Group Of Old Animals Research Articles

Some Perspectives on Cataractogenesis from Heavy Charged Particles

Two sets of observations on cataractogenesis in the New Zealand white (NZW) rabbit (Oryctolagus cuniculus) following localized exposure of optic and proximate tissues to heavy ions are reported. The experiments involved measurements of lenticular opacification in young (ca. 9 weeks old) rabbits caused by graded doses (0.5-5.0 Gy) of 460 MeV/u (incident energy) 56Fe ions and the effects of animal age (9 +/- 0.3 week, 1 +/- 0.5 year, and 4.5 +/- 1.3 year) on lenticular opacifications caused by 9 Gy of 400 MeV/u (incident energy) 20Ne ions. In substantiation of earlier results from NZW rabbits exposed to other low- and high-LET radiations, there was a dose-dependent onset of cataractogenesis following 56Fe-ion irradiation, with the highest doses causing the earliest appearance of cataracts. The level of stationary cataracts was also dependent on dose, and preliminary estimates of RBE yield values comparable to those found at similar doses (0.5-5.0 Gy) by others with populations of cultured cells. With increasing age at the time of exposure to 20Ne ions, the onset of lenticular opacification was delayed progressively and the level of stationary cataracts was reduced, but the onset and progression of late cataractogenesis was most rapid in the oldest group of animals. A discussion of the use of cataract measurements in risk assessment is included in this article.

Neurotransmitter effects on body temperature are modified with increasing age

This study reports effects on body temperature, in two different age groups of Sprague Dawley rats, of intracerebroventricular (ICV) administration of prostaglandin E2, noradrenaline, serotonin, dopamine, and carbachol. Young animals (3–5 months) developed fevers in response to administration of prostaglandin E2 (+1.02±0.26°C), while no significant changes in colinic temperature were observed in the older (15–18 months) group of rats. Noradrenaline (10.0 μg), caused a decrease in colonic temperature in the younger group of animals (−2.02±0.70°C), but had no significant effects on the body temperature of the older group. Similarly, differences between the temperature responses of the young as compared with the older group of animals were observed following ICV administration of carbachol, dopamine and serotonin. These data suggest that the roles of these substances in the hypothalamic control of body temperature may be modified with increasing age.

An investigation of the age-related deficits in the febrile response of the rabbit.

The febrile response of the New Zealand White rabbit in animals less than 1 yr old was compared with that in 3-yr-old animals. A reduced febrile response to both endotoxin and live bacteria injected intravenously was observed in the older group of animals. Peripheral vasoconstriction was observed, suggesting the drive to increase body temperature remained. Plasma catecholamines increased significantly in both groups of animals during fever. However, significantly greater increases in plasma epinephrine were observed in the older animals. A significant deficit in catecholamine-induced thermogenesis was observed in the older group of rabbits. This deficit alone does not explain the reduced febrile response, as beta-adrenergic blockade does not suppress the febrile response of young animals. Thus it is suggested that the primary deficit resulting in a reduced febrile response in the 3-yr-old rabbits is due to other age-related changes in the thermoregulatory system.

The morantel sustained release bolus in the control of gastro-intestinal nematodiasis of cattle in Switzerland (preliminary results).

The efficacy of the morantel sustained release bolus was evaluated in 20 first-season grazing calves and 92 cattle in two separate trials. All animals grazed contaminated pastures and were exposed at the time of spring turnout to a risk of infection from gastrointestinal nematodes. In the first study 45 bolus-treated and 47 nontreated control (second or third season) cattle grazed similar but separate communal pastures, while in the second study nine bolus-treated and 11 nontreated control cattle grazed together on a single pasture. Efficacy determinations were conducted by frequent observations throughout the grazing season on faecal worm egg output, serum pepsinogen levels and liveweight gain. In the older group of animals (Trial 1), small differences were recorded between treated and control animals in faecal worm egg output and levels of serum pepsinogen as monitored throughout the grazing season. A significant mean liveweight advantage of 20.27 kg (P less than 0.001) was observed in the bolus-treated group. However, unrecorded pregnancy could not be excluded with certainty as a factor responsible for weight differences. The use of the morantel sustained release bolus provided an adequate protection against parasitic gastroenteritis in the first season grazing calves (Trial 2) despite the fact that bolus-treated animals were co-mingled with control animals. Both the worm egg counts and serum pepsinogen values were lower in the bolus-treated group. The morantel sustained release bolus was well tolerated in both trials.

Enhancement of maze learning in old C57BL/6 mice by dietary lecithin

Maze learning was studied in young and old C57BL/6 mice. One group of old animals was fed lecithin (supplemented with vitamin E). A second group of old mice and the young mice received standard laboratory mouse chow. The mice were tested on a three-choice-point maze. Young mice learned the maze significantly more easily than either group of old mice. Learning in the lecithin-fed old mice was significantly better than in the control group on a standard diet.

Palatability of venison from farmed and feral red deer

AbstractVenison from feral red deer has been exported from New Zealand for many years but the farming of red deer as a commercial enterprise is a recent development. Two independent evaluations, one at the Invermay Agricultural Research Centre and the other at the Meat Industry Research Institute of New Zealand, were carried out to compare the eating qualities of venison from the two sources. Venison from young male red deer raised in three environments (feral, grassfed and feedlot) was analysed for palatability differences. A significant variation (P <0.05) between venison from animals on the same feed was noted. Nevertheless, there was a significant difference (P < 0.05) between venison from feral and grassfed (farmed) deer in the oldest group of animals (27 months) when triangle tests were used. No striking differences between the three venisons in tenderness, juiciness, flavour fullness, flavour acceptability and general acceptability were detected with rating tests although highly significant differences between panelists were found.

Influence of age and milk diet on cadmium absorption from the gut

Cadmium absorption was studied in different age groups of rats (1, 3, 6, and 52 weeks) fed milk or standard rat diet by determining the whole body retention of orally applied 115mCdCl 2. The whole body retention curves determined over 2 weeks after the 115mCd administration showed highest values in newborn rats. All animals on the milk diet had higher retention values than controls. Within each diet group the retention curves declined with age and the lowest values were obtained in the oldest group of animals. These results indicate that age and diet independently influence cadmium absorption and that the highest values in the newborn most probably result from a combined effect of age and milk diet.

Age aspects in the development of vasopressin-induced coronary insufficiency

Electrocardiogram (ECG) changes (enlargement of the T wave, displacement of the S-T segment, disturbances of atrioventricular conduction) arising under the influence of vasopressin in old rats (24–26 months) occur in response to smaller doses of the hormone than in middle-aged (10–12 months) animals. After injection of equal doses the coronary insufficiency was more severe in the older group of animals and was accompanied more often by a disturbance of atrioventricular conduction in the heart of the second to third degree and by distinct disturbances of the hemodynamics.

Some methodological problems in age comparisons of eeg sleep patterns for C57BL/6J mice

Some methodological problems encountered in age comparisons of EEG patterns are discussed in the context of an analysis of open field activity scores before and after preparation for, and recording of EEG sleep patterns. Plasma corticosterone levels 11 days after surgery for EEG electrode implantation were also measured. Activity levels were modified more for three older than for a younger group of animals following surgery/recording sessions. Corticosterone levels were appreciably elevated for the oldest group of animals. The possibility was raised that procedures designed to allow recovery from post surgical shock and adaptation to electrode connections may result in disproportionate differences across age groups.

Altersabhängigkeit der Gefässwandpermeabilität für Makromoleküle bei Kaninchen

In rabbits subdivided in three groups of different age, vitalmicroscopic investigations were performed concerning the comparative studies of the microcirculation and microvessel permeability for proteins. The normal brightfield, incomplete darkfield, and bluelight luminescence techniques were used. Young rabbits showed a typical pattern of protein permeation mainly localized on the venous end of the capillary bed with maximum along the venules and participation of capillaries and small collecting veins. The postcapillary blood flow was marked by a considerable instability because of increased tendency to red cell aggregation and blood flow anomalies. The findings obtained in middle-aged rabbits were similar to the results of young rabbits. The findings in the third group of old animals, however, were clearly different in comparison with group 1. The protein permeability remained restricted on the venules and was remarkably diminished. Consequently, the intravascular luminescence persisted for 1 h and more, and the small vessels appeared very sharply delimitated against the extravascular space because of absence of a perivascular luminescence. The postcapillary blood flow seems to be stabilized, and prestasis was extremely rare. The diminution or absence of a protein passage across the capillary wall and interstitial space of old animals is interpreted as an important component responsible for the aging process of tissues and organs.

The turnover of some S 35-labelled thioamino-acids in animals of various ages

Our investigations concerning the biochemistry of senescence have demonstrated the occurrence in relation to age of numerous biochemical changes, among which disorders in thioamino-acid metabolism and enzyme activity (Oeriu, 1960; 1961; 1962a, b; 1963a; Oeriu and Tigheciu 1961; 1962; 1964) play an important part. Since the administration of cystein appears to shift the biochemical balance in old animals towards a state characteristics of younger ones, (Oeriu, 1963b; 1963c) we have also looked for differences in S 35-thioamino-acid turnover between groups of old animals used as controls and others previously treated with folcysteine.

Chronic effects of ionizing radiations and the hypothesis that irradiation produces aging-like changes in behavior.

Two groups of old monkeys, one group surviving radiition, the other group nonirradiated, were compared for changes in behavior accompanying aging. The 17 rhesus monkeys used as subjects in these experiments consisted of two groups, each comprised of 6 monkeys aged 8.0 to 9.0 yr, and survivors of another group which had received 1100 r of whole-body x rays in 3 doses of 400, 400, and 200 r spaced at yearly intervals. Subjects were trained in a Wisconsin General Test Apparatus (WGTA). The first experiment involved giving old irradiated and nonirradiated monkeys and young nonirradiated monkeys concurrent discrimination problems in a modified retroactive inhibition paradigm. In the 2nd experiment the technique of substituting less for more preferred rewards during intratrial delays was used to test the frustrative effects of substituting inferior rewards or eliminating rewards within trials. The third investigation was designed to determine whether monkeys could learn to shift set, and whether previously irradiated and nonirradiated monkeys could shift with equal facility. ln all these experiments only one finding in any way supported the hypothesis that chronic effects of radiation miniic aging effects. This was the superiority of the performance of the control group over the performance of subjectsmore » with a radiation history in original learning of concurrent discrimination problems in Experiment I. There were, however, several differences between the two groups of old animals not related to the hypothesis on aging, and all of these differences appear consonant with the known changes in behavior of monkeys following irradiation. These negative findings, together with the previous negative findings of the effects of irradiation on learning, suggest that the syndrome caused by irradiation is dissimilar both to the syndrome resulting from aging and the syndrome caused by circumscribed lesions of the central nervous system. The features seen in monkeys irradiated with either whole-body or cortical irradiation are motivational and perceptual. It is concluded that differences between the groups did not suggest that aging-like changes are the chronic consequences of radiation. (BBB)« less

The Lens as an Indicator of Age in the Raccoon

The growth rate of the lens of the eye was studied as a means of determiningf age in the raccoon. One hundred and nineteen raccoons were studied, including 3 embryos, 18 born in captivity, 42 cap- tured in the wild and kept in captivity for varying periods, and 56 wild animals. Ages of all but those born in captivity were estimated, but these estimates are believed to have an error of no more than ? 2 months. Weights of the dried lenses were used to construct a growth curve which will indicate the month of birth for animals less than 12 months of age, and will estimate the relative age composition of groups of older animals. There are several useful techniques for determining the ages of dead and live raccoons (Procyon lotor) from birth through approxi- mately 8 months of age and for separating males and females less than 1 year of age from those of more than 1 year during the hunting and trapping season (Sanderson 1950 and unpublished). No re- liable technique is available for further segregation of raccoons by age after they have passed their first year of life. Lord's (1959) work on the growth rate of the lens of the cottontail rabbit (Sylvilagus floridanus) prompted this study of age-defining capacity of the lens in the raccoon. Acknowledgments.-This is a contribution from Illinois Federal Aid

WATER AND ELECTROLYTE CHANGES IN AGING PROCESS WITH SPECIAL REFERENCE TO CALCIUM AND MAGNESIUM IN CARDIAC MUSCLE

Concentrations of six electrolytes in seven tissues were determined in rats, the ages of which varied from 1 to 36 months, to demonstrate any changes in the electrolyte pattern during the aging process. Of the tissues studied, the electrolyte pattern of cardiac muscle showed the greatest change with age. There was a general decrease in the concentration of all cations and also of one anion, chloride, in this tissue; phosphate was the only ion to remain constant. The electrolyte pattern of the liver also changed considerably with age; the concentration of all cations decreased with the exception of calcium, which showed no variation. The electrolyte concentration of skeletal muscle changed little with age; only potassium and calcium diminished in concentration. The kidney showed an increase in the amount of calcium and phosphorus and a decrease in the level of potassium in the oldest group of animals. The aorta revealed a striking decrease in the magnesium level and a progressive increase in the amount of calcium with age. The electrolyte pattern of serum and brain was constant, except for the concentration of chloride, which was elevated in the serum of the oldest rats. The concentration of water in tissues was generally found to decrease with age.

WATER AND ELECTROLYTE CHANGES IN AGING PROCESS WITH SPECIAL REFERENCE TO CALCIUM AND MAGNESIUM IN CARDIAC MUSCLE

Concentrations of six electrolytes in seven tissues were determined in rats, the ages of which varied from 1 to 36 months, to demonstrate any changes in the electrolyte pattern during the aging process. Of the tissues studied, the electrolyte pattern of cardiac muscle showed the greatest change with age. There was a general decrease in the concentration of all cations and also of one anion, chloride, in this tissue; phosphate was the only ion to remain constant. The electrolyte pattern of the liver also changed considerably with age; the concentration of all cations decreased with the exception of calcium, which showed no variation. The electrolyte concentration of skeletal muscle changed little with age; only potassium and calcium diminished in concentration. The kidney showed an increase in the amount of calcium and phosphorus and a decrease in the level of potassium in the oldest group of animals. The aorta revealed a striking decrease in the magnesium level and a progressive increase in the amount of calcium with age. The electrolyte pattern of serum and brain was constant, except for the concentration of chloride, which was elevated in the serum of the oldest rats. The concentration of water in tissues was generally found to decrease with age.