Application of a fluorometric method to measure glutamate release from single retinal photoreceptors.

Release of the endogenous transmitter, glutamate, was measured from individual cone photoreceptors using a microfluorometric technique. The assay for glutamate was conducted within the lumen of a suction pipette, and was based on the fluorometric measure of the production of NADH from NAD+. This reaction was catalyzed by glutamate dehydrogenase contained in the pipette. Upon introduction of glutamate to the pipette, an increase in the NADH fluorescence was observed, representing the stoichiometric conversion of glutamate to NADH. The fluorescent signal was quantified, allowing an estimate of glutamate release from a single cone upon depolarization. The release observed was elicited upon depolarization of the cell with extrinsic current, and was detectable simultaneous with stimulation of the cell. Depolarization-induced release of endogenous glutamate was from the synaptic pedicle of the cell, and this release decreased with subsequent stimulations. The decrease in the release could be briefly reversed by an increase in the depolarization current used, or by allowing the cell to rest for several minutes.     

Radiation dose reduction during hysterosalpingography: an application of scanning-beam digital radiography

Hysterosalpingography was performed in 31 patients by means of a low-dose scanning-beam digital radiographic system. The technique permits adequate evaluation of gynecologic abnormalities while allowing significant reduction in radiation: 2.4-mR (6.1 X 10(-7) C/kg) exposure to the skin and 0.7-mrad (7 X 10(-6) Gy) mean dose to the ovaries per image obtained. Sixteen patients demonstrated readily recognizable and documented abnormalities, corroborated by laparoscopy, laparotomy, or other supportive evidence.     

Histological, histochemical and electron microscopic changes of the placenta induced by maternal exposure to hyperthermia in the rat.

Both clinical and experimental investigations have shown that maternal hyperthermia during critical stages of embryo development can induce malformations in the offspring. Studies of the effect of heat stress on the placental functions are limited to the ewes, but that on microscopic structure is unknown. In the present study, rats were exposed to 41 or 42 degrees C for 1 h on gestation day (GD) 9. The controls were sham treated. Fetuses and placentas were collected on GD 20. Intrauterine growth retardation (IUGR) and several craniofacial malformations were observed in the fetuses of the heat-treated group. The placentas of the 42 degrees C group were significantly lighter in weight than those of the control. Light microscopy (LM) revealed thickening, hyalinization and occasional lymphocytic infiltration of the decidua basalis. Giant cells were prominent and glycogen cells had degenerated, leaving behind large cysts in the basal (spongy) zone. Best's carmine stain with or without diastase indicated the reduction in number and degeneration of glycogen cells and cyst formation. The labyrinthine zone was relatively thin in comparison to that of the controls. Perivascular fibrosis and paucity of vascularization were other features of the placentas of the hyperthermia group. Electron microscopy (EM) revealed lipid droplet accumulation in the trophoblast, the presence of myelin bodies and an increased production of collagen in the basal zone. Perivascular fibrosis appeared to have contributed to placental barrier thickening. EM also revealed accumulation of glycogen and lipid droplets in the trophoblasts and fibrin secretion into the extracellular space of the labyrinthine zone. These data suggest that placental pathology possibly contributes to fetal growth retardation in maternally heat-stressed rat fetuses.     

Early inhibition of natural and interferon-activated killers in endometrial cancer patients treated with local radiotherapy

The present study was aimed at comparing the effect of clinical staging and radiotherapy on natural killer (NK) and interferon-activated killer (IAK) cell activity in a group of endometrial cancer patients receiving a total dose of 5,000 to 8,000 rads. We report that when compared to age-matched women, a significantly higher number and percentage of patients show low NK and IAK cell activity. At diagnosis, diminished NK activity was seen in about 20% of the patients, while IAK activity was low in 49% of these patients. There was no correlation between these deficiencies and the grade or stage of the disease. In contrast, radiotherapy induced deleterious effects on both populations of NK and IAK cells. These deleterious effects were more pronounced in patients showing a low level of spontaneous NK activity. In an attempt to understand better the mechanism by which the presence of cancer itself and/or radiotherapy affects these activities, we studied in greater detail changes in peripheral blood T-cell numbers and subsets. Before radiotherapy, all lymphocyte counts were within the normal range. In contrast, after radiotherapy the absolute numbers of all T-cell subsets were significantly decreased in the majority of the patients tested, OKT4+ cells being the most radiosensitive and Leu 7+ cells the most radioresistant.     

Solitary bronchioloalveolar carcinoma: CT criteria

The computed tomographic (CT) scans of 30 patients with solitary bronchioloalveolar carcinoma were reviewed. Common features at CT included the peripheral or subpleural location of a pulmonary mass (25 cases), pseudocavitation (18 cases), heterogeneous attenuation (17 cases), irregular margins forming a star pattern (22 cases), and pleural tags (21 cases). Using these CT criteria, four independent observers attempted to identify cases of bronchioloalveolar carcinoma from a larger sample of lung cancers and benign lesions by categorizing a series of test cases into four probability categories. Although the bronchioloalveolar carcinomas were correctly ranked in the two highest probability categories 75% of the time (in 45 of 60 cases), there was considerable overlap with other lung lesions, particularly with adenocarcinoma and large cell undifferentiated carcinoma. However, even though the typical features of bronchioloalveolar carcinoma are not invariable or highly specific, they are characteristic enough to suggest the diagnosis.