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Biomedical subjects

M Feld

Publications and source records attributed to M Feld.

12 recordsLinked to original sources
PubMed1992

Characterization of ultraviolet laser-induced autofluorescence of ceroid deposits and other structures in atherosclerotic plaques as a potential diagnostic for laser angiosurgery.

Unstained frozen sections of normal and atherosclerotic human aorta and coronary artery were examined using histochemical and fluorescence microscopic techniques to identify the structures responsible for autofluorescence under 351 to 364 nm laser excitation. These structures included elastin and collagen in normal and atherosclerotic specimens, calcium deposits in calcified plaques, and granular or ring-shaped deposits histochemically identified as ceroid found in both calcified and non-calcified plaques. Qualitatively, both the color and intensity of ceroid autofluorescence differed greatly from that of elastin or collagen. The emission spectra of elastin, collagen, and ceroid were examined by microscopic spectrofluorimetry, and were found to differ significantly as well. When compared with spectra of elastin and collagen, spectra of ceroid were broader, shifted to the red, and were somewhat resistant to bleaching. We conclude that detection of laser-induced ceroid autofluorescence may aid in identifying plaques for laser ablation.

Angioplasty, Laser↗
PubMed1991

Traumatic rupture of the thoracic aorta.

Because the diagnosis of a traumatic rupture of the aorta can be subtle, a high index of clinical suspicion must be maintained to arrive at a prompt and correct diagnosis. When chest radiography shows that the mediastinum is greater than 8 cm in width or that the arch or descending aorta are obscured, direct transfemoral arteriography remains the procedure of choice in hemodynamically stabilized patients. At the present time, computed tomography is not recommended as a definitive diagnostic modality.

Adult↗
PubMed1989

Lyme carditis: an important cause of reversible heart block.

Lyme disease is a tick-borne spirochetal infection, characterized by erythema chronicum migrans and an acute systemic illness. The disease is endemic in many parts of the north-eastern United States. Without treatment, late rheumatic, neurologic, and cardiac complications frequently occur. We report four serologically confirmed cases of Lyme carditis in previously healthy young men (mean age, 45 years) from endemic areas. Each presented with severe symptomatic atrioventricular block, three with episodes of prolonged ventricular asystole. Two had permanent pacemakers implanted (one was later removed), and another, very nearly did, before diagnosis. All four patients were treated with antibiotics, and in each case their rhythm returned to sinus, though one patient has Wenckebach second degree block with atrial pacing at 120 beats/min 16 months later. Carditis occurs in 4% to 10% of cases of Lyme disease and usually begins 3 to 6 weeks after the initial illness. It manifests as a transient myocarditis with varying degrees of atrioventricular block. The diagnosis is made primarily on clinical grounds and confirmed by serologic testing. Temporary cardiac pacing is frequently needed by patients who have severe heart block with hemodynamic instability. The evidence suggests that, in most cases, the block is at the level of the atrioventricular node. The block generally resolves completely with antibiotic treatment. Complete heart block rarely persists more than 1 week and the long-term prognosis appears to be excellent. Consideration and prompt recognition of this potentially lethal, but reversible, cause of heart block is crucial in order to avoid inappropriate permanent pacemaker implantation.

Adult↗
PubMed1988

Gas volume quantitation during argon ion laser ablation of atheromatous aorta in blood and 0.9% saline media with an optically shielded catheter.

Using an optically shielded fiber optic laser catheter, the amount of gas produced when firing an argon ion laser into 0.9% saline solution or blood alone and into atheromatous aorta in either a blood or 0.9% saline medium was quantitated. Energies from 0.25 to 4 joules (J) were used at powers of 2, 5, and 8 W. We found that total volume of gas produced is small not only at equilibrium (0.3 +/- 0.1 microliter/J when firing in blood alone and also when ablating aorta in blood or saline media) but also at peak (2.5 +/- 0.2 microliters/J firing in blood alone and 1.0 +/- 0.1 microliter/J or 0.9 +/- 0.1 microliter/J when ablating aorta in saline or blood, respectively). Because these volumes are small, a clinically significant event from a gas embolus is unlikely during intravascular laser ablation of atheromatous plaque in the energy and power range studied. No gas was quantitated when firing the argon ion laser into 0.9% saline solution alone. The peak gas volume when firing in blood alone was significantly greater than that produced in the other chamber environments. This is thought to be due to increased absorption of argon laser light by hemoglobin. The gas volumes produced by lasing aorta in 0.9% saline or blood were not statistically different.

Angioplasty, Balloon↗
PubMed1979

The influence of cold insoluble globulin on platelet morphological response to substrata.

Light microscopic studies have been carried out on the attachment and morphological responses of washed human platelets in serum-free medium to fibrinogen-coated, collagen-coated and uncoated tissue culture plastic substrata. Platelets were observed to attach to the substratum, extend filipodia and undergo spreading. Subsequently, lysis of platelets occurred. On uncoated tissue culture plastic substrata, the addition of cold insoluble globulin to the incubations had no effect on the above morphological changes. On the other hand, on the protein coated substrata, there was very little platelet spreading or lysis without the addition of cold insoluble globulin.

Blood Platelets↗
PubMed1967

Diagnosis of gaucher's disease and niemann-pick disease with small samples of venous blood.

Enzymes which catalyze the hydrolysis of glucocerebroside and sphingomyelin have been demonstrated in preparations of washed human white blood cells. The level of activity of these respective enzymes is markedly decreased in leukocyte preparations obtained from patients with Gaucher's and Niemann-Pick diseases. Assay of these enzymes may be useful in the differential diagnosis of the sphingolipidoses.

Adolescent↗