Chronic stress in dogs subjected to social and spatial restriction. I. Behavioral responses.

Six weeks of social and spatial restriction were used as a model to induce chronic stress in Beagles. Behavioral and physiological measurements were performed during a period of enriched spacious outdoor housing in groups (GH) and during a subsequent period of solitary housing in small indoor kennels (IH). Behavioral parameters that may indicate chronic stress in dogs are reported. During IH, the dogs showed significantly (comparison-wise error rate <0.05) lower postures than during GH. IH induced enduring increments in frequencies of autogrooming, paw lifting, and vocalizing, and was associated with incidents of coprophagy and repetitive behavior. So far, we interpret the behavioral changes as signs of chronic stress. Relatively low levels of walking, digging, intentions to change from one state of locomotion to another, and increments in circling are conceived as obvious adaptations to the specific features of the IH system. By challenging the dogs outside their home kennel we tested whether the dogs' coping abilities were affected by IH. Dogs that were challenged were introduced into a novel environment, given the opportunity to escape from their home kennel, restrained, walked down an unfamiliar corridor, presented a novel object, exposed to loud noise, given food, or confronted with a conspecific. During IH, challenged dogs exhibited higher postures, showed more tail wagging, nosing, circling, urinating, and defecating, and changed more often from one state of locomotion (or posture) to another than during GH. These behavioral changes were observed across the different types of challenges, with the exception of the noise administration test. In the presence of conspecifics, the socially and spatially restricted male dogs behaved more dominantly and aggressive than during the time that they were kept in groups. Such behavior manifested as increased performances of raised hairs, growling, paw laying, and standing over. Both sexes showed increases in paw lifting, body shaking, ambivalent postures, intentions to change from one state of locomotion to another, and trembling in any of the challenges, excluding the walking down the corridor test. In short, during a variety of challenges, socially and spatially restricted dogs exhibited a heightened state of aggression, excitement, and uncertainty. Behavioral differences between dogs that had experienced pleasant and bad weather conditions during GH, suggested that "pleasant-weather individuals" had experienced early stress during the control period, and, as a result, responded to the subsequent period of IH differently. Regardless of the housing conditions, challenged bitches showed stronger indications of acute stress than male dogs. Gender did not affect the chronic stress responses to social and spatial restriction. A low posture and increased auto-grooming, paw lifting, vocalizing, repetitive behavior, and coprophagy may indicate chronic stress in dogs, and as such, can help to identify poor welfare. When challenged, chronically stressed dogs may show increased excitement, aggression, and uncertainty, but the nonspecificity of such emotional behavior will complicate its practical use with regard to the assessment of stress.     

Hormonal responses to physical and cognitive stress in a school setting

Little is known about the influence of physical and cognitive stress on the concentration of steroid hormones (SHs) in a school setting. Forty high school students from the 9th grade were randomly assigned to two intervention groups: physical and cognitive stress. Saliva collection took place before (pre-test) and after (post-test) 12 min of high intensity exercise in a defined heart rate (HR) interval (70–85% HR _max; n = 19) and cognitive testing (Letter Digit Span and d2-test, n = 21), respectively. Saliva was analyzed for testosterone (T) and cortisol (C). Results indicated a significant increase of T and C due to a physical but not cognitive stressor. Thus, only the physical stressor was capable of activating the hypothalamic–pituitary–adrenal (HPA) and the hypothalamic–pituitary–gonadal (HPG) axis.     

Hormonal,immune, and oxidative stress responses to blood flow-restricted exercise

Introduction

Heavy-load free-flow resistance exercise (HL-FFRE) is a widely used training modality. Recently, low-load blood-flow restricted resistance exercise (LL-BFRRE) has gained attention in both athletic and clinical settings as an alternative when conventional HL-FFRE is contraindicated or not tolerated. LL-BFRRE has been shown to result in physiological adaptations in muscle and connective tissue that are comparable to those induced by HL-FFRE. The underlying mechanisms remain unclear; however, evidence suggests that LL-BFRRE involves elevated metabolic stress compared to conventional free-flow resistance exercise (FFRE).

Aim

The aim was to evaluate the initial (<10 min post-exercise), intermediate (10–20 min), and late (>30 min) hormonal, immune, and oxidative stress responses observed following acute sessions of LL-BFRRE compared to FFRE in healthy adults.

Methods

A systematic literature search of randomized and non-randomized studies was conducted in PubMed, Embase, Cochrane Central, CINAHL, and SPORTDiscus. The Cochrane Risk of Bias (RoB2, ROBINS-1) and TESTEX were used to evaluate risk of bias and study quality. Data extractions were based on mean change within groups.

Results

A total of 12525 hits were identified, of which 29 articles were included. LL-BFRRE demonstrated greater acute increases in growth hormone responses when compared to overall FFRE at intermediate (SMD 2.04; 95% CI 0.87, 3.22) and late (SMD 2.64; 95% CI 1.13, 4.16) post-exercise phases. LL-BFRRE also demonstrated greater increase in testosterone responses compared to late LL-FFRE.

Conclusion

These results indicate that LL-BFRRE can induce increased or similar hormone and immune responses compared to LL-FFRE and HL-FFRE along with attenuated oxidative stress responses compared to HL-FFRE.     

Hormonal contraception use alters stress responses and emotional memory

Emotionally arousing material is typically better remembered than neutral material. Since norepinephrine and cortisol interact to modulate emotional memory, sex-related influences on stress responses may be related to sex differences in emotional memory. Two groups of healthy women – one naturally cycling (NC women, n = 42) and one using hormonal contraceptives (HC women, n = 36) – viewed emotionally arousing and neutral images. Immediately after, they were assigned to Cold Pressor Stress (CPS) or a control procedure. One week later, participants received a surprise free recall test. Saliva samples were collected and later assayed for salivary alpha-amylase (biomarker for norepinephrine) and cortisol. Compared to NC women, HC women exhibited significantly blunted stress hormone responses to the images and CPS. Recall of emotional images differed between HC and NC women depending on noradrenergic and cortisol responses. These findings may have important implications for understanding the neurobiology of emotional memory disorders, especially those that disproportionately affect women.     

Sympathetic and parasympathetic responses to social stress across adolescence

Many transformations that occur in adolescence are related to emotion and emotion regulation, yet very little is known about the autonomic underpinnings of these changes. The aim of the study was to document age-related differences in autonomic responses to social stress and relations to emotion regulation. Ninety-nine female adolescents engaged in a paced breathing and a spontaneous speech task while electrocardiography measurements were taken. Spectral decomposition of the heart period data was used to create measures of sympathetic and parasympathetic activity. Results revealed a positive correlation between age and sympathetic activity and a negative correlation between age and parasympathetic activity. These findings contribute to a better understanding of the age-related norms of cardiac variability across adolescence.     

Gender, social support, and cardiovascular responses to stress

OBJECTIVE: Laboratory research indicates that the presence of a supportive other can reduce physiological responses to a stressor. Whether there are gender differences, either on the part of the provider or the recipient, in this social support effect is explored. Such differences might shed some light on the frequent epidemiological reports of gender differences in social support and health. METHODS: Male and female subjects gave an impromptu speech and received either standardized supportive or nonsupportive feedback from a male or female confederate. Blood pressure and heart rate were monitored continuously during baseline and speech periods. RESULTS: Speakers with a supportive female audience showed a systolic increase of 25 mm Hg over baseline. Those with a nonsupportive female audience increased 36 mm Hg. A supportive male audience led to increases of 32 mm Hg, and a nonsupportive male audience 28 mm Hg. There was no significant effect of gender of subject. CONCLUSIONS: Results indicate that social support provided by women reduced cardiovascular changes for both male and female speakers compared with presence of a nonsupportive female audience. Social support from men did not. These findings suggest a possible mechanism that might help explain the epidemiological literature on the relationship between gender, social support, and health. The findings are consistent with the notion that married men are healthier because they marry women. Women do not profit as much from marriage or suffer as much from separation, in terms of health outcomes, because the support they gain or lose is the less effective support of a man. These findings render more plausible the possibility that differences in social support might contribute to health differences, through the dampening of cardiovascular responses to stress.     

Hormonal responses to whole-body vibration in men

The aim of this study was to evaluate the acute responses of blood hormone concentrations and neuromuscular performance following whole-body vibration (WBV) treatment. Fourteen male subjects [mean (SD) age 25 (4.6) years] were exposed to vertical sinusoidal WBV, 10 times for 60 s, with 60 s rest between the vibration sets (a rest period lasting 6 min was allowed after 5 vibration sets). Neuromuscular performance tests consisting of counter-movement jumps and maximal dynamic leg presses on a slide machine, performed with an extra load of 160% of the subjects body mass, and with both legs were administered before and immediately after the WBV treatment. The average velocity, acceleration, average force, and power were calculated and the root mean square electromyogram (EMGrms) were recorded from the vastus lateralis and rectus femoris muscles simultaneously during the leg-press measurement. Blood samples were also collected, and plasma concentrations of testosterone (T), growth hormone (GH) and cortisol (C) were measured. The results showed a significant increase in the plasma concentration of T and GH, whereas C levels decreased. An increase in the mechanical power output of the leg extensor muscles was observed together with a reduction in EMGrms activity. Neuromuscular efficiency improved, as indicated by the decrease in the ratio between EMGrms and power. Jumping performance, which was measured using the counter-movement jump test, was also enhanced. Thus, it can be argued that the biological mechanism produced by vibration is similar to the effect produced by explosive power training (jumping and bouncing). The enhancement of explosive power could have been induced by an increase in the synchronisation activity of the motor units, and/or improved co-ordination of the synergistic muscles and increased inhibition of the antagonists. These results suggest that WBV treatment leads to acute responses of hormonal profile and neuromuscular performance. It is therefore likely that the effect of WBV treatment elicited a biological adaptation that is connected to a neural potentiation effect, similar to those reported to occur following resistance and explosive power training. In conclusion, it is suggested that WBV influences proprioceptive feedback mechanisms and specific neural components, leading to an improvement of neuromuscular performance. Moreover, since the hormonal responses, characterised by an increase in T and GH concentration and a decrease in C concentration, and the increase in neuromuscular effectiveness were simultaneous but independent, it is speculated that the two phenomena might have common underlying mechanisms. Accepted: 8 September 1999     

Female popliteal lymph node responses to H-Y antigen on male thymocytes in mice. II. H-2 restriction of secondary responses

C57BL/10 (abbreviation B10) female mice give a high primary popliteal lymph node (PLN) response to syngeneic male thymocytes. The PLN response to the H-Y antigen is suppressed if B10 females are primed by an intraperitoneal injection of syngeneic male cells. Suppression of the response can be induced by priming with not only syngeneic B10 male thymocytes but also allogeneic thymocytes which share the H-2D locus of the H-2b haplotype with the responder (Db restriction). On the other hand, B10.D2, B10.A, and HTO female mice, giving a low primary PLN response to H-Y, give high secondary PLN responses when primed intraperitoneally with syngeneic male thymocytes. A high secondary response can also be obtained by priming with allogeneic male thymocytes which share the K end loci (K, A beta, A alpha, E beta, and E alpha) of the H-2 complex with the responder. Apparently the male thymocytes used for priming must share class I (and possibly class II) H-2 loci with the female recipients to enable the recognition of the H-Y antigen and subsequent development of the genetically determined type (suppression or amplification) of the secondary PLN response.     

Chronic social stress in a changing dietary environment

The human population has slowly transformed from the "hunter-gatherer" period to the current environment of high energy consumption, minimal physical activity and a lifestyle that includes stress and anxiety. Modeling the current environment in the laboratory can help to elucidate mechanisms responsible for the development of obesity, diabetes and, ultimately, the metabolic syndrome. Using the visible burrow system (VBS) model of social stress we have begun to examine the short- and long-term consequences of chronic social stress on energy homeostasis. We demonstrated that social stress has significant effects on body weight and body composition such that subordinate rats progressively develop characteristics of obesity and have additionally determined that this occurs, in part, through changes in food intake amount and behavior. Changes in body weight and body composition are similar or greater when animals are maintained on a high fat diet. These data suggest that consumption of a high-fat diet during social stress in the VBS, while it does not appear to affect development of a social hierarchy, enhances the effect that chronic stress has on body composition and may be more representative of what happens in humans in modern society where the typical diet has progressively moved toward higher calorie, high-fat foods.     

Hormonal and behavioral responses to stress in lactating and non-lactating female common marmosets (Callithrix jacchus)

In several mammalian species, hypothalamic-pituitary-adrenal (HPA) and behavioral responses to stressors are down-regulated in lactating females, possibly preventing stress-induced disruptions of maternal care. Experimental elevations of HPA axis hormones have been found to inhibit maternal behavior in lactating common marmoset monkeys (Callithrix jacchus), raising the question of whether lactating female marmosets also have blunted endogenous responses to stress. Therefore, we compared HPA and behavioral responses to standardized stressors in reproductively experienced female common marmosets that were undergoing ovulatory cycles and that either were (N = 7) or were not lactating (N = 8). Each marmoset underwent (1) a restraint stressor during the early follicular phase of the ovarian cycle (approximately 5 weeks postpartum for lactating females) and (2) exposure to a simulated hawk predator during the early to mid-luteal phase (approximately 7 weeks postpartum for lactating females). Lactating females were tested in the presence of one of their infants. Blood samples were collected before, during, and immediately after each test for determination of plasma adrenocorticotropic hormone (ACTH) and cortisol concentrations. Both stressors caused significant elevations in plasma ACTH and cortisol levels, and significant decreases in cortisol:ACTH ratios; however, lactating and non-lactating females showed no significant differences in their endocrine or behavioral responses to either stressor, or in baseline ACTH or cortisol levels. These findings suggest that in contrast to several other mammalian species, lactating female marmosets maintain full behavioral and HPA responsiveness to stress, at least in the presence of their infants.     

Hormonal responses to fenfluramine in depressed and control subjects

To investigate central neurotransmitter function in depression, baseline levels of serum cortisol and prolactin and the responses of these hormones to the putative serotonin agonist fenfluramine (60 mg, oral) were examined in 27 depressed patients and 14 normal subjects. Baseline cortisol was significantly elevated (P less than 0.01) in depressed subjects, whilst baseline prolactin was significantly reduced (P = 0.01) after covarying for cortisol. Although there were no significant abnormalities in either the prolactin or the cortisol response to fenfluramine in the total depressed group, the peak increase in prolactin levels (delta PRL) was significantly reduced (P less than 0.05) in subjects with endogenous depression. Analysis of covariance demonstrated, however, that the reduced delta PRL was partially dependent upon the abnormal baseline prolactin and cortisol levels. These results indicate the necessity of accounting for these baseline effects when investigating hormonal responses to the putative serotonergic challenges. The abnormal baseline findings are consistent with increased central noradrenergic activity in depression.     

Neurochemical, endocrine and immunological responses to stress in young and old Fischer 344 male rats

Two experiments were performed. In the first, a 20 min conditioned emotional response (CER) paradigm was used to compare the neurochemical, endocrine and immunological responses to stress of 7- and 22-month-old Fischer 344 (F344) male rats. In the second, corticosterone levels 20 min following ether stress, and regional brain type I and II corticosterone receptor densities were examined using 7- and 17.5-month-old F344 male rats. Dopamine (DA) metabolism in old nonstressed rats was significantly reduced in the medial frontal cortex, neostriatum, nucleus accumbens and hypothalamus, but not in the amygdala. The CER procedure, nevertheless, increased medial frontal cortical, nucleus accumbens and amygdaloid DA turnover in both the young and old rats. The young and old nonstressed rats did not evidence differences in norepinephrine (NE) and serotonin (5-HT) concentrations. However, stress resulted in a decrease in medial frontal cortical 5-hydroxyindoleacetic acid (5-HIAA) and hypothalamic 5-HT levels in old but not in young animals. These observations suggest age-related differences in the response of central NE and 5-HT systems to stress. Ether and the CER procedure led to exaggerated corticosterone responses in the old rats (17.5 and 22 month, respectively). Hippocampal type I but not type II corticosterone receptors were decreased by 47% in the 17.5-month-old rats. Thus, age-related changes in hippocampal corticosterone receptor types do not occur in unison, and the exacerbated corticosterone response to stress precedes the reported down-regulation of hippocampal type II corticosterone receptors in aged rats. Age-related changes were not observed in the concentrations of corticosterone receptors in other brain regions, or in the prolactin response to stress. The old rats, however, evidenced a reduction in the availability of the renin substrate, angiotensinogen, and in stress-induced renin secretion. Immune function was impaired in the old nonstressed rats, and further compromised by exposure to the CER procedure. In comparison to the young control rats, the old nonstressed rats showed an increased percentage of splenic large granular lymphocytes, reduced splenic natural killer cytotoxicity, and impaired Con-A-stimulated splenic T lymphocyte proliferation. Reductions in T splenic cell proliferation and natural killer cytotoxicity were observed in the young rats subjected to the CER paradigm, but not to the same extent as in the old rats. These observations indicate that aging male F344 rats evidence major alterations in basal central monoamine, endocrine and immune functions, and an increased sensitivity of these systems to stress.     

Chronic stress undermines the compensatory sleep efficiency increase in response to sleep restriction in adolescents

To investigate the effects of real‐life stress on the sleep of adolescents, we performed a repeated‐measures study on actigraphic sleep estimates and subjective measures during one regular school week, two stressful examination weeks and a week's holiday. Twenty‐four adolescents aged 17.63 ± 0.10 years (mean ± standard error of the mean) wore actigraphs and completed diaries on subjective stress, fatigue, sleep quality, number of examinations and consumption of caffeine and alcohol for 4 weeks during their final year of secondary school. The resulting almost 500 assessments were analysed using mixed‐effect models to estimate the effects of mere school attendance and additional examination stress on sleep estimates and subjective ratings. Total sleep time decreased from 7:38 h ± 12 min during holidays to 6:40 h ± 12 min during a regular school week. This 13% decrease elicited a partial compensation, as indicated by a 3% increase in sleep efficiency and a 6% decrease in the duration of nocturnal awakenings. During examination weeks total sleep time decreased to 6:23 h ± 8 min, but it was now accompanied by a decrease in sleep efficiency and subjective sleep quality and an increase in wake bout duration. In conclusion, school examination stress affects the sleep of adolescents. The compensatory mechanism of more consolidated sleep, as elicited by the sleep restriction associated with mere school attendance, collapsed during 2 weeks of sustained examination stress.     

Hormonal responses to high- and moderate-intensity strength exercise

The hormonal responses of nine male, strength athletes to strength exercise were examined. The athletes performed one moderate- and one high-intensity strength exercise workout. In the high-intensity workout, the load was 100% of each subject's three-repetition maximum (3-RM) for squats and front squats, and 100% of each subject's six-repetition maximum (6-RM) for leg extensions. In the moderate-intensity workout, the load was 70% of the high-intensity protocol. Rest periods between sets were 4–6 min for both workouts. Blood samples were taken before, 30 min into, and every 15 min for the 1st h after exercise, and then 3, 7, 11, 22 and 33 h after exercise, thus allowing examination of both the acute and prolonged hormonal responses. Blood samples were analyzed for testosterone, luteinizing hormone (LH), follicle stimulating hormone (FSH), cortisol, adrenocorticotrophic hormone (ACTH), growth hormone (GH), insulin-like growth factor (IGF-1), insulin, sex hormone binding globulin, creatine kinase, total protein, glucose and lactate. The acute responses of testosterone and cortisol were greater during the high-intensity protocol as compared to the moderate-intensity protocol. The cortisol response was associated with an increase in ACTH concentration. LH and FSH showed no response to either protocol. Acute GH responses were not different between protocols. There were great inter-individual differences in acute GH responses to both protocols. There were no significant differences between protocols with regard to prolonged responses for any hormone. In both trials, IGF-1 concentrations were significantly lower at 0800 hours the morning after exercise as compared to concentrations found at 0800 hours the morning before exercise. The mechanisms responsible for reducing IGF-1 concentration in these trials are unclear, and it is not known if this reduction observed 22 hours after exercise is of physiological significance. Accepted: 13 December 1999     

Hormonal responses to three training protocols in rowing

The aim of this study was to examine the acute responses of serum growth hormone, testosterone, and cortisol to three training protocols in rowing. Six young rowers, members of the national team, carried out three frequently used protocols in rowing, i.e., an endurance, a moderate interval, and a resistance protocol, on separate days in a counterbalanced design. Blood samples were collected before, immediately after, and 4 h after exercise for the determination of growth hormone, testosterone, cortisol, and creatine kinase. All three protocols caused marked increases in growth hormone, the most spectacular being that immediately after the endurance protocol. The change in testosterone concentration immediately after the endurance protocol was significantly higher than the changes after the other two protocols. Cortisol concentration was significantly higher immediately after the endurance protocol than after the other two protocols, but remained relatively low in all cases, suggesting that these protocols did not considerably promote catabolism in muscle tissue. Based on these data, endurance training caused greater responses of the three hormones studied compared to interval or resistance training. In fact, resistance training (at intensities above 85% of 1RM) did not cause any significant changes in the three hormones. We therefore propose that evaluation of training programmes designed for elite athletes should include measurements of hormonal changes in order to ascertain that the programmes do cause the expected adaptations.     

The effects of social stress and cortisol responses on the preconscious selective attention to social threat

The purpose of the present study was to investigate the effects of social stress and stress-induced cortisol on the preconscious selective attention to social threat. Twenty healthy participants were administered a masked emotional Stroop task (comparing color-naming latencies for angry, neutral and happy faces) in conditions of rest and social stress. Stress was induced by means of the Trier social stress test. Based on the stress-induced increase in cortisol levels, participants were allocated post hoc (median-split) to a high and low responders group. In contrast to low responders, high responders showed a negative or avoidant attentional bias to threat (i.e. shorter latencies for angry than neutral faces) in the rest condition. Most importantly, although low responders became avoidant, the high responders became vigilant to the angry faces after stress induction. There were no such effects for happy faces. Our findings are in line with previous studies in both animals and humans, that associate high glucocorticoid stress-responsiveness with diminished avoidance and prolonged freezing reactions during stress.     

Anatomical and immunological responses of rabbit gallbladders to bacterial infections.

To study the sequential morphological and immunological response of the rabbit gallbladder to bacterial infection and to compare the inflammatory responses with different pathogens, gallbladders were infected with Streptococcus faecalis and two strains of Escherichia coli, one of which produced enterotoxin. Gallbladder infection was produced either by intravenously injecting bacteria into rabbits with a small liver infarct or by injecting bacteria directly into the gallbladder of normal rabbits. The percentage of gallbladders infected intravenously with a nonenterotoxigenic E. coli strain was 86% at 1 week, 70% at 3 weeks, and 15% at 6 weeks. Epithelial necrosis and leukocyte infiltration were prominent 1 week after infection. At 3 and 6 weeks after infection, there was crypt distortion and increased mucus secretion in the epithelium as shown by periodic acid-Schiff staining. The lamina propria was infiltrated with mononuclear cells, many of which were plasma cells. Myofibroblasts (contractile fibroblasts) were also identified on transmission microscopy, In addition to these changes, toxigenic E. coli produced subepithelial capillary dilation in the villus core. Morphological changes (excluding toxin-associated changes) were related to the duration of infection rather than to the specific species of infecting bacteria. Infected gallbladders studied by immunofluorescence had a greater than 50-fold increase in plasma cells compared with control cells. In addition, the number increased with the duration of infection. Immunoglobulin A cells were the major cell type in gallbladders infected by intravesical injection, whereas immunoglobulin G cells predominated in gallbladders infected intravenously. The gallbladder appears to mount a local immune response to bacterial infection.     

Self-focus and social evaluative threat increase salivary cortisol responses to acute stress in men

This experiment tested the hypothesis that self-focused attention might increase cortisol release. Social self-preservation theory suggests that social evaluation and associated feelings of shame are associated with cortisol reactivity, whereas one implication of objective self-awareness theory is that self-critical awareness and associated feelings of anxiety might be associated with increases in cortisol. 120 participants completed a public speech task either in front of an evaluative panel (social threat), in a non-evaluative setting while watching themselves in real-time on a television (self-focus), or in the mere presence of a non-evaluative person (control). Cortisol increased comparably among men in the social threat and self-focus conditions, but not among men in the control condition. There were no effects for women. Shame was correlated with increased cortisol in the social threat condition, whereas anxiety was correlated with increased cortisol in the self-focus condition. One broad implication of this work is that negative evaluation may increase cortisol regardless of whether this source comes from oneself or others.     

Angiotensin II in the renal excretory response to behavioral stress in conscious dogs

The effects of inhibition of the renin-angiotensin system on the decreased renal excretion of sodium and water resulting from behavioral stress (shock avoidance) were examined in conscious saline-infused (4-5 ml/min) dogs. During saline infusion alone in six dogs, avoidance decreased sodium excretion (64% from 329 mueq/min) and urine flow (63% from 1.9 ml/min). During converting enzyme inhibition with captopril in the same dogs, the decreases in sodium excretion (35% from 464 mueq/min) and urine flow (35% from 2.6 ml/min) during avoidance were attenuated. Similarly, in six other dogs, avoidance decreased sodium excretion (41% from 361 mueq/min) and urine flow (43% from 2.1 ml/min) with saline infusion alone. During angiotension II (ANG II) receptor antagonism with saralasin, decreases in sodium excretion (29% from 417 mueq/min) and urine flow (27% from 2.2 ml/min) were attenuated. These mean changes in excretion during inhibition of the renin-angiotensin system were significantly (P less than 0.05) less than during saline alone. Whereas decreases in fractional sodium and water excretion were attenuated by renin-angiotensin inhibition, decreases in glomerular filtration rate and effective renal blood flow and increases in mean arterial pressure were not affected. These results indicate that ANG II contributes to the renal excretory response to avoidance.     

Spousal negative responses to cancer patients: the role of social restriction, spouse mood, and relationship satisfaction.

This cross-sectional study examined perceptions of spousal negative behaviors in 219 cancer patients. A mediational model was proposed to explain why a spouse might respond negatively to an ill partner because of greater restriction on activities as functional impairment increases. A moderating effect of the spouse's marital satisfaction assessed 3 months before other study measures was also proposed. Results provided support for the proposed model. The relationship between increasing patient functional impairment and spousal negative behaviors was medicated by greater restriction in spouse activities, as well as spousal negative mood. A marginally significant moderating effect for marital satisfaction was found. Although these results must be replicated with a prospective study, the findings begin to shed light on why spouses might respond in negative ways to an ill partner.