Chronic stress and endothelial dysfunction: mechanisms, experimental challenges, and the way ahead

Although chronic stress is an important risk factor for cardiovascular diseases (CVD) onset, the underlying mechanisms driving such pathophysiological complications remain relatively unknown. Here, dysregulation of innate stress response systems and the effects of downstream mediators are strongly implicated, with the vascular endothelium emerging as a primary target of excessive glucocorticoid and catecholamine action. Therefore, this review article explores the development of stress-related endothelial dysfunction by focusing on the following: 1) assessing the phenomenon of stress and complexities surrounding this notion, 2) discussing mechanistic links between chronic stress and endothelial dysfunction, and 3) evaluating the utility of various preclinical models currently employed to study mechanisms underlying the onset of stress-mediated complications such as endothelial dysfunction. The data reveal that preclinical models play an important role in our efforts to gain an increased understanding of mechanisms underlying stress-mediated endothelial dysfunction. It is our understanding that this provides a good foundation going forward, and we propose that further efforts should be made to 1) more clearly define the concept of stress and 2) standardize protocols of animal models with specific guidelines to better indicate the mental complications that are simulated.

ISBT Code 128 implementation at a regional blood center

BACKGROUND

Application specifications for ISBT 128 bar code symbology and the International Council for Commonality in Blood Bank Automation (ICCBBA) were created in 1994. By June 2000, the FDA considered ISBT 128 a standard for uniform labeling of blood and blood components. Our blood center initiated a change process for ISBT 128 implementation and "went live" in 2003.

STUDY DESIGN AND METHODS

The intention to adopt ISBT 128 symbology with hospitals was actively communicated in October 2001. A Codabar-ISBT label cross-reference book was developed, FDA approval for the fullface label format in April 2002 was requested, and FDA approval was received in March 2003. In December 2002, donor identification labels and number sets were ordered, and an integration test plan was subsequently developed with departmental process flowcharts for each of the nine affected departments. Each step was tested, the labeling changes were approved in May 2003, training was completed in June 2003, and ISBT bar code symbology was implemented on July 1, 2003. A written survey was sent to hospital transfusion services in April 2004.

RESULTS

Implementation went smoothly except for an unanticipated high rate of "no-reads" on some analyzers in the testing lab. The hospitals spent an average of 18 hours preparing for changes, 14 hours on validation, 4 hours on documentation and procedure development, and 8 hours on training.

CONCLUSION

ISBT bar code symbology was successfully implemented. Hospital transfusion services made some adjustments and, overall, readily accepted the new bar code symbology.

Cefprozil versus high-dose amoxicillin/clavulanate in children with acute otitis media

BACKGROUND

The recommendation of the Drug-Resistant Streptococcus pneumoniae Therapeutic Working Group that high-dose amoxicillin, with or without clavulanate, be used to treat acute otitis media (AOM) addressed concerns about the efficacy of existing therapies against drug-resistant S. pneumoniae. This recommendation relied on pharmacodynamic predictions of concentrations of amoxicillin in middle-ear fluid remaining higher than minimum inhibitory concentrations against intermediately resistant S. pneumoniae for >40% of the dosing interval.

OBJECTIVE

This study compared the tolerability and efficacy of cefprozil and high-dose amoxicillin/clavulanate in patients with AOM.

METHODS

Patients were randomized to receive 10 days of investigator-blinded oral treatment with either cefprozil suspension (30 mg/kg/d in 2 divided doses) or amoxicillin/clavulanate (45/6.4 mg/kg/d) plus amoxicillin (45 mg/kg/d) in 2 divided doses. The primary efficacy end point was the clinical cure rate 4 to 7 days after the end of treatment. Clinical response by age (6 months-<2 years vs > or =2-7 years), disease severity, and unilateral versus bilateral ear infection was also examined. The primary measures of tolerability were the frequency and severity of adverse events and their relation to study drug. Adverse events were either spontaneously reported or elicited during examination and questioning of the patient. Identified adverse events were coded and recorded using the COSTART (Coding Symbols for Thesaurus of Adverse Reaction Terms) system.

RESULTS

Three hundred four children between the ages of 6 months and 7 years with > or =1 sign or symptom of AOM were enrolled in the study, and 303 (150 cefprozil, 153 amoxicillin/clavulanate) were treated. Twenty-three patients in each treatment group were not evaluable; thus, 257 children were included in the analysis of evaluable patients. Clinical cure rates were 87% (110/127) with cefprozil and 89% (116/130) with amoxicillin/clavulanate (95% CI for the difference in cure rate, -10.7% to 4.1%). No between-group differences in efficacy were noted by age, disease severity, or unilateral or bilateral involvement. The overall incidence of drug-related adverse events was significantly lower with cefprozil than with amoxicillin/clavulanate (19% vs 32%, respectively; P = 0.008), as was the incidence of diarrhea (9% vs 19%, respectively; P = 0.021). Adverse events prompted discontinuation of therapy in 4 (3%) cefprozil patients and 8 (5%) amoxicillin/clavulanate patients.

CONCLUSIONS

Based on a search of MEDLINE, this study is the first direct comparison of cefprozil versus high-dose amoxicillin/clavulanate. Cefprozil was as effective as high-dose amoxicillin/clavulanate, with a lower incidence of adverse events.

Simethicone in the treatment of infant colic: a randomized, placebo-controlled, multicenter trial

OBJECTIVE

To determine the efficacy of simethicone in the treatment of infant colic.

DESIGN

Randomized, double blind, placebo-controlled.

SETTING

Three general pediatric practices in distinct geographic regions.

PATIENTS

Eighty-three infants between 2 and 8 weeks of age with infant colic.

INTERVENTIONS

Treatment with simethicone and placebo in double blind crossover fashion.

RESULTS

A total of 166 treatment periods, ranging from 3 to 10 days, were evaluated in the 83 infants. Compared to baseline, improvement in symptoms was reported for 54% of the treatment periods, worsening was reported for 22%, and, for 24%, there was no change. The likelihood of the treatment period being rated as showing improvement, worsening, or no change was the same whether the infant was receiving placebo or simethicone. Twenty-eight percent of he infants responded only to simethicone, 37% only to placebo, and 20% responded to both. No statistically significant differences were noted among these three groups of responders. No difference could be shown even when infants with "gas-related symptoms" (by parental report) were separated out as a group.

CONCLUSION

Although both produced perceived improvements in symptoms, simethicone is no more effective than placebo in the treatment of infantile colic.

Standardization and analysis of digitized photographic data in the longitudinal documentation of cataractous growth

Age-related cataract formation in man can be documented with slit and retroillumination photographs. With digitization and image analysis of such photographs a cataract may be characterized by a frequency distribution of picture elements over a 255 step gray scale spectrum. Transition from a clear to a cataractous lens may be manifested as a change from a unimodal, Gaussian to a multimodal, non Gaussian frequency distribution respectively. How should one compare and contrast these two distributions, so to accurately describe the extent and significance of a change in lens opacification? The in vitro system of cold cataract formation in the rabbit lens was used as a model of the much slower process of age-related cataract formation in man. As in the human lens undergoing progressive opacification, the frequency distribution (number of pixels vs. intensity of gray) for a digitized image of a clear lens at 26 degrees C is unimodal and Gaussian; that of a fully developed cold cataract at 10 degrees C is multimodal and non-gaussian. In spite of the increasing multimodality of the frequency distribution as the temperature dropped and the cataract grew in density and size, the mean gray density proved to be a valid and useful measure to characterize the distribution and to compare different unaligned images. The Wilcoxon Rank Sum Test proved to be useless in comparing the frequency distributions from cataract images because it proved to be too sensitive to subtle changes in the degree of opacification. Anomalous behavior of the opacification process--i.e. clarification as well as opacification of the lens during cold cataract formation caused all pairs to appear statistically significantly different when in appearance there was no difference. The mean of the frequency distribution is less sensitive to this anomalous behavior and is useful as a comparative index. The method of calculating the threshold of significant change in the mean density of a cataract image is presented.

On the possibility of nonthermal biological effects of pulsed electromagnetic radiation

Two mechanisms for the interaction of alternating electrical fields with biological tissue are the development of heat, via i(2)R losses, and field-induced force effects, via differences in passive electrical properties. It has been shown that for continuous wave (CW) fields in media of physiologic electrical conductivity, the development of heat (>1 degrees C) always precedes the possible appearance of a field-induced force effect. Using pearl-chain formation as a model effect and experimentally demonstrating that its time constant varies inversely as the square of the electrical field strength, we show that a pulsed field has no greater ability than a CW field of equal rms field strength to produce a field-induced force effect. Thus, the statement above for CW fields can be broadened to include pulsed fields of any description. By relating incident power density to electric field strength in tissue, we show that the American National Standards Institute's radiation protection guide obviates the production of genetic effects in man, if they exist, via field-induced force effects.