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Biomedical subjects

A Khaki

Publications and source records attributed to A Khaki.

7 recordsLinked to original sources
PubMed2006

The effects of an electromagnetic field on the boundary tissue of the seminiferous tubules of the rat: A light and transmission electron microscope study.

Human beings are unavoidably exposed to ambient electromagnetic fields (EMF) generated from various electrical devices and from power transmission lines. Controversy exists about the effects of EMF on various organs. One of the critical issues is that EMF may adversely affect the reproductive system. In order to examine this 30 rat pups were exposed to 50 Hz EMF (non-ionising radiation) during in utero development (approximately 3 weeks) and postnatal life (5 weeks). Groups of exposed rats were subsequently left in an environment free of EMF in order to observe recovery, if any, from the changes induced by EMF on the boundary tissue of the seminiferous tubules. The materials were processed and observed under a light and a transmission electron microscope. In the experimental rats boundary tissue was found disrupted at various layers. This tissue showed infoldings, which were perhaps due to the loss of collagen and reticular fibrils from the inner and outer non-cellular layers. The outer non-cellular layer, which was thinner than that of the control, was stripped away from the myoid cell layer in multiple regions, giving a "blister-like" appearance. The myoid cells showed fewer polyribosomes, pinocytotic vesicles and glycogen granules. Most mitochondria were found to lack cristae. The connections between individual myoid cells were apparently lost. There were signs of recovery in the boundary tissue following withdrawal from EMF exposure. These results suggest that EMF exposure may cause profound changes in the boundary tissue of the seminiferous tubules. Therefore exposure to EMF may result in pathological changes that lead to subfertility and infertility.

Animals↗
PubMed1998

Extended aortic arch atherectomy.

We report 2 cases of extensive atherosclerosis of the ascending aorta, arch of the aorta, innominate artery, and bilateral carotid arteries treated surgically at St. Vincent and Veterans Administration Medical Centers of Portland, Oregon.

Aged↗
PubMed1997

Risk, diagnosis and management of prosthetic valve endocarditis: a review.

Prosthetic valve endocarditis (PVE) emerged approximately 37 years ago when the first human heart valve replacements were performed. PVE can be classified as 'early' or 'late' with the pathophysiology and etiologic organisms varying between the two subgroups. The incidence of PVE ranges up to 0.5% per patient-year for mechanical mitral valves and up to 1.0% per patient-year for other valves. The clinical presentation is similar to that of native valve endocarditis, with fever being the most prevalent sign. Diagnosis is based on a constellation of clinical signs and symptoms as well as echocardiographic evaluation of the valve and perivalvular tissues. An algorithm is set forth for diagnosis and management of patients with suspected PVE based on our personal experience and the published literature. Indications for surgery, the surgical approach and methods of PVE prophylaxis and prevention are discussed.

Algorithms↗
PubMedDate not supplied

Effects of transmyocardial laser revascularization by using a prototype pulsed CO2 laser on contractility and perfusion of chronically ischemic myocardium in a porcine model.

The purpose of this study was to test a new prototype pulsed CO2 laser to be used for transmyocardial laser revascularization (TMR). We wanted to determine whether it can reduce thermal damage and mitigate induced ischemia with improvement in contractile reserve of the heart as evidenced by contrast echocardiography at rest and under dobutamine stress. TMR is an emerging surgical strategy for treatment of myocardial ischemia not amenable to conventional percutaneous or surgical revascularization. Eleven pigs underwent ameroid occluder placement at the origin of the circumflex coronary artery. Six weeks later, occlusion of the circumflex coronary artery was documented. TMR was then carried out on 10 pigs by using a prototype pulsed CO2 laser that delivered 8-12 joules in 1.5 ms with a spot size of 1 mm. Six weeks after TMR, the pigs were restudied. The animals developed significant ischemia after 6 weeks of ameroid occlusion, at rest (p = 0.01) and at peak stress (p = 0.004). Wall motion for the ischemic segments improved significantly 6 weeks after TMR at peak stress (p = 0.02). TMR results in an improvement in wall motion in our model of chronic ischemia and improves wall motion score index more during induced stress than at rest.

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