2) (83.6 (38.5], and (c3) (81.5 (31.1], however, also made significantly less than controls (p less than 0.02) and a similar though non-significant trend was seen in group (c4). Biopsies from the second part of the duodenum did not synthesise significantly less than the control group but a similar trend was noticed at each stage of ulcer treatment. Biopsies of control antrum synthesised 124.5 (32.2) but only 93.7 (44.2) in group (cl) (p < 0.005). All stages of duodenal ulcer healing were associated with a decreased capacity to synthesise the major prostaglandin PGE2 at the ulcer site and the uninvolved duodenal bulb and, in acute untreated duodenal ulcer, the uninvolved antrum. This decreased capacity may be the consequence of the disease process itself and not secondary to the treatment, indicating a basic pathophysiological abnormality which may explain the characteristic tendency of the disease to relapse.

Adult↗
PubMed1987

Microbiological Degradation of Malodorous Substances of Swine Waste under Aerobic Conditions.

Phenol, p-cresol, and volatile fatty acids (VFA; acetic, propionic, isobutyric, butyric, isovaleric, and valeric acids) were used as odor indicators of swine waste. Aeration of the waste allowed the indigenous microorganisms to grow and degrade these malodorous substances. The time required for degradation of these substances varied according to the waste used, and it was not necessarily related to their concentrations. Using a minimal medium which contained one of the malodorous compounds as sole carbon source, we have selected from swine waste microorganisms that can grow in the medium. The majority of these microorganisms were able to degrade the same substrate when inoculated in sterilized swine waste but with an efficiency varying from one strain to the other. None of these strains was able to degrade all malodorous substances studied. Within 6 days of incubation these selected strains degraded the following: Acinetobacter calcoaceticus, phenol and all VFA; Alcaligenes faecalis, p-cresol and all VFA; Corynebacterium glutamicum and Micrococcus sp., phenol, p-cresol, and acetic and propionic acids; Arthrobacter flavescens, all VFA. On a laboratory scale, the massive inoculation of swine waste with C. glutamicum or Micrococcus sp. accelerated degradation of the malodorous substances. However, this effect was not observed with all of the various swine wastes tested. These results suggest that an efficient deodorization process of various swine wastes could be developed at the farm level based on the aerobic indigenous microflora of each waste.

Journal Article↗
PubMed1984

Cytochrome system in cultivated Mycobacterium lepraemurium.

The respiratory pigments of cell suspensions of Mycobacterium lepraemurium cultivated on Ogawa egg-yolk medium were investigated spectrophotometrically. The results obtained showed that whole cell suspensions of both Kumato and Hawaiian strains contained flavins, cytochromes of the a2 and b type, as well as a CO-binding pigment similar to cytochrome o. The whole cell suspensions of M. lepraemurium did not show detectable quantities of c type cytochrome. However, cytochrome c was present in small amounts, and its presence became evident in the dithionite-reduced minus oxidized difference spectra of pyridine haemochromogens prepared from in vitro grown cells of M. lepraemurium.

Carbon Dioxide↗
PubMed1983

Impairment of virulence of in vitro subcultures of Mycobacterium lepraemurium.

Mycobacterium lepraemurium was cultivated in vitro on Ogawa egg-yolk medium. The pathogenicity of the third and eighth subcultures for C3H and C57BL mice was compared with that of in vivo grown murine bacilli by evaluating the mean survival time of infected mice. The results strongly suggest that a significant drop of virulence occurs during the in vitro cultivation of M. lepraemurium.

Animals↗
PubMed1983

Respiratory activities of in vitro grown Mycobacterium lepraemurium.

Mycobacterium lepraemurium was cultivated on Ogawa egg-yolk medium and its respiratory activities using several substrates were investigated. Glycerol and succinate were oxidized at a slow rate by the cell-free extracts prepared from in vitro grown Hawaiian and Keishicho strains of M. lepraemurium. None of the other intermediates of the glycolysis cycle as well as of the tricarboxylic acid cycle was oxidized by the whole cell suspensions or cell-free extracts. Likewise, many sulfur compounds such as cystine, mercaptosuccinate, monothioglycerol, thioacetate, etc., were inactive. However, sulfhydryl compounds such as L-cysteine, D-cysteine, DL-cysteine, dithioerythritol, dithiothritol, and DL-penicillamine were actively oxidized. Yeast extract was also readily oxidized by cell suspensions of in vitro grown M. lepraemurium. Tween 80 was very poorly oxidized by whole cell suspensions but the cell-free preparations catalyzed an active oxidation of Tween 80. While bovine serum albumin was oxidized at a slow rate by cell-free extracts, egg albumin was inactive. The thiol-binding agents, p-hydroxymercuribenzoate and N-ethylmaleimide were effective inhibitors of succinate and NADH oxidation, thus indicating the involvement of sulfhydryl compounds in the metabolism of M. lepraemurium.

In Vitro Techniques↗
PubMed1982

[Pathogenicity in the rat of Mycobacterium lepraemurium cultivated in vitro].

The pathogenicity in Sprague-Dawley rats of Mycobacterium lepraemurium cultivated on egg-yolk medium was investigated. The results show that in vitro grown cultures provoked hugh subcutaneous lepromata in rats similar to those produced by the in vivo grown M. lepraemurium. The acid-fast bacilli isolated from lepromata of rats infected with the in vitro or in vivo grown cultures were microscopically and histopathologically identical to each other.

Animals↗
PubMed1982

Mycobacteria of Mycobacterium scrofulaceum type isolated from rat or mice lepromata are not the aetiologic agents of murine leprosy.

Mycobacterial strains M.M4 and M.EY3 were isolated from a mouse leproma, respectively, on Kl-1 and Ogawa egg-yolk medium. Strain M.M4 was scotochromogenic and produced a yellow pigment. Young cultures were non-acid-fast and became acid-fast during the exponential growth phase. Primary cultures of strain M.M4 did not grow on conventional culture media. However, the subcultures grown in Kl-1 medium were easily subcultured in the homologous media as well as on Lowenstein, Sauton and Dubos media. Cultures M.M4 were insensitive to isoniazid and p-nitrobenzoic acid. Both scotochromogenic strains M.R56 and M.M4 did not produce murine leprosy disease in susceptible animals like BALB/C and C3H mice. Primary as well as the subcultures of strain M.EY3 grew only on the Ogawa egg-yolk medium. Colonies of this strain were creamy white and unlike other mycobacteria, produced rust-like brown spots on the medium at the sites of colonies. In vitro grown cultures M.EY3 were sensitive to isoniazid and p-nitrobenzoic acid. BALB/C and C3H mice infected with M.EY3 cultures developed lepromata similar to those produced by the in vivo grown M. lepraemurium. Both M.R56 and M.M4 scotochromogenic cultures grown in liquid Kl-1 medium are not the causative agents of murine leprosy. On the other hand, cultures M.EY3 grown on Ogawa egg-yolk medium possess characteristics similar to M.lepraemurium and are, in fact, the aetiologic agents of murine leprosy.

Animals↗
PubMed1981

In vitro cultivation of Mycobacterium lepraemurium and its identification by animal inoculation.

The primary in vitro cultures from lepromata of mice or rats previously infected with the Hawaiian strain of Mycobacterium lepraemurium were obtained on Ogawa egg-yolk medium at 34 degrees C in approximately 90 days of incubation. Optimal growth of subcultures was achieved in 40 to 60 days of incubation and such cultures were used to test their pathogenicity in animals. The in vitro grown subcultures provoked in mice subcutaneous lepromata identical to those produced by the in vitro grown M. lepraemurium. Also, mice infected subcutaneously and intravenously with the in vitro grown subcultures developed lesions in livers, spleens, and kidneys similar to those of mice infected with the mouse passage murine leprosy bacilli. Microscopically and histopathologically, the acid-fast bacilli derived from organs infected with the in vitro or in vivo grown cultures were indistinguishable from each other.

Animals↗
PubMed1981

Energy coupling mechanisms in host-grown Mycobacterium lepraemurium.

Energy coupling mechanisms of Mycobacterium lepraemurium isolated from Sprague-Dawley rats lepromata were investigated. Cell-free extracts catalyzed phosphorylation coupled to the oxidation of generated NADH, added NADH, and succinate yielding P/O ratios of approximately 0.8, 0.6, and 0.4, respectively. Ascorbate oxidation alone or in the presence of cytochrome c or N,N,N',N'-tetramethyl-p-phenylenediamine was not coupled to ATP synthesis. The oxidative phosphorylation was completely uncoupled by 2,4-dinitrophenol, 2,6-dibromophenol, pentachlorophenol, m-chlorocarbonylcyanide phenylhydrazone, dicumarol, and gramicidin at concentrations which did not cause any inhibition of oxygen uptake. While the NADH oxidation and associated phosphate esterification was markedly sensitive to rotenone and other flavoprotein inhibitors, these inhibitors had no effect, however, on the phosphorylation coupled to succinate oxidation. The respiratory chain inhibitors such as antimycin A or 2-n-heptyl-4-hydroxyquinoline-N-oxide, and cyanide were the potent inhibitors of the phosphorylation associated with the oxidation of NADH and succinate. The ATP formation coupled to the oxidation of NADH and succinate was also inhibited by oligomycin as well as by the thiol-binding agents, p-hydroxymercuribenzoate and N-ethylmaleimide. The results indicated that NADH and succinate oxidation by in vivo grown M. lepraemurium was mediated by oxidative enzymes involving first and second energy coupling sites.

Adenosine Triphosphate↗
PubMed1980

Cellulase complex of a mesophilic Streptomyces strain.

Various cellulolytic streptomycetes were isolated from natural environments. The cellulase production of one of these mesophilic Streptomyces strains, identified as S. flavogriseus was studied. When grown as a submerged culture with 1% microcrystalline cellulose (Avicel) as substrate, the strain produced considerable amounts of beta-1,4-glucan glucanohydrolase (EC 3.2.1.4; CM cellulase) in the extracellular supernatant and exhibited good overall cellulolytic activity as measured using filter paper (FP cellulase) and cotton as substrates. The maximum enzyme yields were obtained after 72 h of incubation at 30 degrees C. The optimal conditions for the FP cellulase activity were found at pH 5.6 and 40 degrees C. All beta-glucosidase and cellobiase activities were found in the mycelial fraction of the culture and could be obtained in soluble form by sonication.

Cellulase↗
PubMed1980

[Oxidative phosphorylation in Mycobacterium lepraemurium].

The generation of ATP by cell-free extracts of Mycobacterium lepraemurium isolated from Sprague-Dawley rats was investigated. Cell-free preparations catalyzed phosphorylation coupled to the oxidation of NADH and succinate yielding P/O ratios of 0.6 and 0.4, respectively. Ascorbate oxidation did not result in ATP formation. The oxidative phosphorylation was uncoupled by 2,4- dinitrophenol and pentachlorophenol. Phosphate esterification coupled to NADH oxidation was inhibited by rotenone which had no effect on ATP synthesis associated with succinate oxidation. Antimycin A and cyanide completely inhibited phosphorylation coupled to the oxidation of NADH or succinate.

Adenosine Triphosphate↗
PubMed1978

Oxidation of formate by mycobacteria of the scrofulaceum group.

Intact cells obtained from Mycobacterium scrofulaceum as well as from mycobacterial strains M.A6 and M.R56 isolated respectively from leprous tissues of armadillo and rat leproma and grown with glycerol as the oxidizable substrate catalyzed complete oxidation of formate. The stoichiometry of formate oxidase system yielded a value of 2 mol of CO2 produced per mole of O2 or per 2 moles of formate consumed. Cell-free preparations from these three strains of mycobacteria contained formate dehydrogenase which was associated exclusively in the particulate fraction. Formate oxidation was markedly stimulated by small amounts of selenite and molybdate added together. Formate-reduced minus oxidized difference spectra disclosed cytochromes of the b type while spectral evidence did not suggest the existence of cytochromes a or c components. The effect of 2-N-heptyl-4-hydroxyquinoline-N-oxide on the redox state of cytochromes indicated that formate oxidation was mediated by cytochrome b with absorption maximum of 556 nm and not of 562 nm.

Aldehyde Oxidoreductases↗
PubMed1978

Mycobacterium leprae and phenoloxidase activity.

Our earlier studies indicated that the enzyme o-diphenoloxidase was absent in Mycobacterium leprae separated from depromatous human tissues. At that time the bacilli were not available from any other source. The existence or absence of this enzyme in M. leprae recovered from infected armadillo tissues were reinvestigated. The intact cells which were metabolically active, failed to oxidize DOPA. Likewise, DOPA and its derivatives were not oxidized by the enzymatically active cell-free preparations from M. leprae. Upon incubation of DOPA for more than 2 h with whole cell suspensions or particulate fractions, there was no development of colour with an absorption maximum of 540 nm as has been reported for an intermediate of DOPA oxidation. However, DOPA and several phenolic compounds were very actively oxidized by mushroom tyrosinase. The results suggested that M. leprae is deficient in o-diphenoloxidase, and this enzyme is not an intrinsic characteristic of this mycobacterium.

Animals↗
PubMed1977

Oxidation of various substrates by host grown Mycobacteria leprae and M. lepraemurium.

Oxidation of various substrates by whole cell suspensions of M. Lepraemurium and M. leprae was investigated using manometric techniques. Yeast extract, L-cysteine, dithioerythritol, and DL-penicillamine were oxidized by both M. lepraemurium as well as by M. leprae. Although tween 80 was oxidized by M. lepraemurium cell suspensions, it was not by M. leprae. Succinate was readily oxidized by whole cells of M. leprae (without being frozen) whereas it was oxidized only by M. lepraemurium cells frozen at -40 degrees C for one minute. The results indicate that M. leprae and M. lepraemurium are capable of oxidizing some substrates without requiring any cofactor and are not dependent upon host cells for respiration.

Culture Media↗
PubMed1977

Mycobacteria from leprous tissue of an armadillo cultivated on a hyaluronic acid based medium.

Mycobacteria were isolated from pooled leprous tissues of an armadillo. The suspensions of acid fast bacilli obtained were inoculated into a culture medium composed of umbilical cord extract, supplemented with yeast extract powder and glycerol with sheep serum added. Incubation temperature was 34 degrees C. An abundant growth of mycobacteria was observed in the primo culture in four weeks. The culture was easily sub-cultured on the homologous media. The primo culture did not grow on Loëwenstein medium. The identity of the cultures of mycobacteria obtained is not yet established. The same strain of mycobacteria was cultured in media inoculated with suspensions of M. leprae decontaminated with sodium hydroxide-citrate solution. We confirm the findings of Skinsnes et al. (1975) that mycobacteria from human and animal leprous tissue can be cultured repeatedly on a hyaluronic based medium.

Animals↗
PubMed1976

The respiratory metabolism of Mycobacterium lepraemurium.

The respiratory metabolism of Mycobacterium lepraemurium isolated from Sprague-Dawley rats lepromata using several substrates was investigated. None of the intermediates of the glycolysis cycle as well as of the tricarboxylic acid cycle except succinate was oxidized by purified whole suspensions of M. lepraemurium. Likewise, many sulfur compounds such as cystine, thiourea, thioacetate, thiodiglycol, mercaptoact and some sulfhydryl compounds, e.g., cysteine, dithioerythritol, dithiorthritol, and penicillamine were readily oxidized by murine bacillary suspensions, whereas thioglycolate, thioglucose, and reduced glutathione were oxidized at a slow rate. Succinate was not or was very poorly oxidized by normal cells probably because of impermeability of the cell wall but the addition of succinate to the cell suspensions frozen for 1 min at -40 degrees C considerably enhanced oxygen uptake over the endogenous value. The oxidation of succinate was unaffected by inhibitors rotenone, atabrine, and amytal but was markedly inhibited by thenoyltrifluoroacetone, antimycin A, 2-N-heptyl-4-hydroxyquinoline-N-oxide, and cyanide. The thiol-binding agents, p-hydroxymercuribenzoate and N-ethylmaleimide were also effective inhibitors of succinate oxidation but the process was not affected by uncouplers dinitrophenol, dibromophenol, pentachlorophenol, and carbonyl-cyanide-m-chlorophenylhydrazone. The results indicated that succinate oxidation by M. lepraemurium was mediated by oxidative enzymes involving an electron transport chain with oxygen as the terminal electron acceptor.

Antimycin A↗