Effect of atrial natriuretic factor and cyclic guanosine monophosphate on water and urea transport in the inner medullary collecting duct

We examined the action of high (2×10^–8M) and low (6×10^–9M) concentrations of atrial natriuretic factor (ANF) on water and urea transport in the rat inner medullary collecting duct (IMCD) using the in vitro microperfusion technique. We measured the hydraulic conductivity (Lp ×10^–6 cm/atm per second) and both lumen-to-bath (P _u(lb)) and bath-to-lumen (P _u(bl)) ¹⁴C-urea permeabilities (P _u× 10^–5 cm/s) in the absence and in the presence of vasopressin (VP). High concentrations of ANF were able to inhibit the maximum activity of (50 U/ml) VP-stimulated L _p but physiological concentration of ANF inhibit only submaximum activity (10 U/ml) of VP-stimulated L _p. The hydrosmotic effect of dibutyryl-cyclic 3,5 adenosine monophosphate (cAMP) (10^–4M) was unchanged by high concentrations of ANF (2×10^–8M). Also we found that high (10^–4M) and low (10^–6M) concentrations of exogenous cyclic 3,5-guanosine monophosphate (GMP) while unable to change the Lp in the absence of VP, decreased the maximum activity of VP-stimulated Lp significantly. We also found that ANF inhibits partially and in a reversible manner the VP-stimulated P _u(lb) but not the VP-stimulated P _u(bl). These results demonstrated that plasma concentrations of ANF observed during volume expansion (10^–10M) are able to inhibit submaximum activity of VP-stimulated (10 U/ml) L _p in the rat IMCD, this effect seems to occur before cAMP formation and it appears to be mediated by cGMP. ANF (6× 10^–9M) also reduced the VP-stimulated urea outflux. Therefore, the increase in water excretion produced by ANF could be explained, at least in part, by the inhibition by ANF of vasopressin effects on water and urea transport in the IMCD.This study was presented in part at the VI Latin American Congress of Nephrology, Brazil, October 1985 and at the X^th International Congress of Nephrology, London, July 1987.     

Modulation of acute visceral nociception and bladder inflammation by plant triterpene, α, β-amyrin in a mouse model of cystitis: role of tachykinin NK<Subscript>1</Subscript>-receptors,and K<Superscript>+</Superscript><Subscript>ATP</Subscript> channels

Objective and design: We previously described the visceral antinociceptive property of α, β-amyrin in a mouse model of cystitis induced by cyclophosphamide (CPM). This study examined the contribution of vanilloid-1 (TRPV1), peripheral NK1 receptors to CPM-evoked nociceptive behaviors and bladder edema, and its possible modulation by α, β-amyrin. Methods: The effect of α, β-amyrin (10, 30, and 100 mg/kg, p. o.) and N-acetylcysteine (NAC) on CPM (400 mg/kg, i. p.)-induced cystitis was studied in mice. Sensory deafferentation was done by a high dose capsaicin. The parameters analysed were: CPM-evoked noxious behaviors, bladder edema, vascular permeability, and NK₁ immunoreactivity. To assess the role of K⁺ _ATP channels in α, β-amyrin effect, animals were pretreated with glibenclamide. Results: α, β-amyrin (30 and 100 mg/kg) and NAC significantly (p < 0.01) suppressed the visceral pain-related behaviors and NK₁ immunoreactivity, but bladder edema was reduced weakly. Glibenclamide reversed the effects of α, β-amyrin. Sensory deafferentation by capsaicin significantly reduced the nociceptive responses and the NK₁ immunoreactivity to noxious stimulation by CPM. Conclusions: α, β-amyrin attenuates CPM-induced visceral pain and bladder edema by mechanisms that involve, at least in part, a block either of Substance P release or its receptor function, and partly by opening K⁺ _ATP channels. Received 13 February 2007; returned for revision 13 April 2007; accepted by G. Geisslinger 14 May 2007     

Genetic diversity among clinical isolates of Candida glabrata analyzed by randomly amplified polymorphic DNA and multilocus enzyme electrophoresis analyses

The genetic diversity of 47 clinical and reference strains of Candida glabrata from several geographical origins and diverse clinical disorders, with different antifungal susceptibilities, as well as their genetic relationships were studied through multilocus enzyme electrophoresis (MLEE) and randomly amplified polymorphic DNA (RAPD) techniques. The genetic diversity estimated for 11 MLEE loci measured as average heterozygosity (h) was 0.055. A high level of genetic relatedness among isolates was established by cluster analysis. Forty-nine RAPD markers were analyzed, and the average genetic diversity among isolates, estimated by Shannon's index (Ho), was 0.372. The PhiST values estimated through an analysis of molecular variance to assess genetic differentiation among isolates revealed no genetic differentiation among them. Our results revealed very low genetic diversity among isolates, a lack of differentiation, and no association with their geographic origin and the clinical characteristics.     

Expression of proinflammatory cytokines by hepatic macrophages in acute classical swine fever

Fourteen pigs were inoculated with the 'Alfort 187' strain of classical swine fever (CSF) virus and killed in pairs at 2, 4, 7, 9, 11, 14 or 17 days post-inoculation for histopathological, ultrastructural and immunohistochemical examination. For the latter method, the antibodies used were those against viral antigen Gp55, porcine myeloid marker SWC3, IL-1alpha, IL-6, TNF-alpha and Factor VIII-related antigen. Activation and increase in the number of hepatic macrophages was observed following viral detection in liver, as well as an increase in IL-1alpha and IL-6 production, mainly by Kupffer cells. Maximum detection of viral antigen was observed in the middle stage of the experiment coinciding with overexpression of the three cytokines studied, with IL-6 production by interstitial macrophages prominent at the end. Additionally, the labelling of platelets for Factor VIII-related antigen and the ultrastructural study of the sinusoids revealed activation and aggregation of thrombocytes close to Kupffer cells at the beginning of the infection. The liver seems to play a prominent role in the origin of the thrombocytopenia that occurs in CSF and contributes to the overexpression of proinflammatory cytokines considered responsible for the disorders observed during the course of the disease.     

Systemic infections in three infants due to a lactose-fermenting strain ofSalmonella virchow

Three previously healthy children developed gastroenteritis which led within a few days to systemic infections, two cases of bacteremia and one of meningitis. A lactose-fermentingSalmonella virchow strain was isolated from cerebrospinal fluid and blood cultures. In one case, this strain was also isolated from stool cultures. All the children had been fed the same milk formula. There was no other relationship between them. The batch of dried-milk formula was confirmed as the source of the infection by isolation of an identical lactose-fermentingSalmonella virchow strain by the Centro Nacional de Alimentación.     

Vaccinia virus recombinants as a model system to analyze interferon-induced pathways.

The interferons (IFNs) are a family of cytokines with broad antiviral activities that also control cell proliferation and modulate immune responses. IFNs exert their pleiotropic actions through the regulation of multiple pathways that have been subjected to extensive study using diverse approaches. The scope of this review is to show how we can take advantage of vaccinia virus (VV) to study IFN-related pathways. We summarize and present the different VV models available for studying IFN function and the possibilities that they offer to analyze IFN-induced pathways, IFN modulators, and the biologic effects at the molecular and cellular levels. Emphasis is given to studies of dsRNA-activated signaling with VV lacking E3L (VV DeltaE3L) and in RNA-activated protein kinase (PKR)-related pathways, through the use of VV recombinants (VVr) with inducible PKR (VV PKR). The latest system is versatile, as expression of PKR can be regulated and induced at different times; similarly, VVr can be generated expressing other PKR modulators. As an example of the utility of VVr, we describe how this model has been used to analyze the antiviral and proapoptotic functions of PKR, the impact of PKR on translation, and the PKR-induced activation of the nuclear factor-kappaB (NF-kappaB) pathway.     

The histopathology of pediatric celiac disease: order must prevail out of chaos

The role of histopathology for diagnosing celiac disease (CD) has been recently challenged. However, based in our experience with roughly 4,600 distal duodenal and jejunal biopsies in children it is apparent that appropriate biopsy site, handling, processing, and microscopic evaluation result in a consistent pattern of microscopic changes which allows strong clinical-pathologic correlation. A simple way for establishing the villous/crypt (V/C) ratio is proposed. Normal mucosa displays a V/C ratio of 2.5 or more. Villous atrophy is then graded according to the V/C ratio as follows: Grade 1: 2.5-2; Grade 2: 1-2; Grade 3: 1-0.5, and Grade 4: less than 0.5. The grading should be done in areas of the biopsy where at least 2 to 3 crypts are present in almost its full length. CD disease was consistently associated with villous atrophy grades 3 and 4, which fully recovered or maintained Grade 1 after gluten-free diet. Grade 2 biopsies were rare and related to incomplete gluten-free diet. Patchy lesions were never seen as were patients with normal biopsies later developing mucosal atrophy. Histopathologic evaluation of mucosal biopsies to rule out CD requires adequate biopsy site (distal duodenum or proximal jejunum), and proper handling (oriented material), processing (cutting on edge) and interpretation. The proposed villous atrophy grading may help to adequately compare experiences from different centers as well as to reconcile apparent different findings in separate biopsies. In children histopathology keeps on having a central role for CD diagnosis.