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At least 55 records · Page 3Linked to original sources
PubMed2003

Pulsed-field gel electrophoresis typing of Campylobacter fetus subsp. fetus from sheep abortions in the Hawke's Bay region of New Zealand.

AIM: To type Campylobacter isolates from sheep abortions from the Hawke's Bay region of New Zealand. METHODS: Campylobacter isolates were collected from aborted sheep fetuses from commercial farms in the Hawke's Bay region. Information on the Campylobacter vaccination status of flocks in the study was collected. Isolates were identified to species level using standard phenotypic tests, then typed using pulsed-field gel electrophoresis (PFGE). RESULTS: Eighty-one C. fetus subsp. fetus isolates were cultured from aborted sheep fetuses from 25 farms and four C. jejuni isolates were cultured from fetuses from three farms. The C. fetus subsp. fetus isolates were classified into six PFGE groups. A single pulsed-field type predominated amongst isolates from 19 of the 25 farms. The C. jejuni isolates comprised two types. CONCLUSIONS: A range of C. fetus subsp. fetus PFGE types was identified, and one type, B1, was found most frequently. Campylobacter fetus subsp. fetus was only isolated from samples from sheep that had not been vaccinated with C. fetus subsp. fetus vaccine that season.

Journal Article↗
PubMed2002

Further studies on the use of allopurinol to reduce plasma uric acid concentrations in the Red-tailed Hawk (Buteo jamaicensis) hyperuricaemic model.

The present paper reports the effects of allopurinol in a raptor hyperuricaemic model. The study was performed as a follow-up to previous experiments wherein allopurinol was used in doses of 100 and 50 mg/kg, and was proved to be toxic at these higher dose rates. To investigate whether 25 mg/kg (semel in die) s.i.d. allopurinol is a safe and effective dose in Red-tailed Hawks (Buteo jamaicensis) to reduce plasma uric acid concentrations, experimental studies were performed using the physiologically occurring postprandial hyperuricaemia. Preprandial and postprandial plasma concentrations of xanthine, hypoxanthine, allopurinol, oxypurinol and uric acid were established by high-performance liquid chromatography at various time intervals after receiving allopurinol (25 mg/kg SID) or placebo. No significant differences were observed between the experimental and the control group. These results indicate that this dose is safe to administer; however, this dose failed to cause a significant effect on plasma uric acid concentrations. Because of the low therapeutic ratio of allopurinol in Red-tailed Hawks, follow-up studies have concentrated on an alternative for the treatment of hyperuricaemia, namely urate oxidase.

Allopurinol↗
PubMed2000

Hawking radiation As tunneling

We present a short and direct derivation of Hawking radiation as a tunneling process, based on particles in a dynamical geometry. The imaginary part of the action for the classically forbidden process is related to the Boltzmann factor for emission at the Hawking temperature. Because the derivation respects conservation laws, the exact spectrum is not precisely thermal. We compare and contrast the problem of spontaneous emission of charged particles from a charged conductor.

Journal Article↗
PubMed2004

Horizon state, Hawking radiation, and boundary Liouville model.

We demonstrate that the near-horizon physics, the Hawking radiation, and the reflection off the radial potential barrier can be understood entirely within a conformal field theory picture in terms of one- and two-point functions in the boundary Liouville theory. An important element in this demonstration is the notion of horizon state, the Hawking radiation being interpreted as a result of the transition of horizon state to the ordinary states propagating outside the black hole horizon.

Journal Article↗
PubMed1991

Fine structure of the pecten oculi of the red-tailed hawk (Buteo jamaicensis).

The pecten oculi of the red-tailed hawk (Buteo jamaicensis) has been examined by light and electron microscopy. In this species the pecten is very large and of the pleated type. It consists of 17-18 accordion folds which are joined apically by a heavily pigmented bridge of tissue which holds the pecten in a fan-like shape, widest at its base. It is situated over the optic nerve head and extends into the vitreous. Within each fold are numerous capillaries, larger supply and drainage vessels and melanocytes. The capillaries are specialized and display extensive microfolds on both the luminal and abluminal borders. The endothelial cell bodies are thin with most organelles present in a paranuclear location. The capillaries are surrounded by thick fibrillar basal laminae which are probably structurally important and which often enclose pericytes. The melanocytes which are most plentiful in the bridge region and peripherally in the pecten, form an incomplete sheath around the capillaries and other blood vessels. These melanocytes are also felt to be fulfilling a structural role within the pecten. The morphology of the pecten of the red-tailed hawk is indicative of a heavy involvement in the transport of materials to the avascular avian retina.

Animals↗
PubMed1971

DDE residues and eggshell changes in Alaskan falcons and hawks.

Eggshell thickness after exposure to DDT was reduced by 21.7 percent in Alaskan tundra peregrines, by 16.8 percent in taiga peregrines, by 7.5 percent in Aleutian peregrines, by 3.3 percent in rough-legged hawks, and not at all in gyrfalcons. Tundra peregrine eggs contain an average of 889 parts of DDE per million (lipid basis); taiga peregrine eggs contain 673 parts per million; Aleutian peregrine eggs contain 167 parts per million; rough-legged hawk eggs contain 22.5 parts per million; and gyrfalcon eggs contain 3.88 parts per million. These changes in eggshell thickness and the pesticide residues reflect different degrees of exposure to contamination. There is a highly significant negative correlation between shell thickness and DDE content in peregrine eggs. Tundra and taiga peregrines have fledged progressively fewer young each year since 1966.

Alaska↗
PubMed2005

Echolocation call intensity in the aerial hawking bat Eptesicus bottae (Vespertilionidae) studied using stereo videogrammetry.

Aerial hawking bats use intense echolocation calls to search for insect prey. Their calls have evolved into the most intense airborne animal vocalisations. Yet our knowledge about call intensities in the field is restricted to a small number of species. We describe a novel stereo videogrammetry method used to study flight and echolocation behaviour, and to measure call source levels of the aerial hawking bat Eptesicus bottae (Vespertilionidae). Bats flew close to their predicted minimum power speed. Source level increased with call duration; the loudest call of E. bottae was at 133 dB peSPL. The calculated maximum detection distance for large flying objects (e.g. large prey, conspecifics) was up to 21 m. The corresponding maximum echo delay is almost exactly the duration of one wing beat in E. bottae and this also is its preferred pulse interval. These results, obtained by using videogrammetry to track bats in the field, corroborate earlier findings from other species from acoustic tracking methods.

Animals↗
PubMed1987

Visceral gout in a rough legged hawk (Buteo lagopus).

Visceral gout is reported for the first time in a rough legged hawk (Buteo lagopus). Urate crystals were present on the pericardium, thoracic and abdominal air sacs, and the ventral surface of the liver. The liver and spleen also had urate crystals throughout the parenchyma. There was no indication of articular or renal involvement. The immediate cause of death in this hawk was not identified, but appeared to result from multiple factors, including the visceral gout.

Animals↗
PubMed1987

Frenkelia sp.-like infection in the small intestine of a red-tailed hawk.

Developmental stages of a Frenkelia sp.-like coccidium were observed in tissue sections of the duodenum, jejunum, and ileum of a naturally infected red-tailed hawk (Buteo jamaicensis borealis) that died and was examined at necropsy. Developmental stages were located in the lamina propria of these tissues. Thirty sporulated sporocysts measured 11.1 X 8.1 microns in tissue sections. Four sporozoites were present in each sporulated sporocyst. The coccidial infection was not a contributing factor in the death of this red-tailed hawk.

Animals↗
PubMed1988

Ketamine-xylazine anesthesia in red-tailed hawks with antagonism by yohimbine.

Five red-tailed hawks (Buteo jamaicensis) were anesthetized at weekly intervals with intravenous ketamine hydrochloride (KET, 4.4 mg/kg) and xylazine hydrochloride (XYL, 2.2 mg/kg). Twenty min after anesthesia, yohimbine hydrochloride (YOH, 0.05, 0.10, 0.20 and 0.40 mg/kg) or a control was administered. All doses of YOH significantly reduced the head-up times (F = 20.84, df = 1,24, P less than 0.0001) and the standing times (F = 12.30, df = 1,24, P less than 0.0001), compared to the control group. The heart and respiratory rates following YOH (all doses) were significantly greater (P less than 0.01) than the anesthetized rates, but were comparable to the rates observed in restrained, unanesthetized hawks. Yohimbine did not appear to have any significant effect on body temperature. Based upon administration of 4.4 mg/kg KET and 2.2 mg/kg XYL, a dose of 0.10 mg/kg YOH was recommended to achieve antagonism without causing profound cardiovascular or respiratory changes.

Adjuvants, Anesthesia↗
PubMed1994

Apparent fatal snakebite in three hawks.

Based on histories and gross and histologic findings, snakebite was diagnosed in three dead raptors submitted for post-mortem examination from northern Florida and southern Georgia (USA). Two immature red-tailed hawks (Buteo jamaicensis) were found next to dead and partially eaten venomous snakes. An adult Cooper's hawk (Accipiter cooperii) was found adjacent to a den containing a cotton-mouth (Agkistrodon piscivorus) and an eastern diamondback rattlesnake (Crotalus adamanteus). Gross findings in all birds consisted of hemorrhage and gangrenous necrosis of one limb. Severe muscular degeneration was seen histologically.

Agkistrodon↗
PubMed1996

Poisoning of bald eagles and red-tailed hawks by carbofuran and fensulfothion in the Fraser Delta of British Columbia, Canada.

During the winter of 1990 in the Fraser Delta of British Columbia, Canada, nine birds of prey were found with symptoms of anticholinesterase poisoning. Immediate surgical removal of crop contents of three birds decreased mortality and recovery time. Chemical analysis was conducted on crop contents, which contained mainly duck parts. A bald eagle (Haliaeetus leucocephalus) contained 200 micrograms/g and a red-tailed hawk (Buteo jamaicensis) 2.2 micrograms/g carbofuran, while the crop of another red-tailed hawk contained 30 micrograms/g fensulfothion. There was evidence that granular carbofuran and fensulfothion persisted long enough in the wet, low pH conditions of the Fraser Delta to kill waterfowl and cause secondary poisoning of raptors several months after application of the pesticides.

Acetylcholinesterase↗
PubMed1983

Toxicity of gentamicin in red-tailed hawks.

Gentamicin sulfate at dosage levels of 10 and 20 mg/kg of body weight was administered twice daily IV to red-tailed hawks. Clinical signs, water consumption, and changes in blood chemical values were monitored. Tissues were examined grossly and ultrastructurally, using light and electron microscopy. Clinical signs of weakness and apnea were attributed to gentamicin-induced neuromuscular blockade in the 20-mg/kg group. Serum values of aspartate transaminase, alanine transaminase, cholesterol, inorganic phosphorus, total protein, albumin, and uric acid increased in some birds. There was a decrease in periodic acid-Schiff staining of proximal tubular brush borders. Increased numbers of cytoplasmic lysosomes, many of which contained myelin figures, in renal epithelial cells were seen at the ultrastructural level. All birds given 20 mg/kg died. Both dosage levels were considered toxic in red-tailed hawks.

Animals↗
PubMed1995

Neuroendocrine responses to real and simulated BA Hawk MK 51 flight.

The effects of psychological workload on the plasma levels of eight neuroendocrine hormones were studied in 5 undergraduate and 5 senior military pilots of the Finnish Air Force (FAF). All subjects performed the same short-term basic flight mission, which included the following: 1) start; 2) ILS-approach in minimum weather conditions; 3) visual approach; and 4) landing. The mission was performed twice: first with the BA Hawk MK 51 simulator with minimal G-forces and after that with a BA Hawk MK 51 jet trainer with Gz-forces below +2. Blood samples were collected 30 min before and 10 min after the mission and were measured for adrenaline, noradrenaline, ACTH, beta-endorphin, prolactin, vasopressin (AVP), atrial natriuretic peptide (ANP), and cortisol. The plasma levels of adrenaline, noradrenaline, ACTH, beta-endorphin, and cortisol did not change significantly in response to simulated or real flight. Plasma prolactin levels increased significantly (p = 0.037) in all subjects after the mission performed with jet trainer, and the increase was especially great in cadets. However, the same mission performed with the simulator did not raise plasma prolactin levels. This finding suggests that the psychological workload in a flight simulator does not correspond to the psychological workload in a real jet trainer, at least not in basic flying. Plasma AVP increased significantly (p = 0.032) after the mission performed with the simulator in cadets; this increase can be described as a "first-time effect." Plasma ANP also increased significantly (p < 0.05) after a real jet trainer flight.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1997

Heart rate responses to real and simulated BA Hawk MK 51 flight.

BACKGROUND: The effects of psychological workload on inflight heart rate were studied in five experienced (flight instructors) and five less experienced (cadets) military pilots of the Finnish Air Force (FAF). METHOD: The subjects performed the same flight mission twice; first with the BA Hawk MK 51 simulator with minimal G-forces and after that with the BA Hawk MK 51 jet trainer with Gz-forces below +2. The mission included: a) 2 min rest after seating; b) take-off; c) ILS approach in the minimum weather conditions (initial, intermediate and final approach); d) landing tour (visual approach); and e) landing. The heart rates were continuously measured using a small portable recorder developed at the University of Jyväskylä, Finland. The R-R intervals were stored and analyzed with an accuracy of 1 ms. The different phases of each flight were marked in the data by using codes given beforehand for each critical event. RESULTS: The take-off resulted in a significant increase in the heart rate from the resting levels both in the cadets and the flight instructors in both planes. In the simulator the heart rate decreased during the initial approach and slightly increased after it during the intermediate approach. Thereafter the heart rate decreased during the landing tour which seemed to be the least psychologically demanding phase of the simulated flight. The heart rate increased again during the landing but did not exceed the heart rates measured during the take-off and the ILS-approach. There were no statistical differences between the groups. In the jet trainer no decrease in the heart rate could be observed immediately after the take-off, unlike in the case of the simulated flight. The inflight heart rate increased during the final approach, decreased during the landing tour and finally increased during the landing. According to the heart rate analysis the final approach was the most loaded phase of the real flight. The changes towards the phases of final approach and landing were greater among the flight instructors. CONCLUSION: There were no statistically significant differences between the mean heart rates during the real and the simulated flight. It is suggested that the heart rate changes for most reflected the changes in cognitive workload.

Adult↗
PubMed1997

The pharmacokinetics of a single intramuscular dose of amikacin in red-tailed hawks (Buteo jamaicensis).

The pharmacokinetic parameters of amikacin were determined in red-tailed hawks (Buteo jamaicensis) following the i.m. administration of a single 20 mg/kg dose. After a rapid absorption phase, mean amikacin serum concentrations peaked at 65 +/- 12 micrograms/ML 30-45 min following injection. The serum amikacin concentrations decreased to 2.3 +/- 2 micrograms/ml at 12 hr postinjection. Amikacin was eliminated with first-order kinetics characteristic of a single-compartment model with a half-life of 2.02 +/- 0.63 hr. The volume of distribution was estimated to be 0.28 +/- 0.03 L/kg. Forty-two isolates of gram-negative bacteria and coagulase-positive Staphylococcus species were cultured from birds of prey presented to the Veterinary Medical Teaching Hospital at the University of California-Davis. The minimum inhibitory concentration (MICs) of amikacin ranged from 0.5 to 8.0 micrograms/ml (mean = 2.5 micrograms/ml). The 20 mg/kg dose used in this study resulted in serum concentrations at or above the MICs for > 12 hr for most of the isolates examined. The heaviest birds had the lowest peak serum amikacin concentrations, and the lightest birds had the highest, despite exact volume replacement for each sample drawn. This observation suggests that doses should be based on factors other than weight alone. Amikacin administered at 15-20 mg/kg/day, either as a single dose or divided into two or three doses, is effective in treating sensitive pathogens of the red-tailed hawk.

Amikacin↗
PubMed2006

Disease ecology in the Galápagos Hawk (Buteo galapagoensis): host genetic diversity, parasite load and natural antibodies.

An increased susceptibility to disease is one hypothesis explaining how inbreeding hastens extinction in island endemics and threatened species. Experimental studies show that disease resistance declines as inbreeding increases, but data from in situ wildlife systems are scarce. Genetic diversity increases with island size across the entire range of an extremely inbred Galápagos endemic bird, providing the context for a natural experiment examining the effects of inbreeding on disease susceptibility. Extremely inbred populations of Galápagos hawks had higher parasite abundances than relatively outbred populations. We found a significant island effect on constitutively produced natural antibody (NAb) levels and inbred populations generally harboured lower average and less variable NAb levels than relatively outbred populations. Furthermore, NAb levels explained abundance of amblyceran lice, which encounter the host immune system. This is the first study linking inbreeding, innate immunity and parasite load in an endemic, in situ wildlife population and provides a clear framework for assessment of disease risk in a Galápagos endemic.

Animals↗