Corneal pathophysiology with contact lens wear

Contact lens wear induces a wide spectrum of changes in the appearance and function of the cornea. The most salient effect of lens wear is the hypoxically induced reduction in the rate of metabolic activity of the corneal epithelium and its sequellae. Other important alterations to corneal health associated with contact lens wear may be caused by antigenic and toxic stimuli, mechanical forces, osmotic effects and carbon dioxide retention. Perhaps the most important task facing the contact lens clinician is to distinguish between an acceptable state of physiological modification and an anomalous or pathological state of hypofunction. In this article, we review the assortment of corneal changes primarily on the basis of the causative agents and time scale with reference to the physical and chemical processes leading to the observed signs or symptoms. This procedure allows a strong foundation for understanding the etiology and management principles for the variety of effects that contact lenses may have on the cornea.     

Repeat hepatic resections for metastatic colorectal cancer.

OBJECTIVE: The authors weighed the risks and benefits of repeat liver resections for colorectal metastatic disease. METHOD: In the 6-year period between January 1985 and June 1991, 499 patients underwent liver resections for colorectal metastases at the Memorial Sloan-Kettering Cancer Center. Of these, 25 patients had repeat surgical resections for isolated recurrent disease to the liver. The clinical data for these patients were reviewed. RESULTS: The median interval between the two resections was 11 months. There were no perioperative deaths, and the complication rate was 28%. Median follow-up after the second liver resection is 19 months, with median survival of 17 months for nonsurvivors. Although the median survival after the second resection is 30 months, 20 of the 25 patients have had recurrences with a median disease-free interval of only 9 months. No characteristic of primary or metastatic disease predicted outcome, including time between presentation of the primary and development of liver metastases, disease-free interval after the first liver resection, and bilobar liver involvement. CONCLUSIONS: Although repeat liver resections can be performed safely and improves survival, the likelihood of cure from such resection therapy is low. This likelihood of further recurrences encourage studies of adjuvant or alternative treatments of this population.     

Socioeconomic status and risk for substandard medical care.

OBJECTIVE--To assess whether the socioeconomic status of the patient was associated with the risk of adverse events, defined as medical injuries caused by medical management, and the proportion of these events that resulted from substandard care. SETTING--51 hospitals in New York State. METHODS--Rates of medical injury and substandard care by gender, race, income, and payer status were developed from reviews of 30,195 medical records in New York in 1984. We evaluated these socioeconomic parameters in a multivariate analysis, while controlling for hospital-level factors. RESULTS--We found that uninsured patients (odds ratio, 2.35; 95% confidence interval, 1.40 to 3.95) were at greater risk for substandard care. The characteristics of the hospitals to which patients were admitted did not affect this result. Race, gender, and income were not independently associated with risk for medical injury or substandard care in multivariate analyses. CONCLUSION--Our findings suggest that the uninsured are at greater risk for suffering medical injury due to substandard medical care.     

Ninety-Six Five-Year Survivors After Liver Resection for Metastatic Colorectal Cancer

Background: Studies have consistently confirmed the benefit of liver resection for metastatic colorectal cancer. Few reports, however, have a long enough followup or sufficient 5-year survivors to study the clinical course of patients beyond 5 years.

Study Design: From July 1985 through December 1991, 456 patients underwent liver resection for colorectal metastases. Ninety-six actual 5-year survivors (21%) were identified and their clinical course retrospectively reviewed.

Results: Five-year survivors (n = 96) were more likely to have a Duke’s B primary colorectal carcinoma, fewer than four metastatic lesions, unilobar disease, and a negative histologic margin when compared with patients not surviving 5 years (n = 298). Forty-four (46%) of the 96 five-year survivors had a recurrence after hepatectomy. Of these 44, 19 (43%) were rendered disease free after further treatment. Overall, 71 of the 96 five-year survivors were free of disease at last followup. The actuarial 10-year survival of this group was 78%.

Conclusions: Patients that are disease free 5 years after liver resection are likely to have been cured by liver resection. Patients should be aggressively followed for recurrence because of the potential for further treatment and longterm survival.     

Percutaneous transluminal coronary angioplasty in unstable and stable angina pectoris: a comparison of immediate success and complications.

To determine the success rate and the safety of percutaneous transluminal coronary angioplasty in patients with unstable angina pectoris (group 1) versus stable angina (group 2), we studied 299 consecutive patients who underwent coronary angioplasty of 373 consecutive lesions. Of these patients, 149 had unstable angina pectoris and dilation of 188 arteries. The success rate was high and similar in both groups (95 and 93%, respectively). The groups did not differ in regard to the lesion characteristics, vessels and number of sites dilated except for an increase in the presence of thrombus in the unstable angina group (p < 0.03). Although there was a higher incidence of coronary thrombus and more acute myocardial infarction in group 1, the major complication rate did not differ from that of group 2 and was low in both of them (3 and 2%, respectively). No deaths occurred. Six patients (3 in each group) needed urgent coronary artery bypass grafting while 3 additional patients developed acute Q-wave myocardial infarction (all of them in group 1). Thus, percutaneous transluminal coronary angioplasty is a safe and successful procedure in patients with unstable angina as well as in patients with stable angina pectoris.     

Modern day film-screen combinations do not obey conventional exposure rules

Purpose: Following the widespread adoption of energy-dependent rare earth intensifying screens this study investigates the relevance of two conventions (the 10 kVp and kVp-to-the-4th-power rules) commonly used to calculate the kVp/mAs relationship.Methods: A stepwedge was exposed at standard kVp and mAs setting. The kVp was then increased in increments of 5 kVp, and appropriate mAs values were determined using a densitometer. These values were then compared with approximations from the rules previously mentioned.Results: Wide discrepancies are reported between appropriate and approximated values with the latter overestimating exposure by a factor of two.Discussion: Traditional theorems used to estimate the kVp/mAs relationship should no longer be used in modern imaging departments. Each film screen combination should be evaluated individually to ensure appropriate exposure settings.     

Linking perceptions of the community to behavior: are protective social factors associated with physical activity?

Although the relationship of psychosocial factors to physical activity has been explored, there is increased interest in how perceptions of the community environment influence behavior. However, few methodological studies have incorporated perceptions of the social and community environment (protective social factors) or addressed key measurement issues. Computer-assisted telephone interviews were administered to a national sample of 1,818 U.S. adults. Unadjusted and multivariate-adjusted odds ratios were calculated to compare active and inactive participants by Protective Social Factors (PSF) scores and selected sociodemographics. Confirmatory factor analysis and reliability analysis suggested strong PSF scale psychometric properties (alpha = .92). After adjustment for potential confounders, a 10-point rise in the PSF score resulted in a 12% increased likelihood of meeting Centers for Disease Control and Prevention/American College of Sports Medicine recommendations. Additional analyses indicated that greater perceived PSFs were associated with meeting these recommendations among Whites but not among African Americans.