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Biomedical subjects

R A Khan

Publications and source records attributed to R A Khan.

At least 91 records · Page 5Linked to original sources
PubMed1985

Peripheral nerves in Fisher's syndrome.

A case is presented of a 33-year-old male with ophthalmoplegia, ataxia and areflexia followed by complete recovery. There was no clinical evidence of motor weakness or sensory disturbances in the limbs. Electromyography and nerve conduction studies were normal. Sural nerve biopsy during the sixth week of illness revealed no abnormalities.

Adult↗
PubMed1983

Long term exposure of marine fish to crude petroleum-I. Studies on liver lipids and fatty acids in cod (Gadus morhua) and winter flounder (Pseudopleuronectes americanus).

1. Total lipids, total phospholipids, lipid class and fatty acids have been studied in the livers of cod and winter flounder from the Northwest Atlantic following long-term exposure to crude petroleum. 2. The levels of free fatty acids and total phospholipids were elevated and triglycerides depleted significantly in the males and females of both species in the experimental groups. 3. The essential fatty acids of C20.5, C22.5 and C22.6 series were significantly altered in the oil-exposed animals. 4. These findings indicate that marine fish, following long-term exposure to crude petroleum, tend to (a) use up their stored energy of neutral lipids and (b) develop changes in membrane structure and function.

Animals↗
PubMed1983

Effects of 3,4-diaminopyridine on mechanical and electrical responses of frog single muscle fibres.

The effects of 3,4-diaminopyridine (3,4-DAP) were studied on isolated muscle fibres of the frog in concentrations ranging between 0.025 and 5.0 mM. Isometric twitch and tetanus responses were recorded at temperatures between 2.5 and 3.9 degrees. 3,4-DAP caused a concentration-dependent increase in twitch amplitude, maximum effects being obtained at a concentration of 3 mM with a mean increase in tension of 70 +/- 12% of control (n = 7). 3,4-DAP in 3 mM concentration had only a slight increase in initial rate of rise of twitch tension (mean increase 8 +/- 4%) but increased the time to half peak tension by 59 +/- 9% and the time from peak tension to half relaxation by 78 +/- 10%. No significant effect of 3,4-DAP was observed on the initial rate of rise and total amplitude of the isometric tetanus. The twitch potentiating effect of 3,4-DAP developed gradually with the number of times the fibre was stimulated and reached a maximum level after 40-50 stimulations. A gradual increase in the duration of the action potential was also observed. It is suggested that 3,4-DAP, like 4-aminopyridine, potentiates the twitch by means of prolonging the duration of the action potential.

4-Aminopyridine↗
PubMed1983

Effects of crude oils on the gastrointestinal parasites of two species of marine fish.

To assess the effect of crude oil on selected gastrointestinal parasites of fish, winter flounder (Pseudopleuronectes americanus) naturally infected with a digenetic trematode (Steringophorus furciger), were exposed to contaminated sediment or water soluble fractions of Venezuelan crude oil for 34 and 160 days respectively. Similarly, Atlantic cod (Gadus morhua) harboring an acanthocephalan (Echinorhynchus gadi), were treated with extracts of Hibernia and Venezuelan oils for periods of 81 to 140 days. In all cases prevalence and intensity of parasitic infections were lower in oil-treated fish. The effect appeared to be more pronounced within fish exposed to water soluble extracts than to oil-contaminated sediment. Fewer parasites present in fish exposed to oil might be attributed to direct toxicity induced by drinking water soluble fractions of crude oil and/or modification of the gut environment brought about by changes in host physiology.

Acanthocephala↗
PubMed1981

Mortality in captive Atlantic cod, Gadus morhua, associated with fin rot disease.

A total of 320 of 621 (52%) captive Atlantic cod, Gadus morhua, died from fin rot over an 8-year period; mortality reached high proportions in 1979 when 110 of 168 (66%) succumbed. Lesions were confined to the fins, skin and dermal musculature and were observed 3-10 days after the fish were placed in laboratory aquaria. Erosion of the fins and caudal peduncle, accompanied by petechiae and ulceration also were apparent in the trunk region. Most deaths occurred within 2 months after capture. Infection was associated with depressed hematocrit, hemoglobin and total plasma protein and an increase in circulating immature erythrocytes and neutrophils. Mortality was probably due to physiological stress resulting from excessive blood loss. Three genera of bacteria, mostly Pseudomonas, but also Aeromonas and Vibrio, were isolated from fin rot tissues and possibly are the causative agents of the disease.

Animals↗
PubMed1981

Factors affecting the labeling efficiency and stability of technetium-99m-labeled glucoheptonate.

Factors influencing the labeling efficiency and in vitro stability of 99mTc-labeled glucoheptonate (Tc-GH) were investigated. Using commercially available glucoheptonate kits (New England Nuclear), the following factors were studied: (1) amount of activity added to each kit vial, (2) different brands of 0.9% sodium chloride injection, (3) evaluation of eluates from three commercially available generators, (4) different chromatography systems, (5) storage of the preparation at room temperature and under refrigeration, and (6) labeling with eluates obtained at various times (6, 24, 48, 72, and 96 hours) since previous elution of the generator. Results showed that Tc-GH prepared using 100 mCi of sodium pertechnetate from a Mallinckrodt generator, low-dissolved-oxygen 0.9% sodium chloride injection to make up a constant 5-ml volume, and chromatography with methyl ethyl ketone/sodium chloride on an ITLC-SG system gave the best labeling efficiency over a 24-hour period. Storage temperature and time since previous elution had no effect on labeling efficiency or stability.

Drug Stability↗
PubMed1980

99mTc-MDP extraction in relation to 81mKr perfusion following a partial osteotomy in the dog tibia.

The bone mineral extraction of technetium-99m-methylene diphosphonate (99mTc-MDP), and blood supply of Krypton-81m (81mKr) have been compared in normal and osteotomy regions of the canine tibia. A partial osteotomy was carried out under aseptic conditions, and isotopic measurements made over a period of 123 days. Both blood flow and bone mineral extraction increase after a partial osteotomy.

Animals↗
PubMed1980

Effect of sample preparation on cerebrospinal fluid protein patterns in polyacrylamide gels.

The method of preparing CSF and dilute serum samples for polyacrylamide gel electrophoresis has a marked effect on the pattern of the resolved proteins. The incorporation of sucrose or glycerol into the sample seriously impairs the quality of the resolution and affects the actual number of bands resolved and the relative mobility of certain proteins. The use of sucrose as an anti-convection medium in dense samples such as serum and CSF is not recommended.

Blood Protein Electrophoresis↗
PubMed1980

Trypanosoma murmanensis: its effects on the longhorn sculpin, Myoxocephalus octodecemspinosus.

A study was undertaken to ascertain the effects of Trypanosoma murmanensis, on adult longhorn sculpins (Myoxocephalus octodecemspinosus) following experimental infection. Blood samples, taken at intervals after infection, indicated a decrease in hematocrit, hemoglobin and total plasma protein levels which did not return to normal for at least 72 days. An increase of lymphocytic cells occurred about 42 and 58 days but reverted later to normal levels. Anemia persisted despite low parasitemias and might be attributed to lytic factors released directly or indirectly by the parasite and/or an inability of the erythropoietic system to respond following the initial blood loss.

Anemia↗
PubMed1980

A haemogregarine from the American alligator (Alligator mississippiensis).

Haemogregarina crocodilinorum Börner 1901 is redescribed from the blood of the American Alligator (Alligator mississippiensis). Gametocytes occurred in erythrocytes and erythrocytic schizonts contained about eight merozoites (range, 6--12). Gametogony and sporogony occurred in the gut of the leech, Placobdella multilineata and intracellular, unisporocystic oocysts were found within epithelial cells of the leech's intestinal wall. Presumed sporozoites were present in the intestinal contents. Attempts to transmit the parasite via leeches failed. The haemogregarine was widely distributed in southern United States and was found in 77 (59%) of 130 alligators examined. A comparison of this parasite is made with other haemogregarines reported from crocodilian reptiles.

Alligators and Crocodiles↗
PubMed1979

A rabbit model to study the biokinetics of radiopharmaceuticals in bone.

A technique is described using the rabbit as the 'animal model' to measure the rate of extraction of the bone-seeking agent, technetium labelled ethane-1-hydroxy-1, 1-diphosphonate (99Tcm-EHDP) following constant-rate infusion into the femoral nutrient artery. The extraction is shown to be approximately linear for a period of 60 min. Washout of the tracer from bone was followed for a further 60 min period and graphical analysis shows that each curve could be resolved into two distinct exponential functions. The 2-h residue of 99Tcm-EHDP in bone has been examined and is found to be dependent upon its route of administration. A high residue (43.7 +/- 5.1%) results when the infusate is delivered directly into the nutrient artery and the single muscular branch is tied off. Retrograde infusion via the femoral artery results in a lower residue (7.8 +/- 2.3%). The close correlation of these results in the rabbit with our previous findings in the dog suggested that the rabbit model described can be used to study the kinetics of other radiopharmaceuticals during their passage through bone.

Animals↗
PubMed1979

Autoradiography of technetium-labelled diphosphonate in rat bone.

The passage of technetium-labelled methylene diphosphonate (99mTc-MDP) across rat bone was examined by autoradiography. The autoradiographs showed that shortly after an injection of the bone-seeking agent there was activity outside the bone, within the bone marrow and also adjacent to the highly vascular epiphysial plate; the distribution of the isotope in the incubated bone appeared to be non-uniform, a high concentration being seen adjacent to the epiphysial plate and also on the surfaces of the bone. The evidence suggested that a two-fold mechanism resulted in the uneven distribution of 99mTc-MDP. The first factor probably represented the regional distribution of blood flow with a transcapillary movement of the tracer from the capillary bed to the extravascular space; the subsequent incorporation of the tracer into bone appeared to depend on the nature of the bone matrix.

Animals↗