Recent studies on aspergillosis in turkey poults

A review of the studies on aspergillosis in turkey poults at the National Animal Disease Center include limited field studies, pathogenicity studies, and vaccine development. Natural ventilation in turkey rearing houses was effective in reducing airborne propagules of four major fungal genera, but the effectiveness of ventilation appeared to be limited by the width of the building. Aspergillus fumigatus was more effective than A. flavus in producing mortalities in aerosol exposed poults. Toxigenicity of A. flavus did not enhance its pathogenicity, and no apparent aflatoxin production occurred during pathogenesis in infected turkey poults. Spores of A. fumigatus were disseminated quite rapidly in poults exposed to aerosols, and alveolar macrophages from respiratory lavages taken immediately after exposure contained spores of A. fumigatus. Vaccines produced from germlings of A. fumigatus and administered to turkey poults were the most efficacious of five vaccines tested against challenge exposure to aerosols of A. fumigatus spores.     

Effects of stressors on blood glucose and hepatic glycogen concentrations in turkey poults.

1. The putatively stressful procedures of sexing, toe trimming, snood removal, beak trimming and injection of antibiotic solution, as performed in a commercial hatchery, elevated blood glucose levels and depressed hepatic glycogen levels in newly-hatched turkey poults. 2. The first procedure performed, cloacal sexing, was sufficient to elevate blood glucose, but all procedures were required before depression of hepatic glycogen occurred. 3. Blood glucose levels declined in both untreated (INITIAL) and fully-treated (FINAL) poults over a 24 hr holding period. 4. Hepatic glycogen declined with 24 hr holding of INITIAL poults but increased with holding of FINAL poults.     

Effect of ethanol on heart rate and blood pressure in nonstressed and stressed rats

The effect of ethanol on the cardiovascular system (ECG, heart rate, blood pressure) was studied in anesthetized, nonstressed or stressed rats. In anesthetized rats, ethanol showed no effect on heart rate or ECG. In nonstressed rats, ethanol sedated the animals but increased heart rate significantly. This ethanol induced tachycardia seemed the result of a direct stimulation of the sympathetic nerves to the heart. Blood pressure was not significantly affected by ethanol in these nonstressed rats. In stressed rats, marked behavioral excitation and significant increases in heart rate and blood pressure were noted. Ethanol pretreatment calmed the animals considerably during restraint. Ethanol did reduce slightly the stress-induced tachycardia but markedly reduced or antagonized stress-induced blood pressure increases. No major changes in the ECG were noted during these studies with the exception of a few individual animals which showed pathologic ECG responses to ethanol. These data show that ethanol affects cardiovascular functions differently in anesthetized, nonstressed or stressed rats, and that ethanol can significantly reduce or antagonize stress-induced behavioral excitation, tachycardia and hypertension.     

Toxicity of 2-hydrazinoethanol in turkey poults

1. Toxicity of 2-hydrazinoethanol was investigated in turkey poults 2-6 weeks posthatch. 2. Significant depression of body wt was evident at concentrations of the drug as low as 10 ppm. 3. Severe anorexia closely paralleled a highly significant decrease in water intake. 4. A significant increase in the ratio of granulocytes to agranulocytes was seen in poults fed the drug at a dose of 50 ppm. 5. Under the conditions of this experiment, none of the tissues sampled exhibited pathologic changes consistent with drug injury.     

Effect of heavy exercise on spectral baroreflex sensitivity, heart rate, and blood pressure variability in well-trained humans

The aim of the study was to assess the instantaneous spectral components of heart rate variability (HRV) and systolic blood pressure variability (SBPV) and determine the low-frequency (LF) and high-frequency baroreflex sensitivity (HF-BRS) during a graded maximal exercise test. The first hypothesis was that the hyperpnea elicited by heavy exercise could entail a significant increase in HF-SBPV by mechanical effect once the first and second ventilatory thresholds (VTs) were exceeded. It was secondly hypothesized that vagal tone progressively withdrawing with increasing load, HF-BRS could decrease during the exercise test. Fifteen well-trained subjects participated in this study. Electrocardiogram (ECG), blood pressure, and gas exchanges were recorded during a cycloergometer test. Ventilatory equivalents were computed from gas exchange parameters to assess VTs. Spectral analysis was applied on cardiovascular series to compute RR and systolic blood pressure power spectral densities, cross-spectral coherence, gain, and alpha index of BRS. Three exercise intensity stages were compared: below (A1), between (A2), and above (A3) VTs. From A1 to A3, both HF-SBPV (A1: 45 +/- 6, A2: 65 +/- 10, and A3: 120 +/- 23 mm2Hg, P < 0.001) and HF-HRV increased (A1: 20 +/- 5, A2: 23 +/- 8, and A3:40 +/- 11 ms2, P < 0.02), maintaining HF-BRS (gain, A1: 0.68 +/- 0.12, A2: 0.63 +/- 0.08, and A3: 0.57 +/- 0.09; alpha index, A1: 0.58 +/- 0.08, A2: 0.48 +/- 0.06, and A3: 0.50 +/- 0.09 ms/mmHg, not significant). However, LF-BRS decreased (gain, A1: 0.39 +/- 0.06, A2: 0.17 +/- 0.02, and A3: 0.11 +/- 0.01, P < 0.001; alpha index, A1: 0.46 +/- 0.07, A2: 0.20 +/- 0.02, and A3: 0.14 +/- 0.01 ms/mmHg, P < 0.001). As expected, once VTs were exceeded, hyperpnea induced a marked increase in both HF-HRV and HF-SBPV. However, this concomitant increase allowed the maintenance of HF-BRS, presumably by a mechanoelectric feedback mechanism.     

Evaluation of allopurinol as a cardioprotectant in ethanol-fed turkey poults

Cardioprotectant effects of allopurinol were investigated in ethanol-fed poults during induction of cardiomyopathy and during a period of ethanol abstinence. In young poults fed ethanol, allopurinol has an additive effect on depression of growth but has little or no effect on caloric consumption. Allopurinol significantly depresses heart weight and heart weight to body weight ratios in young poults. In poults 5 weeks and older, allopurinol depresses significantly body weight and caloric consumption. Although allopurinol depresses heart weight in older poults, it appears to have little or no effect on heart weight to body weight ratios. Cardioprotective effect of allopurinol is more apparent during the inductive process than during the recovery phase.     

Changes in blood pressure, heart rate and blood constituents during heat exposure in men with elevated blood pressure

Although the vascular volume response of hypertensive men during exercise has been rather well characterized, the effect of resting heat exposure in this patient population has not been examined. This was done in the present report in seven men with high blood pressure (BP) (i.e., diastolic pressure greater than 12 kPa (90 mmHg) upon initial interview) and 5 normotensive control subjects. 50 min after each subject had consumed an amount of water equal to 1% of his body weight, he reclined on a cot. 10 min later the subject was carried into an environmental chamber equilibrated at Tdb = 45 degrees C, Twb = 28 degrees C. Free-flowing venous blood samples were obtained from a cubital vein, and BP and heart rate were measured, before the heat exposure and at 15 min intervals during the experiment. Within 30 min systolic, diastolic and mean BP of the high BP subjects had decreased to normal levels; no BP changes were detected in normotensive subjects. Accompanying this depressor response was an exaggerated elevation in plasma glucose concentration. No alterations were found with haematocrit, plasma osmolality or electrolytes, or total protein and albumin. The data suggest that heat exposure may have been more stressful for the subjects with high BP than for their controls. This finding implies that phasic depressor responses may be as important as phasic pressor episodes in the aetiology of established essential hypertension.     

Ultrastructural features of ethanol-induced cardiomyopathy in turkey poults

Alcoholic cardiomyopathy, characterized by cardiac hypertrophy, was induced in young turkey poults with 5% ethanol. Ultrastructural features included accumulation of glycogen, swollen mitochondria, myofibrillar lysis, increased number of lysosomes, dilated sarcoplasmic reticulum and dense myofibers. Similarity of these alterations to those described in human alcoholic cardiomyopathy confirms the usefulness of the turkey poult as an animal model for this disease syndrome.     

Transient interactions between blood pressure,respiration and heart rate in man

Auto regressive spectral estimation techniques have been used to follow transient interactions between mean blood pressure, respiration and heart rate. This demonstrates that these inter-relationships are variable. It is concluded that while central modulation of heart rate is the major factor in the interactions, when the heart rate is fixed, peripheral modulation of the blood pressure by respiration is clearly demonstrated.     

Evaluation of the hypomagnetic environment effects on capillary blood circulation,blood pressure,and heart rate

The impact of attenuated magnetic field (МF) on human health is a burning issue of present-day cosmonautics. A series of experiments with animals exposed to attenuated MF revealed violent disorders in the development of the cardiovascular system. The purpose of this study was to estimate the effects of hypomagnetic environment (HME) on capillary blood circulation, blood pressure (BP), and heart rate (HR) in healthy humans. Participants (n = 34) were 24 men and 10 women without cardiovascular symptoms. The mean age was 43.3 ± 15.4 years. Thirteen participants, eight men and five women, were randomly selected for a repeated investigation under natural conditions (sham exposure). The mean age in this group was 47.9 ± 18 years. Cardiac rhythm and heart rate were recorded using an Astrocard cardiac monitor (Russia). BP was measured by means of a Tonocard automatic blood pressure monitor (Russia). Capillary circulation was determined using a digital capillaroscope (Russia) with a high-speed CMOS camera (100 frames/s). The duration of HME exposure was 60 min. It has been demonstrated that HME increases capillary circulation rate by 22.4% in healthy humans without cardiovascular symptoms as compared to the records made under natural conditions. There was a significant HR reduction by the end of HME exposure as compared to the measurements taken at the beginning. At the end of the exposure, diastolic BP dropped considerably relative to mid-exposure values; on the contrary, systolic BP significantly increased by the end.     

The effect of dietary aflatoxin on wild turkey poults

Aflatoxins, toxic metabolites of Aspergillus flavus or Aspergillus parasiticus, cause poor feed utilization, decreased weight gains, depressed immune function, liver dysfunction, coagulation abnormalities, and death in a wide variety of species including humans. Conservationists have become concerned that increasingly popular wildlife feeding or baiting practices could expose wildlife to toxic amounts of aflatoxin-contaminated grains. In particular, the effects of aflatoxins on the wild turkey (Meleagris gallopova silvestris) are of concern because the conspecific domestic turkey is highly susceptible to aflatoxins. To evaluate the effect of dietary aflatoxin on wild turkeys, four groups of 4-mo-old wild turkeys were fed diets containing either 0, 100, 200, or 400 micrograms aflatoxin/kg feed for 2 wk in September and October 1996. Aflatoxin-fed poults had decreased feed consumption and weight gains as compared with control poults. Decreased liver-to-body weight ratios, liver enzyme alterations, slightly altered blood coagulation patterns, and mild histologic changes indicated low-level liver damage. Compromise of cell-mediated immunity was indicated by decreased lymphoblast transformation. The effects were apparent in all treatment groups to variable levels, but significant differences most often were found at 400 micrograms aflatoxin/kg feed. This study shows that short-term aflatoxin ingestion by wild turkeys can induce undesirable physiologic changes; therefore, exposure of wild turkeys to feeds containing aflatoxin levels of 100 micrograms aflatoxin/kg feed or more should be avoided.