Comparison of phenotypic and genotypic methods for pyrazinamide susceptibility testing with Mycobacterium tuberculosis

Mycobacterium tuberculosis converts pyrazinamide to its active form by using the enzyme pyrazinamidase. This enzyme is coded for on the pncA gene, and mutations in the pncA gene result in absence of active enzyme, conferring resistance to the drug pyrazinamide. We investigated 27 strains of Mycobacterium tuberculosis suspected of being multidrug resistant. Each isolate was tested for susceptibility to pyrazinamide by the BACTEC 460TB method, and 19 were pyrazinamide resistant. The presence of active pyrazinamidase enzyme was sought by using the Wayne assay, which was positive in all of the sensitive isolates and four of the resistant isolates. The pncA gene was amplified by PCR, and mutations were sought by single-strand conformation polymorphism (SSCP) analysis. We identified four isolates which were phenotypically resistant to pyrazinamide, but which had active pyrazinamide enzyme on the Wayne assay and normal pncA gene SSCP. MICs measured by BACTEC 460TB and susceptibility testing at a lower pH of 5.5 confirmed genuine resistance. The pncA gene was sequenced in these four isolates and found not to have any mutations. This implies that an alternative mechanism of resistance exists in these strains. We conclude that genotypic assessment of pyrazinamide resistance is unreliable, because it depends on the identification of a single resistance mechanism. Phenotypic methods such as the BACTEC 460TB technique remain the best methods for pyrazinamide susceptibility testing.     

Fos expression in feeding-related brain areas following intracerebroventricular administration of orphanin FQ in rats

While the influence of orphanin FQ (OFQ) on the regulation of food intake has been substantiated, little is known about feeding-related brain regions that mediate OFQ-induced feeding. To further investigate this, we injected OFQ intracerebroventricularly and evaluated c-Fos immunoreactivity in brain areas thought to be involved in the regulation of food intake. Altered c-Fos expression as a consequence of OFQ injection was observed in the nucleus of the solitary tract, paraventricular nucleus of the hypothalamus, supraoptic nucleus, central nucleus of amygdala, lateral septal nucleus and lateral habenular nucleus. Presumably, OFQ modulates food ingestion through its action on these brain regions, most probably by activating feeding signals as well as suppressing satiety mechanisms.     

Poliomyelitis-like illness after acute asthma

Two children had pain in one arm, followed by weakness and wasting, after an acute exacerbation of bronchial asthma. Similar cases in which a poliomyelitis-like illness was associated with acute asthma have been reported, but the relationship between the two remains conjectural.     

Intravascular local gene transfer mediated by protein- coated metallic stent

Objective To assess the feasibility, efficiency and selectivity of adenovirus- mediated ge ne transfer to local arterial wall by protein- coated metallic stent. Methods A replication- defective recombinant adenovirus carrying the Lac Z reporter gene for nuclear- specific β- galactosidase (Ad- βgal) was used in this study. Th e coating for metallic stent was made by immersing it in a gelatin solution cont aining crosslinker. The coated stents were mounted on a 4. 0 or3. 0mmpe rcutaneous transluminal coronary angioplasty (PTCA) balloon and submersed into a high- titer Ad- βgal viral stock (2×10(10)pfu/ml) for 3 min, and then im planted into the carotid arteries in 4 mini- swines and into the left anterior d escending branch of the coronary artery in 2 mini- swines via 8F large lumen gui ding catheters. The animals were sacrificed7 (n=4), 14 (n=1) and 21 (n=1) days after implantation, respectively. The β- galactosidase expression was as sessed by X- gal staining. Results The results showed that the expression of transgene was detected in all animal. In 1 of carotid artery with an intact intima, the β- gal expression was l imited to endothelial cells. In vessels with denuded endothelium, gene expressi on was found in the sub- intima, media and adventitia. The transfection efficie ncy of medial smooth muscle cells was 38. 6%. In 2 animals sacrificed 7 days af ter transfection, a microscopic examination of X- gal- stained samples did not s how evidence oftransfection in remote organs and arterial segments adjacent to the treated arterial site.Conclusions Adenovirus- mediated arterial gene transfer to endothelial, smooth muscle cells and adventitia by protein- coated metallic stent is feasible. The transfection efficiency is higher. The coated stent may act as a good carrier of adenovirus - mediated gene transfer and have a potential to prevent restenosis following PT CA.     

Obesity and aging.

This review focuses on studies that pertain to obesity and aging. The prevalence of obesity in the elderly is discussed, with an emphasis on body-fat distribution as it relates to morbidity and mortality rates. Treatment options, such as physical activity, growth hormones, and drug therapy, are briefly mentioned. A section that covers some of the most recent issues pertaining to the neuroregulation of feeding and energy expenditure is included. Finally, we briefly discuss anorexia in the aged.     

The Caries Management System: an evidence‐based preventive strategy for dental practitioners. Application for children and adolescents

The application of the Caries Management System (CMS) for children and adolescents follows the rationale underlying the application of the CMS for adults. Briefly, the CMS is a 10‐step, risk‐based, non‐invasive strategy to arrest and remineralize early lesions and to enhance caries primary prevention. The method for assessing each patient’s diet, plaque distribution, and signs of caries as shown in bitewing radiograph images, follows the protocols for adults. Protocols presented here relating to caries risk assessment, lesion diagnosis and management, and patient recall are specific for children and adolescents. Fundamentally, non‐cavitated lesions in primary and especially permanent teeth are managed: (1) professionally by preservative non‐invasive means, including fluoride varnish and sealants; and (2) daily home toothbrushing using fluoride toothpaste where the aim is to arrest lesion progression so that restorations will not be necessary. Monitoring of lesions through the review of clinical signs and bitewing images is the means for assessing caries activity. For those who fail to respond to advice to reduce cariogenic exposures and continue to develop new lesions at a steady or increased rate, a more intensified programme is required; their higher risk status is confirmed and treatment follows the corresponding protocol.