Head In Dogs Research Articles

Reflex regulation of vascular tone when the brain is isolated and cooled

When a dog's head was isolated humorally and cooled to 24–26° while the rest of the body remained at normal temperature, no significant depression of control over vascular tone was observed.

Respiratory sensitivity to carbon dioxide in cross-circulated dogs.

The effect of CO2 on ventilation was studied in cross-circulated dogs. In these experiments the recipient dog's head was perfused exclusively by arterial blood from the donor dog through anastomoses of the common carotid arteries of the donor to the vertebral arteries of the recipient. The carotid arteries of the recipient dog, as well as its muscles in the neck, were tied. The injection of lipiodol and latex did not reveal leakage from the recipient's head to its body or vice versa. Ventilation and arterial Pco2 of both dogs were determined before, during, and after the inhalation of carbon dioxide of 3, 5, and 7% with 20% oxygen and balance nitrogen by the donor for 20 min or more. The sensitivity of the respiratory centers of both dogs to Pco2 was similar, as indicated by the regression lines relating ventilation in both dogs as a function of arterial Pco2 of the donor dog only. The blood of the recipient's body was hypocapnic when its head was receiving hypercapnic blood. The sensitivity coefficient in both dogs was similar to that of decerebrate dogs during CO2 inhalation. It is inferred that the central CO2 chemoreceptors can account for all the ventilatory response to CO2 inhalation.

A simple dog head holder for use with the Lab Tronics stereotaxic instrument

A simple dog head holder for use with the Lab Tronics stereotaxic instrument has been described.

Possible central action of certain vasoactive agents.

A previously reported ‘cerebral chemoreceptor buffer mechanism’ was investigated by means of the cross-circulated, vascularly isolated dog head preparation. With the carotid sinuses deactivated, the response of the body blood pressure to centrally circulating vasoactive agents was recorded. When high concentrations of these agents were administered to the isolated head, changes in body blood pressure were frequently observed. However, these changes bore no consistent relation to the blood pressure response of the isolated head or of the intact animal. The body blood pressure response to the central action of these agents was trivial in comparison with the consistent reciprocal response mediated by them through the carotid sinus mechanism.

頭部循環灌流法に依るAcetylcholine並びに其他血管拡張剤の中樞作用に関する研究

頭部循環灌流法に依るAcetylcholine並びに其他血管拡張剤の中樞作用に関する研究

Long-term observations of radiation changes in salivary glands and the general effects of 1,000 R. to 1,750 R. of x-ray radiation locally administered to the heads of dogs

Considerable morphologic alteration was observed in the salivary glands of dogs which had received 1,750 r. of 200 kv. x-ray radiation locally to the head. From a total of six dogs which were irradiated, five were sacrificed during a five- to sixteen-month period following exposure and provided the experimental material for histologic study. Normal glands were obtained from seven unirradiated dogs for comparison. Several special fixatives and stains were used in order to adequately observes the nuclei, mitochondria, connective tissue, and various cellular products of the salivary glands. The parotid, submaxillary, and sublingual glands of three dogs which received 1,750 r. and were sacrificed twenty-five, twenty-nine, and thirty-four weeks later were atrophied, fibrosed, and altered in morphologic detail. Except for knowledge of the anatomic areas from which the tissues were taken, or by special staining reactions, it would have been impossible to identify many tissue sections. The severe changes consisted in various grades of obliteration of acini, leaving whorls of nuclei in streaked concentric patterns, fragmented cells, groups of cells without pattern, partly damaged acini in which one or two cells were identifiable and the rest were vacuolated or in signet-ring configuration. A dog receiving the same amount of treatment, which was sacrificed fifty-eight weeks afterward, had much less apparent total damage, but in many areas some of the changes described previously could be found. A dog receiving 1,000 r. and sacrificed sixty-eight weeks afterward had relatively normal-appearing salivary glands. The general changes observed were stomatitis, surface sloughing, and oral hemorrhage in mild to moderate degree, erythema of exposed areas, particularly over the ears and around the eyes, and epilation. Hair grew back in after six to twelve weeks and was light gray in color. Dogs appeared to be moderately distressed after treatment and one animal developed an ulcerating lesion of the neck.

Neurological and electroencephalographic effects of x-irradiation of the head in monkeys.

THE ADULT nervous system is highly resistant to ionizing radiation at dosage levels which severely injure other tissues.* In support of this generalization Eldred and Trowbridge have recently found that x-irradiation of monkeys with totalbody doses of 400 to 800 r failed to induce neurological changes, 3 although radiation sickness and death occurred. 4 It has been shown, however, that higher doses of radiation, when restricted to the heads of monkeys, may result in weakness, apathy, hemiparesis, and hemiplegia. 5 Similarly, tremors, clonic twitching, and epileptoid seizures have been seen after irradiation of the brains of puppies.† Lyman, Kupalov, and Scholz 8 and Nemenov ‡ believed that irradiation of the head in dogs caused impairment of reflex conditioning (Pavlov), while Warren 10 reported a depression of the nervous system in rats after 1,500 r total-body exposure. These investigations, together with case reports in man,s indicate that the central nervous system

新しい頭部循環灌流法とその吟味

A method has been devised for the perfusion of a dog's head connected to its body only by vago-sympathetic trunk and spinal cord. In order to separate completely the vascular system of the head from the body, it was shown to be necessary to transect all the skin and muscles around the neck at the level of occipito-atlantal joint and to occlude A. spinalis anterior and Sinus columunae vertebralis in vertebral canal. The completeness of the blockade of the blood circulation between head and body was checked by the injection of Evan's blue or adrenaline in either side of the circulation. The time course of survival and reactivity to drugs of the brain was also investigated. From the result obtained in 30 experiments it has been convinced that this method is one of the most excellent methods to observe the direct action of drugs upon brain centres.

頭部循環灌流法によるAdrenalin, N-Methylbenzedrin及びEphedrinの中樞作用に關する研究

By means of our method (see this Breviaria, No. 63), the central effect upon blood pressure and respiration of, adrenaline and its homologues injected into the perfusion circuit 'of dog's head was investigated. Adrenaline reduced the systemic blood pressure and the respiratory, movement of the recipient dog. By a given dose of adrenaline, the degree of the fall was shown to be roughly proportional to the initial level. This central inhibitory effects of adrenaline upon both the blood pressure and the respiration were observed not only during the adjustment of the elevated perfusion pressure by adrenaline to preinjection level but also after denervation of vagus and/or carotid sinus nerves. N-Methylbenzedrine and ephedrine given intraarterially to the head, elevated the systemic blood pressure gradually, the effect of the latter being remarkably weaker than the former. The former stimulated the respiration, whereas the latter did not show any stimulation but caused inhibition. 'Both of them dilated slightly the blood vessels of the head.

The Vasodilator Properties of a Pancreatic Extract.

Summary1. Pancreatic extract in concentrations of 0.2 to 1% causes a transient but significant increase in coronary sinus outflow in the denervated and innervated heart-lung preparation. 2. Femoral blood flow in anesthetized cats may be increased by 100 to 650% following doses of 0.005 to 0.02 cc of pancreatic extract injected intra-arterially. The effect lasts no more than 2 or 3 minutes. 3. Doses of 1 cc of pancreatic extract cause a transient dilatation of the arterial bed of the perfused dog head. 4. Doses of 0.01 cc have no regular effect upon arterial pressure when injected intravenously into anesthetized cats. Doses of 0.1 cc cause a 50% fall in arterial pressure lasting only one or 2 minutes, followed by a rise of 25 to 30% above the control level lasting for 3 or 4 minutes. Femoral blood flow appears to follow passively the arterial pressure; vasodilatation probably occurs chiefly in the visceral vascular beds.

Effects of Various Chemical Agents on Survival of Primative Respiratory Mechanism

That young animals are much less susceptible to anoxia than are adults has been well established. Selle and Witten. have shown that the respiratory center of rats, rabbits, cats and dogs is itself much more tenacious and viable in the young than in the adult, and that until approximately 6 weeks of age the survival of the respiratory mechanism of the rat is inversely proportional to age. Following decapitation or ligation of the cerebral vessels, the isolated ischemic head of a full grown rat gasps 5 to 8 times over a period of 10 or 20 sec and thereafter remains motionless; in a week old animal the phenomenon continues for 30 min or more. Unlike adults, rats under 6 weeks of age display 2 periods of respiratory movements: and initial series which consists of 6 to 12 gasps and lasts 20 to 30 sec, and a second series which begins 30 to 50 sec after cessation of the initial of first series and lasts for a variable time depending upon the age. The total number of gasps in both series, as well as the total duration of gasping, is greater the younger the animal. The second series, which is influenced most by age, lasts 30 to 40 min in new-born animals. As age increases, the number of gasps, as well as duration of gasping, diminishes uniformly. Similar observations have been made on ischemic heads of rabbits, cats and dogs. The present study was designed to determine the effectiveness of certain drugs on the activity of this primitive respiratory mechanism. Using a technique previously described for determination of survival of this mechanism, a large number of this mechanism, a large number chemical agents (67) varying widely in composition and action, were injected subcutaneously or intraperitoneally into 12-15-day-old rats (weight 18-26 g). Following an interval ranging from min to several hours

Metabolism in Perfused Dog's Head During Sodium Pentobarbital Depression ann Metrazol Stimulation

SummaryThe results of perfused head experiments show that during sodium pentobarbital depression there is a measurable reduction in both oxygen and glucose utilization. Metrazol administered during this depression returns the utilization of both to about the control levels or beyond.

Another Mayan Hieroglyph for “Day”

Charles P. Bowditch reproduces about seven different signs as hieroglyphs for Kin, “day,” in his fundamental work on the Maya calendar. They are: (1) the sun-disk, (2) the head of the sun-god, (3) the head of a sun-bird, (4) the dog's head, (5) the conch, (6) the inverted Ahau and (7) the composite glyph day-sky, sun-disc and Caban. There can be identified still a few more hieroglyphs as representing the same idea.In this paper we shall treat of a new sign, generally composed of a quincunx (a variant of the character for “greenstone”) and a skull (Figure 1, a, b and f), for which the value “day” can be proved.

Dog's head in the pot

Dog's head in the pot

Changing London: The dog's head in the pot

Changing London: The dog's head in the pot

Some Irish Antiquities of Unknown Use

In Sir William Wilde's Catalogue of Bronze Antiquities is described and illustrated under the heading of chariot furniture an iron-backed bronze disc, 3¾ in. in diameter, coated with white metal, projecting from which is a bronze stud in the form of a dog's head, 1½ in. long, with a human head engraved on its muzzle. The stud is threaded by a bronze chain made up of two rings and double loops (fig. 1, 1). Wilde considered this object was intended for the attachment of a trace. It was found when making a railway cutting near Navan Station adjoining the River Boyne in July 1848, associated with a quantity of human remains; the skull of a horse; a number of antiquities including a bronze bridle-bit, and harness-plate; iron rings plated with bronze; some small bronze buttons; and seven ornamented gilt-bronze plaques.

THE DAY OF THE DOG

IT was on the shore at Qibraltar that we met him, one splendid June morning. Hot, sweltering,-even the Moors from Tangiers were complaining. He was an English dog, property probably of some officer's wife at the citadel on the hill. He had wandered away from Tommy Atkins, however, to mingle with the common herd on His Majesty's highway. But, doggy had a headache and so they had fixed him up. Splendid piece of nursing, is n't it? Notice the care with which the bandage is bound about the head. One sees these dog bandages often in the hot countries, sometimes as a preventive rather than cure, to keep the torrid sunbeams from the dog's head.

The Dog-Headed Opossum

The Dog-Headed Opossum

Dog's Head in the Pot

Dog's Head in the Pot

Dog's head in the pot

Dog's head in the pot