Genetics: Changing Health Care in the 21st Century

Advances in human genetics are rapidly changing the scope of information and care that can be provided to health care consumers. By the year 2005 it is expected that the entire human genome will be mapped and all 70,000–100,000 genes will be identified. Currently, there are more than 5,000 known single-gene disorders. With the movement of specialized health services into the primary care setting, nurses increasingly will need to be knowledgeable about genetic disorders, screening/diagnostic tests, and implications for health care. In addition, the management of genetic information raises issues of informed consent, privacy and confidentiality, truth telling and disclosure, and nondiscrimination.     

The EPC Approach to Estimating Safety from Exposure to Environmental Chemicals

Reference doses (RfDs) and reference concentrations (RfCs) developed by the United States Environmental Protection Agency (USEPA) are typically used in the quantitation of risk of potential adverse human health effects from exposure to environmental chemicals. For a large number of chemicals, however, USEPA RfDs and RfCs have not yet been determined. Thus, for risk assessments that involve a large number of chemicals, there is insufficient toxicity information with which to evaluate potential adverse human health effects for all chemicals present at a particular site. Due to this insufficiency, the risk assessor must either (1) ignore potential exposures on the assumption that omitting these exposures does not significantly alter decisions concerning the remediation of the site or (2) undertake a lengthy and costly analysis to generate the necessary RfDs or RfCs. A potential solution to this problem is to develop estimated permissible concentrations (EPCs), values which represent permissible environmental concentrations or related acceptable daily dosages derived from occupational exposure limits. In the present analysis, acceptable daily dosages determined using the EPC method were compared to USEPA RfDs or RfCs which were converted to dosages based on standard exposure assumptions. Based on a comparative analysis of EPCs and USEPA reference values for 103 chemicals, it was found that EPC daily dosages represent a reasonably conservative surrogate value when USEPA or state reference values are unavailable. Given that there are hundreds of chemicals with occupational exposure limits but no state or USEPA reference values, acceptance of the EPC methodology would provide an interim solution for the problem of insufficient toxicity information for a substantial number of environmental chemical contaminants.     

Do women and myopes have larger pupils?

It is commonly reported that the pupils of women are larger than those of men and the pupils of myopes larger than those of emmetropes. However, these reports are not supported by experimental procedures using objective measurements, controlled conditions, and adequate numbers of subjects. In this report the open-loop pupil size was measured objectively using dynamic infrared pupillometry in a sample of 48 subjects. Subjects were balanced for age and equally divided between emmetropes and myopes, males and females. The results did not support the contention that females have larger pupils than males or that physiologic myopes have larger pupils than emmetropes.     

Species-, serogroup-, and serovar-specific epitopes are juxtaposed in variable sequence region 4 of the major outer membrane proteins of some Chlamydia trachomatis serovars.

Synthetic peptides and murine monoclonal antibodies were used to map cross-reactive chlamydial epitopes. A species-specific epitope in the central region of variable sequence region 4 abuts the amino-terminal end of a B-serogroup-specific or F/G-serogroup-specific epitope, which in turn abuts known serovar-specific epitopes. The carboxyl-terminal portion of variable sequence region 4 (residues 297 to 314) comprises a region of end-to-end B-cell epitopes in some serovars of the B and F/G serogroups.     

Assessing quality of life in primary biliary cirrhosis.

BACKGROUND AND AIMS: Assessment of health-related quality of life (HRQOL) is not routinely reported in the literature on chronic liver disease (CLD). Few studies have examined quality of life (QOL) in patients with primary biliary cirrhosis (PBC) despite its significant functional impact. One of the reasons for the lack of HRQOL measurement in patients with PBC may be the absence of a well-recognized and widely used measure that clinicians can use in ordinary clinical practice. The aim of this study is to evaluate HRQOL measures used in patients with PBC and examine the suitability of the measures for these patients. METHODS: A literature search identified reports that focused on any aspect of QOL in patients with PBC. Key texts were identified containing generic, domain-specific, and condition-specific measures. The identified measures were systematically evaluated for appropriateness, acceptability, reliability, validity, precision, and responsiveness. RESULTS: Twenty measures were identified from 9 key texts. Six of the measures were previously validated generic measures; 10 were domain-specific measures previously used to measure fatigue, depression, and psychological distress in general and psychiatric populations; and 4 measures had been developed in patients with CLD. Reporting of reliability and validity generally was consistent for all measures used. However, reporting of the remaining criteria was variable, particularly in relation to responsiveness over time and acceptability of the measures to patients with PBC. CONCLUSIONS: A clearer and more rigorous approach is needed in reporting the properties of HRQOL measures used in patients with PBC to help clinicians decide which measures are most suitable for these patients.     

Dual Effects of Hexanol and Halothane on the Regulation of Calcium Sensitivity in Airway Smooth Muscle

Background: Contraction of airway smooth muscle is regulated by receptor-coupled mechanisms that control the force developed for a given cytosolic calcium concentration (i.e., calcium sensitivity). Halothane antagonizes acetylcholine-induced increases in calcium sensitivity by inhibiting GTP-binding (G)-protein pathways. The authors tested the hypothesis that hexanol, like halothane, inhibits agonist-induced increases in calcium sensitivity in airway smooth muscle by inhibiting G-protein pathways.

Methods: Calcium sensitivity was assessed using [alpha]-toxin-permeabilized canine tracheal smooth muscle. In selected experiments, regulatory myosin light chain phosphorylation was also determined by Western blotting in the presence and absence of 10 mm hexanol and/or 100 [mu]m acetylcholine.

Results: Hexanol (10 mm) and halothane (0.76 mm) attenuated acetylcholine-induced calcium sensitization by decreasing regulatory myosin light chain phosphorylation during receptor stimulation. Hexanol also inhibited increases in calcium sensitivity due to direct stimulation of heterotrimeric G-proteins with tetrafluoroaluminate but not with 3 [mu]m GTP[gamma]S, consistent with prior results obtained with halothane. In contrast, in the absence of receptor stimulation, both compounds produced a small increase in calcium sensitivity by a G-protein-mediated increase in regulatory myosin light chain phosphorylation that was not affected by pertussis toxin treatment.