Effect of trapping on hydrogen permeation

Approximate solutions were obtained to the nonlinear partial differential equations derived by A. McNabb and P. K. Foster for a general model of diffusion-plus-trapping. The finite-difference method was applied to their equations for boundary conditions appropriate to hydrogen permeation and evolution in a plane. Solutions are shown to be stable and to converge to the exact solutions in certain limiting cases. The effect of trapping on hydrogen permeation and evolution was explored for a range of parameter values from computer generated tables of concentrations of diffusing and trapped hydrogen. General characteristics of the transient stages of permeation in the presence of trapping are inferred from the results.     

Effect of trapping on hydrogen permeation

Approximate solutions were obtained to the nonlinear partial differential equations derived by A. McNabb and P. K. Foster for a general model of diffusion-plus-trapping. The finite-difference method was applied to their equations for boundary conditions appropriate to hydrogen permeation and evolution in a plane. Solutions are shown to be stable and to converge to the exact solutions in certain limiting cases. The effect of trapping on hydrogen permeation and evolution was explored for a range of parameter values from computer generated tables of concentrations of diffusing and trapped hydrogen. General characteristics of the transient stages of permeation in the presence of trapping are inferred from the results.     

Antitumor effect of positively charged resin in the hamster cheek pouch model

This paper presents the results of a detailed study of the pain epidemiology and health related quality of life (HRQL) in 150 chronic non-malignant pain patients consecutively referred to a Danish multidisciplinary pain center. Mean pain severity was 71.6 (SD = 18.5) on the VAS scale. Forty-two percent reported poor quality of sleep. HRQL was evaluated with the Medical Outcome Study-Short Form (SF-36), the Hospital Anxiety and Depression scale (HAD) and the Psychological General Well-Being Scale (PGWB). Compared with the normal population (NP) both SF-36 scores and PGWB scores were significantly reduced (P < 0.001) indicating that physical, psychological and social well-being were severely reduced. On the HAD scale 58% were found to have a depressive or anxiety disorder. Statistically significant but modest correlations were found between pain severity and HRQL. Psychological and social well-being was closely correlated. Sixty-three percent of the referred patients had neurogenic pain conditions. Of these, only 25% were treated with antidepressants or anticonvulsants at referral. Seventy-three percent were treated with opioids at referral. Mean opioid consumption was 64 mg of morphine per day (range 1-280 mg). Compared with the NP the chronic pain patients had used the health care system five times more often in the years prior to referral (P < 0.001). The study confirms the severe multidimensional impact of chronic pain and demonstrates that HRQL of chronic non-malignant pain patients is among the lowest observed for any medical condition.     

NMR study on the binding of d(GGAAATTTCC)2 with a positively charged pentacosapeptide

To obtain a better understanding of the electrostatic nature of protein-nucleic acid interactions, we have investigated the interaction of a double-stranded decamer d(GGAAATTTCC)2 with a synthetic arginine and lysine-rich pentacosapeptide (Pep25), using NMR and optical spectroscopy. The chemical shift data of the decamer under various experimental conditions show that the binding of Pep25 changes the conformation of the decamer in a different way, as compared to the conformational changes induced by a variation in temperature or ionic strength. The chemical shift results are interpreted in terms of ring current effects that emerge into a model for the conformational change, in which the double-stranded helix of the decamer undergoes a decrease of twist and rise to accommodate Pep25. The binding results indicate that the positively charged arginine and lysine side chains of Pep25 not only have a stabilising electrostatic interaction with the negatively charged backbone phosphates of d(GGAAATTTCC)2, but also that a stabilisation of the base pairs of d(GGAAATTTCC)2 by Pep25 takes place.     

Separation and identification of positively charged and neutral nucleoside adducts by capillary electrochromatography-microelectrospray mass spectrometry

Capillary electrochromatography (CEC) is shown to be capable of separating mixtures containing both positively charged and neutral styrene oxide-adenosine adducts. In a study of the mechanism of deamination of positively charged 1-(2-hydroxy-1-phenylethyl) adenosine using 18O-labeled water, possible contamination of the chromatographically purified deamination product, 1-(2-hydroxy-1-phenylethyl) inosine, with the positively charged 1-(2-hydroxy-1-phenylethyl) adenosine was observed. Because the deamination product and the presumed contamination have the same molecular weights and similar structures, CEC-microelectrospray mass spectrometry (CEC-microESI/MS) was used to confirm the presence and identity of the suspected impurity. A trace amount of the positively charged 1-(2-hydroxy-1-phenylethyl) adenosine, which could not be observed by either HPLC-UV or CEC-UV, was detected by CEC-microESI/MS. This discriminatory ability of CEC-microESI/MS is attributed to the fact that positive ion mode ESI-MS is a more sensitive detector for a positively charged compound than a UV detector, and that the combination of electroosmotic and electrophoretic flows and hydrophobic interactions with the stationary phase contributes to the separation of the positively charged compound. As a result, the positively charged compound was observed to elute much earlier and with much sharper peaks than the neutral compounds for which electroosmotic flow is the only "pumping" force for the solvent.     

Effect of phosphatidylcholine and cholesterol on pH-sensitive liposomes

We previously reported that liposomes composed of phosphatidylethanolamine (PE) and fatty acid exhibited pH-dependent leakage, aggregation and fusion (N. Hazemoto, M. Harada, N. Komatubara, M. Haga and Y. Kato, Chem. Pharm. Bull., 38, 748 (1990)). In this study, we have examined the effects of phosphatidylcholine (PC) and cholesterol (Chol) on the pH-sensitivity of liposomes. Contents-leakage from liposomes was always accompanied by a change in light-scattering, suggesting that aggregation or fusion of liposomes causes the leakage. The pH-sensitivity was observed only when liposomes contained less than 32 mol% of PC. The leakage vs. pH curves shifted to the more acidic regions as the PC content of the liposomes increased, but the maximum leakage (%) did not change. The effect of cholesterol on the pH-sensitivity depended on the PC/PE ratio of the liposomes. Addition of cholesterol to PC/PE/oleic acid (OA) liposomes system induced two effects, that is, aggregation of liposomes via the reduction in PC content and the stabilization of the liposomal membrane. It was shown that pH-sensitivity can be controlled by addition of the appropriate amount of PC and/or Chol to liposomal lipids.     

Biodegradable positively charged ion exchange beads: a novel biomaterial for enhancing soft tissue repair

This article presents a simple and efficient articulator to help with the registration of maxillomandibular relationships, mounting casts, and subsequent perfection of the occlusal scheme for various types of prosthodontic restorations. The system (Individual Anatomo-Physiological system), which is composed of the articulator and recommended procedures, allows for registration of positions and trajectories of the mandible at the level of the patient's occlusal plane. It is used to accurately transfer the records to the articulator. A luminous signal shows the correct centric occlusal relationship and vertical dimension, in both clinical and laboratory procedures. Interocclusal records are used for semiadjustment of the articulator for provisional restorations and stereographic records are used for full adjustment of the articulator for definitive treatment.     

Positioning of positively charged residues in the V3 loop correlates with HIV type 1 syncytium-inducing phenotype

The effects of urinary symptoms on health-related quality of life (HRQL) are important in therapeutic decision making. Few have evaluated the treatment effects on HRQL in men with benign prostatic hyperplasia (BPH), even though increased urinary symptoms are associated with greater worry, bother, and interference with living activities. We report on patient assessments of such disease-specific measures as well as general HRQL measures from two placebo-controlled clinical trials of finasteride in the treatment of symptomatic BPH. Patients treated with finasteride appeared to have greater improvement than placebo-treated patients in disease-specific measures and in patient global assessment. The treated group appeared to have a greater mean increase in sexual domain scores. As expected, general measures (health rating, life satisfaction, ladder of life) changed little. Thus, treatment with finasteride appears to reduce bother, worry, and activity interference due to symptoms but in a small percentage of men may lead to slightly reduced sexual function.     

Effect of N-acylethanolamines with different acyl-chains on DPPC multilamellar liposomes

Relationships between lower extremity strength and stride characteristics were studied in 24 patients with post-polio syndrome. Maximum isometric torques were measured in the ankle plantar flexors, hip and knee extensors, and hip abductors. Gait velocity, stride length, and cadence were recorded during free and fast walking. Step-wise regression analysis was performed to determine which muscle groups best predicted ambulatory function. Plantar flexion torque was the best predictor of velocity (r = .55 free walking and r = .76 fast) and cadence (r = .46 free and r = .58 fast). The combination of plantar flexion and hip abduction torques was the best predictor of fast stride length (r = .78). These findings emphasize the important role of the plantar flexor muscles in gait. Knee extension torque was the poorest predictor for each of the gait parameters. Several patients demonstrated gait deviations that minimized the penalty of quadriceps weakness. Without a contracture or an orthosis, however, no adequate substitution exists for weak plantar flexion.     

Effect of fractal dimension on drug permeation through porous ethylcellulose films

This paper describes a pilot investigation of first year nursing students' adherence to the recommended auscultatory blood pressure measurement procedure following three different forms of instruction; conventional classroom demonstration of the technique, a self instructional CD-ROM tutorial program, and a combination of both methods. This investigation was carried out over a 5-day time period using 27 students during normal teaching time. Students' adherence to the procedure was determined by observation using a performance checklist. Results suggest that the CD-ROM is no substitute for real life, hands on experience, although when used as an adjunct to traditional teaching methods, it can enhance learning.     

Effect of vehicles on yohimbine permeation across excised hairless mouse skin

We aimed to provide a detailed analysis of substance P (SP)-containing nerves in the trabecular meshwork by ultrastructural immunohistochemistry and capsaicin treatment for chemical ablation of the sensory nerves. Numerous myelinated and unmyelinated nerves were observed inside the sheets and intertrabecular spaces of the trabecular meshwork, and the inner side of Schlemm's canal. SP-like immunoreactive products were identified in some of these nerves and associated with numerous vesicles of different sizes, a few mitochondria and numerous neurotubili. After the capsaicin treatment, SP-like immunoreactive nerves persisted and no degenerated SP-like immunoreactive nerves were noted. On the basis of the ultrastructural features and the results of capsaicin treatment, it seems that these nerves are most probably autonomic in origin. Autonomic efferent SP-containing nerves are confirmed directly located in the trabecular meshwork; these have not been previously described at electron microscopic level. SP in autonomic efferent nerves might act as a neurotransmitter or neuromodulator for intraocular pressure regulation.     

Effect of electrodeposited metals on the permeation of hydrogen through iron membranes

The permeability of electrolytically charged hydrogen through annealed Ferrovac E iron membranes was found to decrease significantly upon coating the charging surface of iron with thin layers of either Pt, Cu or Ni (Watts or electroless). The absorption of hydrogen was delayed for a period which depends on the nature and the thicRness of the metallic coating. The results show that such coatings do not have to be thicR or even continuous to be effective, in which case a catalytic mechanism is proposed to explain the marRed reduction in hydrogen permeation through the iron. Experimental confirmation is presented of this catalytic mechanism and of the barrier mechanism which is operative in the presence of dense continuous coatings. It is also shown that a decrease in catalytic activity occurs with time (aging) and is pronounced in the presence of As³⁺ ion. Formerly Research Associate, The Pennsylvania State University