Type A behavior pattern and blood glucose control in diabetic children

We studied the relationship between presence of Type A behavior pattern and glycemic response to stress in children with insulin dependent diabetes mellitus (IDDM). Twelve male (six Type A and six Type B) and nine female (four Type A and five Type B) insulin-dependent diabetic patients between the ages of 8 and 16 years received a standard meal and blood glucose values were assessed two hours later. All subjects then played a competitive videogame for 10 minutes following which blood glucose was assessed again. Preprandial and postprandial blood glucose values did not differ between the groups. However, only Type A subjects showed a hyperglycemic response to the videogame stress. Type A subjects also demonstrated significantly higher glycohemoglobin values. In order to assure that this effect was due to a differential response to stress and not simply a difference in metabolic response to a meal, a second study was conducted in which blood glucose values were assessed at one, two and three hours following a standard meal. No significant differences in postprandial blood glucose values were observed between Type A and Type B subjects. These data support previous research which has suggested that some but not all patients with IDDM show a hyperglycemic response to stress.     

Helicobacter pylori possesses two CheY response regulators and a histidine kinase sensor, CheA, which are essential for chemotaxis and colonization of the gastric mucosa

Infection of the mucous layer of the human stomach by Helicobacter pylori requires the bacterium to be motile and presumably chemotactic. Previous studies have shown that fully functional flagella are essential for motility and colonization, but the role of chemotaxis remains unclear. The two-component regulatory system CheA/CheY has been shown to play a major role in chemotaxis in other enteric bacteria. Scrutiny of the 26695 genome sequence suggests that H. pylori has two CheY response regulators: one a separate protein (CheY1) and the other (CheY2) fused to the histidine kinase sensor CheA. Defined deletion mutations were introduced into cheY1, cheY2, and cheA in H. pylori strains N6 and SS1. Video tracking revealed that the wild-type H. pylori strain moves in short runs with frequent direction changes, in contrast to movement of cheY2, cheAY2, and cheAY2 cheY1 mutants, whose motion was more linear. The cheY1 mutant demonstrated a different motility phenotype of rapid tumbling. All mutants had impaired swarming and greatly reduced chemotactic responses to hog gastric mucin. Neither cheY1 nor cheAY2 mutants were able to colonize mice, but they generated a significant antibody response, suggesting that despite impaired chemotaxis, these mutants were able to survive in the stomach long enough to induce an immune response before being removed by gastric flow. Additionally, we demonstrated that cheY1 failed to colonize gnotobiotic piglets. This study demonstrates the importance of the roles of cheY1, cheY2, and cheA in motility and virulence of H. pylori.     

Dehydroascorbate transport in human chondrocytes is regulated by hypoxia and is a physiologically relevant source of ascorbic acid in the joint

OBJECTIVE: To evaluate the dehydroascorbate (DHA) transport mechanisms in human chondrocytes. METHODS: The transport of L-(14)C-DHA in human chondrocytes was analyzed under various conditions, including the use of RNA interference (RNAi), to determine the role of glucose transporter 1 (GLUT-1) and GLUT-3 in L-14C-DHA transport and to evaluate the effects of physiologically relevant oxygen tensions on L-14C-DHA transport. In order to estimate the contributions of reduced ascorbic acid (AA) and DHA to intracellular ascorbic acid (Asc), the quantities of AA and DHA were measured in synovial fluid samples from osteoarthritis (OA) patients and compared with the reported levels in rheumatoid arthritis (RA) patients. RESULTS: DHA transport in human chondrocytes was glucose-sensitive, temperature-dependent, cytochalasin B-inhibitable, modestly stereoselective for L-DHA, and up-regulated by low oxygen tension. Based on the RNAi results, GLUT-1 mediated, at least in part, the uptake of DHA, whereas GLUT-3 had a minimal effect on DHA transport. DHA constituted a mean 8% of the total Asc in the synovial fluid of OA joints, in contrast to 80% of the reported total Asc in RA joints. CONCLUSION: We provide the first evidence that chondrocytes transport DHA via the GLUTs and that this transport mechanism is modestly selective for L-DHA. In the setting of up-regulated DHA transport at low oxygen tensions, DHA would contribute 26% of the total intracellular Asc in OA chondrocytes and 94% of that in RA chondrocytes. These results demonstrate that DHA is a physiologically relevant source of Asc for chondrocytes, particularly in the setting of an inflammatory arthritis, such as RA.     

An evaluation of continuous positive airway pressure (CPAP) therapy in the treatment of hypernasality following traumatic brain injury: a report of 3 cases

OBJECTIVE: To evaluate the effectiveness of continuous positive airway pressure (CPAP) therapy in the treatment of hypernasality following traumatic brain injury (TBI). DESIGN: An A-B-A experimental research design. Assessments were conducted prior to commencement of the program, midway, immediately posttreatment, and 1 month after completion of the CPAP therapy program. PARTICIPANTS: Three adults with dysarthria and moderate to severe hypernasality subsequent to TBI. OUTCOME MEASURES: Perceptual evaluation using the Frenchay Dysarthria Assessment, the Assessment of Intelligibility of Dysarthric Speech, and a speech sample analysis, and instrumental evaluation using the Nasometer. RESULTS: Between assessment periods, varying degrees of improvement in hypernasality and sentence intelligibility were noted. At the 1-month post-CPAP assessment, all 3 participants demonstrated reduced nasalance values, and 2 exhibited increased sentence intelligibility. CONCLUSIONS: CPAP may be a valuable treatment of impaired velopharyngeal function in the TBI population.     

Use of genome level-informed PCR as a new investigational approach for analysis of outbreak-associated Mycobacterium tuberculosis isolates

Mycobacterium tuberculosis strain CH, the index isolate linked to a major tuberculosis outbreak associated with high levels of transmissibility and virulence, was characterized by microarray analysis by use of a PCR product array representative of the genome of M. tuberculosis strain H37Rv. Seven potential genomic deletions were identified in CH, five of which were confirmed by PCR analysis across the predicted deletion points. The panel of five PCRs required to individually interrogate these loci was collectively referred to as the genome level-informed PCR (GLIP) assay. GLIP analysis was performed with CH, 12 other epidemiologically linked isolates, and 43 recent, non-outbreak-associated isolates derived from patients within the local area. All 13 outbreak-linked isolates showed a profile corresponding to the presence of all five deletions. These 13 isolates were also found to share common variable-number tandem repeat and mycobacterial interspersed repetitive unit profiles. None of the 43 non-outbreak-associated isolates exhibited the five-deletion profile. Although three individual deletions were present in upwards of 44% of the non-outbreak-associated isolates, no single-deletion isolates were detected. Interestingly, none of these deletions had been previously recognized, and sequence analysis of the immediate flanking regions in CH failed to identify a likely mechanism of deletion for four of the five loci. The GLIP assay also proved valuable in ongoing surveillance of the outbreak, rapidly identifying a further two outbreak-associated cases months after the initial cluster and, importantly, dismissing a further 12 epidemiologically suspect cases, which allowed the optimum deployment of public health resources.     

Gene expression profile of Mycobacterium tuberculosis in a non-replicating state

Mycobacterium tuberculosis is able to persist in the human host for decades in an apparently dormant state where it is presumed to reside in an hypoxic environment. This can be mimicked by the Wayne culture model in which progressive oxygen depletion causes the bacteria to shift into a non-replicating state. We investigated global gene expression in aerobic (roller), microaerophilic (NRP1) and anaerobic (NRP2) cultures. A number of genes were significantly up-regulated as compared to aerobic culture; 178 in NRP1, 210 in NRP2, 88 in both. The two states showed distinct gene expression profiles, although a number of membrane and transmembrane proteins were induced in both conditions. A number of regulatory proteins were up-regulated in NRP2. Glycine dehydrogenase, nitrate reductase and alpha-crystallin were induced in both stages, as were fatty acid metabolism genes including fadD26 and mas and genes of the DosR regulon. In a comparison with other stress conditions, there were more similarities between anaerobic conditions and carbon starvation or heat shock than between microaerophilic conditions and carbon starvation or heat shock, but as expected microaerophilic and anaerobic conditions showed the most similar profile. Our results indicate that a large number of genes are up-regulated during the shift into the persistent state.