End-of-life care in the pediatric intensive care unit: Attitudes and practices of pediatric critical care physicians and nurses

OBJECTIVE

To determine the attitudes and practices of pediatric critical care attending physicians and pediatric critical care nurses on end-of-life care.

DESIGN

Cross-sectional survey.

SETTING

A random sample of clinicians at 31 pediatric hospitals in the United States.

MEASUREMENTS AND MAIN RESULTS

The survey was completed by 110/130 (85%) physicians and 92/130 (71%) nurses. The statement that withholding and withdrawing life support is unethical was not endorsed by any of the physicians or nurses. More physicians (78%) than nurses (57%) agreed or strongly agreed that withholding and withdrawing are ethically the same (p < .001). Physicians were more likely than nurses to report that families are well informed about the advantages and limitations of further therapy (99% vs. 89%; p < .003); that ethical issues are discussed well within the team (92% vs. 59%; p < .0003), and that ethical issues are discussed well with the family (91% vs. 79%; p < .0002). On multivariable analyses, fewer years of practice in pediatric critical care was the only clinician characteristic associated with attitudes on end-of-life care dissimilar to the consensus positions reached by national medical and nursing organizations on these issues. There was no association between clinician characteristics such as their political or religious affiliation, practice-related variables such as the size of their intensive care unit or the presence of residents and fellows, and particular attitudes about end-of-life care.

CONCLUSIONS

Nearly two-thirds of pediatric critical care physicians and nurses express views on end-of-life care in strong agreement with consensus positions on these issues adopted by national professional organizations. Clinicians with fewer years of pediatric critical care practice are less likely to agree with this consensus. Compared with physicians, nurses are significantly less likely to agree that families are well informed and ethical issues are well discussed when assessing actual practice in their intensive care unit. More collaborative education and regular case review on bioethical issues are needed as part of standard practice in the intensive care unit.

The effect of depositional history on contaminated bed sediment stability

Experiments were conducted in an annular flume using a commercially available kaolinite clay as well as contaminated bed sediment from Hamilton Harbour (Ontario) to assess their stability against erosion. Critical shear stress for erosion was measured under different conditions of bed formation (quiescently deposited beds and shear deposited beds) as well as with and without the presence of a biostabilized bed. Results suggest that a biostabilized bed and a bed formed under a flowing condition, similar to a river scenario, will be more resistant against erosion than will a non-biostabilized bed and a bed formed under quiescent conditions. Up to three cycles of erosion and flocculation/deposition were observed to occur within one experiment. These results suggest that the depositional history and biostabilization of river bed sediments need to be seriously considered within sediment and contaminant transport models if meaningful estimates of sediment and contaminant source, fate and effect are to be generated and used for the management of our aquatic ecosystems.

Progressive reduction in treatment-related deaths in Medical Research Council childhood lymphoblastic leukaemia trials from 1980 to 1997 (UKALL VIII, X and XI)

In the last 20 years, the survival rate for children with acute lymphoblastic leukaemia (ALL) has markedly improved, largely owing to a decrease in relapses. However, children still die from complications of treatment and these are potentially preventable. We have analysed data from three large consecutive national protocols for ALL from 1980 to 1997 [Medical Research Council United Kingdom ALL (MRC UKALL) trials VIII, X and XI] to compare the incidence and causes of treatment-related deaths (TRD). The percentage of TRD has fallen from 9% to 2% (UKALL VIII to XI), largely as a result of a decrease in fatal infections. Deaths during induction have fallen from 3% to 1%, the main causes of death being bacterial, followed by fungal infection, while other causes, chiefly haemorrhage, have not declined. Remission deaths also decreased from 6% to 1%, particularly those deaths due to measles and pneumocystis carinii. More guidelines for surveillance and treatment of infections have been included within progressively more intensive protocols. Risk factor analysis showed increased TRD in patients with Down's syndrome, high leucocyte count and older age in UKALL XI. In contrast, the introduction of blocks of intensification was not associated with an increased death rate. While improved supportive care has reduced the incidence of TRD, there is still scope for further reduction by prompt treatment of suspected infection. Maintenance of herd immunity remains of vital importance in avoiding deaths from measles.

Fas/CD95 pathway induces mouse liver regeneration and allows for highly efficient retrovirus-mediated gene transfer

Stable gene transfer into hepatocytes has been proposed to compensate for genetic deficiencies that affect liver function, or to deliver diffusible factors into the circulation. This strategy can be achieved using retroviral vectors; however, cell division must occur. We describe a simple and reproductive method that enables the induction of hepatocyte replication in a controlled fashion, thus allowing an efficient in vivo retroviral liver transduction that is applicable to mouse models of human genetic disorders. The approach is based on liver susceptibility to apoptosis via the Fas/CD95 pathway. We show that, 4 days following a single Fas agonist antibody (JO2) injection, hepatocyte replication occurs, the intensity of which is correlated with the level of the induced hepatic cytolysis. This treatment enables in vivo liver transduction, and its efficiency also correlates with the level of hepatic cytolysis. When recombinant retroviral vectors were infused intravenously during the period of hepatocyte replication, 15.4% +/- 1.7% of the hepatocytes were transduced, reaching up to 32.5%.

A randomized, double-blind study of triple nucleoside therapy of abacavir, lamivudine, and zidovudine versus lamivudine and zidovudine in previously treated human immunodeficiency virus type 1-infected children. The CNAA3006 Study Team

OBJECTIVES

Abacavir (ABC) is a potent inhibitor of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase. We compared the efficacy, safety, and tolerability of combination therapy with ABC, lamivudine (3TC), and zidovudine (ZDV) versus 3TC and ZDV in antiretroviral experienced HIV-1-infected children over 48 weeks.

METHODS

Two hundred five HIV-1-infected children who had received previous antiretroviral therapy and had CD4(+) cell counts >/=100 cells/mm(3) were stratified by age and by previous treatment. Participants were randomly assigned to receive ABC (8 mg/kg twice daily [BID]) plus 3TC (4 mg/kg BID) and ZDV (180 mg/m(2) BID; ABC/3TC/ZDV group) or ABC placebo plus 3TC (4 mg/kg BID) and ZDV (180 mg/m(2); 3TC/ZDV group). Participants who met a protocol-defined switch criteria (plasma HIV-1 RNA >0.5 log(10) copies/mL above baseline at week 8 or >10 000 copies/mL after week 16) had the option to switch to open-label ABC plus any antiretroviral combination or continue randomized therapy or withdraw from the study.

RESULTS

The Kaplan-Meier estimates (95% confidence interval) of the proportion of participants who maintained HIV-1 RNA levels </=10 000 copies/mL for 48 weeks or more was significantly better in the ABC/3TC/ZDV group compared with the 3TC/ZDV group: 33% (23%-42%) versus 21% (13%-29%). At week 48, the proportions of participants with HIV-1 RNA </=10 000 copies/mL were 36% versus 26% for the ABC/3TC/ZDV and 3TC/ZDV groups, respectively, by intent-to-treat analysis. For the subgroup of participants with baseline HIV-1 RNA >10 000 copies/mL, a significantly higher proportion of participants in the ABC/3TC/ZDV group had HIV-1 RNA </=10 000 copies/mL compared with the 3TC/ZDV group (29% vs 12%) but no difference was observed in the subgroup of participants with baseline HIV-1 RNA </=10 000 copies/mL (78% vs 72%). The median changes from baseline in CD4(+) cell counts were greater in the ABC/3TC/ZDV group than in the 3TC/ZDV group. Few participants (3%) experienced abacavir-related hypersensitivity reaction.

CONCLUSIONS

ABC, in combination with 3TC and ZDV, provides additional antiretroviral activity over 48 weeks, compared with combination therapy with 3TC and ZDV in antiretroviral experienced HIV-1-infected children. ABC was safe and generally well-tolerated and should be considered an active component of combination antiretroviral therapy in this pediatric population.

The Andro Project: physiological and hormonal influences of androstenedione supplementation in men 35 to 65 years old participating in a high-intensity resistance training program

BACKGROUND

Since the passage of The Dietary Supplement Health and Education Act in 1994, there has been a flood of new "dietary" supplements promoting anti-aging benefits such as the enhancement of growth hormone or testosterone levels. Androstenediol and androstenedione are such products. This study's purpose was to elucidate the physiological and hormonal effects of 200 mg/d of oral androstenediol and androstenedione supplementation in men aged 35 to 65 years while participating in a 12-week high-intensity resistance training program.

METHODS

Fifty men not consuming any androgenic-enhancing substances and with normal total testosterone levels, prostate-specific antigen, hemoglobin, and hematocrit, and with no sign of cardiovascular or metabolic diseases participated. Subjects were randomly assigned to a placebo, androstenediol (diol), or androstenedione (dione) group using a double-blind study design. Main outcomes included serum sex hormone profile, body composition assessment, muscular strength, and blood lipid profiles.

RESULTS

During the 12 weeks of androstenedione or androstenediol use, a significant increase in the aromatization by-products estrone and estradiol was observed in both groups (P =.03). In the dione group, total testosterone levels significantly increased 16% after 1 month of use, but by the end of 12 weeks, they returned to pretreatment levels. This return to baseline levels resulted from increases in aromatization and down-regulation in endogenous testosterone synthesis based on the fact that luteinizing hormone was attenuated 18% to 33% during the treatment period. Neither androstenediol nor androstenedione enhanced the adaptations to resistance training compared with placebo for body composition or muscular strength. However, both androstenediol and androstenedione supplementation adversely affected high-density lipoprotein cholesterol (HDL-C) levels, coronary heart disease risk (representing a 6.5% increase), and each group's respective (low-density lipoprotein cholesterol [LDL-C]/HDL-C)/(apolipoprotein A/apolipoprotein B) lipid ratio (diol: +5.2%; dione: +10.5%; P =.05). In contrast, the placebo group's HDL-C levels increased 5.1%, with a 12.3% decline in the (LDL-C/HDL-C)/(apolipoprotein A/apolipoprotein B) lipid ratio. These negative and positive lipid effects occurred despite no significant alterations in body composition or dietary intakes in the supplemental groups or placebo group, respectively.

CONCLUSIONS

Testosterone precursors do not enhance adaptations to resistance training when consumed in dosages recommended by manufacturers. Testosterone precursor supplementation does result in significant increases in estrogen-related compounds, dehydroepiandrosterone sulfate concentrations, down-regulation in testosterone synthesis, and unfavorable alterations in blood lipid and coronary heart disease risk profiles of men aged 35 to 65 years.

Health benefits achieved through the Seventh-Day Adventist Wellness Challenge program

CONTEXT

The Wellness Challenge program introduces the philosophy of the healing power of God and stresses the importance of developing a sense of spirituality in conjunction with the promotion of good health.

OBJECTIVE

To employ scientific rigor to the outcome measures of the Seventh-Day Adventist Wellness Challenge program.

DESIGN

A 2-tailed, paired sample t test.

SETTING

East Pasco Medical Center in Zephyrhills, Fla.

PARTICIPANTS

165 participants.

INTERVENTION

Presurvey, 21-day outpatient wellness intervention; postsurvey, 6 weeks after completion of the program.

MAIN OUTCOME MEASURES

Changes in behaviors related to cigarette smoking, alcohol use, eating patterns, exercise, water consumption, rest, relaxation, and time spent outdoors, as well as demographic data.

RESULTS

Statistically significant differences were found between the pre- and postprogram clinical and laboratory test results for the participants' blood pressure, weight, glucose levels, and cholesterol at .05 alpha. Furthermore, self-health improvements measured by a pre- and postsurvey response confirmed statistically significant improvement in participants' willingness to improve their lifestyle behaviors for a potentially greater quality of life.

CONCLUSION

The Wellness Challenge program offers ways to reduce risk factors related to chronic disease while improving the quality of life within an adult population by allowing people to slowly incorporate newly acquired tools into their everyday life.

A preclinical model of hepatocyte gene transfer: the in vivo, in situ perfused rat liver

Delivering retroviruses targeted to hepatocytes in vivo involves the injection of retroviruses directly into the portal vein. The aim of this work was to establish a clinically relevant system for retrovirus-mediated gene transfer in a new model of in vivo, in situ perfused rat liver and to study the transgene expression. At 24 h after partial hepatectomy, the liver was completely excluded from the splanchnic circulation using an extracorporeal shunt. Two independent normothermal, oxygenated perfusion systems were used. First, liver perfusion was carried out with a recirculating system (1 h). Culture supernatant containing retroviruses (1.5 x 10(8) ffu/ml, beta-galactosidase gene) was used as perfusate. Then the liver perfusion was maintained for more 30 min in a single liver passage system using culture medium without retroviruses as perfusate. High hepatocyte transduction rates (up to 34.4%) were obtained. PCR analysis showed no provirus in extrahepatic organs. Viral titrations performed simultaneously (inflow and outflow liver lines) showed that after 1 h of perfusion (up to 30 successive liver passages) retroviruses were still detected in the liver outflow perfusate (up to 2.0 x 10(7) ffu/ml). Washing the liver for 30 min dramatically decreased the leakage of retroviruses in the outflow. In order to be of clinical use, the injection of retroviruses targeted to hepatocytes in vivo should be done while the liver is completely excluded from the splanchnic circulation to avoid any extrahepatic retrovirus diffusion.

The treatment of Wilms' tumour: results of the United Kingdom Children's cancer study group (UKCCSG) second Wilms' tumour study

The aims of the UKW2 study were: (1) to further refine treatment for stage I and II favourable histology (FH) patients; (2) to consolidate the UKW1 results for stage III FH patients; (3) to improve the outlook for patients with inoperable primary tumours and those patients with stage IV and unfavourable histology disease. Treatment consisted of primary nephrectomy, wherever possible, followed by chemotherapy and radiotherapy, as dictated by stage and histology. Treatment was refined successfully for stage I and II FH patients. The 4-year event-free survival for these two groups was 94% and 91%, respectively. Stage III FH patients had a 4-year event free survival of 84%. The outlook for patients with clear cell sarcoma of the kidney is as good as for patients with favourable histology, whilst that for patients with anaplastic or rhabdoid variants remains poor. The outlook for the majority of children with Wilms' tumour is now excellent.

Relationships between environmental factors and lung function of asthmatic subjects in south east Queensland, Australia

Few panel studies have investigated the relationships between air pollutants and air spora and lung function change in asthmatic subjects. This article examines the association of outdoor air pollutant concentrations and air spora with the decrease in lung function (measured by morning peak expiratory flow) of two groups of asthmatic subjects in the subtropical environment of South East Queensland, Australia. Lung function responses were stratified by age, allergy status, and location, and seasonal effects were examined. Allergy status and age were found to be important, with air pollutants such as ozone and particles associated with decreases in lung function in allergic individuals older than 15 years. Fungal spore counts were strongly associated with a decrease in lung function in allergic adults, especially in those over 54 years, only in seasons when these air spora peak. Analysis for the entire study period indicates that the effect of ozone on peak expiratory flow in the allergic group can sometimes be confounded by air spora effects, indicating that in a subtropical climate the impact of ozone on asthma severity can be accurately estimated only when the confounding effects of air spora are included.

End-of-life care in the pediatric intensive care unit after the forgoing of life-sustaining treatment

OBJECTIVE

To describe the attitudes and practice of clinicians in providing sedation and analgesia to dying patients as life-sustaining treatment is withdrawn.

STUDY DESIGN

Prospective case series of 53 consecutive patients who died after the withdrawal of life-sustaining treatment in the pediatric intensive care unit at three teaching hospitals in Boston. Data on the reasons why medications were given were obtained from a self-administered anonymous questionnaire completed by the critical care physician and nurse for each case. Data on what medications were given were obtained from a review of the medical record.

RESULTS

Sedatives and/or analgesics were administered to 47 (89%) patients who died after the withdrawal of life-sustaining treatment. Patients who were comatose were less likely to receive these medications. Physicians and nurses cited treatment of pain, anxiety, and air hunger as the most common reasons, and hastening death as the least common reason, for administration of these medications. Hastening death was viewed as an "acceptable, unintended side effect" of terminal care by 91% of physician-nurse matched pairs. The mean dose of sedatives and analgesics administered nearly doubled as life-support was withdrawn, and the degree of escalation in dose did not correlate with clinician's views on hastening death.

CONCLUSION

Clinicians frequently escalate the dose of sedatives or analgesics to dying patients as life-sustaining treatment is withdrawn, citing patient-centered reasons as their principle justification. Hastening death is seen as an unintended consequence of appropriate care. A large majority of physicians and nurses agreed with patient management and were satisfied with the care provided. Care of the dying patient after the forgoing of life-sustaining treatment remains underanalyzed and needs more rigorous examination by the critical care community.

Therapeutic liver repopulation in a mouse model of hypercholesterolemia

Liver repopulation constitutes an attractive approach for the treatment of liver disorders or of diseases requiring abundant secretion of an active protein. We have described previously a model of selective repopulation of a normal liver by Fas/CD95-resistant hepatocytes, in which we achieved up to 16% hepatocyte repopulation. In the present study, we investigated the therapeutic efficacy of this strategy. With this aim, apolipoprotein E (ApoE) knockout mice were transplanted with Fas/CD95-resistant hepatocytes which constitutively express ApoE. Transplanted mice were submitted to weekly injections of non-lethal doses of the Fas agonist antibody Jo2. After 8 weeks of treatment, we obtained up to 30% of the normal level of plasma ApoE. ApoE secretion was accompanied by a drastic and significant decrease in total plasma cholesterol, which even fell to normal levels. Moreover, this secretion was sufficient to markedly reduce the progression of atherosclerosis. These results demonstrate the efficacy of this repopulation approach for correcting a deficiency in a protein secreted by the liver.

Vasopressin-mediated regulation of epithelial sodium channel abundance in rat kidney

Sodium transport is increased by vasopressin in the cortical collecting ducts of rats and rabbits. Here we investigate, by quantitative immunoblotting, the effects of vasopressin on abundances of the epithelial sodium channel (ENaC) subunits (alpha, beta, and gamma) in rat kidney. Seven-day infusion of 1-deamino-[8-D-arginine]-vasopressin (dDAVP) to Brattleboro rats markedly increased whole kidney abundances of beta- and gamma-ENaC (to 238% and 288% of vehicle, respectively), whereas alpha-ENaC was more modestly, yet significantly, increased (to 142% of vehicle). Similarly, 7-day water restriction in Sprague-Dawley rats resulted in significantly increased abundances of beta- and gamma- but no significant change in alpha-ENaC. Acute administration of dDAVP (2 nmol) to Brattleboro rats resulted in modest, but significant, increases in abundance for all ENaC subunits, within 1 h. In conclusion, all three subunits of ENaC are upregulated by vasopressin with temporal and regional differences. These changes are too slow to play a major role in the short-term action of vasopressin to stimulate sodium reabsorption in the collecting duct. Long-term increases in ENaC abundance should add to the short-term regulatory mechanisms (undefined in this study) to enhance sodium transport in the renal collecting duct.

Joint liaison psychiatry-diabetes clinic: a new specialist service

AIMS

Specialist diabetes clinics have an established role in prevention and management of complications. As psychological problems are usually treated separately from diabetes centres, the role of a specialist psychiatrist within a teaching hospital was assessed. The aims of the study were to describe referral patterns, specific psychiatric conditions and treatments offered.

RESULTS

During weekly outpatient sessions over a 12-month period, 31 patients were referred with a wide range of psychiatric diagnoses. One-third of patients were seen on the day and two-thirds within 2 weeks of referral. Treatments included anti-depressant medication, counselling and cognitive behaviour therapy. Successful discharge was obtained in 10 subjects and eight were undergoing continued treatment.

CONCLUSIONS

The range of specific diagnoses requiring psychiatric supervision supported the role of specifically trained personnel as seen in a joint liaison psychiatry-diabetes service.

Toxicity of nitrogen oxides and related oxidants on mycobacteria: M. tuberculosis is resistant to peroxynitrite anion

OBJECTIVE

To test the toxicity of reactive nitrogen intermediates (RNI), including authentic nitric oxide (NO), nitrogen dioxide (NO2), and peroxynitrite anion (ONOO-), a potent oxidant derived from NO and superoxide anion, on various mycobacterial strains including M. tuberculosis.

DESIGN

Relatively avirulent mycobacteria including M. smegmatis and BCG, as well as the pathogenic M. Bovis Ravenel and M. tuberculosis Erdman and the clinical isolate M160 (also known as the C strain) were tested for their susceptibility to the toxic effects of NO, NO2, and ONOO-, Deaerated, NO-saturated solutions as well as an anaerobic in vitro system in which mycobacteria can be exposed to desired concentrations of authentic NO or NO2, were employed in these studies. An in vitro ONOO- killing assay was used to examine the adverse effects of this NO-derived oxidant on the various strains of mycobacteria.

RESULTS

Both NO and NO2 exhibit antimycobacterial activity, with the former being more potent. Results obtained using ONOO- killing assay revealed that while avirulent mycobacteria including BCG and M. smegmatis are susceptible to this NO-derived oxidant, the virulent Erdman strain of M. tuberculosis and M. bovis, as well as the clinical tuberculous isolate M160, are remarkably resistant.

CONCLUSION

These results suggest that the interactions between RNI and various species of mycobacteria could be highly specific. And since activated macrophages produce peroxynitrite, the significance of the ONOO- resistance of M. tuberculosis strains in relation to intracellular survival deserves further investigation.

Benefit of intensified treatment for all children with acute lymphoblastic leukaemia: results from MRC UKALL XI and MRC ALL97 randomised trials. UK Medical Research Council's Working Party on Childhood Leukaemia

Treatment of children with acute lymphoblastic leukaemia (ALL) aims to cure all patients with as little toxicity as possible and, if possible, to restrict further intensification of chemotherapy to patients with an increased risk of relapse. However in Medical Research Council (MRC) trial UKALL X two short myeloablative blocks of intensification therapy given at weeks 5 and 20 were of benefit to children in all risk groups. The successor trials, MRC UKALL XI and MRC ALL97, tested whether further intensification would continue to benefit all patients by randomising them to receive, or not, an extended third intensification block at week 35. After a median follow-up of 4 years (range 5 months to 8 years), 5 year projected event-free survival was superior at 68% for the 894 patients allocated a third intensification compared with 60% for the 887 patients who did not receive one (odds ratio 0.75, 95% CI 0.63-0.90, 2P = 0.002). This difference was almost entirely due to a reduced incidence of bone marrow relapses in the third intensification arm (140 of 891 in the third intensification arm vs. 171 of 883 in the no third intensification, 2P = 0.02). Subgroup analysis suggests benefit of the third intensification for all risk categories. Overall survival to date is no different in the two arms, indicating that a greater proportion of those not receiving a third intensification arm and subsequently relapsing can be salvaged. These results indicate that there is benefit of additional intensification for all risk subgroups of childhood ALL.

Autopsy consent practice at US teaching hospitals: results of a national survey

BACKGROUND

Autopsy rates continue to fall despite the enduring benefit of the procedure to families and medical science, yet there are few data about the consent process itself.

OBJECTIVE

To evaluate the current practice of obtaining autopsy consent, by assessing the consent forms currently in use, the knowledge and attitudes of chief residents on the procedure, and the expert opinion of pathologists in those institutions.

DESIGN

Cross-sectional survey.

SETTINGS AND PARTICIPANTS

One hundred twenty-seven US teaching hospitals.

RESULTS

Of all autopsy consent forms we surveyed, 84.7% contained 7 of 10 elements recommended by the College of American Pathologists. Only 7.1% of institutions supplied educational materials for the physician, as recommended by the College of American Pathologists. Overall, 50.1% of chief residents reported deficiencies in their knowledge of the autopsy procedure. Correspondingly, greater than 74.5% felt that educational materials would be beneficial for physicians and the family. Finally, 93.3% of chief residents believed that a limited autopsy should be offered to families, while 68 (90%) of 76 pathologists at these institutions believed that limited autopsies are an unsatisfactory alternative to the complete procedure.

CONCLUSIONS

Chief residents at US teaching hospitals reported substantial deficiencies in their knowledge about autopsy and desire more training on the consent process. Autopsy consent forms are often lacking information that might help physicians and families in making an educated choice about autopsy. Teaching institutions need to reevaluate the training for the autopsy consent practice.

UT-A2: a 55-kDa urea transporter in thin descending limb whose abundance is regulated by vasopressin

The renal urea transporter gene (UT-A) produces different transcripts in the inner medullary collecting ducts (UT-A1) and thin descending limbs of Henle's loop (UT-A2), coding for distinct proteins. Peptide-directed rabbit polyclonal antibodies were used to identify the UT-A2 protein in renal medulla of mouse and rat. In the inner stripe of outer medulla, an antibody directed to the COOH terminus of UT-A recognized a membrane protein of 55 kDa. The abundance of this 55-kDa protein was strongly increased in response to chronic infusion of the vasopressin analog 1-deamino-[8-D-arginine]vasopressin (DDAVP) in Brattleboro rats, consistent with previous evidence that UT-A2 mRNA abundance is markedly increased. Immunofluorescence labeling with the COOH-terminal antibody in Brattleboro rats revealed labeling in the lower portion of descending limbs from short-looped nephrons (in the aquaporin-1-negative portion of this segment). This UT-A labeling was increased in response to DDAVP. Increased labeling was also seen in descending limbs of long-looped nephrons in the base of the inner medulla. These results indicate that UT-A2 is expressed as a 55-kDa protein in portions of the thin descending limbs of Henle's loop and that the abundance of this protein is strongly upregulated by vasopressin.

Risk factors for hepatitis C transmission in the Victorian population: a telephone survey

OBJECTIVE

To measure knowledge and prevalences of risk factors for hepatitis C infection in the Victorian community.

METHOD

Telephone survey of 757 Victorian householders aged 15+ years, March 1996.

RESULTS

An estimated 2.2% of Victorians have injected illicit drugs; 4.8% have tattoos and 49.6% have skin piercings; 11.4% received a blood transfusion before screening for HCV was introduced; 10.9% have had a test for HCV antibody. A majority of respondents perceived sexual contact and receipt of a transfusion to be risks for HCV transmission.

CONCLUSIONS

Risk factors associated with the spread of HCV are widespread in the Victorian community; however, the most important risk factor--injecting drug use--has low prevalence. Considerable uncertainty exists about risk factors for hepatitis C.

IMPLICATIONS

A very small percentage of Victorians are injecting drug users and therefore at highest risk of hepatitis C infection, therefore transmission control programs can be efficiently focused on this group. The Victorian community needs to be better educated about risk factors for hepatitis C, in particular that transfusions and blood donations are safe.

Aldosterone-mediated regulation of ENaC alpha, beta, and gamma subunit proteins in rat kidney

Aldosterone stimulates sodium transport in the renal collecting duct by activating the epithelial sodium channel (ENaC). To investigate the basis of this effect, we have developed a novel set of rabbit polyclonal antibodies to the 3 subunits of ENaC and have determined the abundance and distribution of ENaC subunits in the principal cells of the rat renal collecting duct. Elevated circulating aldosterone (due to either dietary NaCl restriction or aldosterone infusion) markedly increased the abundance of alphaENaC protein without increasing the abundance of the beta and gamma subunits. Thus, alphaENaC is selectively induced by aldosterone. In addition, immunofluorescence immunolocalization showed a striking redistribution in ENaC labeling to the apical region of the collecting duct principal cells. Finally, aldosterone induced a shift in molecular weight of gammaENaC from 85 kDa to 70 kDa, consistent with physiological proteolytic clipping of the extracellular loop as postulated previously. Thus, at the protein level, the response of ENaC to aldosterone stimulation is heterogenous, with both quantitative and qualitative changes that can explain observed increases in ENaC-mediated sodium transport.

The relation between meal size and the time between meals: effects of cage complexity and food cost

Certain popular models of the regulation of food intake predict a positive correlation between the size of a meal and the preceding and/or following intermeal interval. However, the reported strength of these prandial correlations has varied widely in the literature. To determine what factors may influence the strength of these relationships, we measured the timing of and amount consumed in meals of laboratory rats as a function of 1) whether they were housed in isolation or with partial access to peers or a running wheel, 2) whether they were disturbed daily or weekly for maintenance procedures, and 3) whether food was free or contingent on operant responding. We also compared two definitions of "meal" and "intermeal interval." Strong prandial correlations were found only occasionally. Caging, food cost, and maintenance frequency did not affect the size of the correlations, although these factors did influence the rats' meal patterns. We conclude the regulation of food intake cannot be explained by models relying on a regular relationship between meal size and intermeal interval.