Distributions of alcohol use and alcohol-caused death and disability in Canada: Defining alcohol harm density functions and new perspectives on the prevention paradox

AIMS

The aims of this study were to examine the distribution of alcohol use and to define 'harm density functions' representing distributions of alcohol-caused health harm in Canada, by sex, towards better understanding which groups of drinkers experience the highest aggregate harms.

DESIGN

This was an epidemiological modeling study using survey and administrative data on alcohol exposure, death and disability and risk relationships from epidemiological meta-analyses.

SETTING

This work took place in Canada, 2019.

PARTICIPANTS

Canadians aged 15 years or older participated.

MEASUREMENTS

Measures included modeled life-time mean daily alcohol use in grams of pure alcohol (ethanol) per day, alcohol-caused deaths and alcohol-caused disability-adjusted life-years.

FINDINGS

As a life-time average, more than half of Canadians aged 15+ (62.8% females, 46.9% males) use fewer than 10 g of pure alcohol per day (g/day). By volume, the top 10% of the population consume 45.9% of the total ethanol among males and 47.1% of the total ethanol among females. The remaining 90% of the population experience a slim majority of alcohol-caused deaths (males 55.3%, females 46.9%). Alcohol harm density functions compose the size of the using population and the risk experienced at each volume level to show that the population-level harm experienced is highest for males at 25 g/day and females at 13 g/day.

CONCLUSIONS

Almost 50% of alcohol use in Canada is concentrated among the highest 10% of drinkers, but more than half of the alcohol-caused deaths in Canada in 2019 were experienced by the bottom 90% of the population by average volume, providing evidence for the prevention paradox. New alcohol harm density functions provide insight into the aggregate health harm experienced across the mean alcohol use spectrum and may therefore be used to help determine where alcohol policies should be targeted for highest efficacy.

A drink equals how many cigarettes? Equating mortality risks from alcohol and tobacco use in Canada

Objective

To quantify and communicate risk equivalencies for alcohol-and tobacco-attributable mortality by comparing per standard drinks consumed to per number of cigarettes smoked in Canada.

Methods

Alcohol-and tobacco-attributable premature deaths (≤75 years of age) and years of life lost (YLL) were estimated using a lifetime risk modeling approach. Alcohol-attributable death statistics were obtained from the 2023 Canadian Guidance on Alcohol and Health data source. Tobacco-attributable death statistics were derived from the Mortality Population Risk Tool (MPoRT) model.

Results

The risk of alcohol use on premature death and YLL increased non-linearly with the number of drinks consumed, while the risk for tobacco use on these two measures increased linearly with the number of cigarettes smoked. Males who consumed 5 drinks/day-a standard drink contains 13.45 grams of alcohol in Canada-had an equivalent risk as smoking 4.9 cigarettes/day (when modeling for premature death) and 5.1 cigarettes/day (when modeling for YLL). Females who consumed 5 drinks/day experienced an equivalent risk as smoking 4.2 cigarettes/day for premature deaths and YLL. At all levels of alcohol consumption females and males who consumed <5 drinks/day have less risks from consuming a standard drink than from smoking a cigarette. For males who consumed 5 drinks/day, the increased risks of death from per drink consumed and per cigarette smoked were equal.

Conclusion

Risk equivalencies comparing alcohol use to tobacco use could help people who drink improve their knowledge and understanding of the mortality risks associated with increased number of drinks consumed per day.

The public-private decision for alcohol retail systems: Examining the economic, health, and social impacts of alternative systems in Finland

Background: Organising alcohol retail systems with more or less public ownership has implications for health and the economy. The aim of the present study was to estimate the economic, health, and social impacts of alcohol use in Finland in 2018 (baseline), and in two alternative scenarios in which current partial public ownership of alcohol retail sales is either increased or fully privatised. Methods: Baseline alcohol-attributable harms and costs were estimated across five categories of death, disability, and criminal justice. Two alternate alcohol retail systems were defined as privately owned stores selling: (1) only low strength alcoholic beverages (public ownership scenario, similar to Sweden); or (2) all beverages (private ownership scenario). Policy analyses were conducted to estimate changes in alcohol use per capita. Health and economic impacts were modelled using administrative data and epidemiological modelling. Results: In Finland in 2018, alcohol use was estimated to be responsible for €1.51 billion (95% Uncertainty Estimates: €1.43 billion, €1.58 billion) in social cost, 3,846 deaths, and 270,652 criminal justice events. In the public ownership scenario, it was estimated that alcohol use would decline by 15.8% (11.8%, 19.7%) and social cost by €384.3 million (€189.5 million, €559.2 million). Full privatisation was associated with an increase in alcohol use of 9.0% (6.2%, 11.8%) and an increase in social cost of €289.7 million (€140.8 million, €439.5 million). Conclusion: The outcome from applying a novel analytical approach suggests that more public ownership of the alcohol retail system may lead to significant decreases in alcohol-caused death, disability, crime, and social costs. Conversely, full privatisation of the ownership model would lead to increased harm and costs.

What proportion of the price of a typical alcoholic beverage is taxation in Canada and why does it matter?

INTRODUCTION

Canadian distillers and brewers have claimed that between 50% and 80% of the price of alcoholic drinks are government taxes. These claims were made in campaigns to decrease alcohol taxation.

METHODS

We investigated these claims using publicly available Statistics Canada data and provincial-level product sales data and breakdowns of the prices of typical alcohol beverages in major market sectors.

RESULTS

In all cases, the rate of total sales tax and excise taxation are mostly between 20% and 30% of final retail prices, well below the industry claims.

The Potential Health Impact of an Alcohol Minimum Unit Price in Québec: An Application of the International Model of Alcohol Harms and Policies

OBJECTIVE

Alcohol minimum unit pricing is a strategy capable of reducing alcohol-related harm from cheap alcoholic beverages. We used the International Model of Alcohol Harms and Policies (InterMAHP), an open-access alcohol harms estimator and policy scenario modeler, to estimate the potential health benefits of introducing minimum unit pricing in Québec, Canada.

METHOD

Aggregated mortality and hospitalization data were obtained from official administrative sources. Alcohol sales and pricing data were obtained from the partial government retail monopoly and Nielsen. Exposure data were from the Canadian Substance Use Exposure Database. Average price changes under two minimum-unit-pricing scenarios were estimated by applying a product-level pricing analysis. The online InterMAHP tool was used to automate the estimation of observed alcohol-attributable harm and what was projected in each policy scenario.

RESULTS

Alcohol was estimated to cause 2,850 deaths and 24,694 hospitalizations in Québec in 2014. Introducing minimum unit pricing of CAD$1.50 was estimated to reduce consumption by 4.4%, alcohol-attributable deaths by 5.9% (95% CI [0.2%, 11.7%]), and alcohol-attributable hospital stays by 8.4% (95% CI [3.2%, 13.7%]). Higher minimum unit pricing of CAD$1.75 was estimated to reduce alcohol-attributable deaths by 11.5% (95% CI [5.9%, 17.2%]) and alcohol-attributable hospital stays by 16.3% (95% CI [11.2%, 21.4%]).

CONCLUSIONS

The results of this policy modeling study suggest that the introduction of minimum unit pricing between CAD$1.50 and $1.75 would substantially reduce the alcohol-caused burden of disease in Québec. The quantification of alcohol-caused death and disability, and the changes in these measures under two scenarios, was significantly automated by the open-access resource, InterMAHP.

How many alcohol-attributable deaths and hospital admissions could be prevented by alternative pricing and taxation policies? Modelling impacts on alcohol consumption, revenues and related harms in Canada

INTRODUCTION

In 2017, Canada increased alcohol excise taxes for the first time in over three decades. In this article, we describe a model to estimate various effects of additional tax and price policies that are predicted to improve health outcomes.

METHODS

We obtained alcohol sales and taxation data for 2016/17 for all Canadian jurisdictions from Statistics Canada and product-level sales data for British Columbia. We modelled effects of alternative price and tax policies - revenue-neutral taxes, inflation-adjusted taxes and minimum unit prices (MUPs) - on consumption, revenues and harms. We used published price elasticities to estimate impacts on consumption and revenue and the International Model for Alcohol Harms and Policies (InterMAHP) to estimate impacts on alcohol-attributable mortality and morbidity.

RESULTS

Other things being equal, revenue-neutral alcohol volumetric taxes (AVT) would have minimal influence on overall alcohol consumption and related harms. Inflation-adjusted AVT would result in 3.83% less consumption, 329 fewer deaths and 3762 fewer hospital admissions. A MUP of $1.75 per standard drink (equal to 17.05mL ethanol) would have reduced consumption by 8.68% in 2016, which in turn would have reduced the number of deaths by 732 and the number of hospitalizations by 8329 that year. Indexing alcohol excise taxes between 1991/92 and 2016/17 would have resulted in the federal government gaining approximately $10.97 billion. We estimated this could have prevented 4000-5400 deaths and 43 000-56 000 hospitalizations.

CONCLUSION

Improved public health outcomes would be made possible by (1) increasing alcohol excise tax rates across all beverages to compensate for past failures to index rates, and (2) setting a MUP of at least $1.75 per standard drink. While reducing alcohol-caused harms, these tax policies would have the added benefit of increasing federal government revenues.

The International Model of Alcohol Harms and Policies: A New Method for Estimating Alcohol Health Harms With Application to Alcohol-Attributable Mortality in Canada

OBJECTIVE

Data regarding alcohol-caused health harms are required by policymakers for setting health priorities. However, these estimations are currently resource intensive, and estimates vary substantially by method. Thus, many countries, states, and regions do not track these harms. We address this limitation through creation of the International Model of Alcohol Harms and Policies (InterMAHP), an open-access alcohol harms estimator. InterMAHP consists of methodologies and program software designed to assist alcohol research teams in estimating alcohol-attributable mortality and morbidity, by region. It is available at www.intermahp.cisur.ca. Application is illustrated through updated estimates of alcohol-attributable mortality in Canada.

METHOD

Mortality counts and per capita alcohol sales were obtained from Statistics Canada. Drinking and bingeing prevalences were obtained from the Canadian Substance Use Exposure Database. InterMAHP automated the calculations of alcohol-attributable fractions (AAF) using the modern AAF formulation and a gamma distribution to specify the continuous prevalence distribution of consumption.

RESULTS

Alcohol is a leading driver of mortality in Canada. In 2016, more than 14,800 (95% CI [12,435, 17,127]) deaths were alcohol attributable, representing 5.5% of all deaths. This burden is borne disproportionately by men (79%). Among condition categories, cancer is the leading cause of alcohol-attributable mortality in both men and women.

CONCLUSIONS

InterMAHP has the potential to assist public health researchers globally in estimating alcohol harms. This open-access software was used to estimate alcohol-attributable mortality in Canada, which was shown to be substantial. Policies proven to reduce alcohol consumption and related harms should be considered to reduce this burden.

Does Drinking Within Low-Risk Guidelines Prevent Harm? Implications for High-Income Countries Using the International Model of Alcohol Harms and Policies

OBJECTIVE

Many countries propose low-risk drinking guidelines (LRDGs) to mitigate alcohol-related harms. North American LRDGs are high by international standards. We applied the International Model of Alcohol Harms and Policies (InterMAHP) to quantify the alcohol-caused harms experienced by those drinking within and above these guidelines. We customized a recent Global Burden of Disease (GBD) analysis to inform guidelines in high-income countries.

METHOD

Record-level death and hospital stay data for Canada were accessed. Alcohol exposure data were from the Canadian Substance Use Exposure Database. InterMAHP was used to estimate alcohol-attributable deaths and hospital stays experienced by people drinking within LRDGs, people drinking above LRDGs, and former drinkers. GBD relative risk functions were acquired and weighted by the distribution of Canadian mortality.

RESULTS

More men (18%) than women (7%) drank above weekly guidelines. Adherence to guidelines did not eliminate alcohol-caused harm: those drinking within guidelines nonetheless experienced 140 more deaths and 3,663 more hospital stays than if they had chosen to abstain from alcohol. A weighted relative risk analysis found that, for both women and men, the risk was lowest at a consumption level of 10 g per day. For all levels of consumption, men were found to experience a higher weighted relative risk than women.

CONCLUSIONS

Drinkers following weekly LRDGs are not insulated from harm. Greater than 50% of alcohol-caused cancer deaths are experienced by those drinking within weekly limits. Findings suggest that guidelines of around one drink per day may be appropriate for high-income countries.

Expanding attributable fraction applications to outcomes wholly attributable to a risk factor

The problem central to this document is the estimation of change in disease attributable to an epidemiological exposure variable that stems from a change in the distribution of that variable. We require that both disease and exposure are quantifiable as real numbers, and then ask how to estimate the fraction of disease attributable to exposure, producing the general attributable fraction methodology. After the mathematical framework is in place, we explore the implications of a disease that is wholly attributable to a given risk factor, demonstrate why standard applications of the attributable fractions do not extend, and present general methodological considerations for this case. Finally, we demonstrate the methodology using the example of alcoholic psychoses.

Implications of Cardioprotective Assumptions for National Drinking Guidelines and Alcohol Harm Monitoring Systems

The existence and potential level of cardioprotection from alcohol use is contested in alcohol studies. Assumptions regarding the risk relationship between alcohol use and ischaemic heart disease (IHD) are critical when providing advice for national drinking guidelines and for designing alcohol harm monitoring systems. We use three meta-analyses regarding alcohol use and IHD risk to investigate how varying assumptions lead to differential estimates of alcohol-attributable (AA) deaths and weighted relative risk (RR) functions, in Australia and Canada. Alcohol exposure and mortality data were acquired from administrative sources and AA fractions were calculated using the International Model of Alcohol Harms and Policies. We then customized a recent Global Burden of Disease (GBD) analysis to inform drinking guidelines internationally. Australians drink slightly more than Canadians, per person, but are also more likely to identify as lifetime abstainers. Cardioprotective scenarios resulted in substantial differences in estimates of net AA deaths in Australia (between 2933 and 4570) and Canada (between 5179 and 8024), using GBD risk functions for all other alcohol-related conditions. Country-specific weighted RR functions were analyzed to provide advice toward drinking guidelines: Minimum risk was achieved at or below alcohol use levels of 10 g/day ethanol, depending on scenario. Consumption levels resulting in 'no added' risk from drinking were found to be between 10 and 15 g/day, by country, gender, and scenario. These recommendations are lower than current guidelines in Australia, Canada, and some other high-income countries: These guidelines may be in need of downward revision.

Proscriptive vs. Prescriptive Health Recommendations to Drink Alcohol Within Recommended Limits: Effects on Moral Norms, Reactance, Attitudes, Intentions and Behaviour Change

Aims

Health advice can be framed in terms of prescriptive rules (what people should do, e.g. you should drink alcohol within recommended limits) or proscriptive rules (what people should not do, e.g. you should not drink alcohol above recommended limits). The current research examines the differing effect that these two types of injunction have on participants' moral norms, reactance, attitudes and intentions to consume alcohol within moderation, and their subsequent alcohol consumption.

Methods

Participants (N = 529) completed an online questionnaire which asked them to report their previous 7 days' alcohol consumption. They then read either a proscriptive or a prescriptive health message and completed measures of moral norms, reactance, attitudes and intentions to drink alcohol only within recommended limits. Subsequent alcohol consumption was reported 7 days later.

Results

The results showed that across all participants, the proscriptive message elicited stronger moral norms than did the prescriptive message, which in turn were associated with more positive attitudes and intentions to drink within recommended limits. For male participants who reported drinking more alcohol than recommended at baseline, the proscriptive message elicited more reported alcohol consumption over the subsequent 7 days.

Conclusions

Proscriptive messages may be effective at eliciting stronger moral norms to drink within government recommended guidelines. However, reactance may occur for high relevance groups. Practical and theoretical implications are discussed.

Pregnancy after heterotopic heart transplant removal

Heterotopic heart transplants were introduced in 1974. The technique allows the patient's native heart to be preserved in situ, alongside the transplanted heterotopic donor heart. We present the case of a nulliparous woman who underwent heterotopic heart transplant in infancy, and subsequent explantation of the donor heart eleven years later, when her native heart function recovered. In adulthood the patient attended pre-pregnancy counselling and was awaiting cardiac magnetic resonance imaging when she presented pregnant at 6 weeks-of-gestation. She attended the joint cardiac obstetric and anaesthetic clinic, where she was reviewed monthly and had bi-monthly echocardiograms. At 35 weeks-of-gestation she was admitted to hospital with preeclampsia. After blood pressure control and steroid administration, a category 3 caesarean delivery under spinal anaesthesia was performed. To our knowledge this is the first case report describing pregnancy in a patient with a removed heterotopic heart transplant.

Predictors of severe outcomes associated with Clostridium difficile infection in patients with inflammatory bowel disease

BACKGROUND

The increasing incidence of Clostridium difficile (C. difficile) infection (CDI) among patients with inflammatory bowel disease is well recognised. However, most studies have focused on demonstrating that CDI is associated with adverse outcomes in IBD patients. Few have attempted to identify predictors of severe outcomes associated with CDI among IBD patients.

AIM

To identify clinical and laboratory factors that predict severe outcomes associated with CDI in IBD patients.

METHODS

From a multi-institution EMR database, we identified all hospitalised patients with at least one diagnosis code for C. difficile from among those with a diagnosis of Crohn's disease or ulcerative colitis. Our primary outcome was time to total colectomy or death with follow-up censored at 180 days after CDI. Cox proportional hazards models were used to identify predictors of the primary outcome from among demographic, disease-related, laboratory and medication variables.

RESULTS

A total of 294 patients with CDI-IBD were included in our study. Of these, 58 patients (20%) met our primary outcome (45 deaths, 13 colectomy) at a median of 31 days. On multivariate analysis, serum albumin <3 g/dL (HR 5.75, 95% CI 1.34-24.56), haemoglobin below 9 g/dL (HR 5.29, 95% CI 1.58-17.69) and creatinine above 1.5 mg/dL (HR 1.98, 95% CI 1.04-3.79) were independent predictors of our primary outcome. Examining laboratory parameters as continuous variables or shortening our primary outcome to include events within 90 days yielded similar results.

CONCLUSION

Serum albumin below 3 g/dL, haemoglobin below 9 g/dL and serum creatinine above 1.5 mg/dL were independent predictors of severe outcomes in hospitalised IBD patients with Clostridium difficile infection.

Pulmonary edema associated with hyperbaric oxygen therapy

We report three cases of pulmonary edema associated with hyperbaric oxygen therapy, including one fatality. All three patients had cardiac disease and reduced left ventricular (LV) ejection fractions (EFs). Two patients had diabetes, and one patient had severe aortic stenosis. Hyperbaric oxygen therapy may contribute to pulmonary edema by increasing LV afterload, increasing LV filling pressures, increasing oxidative myocardial stress, decreasing LV compliance by oxygen radical-mediated reduction in nitric oxide, altering cardiac output between the right and left hearts, inducing bradycardia with concomitant LV dysfunction, increasing pulmonary capillary permeability, or by causing pulmonary oxygen toxicity. We advise caution in the use of hyperbaric oxygen therapy in patients with heart failure or in patients with reduced cardiac EFs.

Minority recruitment in clinical trials: a conference at Tuskegee, researchers and the community

PURPOSE

This article describes the planning, implementation, and evaluation of a 2-day conference designed to examine the factors related to the participation of African Americans in cancer clinical trials.

METHODS

Pre-conference formative evaluations (e.g., focus group discussions and key informant interviews with community leaders and health providers) were conducted in several rural and urban counties in the state of Alabama to determine African Americans' perceptions of participation in clinical research. The findings from these evaluations were used to develop a conference format and agenda. The 2-day conference included: (i) a pretest of African Americans' perceptions of cancer research, participation factors, and communication and recruitment issues; (ii) individual presentations high-lighting community leaders, church leaders, and researchers' perspectives regarding minority participation in research; (iii) working group discussions regarding the barriers and solutions to minority participation in research; and (iv) a posttest evaluation to measure changes in African Americans' perceptions of research.

RESULTS

Several recruitment barriers and solutions were identified and reported by the working groups. Comparisons of the pretest and posttest measures showed significant (p > .05) and favorable shifts in the areas of perceptions of cancer research, participation factors, communication issues, and recruitment issues. Participation in the conference reflected a positive change in attitudes on these measures. However, the theme, "barriers that contributed to nonparticipation," did not show any significant changes during the two testing periods. The most critical lesson that resulted from this conference was the need for researchers and community members to have open dialogue about participation in research.

CONCLUSIONS

This conference demonstrated that progress can be made when all parties are at the "table" and can be heard. In this model, community members proved to be valuable resources in providing researchers with information that was vital to the success of recruitment and retention studies and trials.

Performance of the Baxter Flo-Gard 6201 volumetric infusion pump for monoplace chamber applications

For non-hyperbaric purposes, the Baxter Flo-Gard 6201 volumetric pump is capable of infusing multiple types of fluids at rates of 1-1,999 ml x h(-1). We designed a study to determine flow accuracy of this pump at variable rates, fluid viscosities, and volumes over a range of chamber pressures. For hyperbaric use, the pump pressure sensor was adjusted. Sodium chloride solution 0.9% (NS), enteral formula, and packed red blood cells (PRBC) were infused at varying rates from 86.1 to 304 kPa (0.85 to 3.0 atm abs). For NS, measured compared to set flow rates ranged from 12.5% to -7.5% at settings of 1 and 5 ml x h(-1) from 86.1 to 304 kPa (0.85 to 3.0 atm abs) pressures, respectively. For NS infusions at a set rate of 100 ml x h(-1), the measured flow was identical to the set rate at all pressures. At flow settings of 1,999 ml x h(-1), the measured flow varied from the set flow by +/-4.9% Enteral infusion at 100 ml x h(-1) showed approximately a 3% increase in the measured vs. set flow rate. PRBC measured flow rates ranged from -0.4 to 6% of the set rate. During chamber compression and decompression, with set flow rates from 1 to 10 ml x h(-1), the measured flow was considerably less than expected during compression and more than expected during decompression. In conclusion, the Baxter Flo-Gard 6201 infusion pump demonstrated acceptable performance for infusing saline, enteral formula, and PRBC at low and high infusion rates into the pressurized monoplace hyperbaric chamber up to 304 kPa (3 atm abs), with the exception of low rates during compression and decompression.

Purification and characterization of a (R)-3-hydroxybutyrate dehydrogenase deletion mutant. Evidence for C-terminal involvement in enzyme activation by lecithin

(R)-3-Hydroxybutyrate dehydrogenase (BDH; EC 1.1.1.30) is a lipid-requiring enzyme with a specific requirement of phosphatidylcholine for optimal function. The purified enzyme, devoid of lipid, can be reactivated with soluble lecithin or by insertion into phospholipid vesicles containing lecithin. In order to obtain insight into the mechanism of lipid activation, a C-terminal deletion mutant was constructed which contained 18 amino acids less than BDH. The purified deletion mutant had low, but detectable catalytic activity in the absence of phospholipid. However, the addition of either soluble lecithin or phospholipid vesicles containing lecithin had no effect on enzymatic function. Further experiments were conducted to determine if the deletion mutant had also lost its ability to bind to phospholipid vesicles and natural membranes. Our findings indicate that the mutant enzyme binds to both liposomes and rat liver microsomes. These results suggest that the binding of BDH to the phosphatidylcholine head group is independent of its interaction with the apolar core of the phospholipid bilayer.

Habitat Use, Distribution and Conservation Status of The Nabarlek, Petrogale concinna, and Sympatric Rock-Dwelling Mammals, in The Northern Territory

A survey of the distribution of the Nabarlek (Petrogale concinna) in the Top End of the Northern Territory found the species to be trap shy, secretive and often difficult to distinguish from sympatric Petrogale brachyotis in the field. The small number of records for the species is probably attributable to these characteristics. Habitat preferences appeared to be broad with the species utilising a range of rocky environments from the steep and rugged cliffs of the Arnhem Land escarpment to the low granite boulder hills of the Mary River region. The presence of P. concinna was correlated primarily with the availability of steep slopes and the presence of a large number of caves. The presence of P. concinna was examined in relation to the presence and abundance of 18 species of sympatric mammals. During the study P. concinna was recorded from 8 localities, and although further work is required, the species conservation status appears to be secure.

Feeding Behaviour and Food Availability of the Yellow-Bellied Glider in North Queensland

The diet of the yellow-bellied glider (Petaurus australis) was examined at a site in north Queensland by extensive observation of individuals from 10 glider groups. The diet was assessed in four seasons over 12 months by collating large numbers of qualitative feeding observations and by analysis of faeces. Data were also collected on flowering and bark shedding in the forest. Sap feeding accounted for more than 80% of the feeding observations throughout the year. Nectar and pollen of eucalypts (Eucalyptus spp.) and banksias (Banksia spp.) accounted for much of the remainder of the diet although arthropods and honeydew were present in spring and summer. Faecal analysis was based on much smaller sample sizes but confirmed the qualitative result obtained from direct observations. It also revealed the presence of a wide variety of pollen types. Many of these could be attributed to incidental ingestion but at least six rain forest genera were moderately common in faeces, which is consistent with observations of brief and infrequent visits by gliders to these trees. Examination of eucalypt, banksia and other pollen types showed that 60-70% of pollen was devoid of cell contents, supporting earlier suggestions that gliders obtained protein from pollen digestion, but at this site also from harvesting arthropods. This study confirms the dependence of the yellow-bellied glider in north Queensland on the sap of the red stringybark (Eucalyptus resinifera) and that conservation of the yellow-bellied glider is intimately associated with the management of this tree species. The use of various species for nectar and pollen suggests that the yellow-bellied glider may be an important pollinator in these forests. Moreover, sap from the wounds created by gliders is used by a range of other animal species. These observations suggest that the yellow-bellied glider is likely to be a keystone species in the open-forest ecosystems of north Queensland and that it deserves special emphasis in management.

Purification and characterization of D-beta-hydroxybutyrate dehydrogenase expressed in Escherichia coli

D-beta-Hydroxybutyrate dehydrogenase (BDH), a lipid-requiring enzyme, has been cloned into pUC18, expressed in Escherichia coli, and purified to homogeneity. The apoenzyme, i.e., the enzyme devoid of phospholipid, has no activity, but can be activated by phospholipid to a specific activity of 129 mumol/(min.mg). The functional properties of the enzyme expressed in E. coli were compared with the enzyme purified from rat liver. The specific activities, kinetic parameters, and phospholipid activation profiles were virtually identical. These results indicate that the expression of the enzyme in E. coli is a viable method for producing active functional BDH and should allow for the production of specifically altered BDH molecules.

Effects of repeated gestation and lactation on milk n-6 fatty acid composition in rats fed on a diet rich in 18:2n-6 or 18:3n-6

The present study examined the effect of repeated gestation and lactation on the levels of long-chain n-6 polyunsaturated fatty acids in rat milk fat, and examined whether such levels might be modulated by supplementing the diet of the lactating dams with either (g/kg) 50 safflower oil (SFO; containing 800 g 18:2n-6/kg), or 50 evening primrose oil (EPO; containing 720 g 18:2n-6 and 90 g 18:3n-6/kg). The milk was collected at three different times (days 1, 8 and 15) in each given lactation period from female Sprague-Dawley rats which were successively bred for four pregnancies and lactations. Results showed that dietary fat and breeding frequency had no significant effects on milk triacylglycerol content, but they modified the pattern of milk fatty acids in both triacylglycerol and phospholipid fractions. After three or four successive breedings rats fed on EPO produced milk containing less saturated but more monounsaturated and polyunsaturated fatty acids compared with those fed on SFO. During the course of lactation the levels of n-6 metabolites, e.g. 18:3n-6, 20:3n-6 and 20:4n-6, in milk fat declined progressively. However, they were consistently higher in the EPO group than in the SFO group. These findings suggest that the levels of long-chain n-6 metabolites in the milk fat may be increased through supplementing the maternal diet with 18:3n-6.

Primary structure of rat liver D-beta-hydroxybutyrate dehydrogenase from cDNA and protein analyses: a short-chain alcohol dehydrogenase

The amino acid sequence of D-beta-hydroxybutyrate dehydrogenase (BDH), a phosphatidyl-choline-dependent enzyme, has been determined for the enzyme from rat liver by a combination of nucleotide sequencing of cDNA clones and amino acid sequencing of the purified protein. This represents the first report of the primary structure of this enzyme. The largest clone contained 1435 base pairs and encoded the entire amino acid sequence of mature BDH and the leader peptide of precursor BDH. Hybridization of poly(A+) rat liver mRNA revealed two bands with estimated sizes of 3.2 and 1.7 kb. A computer-based comparison of the amino acid sequence of BDH with other reported sequences reveals a homology with the superfamily of short-chain alcohol dehydrogenases, which are distinct from the classical zinc-dependent alcohol dehydrogenases. This protein family, initially discerned from Drosophila alcohol dehydrogenase and bacterial ribitol dehydrogenase, is now known to include at least 20 enzymes catalyzing oxidations of distinct substrates.

Cloning and expression of a functional rat liver D-beta-hydroxybutyrate dehydrogenase-beta-galactosidase fusion protein in Escherichia coli

A rat liver bacteriophage lambda expression library was probed using polyclonal antibodies raised to purified rat liver D-beta-hydroxybutyrate dehydrogenase (BDH). A clone was selected that contained a 1.2-kb insert. The insert placed in an expression plasmid was utilized to transform Escherichia coli. These cells were shown to possess phosphatidylcholine-dependent BDH activity. Cells transformed with only the plasmid had no detectable BDH activity in the presence of phosphatidylcholine. The expressed activity in E. coli could be inhibited in a dose-dependent manner by BDH antiserum.

Comparison of D-beta-hydroxybutyrate dehydrogenase from rat liver and brain mitochondria

The properties of D-beta-hydroxybutyrate dehydrogenase (BDH) from rat liver and brain mitochondria were compared to determine if isozymes of this enzyme exist in these tissues. The BDHs from these tissues behaved similarly during the purification process. The enzymes were indistinguishable by sodium dodecyl sulfate-polyacrylamide or acid-urea-polyacrylamide gel electrophoresis and they had identical isoelectric points. The BDHs from rat liver and brain were also quite similar in functional parameters determined by kinetic analysis and phospholipid activation of apo-BDH (i.e., the lipid-free enzyme). Antiserum against rat liver BDH inhibited both enzymes to an equivalent extent in a titration assay. The enzymes had similar patterns of peptide mapping by partial digestion with Staphylococcus aureus V8 protease, followed by immunoblotting using antiserum against the liver enzyme. These results suggest that the BDHs in rat liver and brain are very similar and possibly identical.

Developmental regulation of D-beta-hydroxybutyrate dehydrogenase in rat liver and brain

The activities of ketone-metabolizing enzymes in rat brain increase 3- to 5-fold during the suckling period before decreasing to the adult level after weaning. We have observed that a similar developmental pattern also exists for D-beta-hydroxybutyrate dehydrogenase (BDH) in rat liver. Utilizing antibodies prepared against the purified protein we determined that the changes in BDH activities in both brain and liver are due to changes in the amount of BDH in the mitochondria. In vitro translations of isolated RNA followed by immunoprecipitation revealed that the increase in BDH activity and content was correlated with an increase in the level of functional BDH-mRNA in both liver and brain.

Regulation of D-beta-hydroxybutyrate dehydrogenase in rat hepatoma cell lines

Quantitation of D-beta-hydroxybutyrate dehydrogenase (BDH) in normal rat hepatocytes was compared with that in two rat hepatoma cell lines, H4-II-EC3 and RLT-3C. BDH activity in normal rat hepatocyte mitochondria was 321 nmol/min/mg, which was greatly reduced to 10.7 nmol/min/mg and 1.7 nmol/min/mg in H4-II-EC3 and RLT-3C cell mitochondria, respectively. The cell growth rate and L-[35S]methionine incorporation rate showed that RLT-3C cells had the highest growth rate (32.4-h doubling time) and the fastest protein biosynthesis rate (2.65 x 10(5) cpm/min/10(6) cells). The H4-II-EC3 cell line grew more slowly (48.5-h doubling time) and had lower protein biosynthesis rate (1.46 x 10(5) cpm/min/10(6) cells). The protein synthesis rate in hepatocytes was 1.25 x 10(5) cpm/min/10(6) cells. These results suggest that there is a reciprocal correlation between BDH activity and cell growth and protein synthesis rates. Immunochemical quantitation of BDH showed the amount of BDH in H4-II-EC3 and RLT-3C cells was about 4.8 and 0.5% of that in normal rat hepatocytes, respectively. Quantitation of BDH by biosynthesis indicated that BDH content in H4-II-EC3 cells and RLT-3C cells was 9.3 and 4.0% of that of normal hepatocytes, respectively. Precursor BDH synthesized by in vitro translation primed with RNA of H4-II-EC3 cells or RLT-3C cells was 3.0 and 1.1% of that translated from normal rat hepatocyte RNA. These results suggest that the decrease in BDH content in hepatoma cells results from a decrease in functional BDH-mRNA. The coupling of a decrease in BDH activity with an increase in activity of succinyl-CoA: acetoacetyl-CoA transferase in hepatoma cells may play a role in generating additional energy required for the rapid growth of tumor cells.

Vasopressin antagonism in the squirrel monkey (Saimiri sciureus)

Vasopressin antagonism and water diuresis (aquaresis) is demonstrated after i.p. or i.v. administration of vasopressin antagonists in a primate species, the squirrel monkey (Saimiri sciureus). Antagonism of vasopressin-stimulated renal medullary adenylate cyclase activity was evaluated in vitro; the most potent antagonists were those with D-tyrosine (alkyl) substitutions at position 2. Aquaresis was evaluated in vivo; the most potent aquaretic agents were again those with D-tyrosine (alkyl) substitutions at position 2. Correlation of in vitro vasopressin antagonist and in vivo aquaretic potencies for a series of antagonists was r = 0.7880 (P less than .05). Renal excretion of electrolytes, creatinine and urea tended to increase slightly as a function of vasopressin antagonist dose; the rates of solute excretion approached but seldom exceeded those rates associated with water diuresis in squirrel monkeys. The vasopressin antagonists antagonized the antidiuretic activity of exogenous vasopressin in vivo. Onset of the aquaretic response to i.v. administration of desGlyd(CH2)5D-Tyr(Et)VAVP was within 30 min; duration was greater than 120 min. These studies establish vasopressin antagonism and aquaresis associated with administration of vasopressin antagonists in a primate species.

Characterization of purified rabbit uterine renin: influence of pregnancy on uterine inactive renin

Using specific antibody raised against renal renin, we have documented that the majority of the uterine renin-like activity in gravid and nongravid uteri is immunoreactive renin. To characterize its physiochemical properties, we obtained highly purified uterine renin by two affinity chromatographic steps, pepstatin and antirenin. Uterine renin has a pH optimum of 6, an apparent mol wt of 38K, and a Km of 1.7 microM for homologous substrate. These properties are identical to those of renal renin and are not influenced by the pregnant state. In the basal state, an inactive form of the uterine enzyme constitute 55 +/- 10% of the total uterine renin. During pregnancy, active renin increased 40-fold as inactive renin fell to 4 +/- 3% of the total renin concentration. The renal renin concentration fell as plasma renin increased during pregnancy. These data suggest that the increased uterine renin concentrations during pregnancy are probably due to increased local production and conversion of renin precursor to the active enzyme. This stimulation of the uterine renin level appears to be independent of renal renin.

Phospholipid protection against proteolysis of D-beta-hydroxybutyrate dehydrogenase, a lecithin-requiring enzyme

D-beta-Hydroxybutyrate dehydrogenase is a lipid-requiring enzyme which is localized on the inner face of the mitochondrial inner membrane. The apodehydrogenase, i.e. the purified enzyme devoid of lipid, has been purified from beef heart mitochondria and as such is inactive. It can be reactivated by insertion into phospholipid vesicles containing lecithin. Proteolytic digestion with different proteases has been carried out to obtain insight into the orientation of the enzyme in the membrane and to assess the extent of immersion of the protein into the phospholipid bilayer. Digestion of the apodehydrogenase with either trypsin, chymotrypsin, Staphylococcus aureus protease, thermolysin, carboxypeptidases A and Y, or Pronase (from Streptomyces griseus) leads to loss of activity, as assayed with phospholipid. Limited digestion with carboxypeptidase results in complete inactivation. Of the proteases tested, only Pronase and chymotrypsin cleave and inactivate the enzyme inserted into phospholipid vesicles (enzyme-phospholipid complex). For the enzyme-phospholipid complex, the loss of activity with Pronase digestion follows a single exponential decay to less than 10% of the initial activity. With chymotrypsin digestion, the staining intensity of the original approximately 31,500-dalton polypeptide decreases more rapidly than the loss of enzymic activity. The enzyme-phospholipid complex, after limited cleavage with chymotrypsin, retains enzymic activity and resonance energy transfer from protein to bound NADH and an approximately 26,000-dalton polypeptide is observed. Phospholipid alters the cleavage pattern with both chymotrypsin and Pronase, and the rate of inactivation of the enzyme-phospholipid complex is slowed in the presence of NAD(H). Moreover, the rate of inactivation of the apodehydrogenase with chymotrypsin is diminished approximately 3-fold in the presence of NAD+. Digestion of submitochondrial vesicles with either trypsin, chymotrypsin, or Pronase rapidly inactivates D-beta-hydroxybutyrate dehydrogenase; the addition of NAD+ or NADH, together with dithiothreitol and increased salt (to 50 mM), decreases the rate of inactivation, and with trypsin, virtually eliminates inactivation.(ABSTRACT TRUNCATED AT 400 WORDS)

Role of aldosterone in sodium retention of pregnancy in the rat

The purpose of this study was to test whether the absence or inhibition of aldosterone would alter the Na retention of pregnancy in the rat. We performed metabolic balance studies during the last 2 wk of the 3-wk rat pregnancy in the following four groups of saline-drinking rats: nonpregnant, sham adrenalectomized; pregnant, sham adrenalectomized; nonpregnant, adrenalectomized; and pregnant, adrenalectomized. Significant net Na retention was not found during the 2nd wk in any of the groups. During the final week, however, both pregnant groups retained between 8 and 11 meq Na more than their respective control groups. In addition, we measured plasma aldosterone concentration in these rats at term. The mineralocorticoid was not detectable in the nonpregnant adrenalectomized rats but was present in the pregnant adrenalectomized rats at a concentration of about 50% of that found in the pregnant sham-adrenalectomized rats. Serial measurements revealed that aldosterone was measurable by day 18 and nondetectable by 2 days postpartum in these pregnant adrenalectomized rats. Comparable balance studies were also performed in three groups of water-drinking rats: nonpregnant, pregnant, and pregnant rats that received large daily doses of spironolactone. During the 3rd wk both pregnant groups were in significant positive Na balance. Net Na retention for untreated pregnant rats was 8.4 meq and for the spironolactone treated, 6.9 meq, values that were not significantly different. We conclude that is is unlikely that aldosterone plays a critical role in the Na retention found during rat pregnancy.

Renal hemodynamics and volume homeostasis during pregnancy in the rat

We believe that in pregnant rats, GFR is elevated at term, whereas renal plasma flow appears not to be increased. The mechanism for this increment is unclear, as is the specific time during gestation when renal hemodynamics increase. Rats increase their salt appetite and significantly positive sodium balance occurs, which is most pronounced during the last week of gestation. The retained sodium is distributed in part to the products of conception and in part to the mother, particularly in increasing her extracellular fluid volume. Although chronic volume expansion is present, absolute tubular sodium reabsorption remains elevated. The mechanism for this elevated tubular reabsorption appears no to be related to aldosterone because reduction or inhibition of this mineralocorticoid does not affect sodium balance significantly.

Normal renocortical blood flow in experimental acute renal failure

Renal cortical blood flow of rats with postischemic, myohemoglobinuric, and mercury-induced acute renal failure was measured by the hydrogen washout technique using implanted platinum electrodes. Total renal blood flow was determined by venous cannulation in separate series of rats. The values obtained with the two methods were in excellent qualitative agreement (r=0.99, P less than 0.001), although venous cannulation gave values that were constantly lower than those calculated for whole kidney from the cortical flow rate and assumed cortical mass. Myohemoglobinuria produced by glycerol injection caused cortical blood flow to fall from a control value of 7.37+/-0.23 (SEM) ml/min X g of cortex to approximately one-half that value for four hours after injection (P less than 0.001). Flow rates 12 and 24 hr after glycerol injection were 85% (P less than 0.001) and 90% (P less than 0.05) of control, respectively. Cortical flow was reduced to 5.49+/-0.39 (SEM) ml/min X g of cortex four hours after release of one hour's total bilateral renal arterial occlusion (P less than 0.001), but rose to normal within 24 hr. Poisoning with 4.7 mg/kg of body wt of mercuric chloride produced a cortical blood flow value that was 30% higher than control 24 hr after injection (P less than 0.01), while a 12 mg/kg of body wt dose gave a normal flow value. Inulin clearance was severely depressed in all models at all study times. Thus, in contrast to human acute renal failure, marked renal cortical ischemia is not an essential feature of these different forms of murine acute renal failure.