Microvascular effects of atrial natriuretic peptide (ANP) in man: studies during high and low salt diet

OBJECTIVE: Infusion of ANP in anephric dogs causes a decrease in cardiac output and a rise in peripheral vascular resistance. This reduced cardiac output is possibly related to increased resistance to venous return generated in the microcirculation by venular constriction. The aim of the present study was to evaluate in healthy volunteers the effects of low-dose ANP infusion on both conjunctival and skin microcirculation during high or low salt diet. METHODS: ANP (7.5 ng/kg/min) and placebo were infused (i.v.) for 4 h, in random order on two separate days, in two groups of 10 healthy male volunteers each. One group was studied during high salt (ad libitum), and one group during low salt (55 mmol Na+/24 h) diet. Microvascular density and diameters of both conjunctiva and nailfold were studied using intravital videomicroscopy. Nailfold capillary red blood cell velocity (CBV) was studied using intravital videomicroscopy, and skin (thermoregulatory) blood flow (SBF) was studied using laser-Doppler fluximetry. RESULTS: In the high salt group ANP induced a 43% reduction in basal SBF as compared to an 18% reduction by placebo (P < 0.01). Parallel to SBF, ANP significantly reduced CBV (P < 0.02). Conjunctival capillary density decreased by 5% during ANP, while it increased by 28% during placebo (P < 0.05). No such effects of ANP were observed in the low salt group. Blood pressure and heart rate were not influenced by ANP infusion in neither group. CONCLUSION: Infusion of low doses of ANP into humans on an ad libitum salt diet results in vasoconstriction of the microcirculation, probably on the venular side. The lack of effect of ANP on the microcirculation during low salt diet may be related to a higher vascular tone prior to infusion.     

The palpal receptor organ of gamasid mites (Mesostigmata: Gamasina)]

PURPOSE: The aim of this prospective study was to evaluate the potentials and limits of Doppler waveform analysis of intrarenal vessels in patients with suspected renal artery stenosis. MATERIAL AND METHODS: In a three-year study we compared our colour Doppler results of 111 patients with the angiography results. Evaluated parameters were acceleration time (AT), acceleration index (AI) and early systolic peak (ESP). RESULTS: The sensitivity of severe stenoses (> or = 70%) was 89%. In moderate stenoses (50-70%) it was possible to increase the sensitivity from 56% to 76% if a comparison with the contralateral side was included. The specificity was 91%. Causes for limited sensitivity and specificity were poor examination conditions, stenoses of accessory renal arteries and moderate stenoses as well as diffuse non-stenosing lesions. CONCLUSION: In comparison with angiography, the diagnostic value of Doppler waveform analysis in the detection of renal artery stenoses has specific limitations. In significant stenoses, however, additional valuable haemodynamic information, useful for PTA, can be obtained by this easy and accessible method.     

Oral antiplatelet efficacy of the platelet GPIIb/IIIa antagonist, DMP754 in non-human primates

Binding kinetic studies with XV459, the active form of DMP754, demonstrated comparable binding kinetics (Kd and Koff) with platelets obtained from either human or baboons which were different from that with platelets obtained from dogs. Therefore, the present study was undertaken to evaluate the antiplatelet efficacy of DMP754 following oral administration in baboons. The dose levels evaluated were 0.1 and 1.0 mg/kg, IV and 0.1, 0.3, 1.0, and 3.0 mg/kg, oral of DMP754. Oral doses of DMP754 resulted in dose- and time-related inhibition of platelet aggregation along with a modest effect on bleeding time prolongation. DMP754 at similar oral doses had 24 hours of antiplatelet effects in baboon as compared to 8-12 hours duration of antiplatelet efficacy in dogs. At maximal antiplatelet doses DMP754 demonstrated no significant effects on platelet count, clinical chemistry or hemodynamic profiles in baboons. These data suggest that DMP754 is a potent orally active antiplatelet agent with extended duration after once a day oral administration in non-human primate.     

Electrophoretic karyotype and in vitro antifungal susceptibility of Cryptococcus neoformans isolates from AIDS patients

Electrophoretic karyotype (EK) was used to type 13 clinical isolates of Cryptococcus neoformans from eight AIDS patients. All of the isolates were also tested for their in vitro susceptibilities to fluconazole, itraconazole, D0870, flucytosine, and amphotericin B by a broth macrodilution technique performed according to the National Committee for Clinical Laboratory Standards recommendations. Although all strains were isolated from a limited geographic area, DNA typing showed a wide genetic variation in this group of patients, yielding seven different patterns. Two patients in whom C. neoformans was isolated in the same time period shared similar EK profiles, suggesting the possibility of cross-infection. In three patients, sequential isolates were evaluated: in two of them, EK analysis showed the persistence of the same genotype throughout the infection, whereas from the third, two isolates of C. neoformans with two different DNA profiles were obtained. Despite the small number of strains considered in this study, our susceptibility data indicate that C. neoformans isolates are very susceptible to the new triazoles.     

Re-expression of the alpha 2 beta 1 integrin abrogates the malignant phenotype of breast carcinoma cells

To assess the role of altered alpha 2 beta 1 integrin expression in breast cancer, we expressed the alpha 2 beta 1 integrin de novo in a poorly differentiated mammary carcinoma that expressed no detectable alpha 2-integrin subunit. Expression of the alpha 2 beta 1 integrin resulted in a dramatic phenotypic alteration from a fibroblastoid, spindle-shaped, non-contact-inhibited, motile, and invasive cell to an epithelioid, polygonal-shaped, contact-inhibited, less motile, and less invasive cell. Although expression of the alpha 2 subunit did not alter adhesion to collagen, it profoundly altered cell spreading. Re-expression of the alpha 2 beta 1 integrin restored the ability to differentiate into gland-like structures in three-dimensional matrices and markedly reduced the in vivo tumorigenicity of the cells. These results indicate that the consequences of diminished alpha 2 beta 1-integrin expression in the development of breast cancer and, presumably, of other epithelial malignancies are increased tumorigenicity and loss of the differentiated epithelial phenotype.     

Short-latency auditory evoked potentials in infants with otitis media

Auditory brain-stem potential findings in 154 healthy infants and infants with different forms of middle-ear pathological conditions (306 ears) were indicative of the inflammatory process influence on the parameters of auditory reception in most cases. The changes in the waves' forms and intraoperative morphological findings in the middle ear were correlated. Objective audiometry allows definite determination of the middle ear trouble which is important in diagnosis of latent otitis in infants who are especially prone to this disease.     

Antitumor activity of 9(R)-dihydrotaxane analogs

A novel reduced taxane, 13-acetyl-9(R)-dihydrobaccatin III (1) has been isolated from Taxus canadensis. The selective C-13 deacetylation of this isolate has allowed for the preparation of a wide variety of 9(R)-dihydrotaxane analogs. In general, this series has shown greater stability and water solubility than the 9-carbonyl series while retaining antimicrotubule and tumor cell cytotoxicity activities relative to taxol. Placement of polar functionalities at the C-7 position results in loss of activity whereas alkylation or acylation of either C-7 or C-9 hydroxyl groups ameliorate the activity.     

Accurate determination of modes in dielectric-loaded cylindricalcavities using a one-dimensional finite element method

A unified approach is presented for calculating the resonant frequencies of all the modes in cylindrical cavities axisymmetrically loaded with dielectrics. In this method, the radial variations of the field components in the resonator are expressed in terms of first-degree finite-element polynomials, whereas the axial variations of the field components are approximated by trigonometric functions. To calculate the resonant frequencies, an H-vector variational formulation is employed and minimized with respect to the coefficients of the expanded field components. Spurious solutions which are inherent in the finite-element technique are effectively eliminated by means of a penalty term included in the variational expression, imposing a divergence-free magnetic field constraint. To show the capability of the method, resonant frequencies of several cylindrical cavities, including those loaded with dielectric rods and dielectric rings, were calculated. A mode chart is presented which can be used for designing certain multimode dielectric-loaded cavity filters. In contrast to other rigorous techniques reported in the literature, the present method is highly efficient when dielectrics are fully extended along the cavity length