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Biomedical subjects

D Short

Publications and source records attributed to D Short.

At least 19 recordsLinked to original sources
PubMed1990

Intensive venous sampling paradigms disclose high frequency adrenocorticotropin release episodes in normal men.

Recent studies in the rat and rhesus monkey have disclosed apparently high frequency in vivo ACTH release episodes. While the circadian pattern of plasma ACTH concentrations has been known for many years, the exact frequency of ultradian pulsatile ACTH release in man is not clear, due in part to variable intensities of blood-sampling schedules and the limited availability of sensitive ACTH assays. In this study we used a new sensitive and specific immunoradiometric assay to measure plasma ACTH concentrations in blood sampled at 1) 2-min intervals for 3 h, followed by 4-min intervals for 4 more h in six men; and 2) 10-min intervals for 24 h in eight other men. An objective peak detection algorithm (Cluster) and cosinor analyses were used to assess the episodic pulsatility and circadian rhythmicity of ACTH. Comparisons were made among the 2 min (3 h), 4, 8, and 12 min (7 h), and 10 min (24 h) time series. Mean ACTH interpulse intervals were significantly different among the five sampling groups (P less than 0.00001). Sampling every 2 min yielded a mean ACTH interpulse interval of 18 min, which was significantly shorter than the mean interpulse intervals of 35, 53, 52, and 73 min resulting, respectively, from sampling every 4, 8, 10, and 12 min (P less than 0.05). In contrast, maximal peak ACTH amplitudes (picomoles per L or percent increase) did not vary as a function of sampling frequency. The 24-h plasma ACTH concentration time series showed significant diurnal variation, with a mean circadian amplitude of 0.95 +/- 0.15 pmol/L occurring at 1008 h (+/- 25 min). Cosinor analysis of various ACTH pulse parameters deduced from the 24-h time series revealed significant circadian rhythmicity in the ACTH peak maxima (P less than 0.05), peak increments (P less than 0.05), and prepeak nadir (P less than 0.05) concentrations, but not in ACTH interpulse intervals. We conclude that in men, 1) intensive sampling at 2-min intervals unmasks high frequency ACTH release episodes that cannot be detected at conventional sampling rates; and 2) ACTH peak amplitude, but not frequency, varies significantly during the course of circadian changes in the plasma ACTH concentrations.

Adrenocorticotropic Hormone↗
PubMed1989

Treatment of symptomatic peripheral atherosclerotic disease with a rotational atherectomy device.

Narrowings 70 to 90% in diameter in 3 iliac, 4 superficial femoral and 2 popliteal arteries were crossed and atherectomized successfully in 6 patients using the Squibb Rotablator under angiographic guidance during surgical bypass procedures on these arteries. The Rotablator consists of a 1.25 to 4.5 mm diameter oblong burr with tiny diamond blades mounted on a flexible shaft, which tracks over a spring-tip guidewire and rotates at speeds greater than 120,000 rpm. All stenoses were reduced to less than or equal to 50% of the normal luminal diameter. No significant complications occurred. Of the 6 patients having the atherectomy procedure, 5 were reevaluated by duplex Doppler measurements 1.5 to 5.5 (mean 3.5) months after atherectomy and found to be patient with only mild residual flow disturbance. Repeat follow-up by angiography after a mean of 5.2 months, however, showed only 3 (37%) of the atherectomized segments in 3 patients to still be patent. All were symptomatically improved. Of the effluent particles analyzed, 90% were less than 8 microns in size, while only 5% reached 250 microns. With improvements in technique, the largest particles were 150 to 180 microns, constituting only 1.4% of effluent debris. Samples of the effluent from 2 patients were injected in vivo into the left coronary system of 2 pigs. There were no acute hemodynamic or electrocardiographic complications or pathologic evidence of muscle necrosis or vascular thrombosis 18 to 48 hours later. These preliminary results with respect to feasibility and safety of the Rotablator are promising.

Adult↗
PubMed1987

Relative displacements in muscle and tendon during human arm movements.

1. X-ray, cine and video recordings were made of the movement of radio-opaque markers injected into the musculo-tendinous junctions of biceps brachii muscle. 2. In strong isometric contractions, the distal tendon of the long head of biceps lengthened by about 2% of its estimated rest length. 3. During voluntary isotonic elbow flexion-extension movements at frequencies up to 5.5 Hz there was no detectable phase shift between intramuscular and joint displacements. 4. In the fastest alternating movements (5.5-6.7 Hz) small phase advances developed in the muscle. 5. We conclude that human tendons do stretch during muscle contraction, but not enough to cause intramuscular phase reversals in rapid unloaded movements. This in turn means that muscle spindles shorten and lengthen virtually in phase with joint movements under most conditions.

Arm↗
PubMed1984

Positive T wave overshoot as a sign of ventricular enlargement.

A consecutive series of 86 patients with an inverted T wave showing terminal positivity (overshoot) of a specific pattern in the resting electrocardiogram were studied. Patients with bundle branch block or electrocardiographic evidence of acute infarction and those taking digoxin or a similar drug were excluded. In 67 patients the heart was examined by echocardiography and in a further two by direct inspection. Sixty six of the 69 patients had an abnormal thickness of the left (or right) ventricle or a calculated left ventricular mass greater than 200 g. Seven of the patients examined by echocardiography had clinically pure ischaemic heart disease; all showed evidence of left ventricular enlargement. In only 39 of the 63 patients with anatomical evidence of left ventricular hypertrophy or dilatation did the electrocardiogram satisfy the standard voltage criterion of left ventricular hypertrophy. In the absence of acute infarction, bundle branch block, or digitalisation positive T wave overshoot of the pattern described is a sign of increased ventricular mass.

Adolescent↗
PubMed1983

Significance of asymmetrically inverted T wave.

Two consecutive series of patients with a T wave asymmetry ratio of 2.0 or greater have been studied. Patients with bundle-branch block or who were on digoxin or a similar drug were excluded. In 50 of the 69 patients, the heart was examined either by echocardiography or by direct inspection. Sixty-one of the 69 patients had diseases commonly associated with left (or right) ventricular hypertrophy and/or dilatation. The remaining eight patients had clinically pure ischaemic heart disease. Of the 50 hearts examined by echocardiography or direct inspection (including six with pure ischaemic heart disease), 49 were found to have abnormal thickness of the left (or right) ventricle, or increased end-diastolic left ventricular diameter, or a combination of hypertrophy and dilatation. In 12 of the 47 patients with left ventricular hypertrophy or dilatation, the electrocardiogram did not satisfy the Sokolow and Lyon voltage criterion of left ventricular hypertrophy.

Adolescent↗
PubMed1981

Electrocardiogram of pure left ventricular hypertrophy and its differentiation from lateral ischaemia.

In routine reporting of electrocardiograms, a frequent problem is presented by the presence of repolarisation abnormalities (ST depression and/or T wave inversion) in the lateral leads without the accepted QRS voltage criterion of left ventricular hypertrophy. To help resolve this problem, the electrocardiograms of 41 patients with severe aortic stenosis who had no evidence of coronary disease were compared with the electrocardiograms of 20 patients with lateral myocardial infarction who had no clinical evidence of left ventricular hypertrophy. Nine of the patients with aortic stenosis were found to show repolarisation abnormalities in the lateral leads without the standard voltage criterion of left ventricular hypertrophy. The repolarisation pattern of aortic stenosis could frequently be distinguished from that of coronary disease by the presence of one or more of the following five features: depression of the J point, asymmetry of the T wave with rapid return to the baseline, terminal positivity of the T wave ("over-shoot"), T inversion in V6 greater than 3 mm, and T inversion greater in V6 than in V4.

Adult↗
PubMed1979

The anatomic basis for the occasional failure of transfemoral balloon catheter thromboembolectomy.

A Fogarty balloon catheter was advanced from the common femoral artery through the popliteal artery and its branches in 15 cadavers. The catheter passed into the peroneal branch 89% of the time. In all 15 cadavers, the peroneal artery was the direct continuation of the popliteal artery and the arterior tibial and posterior tibial arteries branched off at varying angles from the popliteal. This provides an anatomic explanation for the occasional failure of transfemoral Fogarty catheter embolectomy of the leg. Our study suggests that if the patient's foot does not improve after Fogarty embolectomy, the popliteal artery should be exposed and the catheter directed into the shank arteries using vascular forceps.

Catheterization↗
PubMed1979

Eosinophilic fasciitis. A pathologic study of twenty cases.

This report presents a detailed light-microscopic evaluation of biopsies obtained from 20 patients with eosinophilic fasciitis, a newly recognized disorder characterized by inflammation and thickening of the deep fascia, hypergammaglobulinemia, and peripheral and tissue eosinophilia. Early in the course of the disease, the deep fascia and lower subcutis are edematous and infiltrated with lymphocytes, plasma cells, histiocytes, and eosinophils; these features are associated with impressive peripheral eosinophilia. As the illness progresses, these structures and eventually the dermis become collagenized, thickened, and sclerotic. Tissue eosinophilia may be focal or diffuse and is usually observed in the fascia and/or lower subcutis. Extracutaneous involvement has been limited to a chronic synovitis and tenosynovitis, the latter frequently associated with the carpal tunnel syndrome. Deposits of immunoglobulin and/or complement were found in five of eight biopsies studied by direct immunofluorescence, which suggests that an immunologic stimulus may be responsible for initiating this syndrome. Differential diagnoses are discussed.

Adult↗
PubMed1978

Angina.

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Adrenergic beta-Antagonists↗