Reactivation kinetics of 5,5'-dithiobis-(2-nitrobenzoic acid)-modified creatine kinase reactivated by dithiothreitol

The reduction of 5,5'-dithiobis-(2-nitrobenzoic acid)-modified creatine by dithiothreitol has been studied using the kinetic theory of the substrate reaction during modification of enzyme activity as previously described by C.L. Tsou (Adv. Enzymol. Rel. Areas Mol. Biol. 61 (1988) 381-436). The results show that the modified creatine kinase can be fully reactivated by an excess concentration of dithiothreitol in a monophasic kinetic course. The presence of ATP or the transition-state analogue markedly slows the apparent reactivation rate constant, while creatine shows no effect. The substrates creatine-ADP-Mg2+ can induce conformational changes of the modified enzyme but adding NO-3 cannot induce further changes that occur with the native enzyme. The reactive cysteines' location and role in the catalysis of creatine kinase are discussed. It is suggested that the cysteine may be located in the hinge area of the two domains of creatine kinase. The reactive cysteine of creatine kinase may play an important role not in the binding to the transition-state analogue but in the conformational changes caused by the transition-state analogue.     

The use of fiber concentrations for ration formulation

Dairy cattle require fibrous feedstuffs in the diet. However, defining the fiber requirements requires knowledge of many interacting components within the diet as well as how the feed is allocated and processed. To meet the demands of high producing dairy cows for energy, diets consist of large quantities of concentrates and high quality forages containing relatively low amounts of fiber. However, to maintain normal rumen function and milk fat percentage, a large portion of the fiber needs to come from forage. Current National Research Council recommendations are a minimum of 25 to 28% dietary neutral detergent fiber, 75% of which is supplied from forage. Chemical measures of fiber alone are not adequate for ration balancing; fiber varies in its effectiveness at stimulating chewing. This variation is greater when feeds contain high amounts of by-products in place of forages. The effectiveness in stimulation of chewing of fiber is variable as the particle size and retention times of indigestible and digestible fiber vary. Currently, little information exists about the fiber requirements of the cow from immediately postcalving until peak lactation. Early lactation cows are clearly more limited by physical fill than are cows in mid and late lactation. Rations based on nonforage fiber sources (> 45% neutral detergent fiber on a dry matter basis) are being evaluated for early lactation cows. Information is needed to determine the variation in the amount of fermentation acids produced, chewing activity, and amount of saliva secreted as these all contribute to the physical effectiveness of fiber.     

Alternative treatments for a traumatic bone cyst: a longitudinal case report

A patient presented with a large, multilocular, refractory traumatic bone cyst. The radiolucency had increased in dimension since her last recall. Over 11 years, therapy had included needle aspiration biopsies followed by simple curettage and closure, the most common therapy for traumatic bone cysts. However, all treatment had proved unsuccessful for this patient. It was decided to treat the patient with a slightly unique method. After curettage of the lesion, the traumatic bone cyst was packed with a mixture of autogenous blood, harvested autogenous bone chips, and hydroxyapatite.     

Voltage-dependent modulation of T-type calcium channels by protein tyrosine phosphorylation

A T-type Ca2+ channel is expressed during differentiation of the male germ lineage in the mouse and is retained in sperm, where is it activated by contact with the the egg's extracellular matrix and controls sperm acrosomal exocytosis. Here, we examine the regulation of this Ca2+ channel in dissociated spermatogenic cells from the mouse using the whole-cell patch-clamp technique. T currents were enhanced, or facilitated, after strong depolarizations or high frequency stimulation. Voltage-dependent facilitation increased the Ca2+ current by an average of 50%. The same facilitation is produced by antagonists of protein tyrosine kinase activity. Conversely, antagonists of tyrosine phosphatase activity block voltage-dependent facilitation of the current. These data are consistent with the presence of a two-state model, in which T channels are maintained in a low (or zero) conductance state by tonic tyrosine phosphorylation and can be activated to a high conductance state by a tyrosine phosphatase activity. The positive and negative modulation of this channel by the tyrosine phosphorylation state provides a plausible mechanism for the control of sperm activity during the early stages of mammalian fertilization.     

Reductase inhibitor monotherapy and stroke prevention

BACKGROUND: Epidemiologic evidence and meta-analyses of data from early clinical trials suggest that lowering the levels of cholesterol does not reduce the events of stroke. These analyses have not included more recent clinical trials using reductase inhibitors. OBJECTIVE: To conduct a meta-analysis of the effect of reducing cholesterol levels on stroke in all reported clinical trials of primary (n = 4) and secondary (n = 8) prevention of coronary heart disease that used reductase inhibitor monotherapy and provided information on incident stroke. RESULTS: Analysis of combined data from primary and secondary prevention trials showed a highly statistically significant reduction of stroke associated with the use of reductase inhibitor monotherapy (27% reduction in stroke; P = .001). Analysis of secondary prevention trials alone disclosed a similar statistically significant effect (32% reduction in stroke; P = .001). A smaller nonsignificant reduction in stroke was noted in the primary prevention trials (15% reduction in stroke; P = .48). CONCLUSIONS: Reductase inhibitors now in use for lowering cholesterol levels are more potent and have fewer side effects than the cholesterol-lowering agents previously available. They appear to reduce stroke, most notably in patients with prevalent coronary artery disease, which may be partly due to the effects of lowering the levels of cholesterol on the progression and plaque stability of extracranial carotid atherosclerosis or the marked reduction of incident coronary heart disease associated with treatment.     

Principles for assuring the health of college students: a California perspective

Given the rapidity of change in both higher education and health care, re-examining the values and precepts that undergird the profession of college health is an ongoing need. Reported in this article are the results of a structured process in which a group of college health professionals from California, along with others interested in the health of college students, examined several trends affecting higher education and health; considered possible scenarios for these sectors; created a shared vision for the future of college health; and developed strategies useful in attaining that vision. The results of these deliberations are presented as a set of principles that, if followed, should increase the likelihood that college health centers will be responsive to user needs. Although the article is based on a California-based conference, the principles discussed are almost certainly valuable for all in college health.     

Noninvasive blood glucose sensors based on near-infrared spectroscopy

Research into noninvasive devices for self-monitoring of blood glucose is mainly based on near-infrared spectroscopy. Such a device is particularly desirable in the intensive therapy of patients with diabetes mellitus to achieve optimal metabolic control through frequent glucose testing. The state of noninvasive assay technology is presented. Using diffuse reflectance spectra of mucous lip tissue has advantages and drawbacks compared with tissue transmittance experiments. Different approaches have been proposed in the patent literature; however, current technology requires further significant improvements, particularly within the lower normal and hypoglycemic glucose concentration ranges.     

Endoscopically defined treatment strategies in patients with locally advanced esophageal cancer

Sixty-five consecutive, locally advanced esophageal cancer patients were treated by the West Side Medical Center Esophageal Service at the Cook County and University of Illinois hospitals. Each patient was prospectively evaluated with multiple endoscopies including esophagogastroduodenoscopy, bronchoscopy, nasopharyngoscopy, and laryngoscopy. Twenty-four patients (37%) had endoscopic findings that significantly altered therapeutic regimens. Patients identified as having an obvious or impending esophageal fistula or poor performance status were treated in a palliative fashion. Forty (61.5%) patients were considered candidates for treatment with multimodal therapy which included radiation, chemotherapy, and surgery. There was a response rate of 82.5% and a 1-year disease-free survival of 88.9% which was statistically significant when compared to the other patient treatment groups. These data illustrate the necessity of multiple endoscopic evaluation of locally advanced esophageal cancer patients for stratification into appropriate treatment groups. Aggressive treatment afforded selected patients excellent relief of presenting symptomatology, as well as an improved, more acceptable, disease-free survival.     

Assessing work-related body-part discomfort: Current strategies and a behaviorally oriented assessment tool

Work-related body-part discomfort has been assessed for a variety of purposes in both experimental and applied research. In a number of these studies, ‘discomfort’ is assessed using a body map and a rating, or ranking, procedure. Sometimes the assessed values are subjected to direct statistical investigation; at other times the assessed values are used to derive indices of discomfort which are then subjected to statistical study. However, the construct of ‘discomfort’ is rarely clearly defined. Thus, depending on the nature of the investigation, the respondent's perceptions, and the instructions provided, it may incorporate a variety of physical sensations including pain, fatigue, tension, and tingling. This paper describes ways in which work-related body-part discomfort has been defined, assessed, and used. It concludes with a tool for assessing work-related body-part discomfort. This tool includes a body map and scales for assessing the severity, frequency, and duration of work-related body-part discomfort, and incorporates many of the key features identified in this literature review.