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Biomedical subjects

M Ahmad

Publications and source records attributed to M Ahmad.

At least 325 records · Page 18Linked to original sources
PubMed1989

Effect of the timing of tourniquet release on postoperative hematoma formation: an experimental animal study.

There is a controversy over when to release a pneumatic tourniquet after completing a hand surgical procedure. To study this controversy, we performed a standardized operation with tourniquet inflow occlusion on both lower legs of a series of rabbits. Total tourniquet time and the procedure performed, including intraoperative Bovie electrocautery of actual and potential bleeding points identified with 2.5 X loupe magnification, were identical on the two sides, except for the method of tourniquet release. On one leg, the tourniquet was released and all new bleeding points were controlled prior to wound closure. On the other leg, the tourniquet was released after the wound had been closed and dressed. Animals were injected with technetium-99m-labeled red blood cells and scanned to measure hematoma formation. Qualitatively, we observed more label in the leg whose tourniquet was released after wound closure in 17 of the 20 animals (p less than 0.005). Quantitatively, we also measured more mean label in the leg whose tourniquet was released after the wound was closed (p less than 0.001). Tourniquet release after wound closure was associated with greater hematoma formation.

Animals↗
PubMed1989

An analysis of breakage of ultrasonic files during root canal instrumentation.

The incidence of fracture of Cavi-Endo ultrasonic K-files during ultrasonic root canal preparation was evaluated. In addition, the appearance and the sites of fractures were examined in relation to the nodal points on the file. The displacement amplitudes and the hardness of the files were quantified to determine their relationship to fracture. It was observed that the files exhibited a low incidence of fracture, which was of the brittle type and occurred at the apical ends. The displacement amplitude and the hardness of the files did not appear to influence the incidence of fracture.

Equipment Failure↗
PubMed1989

Effect of ultrasonic instrumentation on Bacteroides intermedius.

Two physical mechanisms of ultrasound, cavitation and acoustic streaming, were investigated in an ultrasonic endodontic unit. In addition, the potential of ultrasonic instrumentation for disruption of Bacteroides intermedius was examined at various time intervals. The ultrasonic file could not generate cavitation within the recommended power settings indicated for endodontic purposes. However, there was evidence of acoustic streaming. The latter phenomenon resulted in destruction of 21.6%, 30.4% and 92.9% of test bacteria after 1, 5 and 15 min sonication respectively. It appears that ultrasonic instrumentation of root canals has little bactericidal effect.

Bacteroides Infections↗
PubMed1989

The effect of gitalin in the sodium pump in erythrocytes of Rattus norvegicus.

The study reports of the effect of gitalin on the erythrocytes sodium pump of Rattus norvegicus the administration of 0.75 mg gitalin daily for seven days increased the average sodium content in erythrocytes. The rise in erythrocyte sodium content following acute gitalin therapy was proportionally more than the number of sodium pumps occupied by gitalin.

Journal Article↗
PubMed1989

Acute sporadic hepatitis non A non B clinical features and biochemical profile.

Hepatitis Non A Non B is the commonest type of sporadic hepatitis in Pakistan. To document its clinicopathological pattern, one hundred consecutive cases were studied. The clinical presentation indicates that it is a disease of mild severity presenting with anorexia and dark coloured urine. The rise in serum bilirubin transaminases and alkaline phosphatase is moderate. Monophasic pattern of transaminase elevation is seen. Chronic sequelae do not occur. The disease shows certain differences from western countries and Japan. It resembles hepatitis A. The possibility that it is caused by a closely related virus may have to be considered.

Acute Disease↗
PubMed1989

Thallium 201 uptake in kidneys and heart as an indicator of prognosis in septic shock in the rat.

The change in distribution of cardiac output in septic shock was examined by radionuclide imaging with thallium 201 thallous chloride (201Tl) which allows noninvasive evaluation of relative blood flow to various organs except for the brain. Pseudomonas aeruginosa (1 X 10(9)-2 X 10(10) organisms) were inoculated into the thigh of rats 18-24 hr before the study. The mean arterial pressure was measured with an intracarotid catheter. Fractional blood flow to the heart, kidneys, and liver was evaluated as organ uptake of 201Tl. Those with zero or less than 5% kidney uptake (n = 8) had a high heart uptake and all died within 3 hr even if their pressure was maintained. In contrast, 20 out of 24 rats with kidney uptake greater than 5% survived for more than 6 hr. Those results suggest that the kidney uptake, representing fractional renal blood flow, is an excellent indicator of short-term prognosis in septic shock.

Animals↗
PubMed1989

Radionuclide imaging of experimental atherosclerosis with nonspecific polyclonal immunoglobulin G.

The utility of nonspecific polyclonal IgG for external imaging of experimental atherosclerosis was tested in a series of rabbits after balloon catheter deendothelialization of the abdominal aorta. Following injection of 111In-IgG, 111In-Fc, or 111In-Fab serial images were recorded. In addition, several animals received 125I-low density lipoproteins [125I-LDL], or 125I human serum albumin [125I-HSA] as positive and negative controls. Forty-eight hours after injection of the radiolabeled proteins, the aortas were removed, divided into abdominal and thoracic regions, counted, and autoradiographed. The images acquired after injection of 111In-IgG and 111In-Fc, showed clear focal accumulation of radioactivity in the healing abdominal aorta. In contrast, the images obtained after injection of 111In-Fab did not show focal radionuclide accumulation. For 111In-IgG and 111In-Fc there were three to six times as many counts in the abdominal as in the thoracic aorta, while for 111In-Fab and 125I HSA, the abdominal and thoracic counts were nearly equal. The results suggest that radiolabeled IgG and Fc can be used to image experimental atherosclerosis.

Animals↗
PubMed1988

Induction of in vitro tumoricidal activity in alveolar macrophages and monocytes from patients with lung cancer.

Human alveolar macrophages (AMs) and blood monocytes were obtained from 65 smoking and nonsmoking normal volunteers and 29 patients with lung cancer. The oxidative metabolic response of these cells was measured by superoxide anion production after incubation with lipopolysaccharide. In addition, tumoricidal activity of AMs and monocytes was assessed against [3H]thymidine-labeled tumor target cells. Smoking was associated with depressed AM superoxide anion responses in normals but not in patients. In contrast, smoking appeared to slightly elevate monocyte superoxide anion activity. AMs and monocytes exposed to lipopolysaccharide or recombinant gamma-interferon showed tumoricidal activity in all groups. Mean cytotoxicity values of smoking patients versus smoking normals and exsmoking patients versus nonsmoking normals were not significantly different. Smoking, however, in both patients and normals was associated with significantly (P less than 0.005) depressed AM cytotoxicity levels (less than 40%) compared to nonsmoking volunteers and exsmoking patients. Activated AMs from cancer patients and normals were cytotoxic against three different tumorigenic cell lines but not against a nontumorigenic line. No correlation between monocyte and AM cytotoxic activity within single individuals was found. We conclude that AM and monocytes from smoking and exsmoking patients can be activated after exposure to immunomodulators; however, smoking may be slightly suppressive to cytotoxic responses. These studies provide a rationale for clinical trials of immunomodulators in patients with lung cancer.

Adult↗
PubMed1988

Post mortem studies on infertile buffalo bulls: testicular histology.

Testicular tissues of 22 buffalo bulls (Bubalus bubalis) which suffered from three types of infertility were examined histologically. Nine bulls with no sexual libido showed underdeveloped seminiferous tubules; five of them also had various forms of germinal tissue hypoplasia (bilaterally complete, partial or incomplete) and in the other four the seminiferous tubules showed developed layers of germinal epithelium but no complete spermiogenesis. Among 11 bulls which had always produced poor quality semen one suffered from incomplete bilateral testicular hypoplasia and two had simple testicular degeneration; five showed marked testicular degeneration associated with fibrosis of intertubular spaces, and in three there was intertubular fibrosis and tubular stasis. In two bulls in which the quality of semen had deteriorated one showed bilateral partial testicular hypoplasia and the other had bilateral testicular degeneration with unilateral intertubular fibrosis and tubular stasis.

Animals↗
PubMed1988

Peripheral small cell undifferentiated carcinoma of the lung. Clinicopathologic features of 17 cases.

Seventeen cases of resectable peripheral small cell undifferentiated carcinoma of the lung were studied (average size, 2.1 cm; range, 0.9-3.5 cm). The carcinomas exhibited predominantly mixed intermediate and fusiform/spindle subtypes; in seven carcinomas there were at least some foci of oat cell subtype. There was no histologic evidence of typical carcinoid tumor. Seven cases were fixed in solutions appropriate for immunohistologic study; these exhibited prominent neuron-specific enolase activity but less prominent and more variable staining for the carcinoembryonic antigen and cytokeratins. All 17 cases were deemed resectable and had no clinical or radiologic evidence of metastasis. Seven (41%) patients died with recurrent and/or metastatic carcinoma (average survival, 1.7 years); five of these patients had carcinomas with at least some foci of oat cell foci subtype.

Adult↗
PubMed1988

Human alveolar macrophage function: differences between smokers and nonsmokers.

Human alveolar macrophages and peripheral blood monocytes were obtained from smoking and nonsmoking normal volunteers. The macrophages and monocytes were incubated in vitro with bacterial lipopolysaccharide (LPS). The oxidative metabolic response of these cells was measured by superoxide anion production. Macrophages from smokers were suppressed in their superoxide anion response to LPS activation as compared to macrophages from nonsmokers. Monocytes from smokers and nonsmokers were not different. The cytotoxic properties of these macrophages and monocytes were assessed by an in vitro 3H-thymidine release assay against various allogeneic target cells. Macrophages and monocytes exposed to LPS were rendered tumoricidal. Macrophages from nonsmokers appeared to generate greater cytotoxic activity than macrophages from smokers. Macrophages from both smokers and nonsmokers were cytotoxic for three different tumorigenic cell lines but not for a nontumorigenic cell line. Monocytes from smokers and nonsmokers were not different in cytotoxic activity. We conclude that macrophages from both smokers and nonsmokers can be activated after exposure to LPS; however, macrophages from smokers may be slightly suppressed in their responses.

Adult↗
PubMed1988

Effect of alkylated and intercalated DNA on the generation of superoxide anion by riboflavin.

Superoxide anion (O2.-) was photogenerated upon illumination of riboflavin in fluorescent light. The rate of O2.- formation was stimulated by double stranded DNA but not by denatured DNA or RNA. Depurinated DNA, which was predominantly depleted in guanine residues, did not exhibit the stimulatory effect, indicating an interaction of riboflavin, or active oxygen species derived from it, with guanine bases. Also, the stimulation of O2.- photogeneration was not observed with ethidium bromide but was seen with proflavin-intercalated DNA. Since ethidium bromide intercalates preferentially between purines and pyrimidines, and proflavin prefers dA-dT rich sites, these results were interpreted to suggest that the interaction of riboflavin with DNA is mainly with GC or CG base pairs.

Animals↗
PubMed1988

pH induced damage and repair in E. coli.

Escherichia coli lost its colony-forming ability when suspended in Tris/NaOH or Tris/Mg2+ buffers of pH 10.0 and 4.0, respectively. A significant decrease in the survival of radiation-sensitive mutants recA, polA, res, rer and lexA was observed as compared to their wild-type counterpart under these conditions. The alkali-injured cells were found to recover when incubated at 37 degrees C for 2 h in 0.05 M phosphate buffer of pH 8.0, whereas no such liquid holding recovery was observed in recA and lexA mutants. Recovery in phosphate buffer was not affected by metabolic inhibitors. As a result of alkali treatment, the sensitivity of bacteria to ultraviolet light (UV) was enhanced. However, on incubation for 2 h in recovery buffer at 37 degrees C, the bacteria regained partial UV resistance. Bacteria exposed to alkaline environment exhibited an enhanced level of mutagenesis. Contrary to the treated wild-type, the mutants recA and lexA did not exhibit any increase in the mutation frequency. Alkali treatment to GC----AT transition mutants of Salmonella typhimurium, TA102 and TA104 resulted in the highest number of revertants per plate.

DNA Damage↗
PubMed1988

Topology of membrane insertion in vitro and plasma membrane assembly in vivo of the yeast arginine permease.

We have examined the topology of the yeast arginine permease, a plasma-membrane protein with multiple membrane-spanning domains. Using fusions of the permease with the glycosylatable secreted yeast protein, acid phosphatase, we identified membrane-spanning sequences that can translocate adjacent acid phosphatase across the membrane of the endoplasmic reticulum (ER), as measured by in vitro glycosylation. Examination for the presence or absence of glycosylation in a systematic series of such fusions gave an internally consistent model for the lumenal or cytoplasmic disposition of the acid phosphatase reporter, defining the topology of the permease. The phenotypes of a further set of arginine permease gene fusions with portions of the gene for the secreted protein, killer toxin, suggest that the pathways of export of membrane and secreted proteins need not be functionally distinct.

Acid Phosphatase↗