Community analysis of biting midges (Culicoides Latr.) on livestock farms in Denmark.

This study presents descriptive statistics and community analysis of adult biting midges trapped at 16 livestock farms by means of light traps on Zealand and Lolland-Falster, Denmark. A total of 9,047 male and female Culicoides divided into 24 species, were caught. Biotic and abiotic factors ranging from presence of different host species (cattle or sheep/goats), presence of small woody areas or wetlands in the surrounding landscape, and agricultural practice (organic or conventional) were included in the community analysis. Only differences in the Culicoides communities between conventional and organic practices were tested significantly different. Total numbers of Culicoides individuals were higher on the organic farms than on the conventional farms. The larger loads of biting midges on the organic farms may be due to free-ranging animals that attracted the midges on pastures and carried them to the stable environment (the cattle of the conventional farms were held inside the stables). Presence of deciduous trees within 500 m of the farms resulted in higher numbers of Culicoides obsoletus s.s., while presence of wetlands increased the numbers of Culicoides punctatus and Culicoides pulicaris. Furthermore, Culicoides riethi and Culicoides puncticollis (subgenus Monoculicoides) were recorded in high numbers on individual farms. C. puncticollis was found for the first time in Denmark and so far only recorded from Zealand.

Dehalogenation of 4 - Chlorobenzoic Acid by Pseudomonas isolates.

Twenty three bacterial isolates either pure or consortium were initially screened on the basis of their ability to degrade as well as dechlorinate 4 - chlorobenzoic acid (4-CBA). Based on comparative growth response, three pure isolates Pseudomonas putida GVS-4, Pseudomonas aeruginosa GVS-18 and Pseudomonas aeruginosa GWS-19 and a consortium SW-2 was finally selected for further studies. The enzyme studies performed with cell free extracts revealed that dehalogenase activity was substrate specific with maximum activity at 300 µgml(-1) substrate concentration. Catechol 1,2 dioxygenase activity was found to be present in cell free extracts suggesting that 4 - chlorobenzoic acid (4-CBA) is catabolized by ortho-ring cleavage pathway. The dehalogenase enzyme profile showed single enzyme band in case of GVS-4 (Rm 0.76), GVS-18 (Rm 0.84), GWS -19 (Rm 0.85) and two bands in SW-2 (Rm 0.71 & 0.10).

Effect of the alpha 2-adrenergic antagonist yohimbine on orthostatic tolerance.

We studied the effect of yohimbine, a drug that inhibits presynaptic alpha 2-adrenergic receptors and increases the neuronal release of norepinephrine from the central and sympathetic nervous systems, on tolerance to cardiovascular stress in 10 untrained, healthy subjects. Using radioligand binding of tritiated yohimbine to platelets, these subjects were found to have a normal complement of alpha 2-adrenergic receptors (174 +/- 18 [+/- SEM] receptors/platelet) with normal Kd (1.93 +/- 0.17 nmol/l). Lower body negative pressure was used to test responses to cardiovascular stress in the subjects after they received either placebo or 20 mg yohimbine. Graded lower body negative pressure from 0 to -40 mm Hg significantly decreased systolic blood pressure from 116 +/- 3.7 to 106 +/- 5.8 mm Hg, increased heart rate from 54 +/- 3 to 68 +/- 7 beats/min, decreased forearm blood flow from 1.8 +/- 0.21 to 1.36 +/- 0.25 ml/100 ml/min, and increased forearm vascular resistance from 55.76 +/- 12.1 to 77.26 +/- 15.8 mm Hg/ml/min. Yohimbine increased the blood pressure at rest and during lower body negative pressure, but these changes were not significantly different from values recorded from the individuals when they were given placebo. Compared with placebo, however, yohimbine significantly increased forearm blood flow at rest (1.80 +/- 0.21 vs. 2.66 +/- 0.31 ml/100 ml/min, p less than 0.05) and during -40 mm Hg of lower body negative pressure (1.36 +/- 0.25 vs. 1.91 +/- 0.28 ml/100 ml/min, p less than 0.05). We also found that yohimbine significantly increased the plasma insulin concentration in these fasted subjects (9.4 +/- 2.4 vs. 14.5 +/- 1.4 ng/ml, p less than 0.05) without inducing hypoglycemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of exercise and conditioning on clotting and fibrinolytic activity in men.

Sixty healthy men in three physical fitness categories (sedentary, on no organized fitness program; joggers, running 5-15 miles/wk; and marathoners, running greater than 50 miles/wk) were evaluated for changes in blood clotting and fibrinolytic activity before and after maximum exercise on a treadmill according to the Bruce protocol. The rate of blood clotting, as measured by prothrombin times, partial thromboplastin times and thrombin times, was accelerated by exercise (all P less than 0.005). The ability of euglobulin clots and plasma clots to lyse incorporated 125I-fibrin, termed 125I-euglobulin clot lysis (IEL) and 125I-plasma clot lysis (IPCL), were used as indexes of fibrinolytic activity. Marathoners had greater increases in fibrinolytic activity with exercise (76% compared with 63% for joggers and 55% for sedentary subjects by IEL; 427% compared with 418% for joggers and 309% for sedentary subjects by IPCL; all P less than 0.05). Fibrin degradation products increased with exercise (P less than 0.005 for the total group of 60 subjects). The absolute concentrations of alpha 2-plasmin inhibitor, alpha 2-macroglobulin, and antithrombin III increased with exercise (all P less than 0.005), but when concentrations were corrected for acute shifts of plasma water during exercise, the quantity of these inhibitors actually decreased (all P less than 0.005). The changes in clotting assays with exercise were not significantly correlated with changes in whole blood lactate, blood pyruvate, or rectal temperatures. Fibrinolytic assays before and after exercise correlated poorly to moderately with blood lactates (IEL: r = 0.441 and r = 0.425, respectively; IPCL: r = 0.294 and r = 0.544, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Vasopressin inhibits diuresis induced by water immersion in humans.

We tested the hypothesis that 1-desamino-8-D-arginine vasopressin (DDAVP), a V2-receptor agonist, could inhibit the diuresis induced by water immersion in humans. Water and electrolyte excretion, plasma atrial natriuretic factor concentration, and plasma aldosterone concentration were measured initially and after 3 h of water immersion in 13 healthy sodium-replete men given either placebo or 20 micrograms of intranasal DDAVP. Guanosine 3',5'-cyclic monophosphate and urea excretion and urine osmolality were also determined. DDAVP inhibited the diuresis induced by water immersion in men: 758 +/- 168 (SE) ml/3 h in the placebo group vs. 159 +/- 28 ml/3 h in the DDAVP group (P less than 0.05). After 3 h of water immersion, plasma atrial natriuretic factor concentrations were increased from 11 +/- 2 to 20 +/- 4 pg/ml in the placebo group and from 14 +/- 2 to 33 +/- 4 pg/ml in the DDAVP group (P less than 0.05). Plasma aldosterone concentrations were decreased from 98 +/- 18 to 45 +/- 6 pg/ml in the placebo group (P less than 0.05) and from 54 +/- 17 to 25 +/- 5 pg/ml in the DDAVP group (P less than 0.05). Despite these changes in aldosterone and atrial natriuretic factor concentrations, which should increase sodium excretion, DDAVP decreased the natriuresis induced by water immersion in humans: 56 +/- 8 meq Na+/3 h in the placebo group vs. 36 +/- 6 meq Na+/3 h in the DDAVP group (P less than 0.05). DDAVP may be used to prevent the diuresis associated with central redistribution of blood volumes that occur during water immersion.(ABSTRACT TRUNCATED AT 250 WORDS)

Associations between mood and specific health composites during U.S. Navy Persian Gulf operations.

Previously conducted field studies using shipboard U.S. Navy personnel during at-sea operations in the Persian Gulf have shown that crew members experience mood changes and degradations in general physical health. The objectives of this study were to: (a) examine the relationship between mood and health complaints among personnel deployed in the Persian Gulf; and (b) extend previous research using specific health composites rather than a general measure of health. Mood was assessed for 104 shipboard volunteers using the Profile of Mood States Tension/Anxiety and Fatigue subscales. Health symptoms were measures using the Environmental Symptoms Questionnaire. Results of multiple regression analyses showed that each of 11 distinct health composites was significantly associated with one or both mood variables. Further, the two mood factors were differentially associated with 9 of the 11 health composites. This study underscores the usefulness of employing multiple specific health measures rather than global measures.

Heat strain during at-sea helicopter operations and the effect of passive microclimate cooling.

Twelve Navy H-3 helicopter aircrew members were monitored (heart rate, skin and rectal temperatures) in both microclimate cooling (ice) vest and non-vest conditions during at-sea operations in the high heat environment of the Persian Gulf. During all flights and flight phases, ambient dry bulb temperatures ranged from 31.0 degrees C (in-flight) to 48.6 degrees C (hover). Heart rate was greatest during hover and on-deck (range: 89.9 to 145.0 beats/min) without an ice vest, yet was significantly reduced with ice (range: 79.7 to 86.0 beats/min) (p less than 0.05). Rectal temperature was not found to be different between vest and non-vest conditions; however, change across flight phases in both conditions was significant (p less than 0.05). Analysis of variance demonstrated significantly lower mean weighted skin temperatures (p less than 0.05) when wearing the ice vest. These data suggest that wearing a protective cooling vest can reduce the heat strain associated with helicopter flight in high heat environments.

Case report of an obsessive-compulsive personality: a precurser to accident proneness.

The social/physiological/psychological review of an aircraft accident involving input of incorrect controls and low-altitude ejection of a student naval aviator enlightened the investigators as to maybe a not-so-uncommon problem--accident proneness resulting from an obsessive-compulsive nonpsychotic personality. Review of the pilot's history reflected a perfectionist attitude since childhood with continuous associated near-serious accidents. Flight training revealed occurrences of over-correction, channelized attention, and denial of errors. With the demands of Naval Aviation that spurs the growth of the perfectionist, normal/abnormal parameters of obsession-compulsion as they present themselves must be cautiously examined.

Physiological responses during shipboard firefighting.

This study determined the level of heat strain experienced by U.S. Navy personnel while combating fires aboard a damage control research ship. Male volunteers (n = 9), wearing the standard Navy firefighting ensemble, were recorded for core temperature (Tre), skin temperatures (weighted mean, Tmsk), and heart rate (HR) during three fire test days. During the tests, air temperatures in the compartment containing the fire to be extinguished averaged 470 +/- 170 degrees C, while air temperatures in the compartment from which the fire was fought ranged from 40 to 125 degrees C. Dressing in the ensemble and execution of preliminary firefighting activities led to a gradual increase in Tre, Tmsk, and HR; while during active firefighting, Tre, Tmsk, and HR increased rapidly. For all tests, the rate of Tmsk rise (8.73 degrees C.h-1) exceeded the rate of Tre rise (2.95 degrees C.h-1), leading to convergence of these values. Average peak values for all tests were: Tre, 39.2 +/- 1.0 degrees C; Tmsk, 39.5 +/- 0.9 degrees C; body heat storage (HS), 2.02 +/- 0.77 kcal.kg-1; rate of HS during firefighting, 170 +/- 92 kcal.m-2.h-1; HR, 186 +/- 13 bpm. Our findings quantify the limits of tolerance of heat strain encountered during shipboard firefighting.

Metoclopramide does not inhibit atrial natriuretic factor-stimulated diuresis in man.

BACKGROUND: An understanding of the reflex hormonal responses that occur with a redistribution of the blood volume upon exposure to microgravity or during water immersion is operationally relevant. Further, dopamine receptor antagonists, which are used in the treatment of the motion sickness induced by microgravity, or at sea, may affect fluid metabolism. Atrial natriuretic factor (ANF) is a potent diuretic and natriuretic hormone that is released following central blood volume expansion in man. ANF is also a potent inhibitor of angiotensin- and potassium-stimulated aldosterone release. HYPOTHESIS: Since ANF-induced diuresis may be mediated by dopamine, we sought to determine whether inhibition of dopamine receptors blocks ANF-induced natriuresis and diuresis. Also, since ANF has been shown to inhibit aldosterone secretion induced by adrenocorticotropic hormone (ACTH) in vitro, we investigated whether ANF decreases aldosterone in man infused with exogenous ACTH. METHODS AND RESULTS: In six healthy, sodium-replete men, infusion of synthetic ANF (0.01 microgram.kg.min, Anaritide, Wyeth Laboratories) significantly increased urine flow from 7.1 +/- 0.7 to 11.7 +/- 1.8 ml.min-1 (p < 0.05) and decreased aldosterone from 74.7 +/- 9.0 to 55.8 +/- 6.5 pg.ml-1 (p = N.S.). Metoclopramide (Met), a dopaminergic antagonist, increased plasma aldosterone from 104.5 +/- 8.9 to 163 +/- 12.5 pg.ml-1 (p < 0.05). ANF-induced diuresis was not inhibited by Met, but ANF significantly inhibited Met-stimulated increases in plasma aldosterone. ANF did not attenuate ACTH-stimulated increases in plasma aldosterone. Also, ANF-induced diuresis and natriuresis were not affected by concomitant infusions of ACTH, but the ANF-induced kaliuresis was significantly attenuated by ACTH. CONCLUSION: These studies suggest: a) Synthetic ANF induces a diuresis, natriuresis and kaliuresis; b) the D2 receptor antagonist Met increases plasma aldosterone; c) ANF-induced diuresis is not subject to dopaminergic blockade with Met, but Met-induced increases in plasma aldosterone are inhibited by ANF; and d) ANF does not attenuate ACTH-stimulated increases in mineralocorticoid production. These studies have operational significance, as they demonstrate that D2 dopaminergic blockade by the antinausea agent metoclopramide does not prevent the effects of increased ANF in response to central volume expansion such as occurs during exposure to microgravity or following water immersion.

Aerobic fitness and susceptibility to motion sickness.

Susceptibility to motion sickness was evaluated in 29 males having high, moderate, and low levels of aerobic fitness. Subjects underwent Coriolis (cross-coupled) vestibular stimulation on a Stille-Werner rotator during a 10 min modification of the Brief Vestibular Disorientation Test (BVDT). Variables evaluated were: spin time before aborting (ST), heart rate (HR), respiratory rate (RR), mean skin temperature (Tsk), subject observation values (SV), and observation values (OV). Aerobic fitness and ST for the total population were inversely related (r = -0.506, p less than 0.01). Difference in ST was significant (F(2.26) = 6.67, p less than 0.01), with the high aerobic group demonstrating an earlier ST and greater SV than the low aerobic group (Student-Newman-Keuls; alpha = 0.05). Analysis of HR, RR, and Tsk between groups revealed limited differences. Based on these data, men with high aerobic fitness appear to have an increased susceptibility to motion sickness.