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.     

Effect of dietary protein on renal tubular clearance of drugs in humans

Diet is one of many factors that influence the pharmacokinetics of drugs. The level of protein intake has been found to significantly influence drug metabolism and glomerular filtration, both of which play an important role in the clearance of drugs. Recently, a marked change, resulting from restricted dietary protein intake, has been reported in the handling of several drugs which are reabsorbed and/or secreted by the renal tubules. In studies of healthy volunteers on protein-restricted diets the renal clearance and fractional excretion of model compounds have been altered, falling to 30% of values obtained on normal diets in the case of the weak acids oxipurinol and uric acid; the fractional excretion of the weak base cimetidine has been increased by 30%. These studies have also found that the change in the renal clearance of both acids is sustained with prolonged dietary protein-calorie restriction, and that, for oxipurinol, the magnitude of the change is directly related to the quantity of protein in the diet, the change is related specifically to the protein content in the diet (and not the total calories), the onset of change is rapid, and on a low-protein diet the renal clearance undergoes marked diurnal variation. The mechanism for the alteration in tubular function is not clear, but may be related to renal haemodynamic changes or competition for transport associated with protein intake. Regardless of the mechanism, these results have important implications for pharmacokinetic research and clinical practice.     

Identification and localization of muscarinic acetylcholine receptor proteins in brain with subtype-specific antibodies

mRNAs encoding five genetically distinct muscarinic ACh receptors are present in the CNS. Because of their pharmacological similarities, it has not been possible to detect the individual encoded proteins; thus, their physiological functions are not well defined. To characterize the family of proteins, a panel of subtype-selective antibodies was generated against recombinant muscarinic receptor proteins and shown to bind specifically to each of the cloned receptors. Using immunoprecipitation, three receptor proteins (m1, m2, and m4) accounted for the vast majority of the total solubilized muscarinic binding sites in rat brain. These receptor subtypes had marked differences in regional and cellular localization as shown by immunocytochemistry. The m1-protein was present in cortex and striatum and was localized to cell bodies and neurites, consistent with its role as a major postsynaptic muscarinic receptor. The m2-receptor protein was abundant in basal forebrain, scattered striatal neurons, mesopontine tegmentum, and cranial motor nuclei; this distribution is similar to that of cholinergic neurons and suggests that m2 is an autoreceptor. However, m2 was also present in noncholinergic cortical and subcortical structures, providing evidence that this subtype may presynaptically modulate release of other neurotransmitters and/or function postsynaptically. The m4-receptor was enriched in neostriatum, olfactory tubercle, and islands of Calleja, indicating an important role in extrapyramidal function. These results clarify the roles of these genetically defined receptor proteins in cholinergic transmission in brain.(ABSTRACT TRUNCATED AT 250 WORDS)     

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.