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Biomedical subjects

R F Shepherd

Publications and source records attributed to R F Shepherd.

6 recordsLinked to original sources
PubMed2001

Arteritis and brachial plexus neuropathy as delayed complications of radiation therapy.

Radiation-induced arteritis of large vessels and brachial plexus neuropathy are uncommon delayed complications of local radiation therapy. We describe a 66-year-old woman with right arm discomfort, weakness, and acrocyanosis that developed 21 years after local radiation for breast adenocarcinoma. Arteriography revealed arteritis, with ulcerated plaque formation at the subclavian-axillary artery junction, consistent with radiation-induced disease, and diffuse irregularity of the axillary artery. Electromyography showed a chronic brachial plexopathy. The patient's acrocyanosis, thought to be due to digital embolization from her vascular disease, improved with antiplatelet therapy. The concurrent combination of radiation-induced arteritis and brachial plexopathy is uncommon but should be considered in patients presenting with upper extremity pain or weakness after radiation therapy.

Adenocarcinoma↗
PubMed1989

Hypertension and left ventricular diastolic function.

In recent years, there has been increased recognition of the relative importance of abnormalities of diastolic function in patients with essential hypertension. Indeed, diastolic dysfunction may be the earliest indicator of hypertensive heart disease. In this article, the mechanisms governing normal ventricular relaxation and the factors that may cause diastolic dysfunction are reviewed. Noninvasive clinical methods, particularly Doppler echocardiography and radionuclide angiography, for determination of diastolic function are outlined, and the limited experience in the management of hypertensive patients with abnormalities of diastolic function is discussed. When congestive heart failure develops in a patient with hypertension, it is especially important to determine whether it is due primarily to systolic or to diastolic left ventricular dysfunction.

Adrenergic beta-Antagonists↗
PubMed1979

The fate of acephate and carbaryl in water.

Acephate was resistent to hydrolysis in distilled, buffered water at pH 4.0 to 6.9, but not at pH 8.2, held for 20 days at 20 or 30 degrees C. The maximum conversion to methamidophos was 4.5% of the added acephate at pH 8.2 and 20 degrees C. The persistence of acephate in two natural waters, held at 9 degrees C for up to 42 and 50 days varied: 80% were recovered from pond water after 42 days, and 45% from creek water after 50 days. Rates of acephate degradation increased greatly when treated water samples were incubated in the presence of sediments, but not if water and sediment were autoclaved prior to treatment and incubation. The greatest conversion to methamidophos, 1.3% of the added acephate, had occurred after 42 days in pond water without sediment. Under the same conditions, carbaryl was less persistent than acephate in the natural waters: 18 to 20% were recovered from pond water after 42 days, and 37 to 40% from creek water after 50 days. The presence of sediment did not affect its degradation significantly. But more than 55% were recovered after 50 days if water and sediment were autoclaved prior to treatment and incubation. Neither acephate, methamidophos, nor carbaryl could be shown to escape from water into the atmosphere.

British Columbia↗
PubMedDate not supplied

Raynaud's phenomenon.

Much has been learned about the complexity of the local, humoral and nervous factors regulating the normal behavior of the skin blood vessels, and many studies have addressed how this knowledge might relate to the causation of primary Raynaud's disease. Despite this, the mechanism(s) responsible for the attacks of digital vasospasm remain an enigma. A key question is whether these attacks represent an exaggeration of the normal mechanisms causing constriction of the digital vessels with local cooling, or are due to a specific abnormality. In this article it is suggested that multiple factors are responsible, including the possibility of co-transmitters released with norepinephrine from the sympathetic nerves, increased activation of beta 2-adrenoceptors on the nerve endings, a shift in the balance of alpha 1 and alpha 2 adrenoceptors on the vascular smooth muscle and in endothelium-derived relaxing and contracting factors, and altered interactions of the endothelium with the blood elements including the effects of increased platelet serotonin.

Cold Temperature↗