Differential effects of inactivated Axin1 and activated beta-catenin mutations in human hepatocellular carcinomas

Perturbations to the Wnt signaling pathway have been implicated in a large proportion of human hepatocellular carcinomas (HCCs). Activating beta-catenin mutations and loss of function mutations in Axin1 are thought to be functionally equivalent. We examined the Wnt pathway in HCC by comparing the expression of beta-catenin target genes and the level of beta-catenin-dependent transcriptional activation, in 45 HCC tumors and four cell lines. Among these samples, beta-catenin and AXIN1 were mutated in 20 and seven cases, respectively. We found a significant correlation between activated beta-catenin mutations and overexpression of mRNA for the target genes glutamine synthetase (GS), G-protein-coupled receptor (GPR)49 and glutamate transporter (GLT)-1 (P=0.0001), but not for the genes ornithine aminotransferase, LECT2, c-myc and cyclin D1. We also showed that GS is a good immunohistochemical marker of beta-catenin activation in HCC. However, we observed no induction of GS, GPR49 or GLT-1 in the five inactivated Axin1 tumors. Beta-catenin-dependent transcriptional activation in two Axin1-mutated HCC cell lines was much weaker than in beta-catenin-mutated cell lines. Our results strongly suggest that in HCC, contrary to expectation, the loss of function of Axin1 is not equivalent to the gain of function of beta-catenin. Our results also suggest that the tumor suppressor function of Axin1 in HCC may be related to another, non-Wnt pathway.

Isolation and serological identification of enteropathogenic Escherichia coli in pasteurized milk in Brazil

OBJECTIVE

To evaluate the microbiological quality of pasteurized milk commercialized in Rio de Janeiro, Brazil, and determine serologically enteropathogenic Escherichia coli (EPEC) strains in E. coli isolates obtained from milk samples.

METHODS

Ninety samples of pasteurized milk - types B and C - of three different commercial brands, purchased in supermarkets and bakeries in Rio de Janeiro, were examined. The amount of total and fecal coliform bacteria was estimated using the Most Probable Number technique. Mesophilic, psychrotrophic, and thermoduric microorganism counts were determined by the Standard Plate Count technique. Isolation and identification of E. coli were carried out using conventional physiological tests. Commercial antisera were used for serological characterization of EPEC.

RESULTS

The three milk brands analyzed revealed bacterial counts above the regulated values of the Brazilian government. It was found that among 208 strains of E. coli isolated, 46 (22.1%) were serologically classified as EPEC. The most common EPEC serogroup was O55 (15.2%).

CONCLUSIONS

Though recent studies on virulence factors indicate that not all strains serologically classified as EPEC are able to attaching/effacing lesion, it is believed that the isolation of EPEC serogroups from pasteurized milk represent a potential risk for children, as well as an indicative of the presence of other enteropathogens.

Estimation of the local synthesis of immunoglobulin G (IgG) in the central nervous system of patients with spinal cord schistosomiasis by the IgG index

By analogy with other infections of the central nervous system (CNS), it is believed that schistosomal myeloradiculopathy (SMR) is an entity that may involve a mild-to-moderate degree of impairment of the blood-brain barrier along with intrathecal synthesis of antibodies. The first of these aspects is obvious but the second has not been clearly demonstrated. This study was undertaken in Brazil with the aim of investigating the production of immunoglobulin G (IgG) within the CNS in patients with SMR, by the determination of the cerebrospinal fluid (CSF) IgG index. The study population included 54 patients with SMR, evaluated prospectively. The CSF IgG index was increased in 43 of them (80%). Preliminary results from our laboratory suggest that these antibodies are reactive against Schistosoma mansoni antigens. Thus, this finding also suggests that this index may be useful in the differential diagnosis of SMR.

Effect of hyperbaric oxygen on the regeneration of experimental crush injuries of nerves

Hyperbaric oxygen has been successfully used on treatment of acute ischemic injuries involving soft tissues and chronic injuries. In nerve crush injuries, the mechanisms involved are very similar to those found in ischemic injuries. Consequently, it is logical to hypothesize that hyperbaric oxygen should improve nerve repair, which is a critical step on functional recovery. In the present study, we created standard nerve crush injuries on sciatic nerves of rats, which underwent treatment with hyperbaric oxygen. Results were assessed by functional evaluation using walking-track analysis. The functional recovery indexes observed did not differ from control group. We concluded that hyperbaric oxygen therapy, in the schedule used, had no influence on functional recovery after nerve crush injuries.

Insulin in w/o/w multiple emulsions: preparation characterization and determination of stability towards proteases in vitro

In this work two w/o/w multiple emulsions composed of soybean oil or medium-chain triglycerides and containing insulin were studied. These emulsions were prepared by means of two-step emulsification procedure. The w/o/w emulsions obtained were stable for at least 6 months of storage at 4-6 degrees C. The yield of encapsulation of insulin was > 95%. The main release mechanism is a swelling-breakdown phenomenon. In vitro, the two w/o/w multiple emulsions were able to protect insulin against enzymatic degradation. These results indicate that multiple emulsions have potential as a carrier of insulin for oral administration.

Insulin in w/o/w multiple emulsions: biological activity after oral administration in normal and diabetic rats

In this work the biological effects of two w/o/w multiple emulsions composed of the soybean oil (EHS) or medium-chain triglycerides (ETCM), containing insulin, were studied. The release mechanism of insulin from multiple emulsions proposed in our previous in-vitro investigations was confirmed by subcutaneous administration. This mechanism is the swelling-breakdown phenomenon which occurs when the emulsions are diluted under hypo-osmotic condition. The biological effect after oral administration, evaluated in two experimental protocols, single administration in normal and diabetic rats and short-term treatment in diabetic rats, shows that in diabetic rats small amounts of biologically active insulin were absorbed from these emulsions. In these experiments no significant difference between EHS and ETCM was found.

The value of an enzyme-linked immunosorbent assay for the diagnosis of schistosomiasis mansoni myeloradiculopathy

The role of serological tests on cerebrospinal fluid (CSF) in the diagnosis of neuroschistosomiasis has not been fully elucidated; the condition is essentially diagnosed on the basis of circumstantial evidence, which may lead to an erroneous diagnosis, especially in highly endemic areas. We therefore carried out a prospective case-control study in which we compared the concentrations of immunoglobulin G (IgG) specific for schistosome soluble egg antigen (SEA) present in the CSF of 54 patients with schistosomiasis mansoni myeloradiculopathy (SMMR) with those observed in a control group consisting of 41 patients with epidemiological and serological evidence of exposure to schistosomes, and with other neurological disorders that result in mild to moderate impairment of the blood-brain barrier. Anti-SEA IgG was estimated by an enzyme-linked immunosorbent assay. The sensitivity, specificity and positive and negative predictive values were 56%, 95%, 94% and 62% respectively. Likelihood ratios and the corresponding post-test probabilities were determined for 4 levels of anti-SEA IgG in CSF. A value below 0.1 micrograms/mL practically excluded the possibility of SMMR (post-test probability < 5%), a value above 1.4 micrograms/mL practically confirmed the diagnosis of SMMR (post-test probability > 96%), values of 0.1 to 0.5 microgram/mL had no diagnostic value (post-test probability approximately 45%), and values of 0.6 to 1.4 micrograms/mL were useful in some situations (post-test probability approximately 70%). We conclude that the estimation of anti-SEA IgG in the CSF is useful for the diagnosis of SMMR.

[Renal dysplasia: clinico-pathologic review]

Histology records from 63 nephrectomies were reviewed; 22 patients had unilateral totally dysplastic kidneys and 5 had polar or segmental dysplasia. A clinicopathological study of these cases was undertaken. In the first group, there was a slight male preponderance and 75% of the patients presented were under two years of age. Urinary tract infection was the most common complaint. 4 patients were diagnosed in utero by ultrasound and 5 infants presented an abdominal mass. Hypertension was documented in a newborn baby. Ipsilateral lower urinary tract anomalies were found in 12 patients and those of the contralateral kidney in 2 children. There were 3 cases of extrarenal anomalies. Histological examination revealed 13 cases of multicystic dysplasia and 9 of solid dysplasia. Metaplastic cartilage was found in 1 case. In the group of segmental dysplasia, age ranging from 27 weeks' gestation to 8 years, at the time of the diagnosis. They all had duplex kidneys and 4 had ureterocele. Histological study in these cases was similar to the one found in the previous series, although superimposed inflammatory changes were more pronounced. Some of the theories regarding the pathogenesis of this disorder are reviewed and the importance of its diagnosis is emphasised.