A new test of random walks in heterogeneous environments

Environmental heterogeneities can change animal movement in two different manners. First, they can modify movement characteristics (move lengths or turning angles), in which case the movement remains of the diffusive kind. Second, they can bias displacement towards a particular direction in which case it becomes non-diffusive. We propose in this paper a simple method that only requires computing the mean length of a sample of trajectories in some bounded area to distinguish between these two kinds of movement. We show through simulations that the method allows to detect the presence of heterogeneities that orient animal movement. We apply it to experimental trajectories of Messor sancta ants engaged in corpse aggregation to show that their displacement is oriented at the contact of the formed corpse piles and that their trajectories become non-diffusive.

Constitutive nitric oxide synthases are responsible for the nitric oxide production in the ischemic aged cerebral cortex

Aged brain shows reduced biological plasticity to meet emergency conditions such as ischemia, a process in which nitric oxide (NO) and apoptosis have been shown to play important roles. Using a model of transient global ischemia, we have analyzed the NO system and the p53, bax and bcl-2 response in the cerebral cortex of aged rats. Although immediately after ischemia the NO level is maintained, the reperfusion period increases NO concentrations together with the following: (i) greater bulk-protein nitration mainly due to a 50-kDa immunoreactive band; (ii) an increase in p53 protein; and (iii) an up-regulation of Bax together with a down-regulation of Bcl-2. These results match up with induced endothelial nitric oxide synthase expression immediately after ischemia and in neuronal nitric oxide synthase with the reperfusion. However, inducible nitric oxide synthase was not altered with ischemia/reperfusion. Altogether, these data suggest that NO production in cerebral cortex of aged ischemic animals is due to the constitutive NO synthase isoforms. This response is accompanied by the increased expression of pro-apoptotic proteins.

Upregulation of endothelial nitric oxide synthase maintains nitric oxide production in the cerebellum of thioacetamide cirrhotic rats

This study examines the expression and cellular distribution pattern of nitric oxide synthase (NOS) isoforms, nitrotyrosine-derived complexes, and the nitric oxide (NO) production in the cerebellum of rats with cirrhosis induced by thioacetamide (TAA). The results showed local changes in the tissue distribution pattern of the NOS isoforms and nitrated proteins in the cerebellum of these animals. Particularly, eNOS immunoreactivity in perivascular glial cells of the white matter was detected only in TAA-treated animals. In addition, although neither neuronal NOS (nNOS) nor inducible NOS (iNOS) cerebellar protein levels appeared to be affected, the endothelial NOS (eNOS) isoform significantly increased its expression, and NO production slightly augmented in TAA-treated rats. These NOS/NO changes may contribute differently to the evolution of the hepatic disease either by maintaining the guanosine monophosphate-NO signal transduction pathways and the physiological cerebellar functions or by inducing oxidative stress and cell damage. This model gives rise to the hypothesis that the upregulation of the eNOS maintains the physiological production of NO, while the iNOS is silenced and the nNOS remains unchanged. The differential NOS-distribution and expression pattern may be one of the mechanisms involved to balance cerebellar NO production in order to minimize TAA toxic injury. These data help elucidate the role of the NOS/NO system in the development and progress of hepatic encephalopathy associated with TAA cirrhosis.

Spontaneous rupture of renal leiomyosarcoma in a 45-year-old woman

OBJECTIVES

Leiomyosarcoma is a rare histological subtype of renal sarcomas, accounting for approximately 50-60% of the reported cases. Spontaneous rupture of renal tumor is an uncommon event and the most frequent cause is angiomyolipoma. We report a case of spontaneous rupture of leiomyosarcoma in a 45-year-old woman, presenting with severe left flank pain and perirenal hemorrhage.

METHODS

A 45-year-old caucasian white woman was transferred to our department from emergency room of a different Hospital for acute left flank pain interpreted as a renal colic not responsive to medical therapy. On clinical examination patient was haemodynamically stable but with rapid decrease in hemoglobin, pale, without haematuria with a persistent left flank and hypochondrium pain as in acute abdomen. CT scan of abdomen showed a retroperitoneal haematoma around the left kidney, and a large heterogeneous mass.

RESULTS

Laparotomy was urgently performed. There was large retroperitoneal hematoma extending from left kidney to pelvic space. At the upper pole of the kidney a bleeding tumor was found. Radical nephrectomy was performed. The histological diagnosis was of low-grade leiomyosarcoma from renal angiomyolipoma.

CONCLUSIONS

We attract attention both on kidney cancer (at our knowledge only 3 cases described in literature) and on the need of imaging in the clinical approach of renal colic. We strongly believe that the patients presenting at emergency for renal colic must be scanned by ultrasounds or TC.

Q fever: a new cause of 'doughnut' granulomatous lobular panniculitis

Q fever is an uncommon zoonotic rickettsial disease with no exanthem or specific cutaneous lesions. Only nonspecific cutaneous involvement has been reported to date. A 69-year-old Spanish woman with chronic myelogenous leukaemia developed fever and two subcutaneous nodules. The patient complained of extreme pain. Biopsy revealed a granulomatous lobular panniculitis with a characteristic 'fibrin ring' or 'doughnut' appearance: fibrin and inflammatory cells arranged around a central clear space. Changes of membranous lipodystrophy were also found. Q fever serological studies were positive. Our patient had panniculitis with singular histopathological features. These histopathological changes have been described in liver and bone marrow of patients with Q fever. To the best of our knowledge, this cutaneous involvement due to Q fever has not previously been described in the literature.

Synthesis of alkyl-alpha-L-rhamnosides by water soluble alcohols enzymatic glycosylation

The synthesis of alkyl-alpha-rhamnosides by alpha-rhamnosidase was studied using rhamnose and rhamnosides, particularly the flavonoid naringin, as glycosylation agents, and water soluble alcohols as acceptors. The reaction products were analyzed by HPLC chromatography and identified by 13C y 1H NMR. The glycosylation of alcohols by reverse hydrolysis was maximum for 40% methanol, 30% ethanol, 10% propanol and 20% isopropanol. Under optimum conditions the yield of rhamnose to alkyl-alpha-rhamnoside transformation decreased from 68% for methyl-alpha-rhamnoside to 10% for isopropyl-alpha-rhamnoside. The time course of rhamnosylations produced using naringin as the donor was comparable with that of the reverse hydrolysis obtained at the same molar concentration of the donor. The flavonoids and their derivatives remaining in the solution after the glycosylation were removed by ion exchange QEAE chromatography at pH 10. These results indicate that both, reverse hydrolysis and glycosylation by naringin are acceptable procedures for the enzymatic synthesis of short chain length alkyl-alpha-L-rhamnosides.

[Hepatitis C virus variability and interferon-mediated pathway inhibition]

The most important aim of this study was to describe the hypothetical relationship between the PePHD region variability (related to the synthesis of a cellular enzyme pseudosubstrate) of the hepatitis C virus and the response of patients to interferon therapy. This interaction could be a determining factor in the antiviral effect of interferon. All samples (from 24 patients with chronic hepatitis C infection) were analyzed using a previously described method based on RT-PCR and nested PCR mediated by single-strand conformation polymorphism assay (SSCP). The patients were divided into three groups with respect to the response to therapy: 8 patients with sustained response, 8 patients with transient response and 8 nonresponders. In all samples a low genetic heterogeneity pattern was detected, which was independent of other factors involved in the lack of response to treatment, such as age, sex or viral genotype. This genetic homogeneity is an indirect indication of the importance of the region on viral persistence. However, more studies are needed to evaluate the real role of this sequence on the interaction between cells and the virus.

Utility of an in-house mycobacteriophage-based assay for rapid detection of rifampin resistance in Mycobacterium tuberculosis clinical isolates

A rapid in-house mycobacteriophage-based assay to identify multidrug resistance by detecting the rifampin susceptibility of Mycobacterium tuberculosis in a microtiter plate format was evaluated. The sensitivity, specificity, and overall accuracy of the assay were 100%. This test is rapid to perform and suitable for widespread implementation.

Usefulness of urinary antigen detection by an immunochromatographic test for diagnosis of pneumococcal pneumonia in children

We evaluated an immunochromatographic assay detecting pneumococcal antigen in urine samples from children diagnosed with pneumococcal pneumonia. The sensitivity and specificity of the immunochromatographic test with nonconcentrated urine (NCU) were 86.7 and 62.9%, respectively; with concentrated urine (CU), they were 100 and 11.7%, respectively. Pneumococcal antigen was also detected in 42.5% of NCU and 87.1% of CU samples from nasopharyngeal carriers. This is a nonspecific test for the diagnosis of pneumococcal pneumonia in children, particularly the very young.

[Viral quasispecies and their implications in antiviral therapy]

The aim of this study was to evaluate the relationship between the quasispecies in the HVR1 region of the hepatitis C virus and treatment evolution in order to determine whether genetic complexity is predictive of response to interferon therapy. The samples were analyzed by nested RT-PCR-mediated single-strand conformation polymorphism assay (SSCP). Twelve patients with chronic hepatitis C were studied and divided into three groups: three patients with sustained response, three patients with transient response and six nonresponders. The patients in the sustained response group showed a low genetic complexity pattern. By contrast, in three nonresponders and in one patient with transient response, the SSCP assay revealed a high complexity pattern. With regard to the remaining patients with transient response, new SSCP bands appeared, thereby modifying their genetic complexity pattern. Therefore, nonresponse to interferon treatment could be related to the presence of a high genetic complexity pattern, while the detection of a low genetic complexity pattern is necessary for a positive response to interferon therapy. Due to the limited number of patients involved in this study, it was not possible to predict the response to interferon based on the genetic complexity pattern. Larger studies are therefore required.

Assessment of a new test to detect Legionella urinary antigen for the diagnosis of Legionnaires' Disease

Given that the rate of mortality by Legionella pneumonia increases in incorrectly treated patients, rapid diagnosis and early antibiotic treatment are needed. We have assessed the performance of a new enzyme immunoassay (EIA) test (Bartels Inc. Trinity Biotech Company, Wicklow, Ireland) to detect Legionella pneumophila antigen in urine comparing it to Binax EIA (Binax, Portland, Maine). We also evaluated the capability of both EIAs to detect extracted soluble antigens of Legionella strains. Using nonconcentrated urine samples (NCU) the sensitivity of Bartels EIA was 74.1% (66/89) and the sensitivity of Binax EIA was 51.7% (46/89). The sensitivity of both EIA tests were 91.5% (54/59) using concentrated urine samples (CU). Specificity of both EIA tests was 100% in NCU and CU. Bartels EIA was able to detect all serogroup L. pneumophila antigens, achieving a higher sensitivity in the case of L. pneumophila serogroup 1 soluble antigen. The new EIA was found to be a useful test for the rapid diagnosis of Legionella pneumonia, being a better alternative to the Binax EIA if NCU is used.

Immunohistochemical localisation of neuronal nitric oxide synthase in the rainbow trout kidney

The distribution of nitrergic nervous structures in the trout kidney was studied by peroxidase-linked ABC immunostaining procedures using a polyclonal antibody raised against the neuronal isoform of nitric oxide synthase. The nitrergic plexus reaches the kidney along the vasculature, mainly running with the postcardinal vein where nitrergic fibres, microganglia like cellular clusters and isolated neurones were detected. The atubular head-kidney only showed isolated nitrergic fibres close to the larger arteries. On the other hand, the collecting tubules, collecting ducts, large arteries and glomerular arterioles of the tubular middle and posterior trunks were innervated by nitrergic fibres even though immunoreactive neurones were also observed in close apposition to some tubular elements and large arteries. These results suggest that, according to morphofunctional differences between the fish and mammalian kidneys, nitrergic neural structures may be involved in the control of particular renal functions in the rainbow trout.