Directly monitor protein rearrangement on a nanosecond-to-millisecond time-scale.

In order to directly observe the refolding kinetics from a partially misfolded state to a native state in the bottom of the protein-folding funnel, we used a "caging" strategy to trap the ß-sheet structure of ubiquitin in a misfolded conformation. We used molecular dynamics simulation to generate the cage-induced, misfolded structure and compared the structure of the misfolded ubiquitin with native ubiquitin. Using laser flash irradiation, the cage can be cleaved from the misfolded structure within one nanosecond, and we monitored the refolding kinetics of ubiquitin from this misfolded state to the native state by photoacoustic calorimetry and photothermal beam deflection techniques on nanosecond to millisecond timescales. Our results showed two refolding events in this refolding process. The fast event is shorter than 20 ns and corresponds to the instant collapse of ubiquitin upon cage release initiated by laser irradiation. The slow event is ~60 µs, derived from a structural rearrangement in ß-sheet refolding. The event lasts 10 times longer than the timescale of ß-hairpin formation for short peptides as monitored by temperature jump, suggesting that rearrangement of a ß-sheet structure from a misfolded state to its native state requires more time than ab initio folding of a ß-sheet.

Thioflavin T and its photoirradiative derivatives: exploring their spectroscopic properties in the absence and presence of amyloid fibrils.

In this work, we found that, during storage or after UV irradiation, ThT is demethylated or oxidized, forming three derivatives. These three derivatives were purified by high performance liquid chromatography and characterized by mass and nuclear magnetic resonance spectroscopy and the spectroscopic properties of pure ThT and the derivatives carefully compared. Our results show that the emission peak at 450 nm results from oxidized ThT and not from the monomeric form of ThT, as previously proposed. The partial conversion of ThT into oxidized and demethylated derivatives has an effect on amyloid detection using ThT assay. Irradiated ThT has the same lag time as pure ThT in the amyloidogenesis of insulin, but the intensity of the emitted fluorescence is significantly decreased.

Correlates of physical activity level among hemodialysis patients in Selangor, Malaysia.

INTRODUCTION: There is mounting evidence demonstrating the importance of adequate physical activity to promote better well-being among hemodialysis patients. Available data pertaining to the levels of physical activity and its determinants among hemodialysis patients is, however, scarce in Malaysia. The objectives of this study are hence to determine the levels of physical activity and it associated factors among hemodialysis patients. METHODOLOGY: A total of 70 subjects were recruited from three dialysis centres in Selangor. A face-to-face interview was conducted to obtain socio-demographic data and subjects' knowledge on dietary sources. Medical history, biochemical parameters and weight status were obtained from medical records. Physical activity level (PAL) was assessed using the Global Physical Activity Questionnaire (GPAQ). RESULTS: A total of 81.4% and 18.6% of the respondents had low and moderate PALs, respectively. Thus, none of the respondents had high PAL. Serum creatinine, education level, personal income and knowledge score on potassium-related medical complications were factors found to correlate significantly with PAL. Multiple linear regression analysis showed that higher PAL was predicted by a lower knowledge score on dietary sodium source, higher education and higher serum creatinine. CONCLUSION: Despite consistent documentation of the potential positive impact of physical exercise on hemodialysis outcomes, the level of physical activity remains low among these patients. It is hoped that these findings can add to the existing body of knowledge and serve as a supporting document for the formulation of appropriate interventions to improve the status of physical activity among hemodialysis patients in Malaysia.

Investigation of the binding preference of reovirus sigma1 for junctional adhesion molecule A by classical and steered molecular dynamics.

Biochemical studies have determined that reoviruses attach to cells by combining attachment protein sigma1 to the binding interface of its receptor protein junctional adhesion molecule A (JAM-A), and the interface normally takes care of the homodimerization of JAM-A. Tighter binding and slower dissociation of for the sigma1-JAM complex than for the JAM-JAM complex have been probed by both biological and atomic force microscopy experiments; however, the mechanism of the binding preference of the attachment protein for JAM-A still remains unclear. With the help of classical and steered molecular dynamics and energy calculations, the unbinding forces and kinetic properties of the complexes are investigated, together with detailed structural information analyses. A multireceptor mechanism is proposed for the binding preference, which can be helpful for future viral infection and vector targeting studies.

Repetitive lumbar punctures as treatment for normal pressure hydrocephalus.

Selected normal pressure hydrocephalus (NPH) patients cannot be treated by shunt operation because of the procedure's high complication rate. We have treated cases in which prolonged clinical improvement of NPH was experienced after one or two lumbar punctures (LPs). We evaluated the predictors of prolonged improvement of NPH symptoms by repeated LP. Thirty-one NPH patients were retrospectively evaluated (age 72.5 +/- 5.8 years). Gait disturbance, urinary incontinence, and cognitive impairment were semiquantified. We divided the patients into three groups (non-responders, temporary responders, and prolonged responders) according to their responses after LP. We analyzed the characteristics of the groups. Gait disturbance (p = 0.046) and urinary incontinence (p = 0.040) scores and total NPH symptom score (p = 0.007) after cerebrospinal fluid drainage were more significantly improved in prolonged responders than in temporary responders. On multiple logistic regression analyses, total NPH score improvement was the only predictor of the prolonged responders (p = 0.03, odds ratio 0.148). Our study showed that some NPH patients could maintain favorable courses for at least 1 year after LP without shunt operation. Repeated LP could be an alternative treatment in selected NPH patients.

Excited-state backbone twisting of polyfluorene as detected from photothermal after-effects.

By means of time-resolved photoluminescence and photothermal techniques, after-effects from excited-state dynamics, energy migration, and conformational rearrangement of poly(9,9-di-n-octyl-2,7-fluorene) (PFO) and its homologues has been examined and interpreted with rotational potential maps from quantum mechanical calculations. Steady-state photoluminescence spectral changes and time-resolved photoluminescence measurements of oligofluorenes and PFO diluted in toluene suggest excited state ring torsion occurring within 30 ps of photoexitation. With all effects from internal conversion/intersystem crossing processes properly accounted for, we show that the conformational changes associated with this twisting motion can be quantitatively probed by means of photothermal methods. Results suggest mean torsion between neighboring fluorene units by ca. 40 degrees upon excitation, in agreement with the shift of rotational potential minimum from +/-40 degrees (and +/-140 degrees) in the ground state to +/-20 degrees (and +/-160 degrees) in the first excited singlet state according to results of quantum mechanical calculations.

Bulbar signs in normal population.

BACKGROUND AND OBJECTIVES: There is lack of published data on bulbar signs among the healthy population. This study aims to determine the range of normality of bulbar signs particularly among the elderly. METHODS: Systemic examination of bulbar signs was carried out according to a predetermined protocol on a cohort of young and elderly healthy subjects. RESULTS: A total of 206 subjects were recruited in the study, 104 young adults with mean age of 20 years, and 102 elderly with mean age of 73 years. Uvula deviation was seen in 28 (26.9%) young subjects and 22 (21.6%) elderly. Irregular tongue border was seen in 17 subjects, unilateral in 4 subjects. Fourteen (6.8%) subjects had deviation on tongue protrusion. Occasional tremor of tongue on protrusion is common in both young and old. Persistent (severe) tongue tremor on protrusion was seen in 18.6% of the elderly, and 4.8% of the young. None of the subjects had tremor of tongue at rest. In gag reflex, absence of gagging response was common in elderly, seen in two thirds of the subjects on stimulation of the posterior pharyngeal wall. However, all the subjects had uvular movement. Habituation or suppression of gagging response was seen in close to 90% of young males. CONCLUSION: There is wide range of normality in bulbar signs in normal population, particularly among the elderly.

Mechanistic insights into the physiological functions of cell adhesion proteins using single molecule force spectroscopy.

Intercellular adhesion molecules play an important role in regulating several cellular processes such as a proliferation, migration and differentiation. They also play an important role in regulating solute diffusion across monolayers of cells. The adhesion characteristics of several intercellular adhesion molecules have been studied using various biochemical assays. However, the advent of single molecule force spectroscopy as a powerful tool to analyze the kinetics and strength of protein interactions has provided us with an opportunity to investigate these interactions at the level of a single molecule. The study of interactions involving intercellular adhesion molecules has gained importance because of the fact that qualitative and quantitative changes in these proteins are associated with several disease processes. In this review, we focus on the basic principles, data acquisition and analysis in single molecule force spectroscopy experiments. Furthermore, we discuss the correlation between results obtained using single molecule force experiments and the physiological functions of the proteins in the context of intercellular adhesion molecules. Finally, we summarize some of the diseases associated with changes in intercellular adhesion molecules.

CT planning for breast cancer.

Radiotherapy to the affected breast or chest wall is well established as an integral part of postoperative management of breast cancer. However, it is known to be associated with increased cardiac and pulmonary morbidities and mortalities. Modern technologies, such as CT planning, have shown to improve treatment planning by accurately delivering optimal doses to the target volumes, while minimizing doses to sensitive structures, thus reducing potential treatment-related adverse effects. The purpose of this study is to report on our experiences with CT planning of adjuvant radiotherapy for breast cancer.

Biophysical approaches for studying the integrity and function of tight junctions.

Cell-cell adhesion is an extremely important phenomenon as it influences several biologically important processes such as inflammation, cell migration, proliferation, differentiation and even cancer metastasis. Furthermore, proteins involved in cell-cell adhesion are also important from the perspective of facilitating better drug delivery across epithelia. The adhesion forces imparted by proteins involved in cell-cell adhesion have been the focus of research for sometime. However, with the advent of nanotechnological techniques such as the atomic force microscopy (AFM), we can now quantitatively probe these adhesion forces not only at the cellular but also molecular level. Here, we review the structure and function of tight junction proteins, highlighting some mechanistic studies performed to quantify the adhesion occurring between these proteins and where possible their association with human diseases. In particular, we will highlight two important experimental techniques, namely the micropipette step pressure technique and the AFM that allow us to quantify these adhesion forces at both the cellular and molecular levels, respectively.

Light and scanning electron microscopic evaluation of Glyde File Prep in smear layer removal.

AIM: To evaluate the effectiveness of Glyde File Prep used in conjunction with sodium hypochlorite irrigation in the removal of smear layer produced during root canal instrumentation. METHODOLOGY: Thirty-nine extracted human teeth with single root canals were used. Access cavities were prepared and the teeth divided into three groups of 13 teeth each. Each group was treated by one of the three different regimes of irrigation and conditioning during root canal instrumentation. Group A: 0.5 mL of 1% NaOCl irrigation after each file size with an additional final irrigation of 10 mL 1% NaOCl; group B: 0.5 mL of 1% NaOCl irrigation after each file size with an additional final irrigation of 10 mL 17% EDTA; group C: Glyde File Prep coated on each instrumentation file used in conjunction with 0.5 mL 1% NaOCl irrigation after each file size and an additional final irrigation of 10 mL 1% NaOCl. The teeth were then longitudinally grooved and sectioned. Root canal cleanliness was evaluated with the aid of a Nikon light microscope (x40 and x100) and scanning electron microscope (x1000 and x3000). The debris scores obtained at three canal regions were compared statistically within the same group and among different groups using repeated measurements of analysis of variance (anova) with Bonferroni adjustments and anova with posthoc Tukey HSD, respectively. RESULTS: The canals treated with EDTA and Glyde File Prep were significantly cleaner than those treated with NaOCl alone. The apical region of the root canals generally displayed more residual smear layer, but the difference was not significant. CONCLUSIONS: Used in conjunction with NaOCl irrigation, Glyde File Prep was effective in removing smear layer produced during root canal instrumentation.

Instability in a laser-diode-pumped microchip Nd:YAG laser in a n-ary product scheme.

Dynamical instability, chaotic pulsations, and generalized bistability have been observed in a laser-diode-pumped microchip Nd:YAG laser operating in a double transition scheme in which lasing occurs on two transitions with overlapping gain profiles, F(3/2)(4)(2)? I(11/2)(4)(3) and F(3/2)(4)(1)? I(11/2)(4)(2), and simultaneously involves excited Nd atoms from different sublevels of the upper manifold. The modeling of the experimental results requires rate equations that include cross-gain coupling among oscillating modes that belong to different transitions whose population inversion densities are determined by the Boltzmann distribution.

Association of tocolytic therapy with antenatal steroid administration and infant outcomes. Newborn Lung Project.

The use of tocolytic agents to halt premature labor is controversial. We examine a database on very low-birth-weight infants born following the onset of premature labor (n = 540) for association between tocolytic and antenatal steroid therapy, and to assess neonatal and childhood outcomes following combined therapy. Data are from a multicenter regionally based study of all infants below 1501 g at seven neonatal intensive care units (NICUs) in Wisconsin and Iowa, born August 1, 1988 through June 30, 1991. Infant outcomes analyzed are death in the first 30 days, respiratory distress syndrome (RDS), and intraventricular hemorrhage (IVH). Fewer deliveries occurred within 12 hours of labor onset with tocolytics (61 vs. 75% without). A strong association between tocolytic therapy and antenatal steroid administration was found [adjusted odds ratio OR = 5.7, 95% confidence interval CI: (3.3, 10.0)]. Tocolytics were associated with lower mortality in the first 30 days [OR = 0.29, CI: (0.15, 0.56)]. Joint administration of tocolytics and antenatal steroids versus neither was associated with lower incidence of the combined outcome of respiratory distress syndrome (RDS) or death [OR = .30, CI: (0.15, 0.60)] and grade III-IV IVH or death [OR = 0.35, CI: (0.14, 0.98)]. Tocolytic therapy alone was not associated with IVH grade III-IV [OR = 1.0, CI: (0.57, 1.9)] among survivors.

College students' trait ratings of three age groups around the Pacific Rim.

In this paper, the traits which younger adults associate with younger, middle-aged, and older adults in a number of Pacific Rim nations were assessed. Two dependent variables ('personal vitality' and 'benevolence') emerged from factor analyses of a series of trait adjectives. Cross cultural trends emerged which replicated patterns found in the US context. Main effects indicated declines in ratings of personal vitality and increases in ratings of benevolence with increasing target-age. However, interesting variations on this pattern emerged in different cultures. In particular, very negative evaluations of aging in Hong Kong, and a lack of differentiation between middle-aged and older adults in the Philippines and New Zealand were found. Little evidence emerged supporting the notion of particular positive evaluations of older adults in Asian cultures.

A computer program in QuickBasic for the selection of tests for the identification of Helicobacter pylori.

Reliable microbiological tests are needed for the identification of bacteria. A program has been written in QuickBasic to identify such tests by using a formula that is based on Gyllenberg's Sum of C(i) and Gyllenberg's Rank R(i). A total of 139 papers on a newly isolated bacterium, Helicobacter pylori, was used as data source for the coding of test results into an input file. The program outputs a list that aids in the determination of suitable tests for the identification of H. pylori. These tests chosen by the formula were found to be correctly identified as supported by later publications on the bacterium.

Influence of primary tumor site on host anti-tumor immunity.

Stage IV-S neuroblastoma, characterized by a primary tumor plus disseminated tumors in liver, skin and bone marrow, has a favorable clinical prognosis when compared to metastatic Stage IV neuroblastoma. This favorable outcome also characterized mice receiving tumor transplants to these "IV-S" sites. We report the testing of the hypothesis that enhanced anti-tumor immunity in "IV-S" site neuroblastoma recipients explains this improved survival. A million murine C1300 neuroblastoma cells were inoculated into 256 A/J mice to either "IV-S" sites of skin, liver, peritoneal cavity, or to the disseminated stage "IV" sites of subcutaneous tissue, muscle, kidney and lung. After 21 and 28 days of tumor growth, spleen cells from tumor bearing mice were harvested and analyzed by a 51 Cr release lymphocytotoxicity assay. Cytotoxic T cell activity was consistently higher at day 28 than day 21. In the liver and in the peritoneal cavity, cytotoxic T cell activity was higher than in other organs, and at day 28 these values were significantly higher than Stage "IV" sites. On the other hand, skin is not a immunologically privileged site in vivo study.

Astigmatism following cataract surgery: comparison of a scleral and a corneal incision in a mixed group of patients with and without glaucoma.

We retrospectively analysed the course of postoperative corneal astigmatism and corrected visual acuity after extracapsular cataract extraction and posterior chamber lens implantation with either a corneal or a scleral incision in 170 eyes of 155 patients with and without glaucoma. A continuous 10/0 nylon shoelace suture was used for wound closure in two groups. In a third group, corneal wound closure was performed with a shorter shoelace suture in combination with two vicryl wing sutures at 11 and 1 o'clock. Although early postoperative mean astigmatism in eyes operated through a corneal incision was high (range 2.92-6.67 diopters at 1 month postoperatively) and significantly different when compared to eyes operated through a scleral incision (1.96 diopters), final mean astigmatism did not differ significantly between those two groups. Moreover, in 27% of eyes operated through a corneal incision, mean astigmatism at 2 months postoperatively was not significantly different from the scleral group and suture removal was not necessary. There was no statistically significant difference in corrected visual acuity over the entire study period between groups. Since safety and functional results of the corneal incision were not different from the scleral incision, we prefer a corneal incision in cataract surgery because of its surgical advantages, especially in patients with cataract and coexisting glaucoma.

The role of fine needle aspiration for breast cancer in the climacteric--a preliminary report.

Fine needle biopsy has been used with great accuracy in the diagnosis of breast tumours. There have been few reports on its efficacy as an adjunct to other breast screening techniques like x-ray mammography. Abnormal mammograms in the absence of a palpable breast lump are sometimes detected in the climacteric and these pose a problem of tissue sampling for pathologic diagnosis. We have tried to evaluate the technique of radiologically guided fine needle aspiration in such patients. Our report is of an initial series of 13 cases of non-palpable, mammographically abnormal breast lesions. Eight cases were fibroadenoma, 4 cases mammary dysplasia and 1 a benign breast lesion. Representative cytologic samples were obtained in 11 of our 13 cases. Cytologic diagnosis should be correlated with mammographic findings.

Vagino-peritoneal fistula from a cervical carcinoma.

Locally advanced cervical carcinoma may present with a recto-vaginal or a vesico-vaginal fistula but these are more commonly complications following surgery, radiation, or combination therapy for advanced disease. A vagino-peritoneal fistula in a patient with a cervical carcinoma at initial presentation is reported. The method of confirming the diagnosis, problems of stage allocation, and management are discussed.