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Biomedical subjects

E Levine

Publications and source records attributed to E Levine.

At least 109 records · Page 6Linked to original sources
PubMed1987

Nontransducing rhodopsin.

Rhodopsin is converted by light to an active photoproduct that triggers the transduction cascade. The active photoproduct must then be inactivated by some kind of chemical modification. The question addressed here is whether photoconversion of the inactive photoproduct to rhodopsin creates a modified form of rhodopsin that is unable to support transduction. This question was investigated in ultraviolet receptors of Limulus median eye by measuring the relative quantum efficiency of excitation after photoregeneration of rhodopsin from the inactive photoproduct. The results show that when this newly created rhodopsin absorbs a photon, no receptor potential is generated; i.e., the pigment is nontransducing. A dark process requiring 30-60 min returns rhodopsin to its transducing form.

Animals↗
PubMed1987

UV-inducible DNA repair in the cyanobacteria Anabaena spp.

Strains of the filamentous cyanobacteria Anabaena spp. were capable of very efficient photoreactivation of UV irradiation-induced damage to DNA. Cells were resistant to several hundred joules of UV irradiation per square meter under conditions that allowed photoreactivation, and they also photoreactivated UV-damaged cyanophage efficiently. Reactivation of UV-irradiated cyanophage (Weigle reactivation) also occurred; UV irradiation of host cells greatly enhanced the plaque-forming ability of irradiated phage under nonphotoreactivating conditions. Postirradiation incubation of the host cells under conditions that allowed photoreactivation abolished the ability of the cells to perform Weigle reactivation of cyanophage N-1. Mitomycin C also induced Weigle reactivation of cyanophage N-1, but nalidixic acid did not. The inducible repair system (defined as the ability to perform Weigle reactivation of cyanophages) was relatively slow and inefficient compared with photoreactivation.

Cyanobacteria↗
PubMed1987

Spontaneous subcapsular and perinephric hemorrhage in end-stage kidney disease: clinical and CT findings.

Clinical, CT, and pathologic findings were analyzed in six patients with spontaneous subcapsular or perinephric hematomas complicating end-stage kidney disease. Renal failure had been managed by hemodialysis in four patients, by renal transplantation in one, and by conservative methods in one. All patients had nonspecific abdominal pain. CT clearly showed in all cases that the pain resulted from hemorrhage and also revealed the extent and location of hematomas. In addition, in four patients, CT showed underlying acquired cystic kidney disease that was the probable cause of hemorrhage. In one of these patients, CT also showed a renal cell carcinoma in the opposite kidney. Other causes for renal hemorrhage encountered in the series included renal infarction due to small vessel disease, heparinization during hemodialysis, and thrombocytopenia. Abdominal CT is a useful technique for evaluating patients with end-stage renal disease who have abdominal pain or who exhibit clinical evidence of blood loss.

Adult↗
PubMed1987

Malignant nerve-sheath neoplasms in neurofibromatosis: distinction from benign tumors by using imaging techniques.

Malignant peripheral nerve-sheath neoplasms frequently complicate neurofibromatosis causing pain, enlarging masses, or neurologic deficits. However, similar findings sometimes also occur with benign nerve neoplasms. Our study was done retrospectively to determine if imaging techniques can differentiate malignant from benign nerve tumors in neurofibromatosis. Eight patients with symptomatic neoplasms (three benign, five malignant) were studied by CT in eight, MR in six, and 67Ga-citrate scintigraphy in seven. Uptake of 67Ga occurred in all five malignant lesions but not in two benign neoplasms studied. On CT or MR, all eight lesions, including three benign neoplasms, showed inhomogeneities. Of five lesions with irregular, infiltrative margins on CT or MR, four were malignant and one was benign. Of three lesions with smooth margins, one was malignant and two were benign. One malignant neoplasm caused irregular bone destruction. Accordingly, CT and MR could not generally distinguish malignant from benign lesions with certainty. However, both CT and MR provided structural delineation to help surgical planning for both types of lesion. 67Ga scintigraphy appears promising as a screening technique to identify lesions with malignant degeneration in patients with neurofibromatosis. Any area of abnormal radiogallium uptake suggests malignancy warranting further evaluation by CT or MR. Biopsy of any questionable lesion is essential.

Adolescent↗
PubMed1987

Cryptosporidiosis in Haitian children.

We used a modified acid-fast stain to detect Cryptosporidium oocysts in unconcentrated stools from 824 Haitian children less than 2 years of age with acute diarrhea. Oocysts were identified in stools from 17.5% of 291 children seen at a rural dispensary and in 16.3% of stools from 533 children in an urban hospital. Children with cryptosporidiosis were identified throughout a 22-month period from October 1982 to July 1984, without seasonal predilection. Cryptosporidiosis was twice as common in infants greater than 6 months of age than in younger infants. Cryptosporidium oocysts were rarely found in stools of infants receiving only breast milk. The clinical presentation of children with cryptosporidiosis was similar to other patients with diarrhea who did not have cryptosporidiosis. No asymptomatic Cryptosporidium infections were detected among 71 family members of 31 children with cryptosporidiosis. Three of the 71 family members less than 3 years of age were found to have diarrhea and Cryptosporidium oocysts. In follow-up studies of 31 patients, oocysts persisted in stools for a mean of 14 days (range 5-31 days). Duration of oocyst excretion was directly correlated with duration of diarrhea. These findings suggest that Cryptosporidium is an important cause of acute self-limited diarrheal illness to Haitian children.

Breast Feeding↗
PubMed1986

Computed tomography in the diagnosis and follow-up of American Burkitt's lymphoma.

CT scans of Burkitt's lymphoma in 8 American patients are presented. Computed tomography was the major diagnostic imaging modality in 4, and the abdomen was the most commonly involved site in our patients. CT was found to be the method of choice for diagnostic purposes and for assessing the size of abdominal masses. Furthermore, because of the relative effectiveness of modern chemotherapeutic agents in treatment of this type of lymphoma, CT did and can play a unique role in follow-up of these cases during therapy.

Abdominal Neoplasms↗