Effect of oral nutritional supplementation on weight loss and percutaneous endoscopic gastrostomy tube rates in patients treated with radiotherapy for oropharyngeal carcinoma.

GOALS: Malnutrition in the head and neck cancer population is a widely recognized factor contributing to negative outcomes. The goal of this study was to determine if providing complimentary oral nutritional supplementation for patients undergoing definitive radiation therapy for oropharyngeal carcinoma reduced weight loss and the need for percutaneous endoscopic gastrostomy (PEG) tube placement. MATERIALS AND METHODS: The data from 79 patients undergoing radiotherapy for oropharyngeal cancer were extracted and analyzed retrospectively from an institutional Human Investigation Committee approved database for the study of advanced radiation therapy techniques for head and neck cancer. Forty patients were treated before the initiation of a nutritional supplementation program, and 39 patients received supplementation. Patients were stratified by type of treatment (radiation alone or chemoradiation) and whether or not they had a PEG tube. RESULTS: All patient groups receiving supplementation manifested a significant decrease in weight loss compared to those who did not receive it. Nutritional supplementation was associated with a 40% relative reduction in weight loss in patients treated with radiotherapy alone (6.1 vs 10.1%, p = 0.008) and a 37% reduction in weight loss in patients treated with chemoradiotherapy (6.7 vs 10.7%, p = 0.007). When patients were stratified by the presence or absence of a PEG tube, both groups experienced a 39% relative reduction in weight loss (with PEG, 5.7 vs 9.3%, p = 0.028; without PEG, 6.9 vs 11.2%, p = 0.002). Supplementation was associated with a decreased need for PEG tube placement (31% decreased to 6%) in patients treated with radiotherapy alone. CONCLUSIONS: Providing complimentary oral nutritional supplementation significantly decreases weight loss and the need for PEG tube placement in patients undergoing radiation therapy for oropharyngeal cancer.

Secondary supratentorial primitive neuroectodermal tumor following irradiation in a patient with low-grade astrocytoma.

We report a case of a supratentorial primitive neuroectodermal tumor (PNET) that occurred 12 years after cranial irradiation for a grade II astrocytoma. Neuroimaging was unable to distinguish between a recurrence of the original neoplasm and the development of a new, distinct entity. Pathologic review assisted by immunohistochemical staining, however, revealed a high-grade PNET. Although rare, PNET needs to be included in the differential diagnoses for previously irradiated patients, who develop recurrent brain tumors in the presence of uncharacteristic imaging features.

Physiological studies of Escherichia coli strain MG1655: growth defects and apparent cross-regulation of gene expression.

Escherichia coli strain MG1655 was chosen for sequencing because the few mutations it carries (ilvG rfb-50 rph-1) were considered innocuous. However, it has a number of growth defects. Internal pyrimidine starvation due to polarity of the rph-1 allele on pyrE was problematic in continuous culture. Moreover, the isolate of MG1655 obtained from the E. coli Genetic Stock Center also carries a large deletion around the fnr (fumarate-nitrate respiration) regulatory gene. Although studies on DNA microarrays revealed apparent cross-regulation of gene expression between galactose and lactose metabolism in the Stock Center isolate of MG1655, this was due to the occurrence of mutations that increased lacY expression and suppressed slow growth on galactose. The explanation for apparent cross-regulation between galactose and N-acetylglucosamine metabolism was similar. By contrast, cross-regulation between lactose and maltose metabolism appeared to be due to generation of internal maltosaccharides in lactose-grown cells and may be physiologically significant. Lactose is of restricted distribution: it is normally found together with maltosaccharides, which are starch degradation products, in the mammalian intestine. Strains designated MG1655 and obtained from other sources differed from the Stock Center isolate and each other in several respects. We confirmed that use of other E. coli strains with MG1655-based DNA microarrays works well, and hence these arrays can be used to study any strain of interest. The responses to nitrogen limitation of two urinary tract isolates and an intestinal commensal strain isolated recently from humans were remarkably similar to those of MG1655.

Aquaporin Z of Escherichia coli: reassessment of its regulation and physiological role.

Transcription of an aqpZ-lac fusion in a single copy on the Escherichia coli chromosome increased as cells entered the stationary growth phase. This was true in a variety of media, and increased transcription in enriched medium required the RpoS sigma factor. Expression of the aqpZ-lac fusion was not affected by up- or downshifts in osmolality. Disruption of aqpZ had no detectable adverse effects.

Ammonium/methylammonium transport (Amt) proteins facilitate diffusion of NH3 bidirectionally.

The ammonium/methylammonium transport (Amt) proteins of enteric bacteria and their homologues, the methylammonium/ammonium permeases of Saccharomyces cerevisiae, are required for fast growth at very low concentrations of the uncharged species NH(3). For example, they are essential at low ammonium (NH(4)+ + NH(3)) concentrations under acidic conditions. Based on growth studies in batch culture, the Amt protein of Salmonella typhimurium (AmtB) cannot concentrate either NH(3) or NH(4)+ and this organism appears to have no means of doing so. We now show that S. typhimurium releases ammonium into the medium when grown on the alternative nitrogen source arginine and that outward diffusion of ammonium is enhanced by the activity of AmtB. The latter result indicates that AmtB acts bidirectionally. We also confirm a prediction that the AmtB protein would be required at pH 7.0 in ammonium-limited continuous culture, i.e., when the concentration of NH(3) is < or =50 nM. Together with our previous studies, current results are in accord with the view that Amt and methylammonium/ammonium permease proteins increase the rate of diffusion of the uncharged species NH(3) across the cytoplasmic membrane. These proteins are examples of protein facilitators for a gas.