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Biomedical subjects

M Ishaque

Publications and source records attributed to M Ishaque.

At least 19 recordsLinked to original sources
PubMed2000

Anatomy of deer spine and its comparison to the human spine.

The anatomical parameters of the thoracic and lumbar regions of the deer spine were evaluated and compared with the existing data of the human spine. The objective was to create a database for the anatomical parameters of the deer spine, with a view to establish deer spine as a valid model for human spine biomechanical experiments in vitro. To date, the literature has supported the use of both calf and sheep spines as a suitable model for human spine experiments as the difficulty in procuring the human cadaveric spines is well appreciated. With the advent of Bovine Spongiform Encephalopathy (BSE) and its likely transmission to human in form of new variant Creutzfeld Jakob disease (CJD), there is a slight risk of transmission to humans through food chain if proper precautions for disposal of specimen are not adhered to. There is also a significant risk of transmission through direct inoculation to the researchers (Wells et al. Vet. Rec., 1998:142:103-106), working with infected bovine and sheep spine. The deer spines are readily available and there are no reported cases of deer being carriers of prion diseases (Ministry of Agriculture, Fisheries and Food, 1998). Six complete deer spines were measured to determine 22 dimensions from the vertebral bodies, endplates, disc, pedicles, spinal canal, transverse and spinous processes, articular facets. This was compared with the existing data of the human spine in the literature. The deer and human vertebrae show many similarities in the lower thoracic and upper lumbar spine, although they show substantial differences in certain dimensions. The cervical spine was markedly different in comparison. The deer spine may represent a suitable model for human experiments related to gross anatomy of the thoracic and lumbar spine. A thorough database has been provided for deciding the validity of deer spine as a model for the human spine biomechanical in vitro experiments.

Animals↗
PubMed1997

Evaluation of methods for isolation of DNA from slowly and rapidly growing mycobacteria.

Mycobacteria generally have thick cell walls and contain large amounts of lipid, making them resistant to DNA extraction. Five methods, namely, extensive enzymic digestion method (M1), 2-min mechanical glass-bead disruption method (M2), thermal shock method (M3), modified conventional enzymic digestion method (M4), and manual disruption with modified conventional enzymic digestion method (M5), were used to compare their effectiveness and simplicity in extracting DNA from slowly growing mycobacteria (Mycobacterium leprae, M. lepraemurium and M. bovis BCG), and a rapidly growing mycobacterium (M. phlei). The highest DNA yield was obtained by M2 from M. lepraemurium which produced 2.82 micrograms DNA/mg wet weight of cells, representing a theoretical yield of 78%. M3 gave the lowest DNA yield; 0.01 microgram DNA/mg wet weight of cells of M. lepraemurium was obtained. M4, in which proteinase K was used, is more effective than M1, in which subtilisin and pronase were used. M5 yielded a higher amount of DNA, but it required more manipulations to extract DNA as compared to M4. Extraction of DNA of M. leprae from nude mice is more difficult than that of M. leprae from armadillos by all of the methods used. These results suggest that the biosynthetic capabilities of these two forms of M. leprae may vary, depending on their cultural conditions and/or strain differences. Our results have shown that both M2 and M4 are the simplest, most effective and time-saving methods which are suitable for every routine laboratory to extract DNA from slowly and rapidly growing mycobacteria.

Animals↗
PubMed1996

Susceptibility of severe combined immunodeficient mice to Mycobacterium leprae.

The susceptibility of severe combined immunodeficient (SCID) mice to human leprosy bacilli was investigated. Nude mice were used as controls. SCID mice were found to be highly susceptible to Mycobacterium leprae and the progress of infection was comparatively 2-3 months earlier than observed in the nude mice. After reaching a maximum of approximately 1 x 10(9) acid fast bacilli/foot pad at about 8 months postinfection the number of bacilli gradually decreased. The progress of infection in nude mice was different from that found in SCID mice. The multiplication of M. leprae in the foot pads of nude mice continued and reached approximately 2.0 x 10(10) bacilli/foot pad and then nearly remained the same. The results indicate that SCID mice can be used as a suitable model for screening antileprosy drugs while nude mice should be involved in the production of M. leprae for use in other fields of leprosy research.

Animals↗
PubMed1994

Alpha-ketoglutarate dehydrogenase in the in vitro-grown Mycobacterium lepraemurium.

The Hawaiian and Kumato strains of Mycobacterium lepraemurium were cultivated on Ogawa egg-yolk medium, and the alpha-ketoglutarate dehydrogenase activity was investigated in cell-free preparations of this mycobacterium. The enzymatic activity was mainly localized in the particulate fraction (150,000 x g pellet), and extremely low activity was found in the soluble fraction (150,000 x g supernatant). alpha-Ketoglutarate dehydrogenase was not stable; the activity was lost completely when the enzyme was kept at 45 degrees C for 1 hr or stored at -70 degrees C. The enzyme reduced only NAD+ but not NADP+ by alpha-ketoglutarate, indicating the presence of NAD(+)-dependent alpha-ketoglutarate dehydrogenase in cultivated M. lepraemurium.

Culture Media↗
PubMed1993

Investigations into the growth of Mycobacterium leprae in a medium with palmitic acid under different gaseous environments.

Low oxygen tension has often been considered important for the growth of Mycobacterium leprae. Palmitic acid has been suggested as the oxidizable substrate for the in vitro cultivation of leprosy bacilli. The combined effects of palmitic acid and various known gas mixtures on the in vitro growth of M. leprae were investigated. When palmitic acid was included in the medium an optimal growth in both liquid and solid media was obtained between 16 to 20 weeks of incubation under gas mixtures containing 2.5 or 5% O2 and 5 or 10% CO2 as well as air. The use of different gas mixtures is tedious, time consuming and laborious. Since the cultures incubated under air gave the same cell yield as obtained when incubated under optimal gas mixtures, air alone can be used for the in vitro cultivation trials of M. leprae when palmitic acid is included in the culture medium.

Adenosine Triphosphate↗
PubMed1992

Differential cardiovascular effects of propranolol, atenolol, and pindolol measured by impedance cardiography.

We have evaluated Sramek's method of impedance cardiography as a non-invasive way of detecting the cardiovascular effects of drugs. We made cardiovascular measurements using the method during passive tilting and exercise 2 h after the oral administration of atenolol (50 and 100 mg), propranolol (40 and 80 mg), pindolol (5 and 10 mg), and placebo in seven separate studies involving eight healthy male volunteers. Equivalent doses of the pure antagonists atenolol (beta 1) and propranolol (beta 1, beta 2) produced similar reductions in heart rate, systolic blood pressure, and cardiac index, and increases in stroke volume and total peripheral resistance, particularly during exercise. In contrast the partial agonist pindolol produced increases in heart rate and cardiac index, and reductions in peripheral resistance at rest. During passive tilting and exercise pindolol reduced heart rate, but cardiac output and total peripheral resistance were unchanged except at the highest levels of exercise. The similar cardiovascular effects of atenolol and propranolol, but differing effects of pindolol, are consistent with reports using other methods of measurement. This suggests that impedance cardiography may have a place in the non-invasive assessment of the cardiovascular effects of drugs.

Adult↗
PubMed1992

Energy generation mechanisms in the in vitro-grown Mycobacterium lepraemurium.

Mycobacterium lepraemurium was cultivated on Ogawa egg-yolk medium and its energy coupling mechanisms were investigated. Cell-free extracts prepared from in vitro-grown cells catalyzed phosphorylation coupled to the oxidation of generated NADH, added NADH, and succinate-yielding ratios of phosphorus moles incorporated into high-energy bonds to oxygen atoms utilized (P/O ratios) of 0.75, 0.52, and 0.36, respectively. Ascorbate oxidation alone or in the presence of tetramethyl-p-phenyline-diamine (TMPD) did not yield any adenosine triphosphate (ATP). However, ascorbate in the presence of added cytochrome c was coupled to ATP synthesis and yielded a P/O ratio of 0.12. The oxidative phosphorylation was uncoupled by all of the uncouplers used without any inhibition of oxygen consumption. ATP generation coupled to NADH oxidation was completely inhibited by the flavoprotein inhibitors, such as rotenone and amytal; these inhibitors had no effect, however, on ATP synthesis associated with succinate oxidation. Antimycin A or 2-n-heptyl-4-hydroxy-quinoline-N-oxide (HQNO) and cyanide inhibited markedly the oxidations of NADH and succinate as well as the coupled ATP generation. The phosphorylation coupled to ascorbate plus cytochrome c was not affected by either of the flavoprotein inhibitors or by antimycin A or HQNO, but was completely inhibited by cyanide. The thiol-bearing agents p-chloromercuribenzoate (PCMB) and N-ethylmaleimide were the potent inhibitors of the phosphorylation associated with the oxidation of NADH and succinate. The results indicate that the three energy-coupling sites are functional in the respiratory chain of in vitro-grown M. lepraemurium.

Adenosine Triphosphate↗
PubMed1992

Palmitate oxidation by in vivo and in vitro grown Mycobacterium lepraemurium.

Oxidation of palmitate by Mycobacterium lepraemurium isolated from C3H mice lepromata (in vivo) and also grown on Ogawa egg-yolk medium (in vitro) was investigated. Palmitate was found to be oxidized, after a lag period of about 8 h, by both the in vivo and in vitro grown bacilli. Cell-free extracts prepared from in vivo and in vitro grown cells catalysed an active oxidation of palmitate after a lag period of 3-4 h. The amount of ATP increased, with the increase in time during oxidation of palmitate by the cell-free extracts. The generation of ATP was strongly inhibited by the inhibitors rotenone, antimycin A and cyanide as well as by the uncouplers 2,4-dinitrophenol and 2,6-dibromophenol. These results indicated that oxidation of palmitate by the in vivo and in vitro grown M. lepraemurium is mediated through the respiratory chain using oxygen as the terminal electron acceptor.

Adenosine Triphosphate↗
PubMed1990

Microbiological aspects of aerobic thermophilic treatment of swine waste.

A thermophilic strain (D2) identified as a Bacillus sp. was isolated from an aerobic digestor of swine waste after several months of operation at 55 degrees C. Aerobic thermophilic batch treatment of swine waste inoculated with strain D2 was studied in a 4-liter fixed-bed reactor. Stabilization of the waste was achieved in less than 30 h when the original chemical oxygen demand (COD) was between 15 and 20 g/liter or in less than 48 h when the COD was around 35 g/liter. When the COD was higher than 30 g/liter, the pH of the waste reached 9.2 to 9.5 during the treatment, and periodic adjustment of the pH to 8.5 was necessary to maintain the activity of the biofilm. In this reactor, ammoniacal nitrogen was completely eliminated by desorption in less than 72 h of incubation. The different packing materials used resulted in similar rates of degradation of organic matter. The thermophilic treatment was also efficient in the 75-liter digestor, and stabilization was achieved in approximately 50 h. A bank of 22 thermophilic bacterial strains originating from different environments and adapted to the thermophilic treatment of swine waste was established. This thermophilic treatment allows, in one step, rapid stabilization of the waste, elimination of the bad smell, and complete elimination of ammonia nitrogen by stripping.

Aerobiosis↗
PubMed1990

Nitrification of swine waste.

Complete oxidation of ammonia nitrogen (approximately 1000 mg/L) to nitrite was observed in stabilized swine waste after 49 days in incubation at 400 rpm and 29 degrees C, only if 10% (v/v) activated sludge from a wastewater treatment unit and 1.5% (w/v) CaCO3, were added. Stabilized swine waste contains less than 0.09 most probable number (MPN) per millilitre of nitrosobacteria and 2.3 MPN/mL of nitrobacteria. In activated sludge, the concentrations of these bacteria were 2.4 MPN/mL for nitrosobacteria and 4.2 x 10(5) MPN/mL for nitrobacteria. In the swine waste where ammonia was oxidized to nitrite, the nitrosobacteria growth increased to 5.5 x 10(5) MPN/mL, while the nitrobacteria growth decreased to 2.3 MPN/mL. Inoculation of a freshly stabilized swine waste with 10% (v/v) of the active nitrifying waste and addition of 1.5% (w/v) CaCO3, accelerated the oxidation of ammonia nitrogen to nitrite; the reaction was completed after only 5 days of incubation. Increasing the incubation period to 10 days resulted in the complete oxidation of the accumulated nitrite to nitrate. In the stabilized swine waste, complete nitrification without accumulation of nitrite was obtained in only 5 days of incubation when the waste was inoculated with both enriched nitrifying populations (10(6)-10(7) MPN/mL).

Animals↗
PubMed1990

Growth of Mycobacterium leprae under low oxygen tension.

Despite numerous attempts, Mycobacterium leprae has yet to be cultivated in vitro. This organism has been considered as microaerophilic. The effects of various known gas mixtures on the in vitro growth of M. leprae were investigated. A gas mixture containing 2.5% O2 and 10% CO2 was found to be more favourable for the growth of this mycobacterium on artificial medium. Growth was evaluated by three parameters namely cell counts, bacterial ATP and DNA. An optimal growth of M. leprae, as determined by all three parameters, on both liquid and solid media was obtained between 18 and 24 weeks of incubation under optimal gas mixture. Solid medium which contained egg-yolk was relatively more beneficial for in vitro growth than the liquid medium. The cultivated bacilli exhibited some important characteristics specific for M. leprae, including growth in mouse foot-pads. The bacilli gradually lost their power of adaptation to grow on artificial media and did not show any ATP or DNA after about 36 weeks of incubation.

Adenosine Triphosphate↗