Management and behavioral factors associated with rehoming outcomes of dogs retired from commercial breeding kennels

Rehoming is a potentially stressful process for dogs retired from commercial breeding (CB) kennels, as they may struggle to cope with the myriad novel factors associated with transitioning to a home environment. Failure to adapt may increase the risk of an unsuccessful adoption, jeopardizing dog welfare and the benefits of rehoming programs. Little is known about relationships between welfare in the kennel of origin and a dog's ability to transition to a family home. This study aimed at investigating the welfare states of dogs retiring from CB kennels in relation to varying management practices across kennels, and understanding how behavioral and management factors might be associated with rehoming outcomes. A total of 590 adult dogs from 30 US CB kennels were included in the study. Dog behavioral and physical health metrics were collected through direct observation, while management information was obtained through a questionnaire. One month after adoption, 32 dog owners completed a follow-up questionnaire (CBARQ). A principal component analysis extracted four behavioral components (PCs) which included food interest, sociability, boldness, and responsiveness. Factors such as sex, housing, breed, and the number of dogs per caretaker were reported as significant sources of variation for some of those PC scores (p<0.05). For instance, lower dog to caretaker ratio was linked to better health, sociability, and food interest scores. Significant relationships were also found between in-kennel PC scores and CBARQ scores (p<0.05). Most interestingly, higher levels of sociability in the kennel were associated with lower levels of social and non-social fear, and higher trainability after rehoming. Overall, dogs were found to be physically healthy, and a moderate proportion showed fearful responses toward either social or non-social stimuli. Results suggest that a comprehensive behavioral assessment of rehoming candidates while in the kennel may help identify dogs that may have more difficulty coping during rehoming. The implications for developing management strategies and necessary interventions that support positive dog welfare outcomes within the kennel and when rehomed are discussed.

Use of two novel trailer types for transportation of pigs to slaughter. 1. Effects on trailer microclimate, pig behaviour, physiological response, and meat quality under Canadian summer conditions

A total of 3,366 pigs were transported to slaughter in summer (six replicates/trailer type; July-August in southwestern Ontario) using three trailers: a modified triple-deck pot-belly (MPB), an advanced flat-deck (AFD), and a standard pot-belly (SPB). Within trailers, ambient conditions, temperature (T°C ), relative humidity (RH%), and temperature-humidity-index (THI), were monitored in three compartments (bottom front, BF, middle deck, MM, and top rear, TR). A total of 324 pigs were selected for the analysis of hematocrit, lactate, and creatine kinase (CK) levels in exsanguination blood and for the evaluation of pork quality as assessed in the longissimus (LM), semimembranosus (SM), and adductor (AD) muscles. The AFD and MPB trailers presented lower (P < 0.01) T°C and THI compared to the SPB during transit. In the SPB trailer, pigs transported in the MM compartment showed higher (P < 0.01) blood CK concentrations than those transported in the BF compartment and lower pHu values in the SM and AD muscles (P = 0.02 and P = 0.04, respectively) than those transported in the TR compartment. Although the AFD trailer design provided a better microclimate for pigs, the improvements in the design of the novel trailers only slightly reduced stress in pigs during summer transits.

Use of two novel trailer types for transportation of pigs to slaughter. 2. Effects on trailer microclimate, pig behaviour, physiological response, and meat quality under Canadian winter conditions

In total, 3,654 market pigs were transported to slaughter in winter (six replicates/treatment; January-February in southwestern Ontario) using three trailers: a modified triple-deck pot-belly (MPB), an advanced flat-deck (AFD) trailer, and a standard pot-belly (SPB). Within trailers, ambient conditions, temperature (T°C), relative humidity (RH%) and temperature and humidity index (THI), were monitored in three compartments (bottom front, BF, middle middle deck, MM, and top rear, TR). In total, 324 pigs were selected for the analysis of hematocrit, lactate, and creatine kinase (CK) levels in exsanguination blood and for the evaluation of pork quality as assessed in the longissimus (LM), semimembranosus (SM), and adductor (AD) muscles. The SPB trailer overall was approximately 2.5°C warmer (P = 0.01) compared to the MPB and AFD trailers while stationary at the farm. No differences (P > 0.10) in blood variables were found between trailers. The pHu value of the SM muscle was greater (P = 0.05) for pigs transported in the SPB trailer than in the AFD and MPB trailers. Given the few substantial effects of trailer models on animal welfare and meat quality, these three trailer models can be used indifferently for short-distance transportation in winter conditions in Canada.

In Pursuit of a Better Broiler: Welfare and Productivity of Slower-growing Broiler Breeders during Lay

Current commercial strains of broiler breeders display reproductive dysregulation when fed to satiety, but they can achieve optimal hatching egg production under feed restriction. However, chronic feed restriction in broiler breeders is a welfare concern due to physiological and behavioral signs of hunger, lack of satiety, and frustrated feeding motivation. The purpose of this study was to assess the welfare and productivity of slower-growing broiler breeders during lay. A total of 336 broiler breeders from 5 strains of slower-growing broiler breeders (3 female strains: 100 hens per strain, and 2 male strains: 12 and 24 roosters per strain) were kept in 12 identical pens throughout lay, 4 pens per combination of roosters and hens: A hens with Y roosters, B hens with Y roosters, and C hens with X roosters. According to guidelines, strain B and C hens and X roosters were slower growing strains and strain A hens and Y roosters were intermediate growing strains. Egg production was recorded daily, and settable eggs laid at 30, 40, and 50 wk of age were incubated to hatch. Growth rate, feed and water intake, and welfare indicators (feeding motivation, behavior, and physical assessment: feather coverage, foot and leg health, and keel bone status) were recorded during lay. Additionally, a subsample of 5 hens per pen was dissected for anatomical analyses. Laying rate started and peaked earlier in B hens than in A hens and remained above 70% in both strains, yielding high cumulative egg production (>165 eggs/hen) until 53 wk of age. Until 50 wk of age, fertility and hatched of fertile was high in slower growing broiler breeders, on average, above 95 and 80%, respectively. Compared to A hens, B and C hens had better feather coverage, lower feeding motivation, and lower daily water and feed intake. Results of this study suggest that slower growing broiler breeders show reduced signs of poor welfare and improved productivity during lay although susceptibility to obesity-related problems on laying rate may be strain-specific.

Genetic variation in LUMAN/CREB3 and association with stress and meat quality traits in Yorkshire pigs

LUMAN/CREB3 is a stress regulatory gene that affects the activity of the hypothalamic–pituitary–adrenal axis in mice and presents a promising avenue for exploring variable stress-responsiveness in pigs. Pigs with similar characteristics to LUMAN-deficient mice, including greater resilience to stress and receptivity to human handling, would be valuable in the pork industry from animal welfare and production efficiency perspectives. We previously identified eight genetic variations and five haplotypes throughout the LUMAN locus in Yorkshire pigs. In this study, we analysed associations between LUMAN variations with behavioural stress response during three tests (open field test, novel object test, and human approach test), physiological stress responsiveness (cortisol), and carcass/meat quality measurements from purebred Yorkshire pigs. Haplotypes A1 and A2 were associated with decreased activity levels in novel environments and greater plasma cortisol concentrations at slaughter. Haplotype A1 was associated with lower carcass scratch scores and meat with lower cooking losses and greater tenderness. Haplotypes B1 and B2 were associated with the opposite traits including increased activity levels in novel environments and characteristics for lower meat quality including greater cooking losses, lower marbling, and paler coloured meat. We conclude that DNA variations in the LUMAN locus could potentially be used as genetic markers for stress resistance and meat quality in pig breeding.

Welfare and performance of slower growing broiler breeders during rearing

Current commercial strains of broiler breeders can only achieve an optimal reproductive performance under feed restriction. However, chronic feed restriction in broiler breeders is a welfare concern because of physiological and behavioral signs of hunger, lack of satiety, and frustrated feeding motivation. The objective of this research was to assess the welfare and performance of slower growing broiler breeders during rearing. A total of 360 broiler breeder chicks from 3 female strains (100 chicks per strain) and 2 male strains (20 and 40 chicks per strain) were raised in four identical pens per strain. Strain B and C pullets and X cockerels were slower growing strains, and strain A pullets and Y cockerels were intermediate growing strains. Birds were weighed and scored individually for footpad lesions, hock burns and feather coverage. Data were analyzed using generalized linear mixed models with pen nested in the models and age as a repeated measure. Compared to B and C pullets, strain A pullets grew faster, had poorer body weight uniformity, and started feed restriction 2 wk earlier to control growth rate. Strain A pullets also had higher feeding rate at 3 and 5 wk, higher water intake at 4 and 5 wk, and higher prevalence of footpad lesions at 6 wk than the other pullet strains. Fault bars in wing feathers (an indicator of chronic stress) were more numerous in A pullets than in B and C pullets. Our results indicate that pullets showed little feather coverage loss during early rearing and had good body weight uniformity and low cumulative feed intake at the end of rearing. Slower growing broiler breeders may still require some degree of feed restriction to control growth rate, and strains with lower feed restriction exhibited lower signs of feeding frustration and high body weight uniformity.

Large-Scale Phenotyping of Livestock Welfare in Commercial Production Systems: A New Frontier in Animal Breeding

Genomic breeding programs have been paramount in improving the rates of genetic progress of productive efficiency traits in livestock. Such improvement has been accompanied by the intensification of production systems, use of a wider range of precision technologies in routine management practices, and high-throughput phenotyping. Simultaneously, a greater public awareness of animal welfare has influenced livestock producers to place more emphasis on welfare relative to production traits. Therefore, management practices and breeding technologies in livestock have been developed in recent years to enhance animal welfare. In particular, genomic selection can be used to improve livestock social behavior, resilience to disease and other stress factors, and ease habituation to production system changes. The main requirements for including novel behavioral and welfare traits in genomic breeding schemes are: (1) to identify traits that represent the biological mechanisms of the industry breeding goals; (2) the availability of individual phenotypic records measured on a large number of animals (ideally with genomic information); (3) the derived traits are heritable, biologically meaningful, repeatable, and (ideally) not highly correlated with other traits already included in the selection indexes; and (4) genomic information is available for a large number of individuals (or genetically close individuals) with phenotypic records. In this review, we (1) describe a potential route for development of novel welfare indicator traits (using ideal phenotypes) for both genetic and genomic selection schemes; (2) summarize key indicator variables of livestock behavior and welfare, including a detailed assessment of thermal stress in livestock; (3) describe the primary statistical and bioinformatic methods available for large-scale data analyses of animal welfare; and (4) identify major advancements, challenges, and opportunities to generate high-throughput and large-scale datasets to enable genetic and genomic selection for improved welfare in livestock. A wide variety of novel welfare indicator traits can be derived from information captured by modern technology such as sensors, automatic feeding systems, milking robots, activity monitors, video cameras, and indirect biomarkers at the cellular and physiological levels. The development of novel traits coupled with genomic selection schemes for improved welfare in livestock can be feasible and optimized based on recently developed (or developing) technologies. Efficient implementation of genetic and genomic selection for improved animal welfare also requires the integration of a multitude of scientific fields such as cell and molecular biology, neuroscience, immunology, stress physiology, computer science, engineering, quantitative genomics, and bioinformatics.

The effect of alternative feeding strategies for broiler breeder pullets: 1. Welfare and performance during rearing

Broiler breeders have impaired reproductive performance when fed to satiety but they can achieve an optimal hatching egg production under feed restriction. Feed restriction is a welfare concern due to signs of hunger, lack of satiety, and frustrated feeding motivation. The objective of this research was to examine the effect of a rationed alternative diet and non-daily feeding schedules on the performance and welfare of broiler breeder pullets reared under simulated commercial conditions. At 3 wk of age, 1,680 Ross 308 pullets were allocated to 24 pens fed with 1 of 4 treatments: 1) daily control diet (control); 2) daily alternative diet (40% soybean hulls and 1 to 5% calcium propionate); 3) 4/3 control diet (4 on-feed days per week; 3 non-consecutive off-feed days per week); and 4) graduated control diet (feeding frequency varied with age). Body weight and body weight uniformity were recorded at 3, 5, 7, 11, 17, and 21 wk of age. Pullets were scored for feather coverage, foot lesions, and hock burns biweekly. Physiological indicators (plasma glucose, corticosterone, hematology, and feather traits) and feeding motivation were also determined throughout rearing during on- and off-feed days. Data were analyzed using a linear mixed regression model, with pen nested in the model and age as a repeated measure. Compared to control, pullets under the 3 alternative feeding strategies had a lower feeding motivation during early rearing (P = 0.03), better feather coverage throughout rearing (P = 0.001), fewer feather fault bars (P = 0.006), and a delayed increase in the basophil to lymphocyte ratio (P = 0.001). These results indicate that the 3 alternative feeding strategies (the alternative, the graduated, and the 4/3 schedule) may decrease feeding motivation and alleviate stress compared to the control, suggesting an overall improvement in broiler breeder welfare without negative consequences on their performance.

The effect of alternative feeding strategies for broiler breeder pullets: 2. Welfare and performance during lay

Feeding broiler breeders to satiety has negative consequences on their health and reproduction. Alternative feeding strategies during rearing can improve welfare, although their implications during lay are not well understood. The objective was to examine the effect of rearing feeding treatments on the reproductive performance and feeding behavior of broiler breeders under simulated commercial conditions. At 3 wk of age, 1,680 Ross 308 pullets were allocated to 24 pens under 1 of 4 isocaloric treatments: 1) daily control diet; 2) daily alternative diet (40% soybean hulls and 1 to 5% calcium propionate); 3) 4/3 control diet (4 on-feed days, 3 non-consecutive off-feed days per week); and 4) graduated control diet. Feeding frequency of the graduated treatment varied with age and finished on a daily basis. At 23 wk of age, group sizes were adjusted to 40 hens, and 5 mature Yield Plus Males roosters were introduced to each pen. Pens were under the same daily feeding management and same diet during lay. The performance of broiler breeders (growth rate, body weight uniformity, and reproductive performance) was determined until 64 wk of age. At the end of lay, feeding motivation was examined with a feed intake test and a compensatory feeding test. Data were analyzed using linear mixed regression models, with pen nested in the models and age as a repeated measure. The laying rate of hens reared on the graduated treatment decreased slower compared to control hens, resulting in a higher cumulative egg production (178.2 ± 3.8 eggs/hen) than control hens (165.2 ± 3.8 eggs/hen, P < 0.01) by 64 wk of age. Hens reared on non-daily feeding treatments laid lighter eggs with relatively heavier yolks and had higher feed intake at the end of lay than hens fed daily during rearing (P = 0.02). In conclusion, rearing feeding treatments impacted the growth rate and body weight uniformity during lay, feeding motivation at the end of lay, and the laying rate and hatchability depending on hens' age.

The development of fault bars in domestic chickens (Gallus gallus domesticus) increases with acute stressors and individual propensity: implications for animal welfare

Negative experiences during feather growth can result in fault bar formation. Fault bars are malformations perpendicular to the rachis of the feather caused by stressful experiences during feather growth. However, there are little data on the causal effect of psychological stress on the formation of fault bars in chickens. The objective of this study was to examine the effect of acute stress in domestic chickens (Gallus gallus domesticus) on fault bar formation to validate this measure as a welfare indicator. Thirty broiler breeder pullets were housed in six cages at 21 days of age. Three cages were exposed to an acute stress protocol while the other three were the unstressed control. Feathers were marked as close as possible to the growing follicle at 21 (wing feathers) and 60 (all feathers) days of age. Acute stress came in the form of three procedures (unpredictable feed delivery, induction of tonic immobility, and crowding) repeated twice, 3–8 days apart and randomly, from 28 to 60 days of age. Wing, tail, and cover feathers were removed and measured at 60 days of age for weight, length, and number of fault bars. Exposure to acute, unpredictable stress increased the number of fault bars in wing feathers of chicks with a high number of initial fault bars. Feather growth decreased for the stressed group compared to the control. These results suggest that feather traits, including fault bars and feather growth, can be used as indicators of negative welfare in chickens.

Conditioned place avoidance using encapsulated calcium propionate as an appetite suppressant for broiler breeders

Broiler breeders, the parent stock of meat chickens, are feed-restricted throughout the production cycle to avoid obesity-related problems in their health and reproductive performance. Broiler breeders often show signs of chronic hunger, lack of satiety and feeding frustration, and the development of alternative feeding strategies has investigated the inclusion of calcium propionate (CaP) as an appetite suppressant. The mechanisms involved in the reduction of voluntary feed intake are unknown, but are thought to be due to low palatability, gastrointestinal discomfort, or both. The objective of this experiment was to examine the effect of CaP as an appetite suppressant on the experience of a negative affective state, using a conditioned place preference test. Twenty four broiler breeders were trained to associate the consumption of CaP or a placebo pill with a red or blue place, depending on inherent colour preference. Pullets consumed two pills followed by 20 g feed allotment. The CaP pill contained 160 mg of CaP and the placebo pill had 160 mg of feed. Conditioning lasted for 90 min/pullet/day over 8 consecutive days at 7 and 9 weeks of age, and pullets' choice was tested in a T-maze twice on two consecutive days at both 8 and 10 weeks of age. Data were analysed using a linear mixed regression model, with pen nested in the model and age as a repeated measure. Pullets were less likely to choose the place conditioned with the consumption of CaP (P<0.05) and the preference of the placebo linearly increased with training sessions (P<0.05). These results suggest that calcium propionate as an appetite suppressant can induce a negative affective state, reducing feed intake in broiler breeders fed CaP diets by causing an avoidance response rather than satiety.

Utilization of soy hulls, oat hulls, and flax meal fiber in adult broiler breeder hens

A total of 72, 65-week-old broiler breeder hens (Ross 308, BW 4,190 ± 45 g) was placed in individual cages to investigate utilization of fiber in soy hulls (SH), oat hulls (OH), and flax meal (FM). Birds were adapted to cages for 10 d prior to allocation (n = 18) to broiler breeder ration (control) or control mixed with either of the 3 fiber sources (wt/wt) added to supply equal amounts of neutral detergent fiber (NDF) ∼21% and TiO2. The daily feed allocation was based on 4% BW. Feed intake (FI) was monitored daily, and grab excreta samples were taken on d 16 and 17. On d 18, all birds were weighed and killed 2 h post feeding to measure ceca digesta pH and short chain fatty acids (SCFA). Relative to the control birds, birds receiving fiber lost (P < 0.05) BW due to decreased (P < 0.05) FI. The BW changes were respectively +80, -174, -133, and -585 g/bird for control, SH, OH, and FM, and corresponding FI was 1,062, 918, 885, and 590 g/bird. Birds fed FM retained higher (P < 0.05) NDF than birds fed either SH or OH. The ceca digesta pH was lower (P < 0.05) in birds receiving added fiber relative to control. However, ceca digesta pH of FM fed birds was lower (P < 0.05) than in birds fed either SH or OH, which were in turn similar (P > 0.05). Birds fed FM had higher (P < 0.05) concentration of butyric acid than birds fed the control diets, while birds fed SH and OH had intermediate butyric acid concentration. Acetic acid and total SCFA concentrations were higher (P < 0.05) in birds fed OH diet than in birds fed control but was similar (P > 0.05) to that in birds fed either SH or FM. In conclusion, short term feeding of fibrous feed ingredients reduced BW linked to reduced FI. Fiber sources exhibited differences in utilization reflective of chemical characteristics.

[The cost of cerebrovascular accident]

INTRODUCTION AND AIM

One out of three persons will die of cerebrovascular accident (CVA), another one will be disabled, and the third one will recover. This research has been taken to estimate the costs of CVA in the Basque Country.

MATERIALS AND METHODS

The cost of illness is studied from a societal perspective. It is based on the prevalence of the disease. Population costs has been estimated from the use of resources of a randomized sample of patients admitted to hospital with stroke during the year 2000, and followed for 12 months. Transitions costs (those that happen just once) and state costs (those remaining in patients lifetime) have been studied separately.

RESULTS

The prevalence of CVA was 1.780 x 10(5). Average transition cost per patient was 4,762 euros and average state cost for patient/year was 10,506 euros. The estimated cost for the Basque Country is 120,249,986 euros in the year 2000. Transition costs were 16,460,729 euros and state costs 103,789,257 euros in the same year. State costs were due to disability.

CONCLUSIONS

The analysis of the costs of CVA from a societal perspective gets us to the heart of illness causing disability, the social costs of CVA are 74.3% of the total cost.

[Hospital care of cerebrovascular accident and the state of patients 12 months after]

OBJECTIVES

Cerebrovascular accident should be of key importance due to its magnitude in terms of mortality and disability. In this study we describe hospital care of patients and follow them one year after. The aims is to uncover areas of improvement in the care of patients.

PATIENTS AND METHODS

Observational study of a randomized sample of 535 patient with a diagnosis of cerebrovascular disease, during de acute phase and 12 months after, using clinical records and telephone interview.

RESULTS

Thirty five percent of patients arrived within 6 hours of the occurrence of the event. Thirty six percent had a CAT/MNR within 6 hours. Mortality at hospital was 13.8% increasing up to 26% at 12 months. At discharge 49% had a neurological deficiency. At 12 months 35.8% of the survivors interviewed showed a Barthel Index of less than 95 points.

CONCLUSIONS

Organizational measures that guarantee a quick and systematic assessment of brain lesions, early diagnosis and active therapeutic offer, have to be implemented. In the sample studied, only 3% of the patient were candidates to thrombolytic therapy. Rehabilitation can and should play a more relevant role in the prevention of sequelae.

[Population-based epidemiology of colorectal cancer: causality review]

The estimated number of new cases of colorectal cancer per year in Spain (no. 19,166) is higher than other tumour locations. 1.56 times more cases of colon cancer are registered than of the rectum, and there are 1.44 times more cases in men than in women. Incidence and mortality are lower than the average for European countries; in historical series (1973-1999) an increase can be observed by age, period and birth cohorts between 1898 and 1932. On the contrary, in the USA a reduction of mortality can be observed from 1973 to 1999 (-20.8%) and of incidence from 1985 to 1999 (-7.4%). In Spain, the average duration of the disease in years is 4.29, lower than that of the European Community (4.57), and 72% of the figure for the most favourable country (5.93). Relative survival after five years in Spain is lower than in the USA (61.9% vs. 54%). Several dietary, environmental and lifestyle factors appear to be associated with colorectal cancer, but the risk or protection of these factors are of little weight and the results of studies are at times contradictory. The reduction of incidence in the USA indicates that intervention is possible to bring about a change of trend, predictably by means of secondary prevention.

[Can we help our patients to stop smoking?: the experience of the Smoking Cessation Program]

OBJECTIVE

To describe the process and results of the Smoking Cessation Program in order to answer this question: Does the lack of time and resources justify poor involvement of physicians in helping patients to stop smoking?

METHODS

Prospective series of cases that included all smokers (n = 1203) who for any reason attended seven general practices over a period of one year. The behaviour of smokers when the program was offered as well as the workload generated by the implementation of the process are described. Subjects who stopped smoking were those who did not smoke two years after enrolment in a sustained and validated form for least 12 months.

RESULTS

A total of 7.3% of all smokers quit (95% confidence interval [CI]: 5.9-8.9). Enrolment of subjects caused an increase in the consultation time of 23 seconds and decreased from a mean of 30 new smokers per month per practice during the first three months to 12 at the end of the first year. All received advise to stop smoking (mean increase of 3 min and 33 s) but only 17.5% accepted the therapeutic plan during the first year (95% CI: 15.4-19.9) that had a duration of 72:11 min and generated a mean of six programmed appointments a month in each practice. Twenty percent of subjects who participated in the therapeutic plan stopped smoking (95% CI: 14.8-26.1).

CONCLUSIONS

Identification and universal advice to smokers, together with treatment of those who are motivated to quit, achieved important success rates without increasing excessively ordinary work loads.

An evidence-based programme for smoking cessation: effectiveness in routine general practice

BACKGROUND

Smoking cessation clinical practice guidelines are based on randomised clinical trials reporting outcomes in persons who participate in these studies. However, many practitioners are sceptical about the effectiveness of these recommendations when applied to the general population in everyday routine consultation.

AIM

To evaluate the results of a comprehensive smoking cessation programme in routine primary care practice.

METHOD

All smokers consulting in 10 general practices during one year participated in a non-randomised controlled trial. The percentages of subjects in the intervention (n = 1203, seven practices) and control (n = 565, three practices) groups who reported sustained abstinence between six and 12 months follow-up and were validated biochemically were compared. The effect of the programme was adjusted to baseline differences in both groups by multiple logistic regression analyses.

RESULTS

The programme resulted in an increase of five percentage points (95% CI = 3.1%-6.8%) in the validated and sustained one-year abstinence probability, with 7.1% for all of the intervention practices (adjusted OR = 3.7, 95% CI = 2.4-5.7).

CONCLUSION

Programmes that combine advice to stop smoking to all smokers attending general practices with the offering of support, follow-up, and nicotine patches to those willing to stop are feasible and effective in routine practice, as primary care clinicians need only identify 20 smokers to get one additional success attributable to the programme.

Cell volume regulation in rat thymocytes

1. DIOA (dihydroindenyl-oxy-alkanoic acid), a potent inhibitor of the K(+)-Cl- co-transport system, fully blocked regulatory volume decrease (RVD) in swelled rat thymocytes, with an IC50 of 2.2 +/- 0.5 x 10(-5) mol l-1 (mean +/- S.D., n = 4). Conversely, RVD was resistant to quinine, quinidine, apamin, cetiedil, amiloride, bumetanide and DIDS (4,4'-diisothiocyanostilbene-2,2'-disulphonate). 2. DIOA-sensitive RVD followed mono-exponential kinetics, with t1/2 (half-lifetime) of 1-3 min and maximal capacity (Cmax) of about 55% of the initial cell swelling. Cmax and the initial rate of RVD (Vo) were both linear functions of the increase in cell volume. 3. RVD was: (i) slightly increased by replacing external Cl- by NO3-, (ii) reversed by replacing external Na+ by K+ (in the presence of external Cl-) and (iii) inhibited by cell K+ depletion. All these phenomena were blocked by DIOA (86 mumol l-1). 4. Increased membrane potassium permeability by valinomycin was unable to accelerate RVD or RVD reversal. 5. In the presence of DIOA, thymocytes responded like osmometers (the relative cell volume was a linear function of the reciprocal of the relative osmolality) in a large range of osmolalities. 6. The results strongly suggest that RVD in rat thymocytes is mediated by the K(+)-Cl- co-transport system.

The stilbene disulfonic acid DIDS stimulates the production of TNF-alpha in human lymphocytes

Exposure of human peripheral blood mononuclear cells (PBMC) to the stilbene derivative DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid) (60 microM and above) significantly increased the release of tumor necrosis factor-alpha (TNF-alpha), as determined by TNF-alpha activity in the incubation media. When the TNF-alpha message was analyzed in PBMC by a reverse transcription/polymerase chain reaction (RT/PCR)-based procedure, it was found that incubation with DIDS (60 microM) was followed by a time-dependent accumulation of TNF-alpha mRNA. Measurements of intracellular pH showed that the presence of increasing concentrations of DIDS resulted in a progressive intracellular alkalinization of PBMC. It is suggested that the known DIDS effect of inhibiting transmembrane anion exchange, i.e., chloride/bicarbonate exchange, might play a role in the stimulation of TNF-alpha production by PBMC exposed to DIDS.

Enhanced renal PGE2 in hypertensives with increased red cell Na(+)-Li+ countertransport

In this study, maximal velocities of Na(+)-Li+ countertransport were measured in red blood cells of 50 untreated essential hypertensives and 30 normotensive controls. In addition, urinary excretion of renal prostaglandins (PG) and plasma renin activity (PRA) was measured in each subject. Maximal velocity of Na(+)-Li+ countertransport was above the upper limit in controls of 525 mumol.l cell-1.h-1 in seven patients and was normal in the remaining patients. Patients with increased countertransport did not differ significantly from controls and from patients with normal countertransport with regard to urinary excretion of 6-keto-PGF1 alpha (the stable metabolite of prostacyclin) and thromboxane B2 (TxB2) (the stable metabolite of thromboxane A2). In contrast, mean values of PGE2 were significantly higher (P less than 0.01) in patients with increased countertransport (411 +/- 39 pg/min) compared with patients with normal countertransport (181 +/- 15 pg/min) and controls (146 +/- 13 pg/min). In addition, six patients with increased countertransport exhibited urinary levels of PGE2 higher than the upper limit in controls. Hypertensives with increased countertransport showed enhanced PRA when compared with the remaining patients (2.96 +/- 0.50 vs. 1.30 +/- 0.52 ng.ml-1.h-1, P less than 0.05) and with controls (1.86 +/- 0.08 ng.ml-1.h-1, P less than 0.05). Finally, the relationship between PGE2 and PRA was found to be significant in patients with increased countertransport (r = 0.776, P less than 0.05). These results indicate that renal synthesis of PGE2 is enhanced in essential hypertensives with increased Na(+)-Li+ countertransport activity and hyperreninemia.

Is the erythrocyte sodium-lithium countertransport a molecular marker of cardiac risk in hypertension?

Current research is being directed toward the identification of markers of cardiac risk in hypertension, according to demographic, clinical, genetic, challenge-response and laboratory predictors. Much interest has centered around cationic transporters as laboratory markers, not only because they might make good predictors of cardiac risk, but also because of their potential for explaining the pathophysiology of that disorder. To date, there is no cationic transporter that clearly discriminates between subjects with low and with high cardiac risk, although the sodium-lithium (Na(+)-Li+) countertransport in red blood cells has come the closest. High rates of Na(+)-Li+ countertransport have been found to be associated not just with essential hypertension but more specifically with subgroups of patients suffering from essential hypertension who have a higher frequency of severe hypertension and increased risk of cardiac disease. Here, we examine different lines of clinical evidence suggesting that increased Na(+)-Li+ countertransport activity may identify patients with essential hypertension who are at an increased risk of cardiac disease because they also present other cardiac risk factors, namely hyperlipidemia and/or left ventricular hypertrophy. In addition, the pathophysiological basis for the association of hypertension and the above cardiac risk factors with increased Na(+)-Li+ countertransport are discussed.

Is there increased cardiovascular risk in essential hypertensive patients with abnormal kinetics of red blood cell sodium-lithium countertransport?

Na+ transport kinetics were studied in red blood cells (RBCs) from 50 essential hypertensive patients and 30 normotensive controls. Seven hypertensive patients were characterized by the following: (1) a maximal rate of Na+-Li+ countertransport higher than an upper normal limit of 525 mumol.litre cells-1.h-1; (2) an apparent dissociation constant for internal Na+ higher than an upper normal limit of 20.4 mmol.litre cells (in only five of the seven hypertensives); (3) no other kinetic abnormality in Na+,K+ pump, Na+,K+ cotransport or passive Na+ permeability. Clinically, hypertensives with abnormal countertransport were characterized by high serum low-density lipoprotein (LDL) cholesterol levels and the presence of electrocardiographic left ventricular hypertrophy (LVH). Conversely, mean values of these two clinical parameters were normal in the remaining hypertensive patients, independently of the presence of other abnormalities in Na+,K+ pump, Na+,K+ cotransport or passive Na+ permeability. In conclusion, the presence of abnormal Na+-Li+ countertransport kinetics in erythrocytes may be associated with an enhanced cardiovascular risk in hypertension.

[Stimulation of the hydrolytic activity of Na+,K+-ATPase in the erythrocytes by arginine vasopressin]

The effects of arginine vasopressin (AVP) on Na+,K+-ATPase activity in human erythrocytes have been studied. AVP stimulates enzymatic activity with no effect on transport activity. Since the enzymatic reaction with AVP can proceed in the absence of ion transport, it may explain the discrepancies between the in vivo and in vitro effects observed with the hormone on Na+ processing by the kidney.