Laser scanning tomography of the optic nerve head in ocular hypertension and glaucoma

BACKGROUND: This study evaluated the ability of laser scanning tomography to distinguish between normal and glaucomatous optic nerve heads, and between glaucomatous subjects with and without field loss. METHODS: 57 subjects were classified into three diagnostic groups: subjects with elevated intraocular pressure, normal optic nerve heads, and normal visual fields (n = 10); subjects with glaucomatous optic neuropathy and normal visual fields (n = 30); and subjects with glaucomatous optic neuropathy and repeatable visual field abnormality (n = 17). Three 10 degrees image series were acquired on each subject using the Heidelberg retina tomograph (HRT). From the 14 HRT stereometric variables, three were selected a priori for evaluation: (1) volume above reference (neuroretinal rim volume), (2) third moment in contour (cup shape), and (3) height variation contour (variation in relative nerve fibre layer height at the disc margin). Data were analysed using analysis of covariance, with age as the covariate. RESULTS: Volume above reference, third moment in contour, and mean height contour were significantly different between each of the three diagnostic groups (p < 0.001). Height variation contour showed no significant difference among the three diagnostic groups (p = 0.906). CONCLUSIONS: The HRT variables measuring rim volume, cup shape, and mean nerve fibre layer height distinguished between (1) subjects with elevated intraocular pressures and normal nerve heads, and glaucomatous optic nerve heads, and (2) glaucomatous optic nerve heads with and without repeatable visual field abnormality. This study did not directly assess the ability of the HRT to identify patients at risk of developing glaucoma. It is hypothesised that the greatest potential benefit of laser scanning tomography will be in the documentation of change within an individual over time.     

Factors involved in Schistosoma mansoni infection in rural areas of northeast Brazil

Two contiguous villages in Tracunhaém county (State of Pernambuco), endemic for schistosomiasis, were studied: Itapinassu (138 inhabitants) and S?o Joaquim (91 inhabitants). Agriculture predominates in the former region while ceramics is the main activity in the latter. Although no statistical difference was found regarding prevalence, severe infection (> 400 epg) predominated in Itapinassu, probably related to the kind of occupation. No association was found between parasite burden and severity of disease, in spite of the high infection rates for Schistosoma mansoni in both communities (approx. 60%). Typical epidemiological features of schistosomiasis such as age-related prevalences and intensities of infection (high in children, low in adults) were also mutual characteristics. Nutritional status determined through anthropometric evaluation was carried out by measuring specific anthropometric indicators. A deficit of energy intake, as well as vitamin A and riboflavin deficiencies were detected. The prevalence of moderate or severe undernutrition in patients under 18 years old was 21.9% in Itapinassu and 24.1% in S?o Joaquim. In this group an association was found between prevalence of schistosomiasis and chronic undernutrition. Similarly, for patients over 18 year old the prevalence of undernutrition was higher than 20%. However, in this case no association between nutritional status and either prevalence of schistosomiasis or parasite burden could be detected. The two communities had not been treated for eight years.     

Compatibility of parenteral nutrient solutions with selected drugs during simulated Y-site administration

The compatibility of 102 drugs with parenteral nutrient (PN) solutions during simulated Y-site administration was studied. Five milliliters of each of four representative PN solutions was combined in duplicate in a 1:1 ratio with 5-mL samples of solutions of 102 drugs in 5% dextrose injection or 0.9% sodium chloride injection. Visual examinations were performed in fluorescent laboratory light and under high-intensity monodirectional light, and turbidity was measured. Particle sizing and counting were performed for selected solutions. All evaluations were performed at intervals up to four hours; storage was at 23 degrees C. Most of the drugs tested were compatible with the PN solutions. However, 20 drugs exhibited various incompatibilities with one or more of the PN solutions. During simulated Y-site administration, four PN solutions were compatible with 82 of 102 drugs for four hours at 23 degrees C. Twenty drugs were incompatible with one or more of the PN solutions.     

DNA-drug interaction measurements using surface plasmon resonance

Formation of the blastocoel in early Xenopus embryos was studied with a novel biotin-permeability assay and newly generated tight junction markers. The blastocoel forms at the first cleavage division since functional tight junctions which excluded biotin and established a segregated intraembryonic compartment were found at the 2-cell and all subsequent developmental stages. Unexpectedly, tight junctions before the 64-cell stage were not at their normal apical positions, but were found deep in the embryos, up to 200 micron from the apical surface. In these positions, the tight junctions left large areas of ion permeable lateral membranes exposed to the extraembryonic environment, explaining why electrophysiological experiments record a decrease in embryonic input resistances concomitant with early cleavage stages. Immunohistochemistry revealed that the recessed tight junctions did not influence the distribution of C-cadherin and Na+,K+ATPase. Both markers were present apical to recessed tight junctions, indicating that the maintenance of polarization of these basolateral markers does not require tight junctions. With further development, tight junctions assumed an increasingly apical location until, by the 2000-cell stage, they occupied their conventional positions between the blastomeres at the apical/lateral membrane boundaries.     

Temporal relation of ATP-sensitive potassium-channel activation and contractility before cardioplegia

BACKGROUND: Pharmacologic treatment using potassium-channel openers (PCOs) before cardioplegic arrest has been demonstrated to provide beneficial effects on left ventricular performance with subsequent reperfusion and rewarming. However, the PCO treatment interval necessary to provide protective effects during cardioplegic arrest remains to be defined. The present study was designed to determine the optimum period of PCO treatment that would impart beneficial effects on left ventricular myocyte contractility after simulated cardioplegic arrest. METHODS: Left ventricular porcine myocytes were assigned randomly to three groups: (1) normothermic control = 37 degrees C for 2 hours; (2) cardioplegia = K+ (24 mEq/L) at 4 degrees C for 2 hours followed by reperfusion and rewarming; and (3) PCO and cardioplegia = 1 to 15 minutes of treatment with the PCO aprikalim (100 micromol/L) at 37 degrees C followed by hypothermic (4 degrees C) cardioplegic arrest and subsequent rewarming. Myocyte contractility was measured after rewarming by videomicroscopy. A minimum of 50 myocytes were examined at each treatment and time point. RESULTS: Myocyte velocity of shortening was reduced after cardioplegic arrest and rewarming compared with normothermic controls (63+/-3 microm/s versus 32+/-2 microm/s, respectively; p < 0.05). With 3 minutes of PCO treatment, myocyte velocity of shortening was improved after cardioplegic arrest to values similar to those of normothermic controls (56+/-3 microm/s). Potassium channel opener treatment for less than 3 minutes did not impart a protective effect, and the protective effect was not improved further with more prolonged periods of PCO treatment. CONCLUSIONS: A brief interval of PCO treatment produced beneficial effects on left ventricular myocyte contractile function in a simulated model of cardioplegic arrest and rewarming. These results suggest that a brief period of PCO treatment may provide a strategy for myocardial protection during prolonged cardioplegic arrest in the setting of cardiac operation.