Effects of polyethylene on macrophages

A system was developed to expose macrophages to polyethylene in vitro. Exposure of macrophages to these particles in isolation led to the release of tumor necrosis factor alpha and prostaglandin E₂. Exposure of macrophages in co-culture with osteoblasts to polyethylene particles increased the release of prostaglandin E₂ and also led to the release of interleukin-6. Incubation of radiolabelled calvariae with conditioned medium from macrophages exposed to polyethylene particles alone or to particles in co-culture with osteoblasts led to bone resorption reflected by release of ⁴⁵Ca. Incubation with pamidronate was effective in inhibiting resorption stimulated by conditioned medium from macrophages exposed to these particles alone or in co-culture with osteoblasts. This demonstrates that pamidronate, or other bisphosphonates, may be effective in inhibiting bone resorption at the implant/bone interface in association with the macrophage ressponse to particulate polyethylene. Further investigation into the possible use of pamidronate or other bisphosphonates in the treatment of aseptic loosening is warranted.     

Endometriosis in episiotomy scar with anal sphincter involvement

A case of endometriosis in an episiotomy scar with involvement of the external anal sphincter is presented. The clinical, operative, and pathologic findings are reported. The question of etiology and treatment is discussed, and the literature is reviewed. Wide excision of the ectopic endometrial tissue with primary reconstruction of the external sphincter was curative, and the functional result was excellent. It is suggested that this treatment policy should be recommended for these cases.     

Type II sodium channels in spinal cord astrocytes in situ: Immunocytochemical observations

The expression of sodium channel α-subunit isoforms in astrocytes in adult rat spinal cord and optic nerve was examined utilizing immunocytochemical methods with antibodies generated against conserved and subtype-specific sequences of the sodium channel. In adult rat spinal cord, astrocytes within the dorsal and ventral funiculi were immunolabelled with antibody SP20, which recognizes a conserved sequence within sodium channel types I, II, and III. In addition, astrocytes within these spinal cord white matter tracts were immunostained with antibody SP11-II, which recognizes sodium channel type II. Antibodies SP11-I and SP32-III, which are directed against subtype-specific sequences in sodium channel types I and III, respectively, did not label astrocytes in the dorsal and ventral funiculi of the spinal cord. In optic nerves, astrocytes were immunostained with antibody SP20. However, no detectable labelling of cells within the optic nerve was observed with antibodies SP11-I, SP11-II, and SP32-III. These observations demonstrate that sodium channel II is expressed by astrocytes in spinal cord white matter. Moreover, these data suggest that regional factors regulate the level of sodium channel isoform expression in astrocytes.     

Response of lower esophageal contractility to changing concentrations of halothane or isoflurane: A multicenter study

A multiple-center study was performed to determine the relationship between lower esophageal contractility, clinical signs, and anesthetic concentration as expressed by minimum alveolar concentration (MAC). One hundred four American Society of Anesthesiologists Class I through III patients were exposed to isoflurane (with and without nitrous oxide) or halothane in concentrations of 0.5, 1.0, and 1.5 MAC. Heart rate and systolic blood pressure were continuously monitored. Both the amplitude and frequency of spontaneous and provoked lower esophageal contractions were measured in situ by using a 24-F probe equipped with provoking and measuring balloons. Combined results demonstrated statistically significant correlations (P<0.001) between lower esophageal contractility and MAC. Spontaneous lower esophageal contractions decreased from 1.10±0.12 (SEM) contractions per minute (0.5 MAC) to 0.42±0.05 (1 MAC) to 0.18±0.05 (1.5 MAC). Provoked lower esophageal contractility values decreased from 45±4 mm Hg (0.5 MAC) to 29±3 (1 MAC) to 19±2 (1.5 MAC). Heart rate changes did not correlate with MAC, and systolic blood pressure correlated in only one of three centers. Intracenter and intercenter analyses failed to demonstrate a significant relationship between lower esophageal contractility and heart rate or systolic blood pressure. No intracenter differences in either amplitude or frequency of lower esophageal contractions were observed, despite differences in volatile agents, induction techniques and agents, patient populations, and duration of anesthesia. Our studies indicate that lower esophageal contractility may be an indicator of anesthetic depth as reflected by MAC, but further studies are needed to quantify the effects of surgical stimulus, intravenous anesthetics, vasodilators, anticholinergics, calcium channel blockers, beta-adrenergic agonists, and the presence of a nasogastric tube.     

Renin correlates with blood pressure reactivity to stressors

This study examines the relationship between renin levels and physiologic reactivity to stressors. Seventy-five normotensive and mildly hypertensive men were studied on a high salt diet (200 mEq/day Na) and on a low salt diet (10 mEq/day Na). Renin, plasma catecholamines, heart rate, and blood pressure were examined at rest, after standing in place for 8 minutes, and after a brief mathematics task. Renin levels increased in response to the stressor tasks, particularly on the low salt diet. The change in diastolic pressure in response to the stressor tasks was correlated with the change in renin (r = 0.45, p less than 0.001) but not with the change in norepinephrine. The combination of change in renin and norepinephrine levels accounted for 21% of the variance in predicting diastolic pressure reactivity (p less than 0.0015).     

The Alcohol Beverage Warning Label: When Did Knowledge Increase?

This article presents data on the awareness of the alcohol beverage warning label among a sample of 5,169 inner city African-American gravidas seeking prenatal care. While the label law was implemented in November 1989, a significant increase in knowledge of the label did not occur until March 1990. Women who predominantly consumed wine coolers and beer, and those under age 30 were more likely to know about the label than their counterparts.