Amino acid efficiencies of utilization vary by different mechanisms in response to energy and protein supplies in dairy cows: Study at mammary-gland and whole-body levels.

Variations of mammary gland (MG) metabolism were studied in dairy cows in response to diets containing 2 levels of net energy of lactation [NEL; 25.0 and 32.5 Mcal/d for low (LE) and high energy (HE), respectively], combined with 2 levels of metabolizable protein [MP, 1,266 and 2,254 g/d of protein digestible in the intestine for low (LP) and high protein (HP), respectively] in a 2 × 2 factorial arrangement. Four cows received 4 diets (LELP, HELP, LEHP, and HEHP) in a 4 × 4 Latin square design with 2-wk experimental periods. Milk production and feed intake were measured on the last 5 d of each period, whereas MG net uptake of AA was determined on d 13. Efficiencies were estimated as the sum of measured milk true protein yield (MPY) and of estimations of metabolic fecal and scurf proteins multiplied by their respective AA profile and divided by the estimated AA supply minus the AA endogenous urinary loss. The increased MPY in the HE compared with the LE diets (higher by 123 g/d) was accompanied by increased mammary plasma flow and MG uptake of the nonessential AA (NEAA) and the essential AA (EAA), except for branched-chain AA. In contrast, the increase in MPY (higher by 104 g/d) observed in the HP compared with the LP diets was linked to increased MG uptake of EAA without a change in mammary plasma flow and a decreased NEAA uptake. Because MG uptake of total AA-N was almost equal to cows' milk output on a nitrogen basis, these different mechanisms involve a large MG flexibility, with variable synthesis of NEAA. In addition, MP efficiency did not increase only through increased MPY in the HE compared with the LE diets but also through metabolic fecal protein, estimated to increase (by 65 g/d) with dry matter intake. The MPY increased in the HP compared with the LP diets, but the increase was smaller than the calculated increase (greater by 993 g/d) in MP supply. The highest MG clearance rates of individual EAA could suggest that Met, His, and Lys were limiting in LP, and Met was the most limiting AA in HP. Interestingly, a similar hypothesis could be stated by analyzing estimated AA efficiencies. The highest efficiencies among EAA, observed for His in HELP and for Met with the other diets, could indicate that they were the most limiting AA in these respective diets, whereas other EAA (including Lys) efficiencies varied with MP efficiency. The MG metabolic flexibility with regard to individual AA utilization partially contributes to the anabolic fate of AA through MPY; however, other export proteins also contribute to variations in MP and AA efficiencies.

Inhibiting prolactin by cabergoline accelerates mammary gland remodeling during the early dry period in dairy cows.

The inhibition of prolactin release using cabergoline, a dopamine agonist, is an effective strategy to accelerate the changes in mammary secretion composition after drying-off. The objective of this study was to determine how cabergoline may affect mammary tissue remodeling during early involution. Holstein dairy cows were treated with either a single i.m. administration of 5.6 mg of cabergoline (Velactis, Ceva Santé Animale, Libourne, France, n = 7) or placebo (n = 7) at the time of drying-off. Mammary biopsy samples were collected 1 wk before drying-off (d -6), after 30 h of milk accumulation (d 1), and again 8 d following drying-off (d 8) to determine changes in gene expression, lactoferrin content, and cell turnover. Blood and mammary secretion samples were collected at d -6 and again at d 1, 2, 3, 4, 8, and 14 following the abrupt cessation of lactation to evaluate indicators of blood-milk barrier integrity and other markers of mammary tissue remodeling. Cabergoline induced less SLC2A1, BAX, CAPN2, and IGFBP5 mRNA expression. In contrast, cabergoline did not modify changes in cell proliferation and apoptosis. Following the cessation of lactation, changes in mammary secretion composition (Na+ and K+) and blood lactose concentrations were indicative of a loss in the blood-milk barrier function in both treatment groups. Cabergoline treatment affected only Na+ and K+ concentrations at d 1, suggesting a moderate increase in tight junction permeability. The increase in the activity of MMP9 and in mammary epithelial cell concentration in mammary secretions was greater in cabergoline-treated cows than in control cows, suggesting more mammary tissue remodeling. The increase in lactoferrin immunostaining in the mammary tissue occurred earlier for cabergoline-treated cows than for control cows, and was essentially localized in the stroma. Changes in some key markers of mammary involution suggest that cabergoline accelerates mammary gland remodeling. Thus, a single injection of cabergoline after the last milking would facilitate drying-off by enhancing mammary gland involution.

Dietary cation-anion difference and day length have an effect on milk calcium content and bone accretion of dairy cows.

Milk and dairy products are an important source of Ca for humans. Recent studies have shown fluctuations in cow milk Ca content during the year in France, with high values in winter and with corn silage diets, and a decrease during May and June and with grass diets. The aim of this study was to identify the reasons for this seasonal decrease in milk Ca content by testing the effect of 2 levels of dietary cation-anion differences (DCAD; 0 mEq/kg of dry matter for DCAD 0 and 400 mEq/kg for DCAD 400) and 2 day lengths (8 h of light/d for short days: SD; and 16 h/d for long days: LD) on the Ca balances of dairy cows. The DCAD treatments were designed to mimic diets based either on corn silage or on herbage. The cows were only illuminated by solarium lights providing UVA and UVB. The trial was conducted according to 2 simultaneous replicates of a 4×4 Latin square design using 8 dairy cows averaging 103±44 d in milk with 4 periods of 14 d. Data were analyzed by ANOVA with a model including treatment, cow, and period effects. No significant interaction was found between day length and DCAD treatments. With DCAD 400 compared with DCAD 0, blood pH increased and plasma ionized Ca content decreased, whereas the plasma total Ca content did not differ between treatments. Milk Ca content, however, increased with DCAD 400 compared with DCAD 0, in relation to a decrease in the amount of Ca excreted in urine. The DCAD had no significant effect on protein and casein contents and DCAD 400 tended to decrease milk yield. This illustrates that the udder did not decrease Ca uptake from the blood at high DCAD even though DCAD 400 decreased the mammary availability of Ca by decreasing the proportion of blood ionized Ca. Milk Ca and casein contents were significantly lower with LD compared with SD, whereas day length had no effect on milk yield after 14 d of treatment. Bone accretion of cows increased when the Ca content of milk increased (i.e., with DCAD 400 compared with DCAD 0 and with SD compared with LD). This work suggests that long and sunny days could explain part of the seasonal decrease in milk Ca content in summer and refutes the hypothesis that low milk Ca contents at grazing could be due to the high DCAD of herbage.

Cabergoline inhibits prolactin secretion and accelerates involution in dairy cows after dry-off.

Dairy cattle require a dry period between successive lactations to ensure optimal milk production. Because prolactin (PRL) is necessary for the initiation and maintenance of milk production, strategies that can inhibit PRL secretion might hasten the involution process. The objective of this study was to determine the effect of the PRL release inhibitor cabergoline on markers of mammary gland involution during the early dry period. To assess the effect of cabergoline treatment on mammary gland involution, 14 Holstein dairy cows in late lactation were treated with either a single i.m. administration of 5.6mg of cabergoline (Velactis, Ceva Santé Animale, Libourne, France, n=7) or placebo (n=7) at the time of dry-off. Blood samples and mammary secretion samples were collected 6d before dry-off and again 1, 2, 3, 4, 8, and 14d following the abrupt cessation of lactation. Blood samples were used to determine plasma PRL concentrations. Mammary secretion samples were used to determine somatic cell count, milk fat, lactose, true protein content, and concentrations of α-lactalbumin, lactoferrin, and citrate. Following the cessation of lactation, changes in mammary secretion composition indicated diminished milk synthesis, including reduced concentrations of α-lactalbumin, citrate, and lactose. In contrast, milk somatic cell count, percent total protein, percent fat content, and lactoferrin concentrations significantly increased as involution progressed. Cabergoline treatment decreased the plasma PRL concentrations during the first week of dry-off, compared with the control treatment. No significant differences in citrate, α-lactalbumin, or protein content were observed between treatment groups. The most dramatic changes in secretion composition as a consequence of cabergoline treatment occurred during the first week of the dry period, when lactose concentrations and the citrate:lactoferrin molar ratio were lower and lactoferrin concentrations higher than in the control cows. Cabergoline treatment also tended to increase fat content and somatic cell count more rapidly following dry-off compared with the control group. These changes in mammary secretion composition following the abrupt cessation of lactation indicate that cabergoline treatment facilitated dry-off and effectively accelerated mammary gland involution.

Changes in mammary metabolism in response to the provision of an ideal amino acid profile at 2 levels of metabolizable protein supply in dairy cows: Consequences on efficiency.

The aim of this study was to compare the modifications in mammary gland metabolism by supplying an ideal versus an imbalanced essential AA (EAA) profile at low and high metabolizable protein (or PDIE, its equivalent in the INRA feeding system). Four lactating, multiparous Holstein cows received 4 treatments composed of 2 basal diets containing 2 levels of PDIE (LP or HP) and 2 different infusions of AA mixtures (AA- or AA+) in the duodenum. The AA+ mixture contained Lys, Met, Leu, His, Ile, Val, Phe, Arg, Trp, and Glu, whereas the AA- mixture contained Glu, Pro, and Ser. The infusion mixtures were iso-PDIE. The diet plus infusions provided 13.9 versus 15.8% of crude protein that corresponded to 102 versus 118g/kg of dry matter of PDIE in LP and HP treatments, respectively. The treatments were designed as a 2×2 crossover design of 2 levels of PDIE supply (LP vs. HP) with 28-d periods. Infusions of AA in the duodenum (AA- vs. AA+) were superimposed to diet within each 28-d period according to 2×2 crossover designs with 14-d subperiods. Increasing the PDIE supply tended to increase milk protein yield; however, the efficiency of PDIE utilization decreased and the plasma urea concentration increased, indicating a higher catabolism of AA. The AA+ treatments increased milk protein yield and content similarly at both levels of protein supply. This was explained by an increase in the mammary uptake of all EAA except His and Trp. The mammary uptake of non-EAA (NEAA) was altered to the increase in EAA uptake so that the total AA uptake was almost equal to milk protein output on a nitrogen basis. The ratio between NEAA to total AA uptake decreased from 46% in LPAA- to 40% in LPAA+, HPAA-, and HPAA+ treatments. The PDIE efficiency tended to increase in the AA+ versus the AA- treatments because the NEAA supply and the amount of NEAA not used by the mammary both decreased. Nevertheless, our AA+ treatments seemed not to be the ideal profile: the mammary uptake-to-output ratio for Thr was higher than 1 in LPAA-, but it decreased to 1 in all the other treatments, suggesting that Thr was deficient in these treatments. Conversely, an excess of His was indicated because its uptake was similar in AA+ and AA- treatments. In conclusion, balancing the EAA profile increased milk protein yield and metabolizable protein efficiency at both levels of protein supply by increasing the mammary uptake of EAA and altering the NEAA uptake, leading to less AA available for catabolism.

In vivo inhibition followed by exogenous supplementation demonstrates galactopoietic effects of prolactin on mammary tissue and milk production in dairy cows.

It has been previously shown that the long-term inhibition of milking-induced prolactin (PRL) release by quinagolide (QN), a dopamine agonist, reduces milk yield in dairy cows. To further demonstrate that PRL is galactopoietic in cows, we performed a short-term experiment that used PRL injections to restore the release of PRL at milking in QN-treated cows. Nine Holstein cows were assigned to treatments during three 5-d periods in a 3×3 Latin square design: 1) QN: twice-daily i.m. injections of 1mg of QN; 2) QN-PRL: twice-daily i.m. injections of 1mg of QN and twice-daily (at milking time) i.v. injections of PRL (2µg/kg body weight); and 3) control: twice-daily injections of the vehicles. Mammary epithelial cells (MEC) were purified from milk so that their viability could be assessed, and mammary biopsies were harvested for immunohistological analyses of cell proliferation using PCNA and STAT5 staining. In both milk-purified MEC and mammary tissue, the mRNA levels of milk proteins and BAX were determined using real-time reverse-transcription PCR. Daily QN injections reduced milking-induced PRL release. The area under the PRL curve was similar in the control and PRL injection treatments, but the shape was different. The QN treatment decreased milk, lactose, protein, and casein production. Injections of PRL did not restore milk yield but tended to increase milk protein yield. In mammary tissue, the percentage of STAT5-positive cells was reduced during QN but not during QN-PRL in comparison with the control treatment. The percentage of PCNA-positive cells was greater during QN-PRL injections than during the control or QN treatment and tended to be lower during QN than during the control treatment. In milk-purified MEC, κ-casein and α-lactalbumin mRNA levels were lower during QN than during the control treatment, but during QN-PRL, they were not different from the control treatment. In mammary tissue, the BAX mRNA level was lower during QN-PRL than during QN. The number of MEC exfoliated into milk was increased by QN injections but tended to be decreased by PRL injections. Injections of PRL also increased the viability of MEC harvested from milk. Although PRL injections at milking could not reverse the effect of QN treatment on milk production, their effects on cell survival and exfoliation and on gene expression suggest that the effect of QN treatment on the mammary gland is due to QN's inhibition of PRL secretion.

Alteration of the nutrient uptake by the udder over an extended milking interval in dairy cows.

Little is known about modifications of the mammary utilization of nutrients circulating in blood plasma when milk yield is strongly decreased by once-daily milking. A trial was carried out to describe the mammary nutritional adjustments linked to the downregulation of milk synthesis as milk accumulated over an extended milking interval in the bovine udder. Three Holstein dairy cows yielding 34.0 kg/d of milk were fitted with an ultrasound flow probe around the left external pudic artery and with catheters inserted into the left carotid and milk vein to estimate mammary blood flow (MBF) and mammary uptake of acetate, ß-hydroxybutyrate, nonesterified fatty acids, glycerol, glucose, O(2), and CO(2) release. The trial was carried out over 2 consecutive weeks, with wk 2 repeating wk 1. Cows were milked twice daily at 12-h milking intervals. On d 3, cows were milked at 0630 h and were not milked for 36 h until d 4 at 1830 h. Over the following days, twice-daily milking was resumed using 12-h milking intervals. Each half-udder was milked separately. Secretion rates of milk and milk proteins decreased 67% during the 12-to-36-h interval of milk accumulation, whereas that of milk fat fell 30%. Timing of changes in MBF and lactose levels in blood plasma was concomitant and significant after 19.5 and 21.5h of milk accumulation in the udder, respectively. The MBF decreased, most likely because the usual increases in MBF no longer occurred when the udder was full of milk. After 24h of milk accumulation, MBF did not increase further when cows lay down, and did not increase as usual 3h after a meal, suggesting a possible physical effect of milk accumulated in the udder on MBF, complementing metabolic regulation. Mammary uptake or release of nutrients was lowered before 24h for glucose, acetate, and ß-hydroxybutyrate and after 24h for total glycerol, O(2), and CO(2), mostly associated with the impaired MBF. However, these decreases ranged from 12 to 17%, and cannot entirely explain the -45 and -20% decreases in milk secretion rates observed during the entire 36 h of milk accumulation, thus confirming the primary role of intramammary metabolic regulation in the downregulation of milk secretion. The larger amount of nutrients taken up by the udder could explain the enhanced milk fat levels, involving a strongly modified metabolic fate of nutrients.

A multiparametric approach to assessing residual pain experienced by dairy cows undergoing digestive tract surgery under multimodal analgesia.

This study assessed residual pain responses of dairy cows undergoing fistulation surgery under multimodal analgesia using a multiparametric method combining behavioural and physiological indicators. A longitudinal study was conducted on five dairy cows, each acting as her own control. The surgery consisted of implanting a ruminal and a duodenal cannula in each cow. The multimodal drug protocol consisted of a combination of N-Methyl-D aspartic Acid antagonists, α2-agonists, and local anaesthetic during surgery, and non-steroidal anti-inflammatory drugs (NSAIDs) and opioid treatment postsurgery. Cow responses to surgery were monitored by direct behavioural observation, physiological assay indicators, and milk production from day (D) -6 days before surgery (D-6) to D13 postsurgery. From the data recorded, the variables that contributed most to the discrimination of days pre- and postsurgery were identified using factorial discriminant analysis. Components 1 and 2 of the factorial discriminant analysis explained 68.2% and 17.9%, respectively, of the total variance. Component 1 was mainly explained by haptoglobin (contribution to axis: 0.885), oxidative stress (ratio of oxidized gluthatione to reduced glutathione (GSH/GSSG), -0.746; vitamin E, -0.683; vitamin A, -0.597; malondialdehyde (MDA), 0.416), and behavioural indicators (general attitude, 0.594). On this axis, the higher the score, the higher were the apathy and haptoglobin and MDA concentrations, and the lower were the GSH/GSSG ratio and concentrations of vitamins A and E. This axis opposed cows on D-6 to cows on D3 and D5; cows on D1 and D13 were intermediate. Component 2 was mainly explained by the Hypothalamic-pituitary-adrenal axis (non-esterified fatty acid (NEFA), 0.686; cortisol, 0.669), milk yield (-0.725), oxidative stress (MDA, -0.584; nitric oxide (NO), 0.454), and behavioural indicators of pain (ear position, 0.467; leg postures, 0.431). On this axis, the higher the score, the higher the NEFA, cortisol, and nitric oxide concentrations; the more the ear and leg pain postures; and the lower the milk production and MDA concentrations. This axis opposed cows on D13 to cows on D1. These results suggest that cows may experience some pain only on D1, whereas on subsequent days, the inflammatory response and oxidative stress did not seem to be associated with pain. Our results should be considered for different surgeries to improve analgesia immediately after surgery, and to provide antioxidants along with NSAIDs to promote recovery.

Evaluation and application of potential schistosome-associated morbidity markers within large-scale mass chemotherapy programmes.

A primary objective of schistosomiasis control programmes is to achieve, and hence also demonstrate, a quantifiable reduction in schistosome-associated morbidity as a consequence of chemotherapeutic intervention. Inherent within such an objective, it is necessary to define and validate direct and indirect indicators of schistosome-related morbidity. However, to define and thereby document such morbidity, and its reduction following treatment, may not be straightforward, particularly for intestinal schistosomiasis-induced morbidity, which is often not apparent in all but the most severe or chronic cases. Within all 'Schistosomiasis Control Initiative' activities, across selected sub-Saharan African countries since 2002, a range of standard and novel potential morbidity markers have been monitored and evaluated. Parasitological intensity measures, combined with haemoglobin/anaemia counts and ultrasonography, proved valuable schistosomiasis-related morbidity indicators, being both logistically practical and informative. Additional measures tested, such as albumin excretion profiles, were promising, and are subject to ongoing research, whilst some measures, such as distended stomach/umbilical circumference, anthropometrics and health questionnaires proved less reliable. These results serve to both illustrate the success of current control activities in reducing schistosome-induced morbidity, and to highlight key tools and techniques for continued application within ongoing and future mass drug administration programmes.

Specificity of the Toxoplasma gondii-altered behaviour to definitive versus non-definitive host predation risk.

The hypothesis that the parasite Toxoplasma gondii manipulates the behaviour of its intermediate rat host in order to increase its chance of being predated specifically by its feline definitive host, rather than a non-definitive host predator species, was tested. The impact of a range of therapeutic drugs, previously demonstrated to be effective in preventing the development of T. gondii-associated behavioural and cognitive alterations in rats, on definitive-host predator specificity was also tested. Using a Y-shaped maze design, we demonstrated that T. gondii-associated behavioural changes, apparently aimed to increase predation rate, do appear to be specific to that of the feline definitive host--there were significant and consistent differences between the (untreated) infected and uninfected rats groups where T. gondii-infected rats tended to choose the definitive host feline-predator-associated maze arm and nest-box significantly more often than a maze arm or nest-box treated with non-definitive host predator (mink) odour. Drug treatment of infected rats prevented any such host-specificity from being displayed. We discuss our results in terms of their potential implications both for T. gondii epidemiology and the evolution of parasite-altered behaviour.

Adaptations of mammary uptake and nutrient use to once-daily milking and feed restriction in dairy cows.

The aim of this study was to gain a clearer understanding of the different levels of regulation involved in the reduction in milk yield in response to once-daily milking and feed restriction. The treatments were designed as a 2 x 2 factorial arrangement of 2 milking frequencies (once- or twice-daily milking) and 2 feeding levels (70 or 98% of requirements determined 1 wk before the trial). The cows were surgically prepared to study the net mammary balance of the nutrients that are precursors of milk components. Mammary efficiency in synthesizing milk components was estimated using a milk output:mammary uptake ratio. No interaction was observed between the effects of milking frequency and feeding level on milk and blood parameters except for milk protein yield, milk fatty acid profile, and nonesterified fatty acids metabolism. Once-daily milking and feed restriction reduced milk yield by 5.1 and 2.9 kg/d and fat-corrected milk yield by 4.2 and 4.1 kg/d, respectively. Both treatments induced a decrease in mammary blood flow. Once-daily milking led to a reduction in the extraction rate of glucose but no changes to the lactose output:glucose uptake ratio. Feed restriction did not change the glucose extraction rate but tended to improve the lactose output:glucose uptake ratio. Under once-daily milking, the slight increase in milk fat content (0.34 percentage units) was linked to a depressed uptake of glucose and acetate but without any variations in the uptake of beta-hydroxybutyrate and total glycerol and in the efficiency of acetate and beta-hydroxybutyrate conversion to short- and medium-chain fatty acids in milk. The decline in milk fat and protein contents (-0.43 and -0.23 percentage units, respectively) under feed restriction was associated with relatively similar reductions in the mammary uptake of all nutrients and with enhanced conversion of the glucose taken up by the mammary gland and used for lactose synthesis. As a result, once-daily milking and feed restriction seem to affect milk yield through mechanisms that may be different and relatively independent.

Effects of rumen or duodenal glucose infusions on intake in dairy cows fed fresh perennial ryegrass indoors.

The aim of this study was to determine whether the intake of fresh highly digestible ryegrass could be limited by the total amount of energy absorbed. Moreover, it investigated whether the limitation was more specific to energy absorbed as volatile fatty acids in the rumen compared with energy absorbed in the lower gastrointestinal tract. Four treatments were compared: infusion of 1.25 kg of glucose into the rumen (R1.25), infusion of 2.5 kg of glucose into the rumen (R2.5), infusion of 1.5 kg of glucose into the duodenum (D1.5), and a control treatment consisting of water and salts. Treatments R2.5 and D1.5 were assumed to supply about 16.5 MJ of net energy for lactation. All treatments consisted of 2 infusions, one into the rumen and the other into the duodenum, with one of these infusions being a control. All infused solutions were isoosmotic with osmolarities around 340 and 330 mmol/L for rumen and duodenum, respectively. Treatments were compared using 4 dairy cows in mid lactation according to a 4 x 4 Latin square design replicated twice during 8 periods of 7 d each. Cows were housed in tie stalls and fed ad libitum with fresh perennial ryegrass cut every morning during the spring at 28 d of regrowth. Intake and feeding behavior were measured, as well as concentrations of ruminal fermentation products and some blood metabolites. The pepsin-cellulase organic matter digestibility of the offered herbage averaged 0.76 +/- 0.011. The average dry matter intake of herbage was 15.5 +/- 0.52 kg/d. The glucose infusions decreased dry matter intake by 0.95 kg/d compared with the control, but had the same satiating effect regardless of site or dose of infusion. The average concentration of volatile fatty acids in rumen fluid was 97.9 +/- 2.03 mmol/L and the molar proportion of propionate was 21.6 +/- 0.19 mmol/100 mmol. Glucose infusions into the rumen led to a decrease in the molar proportions of acetate from 64.4 on the control treatment to 60.9 mmol/100 mmol on R2.5 and increased the molar proportions of butyrate from 10.2 (control) to 13.5 mmol/100 mmol on R2.5, and minor acids (valerate and caproate), from 1.27 (control) to 2.54 mmol/100 mmol on R2.5, proportionally to the dose infused. These results suggested that energy nutrients can limit intake in dairy cows fed high-digestibility ryegrass and that butyrate and minor acids would have a limited satiating effect compared with propionate.

Parasites as causative agents of human affective disorders? The impact of anti-psychotic, mood-stabilizer and anti-parasite medication on Toxoplasma gondii's ability to alter host behaviour.

With increasing pressure to understand transmissible agents, renewed recognition of infectious causation of both acute and chronic diseases is occurring. Epidemiological and neuropathological studies indicate that some cases of schizophrenia may be associated with environmental factors, such as exposure to the ubiquitous protozoan Toxoplasma gondii. Reasons for this include T. gondii's ability to establish persistent infection within the central nervous system, its ability to manipulate intermediate host behaviour, the occurrence of neurological and psychiatric symptoms in some infected individuals, and an association between infection with increased incidence of schizophrenia. Moreover, several of the medications used to treat schizophrenia and other psychiatric disease have recently been demonstrated in vitro to possess anti-parasitic, and in particular anti-T. gondii, properties. Our aim here was thus to test the hypothesis that the anti-psychotic and mood stabilizing activity of some medications may be achieved, or at least augmented, through their in vivo inhibition of T. gondii replication and invasion in infected individuals. In particular we predicted, using the epidemiologically and clinically applicable rat-T. gondii model system, and following a previously described and neurologically characterized 'feline attraction' protocol that haloperidol (an anti-psychotic used in the treatment of mental illnesses including schizophrenia) and/or valproic acid (a mood stabilizer used in the treatment of mental illnesses including schizophrenia), would be, at least, as effective in preventing the development of T. gondii-associated behavioural and cognitive alterations as the standard anti-T. gondii chemotherapeutics pyrimethamine with Dapsone. We demonstrate that, while T. gondii appears to alter the rats' perception of predation risk turning their innate aversion into a 'suicidal' feline attraction, anti-psychotic drugs prove as efficient as anti-T. gondii drugs in preventing such behavioural alterations. Our results have important implications regarding the aetiology and treatment of such disorders.

Predisposing factors for the diabetic hyperosmolar state.

To better understand risk factors for the development of diabetic hyperosmolar state (DHS), we studied 135 patients with DHS and 135 age-matched randomly selected diabetic controls admitted to two general hospitals during an 11-year period. To be eligible for the study, patients had to have a hospital admission glucose level of greater than 600 mg/dL (33.3 mmol/L) and an osmolality of greater than 325 mOsm/L (32.5 mmol/L). Patients were significantly more likely than controls to be female (71% vs 53%), to be nursing-home residents (28% vs 15%), to be newly diagnosed diabetics (36% vs 7%), to have a history of dementia (18% vs 8%), and to have an acute infection at the time of admission to the hospital (39% vs 19%). Multivariate analysis revealed three significant independent predictors of DHS: female gender, newly diagnosed diabetes, and acute infection; nursing-home residence and dementia had no independent effect. Other functionally debilitating diseases, acute illnesses, or medications that may impair glucose tolerance were not significantly associated with DHS.

Thyrotropin-releasing hormone release from rat pancreas is stimulated by serotonin but inhibited by carbachol.

Immunoreactive TRH (IR-TRH) has been found in the mammalian pancreas, with several studies documenting high concentrations in the late fetal/early neonatal period. As the factors regulating pancreatic TRH synthesis and release have not been fully explored, we developed a monolayer culture system of dissociated fetal/neonatal rat pancreatic cells to study the release of TRH from the mammalian pancreas. IR-TRH was detected in the culture medium and the IR material appeared authentic based on parallelism with synthetic TRH in RIA and retention time on HPLC. Potassium-induced depolarization (60 mM KCl) resulted in a 170% increase in TRH release compared to that by the Krebs-Ringer bicarbonate control (P less than 0.05). Serotonin stimulated TRH release, with the maximal effect seen with 10(-6) M (130% increase compared to control; P less than 0.05). Carbachol resulted in a dose-dependent inhibition of TRH release (57% inhibition of release at 10(-8) M; P less than 0.01 compared to control). There was no effect on release with norepinephrine, epinephrine, dopamine, gamma-aminobutyric acid, or histamine. We conclude the following. 1) Authentic TRH is secreted by fetal/neonatal rat pancreatic cells in culture. 2) The secretion of TRH is stimulated by potassium-induced depolarization in a calcium-dependent manner, suggesting a classic neurosecretory process of release. 3) The secretion of pancreatic TRH may be under specific neurotransmitter control, with serotonin stimulating and acetylcholine inhibiting release of the tripeptide.

Role of a long-acting somatostatin analogue (SMS 201-995) in the treatment of acromegaly.

The beneficial effect of the long-acting analogue of somatostatin SMS 201-995 in the treatment of acromegaly is described in three cases, and current published experience is reviewed. A total of 64 patients from 10 series have received the drug from one to 25 months, usually in doses of 50-150 micrograms every eight hours by subcutaneous injection. Clinical and chemical improvement was observed in the majority of subjects but normal 24-hour serum growth hormone levels were achieved in no more than 35 percent of this group and possibly less. We have found that higher doses, up to 1,500 micrograms per day, which have generally been free of side effects, are sometimes required to normalize growth hormone secretion. A reduction of up to 33 percent in pituitary tumor size has been reported in more than half of the 27 cases studied from four groups. Clinically important side effects are infrequent, but diarrhea, usually transient, occurred in about 13 percent, with frank steatorrhea in 2 to 6 percent of cases. Alteration in carbohydrate metabolism, such as transient glucose intolerance at the start of therapy in non-diabetic acromegalic patients, and increased sensitivity to insulin or oral hypoglycemic agents in diabetic acromegalic patients, is common. Overall, SMS 201-995 appears to be a valuable new agent for the treatment of acromegaly, but long-term safety needs to be established.

Prognostic factors in the diabetic hyperosmolar state.

To evaluate the current outcome of patients hospitalized with diabetic hyperosmolar state (DHS), we retrospectively studied 135 patients admitted to two general hospitals over an 11-year period. Mortality was 17%. Patients who died had a mean age of 77 years, compared to 68 years for the survivors (P = 0.008). They were also more likely to be nursing home residents (48 versus 23%, P = 0.01). Additionally, mean serum osmolality was significantly higher among those who died (383 versus 358 mosm/L, P less than 0.0001) as was blood urea nitrogen (81.3 versus 62.3 mg/dl, P = 0.006) and sodium (148 versus 137.4 mEq/L, P less than 0.001). However, mean glucose level and anion gap were similar among patients who died and patients who survived (1068 versus 1092 mg%; 23 versus 24 mEq/L, respectively). The presence of a chronic disease or an acute comorbid illness was not associated with mortality. Diminished physiologic reserve, attendant comorbidity, or functional disability may explain the effect of age and nursing home residence. High osmolality may indicate a greater water deficit and a more advanced stage of DHS at the time of diagnosis.