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Biomedical subjects

C M Williams

Publications and source records attributed to C M Williams.

At least 199 records · Page 11Linked to original sources
PubMed1979

Identification and quantitative determination of o- and m-hydroxymandelic acid in human urine.

o-Hydroxymandelic acid and m-hydroxymandelic acid have been identified in human urine by gas chromatography mass spectrometry selected ion monitoring. After solvent extraction the urinary acids were converted to their O-trifluoroacetoxy methyl ester derivatives which were identified by comparison of the retention times and relative intensities of the characteristic m/z 374 and m/z 315 ions with those from authentic samples. 4,6-[2H3]-o-hydroxymandelic acid and 2,4,6-[2H3]-m-hydroxymandelic acid were synthesized for use as internal standards in the quantitative estimation of the isomeric hydroxymandelic acids excreted in urine. In ten normal adults the following results were obtained: o-hydroxymandelic acid 4--16 ng mg-1 creatinine and m-hydroxymandelic acid 11--71 ng mg-1 creatinine. Acid hydrolysis of the urine or ingestion of a diet of known composition did not affect these results, indicating that these compounds are excreted as the free acids and probably arise by metabolism of the corresponding phenylethanolamine(s).

Diet↗
PubMed1979

Echocardiographic recognition of atrioventricular valve stenosis associated with endocardial cushion defect: pathologic and surgical correlates.

The association of either mitral or tricuspid stenosis with endocardial cushion defects has been well recognized pathologically but is infrequenctly diagnosed clinically. M mode echocardiographic features such as markedly disproportionate ventricular size, abnormal mitral or tricuspid diastolic echoes or failure to define adequately an atrioventricular (A-V) valve are strongly suggestive of associated stenosis of that valve. In this study mitral stenosis in association with endocardial cushion defect was correctly diagnosed in four of five patients. In the fifth patient (the first seen) the condition was easily diagnosed retrospectively. Tricuspid stenosis was similarly diagnosed prospectively in three of four patients. Significant stenosis was not overlooked or misdiagnosed in any patient with an endocardial cushion defect. Significant stenosis of an A-V valve in association with endocardial cushion defect carries a high mortality. It is important to recognize the combined lesion clinically because infants with it are not suitable for total surgical correction. Palliative surgical procedures with aggressive medical therapy probably offer the infant the best chance of surviving until ventricular growth may render corrective surgery feasible.

Aorta↗
PubMed1979

Adrenergic activity of ortho-, meta-, and para-octopamine.

DL-o-, and p-octopamine were tested for beta- and alpha-adrenergic activity in rats. When compared to DL-isoproterenol, a beta-adrenergic agonist, all three isomers failed to show significant beta-adrenergic activity as assessed by intiation of thirst and by increase in tail skin temperature. All three isomers increased mean blood pressure in pentolinium-blocked rats. Of the three isomers, m-octopamine possessed the greatest alpha-adrenergic activity. When the responses were compared with those induced by L-norepinephrine, the order of activities was: 1:0.01 :0.0005 :0.0007 for norepinephrine, m-, p- and o-octopamine, respectively. Thus, DL-m-octopamine has about 1/100th the alpha-adrenergic activity of L-norepinephrine.

Adrenergic alpha-Agonists↗
PubMed1979

A computerized rotating laminar radionuclide camera.

We have constructed a radionuclide camera that embodies a unique detector-collimator concept and provides a radically new approach to imaging. The heart of the instrument is a linear array of semiconductor detectors separated by thin tungsten plates that confine the field of view of each detector to one dimension. This collimator design has a higher collection efficiency than the standard parallel-hole collimator but cannot directly produce a two-dimensional image. When multiple measurements are taken as the array rotates through 180 degrees, a computerized image restoration algorithm can then produce two-dimensional images with resolution determined by the width of the detectors. A small prototype camera has produced images with resolution superior to conventional Anger cameras.

Computers↗
PubMed1978

Echocardiography in adriamycin cardiotoxicity.

Twenty-six patients receiving adriamycin for osteogenic sarcoma had serial echocardiographic assessments of their left ventricular function. A statistically significant deterioration of function was noted throughout the course. Ventricular function tended to normalize in the period following cessation of adriamycin. The velocity of circumferential fibre shortening (Vcf) and ejection fraction (EF) were the best parameters. Sudden declines in these values resulted in us withholding therapy until the parameters again improved. Fatal congestive heart failure was seen in only one patient. Echocardiography thus provides the clinician with a valuable tool enabling one to improve the therapeutic usefulness of adriamycin by removing much of the uncertainty over the development of cardiotoxicity.

Adolescent↗
PubMed1978

Aortic stenosis in children. Experience with echocardiographic prediction of severity.

Fifty-six children with aortic stenosis were investigated both by echocardiography and cardiac catheterization. The ratio of end-systolic wall thickness (Ws) to internal diameter (LVES) across the minor axis of the LV as determined by echocardiography and multiplied by a factor of 245 predicts left ventricular pressure (r = 0.83). Subtracting the arm systolic blood pressure from the predicted intraventricular systolic pressure (PISP) gives a predicted systolic pressure gradient (r = 0.91). The technique is found to be useful for both initial and sequential noninvasive assessment of aortic stenosis with normal LV function irrespective of the level of obstruction. It is shown to apply equally well to wide range of LV pressures, is independent of volume load, and is useful in predicting small gradients. Some common problems encountered with the measurements are examined in detail.

Adolescent↗
PubMed1978

The reliability and practicality of single crystal echocardiography in the evaluation of single ventricle. Angiographic and pathological correlates.

A prospective clinical and echocardiographic diagnosis of single ventricle was made in 42 patients. Each was evaluated for the number of atrioventricular (A/V) valves, presence of an outflow chamber (OC), A/V valve-semilunar continuity, and orientation of the great arteries. Angiographic correlations were subsequently obtained in 40 and autopsies in 12. The overall diagnosis of single ventricle was substantiated in 39. Two other patients diagnosed as single ventricle by angiography were thought to have large ventricular septal defects on echocardiography. Tricuspid valve was interpreted as septum in one. The angiographic diagnosis of single ventricle was incorrect in another, correctly diagnosed by echocardiography and confirmed at pathology. The differential diagnosis also included A-V canal, L-transposition of the great arteries, double outlet right ventricle, and tricuspid atresia. This last condition has to be differentiated on clinical evidence. The echocardiograms were of particular value in determining the number of A/V valves. Two great arteries were demonstrated in 74% of patients and their relationship was correctly determined in 79% of these. Both imaging techniques agreed closely as to A/V valve-semilunar continuity and presence of an OC, but both showed some inaccuracies compared to pathological specimens. The echocardiogram helps both in planning catheterization and in evaluating the overall diagnosis.

Adolescent↗
PubMed1977

Evidence for the lack of a carrier effect in the solvent extraction and determination of octopamine by gas chromatography mass spectrometry.

It has been shown that there is no significant carrier effect when low levels of [3H]octopamine (100 pg) are extracted by ethyl acetate from aqueous solutions containing a 10(3) or 10(6) times excess of unlabelled octopamine. It is also shown that there is no carrier effect when low levels of octopamine as the tetrakis-TMS derivative are injected with 100 times the amount of the [2H3] analogue on an SE 30 column.

Chromatography, Gas↗
PubMed1977

Chemical and radiochemical stability of the adrenal-scanning agents, 6beta-iodomethyl-19-norcholest-5(10-en-3beta-ol and 19-iodocholest-5-en-3beta-ol.

The chemical stabilities of the adrenal-scanning agents, 6beta-iodo-methyl-19-norcholest-5(10)-en-3beta-ol (6-iodomethylnorcholesterol) and 19-iodocholest-5-en-3beta-ol (19-iodocholesterol), and several of their derivatives were examined by 13C nuclear magnetic resonance. Neat 6-iodomethylnorcholesterol, sealed in glass under nitrogen and stored at 0 degrees C, remains 98 mole% chemically pure for 3 months. Neat 19-iodocholesterol, stored in the dark at 25 degrees C, remains 98 mole% chemically pure for 3 months. Either 6-iodomethylnorcholesterol-125I or-131I, informulation and stored at 5 degrees C, will remain greater than 97% radiochemically pure for at least 15 days. Labelled 19-iodocholesterol, formulated and stored under the same conditions, shows 20% decomposition after 3 weeks and 40% after 6 weeks.

Adrenal Glands↗
PubMed1977

Ruptured mycotic splenic artery aneurysm: angiographic diagnosis.

A case of ruptured artery aneurysm is presented, emphasizing the pre-operative angiographic diagnosis of a difficult clinical problem. Although some patients have been operated on without angiography, this may prove of some difficulty if the diagnosis is not suspected. Awareness of potential routes of spread along soft tissue planes from the pancreatic bed may be of considerable importance in establishing the diagnosis.

Aneurysm, Infected↗
PubMed1977

Physiological and morphological factors associated with successful fencing performance.

The relation between fencing success during a season of intercollegiate competition and various physiological and morphological variables were determined in 14 fencers. Bivariate and multiple regression analysis was used to determine the extent to which the independent variables, individually and collectively, accounted for the variance in two measures of fencing success. The fencing scores correlated significantly with VE max, Vo2 max, the 2 km run, and weight, while there was no significant correlation between the fencing scores and submaximal heart rate at 6 mph, and 1 min steptest score, or other morphological measurements. Cardiorespiratory fitness variables of Vo2 max and VE max accounted for the greatest variance in each of the two fencing scores (57.7 and 58.1%, respectively). Although morphological factors play a role in fencing success, their influence is small when physiological factors are accounted for. Future energy-cost studies are suggested to determine the physiological basis for the relationship between cardiorespiratory fitness and fencing success.

Adipose Tissue↗