MEMS lubricants based on bound and mobile phases of hydrocarbon compounds: film deposition and performance evaluation

The concept of a thin layer of mobile hydrocarbon-based lubricant providing protection by replenishment to a surface already protected by a chemically bound material has been explored for the first time, for application to silicon-based microelectromechanical (MEMS) systems. Several bound/mobile pairs of lubricants were evaluated to study the effects of bound phase end group and mobile phase chemical functionality on wettability and performance. The bound species studied were derived from 1-decanol and 1,7-heptanediol. Mobile phases investigated were, a pentaerythritol ester, a multiply alkylated cyclopentane, Pennzane, and a polysilane developed for spacecraft application. Hydrocarbon lubricant performance was evaluated using electrostatic motors run in dry air, and was compared with that provided by Fomblin Zdol under identical conditions. Motors with hydrocarbon coatings showed substantial improvement in performance over uncoated motors, and for some bound/mobile pairs, was equal to Zdol within experimental error. We believe that for silicon-based devices, hydrocarbon coatings will be preferable at least for some applications, as the degradation observed due to aging of a fluorinated lubricant in direct contact with a silicon surface is absent.     

Determinant spreading associated with demyelination in a nonhuman primate model of multiple sclerosis

Definition of the immune process that causes demyelination in multiple sclerosis is essential to determine the feasibility of Ag-directed immunotherapy. Using the nonhuman primate, Callithrix jacchus jacchus (common marmoset), we show that immunization with myelin basic protein and proteolipid protein determinants results in clinical disease with significant demyelination. Demyelination was associated with spreading to myelin oligodendrocyte glycoprotein (MOG) determinants that generated anti-MOG serum Abs and Ig deposition in central nervous system white matter lesions. These data associate intermolecular "determinant spreading" with clinical autoimmune disease in primates and raise important issues for the pathogenesis and treatment of multiple sclerosis.     

Long-term expression and secretion of human glucocerebrosidase by primary murine and human myoblasts and differentiated myotubes

The majority of studies dealing with DNA analyses are made on fixed cells. In this context, the efficiency as fixatives of ethanol, methanol, acetone, Carnoy, Boehm-Sprenger and aldehydes was determined using two different DNA fluorescent probes, Hoechst 33342 and propidium iodide. The purpose of our study was to find the fixative that would provide the best results with respect to the following parameters: aggregates, cell size and granularity, and DNA staining analysis. Using murine fibroblasts, we found that 68% ethanol, 85% methanol and aldehydes did not increase aggregate formation, whereas Carnoy, acetone or Boehm-Sprenger fixatives did. The results show that aldehydes seem to alter cell size least. All fixatives induce an increase in cell granularity, which is very pronounced with alcohols, but aldehydes alter morphology less than alcohols. We observed that the fixatives giving the best resolution with Hoechst 33342 staining lead to a lower measurement variability than with propidium iodide staining. This study leads us to conclude that 68% ethanol and 85% methanol can be considered as appropriate fixatives for flow cytometry studies of DNA content.     

Outcome of long-term enteral feeding

In the past two decades, many technical advances have made tube enteral feeding much more comfortable and acceptable to patients and their families. This has greatly expanded the use of this therapy, both in clinical conditions where it was traditionally prescribed and in many other diagnoses. This expanded use raises important questions about how much enteral nutrition is being used, the medical outcome in different clinical conditions, and the quality of life experienced by long-term therapy users. This article addresses these outcome issues for patients in the nonhospital setting.     

Association of glyceraldehyde-3-phosphate dehydrogenase expression with cell motility and metastatic potential of rat prostatic adenocarcinoma

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) expression is increased in Dunning R-3327 rat prostatic adenocarcinoma cell lines relative to normal rat ventral prostate tissue. GAPDH expression closely correlates with cell motility of Dunning prostate cancer cell lines and accurately distinguishes cell lines with high metastatic potential from those with low metastatic potential. Increased GAPDH expression in the cancer cell lines is not simply related to increased growth rate, since rapidly proliferating normal prostate tissue did not exhibit elevated GAPDH expression.     

Long-term T cell memory requires the surface expression of self-peptide/major histocompatibility complex molecules

How memory T cells are maintained in vivo is poorly understood. To address this problem, a male-specific peptide (H-Y) was identified and used to activate female anti-H-Y T cells in vitro. Anti-H-Y T cells survived in vivo for at least 70 days in the absence of antigen. This persistence was not because of the intrinsic ability of memory T cells to survive in vivo. Instead, the survival and function of adoptively transferred memory cells was found to require transporter of antigen protein 1-dependent expression of self-peptide/major histocompatibility complex class I molecules in recipient animals. Therefore, it appears that the level of T cell receptor engagement provided by transporter of antigen protein 1-dependent, self-peptide/major histocompatibility complexes is sufficient to maintain the long-term survival and functional phenotype of memory cells in the absence of persistent antigen. These data suggest that positive selection plays a role not only in T cell development but also in the maintenance of T cell memory.     

In vitro antimycobacterial activity of 5-chloropyrazinamide

5-Chloropyrazinamide and 5-chloropyrazinoic acid were evaluated for in vitro activity against Mycobacterium tuberculosis, Mycobacterium bovis, and several nontuberculous mycobacteria by a broth dilution method. 5-Chloropyrazinamide was more active than pyrazinamide against all organisms tested. It is likely that this agent has a different mechanism of action than pyrazinamide.     

Use of cardiopulmonary bypass to salvage patients with multiple-chamber heart wounds

BACKGROUND: The need for cardiopulmonary bypass in the treatment of penetrating heart injuries is debated. OBJECTIVES: To review our experience with penetrating heart injuries and determine the indications and outcome for cardiopulmonary bypass. DESIGN: Retrospective review. SETTING: A university-based, level I trauma center. PATIENTS: All victims of penetrating heart injury presenting between July 1, 1989, and December 31, 1995. METHODS: Medical records were reviewed for demographic and physiological data, operative findings, and outcome. RESULTS: Overall survival for 106 patients with penetrating heart injury was 55%. In an effort to resuscitate the heart, 4 patients with unresponsive cardiogenic shock were placed on cardiopulmonary bypass; none survived. Of 30 patients with multiple-chamber injuries, 11 presented with signs of life and 7 survived. Cardiopulmonary bypass was essential to repair complex injuries in 2 of the 7 survivors. CONCLUSION: Cardiopulmonary bypass was ineffective in salvaging patients with cardiogenic shock but was essential in some patients with complex multiple-chamber cardiac injuries that could not be exposed and repaired by other means.     

Prospects of glutamate antagonists in the therapy of Parkinson''s disease

BACKGROUND AND AIMS OF THE STUDY: Several different biological, bioprosthetic and mechanical devices are available for heart valve replacement. We present a quantitative methodology to estimate the (event-free) life-expectancy and lifetime risk of valve-related events for individual patients after implantation of any one of these valve types. METHODS: We modelled the age-dependent prognosis of a patient after aortic valve replacement with a discrete-time Markov model and Monte-Carlo simulation to estimate (event-free) life-expectancy and life-time risk of valve-related events, respectively. Quantitative estimates to parameterize these models used hypothetical devices and presumed data were based on a limited review of published literature. RESULTS: This decision-analytical approach allowed an estimation of the overall and event-free life-expectancy as well as the lifetime risk of valve-related events after implantation of different types of prosthetic heart valve in the aortic position. In the current, hypothetical model, one valve type excelled for all age groups in terms of life expectancy and life-time risk of valve-related events. The choice of the second-best alternative varied according to patient age and comorbidity. Sensitivity analyses showed results to be especially dependent on the durability of the replacement valve and surgical risk. CONCLUSIONS: This methodological approach is very flexible, and its quantitative results may guide decision making, if increasing quantitative information on heart valve prosthesis performance becomes available in future. Markov models and Monte Carlo simulation may be used to obtain a better understanding of the effect that different types of prosthetic heart valves have on patient prognosis, while quantitative results may help cardiologists and cardiac surgeons to choose a specific valve type for an individual patient.