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Biomedical subjects

G H Lang

Publications and source records attributed to G H Lang.

10 recordsLinked to original sources

Increased technetium uptake is not equivalent to muscle necrosis: scintigraphic, morphological and intramuscular pressure analyses of sore muscles after exercise.

A scintigraphic technique employing technetium pyrophosphate uptake was used to identify the area of skeletal muscle damage in the lower leg of four runners 24 h after an ultramarathon footrace (160 km). Most of the race had been run downhill which incorporated an extensive amount of eccentric work. Soreness was diffuse throughout the posterior region of the lower leg. In order to interpret what increased technetium uptake reflects and to express extreme endurance related damages, a biopsy was taken from the 3-D position of abnormal uptake. In addition, intramuscular pressures were determined in the deep posterior compartment. Scintigraphs revealed increased technetium pyrophosphate uptake in the medial portion of the gastrocnemius muscle. For 3698 fibres analysed, 33 fibres (1%) were necrotic, while a few other fibres were either atrophic or irregular shaped. A cluster of necrotic fibres occurred at the fascicular periphery for one subject and fibre type grouping occurred for another. Ultrastructural analysis revealed Z-line streaming near many capillaries and variously altered subsarcolemmal mitochondria including some with paracrystalline inclusions. The majority of the capillaries included thickened and irregular shaped endothelial cells. Intramuscular pressures of the deep posterior compartment were slightly elevated (12-15 mmHg) for three of the four subjects. Increased technetium uptake following extreme endurance running does not just reflect muscle necrosis but also subtle fibre abnormalities. Collectively, these pathological findings are attributed to relative ischaemia occurring during the race and during pre-race training, whereas, intramuscular pressure elevations associated with muscle soreness are attributed to mechanical stress caused by extensive eccentric work during the race.

Adult↗

Q fever: an emerging public health concern in Canada.

Q fever in humans and coxiellosis in livestock are on the increase in Canada. The progressive spread of Coxiella burnetii takes place in the animal reservoirs of the rickettsia, mainly domestic ruminants. Human Q fever is a reverberation of the coxiellosis situation on our farms. Increasing animal concentration resulting from the industrialization of agriculture and oversight of the infection in livestock permitted the extension of the zoonotic problem on the farms. Initiative for control of coxiellosis, however, is called for by public health interests at the present time to assure occupational health and safety for workers, and the protection of the general population residing in coxiella threatened environments.

Animals↗

Q fever.

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Animals↗

Serosurvey of Coxiella burnetii infection in dairy goat herds in Ontario. A comparison of two methods of enzyme-linked immunosorbent assay.

Two technical variations of enzyme-linked immunosorbent assay for the detection of antibodies to Coxiella burnetii were compared in this serosurvey on 20 Ontario dairy goat herds. Both a trichloracetic acid extract and a coctoantigen of purified coxiellas were used to sensitize the microtitration plates. Technical differences related to coating pH, serum dilutions tested and interpretation of results. Results agreed in 98.6% of sera examined, the differing sera were in the low titer borderline range. Only 20% of the herds had seroreactors.

Animals↗

Hyponatremia and ultramarathon running.

Two ultramarathon runners were hospitalized with hyponatremic encephalopathy after completing 80 and 100 km (50 and 62 miles), respectively, of the 1983 American Medical Joggers Association ultramarathon race in Chicago. The two runners consumed such large quantities of free water during the race that apparent water intoxication developed. Both recovered satisfactorily after treatment with intravenous saline. The hyponatremia was caused primarily by increased intake and retention of dilute fluids and contributed to by excessive sweat sodium loss. A possible explanation for the postrace onset of symptoms might be the sudden absorption of fluid in the gastrointestinal tract after exercise ceased, with subsequent further dilution of the plasma sodium. Hyponatremia, which has not been commonly associated with exercise, should be considered as a possible consequence of ultraendurance events.

Adult↗

Prevalence of reovirus 1, 2 and 3 antibodies in Ontario racehorses.

The sera of 2596 thoroughbred and standardbred racehorses from Ontario were examined by hemagglutination-inhibition for antibodies to reovirus types 1, 2 and 3. The prevalence of antibodies differed between the standardbred and thoroughbred horses and varied with the age groups within the two populations. While reovirus 1 was the principal virus type infecting thoroughbreds, all three types seemed to infect standardbred horses. Differences of these findings with data from similar studies in Europe are mentioned and the epizootiological and pathological significance of these findings are discussed.

Animals↗

Bioconjugation of ribonuclease A: a detailed chromatographic and mass spectrometric analysis of chemical modification by a cross-linking reagent.

The modification of ribonuclease A with the heterobifunctional cross-linker, 4-succinimdyloxycarbonyl-methyl-alpha-[2-pyridyldithio]-toluene (SMPT) is described. RNase A has 11 potential sites of modification by the SMPT reagent. Tracking the two-dimensional separation and proteolytic digestion of SMPT-modified RNase A with ESI/FTICR-MS and HPLC/ESI/QIT-MS demonstrates the detailed information about number of SMPT modifications and sites of modification that can be obtained by application of these techniques. Analysis of native and modified RNase A tryptic digests by ESI/FTICR-MS resulted in the identification of the sites of modification. Semiquantitative results of the reactivity of certain lysine residues toward the coupling reagent SMPT are presented. Two sites (lysines 1 and 37) are highly reactive, while three sites (lysines 41, 61, and 104) appear to be unreactive toward SMPT under the conditions used. Experimental results demonstrate that quantitative comparison of relative intensities of peptide sequences of different charge states is not possible. No correlation was found between number of basic residues and sensitivity to detection. Digestion of the modified and unmodified RNase A by subtilisin followed by examination by HPLC/ESI/QIT-MS and MS(n) enabled further investigation of modification on lysines 1 and 7, including modification at the epsilon- and alpha-amino positions on lysine 1.

Amino Acid Sequence↗