The effect of hepatocyte enlargement on the hemodynamic characteristics of the isolated perfused rat liver preparation

The influence of hepatocyte enlargement on intrahepatic hemodynamics was assessed in the isolated perfused rat liver preparation (IPRL) using two experimental models: hypotonic liver cell swelling and phenobarbitone-induced hepatocyte hypertrophy. The analysis of pressure-flow data obtained from the portal vascular bed over a flow range of 0 to 70 mL/min in the presence of a maximally-effective concentration of the vasodilator agent papaverine hydrochloride (6 x 10(-4) mol/L) enabled the calculation of P0, an estimate of the pressure required to passively distend the intrahepatic vasculature, and Gmax, the maximal portal vascular conductance. By comparison with an isotonic perfusion medium (Krebs-Henseleit buffer [KH] containing 2.5% bovine serum albumin [BSA]), perfusion with a hypotonic medium induced a significant increase in mean hepatocyte cross-sectional area (H(A)) (590 +/- 21 vs. 324 +/- 23 microm(-2), p < .05), a fall in Gmax (0.39 +/- 0.08 vs. 2.02 +/- 0.18 mL/min/g/mm hg, P < .001), and an increase in P0 (2.96 +/- 0.38 vs. 1.58 +/- 0.07 mm hg, P < .001). Phenobarbitone administered in drinking water (0.5 g/L) over a period of 60 days also induced a significant degree of hepatocyte enlargement (HA, 510 +/- 29 microm2, P < .05). On day 7, portal pressure measured in vivo in this group was significantly elevated compared with untreated controls (10.5 +/- 0.3 vs. 8.4 +/- 0.2 mm hg, P < .001), while in the IPRL Gmax was reduced (0.48 +/- 0.01 mL/min/g/mm hg, P < .001), and P0 was increased (2.23 +/- 0.17 mm hg, P < .05). However, with continued phenobarbitone treatment portal pressure, Gmax and P0 returned toward control values. The results confirm that hepatocyte enlargement is associated with a significant disturbance of intrahepatic hemodynamics but also that some adaptation occurs if hepatocyte enlargement is sustained over a prolonged period of time.     

Study of the phlebotomines (Diptera, Psychodidae), in area of cutaneous leishmaniasis in the State of Mato Grosso do Sul, Brazil

Interleukin-1 beta (IL-1 beta) significantly inhibits insulin secretion from glucose stimulated islet cells. The mechanism for this inhibition has been hypothesized to be due to stimulation of the inducible form of nitric oxide synthase and a resulting increase in nitric oxide (NO) concentration. Ways to block the effect of IL-1 beta have focused on blocking the binding of IL-1 beta to the IL-1 receptor and the use of antioxidants to neutralize increases in NO. This report focuses on a 33 residue peptide synthesized based on the C-terminal region of the IL-1 beta molecule, a reported binding site of the IL-1 beta molecule, and the redoxcycling antioxidant pyrroloquinoline quinone (PQQ). The 33 residue peptide did not function as an antagonist, but as a weak agonist. High concentrations of PQQ itself inhibited glucose-dependent insulin release while low concentrations did not. PQQ had no effect on the actions of IL-1 beta. Three isosteric and isomeric analogues of PQQ were also investigated. One of the PQQ isomers had an inhibitory effect on insulin secretion at low concentrations where PQQ had no effect. These results reflect the sensitivity of islets to oxidative stress.     

Auditory evoked potentials during multichannel selective listening: role of pitch and localization cues

Auditory evoked potentials were recorded from subjects who listened selectively to tone pips arriving over one of three input channels. Their task was to detect occasional target tones of a slightly longer duration. In different runs the three channels were distinguished from one another by (a) pitch cues alone (800, 1,800, and 2,800 Hz), (b) localization cues alone (right ear, midline, ane left ear), and (c) both of these cues conjointly. In all three conditions the direction of attention was reflected in the amplitude of the N1 wave of the evoked potential, which was selectively enhanced to tones in the attended channel; tones in the central channels in the single-cue conditions, however, produced the least N1 lability and were the least discriminable. The N1 wave was interpreted as a sign of an initial stimulus set or filtering mode of selective attention, whereas a subsequent P3 wave was specifically associated with detections of the target stimuli.     

Effectiveness of external decompression of the biliary tract in middle-aged and old persons with cholecystitis

It was shown that parenteral administration of lead ions caused in the blood serum of albino mice a significant decrease in the amount of the bound RNA-ase 1 inhibitor and a simultaneous increase in the activity of this enzyme. Consequently, this inhibitor served as a regulator of the serum RNA-ase 1 activity. A considerable increase in the amount of the bound and free RNA-ase 1 inhibitor was noted in the serum in the process of triple immunization of persons with live influenza vaccine; this was accompanied by a significant reduction of the free RNA-ase 1 activity. This indicated that along with other mechanisms the inhibitor apparently participated in the processes of formation of immunity against influenza.     

Mark and recapture of adult Ixodes pacificus (Acari: Ixodidae) to determine the effect of repeated removal sampling on tick abundance

The effect of biweekly flagging on adult Ixodes pacificus Cooley & Kohls abundance was determined by using mark-recapture techniques. Ticks were recaptured up to three times during the 12-wk study, and increasingly higher proportions of marked ticks were recaptured as the study progressed. By week 6 of the study, 46% of the collected ticks had been marked, and on the final sampling date, all ticks had been captured previously. Removal sampling would have substantially reduced estimates of the abundance of the questing I. pacificus adult population. For ecological studies that require the repeated sampling of a given habitat, the most representative data are obtained by returning flagged ticks to their collection site.     

Varicella during pregnancy. Maternal and fetal effects

To determine the characteristics of maternal varicella at our institution, we reviewed all cases of primary varicella in pregnancy. Using a perinatal database that summarizes all obstetric admissions, we reviewed the medical records of women with varicella infections during pregnancy. Over a 5 1/2-year period, 31 pregnancies were affected by varicella infection among 11,753 deliveries. The mean age of those patients was 19.6 years, significantly different from our overall population of 25.3 years (P < .05). The racial composition of 35% Hispanic, 35% white, and 29% African American was different from that of our general population of 55% white, 38% African American, and 6% Hispanic (P = .023). The mean gestational age of the eruption of vesicles was 25 weeks. Of the 31 women, 7 had preterm labor within a week of their varicella, 3 delivered prematurely, and 3 infants had a birth weight of less than 2,700 grams. Respiratory symptoms developed in 6 women, and pneumonia developed in 4, 2 of whom required ventilatory support, 1 for 5 days, the other for 49 days. Eight women received acyclovir during gestation, and none suffered sequelae. In all, 6 infants had lesions and anomalies noted at birth, 5 possibly associated with varicella. Varicella infection is associated with a greater-than-expected level of both maternal and fetal morbidity. The fetal disease may occur due to maternal infection at any gestation and is most likely a spectrum of complications. The maternal disease appears to be worse in the latter half of pregnancy. Programs of prevention through vaccination must account for a possibly decreased level of immunity in different populations.     

Partial activation of CD8+ T cells by a self-derived peptide

T cells are normally activated when the peptide for which they are specific is presented to them in the context of the appropriate major histocompatibility complex (MHC) (class I and Class II for CD8+ and CD4+ T cells, respectively). An increasing body of evidence indicates that structural homologues of the immunogenic peptide can partially activate or antagonize CD4+ T cells. CD8+ T cells may also be partially antagonized by such peptides, and self-derived peptides of this type may play a role in CD8+ T cell selection in the thymus. Activated CD8+ T cells lyse their targets by perforin-dependent granule exocytosis and by inducing apoptosis mediated by CD95 (also known as Fas or APO1) with its ligand (CD95L). Here we show that a clone of Kd-restricted CD8+ T cells specific for influenza haemagglutinin, which can also be activated in a crossreactive manner by a peptide derived from a myeloma tumour immunoglobulin heavy-chain variable region (IgVH) to kill by both routes, kills only by the CD95-CD95L pathway when stimulated by the corresponding germline IgVH peptide. As this germline IgVH peptide differs from the tumour peptide only at a single position buried in the MHC-binding groove, this indicates that CD95-CD95L-mediated killing can be triggered independently of the perforin-mediated pathway, and can be selectively affected by changes in MHC conformation.     

A comparison of two methods to teach smoking-cessation techniques to medical students

PURPOSE: To evaluate two smoking-cessation practice exercises, one using standardized patients (SPs), the other using role playing by medical students. METHOD: In the spring of 1994 all 120 first-year University of California, San Francisco, School of Medicine Students were given lectures on the health effects of smoking and how physicians can help patients quit. Afterward some of the students were randomly assigned to two groups in which to practice counseling patients: Group 1 (n = 35) used SPs, Group 2 (n = 37) used role playing. Each of the Group 1 students practiced smoking-cessation techniques with an SP; the SP evaluated the student on cognitive and communication skills, assigned an overall rating, and provide feedback using a standardized form. The Group 2 students (as well as the 48 students not assigned to a group) role-played in pairs and used the same form to provide feedback. All the students evaluated their respective practice practices. Two weeks later 24 Group 1 and 31 Group 2 students participated in a clinic-skills-assessment exercise using SPs. As in the Group 1 practice exercise, each student was evaluated by an SP on cognitive and communication skills and assigned an overall rating. Data were analyzed through a number of statistical methods. The cost of the SP program was determined. RESULTS: The Group 1 students rated their practice exercise much more favorably than did the Group 2 students. However, there was no significant difference between the groups in their ratings by the SPs on the clinical-skills-assessment exercise. The use of SPs cost a great deal more than did the use of role playing. CONCLUSION: Although the students rated the SPs higher than they did the role playing, the two tools produced similar levels of skills attainment. The data suggest that having students practice smoking-cessation techniques through role playing may be as effective as using the more extensive SPs.