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Biomedical subjects

L Morgenstern

Publications and source records attributed to L Morgenstern.

At least 55 records · Page 3Linked to original sources
PubMed1987

Chymotrypsin hydrolysis of X-phenyl hippurates. A quantitative structure-activity relationship and molecular graphics analysis.

The hydrolysis of a set of 28 X-phenyl hippurates by chymotrypsin was investigated. From the derived Km and kcat values a quantitative structure-activity relationship was developed. This equation shows that para substituents correlated by sigma- display only an electronic effect on the formation of the ES complex whereas meta hydrophobic substituents show a hydrophobic interaction correlated by pi in addition to their electronic effect. Meta polar substituents avoid contact with the enzyme and show only electronic effects on Km. Using the x-ray crystallographic coordinates for chymotrypsin and computer graphics, a model was constructed which is used to interpret the quantitative structure-activity relationship. As with a number of previously reported examples, we have found that when polar substituents have the option of binding to hydrophobic space or remaining in the aqueous phase they follow the latter possibility.

Binding Sites↗
PubMed1986

Coronary angioscopy in patients with unstable angina pectoris.

To visualize intracoronary lesions in patients with different clinical expressions of coronary disease, we performed coronary angioscopy during coronary-artery bypass surgery in 10 patients with unstable angina and 10 patients with stable coronary disease. We examined a total of 32 vessels, using flexible fiberoptic angioscopes. Twenty-two vessels had no acute intimal lesion; three had complex plaques, six had thrombi, and one had both. Coronary angiography correctly identified the absence of complex plaque and thrombus in 22 vessels, but it detected only one of four complex plaques and one of seven thrombi. On angioscopy, none of the 17 arteries in the patients with stable coronary disease had either a complex plaque or thrombus. In the "offending" arteries of the patients with unstable angina, all three patients with accelerated angina had complex plaques and all seven with angina at rest had thrombi. We conclude that angioscopy frequently reveals complex plaques or thrombi not detected by coronary angiography. Our observations suggest that anginal syndromes that are refractory to medical treatment can be caused by unstable pathologic processes in the intima. Ulceration of plaques may increase the frequency and severity of effort angina, and the subsequent development of partially occlusive thrombi may cause unstable rest angina.

Adult↗
PubMed1985

Relation of free silicone to human breast carcinoma.

Of 12 women with carcinoma of the breast and coexistent silicone mastopathy, nine had had injections of liquid silicone for breast augmentation; three had leaking silicone-gel prostheses. The clinical findings indicated that early diagnosis was obscured by the silicone-induced mastopathy, which rendered the interpretation of physical findings and mammograms difficult. The pathologic findings were suggestive of a possible adverse effect of the presence of free silicone within the breast tissue, axillary nodes, and axillary fat. Although no causal relationship between silicone and breast carcinoma is implied, a heightened awareness of the possible coexistence of silicone mastopathy and breast carcinoma is necessary.

Adult↗
PubMed1985

Changing aspects of radiation enteropathy.

Fifty-two patients with radiation enteropathy secondary to radiation for abdominal or pelvic malignant neoplasms are described. This series (1977 to 1984) is compared with a series of 50 patients from the same institution over an earlier period (1961 to 1977). Intestinal obstruction was the principal complication in both series; 96% of the patients underwent either intestinal resection or anastomotic bypass of the affected segment. Changes that have occurred since the last report are as follows: changes in source of radiation energy (linear accelerator); less evidence of mucosal damage; increased serosal reaction ("serosal peel"); and increased use of elemental diets, parenteral nutrition, and long intestinal tubes in surgical management. Since postoperative radiation injury occurs most frequently in the pelvis, new developments for the exclusion of small bowel from the pelvis during radiation are reviewed. Changes in fractionation of radiation dosage should also be considered in patients with enteric symptoms during radiation therapy.

Abdominal Neoplasms↗
PubMed1985

Pulsed ultraviolet lasers and the potential for safe laser angioplasty.

Endoscopic laser ablation of atheroma using continuous wave lasers is limited by imprecise control of thermal ablation, resulting in a crater that expands in width and depth, with thermal damage to adjacent normal tissue. We compared the gross and histologic effects of pulsed 308 mm excimer irradiation to continuous-wave Nd:YAG and Argon Ion laser irradiation, and pulsed 1,060 nm, 532 nm, 355 nm, and 266 nm laser irradiation in 205 atherosclerotic aortic segments. In contrast to the continuous-wave Nd: YAG, Argon Ion, and pulsed 1,060 nm, 532 nm, and 355 nm laser irradiation, which produced gross and histologic evidence of uncontrolled ablation, the 308 nm and 266 nm pulsed lasers induced incisions that conformed precisely to the beam configuration without gross evidence of thermal injury. The incision edges from these two lasers were histologically smooth and comparable to a scalpel incision. Our histologic findings suggest that rapid, precise endoscopic ablation of vascular and nonvascular tissue can be performed at these shorter pulsed wavelengths with very high precision with relatively little damage or risk to adjacent tissue.

Aorta, Abdominal↗
PubMed1985

Laser ablation of human atherosclerotic plaque without adjacent tissue injury.

Seventy samples of human cadaver atherosclerotic aorta were irradiated in vitro using a 308 nm xenon chloride excimer laser. Energy per pulse, pulse duration and frequency were varied. For comparison, 60 segments were also irradiated with an argon ion and an Nd:YAG (neodymium:yttrium aluminum garnet) laser operated in the continuous mode. Tissue was fixed in formalin, sectioned and examined microscopically. The Nd:YAG and argon ion-irradiated tissue exhibited a central crater with irregular edges and concentric zones of thermal and blast injury. In contrast, the excimer laser-irradiated tissue had narrow deep incisions with minimal or no thermal injury. These preliminary experiments indicate that the excimer laser vaporizes tissue in a manner different from that of the continuous wave Nd:YAG or argon ion laser. The sharp incision margins and minimal damage to adjacent normal tissue suggest that the excimer laser is more desirable for general surgical and intravascular uses than are the conventionally used medical lasers.

Aorta↗
PubMed1985

Television choledochoscopy.

Present techniques of intraoperative cholangiography and choledochoscopy have not completely solved the problem of the common bile duct stone that is missed. Televised choledochoscopy provides an improved imaging technique which should facilitate stone retrieval. A similar television endoscopic technique has already become standard among orthopedic surgeons performing diagnostic and therapeutic arthroscopy. This equipment can be shared by surgeons specializing in orthopedic or general surgery.

Endoscopy↗
PubMed1984

Hamartomas of the spleen.

A study of 12 cases of splenic hamartomas, rare benign lesions of the spleen, included one case of spontaneous rupture of a hamartoma that required emergency operation and two cases of hamartomatosis with splenomegaly. An increased incidence of accessory spleens was also noted. Therefore, although rarely symptomatic, hamartomas may occasionally be of clinical importance. Surgeons should be aware of these lesions in the differential diagnosis of splenic tumors that appear as filling defects on scintiscan or as splenic masses on abdominal exploration. Since it may also be a source of spontaneous splenic rupture, it should be considered as one of the rare causes of such an occurrence.

Adult↗
PubMed1984

Effect of preoperative irradiation on healing of low colorectal anastomoses.

The effect of preoperative irradiation on the healing of low colorectal anastomoses was studied experimentally. In 12 dogs in whom preoperative irradiation of 4,000 rads was given before low colorectal stapled anastomosis was performed, anastomotic leakage occurred in 66 percent. More than half of the anastomotic leaks were associated with either severe sepsis or death. In a matched group of control animals that underwent stapled anastomoses without irradiation, no anastomotic complications occurred. The clinical implications of this study are that stapled anastomoses in irradiated colon are at serious risk of anastomotic dehiscence and, therefore, should be protected with a proximal colostomy.

Animals↗
PubMed1984

Effects of choledochojejunostomy with Roux-en-Y exclusion on dimethylhydrazine induced neoplasms in rats.

The role of biliary secretions was studied in the development of neoplasms in the small intestine and colon of rats treated with 1,2-dimethylhydrazine (DMH). Sixty-eight female Sprague-Dawley rats underwent either no operative procedure or choledochojejunostomy with or without a Roux-en-Y exclusion. All animals then received weekly subcutaneous injections of DMH at 20 mg/kg for 26 weeks and were subsequently sacrificed. The largest number of neoplasms was found in the proximal duodenum, within 3 cm distal to the pylorus, in the control as well as both operative groups. In addition, only six neoplasms developed in relation to the choledochojejunostomy site in rats undergoing choledochojejunostomy only, and no neoplasms were noted at this location in the animals undergoing choledochojejunostomy with Roux-en-Y exclusion. These results suggest that the distribution of enteric neoplasms in DMH treated rats does not depend on excretion of active carcinogen in bile.

1,2-Dimethylhydrazine↗