Androgen receptor YAC transgenic mice carrying CAG 45 alleles show trinucleotide repeat instability

X-linked spinal and bulbar muscular atrophy (SBMA) is caused by a CAG repeat expansion in the first exon of the androgen receptor (AR) gene. Disease-associated alleles (37-66 CAGs) change in length when transmitted from parents to offspring, with a significantly greater tendency to shift size when inherited paternally. As transgenic mice carrying human AR cDNAs with 45 and 66 CAG repeats do not display repeat instability, we attempted to model trinucleotide repeat instability by generating transgenic mice with yeast artificial chromosomes (YACs) carrying AR CAG repeat expansions in their genomic context. Studies of independent lines of AR YAC transgenic mice with CAG 45 alleles reveal intergenerational instability at an overall rate of approximately 10%. We also find that the 45 CAG repeat tracts are significantly more unstable with maternal transmission and as the transmitting mother ages. Of all the CAG/CTG repeat transgenic mice produced to date the AR YAC CAG 45 mice are unstable with the smallest trinucleotide repeat mutations, suggesting that the length threshold for repeat instability in the mouse may be lowered by including the appropriate flanking human DNA sequences. By sequence-tagged site content analysis and long range mapping we determined that one unstable transgenic line has integrated an approximately 70 kb segment of the AR locus due to fragmentation of the AR YAC. Identification of the cis - acting elements that permit CAG tract instability and the trans -acting factors that modulate repeat instability in the AR YAC CAG 45 mice may provide insights into the molecular basis of trinucleotide repeat instability in humans.      

Accuracy of a commercial enzyme-linked immunosorbent assay for CagA in patients from Brazil with and without gastric carcinoma

We validated a commercial enzyme-linked immunosorbent assay for the detection of anti-CagA antibodies in Brazilian patients with Helicobacter pylori infection. The test presented high sensitivity (97.4%) and specificity (88.9%) when employed in patients without gastric carcinoma. However, in gastric carcinoma patients, the test was neither sensitive nor specific enough to detect cagA-positive H. pylori infection.     

Histamine H1- and H2-receptor involvement in eosinophil infiltration and the microvascular changes associated with cutanneous anaphylaxis

Several substances alter eosinophil motility, but the relative importance of these putative mediators in immediate hypersensitivity remains unclear. The present study has reinvestigated the role of histamine in type I allergic eosinophil infiltration, and the temporally associated microvascular events, by examining the effect of H₁-and H₂-receptor antagonist pretreatment. A combination of cimetidine and pyrilamine significantly reduced eosinophil accumulation, whereas neither antagonist alone was effective. Similarly, cutaneous hyperemia, measured indirectly as ear surface temperature, was reduced only by the cimetidine-pyrilamine combination. Pyrilamine partially attenuated the increase in microvascular permeability, but the addition of cimetidine provided no further reduction.It appears that histamine participates significantly in mediating both the microvascular changes and the eosinophil infiltration evoked by cutaneous anaphylaxis. The histaminergic component of increased microvascular permeability appears to be an H₁-receptor mediated phenomenon. However, blockade of both H₁-and H₂-receptor subtypes is required to inhibit the hyperemia and eosinophil infiltration responses.     

Purification of alpha-1-antitrypsin monomer by preparative electrophoresis.

Alfa-1-antitrypsin (alpha 1AT) was purified by pseudoligand chromatography and preparative electrophoresis from the serum of a patient with alpha 1AT deficiency. The combination of the two techniques yielded a high grade batch of alpha 1AT monomer and this was successfully used to purify the protein from the serum of PiMIM1, PiMIM2, and PiZZ phenotype subjects. This procedure should facilitate structural studies of alpha 1AT variants susceptible to intracellular accumulation.     

Hyperpipecolic acidaemia: a diagnostic tool for peroxisomal disorders

Peroxisomal disorders include a complex spectrum of diseases, characterized by a high heterogeneity from both the clinical and the biochemical points of view. Specific assays are required for the study of peroxisome metabolism. Among these, pipecolic acid evaluation is considered as a supplementary test. We have established the diagnostic role of pipecolic acid in 30 patients affected by a peroxisomal defect (5 Zellweger syndromes, 10 Infantile Refsum diseases, 1 neonatal adrenoleukodystrophy, 6 patients affected by a peroxisomal biogenesis disorder with unclassified phenotype, 1 case of rhizomelic chondrodysplasia punctata (RCDP), 2 acyl-CoA oxidase deficiencies, 2 bifunctional enzyme deficiencies, 2 Refsum diseases, and 1 beta-oxidation deficiency). Pipecolic acid was increased in all generalized peroxisomal disorders, while normal pipecolic acid with abnormal very long chain fatty acid concentrations was strong evidence for a single peroxisomal enzyme deficiency. Unexpectedly, hyperpipecolic acidaemia was found also in a child affected by RCDP and in two patients with Refsum disease. In six patients the suggestion of a peroxisomal disorder was raised by the fortuitous finding of a pipecolic acid peak in amino acid chromatography, routinely performed as a general metabolic screening. For all patients, pipecolic acid proved to be a useful parameter in the biochemical classification of peroxisomal disorders.     

Antimicrobial resistance of Salmonella serotypes isolated from slaughter-age pigs and environmental samples

The aim of this study was to determine the antimicrobial resistance patterns of Salmonella strains isolated from slaughter-age pigs and environmental samples collected at modern swine raising facilities in Brazil. Seventeen isolates of six serotypes of Salmonella enterica subsp. enterica were isolated out of 1,026 collected samples: Salmonella Typhimurium (1), Salmonella Agona (5), Salmonella Sandiego (5), Salmonella Rissen (1), Salmonella Senftenberg (4), and Salmonella Javiana (1). Resistance patterns were determined to extended-spectrum penicillin (ampicillin), broad-spectrum cephalosporins (cefotaxime and ceftriaxone), aminoglycosides (streptomycin, neomycin, gentamicin, amikacin, and tobramycin), narrow-spectrum quinolone (nalidixic acid), broad-spectrum quinolone (ciprofloxacin and norfloxacin), tetracycline, trimethoprim, and chloramphenicol. Antimicrobial resistance patterns varied among serotypes, but isolates from a single serotype consistently showed the same resistance profile. All isolates were resistant to tetracycline, streptomycin, and nalidixic acid. One isolate, Salmonella Rissen, was also resistant to cefotaxime and tobramycin. All serotypes were susceptible to ceftriaxone, norfloxacin, ciprofloxacin, ampicillin, gentamicin, and chloramphenicol. The high resistance to tetracycline and streptomycin may be linked to their common use as therapeutic drugs on the tested farms. No relation was seen between nalidixic acid and fluoroquinolone resistance.     

Hypoglycémie hyperinsulinémique persistante du nouveau-né et du nourrisson

Persistent hyperinsulinemic hypoglycaemia of infancy (PHHI) is the most frequent cause of hypoglycaemia in infancy. Clinical presentation is heterogeneous, with variable onset of hypoglycaemia and response to diazoxide, and presence of sporadic or familial forms. Underlying histopathological lesions can be focal or diffuse. Focal lesions are characterised by focal hyperplasia of pancreatic islet-like cells, whereas diffuse lesions implicate the whole pancreas. The distinction between the two forms is important because surgical treatment and genetic counselling are radically different. Focal lesions correspond to somatic defects which are totally cured by limited pancreatic resection, whereas diffuse lesions require a subtotal pancreatectomy exposing to high risk of diabetes mellitus. Diffuse lesions are due to functional abnormalities involving several genes and different transmission forms. Recessively inherited PHHI have been attributed to homozygote mutations for the beta-cell sulfonylurea receptor (SUR1) or the inward-rectifying potassium-channel (Kir6.2) genes. Dominantly inherited PHHI can implicate the glucokinase gene, particularly when PHHI is associated with diabetes, the glutamate dehydrogenase gene when hyperammonaemia is associated, or another locus.     

Determination of vitamin B6 in pharmaceutical formulations by flow injection-solid phase spectrophotometry

In this work, a new solid phase spectrophotometric method in association with flow injection analysis for Vitamin B6 (pyridoxine) determination has been developed with direct measurement of light-absorption in C18 material. In the developed method, successive passage of the complex, previously formed in the flowing stream, and eluent through the flow cell and continuous monitoring of the process provided the analytical information needed to determine pyridoxine. Pharmaceutical samples containing Vitamin B6 were previously dissolved in 0.1 mol l(-1) phosphate buffer solution (pH 7.5) and a sample volume of 235 microl was injected directly into carrier stream consisting of a mixture of methanol and 0.1 mol l(-1) phosphate buffer solution adjusted to pH 7.0 (1+1, v/v). The blue indophenol dye produced from the reaction between pyridoxine and N,N-diethyl-p-phenylenediamine after oxidation by potassium hexacyanoferrate(III) was quantitatively retained on C18 support and the spectrophotometric detection was performed simultaneously at 633 nm. The retained complex was quickly eluted from C18 material with the eluent stream consisting of a mixture of methanol and 0.01 mol l(-1) HCl (6+4, v/v). The results showed that the proposed method is simple, rapid and the analytical response is linear in the concentration range of 0.5-10 and 0.2-4 mg l(-1) using 235 and 860 microl of sample, respectively. The limits of detection are 0.15 and 0.060 mg l(-1) and the R.S.D. are 3.6% (at 2 mg l(-1) level) and 4.0% (at 1 mg l(-1) level) using sample volume of 235 and 860 microl, respectively. The system presented an analytical throughput of 15 determinations per hour when a sample volume of 235 microl was utilized. The procedure was successfully applied to the determination of Vitamin B6 in pharmaceutical formulations containing vitamins of B group and others active principles such as Vitamin C and minerals.     

Caval replacement strategy in pediatric retroperitoneal tumors encasing the vena cava: a single-center experience and review of literature

Background

Complete encasement of the inferior vena cava by retroperitoneal tumors is rare. Although replacement of the vena cava has been considered for various conditions in adults, it is rarely used in children except for challenging resections and as a last chance approach – often aiming more at debulking than cure.