Mechanisms of tissue damage resulting from the use of oral water irrigation devices

Oral water irrigation devices (WIDs) are widely used for oral physiotherapy in homes and dental clinics throughout the world. A major area of concern in the use of WIDs has been the possibility of injury to the sulcular epithelium and underlying tissue. There are several documented clinical cases of tissue injury with the use of WIDs. The existing WIDs exert excessive pressures on the sulcular epithelium. Although it is known that the high jet impact pressures exerted by the WIDs cause the tissue damage, the underlying damage mechanisms are poorly understood. The damage to the sulcular epithelium and underlying tissue is mediated through several physiological and micromechanical processes and includes, among others, the following damage mechanisms: pressure-induced, diffusion-mediated, deposition of bacteria and toxins into the underlying tissue, damage to the collagen network integrity in the tissue, damage to the blood and lymphatic microcirculation, especially damage to the anchoring filaments attached to the terminal lymphatic wall, and direct mechanical damage due to abnormal shear forces induced by the jet. All these damage processes could lead to tissue necrosis.     

Molecular analysis of fluoroquinolone-resistant Salmonella Paratyphi A isolate, India

Salmonella enterica serovar Paratyphi A is increasingly a cause of enteric fever. Sequence analysis of an Indian isolate showed a unique strain with high-level resistance to ciprofloxacin associated with double mutations in the DNA gyrase subunit gyrA (Ser83-->Phe and Asp87-->Gly) and a mutation in topoisomerase IV subunit parC (Ser80-->Arg).     

Allele and genotype frequency of MDR1 C3435T in Tamilian population

The allele and genotype frequencies of MDR1 C3435T polymorphism were determined in 185 unrelated healthy Tamilians. The genomic DNA was extracted from peripheral leucocytes using phenol chloroform method and genotyped by PCR-RFLP method. The frequencies of MDR1 C3435 and T3435 alleles in Tamilian population were 0.46 and 0.54 respectively. The distribution of T3435 in this population was found to be greater than Africans and almost similar to Caucasians and Orientals. The distribution of CC, CT and TT genotypes was 0.18, 0.56 and 0.26 respectively. The frequency distribution of the CC genotype was lower in them when compared with Chinese and Africans whereas CT genotype was higher in comparison with all the major ethnic groups.     

Periodic and nonperiodic burst responses of frog (Rana pipiens) retinal ganglion cells

Neural activity of class 3 retinal ganglion cells was recorded in frog optic tectum, using extracellular microelectrodes. The stimuli were rectangular patches of contrast (light-on-dark or dark-on-light), applied within the previously determined receptive fields, for periods ranging from a few milliseconds to several seconds. ON and OFF responses were recorded for as long as 1 s following stimulation. Poststimulus time histograms revealed two types of responses, labeled periodic and nonperiodic bursters. The periodic bursters were characterized by periods of high activity separated by silent or near-silent intervals. The bursts occurred rhythmically with frequencies roughly between 15 and 50 Hz. Nonperiodic bursters generally showed both broad and sharp peaks in activity, but no regular periodicities. Activity profiles were flat initially, with silent periods appearing after the first few stimulus presentations, suggesting an inhibitory nature of the bursting process. The records were shown to combine the activities of several neurons. Analysis of the waveforms in real time made possible isolation of some units. In these cases, neurons exhibited a high degree of selective synchrony, i.e., the sharing of a portion of the activity profile, and notable differences at other times. These data have implications for the processing of visual information.     

NRAMP1 and hGPX1 gene polymorphism and response to bacillus Calmette-Guérin therapy for bladder cancer

Background

The natural resistance-associated macrophage protein 1 (NRAMP1) gene is associated with susceptibility to Mycobacterium tuberculosis in humans and to bacillus Calmette-Guérin (BCG) in mice. The detoxification enzyme, human glutathione peroxidase 1 (hGPX1), is associated with recurrence of bladder cancer (BCa).

Objective

To determine whether NRAMP1 and hGPX1 gene polymorphisms correlate with response to BCG immunotherapy for non–muscle-invasive BCa (NMIBC).

Design, setting, and participants

DNA was obtained from the peripheral blood of 99 NMIBC patients who were prospectively randomized to receive postresection intravesical BCG (81 mg [n = 50] or 27 mg [n = 19]) or BCG (27 mg) with interferon alpha (IFN-α; n = 30). The median follow-up time was 60 mo.

Intervention

Intravesical BCG or BCG–IFN-α.

Measurements

Restriction fragment length polymorphism (RFLP) analysis was performed to identify polymorphisms in the NRAMP1 promoter region (GT repeat number) and at position 543 (aspartate [D] and/or asparagine [N] expression) within the NRAMP1 protein (D543N) and position 198 (proline and/or leucine expression) within the hGPX1 protein (Pro198Leu). Data were analyzed using χ² analysis, multivariate analysis, and Kaplan-Meier curves.

Results and limitations

On univariate analysis, the NRAMP1 D543N G:G genotype had decreased cancer-specific survival (CSS; p = 0.036). The hGPX1 CT genotype (Pro-Leu) had decreased recurrence time (p = 0.03) after BCG therapy. On multivariate analysis, patients with the NRAMP1 D543N G:G genotype and allele 3 (GT)n polymorphism had decreased recurrence time (p = 0.014 and p = 0.03) after BCG therapy. The limitation of this study was its small sample size.

Conclusions

Polymorphisms of the NRAMP1 and hGPX1 genes may be associated with recurrence of BCa after BCG immunotherapy.