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Biomedical subjects

T Mann

Publications and source records attributed to T Mann.

At least 73 records · Page 4Linked to original sources
PubMed1977

Effect of angina on the left ventricular diastolic pressure-volume relationship.

The increased left ventricular end-diastolic pressure associated with myocardial ischemia was studied in 19 patients at cardiac catheterization. Single plane left ventriculograms were performed using high fedelity micromanometer tipped catheters before and immediately following rapid atrial pacing. Left ventricular diastolic properties were evaluated by constructing diastolic pressure-volume curves from the simultaneous pressure and volume data. In seven control patients, there was no significant change in left ventricular hemodynamics or the diastolic pressure-volume curve after atrial pacing. Twelve patients with significant coronary artery disease developed angina during pacing and had an increased left ventricular end-diastolic pressure (18 +/- 2 mm Hg, control, vs 30 +/- 2 mm Hg, angina, P less than .01) in the immediate post-pacing period. In these patients, the post-pacing ejection fraction was modestly decreased (0.63 +/- 0.03, control, vs 0.57 +/- 0.03, angina P less than 0.01), and left ventricular volumes at end systole (59 +/- 8 cc, control, vs 74 +/- 9 cc, angina, P less than 0.0125) were increased. The post-pacing diastolic pressure-volume curves in all 12 patients were shifted upward as compared with control so that for any given diastolic volume, pressure was higher during angina. The data indicate that the increased left ventricular diastolic pressure during myocardial ischemia is the result of both impaired left ventricular systolic performance and altered left ventricular diastolic properties.

Adult↗
PubMed1977

Contractile state of the left ventricle in man as evaluated from end-systolic pressure-volume relations.

End-systolic pressure (PES), volume (VES), wall tension (TES) and circumference (CES) of the human left ventricle were studied at cardiac catheterization in 24 subjects with varying degrees of left ventricular dysfunction. Acute alterations in systolic load consistently resulted in changes in VES and CES, with a smaller volume and circumference characterizing the lower systolic load in each subject. End systolic pressure-volume lines were constructed by plotting PES against VES at the higher and lower systolic load in each subject. The slope of the resultant lines was considerably steeper for normal than for poorly contractile left ventricles. Vo, the volume axis intercept of the line (i.e., the theoretical VES at PES = O) was significantly smaller for normal than for poorly contractile ventricles. Similar findings were noted for Co, the theoretic end-systolic circumference at zero end-systolic ventricular wall tension. Post-extrasystolic potentiation resulted in decreased VES and CES with no change in PES and only a slight fall in TES. In conclusion, end-systolic pressure-volume and tension-circumference relations reflect the contractile state of left ventricular myocardium. Quantitation of these relationships may provide a useful new approach to the assessment of myocardial function in man.

Blood Pressure↗
PubMed1977

Effects of sodium nitroprusside on left ventricular diastolic pressure-volume relations.

The effect of sodium nitroprusside on the relationship between left ventricular pressure and volume during diastole was studied in 11 patients with congestive heart failure. Nitroprusside was infused to lower mean arterial pressure approximately 20-30 mm Hg. High fidelity left ventricular pressures were recorded in all patients simultaneously with left ventricular cineangiography (biplane in eight and single plane in three patients), allowing precise measurement of pressure and volume throughout the cardiac cycle. Left ventricular diastolic pressure-volume curves were constructed in each patient from data obtained before and during nitroprusside infusion. In 9 of 11 patients there was a substantial downward displacement of the diastolic pressure-volume curve during nitroprusside infusion, with left ventricular pressure being lower for any given volume with nitroprusside. Serial left ventricular cineangiograms performed 15 min apart in six additional subjects who did not receive sodium nitroprusside showed no shift in the diastolic pressure-volume relation, indicating that the shift seen with nitroprusside was not due to the angiographic procedure itself. A possible explanation for the altered diastolic pressure-volume relationships with nitroprusside might be a direct relaxant effect of nitroprusside on ventricular muscle, similar to its known relaxant effect on vascular smooth muscle. Alternatively, nitroprusside may affect the diastolic pressure-volume curve by affecting viscous properties or by altering one or more of the extrinsic constraints acting upon the left ventricle.

Aorta↗
PubMed1977

Toxicity of exogenous fatty acid peroxides towards spermatozoa.

The toxicity of unsaturated fatty acids towards spermatozoa was shown to be directly related to their degree of peroxidation. The toxicity was manifested by an immediate arrest of motility and irreversible loss of respiratory and fructolytic activity. Repeated washing of spermatozoa, or the addition of fructose, lactate, or ATP, failed to restore these functions. The structural damage incurred as a result of the fatty acid peroxides was particularly evident in the acrosomal region. Partial protection from the adverse effects of these peroxides was provided by prior treatment of spermatozoa with dialysed egg yolk or milk, but tocopherol, albumin and mercapto-ethanol were ineffective. It is suggested that lipid peroxides or their degradation products, whether introduced exogenously or derived from the peroxidation of endogenous phospholipids in semen, constitute a potential hazard to the functional integrity of spermatozoa.

Animals↗
PubMed1977

Damage to ram spermatozoa by peroxidation of endogenous phospholipids.

We examined the damaging effects on spermatozoa of endogenous phospholipid peroxidation brought about by aerobic incubation at 37 degrees C in the presence of 0-5 mM-ascorbic acid and 0-5 mM-FeSO4. As well as becoming immotile, such peroxidized spermatozoa also lost, through leakage, certain intracellular enzymes into the surrounding medium, on a scale resembling that produced by cold shocking non-peroxidized spermatozoa. Morphological observations revealed that peroxidation damaged the plasma membrane, particularly in the region of the acrosome. Further experiments showed that lipid peroxidation irreversibly abolished the fructolytic and respiratory activity of spermatozoa. The susceptibility of spermatozoa to peroxidation was greater when the cells were damaged before incubation with ascorbic acid and FeSO4. To some extent, peroxidation could be prevented, but not reversed, by the addition to sperm suspensions of dialysed egg yolk or dialysed bull seminal plasma. However, dialysed seminal plasma from ram, stallion or man had no protective effect.

Animals↗
PubMed1976

Evaluation of the functional state of male accessory glands by the analysis of seminal plasma.

In man, the seminal vesicles, together with the ampuls, constitutes the main source of seminal fructose. The human prostate produce citric acids, acid phosphatase and other enzymes. The exceeding high content of prostaglandins probably derives from the seminal vesicles. A combined analysis of fructose and citric acid in the ejaculate is desirable to state morphologic alterations or functional disturbances of the accessory glands. The well-known split ejaculate method enables to decide whether the ejaculatory process is normal, slight or heavily disturbed. Variations in the morphology and secretory function of the accessory glands in different mammalian species are pointed out. The influence of testosterone on the secretory function of the accessory glands is described and discussed in detail.

Animals↗
PubMed1975

Assessing the hemodynamic severity of acute aortic regurgitation due to infective endocarditis.

Nine patients who underwent aortic-valve replacement for acute aortic regurgitation due to infective endocarditis were studied for clinical features that may be useful in assessing the severity of this condition. The traditional physical signs of a wide pulse pressure were absent. As compared to a group of patients with chronic aortic regurgitation, the mean (plus or minus S.D.) pulse pressure (55 plus or minus 7 vs. 105 plus or minus 22 mm Hg), left ventricular end diastolic volume (146 plus or minus 28 vs. 264 plus or minus 64 ml per square meter) and stroke volume (89 plus or minus 22 vs. 163 plus or minus 57 ml per square meter) were significantly smaller in the acute group (P less than 0.01). Left ventricular pressure exceeded left atrial pressure in late diastole, causing premature closure of the mitral valve, and the degree of early closure reflected the increase in left ventricular end diastolic pressure. Premature closure of the mitral valve was demonstrated by echocardiography in all patients. Those with echocardiographic signs of very early mitral-valve closure have severely volume-overloaded ventricles and are candidates for early valve replacement.

Acute Disease↗
PubMed1975

Biochemistry of stallion semen.

Stallion semen has several chemical characteristics not commonly encountered in other animals. It contains very little fructose and the spermatozoa possess only limited fructolytic ability under anaerobic conditions. By determining some of the characteristic constituents such as ergothioneine, citric acid, glycerylphosphorylcholine and certain glycosidases, it is possible to obtain a quantitative measure of the secretory contribution of the ampulla, seminal vesicle and epididymis, respectively, towards the final composition of the whole ejaculate. By analysing separately the various fractions of a split ejaculate, including the so-called tail-end sample, it is possible to detect and pinpoint abnormalities in the functional state of the various male accessory organs and in the entire process of ejaculation.

Animals↗
PubMed1975

How toys began.

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Egypt, Ancient↗