Penetration of chloroform, trichloroethylene, and tetrachloroethylene through human skin.

In vitro dermal absorption was measured for three volatile organic compounds in dilute aqueous solution through freshly prepared and previously frozen human skin. The permeability coefficients at 26 degrees C for chloroform (0.14 cm/h) and trichloroethylene (0.12 cm/h) were similar but much larger than that for tetrachloroethylene (0.018 cm/h). Storage of the skin at -20 degrees C did not significantly affect the penetration of these chemicals. The dermal absorption of chloroform through freshly prepared human skin was not changed significantly by pretreatment of the skin with commonly used consumer products (moisturizer, baby oil, insect repellent, sunscreen); however, the permeability coefficient was found to increase from 0.071 cm/h at 11 degrees C to 0.19 cm/h at 50 degrees C. These data suggest that exposure estimates for chloroform and other contaminants in water should consider the appropriate exposure scenario to properly assess the dermal dose.

Effect of environmental conditions on the penetration of benzene through human skin.

The in vitro penetration of [14C]benzene through freshly prepared human skin was examined under a variety of skin conditions associated with swimming and bathing. The experimental system utilized a recirculating donor solution and a flow-through receiver solution, and was modified to accommodate the analysis of volatiles. The permeability coefficient of 0.14 cm/h under standard conditions at 26 degrees C was found to increase to 0.26 cm/h at 50 degrees C and decrease to 0.10 cm/h at 15 degrees C. Storage of the skin at- 20 degrees C did not affect the penetration of benzene. Application of baby oil, moisturizer, or insect repellant to the skin before exposure under standard conditions did not affect the flux of benzene, but a significant increase was observed when the skin was pretreated with sunscreen (permeability coefficient 0.24 cm/h). These results suggest that risk assessment or exposure modeling for benzene and other environmental contaminants should account for appropriate changes in the environmental conditions when considering the dermal route of exposure.

The protective effect of antioxidants to a phototoxin-sensitive insect herbivore,Manduca sexta.

Photo-activated plant secondary compounds have been shown to be toxic to many organisms including insects. Insect defenses include behavioral mechanisms such as light avoidance, as well as specific biochemical defenses such as antioxidants and antioxidant enzymes. These antioxidant defenses eliminate or quench the deleterious singlet oxygen and free radicals formed by these phototoxins. In this paper we examined the role of dietary antioxidants in protecting the phototoxin-sensitive insect herbivoreManduca sexta. Elevated dietary levels of the lipid-soluble antioxidantsΒ-carotene and vitamin E resulted in a concentration-dependent reduction in the mortality associated with treatment ofM. sexta larvae with the phototoxic thiopheneα-terthienyl. Elevated levels of dietary ascorbic acid had no effect, whereas reduced levels greatly increased the toxicity ofα-terthienyl. Tissue levels of antioxidants were shown to increase substantially in larvae fed antioxidant-supplemented diets. The results suggest that the ability to absorb and utilize plant-derived antioxidants could be an important defense against photo-activated plant secondary compounds and may have allowed some insects to exploit phototoxic plants.

The complementary role of plain radiographs and radionuclide shuntography in evaluating CSF-VP shunts.

Cerebrospinal fluid-ventriculoperitoneal shunts are often used in the treatment of hydrocephalus in children. Many complications can arise that may lead to shunt malfunction, including detachment of the distal limb of the shunt. A case is presented where such a complication occurred with distal migration of the detached tubing into the abdomen, which resulted in a patent subcutaneous tract through which cerebrospinal fluid could drain. The need for radiographic correlation at the time of radionuclide shuntography is stressed.

Biliary obstruction after cholecystectomy: diagnosis with quantitative cholescintigraphy.

Fifty patients with recurrent post-cholecystectomy pain underwent hepatobiliary scintigraphy. Time-activity curves were generated from regions of interest over the liver, bile duct, duodenum, and bowel. Patients were divided into obstructed and unobstructed groups with endoscopic retrograde cholangiopancreatography criteria. Measurements from the liver, duodenum, and bowel curves contributed little to the analysis. The washout phase of the bile duct curve showed intermittent emptying in both obstructed and unobstructed groups. Less than one-third of peak activity remained in both groups at 90 minutes. Retention fell more rapidly in the later portion of the sequence in patients with obstruction. Quantification was essential, since differences were subtle and could not be appreciated visually. In the absence of hepatocellular disease, the most reliable criterion was the time at which maximal bile duct activity occurred. A cutoff level of 29 minutes or more was used in the diagnosis of obstruction. A sensitivity of 93% with an adequate specificity of 64% and an overall accuracy of 80% was achieved in the prediction of obstruction.

Smoking behavior and the efficacy of nurses as role models.

The smoking cessation and prevention issue has not been addressed by nurses, the largest group of health care professionals in the nation (1.4 million currently licensed to practice). The World Health Organization and the Centers for Disease Control acknowledge smoking as the "single most preventable cause of poor health in the world," but not a solitary continuing medical education course of the 9,000 available in the United States in 1983 dealt with ways to resolve this issue. The women's movement has not addressed this cause, and nurses, a predominantly female population, continue to smoke in alarmingly large numbers, causing doubt as to nurses' effectiveness n teaching prevention or cessation. Nurses as role models could be crucial in effecting change in the smoking behavior of the general population, thereby eliminating or greatly reducing the health risk. There appears to be a significant need for more effective educational programs concerning the health hazards of smoking for all nurses and nursing students if the potential power of nursing leadership is to be realized in reducing mortality and morbidity from the number one killer in America.

Evidence for an inhibitory role of cyclic AMP in the control of juvenile hormone biosynthesis by cockroach corpora allata.

High levels of cyclic AMP were found in the corpora allata of adult female Diploptera punctata. The adenylate cyclase activator forskolin caused a rapid, reversible and dose-dependent accumulation of cAMP in the corpora allata in vitro. The sensitivity of the corpora allata to forskolin was low when juvenile hormone (JH) synthetic activity was high, and vice versa. Incubation of corpora allata with compounds which cause or mimic elevated intracellular cAMP levels (forskolin, 3-isobutyl-1-methylxanthine, 8-bromo-cAMP) led to a rapid and dose-dependent inhibition of juvenile hormone synthesis. Glands from day 5 virgin females were more sensitive to forskolin than glands from mated females of the same age. The results suggest that a cAMP second messenger system may be responsible for the intracellular transduction of inhibitory signals to the corpora allata of D. punctata.

Hospital readmissions among survivors six months after myocardial revascularization.

One neglected but important measure of early morbidity after coronary artery bypass graft (CABG) operations is rehospitalization. As part of a prospective study of recovery after elective CABG procedures conducted at four academic medical centers, data from all readmissions occurring within the first six postoperative months were collected for 326 patients. A total of 24% of patients had readmissions. The most common categories of readmission discharge diagnoses were cardiac (57%), noncardiac (26%), and surgical sequelae (17%). Factors from the initial hospitalization identified as risk factors for rehospitalization included: length of stay in intensive care unit after surgery, severe noncardiac complications, duration of preoperative cardiac symptoms, intra-aortic balloon insertion, and preoperative resting angina. These findings help to identify a subset of at risk patients for whom more careful surveillance might be beneficial.