Effect of Vitamin C Supplementation for Pregnant Smokers on Offspring Airway Function and Wheeze at Age 5 Years: Follow-up of a Randomized Clinical Trial

Importance

Vitamin C supplementation (500 mg/d) for pregnant smokers has been reported to increase offspring airway function as measured by forced expiratory flow (FEF) through age 12 months; however, its effects on airway function at age 5 years remain to be assessed.

Objective

To assess whether vitamin C supplementation in pregnant smokers is associated with increased and/or improved airway function in their offspring at age 5 years and whether vitamin C decreases the occurrence of wheeze.

Design, Setting, and Participants

This study followed up the Vitamin C to Decrease the Effects of Smoking in Pregnancy on Infant Lung Function (VCSIP) double-blind, placebo-controlled randomized clinical trial conducted at 3 centers in the US (in Oregon, Washington, and Indiana) between 2012 and 2016. Investigators and participants remain unaware of the treatment assignments. Forced expiratory flow measurements at age 5 years were completed from 2018 to 2021.

Interventions

Pregnant smokers were randomized to vitamin C (500 mg/d) or placebo treatment.

Main Outcomes and Measures

The primary outcome was the prespecified measurement of FEF between 25% and 75% expired volume (FEF25-75) by spirometry at age 5 years. Secondary outcomes included FEF measurements at 50% and 75% of expiration (FEF50 and FEF75), forced expiratory volume in 1 second (FEV1), and occurrence of wheeze.

Results

Of the 251 pregnant smokers included in this study, 125 (49.8%) were randomized to vitamin C and 126 (50.2%) were randomized to placebo. Of 213 children from the VCSIP trial who were reconsented into this follow-up study, 192 (90.1%) had successful FEF measurements at age 5 years; 212 (99.5%) were included in the analysis of wheeze. Analysis of covariance demonstrated that offspring of pregnant smokers allocated to vitamin C compared with placebo had 17.2% significantly higher mean (SE) measurements of FEF25-75 at age 5 years (1.45 [0.04] vs 1.24 [0.04] L/s; adjusted mean difference, 0.21 [95% CI, 0.13-0.30]; P < .001). Mean (SE) measurements were also significantly increased by 14.1% for FEF50 (1.59 [0.04] vs 1.39 [0.04] L/s; adjusted mean difference, 0.20 [95% CI, 0.11-0.30]; P < .001), 25.9% for FEF75 (0.79 [0.02] vs 0.63 [0.02] L/s; 0.16 [95% CI, 0.11-0.22]; P < .001), and 4.4% for FEV1 (1.13 [0.02] vs 1.09 [0.02] L; 0.05 [95% CI, 0.01-0.09]; P = .02). In addition, offspring of pregnant smokers randomized to vitamin C had significantly decreased wheeze (28.3% vs 47.2%; estimated odds ratio, 0.41 [95% CI, 0.23-0.74]; P = .003).

Conclusions and Relevance

In this follow-up study of offspring of pregnant smokers randomized to vitamin C vs placebo, vitamin C supplementation during pregnancy resulted in significantly increased airway function of offspring at age 5 years and significantly decreased the occurrence of wheeze. These findings suggest that vitamin C supplementation for pregnant smokers may decrease the effects of smoking in pregnancy on childhood airway function and respiratory health.

Trial Registration

ClinicalTrials.gov Identifier: NCT03203603.

Changes in light absorption and composition of chromophoric marine-dissolved organic matter across a microbial bloom

Marine chromophoric dissolved organic matter (m-CDOM) mediates many vital photochemical processes at the ocean's surface. Isolating m-CDOM within the chemical complexity of marine dissolved organic matter has remained an analytical challenge. The SeaSCAPE campaign, a large-scale mesocosm experiment, provided a unique opportunity to probe the in situ production of m-CDOM across phytoplankton and microbial blooms. Results from mass spectrometry coupled with UV-VIS spectroscopy reveal production of a chemodiverse set of compounds well-correlated with increases in absorbance after a bacterial bloom, indicative of autochthonous m-CDOM production. Notably, many of the absorbing compounds were found to be enriched in nitrogen, which may be essential to chromophore function. From these results, quinoids, porphyrins, flavones, and amide-like compounds were identified via structural analysis and may serve as important photosensitizers in the marine boundary layer. Overall, this study demonstrates a step forward in identifying and characterizing m-CDOM using temporal mesocosm data and integrated UV-VIS spectroscopy and mass spectrometry analyses.

Vitamin C to Pregnant Smokers Persistently Improves Infant Airway Function to 12 Months of Age: A Randomised Trial

BACKGROUND

Vitamin C (500 mg·day-1) supplementation for pregnant smokers has been reported to increase newborn pulmonary function and infant forced expiratory flows (FEFs) at 3 months of age. Its effect on airway function through 12 months of age has not been reported.

OBJECTIVE

To assess whether vitamin C supplementation to pregnant smokers is associated with a sustained increased airway function in their infants through 12 months of age.

METHODS

This is a prespecified secondary outcome of a randomised, double-blind, placebo-controlled trial that randomised 251 pregnant smokers between 13 and 23 weeks of gestation: 125 to 500 mg·day-1 vitamin C and 126 to placebo. Smoking cessation counselling was provided. FEFs performed at 3 and 12 months of age were analysed by repeated measures analysis of covariance.

RESULTS

FEFs were performed in 222 infants at 3 months and 202 infants at 12 months of age. The infants allocated to vitamin C had significantly increased FEFs over the first year of life compared to those allocated to placebo. The overall increased flows were: 40.2 mL·sec-1 for FEF75 (adjusted 95% CI for difference 6.6 to 73.8; p=0.025); 58.3 mL·sec-1 for FEF50 (95% CI 10.9 to 105.8; p=0.0081); and 55.1 mL·sec-1 for FEF25-75 (95% CI, 9.7 to 100.5; p=0.013).

CONCLUSIONS

In offspring of pregnant smokers randomised to vitamin C versus placebo, vitamin C during pregnancy was associated with a small but significantly increased airway function at 3 and 12 months of age, suggesting a potential shift to a higher airway function trajectory curve. Continued follow-up is underway.

Improving Smoking Cessation Outcomes Through Tailored-Risk Patient Messages at a University Hospital Tobacco Cessation Service

BACKGROUND

Postdischarge follow-up is a critical step for increasing effectiveness of hospital smoking cessation treatment. A quality improvement project was undertaken at an academic medical center tobacco cessation consult service to evaluate whether a tailored message (TM) linking immediate risks of continued smoking-particularly carbon monoxide exposure-to hospital recovery would stimulate more patient interest in the hospital's cessation treatment, including agreement to postdischarge follow-up, compared to patients receiving the usual treatment protocol with a standard message (SM) regarding more general health benefits of abstinence.

METHODS

Data from 697 smokers ordered/referred for smoking cessation treatment in 2013 who received either the SM (January-April; n = 323) or the TM (April-November; n =374) were analyzed.

RESULTS

Multivariate regression analysis showed that the TM was associated with significantly greater agreement for follow-up (odds ratio [OR] = 10.83, 95% confidence interval [CI] = 3.66-32.04, p < 0.0001) than the SM. Those patients who received the TM were more willing to try to remain abstinent postdischarge (willingness score = 10, p = 0.0052) and engaged in longer consults (consult time > 10 minutes, p = 0.0075) than SM patients. TM patients also self-reported a higher continuous abstinence rate (OR = 2.07, 95% CI = 1.17-3.66, p = 0.0130] at follow-up than SM.

CONCLUSION

Linking risks of continued smoking, particularly carbon monoxide exposure, to hospital patients' immediate recovery following discharge in a treatment protocol resulted in longer consult times and increased agreement to follow-up compared to the usual protocol message. The TM was integrated into the hospital tobacco cessation intervention as standard of care.

Oral Vitamin C (500 mg/d) to Pregnant Smokers Improves Infant Airway Function at 3 Months (VCSIP). A Randomized Trial

Rationale: We reported a randomized trial demonstrating daily supplemental vitamin C to pregnant smokers significantly improved newborn pulmonary function tests. The current study tests these results in a new cohort using infant pulmonary function tests. Objectives: To determine if infants of pregnant smokers randomized to daily supplemental vitamin C would have improved forced expiratory flows (FEFs) at 3 months of age compared with those randomized to placebo, and to investigate the association of the α5 nicotinic acetylcholine receptor. Methods: A randomized, double-blind, placebo-controlled trial was conducted at three centers. Two hundred fifty-one pregnant smokers were randomized at 13-23 weeks of gestation: 125 randomized to vitamin C (500 mg/d) and 126 to placebo. Measurements and Main Results: The primary outcome was FEF75 at 3 months of age performed with the raised volume rapid thoracic compression technique (Jaeger/Viasys). FEF50 and FEF25-75 obtained from the same expiratory curves were prespecified secondary outcomes. The infants of pregnant smokers randomized to vitamin C (n = 113) had the following FEFs at 3 months of age compared with those randomized to placebo (n =  109) as measured by FEF75 (200.7 vs. 188.7 ml/s; adjusted 95% confidence interval [CI] for difference, -3.33 to 35.64; P = 0.10), FEF50 (436.7 vs. 408.5 ml/s; adjusted 95% CI for difference, 6.10-61.30; P = 0.02), and FEF25-75 (387.4 vs. 365.8 ml/s; adjusted 95% CI for difference, 0.92-55.34; P = 0.04). Infant FEFs seemed to be negatively associated with the maternal risk alleles for the α5 nicotinic acetylcholine receptor (rs16969968). Conclusions: Although the primary outcome of FEF75 was not improved after vitamin C supplementation to pregnant smokers, the predetermined secondary outcomes FEF50 and FEF25-75 were significantly improved. These results extend our previous findings and demonstrate improved airway function (FEF50 and FEF25-75) at 3 months of age in infants after vitamin C supplementation to pregnant smokers. Clinical trial registered with www.clinicaltrials.gov (NCT01723696).

Vitamin C supplementation for pregnant smoking women and pulmonary function in their newborn infants: a randomized clinical trial

IMPORTANCE

Maternal smoking during pregnancy adversely affects offspring lung development, with lifelong decreases in pulmonary function and increased asthma risk. In a primate model, vitamin C blocked some of the in-utero effects of nicotine on lung development and offspring pulmonary function.

OBJECTIVE

To determine if newborns of pregnant smokers randomized to receive daily vitamin C would have improved results of pulmonary function tests (PFTs) and decreased wheezing compared with those randomized to placebo.

DESIGN, SETTING, AND PARTICIPANTS

Randomized, double-blind trial conducted in 3 sites in the Pacific Northwest between March 2007 and January 2011. One hundred fifty-nine newborns of randomized pregnant smokers (76 vitamin C treated and 83 placebo treated) and 76 newborns of pregnant nonsmokers were studied with newborn PFTs. Follow-up assessment including wheezing was assessed through age 1 year, and PFTs were performed at age 1 year.

INTERVENTIONS

Pregnant women were randomized to receive vitamin C (500 mg/d) (n = 89) or placebo (n = 90).

MAIN OUTCOMES AND MEASURES

The primary outcome was measurement of newborn pulmonary function (ratio of the time to peak tidal expiratory flow to expiratory time [TPTEF:TE] and passive respiratory compliance per kilogram [Crs/kg]) within 72 hours of age. Secondary outcomes included incidence of wheezing through age 1 year and PFT results at age 1 year. A subgroup of pregnant smokers and nonsmokers had genotyping performed.

RESULTS

Newborns of women randomized to vitamin C (n = 76), compared with those randomized to placebo (n = 83), had improved pulmonary function as measured by TPTEF:TE (0.383 vs 0.345 [adjusted 95% CI for difference, 0.011-0.062]; P = .006) and Crs/kg (1.32 vs 1.20 mL/cm H2O/kg [95% CI, 0.02-0.20]; P = .01). Offspring of women randomized to vitamin C had significantly decreased wheezing through age 1 year (15/70 [21%] vs 31/77 [40%]; relative risk, 0.56 [95% CI, 0.33-0.95]; P = .03). There were no significant differences in the 1-year PFT results between the vitamin C and placebo groups. The effect of maternal smoking on newborn lung function was associated with maternal genotype for the α5 nicotinic receptor (rs16969968) (P < .001 for interaction).

CONCLUSIONS AND RELEVANCE

Supplemental vitamin C taken by pregnant smokers improved newborn PFT results and decreased wheezing through 1 year in the offspring. Vitamin C in pregnant smokers may be an inexpensive and simple approach to decrease the effects of smoking in pregnancy on newborn pulmonary function and respiratory morbidities.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00632476.

A resident-led institutional patient safety and quality improvement process

The authors used a multipronged approach to gain resident involvement in institutional quality improvement over a 3-year period; the initiative included a survey, a retreat, workgroups, a resurvey, and another retreat. Survey results (from 2007 compared with those of 2010) demonstrated significant improvement in almost all the top issues concerning patient safety for residents-emergency department boarding and crowding, adequacy of patient flow through the institution, adequacy of nursing and technical support staffing, and laboratory specimen handling (initial overall mean concern level was 2.87, and final concern level was 2.19; P < .01). This perceived improvement in patient safety concerns for residents was associated with observable improvements in areas of high concern for hospital leaders. By surveying residents and students, prioritizing concerns, convening a hospital-wide retreat with key leaders, and implementing accountable plans, the authors have demonstrated that resident perceptions of quality and safety can help drive quality improvement and engage residents in improvement efforts at an institutional level.

Immunogenicity and smoking-cessation outcomes for a novel nicotine immunotherapeutic

NicVAX^®, a nicotine vaccine (3’AmNic-rEPA), has been clinically evaluated to determine if higher antibody concentrations are associated with higher smoking abstinence rates and if doses and frequency of administration are associated with increased antibody response. This randomized, double-blinded, placebo-controlled multicenter clinical trial (N=301 smokers) tested 200 and 400 µg doses administered 4 or 5 times over 6 months compared to placebo. 3’AmNic-rEPA recipients with the highest serum anti-nicotine antibody response (top 30% by AUC) were significantly more likely to attain 8 weeks continuous abstinence from weeks 19 through 26 than the placebo recipients (24.6% vs. 12.0%, p=0.024, OR=2.69, 95% CI, 1.14–6.37). The 5 injection 400 µg dose regimen had the greatest antibody response and had significantly higher abstinence rates than placebo. This study demonstrates proof-of-concept that 3’AmNic-rEPA elicits antibodies to nicotine and is associated with higher continuous abstinence rates, justifying its further development as a treatment for nicotine dependence.

Immediate versus delayed quitting and rates of relapse among smokers treated successfully with varenicline, bupropion SR or placebo

AIMS

We assessed to what degree smokers who fail to quit on the target quit date (TQD) or lapse following TQD eventually achieve success with continued treatment.

DESIGN

A secondary analysis of pooled data of successful quitters treated with varenicline (306 of 696), bupropion (199 of 671) and placebo (121 of 685) from two identically-designed clinical trials of varenicline versus bupropion sustained-release and placebo.

SETTING

Multiple research centers in the US.

PARTICIPANTS

Adult smokers (n==2052) randomized to 12 weeks drug treatment plus 40 weeks follow-up.

MEASUREMENT

The primary end-point for the trials was continuous abstinence for weeks 9-12. TQD was day 8. Two patterns of successful quitting were identified. Immediate quitters (IQs) were continuously abstinent for weeks 2-12. Delayed quitters (DQs) smoked during 1 or more weeks for weeks 2-8.

FINDINGS

Cumulative continuous abstinence (IQs + DQs) increased for all treatments during weeks 3-8. Overall IQs and DQs for varenicline were (24%; 20%) versus bupropion (18.0%, P=0.007; 11.6%, P<0.001) or placebo (10.2%, P<0.001; 7.5%, P<0.001). However, DQs as a proportion of successful quitters was similar for all treatments (varenicline 45%; bupropion 39%; placebo 42%) and accounted for approximately one-third of those remaining continuously abstinent for weeks 9-52. No gender differences were observed by quit pattern. Post-treatment relapse was similar across groups.

CONCLUSIONS

Our data support continuing cessation treatments without interruption for smokers motivated to remain in the quitting process despite lack of success early in the treatment.

Code Status Discussions at Hospital Admission Are Not Associated With Patient and Surrogate Satisfaction With Hospital Care: Results From the Multicenter Hospitalist Study

Background: Physicians may avoid code status discussions for fear of decreasing patient or surrogate satisfaction. Methods: Charts of patients admitted to medical services at 6 university hospitals were reviewed for documentation of a code status discussion in the first 24 hours of admission. Satisfaction with care provided during the hospitalization was assessed by telephone 1 month after discharge. Results: Of the 11 717 patients with 1-month follow-up, 1090 (9.3%) had a code status discussion documented. Patient or surrogate satisfaction did not differ by whether a discussion was documented. The lack of association persisted after adjusting for patient’s severity of illness and using propensity adjustment for likelihood of having a discussion. Conclusions: Discussing code status on admission to the inpatient setting did not affect patient or surrogate satisfaction.

A randomized controlled trial of adding the nicotine patch to rimonabant for smoking cessation: efficacy, safety and weight gain

AIMS

Because smoking cessation rates might be improved by combining drugs and by reducing post-cessation weight gain, we tested the smoking cessation efficacy, safety and effect on body weight of adding the nicotine patch to rimonabant, a cannabanoid type-1 receptor antagonist that reduces body weight.

DESIGN

Randomized double-blind placebo-controlled trial.

SETTING

Fifteen US research centers.

PARTICIPANTS

A total of 755 smokers (> OR = 15 cigarettes/day). Intervention Rimonabant (20 mg daily) was given open-label for 9 weeks. The 735 participants completing week 1 were randomized at day 8 (target quit day) to add a nicotine patch (n = 369) or placebo patch (n = 366) for 10 weeks (21 mg daily for 8 weeks plus a 2-week taper). Participants received weekly smoking counseling and were followed for 24 weeks.

MEASUREMENTS

Biochemically validated 4-week continuous abstinence at end-of-treatment (weeks 6-9; primary end-point); 7-day point prevalence abstinence at weeks 9 and 24; sustained abstinence (weeks 6-24); change in body weight; and adverse events.

FINDINGS

Rimonabant plus nicotine patch was superior to rimonabant plus placebo in validated continuous abstinence at weeks 6-9 (39.0% versus 21.3%; odds ratio 2.36, 95% confidence interval: 1.71-2.37; P < 0.01) and in all other efficacy measures. Mean end-of-treatment weight gain among quitters did not differ between groups (0.04 kg for combination versus 0.49 kg for rimonabant only, P = 0.15) and was similar in weight-concerned smokers. Serious adverse event rates did not differ between groups. Depression- and anxiety-related adverse events occurred in 32 (4.2%) and 44 (5.8%) subjects, respectively; eight (1.1%) and nine (1.2%) subjects stopped the drug due to depression and anxiety, respectively.

CONCLUSIONS

Adding a nicotine patch to rimonabant was well tolerated and increased smoking cessation rates over rimonabant alone. There was little post-cessation weight gain in either group, even among weight-concerned smokers, during drug treatment.

Factors associated with discussion of care plans and code status at the time of hospital admission: results from the Multicenter Hospitalist Study

BACKGROUND

Hospital admission is a time when patients are sickest and also often encountering an entirely new set of caregivers. As a result, understanding and documenting a patient's care preferences at hospital admission is critically important.

OBJECTIVE

To understand factors associated with documentation of care planning discussions in patients admitted to general medical services at 6 academic medical centers.

DESIGN

Observational cohort study using data collected during the Multicenter Hospitalist Study, conducted between July 1, 2002 and June 30, 2004.

SETTING

Prospective trial enrolling patients admitted to general medicine services at 6 university-based teaching hospitals.

PATIENTS

Patients were eligible for this study if they were 18 years of age or older, admitted to a hospitalist or nonhospitalist physician, and able to give informed consent.

MEASUREMENTS

Presence of chart documentation that the admitting team had discussed care plans with the patient within the first 24 hours of hospitalization. Notations such as "full code" were not counted as a discussion, whereas notations such as "discussed care wishes and plan with patient" were counted.

RESULTS

A total of 17,097 patients over the age of 18 gave informed consent and completed an interview and chart abstraction; of these, 1776 (10.3%) had a code status discussion (CD) documented in the first 24 hours of their admission. Patients with a CD were older (69 years vs. 56 years, P < 0.0001), more often white (52.8% vs. 43.3%, P < 0.0001), and more likely to have cancer (19.8% vs. 11.4%, P < 0.0001), or depression (35.1% vs. 30.9%, P < 0.0001). There was marked variability in CD documentation across sites of enrollment (2.8%-24.9%, P < 0.0001). Despite strong associations seen in unadjusted comparisons, in multivariable models many socioeconomic factors, functional status, comorbid illness, and documentation of a surrogate decision maker were only moderately associated with a CD (adjusted odds ratios all less than 2.0). However, patients' site of enrollment (odds ratios 1.74-5.14) and informal notations describing prehospital care wishes (eg, orders for "do not resuscitate"/"do not intubate;" odds ratios 3.22-11.32 compared with no preexisting documentation) were powerfully associated with CD documentation. Site remained a powerful influence even in patients with no documented prehospital wishes.

LIMITATIONS

Our results are derived from a relatively small number of academic sites, and we cannot connect documentation differences to differences in patient outcomes.

CONCLUSIONS

Documentation of a CD at admission was more strongly associated with informal documentation of prehospital care wishes and where the patient was hospitalized than legal care planning documents (such as durable power of attorney), or comorbid illnesses. Efforts to improve communication between hospitalists and their patients might target local documentation practices and culture.

Quality of care for decompensated heart failure: comparable performance between academic hospitalists and non-hospitalists

BACKGROUND

Hospitalists improve efficiency, but little information exists regarding whether they impact quality of care.

OBJECTIVE

To determine hospitalists' effect on the quality of acute congestive heart failure care.

DESIGN AND PARTICIPANTS

Using data from the Multicenter Hospitalist Study, we retrospectively evaluated quality of care in patients admitted with congestive heart failure who were assigned to hospitalists (n = 120) or non-hospitalists (n = 252) among six academic hospitals.

MEASUREMENTS

Quality measures included the percentage of patients who had ejection fraction (EF) measurement, received appropriate medications [i.e., angiotensin-converting enzyme inhibitor (ACE-I) or beta-blockers] at discharge, measures of care coordination (e.g., follow-up within 30 days), testing for cardiac ischemia (e.g., cardiac catheterization), as well as hospital length of stay, cost, and combined 30-day readmissions and mortality.

RESULTS

Compared to non-hospitalist physicians, hospitalists' patients had similar rates of EF measurement (85.3% vs. 87.5%; P = 0.57), ACE-I (91.5% vs. 88.0%; P = 0.52), or beta-blocker (46.9% vs. 42.1%; P = 0.57) prescriptions. Multivariable adjustment did not change these findings. Hospitalists' patients had higher odds of 30-day follow-up (adjusted OR = 1.83, 95% CI, 1.44 - 2.93). There were no significant differences between the groups' frequency of cardiac testing, length of stay, costs, or risk for readmission or death by 30-days.

CONCLUSION

Academic hospitalists and non-hospitalists provide similar quality of care for heart failure patients, although hospitalists are paying more attention to longitudinal care. Future efforts to improve quality of care in decompensated heart failure may require attention towards system-level factors.

Do hospitalists or physicians with greater inpatient HIV experience improve HIV care in the era of highly active antiretroviral therapy? Results from a multicenter trial of academic hospitalists

BACKGROUND

Little is known about the effect of provider type and experience on outcomes, resource use, and processes of care of hospitalized patients with human immunodeficiency virus (HIV) infection. Hospitalists are caring for this population with increasing frequency.

METHODS

Data from a natural experiment in which patients were assigned to physicians on the basis of call cycle was used to study the effects of provider type-that is, hospitalist versus nonhospitalist-and HIV-specific inpatient experience on resource use, outcomes, and selected measures of processes of care at 6 academic institutions. Administrative data, inpatient interviews, 30-day follow-up interviews, and the National Death Index were used to measure outcomes.

RESULTS

A total of 1207 patients were included in the analysis. There were few differences in resource use, outcomes, and processes of care by provider type and experience with HIV-infected inpatients. Patients who received hospitalist care demonstrated a trend toward increased length of hospital stay compared with patients who did not receive hospitalist care (6.0 days vs. 5.2 days; P = .13). Inpatient providers with moderate experience with HIV-infected patients were more likely to coordinate care with outpatient providers (odds ratio, 2.40; P = .05) than were those with the least experience with HIV-infected patients, but this pattern did not extend to providers with the highest level of experience.

CONCLUSION

Provider type and attending physician experience with HIV-infected inpatients had minimal effect on the quality of care of HIV-infected inpatients. Approaches other than provider experience, such as the use of multidisciplinary inpatient teams, may be better targets for future studies of the outcomes, processes of care, and resource use of HIV-infected inpatients.

Exercise-induced promotion of hippocampal cell proliferation requires beta-endorphin

Adult hippocampal neurogenesis is influenced by a variety of stimuli, including exercise, but the mechanisms by which running affects neurogenesis are not yet fully understood. Because beta-endorphin, which is released in response to exercise, increases cell proliferation in vitro, we hypothesized that it could exert a similar effect in vivo and mediate the stimulatory effects of running on neurogenesis. We thus analyzed the effects of voluntary wheel-running on adult neurogenesis (proliferation, differentiation, survival/death) in wild-type and beta-endorphin-deficient mice. In wild-type mice, exercise promoted cell proliferation evaluated by sacrificing animals 24 h after the last 5-bromo-2'-deoxyuridine (BrdU) pulse and by using endogenous cell cycle markers (Ki67 and pH(3)). This was accompanied by an increased survival of 4-wk-old BrdU-labeled cells, leading to a net increase of neurogenesis. Beta-endorphin deficiency had no effect in sedentary mice, but it completely blocked the running-induced increase in cell proliferation; this blockade was accompanied by an increased survival of 4-wk-old cells and a decreased cell death. Altogether, adult neurogenesis was increased in response to exercise in knockout mice. We conclude that beta-endorphin released during running is a key factor for exercise-induced cell proliferation and that a homeostatic balance may regulate the final number of new neurons.

Support for spirituality in smoking cessation: results of pilot survey

Patient spiritual resources are increasingly included in the treatment of medical conditions such as cancers and alcohol and drug dependence, but use of spiritual resources is usually excluded from tobacco dependence treatment. We hypothesized that this omission may be linked to perceived resistance from smokers. To examine this hypothesis, we conducted a pilot survey to assess whether current smokers would consider spiritual, including religious, resources helpful if they were planning to quit. Smokers at least 18 years of age at Oregon Health & Science University in Portland, Oregon, (N=104) completed a brief survey of smoking behaviors and spiritual beliefs. None were attempting to quit. Of these individuals, 92 (88%) reported some history of spiritual resources (spiritual practice or belief in a Higher Power), and of those respondents, 78% reported that using spiritual resources to quit could be helpful, and 77% reported being open to having their providers encourage use of spiritual resources when quitting. Results of logistic regression analysis indicated that those aged 31-50 years (OR=3.3), those over age 50 years (OR=5.4), and women (OR=3.4) were significantly more likely to have used spiritual resources in the past. Of the 92 smokers with any history of spiritual resources, those smoking more than 15 cigarettes/day were significantly more receptive to provider encouragement of spiritual resources in a quit attempt (OR=5.4). Our data are consistent with overall beliefs in the United States about spirituality and recent trends to include spirituality in health care. We conclude that smokers, especially heavier smokers, may be receptive to using spiritual resources in a quit attempt and that spirituality in tobacco dependence treatment warrants additional investigation and program development.

Efficacy and Safety of the Novel Selective Nicotinic Acetylcholine Receptor Partial Agonist, Varenicline, for Smoking Cessation

BACKGROUND

The selective nicotinic acetylcholine receptor partial agonist, varenicline tartrate, represents a novel type of therapy for smoking cessation. This study evaluated the efficacy, safety, and tolerability of 4 varenicline dose regimens, 2 with progressive dosing over the first week (eg, titrated) and 2 with a fixed dosing schedule (eg, non-titrated), for promoting smoking cessation.

METHODS

This multicenter, double-blind, placebo-controlled study randomized healthy smokers (aged 18-65 years) to varenicline tartrate, 0.5 mg twice daily nontitrated (n = 129), 0.5 mg twice daily titrated (n = 130), 1.0 mg twice daily nontitrated (n = 129), 1.0 mg twice daily titrated (n = 130), or placebo (n = 129) for 12 weeks to aid in smoking cessation. A 40-week follow-up period assessed long-term efficacy. The primary efficacy measures were the carbon monoxide-confirmed 4-week continuous quit rates by pooled dosage group for weeks 4 through 7 and 9 through 12 and the continuous abstinence rates for weeks 9 through 52.

RESULTS

Weeks 9 through 12 continuous quit rates were greater in the 1.0-mg group (49.4%) and the 0.5-mg group (44.0%) vs placebo (11.6%; P<.001 vs both doses). Weeks 9 through 52 abstinence rates were greater in the 1.0-mg group (22.4%; P<.001) and the 0.5-mg group (18.5%; P<.001) vs placebo (3.9%). Varenicline was generally well tolerated, with nausea occurring in 16% to 42% of varenicline-treated subjects. Reports of nausea were lower for the titrated vs nontitrated dosing and infrequently led to medication discontinuation.

CONCLUSION

Varenicline tartrate, 0.5 mg and 1.0 mg twice daily, is efficacious for smoking cessation.

Smoking Cessation With Varenicline, a Selective α4β2 Nicotinic Receptor Partial Agonist

BACKGROUND

Currently available smoking cessation therapies have limited success rates. Varenicline tartrate is a novel, selective nicotinic receptor partial agonist developed specifically for smoking cessation. This study evaluated the efficacy, tolerability, and safety of 3 varenicline doses for smoking cessation. Bupropion hydrochloride was included as an active control.

METHODS

A phase 2, multicenter, randomized, double-blind, placebo-controlled study of healthy smokers (18-65 years old). Subjects were randomized to varenicline tartrate, 0.3 mg once daily (n = 128), 1.0 mg once daily (n = 128), or 1.0 mg twice daily (n = 127), for 6 weeks plus placebo for 1 week; to 150-mg sustained-release bupropion hydrochloride twice daily (n = 128) for 7 weeks; or to placebo (n = 127) for 7 weeks.

RESULTS

During the treatment phase, the continuous quit rates for any 4 weeks were significantly higher for varenicline tartrate, 1.0 mg twice daily (48.0%; P<.001) and 1.0 mg once daily (37.3%; P<.001), than for placebo (17.1%). The bupropion rate was 33.3% (P = .002 vs placebo). The carbon monoxide-confirmed continuous quit rates from week 4 to week 52 were significantly higher in the varenicline tartrate, 1.0 mg twice daily, group compared with the placebo group (14.4% vs 4.9%; P = .002). The bupropion rate was 6.3% (P = .60 vs placebo). Discontinuation owing to treatment-emergent adverse events was 15.9% for bupropion, 11.2% to 14.3% for varenicline, and 9.8% for placebo. No dose-related increases occurred in adverse events for varenicline.

CONCLUSIONS

Varenicline tartrate demonstrated both short-term (1 mg twice daily and 1 mg once daily) and long-term efficacy (1 mg twice daily) vs placebo. Varenicline was well tolerated and may provide a novel therapy to aid smoking cessation.

Varenicline, an alpha4beta2 nicotinic acetylcholine receptor partial agonist, vs sustained-release bupropion and placebo for smoking cessation: a randomized controlled trial

CONTEXT

The alpha4beta2 nicotinic acetylcholine receptors (nAChRs) are linked to the reinforcing effects of nicotine and maintaining smoking behavior. Varenicline, a novel alpha4beta2 nAChR partial agonist, may be beneficial for smoking cessation.

OBJECTIVE

To assess efficacy and safety of varenicline for smoking cessation compared with sustained-release bupropion (bupropion SR) and placebo.

DESIGN, SETTING, AND PARTICIPANTS

Randomized, double-blind, parallel-group, placebo- and active-treatment-controlled, phase 3 clinical trial conducted at 19 US centers from June 19, 2003, to April 22, 2005. Participants were 1025 generally healthy smokers (> or =10 cigarettes/d) with fewer than 3 months of smoking abstinence in the past year, 18 to 75 years old, recruited via advertising.

INTERVENTION

Participants were randomly assigned in a 1:1:1 ratio to receive brief counseling and varenicline titrated to 1 mg twice per day (n = 352), bupropion SR titrated to 150 mg twice per day (n = 329), or placebo (n = 344) orally for 12 weeks, with 40 weeks of nondrug follow-up.

MAIN OUTCOME MEASURES

Primary outcome was the exhaled carbon monoxide-confirmed 4-week rate of continuous abstinence from smoking for weeks 9 through 12. A secondary outcome was the continuous abstinence rate for weeks 9 through 24 and weeks 9 through 52.

RESULTS

For weeks 9 through 12, the 4-week continuous abstinence rates were 44.0% for varenicline vs 17.7% for placebo (odds ratio [OR], 3.85; 95% confidence interval [CI], 2.70-5.50; P<.001) and vs 29.5% for bupropion SR (OR, 1.93; 95% CI, 1.40-2.68; P<.001). Bupropion SR was also significantly more efficacious than placebo (OR, 2.00; 95% CI, 1.38-2.89; P<.001). For weeks 9 through 52, the continuous abstinence rates were 21.9% for varenicline vs 8.4% for placebo (OR, 3.09; 95% CI, 1.95-4.91; P<.001) and vs 16.1% for bupropion SR (OR, 1.46; 95% CI, 0.99-2.17; P = .057). Varenicline reduced craving and withdrawal and, for those who smoked while receiving study drug, smoking satisfaction. No sex differences in efficacy for varenicline were observed. Varenicline was safe and generally well tolerated, with study drug discontinuation rates similar to those for placebo. The most common adverse events for participants receiving active-drug treatment were nausea (98 participants receiving varenicline [28.1%]) and insomnia (72 receiving bupropion SR [21.9%]).

CONCLUSION

Varenicline was significantly more efficacious than placebo for smoking cessation at all time points and significantly more efficacious than bupropion SR at the end of 12 weeks of drug treatment and at 24 weeks.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00141206.

Bupropion SR for relapse prevention: a "slips-allowed" analysis

OBJECTIVE

To assess the efficacy of bupropion SR on smoking abstinence using a "slips allowed" analysis.

METHODS

Retrospective analysis, which did not consider brief episodic "slips" as a return to regular smoking, of data from a multicenter, randomized, doubleblind, placebo-controlled relapse prevention study.

RESULTS

Using a slips-allowed analysis, median time to relapse on bupropion SR was 65 weeks versus 30 weeks on placebo. This is compared to 32 and 20 weeks, respectively, using a traditional analysis not allowing for slips.

CONCLUSION

Bupropion SR is efficacious for the prevention of smoking relapse. A slips-allowed analysis may provide a more clinically relevant assessment of efficacy.

Developing a successful hospitalist program

In 1998, St. Vincent's Hospital in Santa Fe, New Mexico, became one of the first hospitals to develop a hospitalist program. The administration and physicians discovered critical elements that must be built to achieve success.

Bupropion for pharmacologic relapse prevention to smoking: predictors of outcome

The aim of this study was to identify predictors of successful relapse prevention in smokers receiving long-term sustained-release bupropion. Smokers (N= 784) who were interested in stopping smoking were enrolled in a 7-week, open-label bupropion phase. Abstinent subjects at the end of treatment and eligible to proceed (N= 429) were randomized to active bupropion or placebo through Week 52 and then followed for an additional year. The best overall predictor of less relapse to smoking was assignment to active bupropion. In aggregate, the results indicate that bupropion can be prescribed to diverse populations of smokers with expected comparable results. There was a medication effect that was independent of any predictor except older age and those who gained no or minimal weight during the open-label phase. Predictors of successful relapse prevention included lower baseline smoking rates, a Fagerström Tolerance Questionnaire score of < 6, and initiation of smoking at an older age. These data should encourage others to perform similar pharmacologic relapse prevention studies with this or other pharmacotherapies.

Effects of gender on relapse prevention in smokers treated with bupropion SR

BACKGROUND

Recent data suggest that women smokers respond differently than men to cessation pharmacotherapies, particularly nicotine replacement therapy (NRT). Lower abstinence and higher relapse rates are often reported for women treated with NRT. Gender effects for those treated with non-nicotinic, bupropion-hydrochloride sustained release for relapse prevention have not been studied.

METHODS

Data from a multicenter relapse-prevention (RP) trial of bupropion (November 1995-June 1998) were analyzed for gender differences. Men and women smokers (N=784) were treated with open-label bupropion for 7 weeks. Those abstinent at Week 7 (n=432) were enrolled in the double-blind relapse-prevention phase and randomized to placebo or continued bupropion for 45 additional weeks.

RESULTS

Differences in point-prevalence abstinence rates between men (61.8%) and women (55.6%) in open-label bupropion (Week 7) were not significant. In the RP-phase Week 52, continuous abstinence rates for men and women were 37.8% and 36.4% (bupropion) and 36.6% and 29.9% (placebo), respectively; point-prevalence abstinence rates for men and women were 54.1% and 55.9% (bupropion) and 42.9% and 41.3% (placebo), respectively. Abstinence rates and time to relapse were superior for both men and women who received longer treatment. Gender differences within treatment groups were not significant. Median time to relapse was equal for men and women within each treatment group: Week 32 for bupropion and Week 20 for placebo.

CONCLUSIONS

Our data suggest that bupropion is a promising pharmacotherapy for preventing relapse, particularly for women.

The effect of bupropion sustained-release on cigarette craving after smoking cessation

BACKGROUND

Most (>50%) smokers who attempt to stop smoking relapse within the first year of abstinence. The effect of continued use of pharmacotherapy for smoking cessation on relapse rates is unknown. Bupropion sustained-release (SR) is the first non-nicotine-based therapy that is effective for achieving abstinence from smoking.

OBJECTIVE

This analysis explored the factors involved in relapse to smoking in patients who had successfully stopped smoking using bupropion SR. These patients were participants in a double-blind, placebo-controlled trial of bupropion SR for the prevention of relapse to smoking.

METHODS

Participants who had stopped smoking with 7 weeks of open-label bupropion SR were randomly assigned to receive double-blind treatment with either bupropion SR or placebo for 45 weeks. The primary efficacy outcome of the main study was the rate of relapse to smoking. The analyses presented here examine the levels of reported cigarette craving and, in those participants who returned to smoking, the reasons associated with relapse, using patient-completed questionnaires.

RESULTS

Craving was cited most frequently as a factor contributing to relapse in those participants receiving placebo (cited by 49.2% of relapsers) but significantly less frequently by participants receiving bupropion SR (cited by 22.4% of relapsers) (P < 0.05). Results from patients' diaries showed no differences between bupropion SR and placebo in terms of "craving in the past 24 hours" but significantly lower scores for "craving right now" for bupropion SR at weeks 11 and 12 (P < 0.05). Results at scheduled visits showed that "craving in the past 24 hours" was significantly less with bupropion SR compared with placebo at weeks 12, 20, and 48, and "craving right now" was significantly less with bupropion SR compared with placebo at weeks 12, 16, 20, 24, 48, and 52 (P < 0.05).

CONCLUSIONS

Craving continues to be a significant concern for individuals even after they have successfully stopped smoking. Bupropion SR appears to reduce reported cravings, which may contribute to the overall reduction in the rate of relapse observed with this pharmacotherapy.

Sustained-release bupropion for pharmacologic relapse prevention after smoking cessation. a randomized, controlled trial

BACKGROUND

Smoking relapse is common after successful pharmacologic treatment for smoking cessation. No previous studies have examined long-term drug therapy used expressly for prevention of smoking relapse.

OBJECTIVE

To evaluate the efficacy of bupropion to prevent smoking relapse.

DESIGN

Randomized, placebo-controlled trial.

PARTICIPANTS

784 healthy community volunteers who were motivated to quit smoking and who smoked at least 15 cigarettes per day.

INTERVENTION

The participants received open-label, sustained-release bupropion, 300 mg/d, for 7 weeks. Participants who were abstinent throughout week 7 of open-label treatment were randomly assigned to receive bupropion, 300 mg/d, or placebo for 45 weeks and were subsequently followed for an additional year after the conclusion of the medication phase. Participants were briefly counseled at all follow-up visits. At the end of open-label bupropion treatment, 461 of 784 participants (58.8%) were abstinent from smoking.

MEASUREMENT

Self-reported abstinence was confirmed by an expired air carbon monoxide concentration of 10 parts per million or less.

RESULTS

The point prevalence of smoking abstinence was significantly higher in the bupropion group than in the placebo group at the end (week 52) of drug therapy (55.1% vs. 42.3%, respectively; P = 0.008) and at week 78 (47.7% vs. 37.7%; P = 0.034) but did not differ at the final (week 104) follow-up visit (41.6% vs. 40.0%). The median time to relapse was significantly greater for bupropion recipients than for placebo recipients (156 days vs. 65 days; P = 0.021). The continuous abstinence rate was higher in the bupropion group than in the placebo group at study week 24 (17 weeks after randomization) (52.3% vs. 42.3%; P = 0.037) but did not differ between groups after week 24. Weight gain was significantly less in the bupropion group than in the placebo group at study weeks 52 (3.8 kg vs. 5.6 kg; P = 0.002) and 104 (4.1 kg vs. 5.4 kg; P = 0.016).

CONCLUSIONS

In persons who stopped smoking with 7 weeks of bupropion treatment, sustained-release bupropion for 12 months delayed smoking relapse and resulted in less weight gain.

Smoking cessation in patients with chronic obstructive pulmonary disease: a double-blind, placebo-controlled, randomised trial

BACKGROUND

Tobacco smoking is associated with chronic obstructive pulmonary disease (COPD) in more than 80% of cases. Our aim was to investigate the effect of sustained-release bupropion (amfebutamone) (SR) in promoting abstinence from smoking in patients with COPD.

METHODS

In a double-blind, randomised, placebo-controlled trial 404 individuals with mild or moderate COPD who smoked 15 or more cigarettes per day, were assigned bupropion SR (150 mg twice daily) or placebo for 12 weeks. All patients received smoking cessation counselling. Study medication was taken for 1 week before patients attempted to stop smoking. The primary efficacy endpoint was the complete and continuous abstinence from smoking from the beginning of week 4 to the end of week 7. Participants were followed up at month 6. Analysis was by intention to treat.

FINDINGS

All patients were chronic smokers with a smoking history of about 51 pack-years. Continuous smoking abstinence rates from week 4 to 7 were significantly higher in participants receiving bupropion SR than in those receiving placebo (28% [57/204] vs 16% [32/200], p=0.003). Continuous abstinence rates from weeks 4 to 12 (18% [36/204] vs 10% [20/200]) and weeks 4 to 26 (16% [32/204] vs 9% [18/200]) were also higher in participants receiving bupropion SR than in those taking placebo (p<0.05). Furthermore, symptoms of tobacco craving and withdrawal were attenuated in those receiving bupropion SR. Seven individuals discontinued study medication because of adverse events.

INTERPRETATION

Bupropion SRis a well-tolerated and effective aid to smoking cessation in people with mild to moderate COPD.

Synchronous water-clear cell double parathyroid adenomas a hitherto uncharacterized entity?

Water-clear cell hyperplasia is a rare but well-documented cause of primary hyperparathyroidism. Parathyroid adenomas of the water-clear cell type are exceptionally rare, and only 2 cases have been reported. We describe a patient with synchronous water-clear cell double parathyroid adenomas, an entity that has not previously been reported. In our case, the enlarged superior parathyroid glands were completely replaced by water-clear cells, with only a minute rim of extracapsular, histologically unremarkable parathyroid tissue. The inferior parathyroid glands were grossly unremarkable, and incisional biopsy specimens were histologically normal (no foci of water-clear cells were identified). The findings in this case are most consistent with the diagnosis of double adenomas of the water-clear cell type. We acknowledge that despite molecular proof of monoclonality of the 2 lesions, it is not possible to entirely exclude the possibility that this unusual case could be due to asymmetric hyperplasia.

Instability studies of porcine somatotropin in aqueous solutions and the possible reagents for its stabilization

The instability of porcine somatotropin (pST) in various solutions and possible stabilization of the hormone by sugars and mild detergents were studied. Aggregation and decomposition of the hormone molecules in various pH solutions and under presence of sugar or detergent were monitored by gel permeation chromatography (GPC) or ultraviolet spectroscopy (UV). The pST is a very unstable hormone in an aqueous environment. It was found in this project that the peptide hormone underwent aggregation or decomposition quickly in acidic and alkaline solutions but slowly in neutral pH solutions. High losses of pST monomers were seen in concentrated solutions of the hormone. On the other hand, pST monomers were stabilized to a certain degree in glucose solutions and at a low concentration of urea. These results should facilitate the development of efficient controlled-release systems which are essential for commercializing porcine somatotropin.

Modular elements of the MLC 1f/3f locus confer fiber-specific transcription regulation in transgenic mice

The two proteins encoded by the fast alkali myosin light chain (MLC) 1f/3f locus are developmentally regulated, muscle specific, and expressed exclusively in fast-twitch fibers. Their expression is independently regulated by two separate promoters and a downstream enhancer. Previous studies showed a reporter gene directed by the rat MLC If promoter and MLC enhancer to exhibit correct skeletal muscle-specific expression in transgenic mice during development and to be preferentially expressed in fast-twitch Type IIB fibers [Donoghue et al., (1991) J. Cell B.ol. 115:423-434]. The MLC 3f promoter also directed muscle-specific expression of a CAT reporter gene in adult transgenic mice and showed little dependence upon the enhancer. Here, we show that the MLC 3f promoter also directs transgene expression in the fast-twitch fibers of adult skeletal muscle, but almost exclusively to fiber Types IIA and IIX. MLC 3f transgene expression occurs in only a subset of the fiber types that express the endogenous locus, indicating modular elements included in the transgene confer fiber-specific transcription regulation. MyoD protein was also found to be restricted to fiber Types IIA and IIX, providing evidence for its possible role in mediating fiber-specific gene expression.

Predictors of initial smoking cessation and relapse through the first 2 years of the Lung Health Study

Analyses were made separately for men and women of the predictors of end-of-treatment (4 months) smoking cessation and subsequent relapse at 12 and 24 months among 3,923 participants enrolled in the Lung Health Study's 12-week cognitive-behavioral group smoking cessation program. Nicotine gum (2 mg) was available to all participants. Men were more likely than women to quit smoking initially, but relapse rates were similar for both genders. Baseline variables associated with initial quitting for both genders included greater education, lower nicotine dependence, and fewer respiratory symptoms. The best predictor of relapse between 4 and 12 months was smoking at least 1 cigarette between quit day and 4 months. Nicotine gum use at 12 months predicted relapse by 24 months for both genders. Greater social and environmental support for quitting smoking were the only factors that predicted both initial quitting and relapse for both genders. Clinical implications are discussed.

Predictors of initial smoking cessation and relapse through the first 2 years of the Lung Health Study

Analyses were made separately for men and women of the predictors of end-of-treatment (4 months) smoking cessation and subsequent relapse at 12 and 24 months among 3,923 participants enrolled in the Lung Health Study's 12-week cognitive-behavioral group smoking cessation program. Nicotine gum (2 mg) was available to all participants. Men were more likely than women to quit smoking initially, but relapse rates were similar for both genders. Baseline variables associated with initial quitting for both genders included greater education, lower nicotine dependence, and fewer respiratory symptoms. The best predictor of relapse between 4 and 12 months was smoking at least 1 cigarette between quit day and 4 months. Nicotine gum use at 12 months predicted relapse by 24 months for both genders. Greater social and environmental support for quitting smoking were the only factors that predicted both initial quitting and relapse for both genders. Clinical implications are discussed.

A new endotracheal tube for carbon dioxide and KTP laser surgery of the aerodigestive tract

We have tested the fire-resistance of a new endotracheal tube designed for use in laser surgery of the upper aerodigestive tract. This Teflon/metallic-wrapped silicone tube seems capable of withstanding occasional, accidental pulsed laser impact at power settings used clinically (1 to 10 watts) without fire. On rare occasions when continuous mode is used, the tube seems capable of withstanding at least several seconds of continuous irradiation at clinical power settings without igniting. When used with other recommended safety procedures, this tube should minimize the risk of endotracheal tube fire from accidental laser impact.

A congenic line of the BALB/c mouse strain with the endogenous mouse mammary tumor virus proviral gene Mtv-3: tissue-specific expression and correlation with resistance to mouse mammary tumor virus infection and tumorigenesis

Mouse mammary tumor virus (MMTV) expression and MMTV-induced tumorigenesis were studied in a congenic line of the BALB/cHeA strain, termed BALB/c-Mtv-3+, that carries the Mtv-3 proviral gene. BALB/c-Mtv-3+ mice were free of milk-transmitted MMTV and did not spontaneously develop mammary tumors. A specific Mtv-3 expression was observed in the mammary gland and spleen, but not in other lymphoid tissues, such as thymus and bone marrow. This expression was hormone dependent, as shown by the increase of MMTV mRNA during pregnancy. At the protein level, large amounts of p28, but only traces of gp52, the main MMTV core and envelope antigens, respectively, were observed, in agreement with the already described "partial" expression of the Mtv-3 gene products. The presence of the 24S (3.8 kilobases) mRNA encoding the MMTV env antigens in the spleen and the low gp52 reactivity in lactating mammary glands showed that this noncoordinate expression was probably due to a defect in translation or posttranslational processing of env proteins. The susceptibility of BALB/c-Mtv-3+ to experimental MMTV infection was studied. The presence of Mtv-3 conferred to BALB/c mice resistance to MMTV infection, as shown by measuring viral antigens released in the milk of infected mice and by recording the incidence of early mammary tumors. The presence of a nontumorigenic endogenous MMTV gene was therefore protective against exogenous MMTV infection.

Effects of inhibitory and stimulatory photoperiods and sexual maturation on the ability of hamster testes to respond to hCG in vitro

The decrease in gonadal weight produced in adult golden hamsters by exposure to short photoperiods was accompanied by a marked reduction in the ability of the testes to produce testosterone from endogenous precursors in vitro, both without and with hCG stimulation. These changes were significant after 4-7 weeks in short photoperiod (5L: 19D) and were even more pronounced after 17-20 weeks. Production of testosterone in vitro by testes of immature hamsters was comparable to values obtained in adult animals with short photoperiod-induced gonadal atrophy. Delay of sexual maturation induced by daily injections of bromocriptine was accompanied by a further decrease in testicular testosterone production in vitro. Exposure of gonadally-regressed adult hamsters to a long, stimulatory photoperiod (14L: 10D) produced a rapid and marked increase in testicular testosterone production, which was coincident with the previously demonstrated increase in serum gonadotrophin levels after 1-5 days of photostimulation. Furthermore, testosterone production in vitro by regressed testes of animals exposed to short photoperiod was increased significantly by one large dose of hCG administered 26 h before killing the animals. It is concluded that the suppressive effects of short photoperiods on the ability of the hamster testis to produce testosterone and to respond to hCG stimulation are due to reductions in endogenous LH, FSH and prolactin release, with a consequent loss of testicular LH/hCG receptors and decreased activity of enzymes involved in the biosynthesis of testosterone.

Age-related change in parathyroid hormone-dependent cyclic AMP formation in rat kidney

Parathyroid hormone (PTH) dependent cyclic AMP (cAMP) accumulation was evaluated in renal cortex from 2- and 12-month-old rats. Basal cAMP was lower, and responses to PTH were greater at all concentrations of hormone in kidney from 2-month-old rats. This difference was obliterated by prior removal of parathyroid glands. cAMP responses to calcitonin and both basal and hormone-stimulated adenylate cyclase activity were the same at both ages. The results suggest progressive loss of responsiveness to PTH with age, but at a site other than the receptor-adenylate cyclase complex. Blunted cAMP accumulation in year-old rats most likely reflects agonist-specific desensitization.