The effect of normal development and of severe undernutrition on some minor components of cortical bone

1. The amounts of calcium, magnesium, sodium and citric acid in the bones of undernourished pigs 1 year old were compared with the amounts in the bones of smaller newborn animals, normal animals of the same weight aged 4 weeks and of the same age weighing 170kg. 2. The differences that were found between 4 weeks and 1 year of age in the normal animals were expected as effects of aging. However, between birth and 4 weeks of age the changes in composition were in the opposite direction to those between 4 weeks and 1 year. 3. Undernutrition produced a bone that resembled chemically that of an animal 1 year old.     

Age Distribution of Naturally Occurring Acute Babesiosis in Cattle in Sweden

The age distribution of clinical cases of babesiosis reported by local veterinary practitioners was investigated in 1976 and 1981. The first study was based on material collected primarily for identifying the Babesia species, the second on computerized reports from a part of one county in Sweden. The results were similar. Most diseased animals, 135/165 (82%) and 145/161 (90%) respectively, were more than 2.5 years old (cows), while 27/165 (169b) and 12/161 (8%) respectively, were 1–2.5 years old and only 3–4 (2–3%) animals were calves less than 1 year old. This age group, however, probably did not meet the same infection risk as did older animals. Among cows (>2.5 years old) there seemed to be no influence of age on the distribution of clinical babesiosis. Calculation based upon the entire animal population of the county investigated in 1981 revealed that clinical babesiosis was reported about 11 times more often among cows than among heifers and steers. The comparatively high resistance among 1–2.5 year–old cattle may be a function of an inverse age resistance, and/or may be influenced by vaccination against babesiosis on »high risk« farms in Sweden and a lower risk of infection on other farms such that animals tend to escape infection prior to adultness. Babesia organisms were found in 156 of 165 cases (95%) reported as clinical babesiosis.     

Age affects hibernation in Syrian hamsters (Mesocricetus auratus)

In this study, we aimed to show how age affects hibernation in the Syrian hamster. Experimentally, we used 30 male animals differing in age. The old animals were 20 months of age and the adults were 8 months of age at the end of the test. The young animals were 3 weeks old at the start of testing and 5 months old at the end of the testing period. The torpor observation started October 15, 1996, and ended March 11, 1997, in the laboratory colony maintained under natural photoperiod and outdoor air. Observations were performed around noon daily. Three measures (i.e., prehibernation period [hibernation latency], proportion of hibernation spent in torpor, and proportion of animals in torpor), all of which reflect the strength of occurrence of hibernation, indicated that the older hamsters (1) started hibernation earlier, (2) spent more time in torpor, and (3) had a higher chance of being in torpor than the younger ones during the hibernation season. (Chronobiology International, 17(5), 623-630, 2000)     

AGE AFFECTS HIBERNATION IN SYRIAN HAMSTERS (MESOCRICETUS AURATUS)

In this study, we aimed to show how age affects hibernation in the Syrian hamster. Experimentally, we used 30 male animals differing in age. The old animals were 20 months of age and the adults were 8 months of age at the end of the test. The young animals were 3 weeks old at the start of testing and 5 months old at the end of the testing period. The torpor observation started October 15, 1996, and ended March 11, 1997, in the laboratory colony maintained under natural photoperiod and outdoor air. Observations were performed around noon daily. Three measures (i.e., prehibernation period [hibernation latency], proportion of hibernation spent in torpor, and proportion of animals in torpor), all of which reflect the strength of occurrence of hibernation, indicated that the older hamsters (1) started hibernation earlier, (2) spent more time in torpor, and (3) had a higher chance of being in torpor than the younger ones during the hibernation season. (Chronobiology International, 17(5), 623–630, 2000)     

Steroid hormone transformation in the gonads and liver of aged rats

In order to study some aspects of the steroid hormone balance in old age the following organ functions of young and senescent male and female animals were investigated: 1) The capacity of testicular (45, 68-75 and 900 day-old animals) and ovarian tissue homogenates (29, 45, 66 and 900 day-old animals) to metabolically transform the sex hormone precursor, progesterone. 2) The capacity of liver slices (60-90 and 900 day-old animals) to generate a sex-specific metabolite pattern during incubation with testosterone. 3) The activities of some enzymes of steroid metabolism, which normally show sex differences in liver cell fractions (60-90 and 900 day-old animals). The testicular capacity of senescent animals to synthesize 17 alpha-hydroxyprogesterone, androstenedione and testosterone (main pathway of androgen biosynthesis) is drastically reduced compared to that of young adult rats; the reduction also extends to the production of highly polar C19O3- and C21O3-steroids. In contrast to these deficiencies, conversion of progesterone to 20 alpha-dihydroprogesterone increases in old age, whereas the generation of 5 alpha-hydrogenated compounds from testosterone and androstenedione remains unchanged. If the group of adolescent 45 day-old animals is also taken into consideration, then the biosynthetic sequence from progesterone to testosterone exhibits a biphasic developmental course. Production rates rise from low levels only to fall back to lower rates of synthesis in old age. In no age group can the production of oestrogens in measurable quantities be detected. However, 5 alpha-hydrogenated C19O2-steroid metabolites are detected, albeit only in prepuberal animals. After puberty only progesterone, 20 alpha-dihydroprogesterone and the 5 alpha-pregnane derivatives of these two steroids can be demonstrated. The pattern of the respective metabolites undergoes an age-dependent metabolite-specific development ending (900 day-old animals) with minimal yields of products (less than 21% of progesterone is converted). The production of hydroxylated metabolites (highly polar C21O3-steroid fraction) decreases very early in life (between day 29 and 45) to values indistinguishable from those of old animals. The sexually highly differentiated metabolite pattern of hepatic testosterone metabolism typical of young adult animals (60-90 day-old) is not prominent in old age. Both sexes exhibit a retarded testosterone turnover due to a decrease in the hydroxylating activity (males being more affected than females) and a deficiency of 5 alpha-hydrogenation (females only).(ABSTRACT TRUNCATED AT 400 WORDS)     

Age Peculiarities of the Calpain/Calpastatin Cerebral System in Rats: Relation to the Hypothesis of Brain Aging

We studied age-related changes in the activity of calpain, those in the activity of its endogenous inhibitor calpastatin, and the ratio of these indices in the brain of rats of four age groups (2-3 weeks, 2-3, 5-6, and 24 months). The activity of calpain was estimated using FITC casein as the substrate. In a soluble fraction of the brain homogenate, the enzyme activity in general increased with age. In mature rats (5 to 6 months old), this index exceeded 3.65 times the corresponding index in juvenile (2 to 3 weeks old) animals, while in old animals this index somewhat decreased. In the fraction obtained after separation of calpain from other components using DEAE-cellulose chromatography, the age-related trend toward an increase in the activity of calpain was preserved, but it was much more moderate. The activity of calpastatin demonstrated an opposite direction of age changes: it was the maximum in 2-3-week-old animals and gradually decreased (by 27%) in old rats. We also found that the efficacy of inhibitory action of calpastatin in the cerebral tissue with respect to the activity of calpain was, as a rule, redundant. In this case, the ratio of inhibitor/enzyme activities decreased with age; this index was 1.65, 1.33, 1.1, and 1.0 or less in 2-3-week-old, 2-month-old, mature, and old animals. Therefore, we found that the intensity of calpain-mediated proteolysis in the rat brain increases from the juvenile period to the mature age and somewhat decreases in old individuals. Such alterations are developed at the expense of both an increase in the activity of the enzyme and weakening of the action of its inhibitor (calpastatin).     

The adrenal medulla and adrenergic innervation of the ventricles of the heart during the postnatal period of ontogenesis of the white rat (histofluorescent study)

The sympathetic innervation of the cardiac ventricles and dynamics of catecholamine contents in the adrenal medulla have been investigated in inbred white rats (1-3-week-old, immature, mature and old animals). During 1-3 weeks of age, development of adrenergic innervation of the heart is observed, in 1.5-month-old rats in approaches that in mature animals. In the old rats the arrangement density and fluorescent intensity of the adrenergic terminals of the cardiac ventricles in comparison to those in the mature animals decreases considerably. Catecholamine contents in the adrenal medulla in 3-week-old rats practically reaches those specific for mature animals. In the old animals the amount of catecholamines in the adrenal medulla decreases by 20%, comparing to those in the mature animals. Thus, maturation of the mediator link of the sympatho-adrenomedullary system is performed in it later than the hormonal one, while processes of old age involution are more intensive.     

Age-dependent use of local and global landmarks during escape: experiments using Columbian ground squirrels

How animals utilize their space often changes during ontogeny, perhaps resulting from alternative use of orientation mechanisms. This study investigated whether landmark-based navigation mechanisms were age-dependent in Columbian ground squirrels (Spermophilus columbianus). In field tests, young (1-2 years old) and adult (3-6 years old) animals had to find an escape burrow when either local, global, or both types of landmarks were obstructed. The comparison of escape times between age groups revealed that adult squirrels found escape burrow faster than young animals if global landmarks were available. However, if only local landmarks were present, young squirrels outperformed older animals. The comparison of escape time within each age group showed that obstruction of global or local landmarks lengthened escape time of adult squirrels. In contrast, young animals had longer escapes only when local landmarks were obstructed. The results suggested that the use of different types of landmarks was age specific.     

Lipid oxidation by heart mitochondria from young adult and senescent rats

1. State-3 (i.e. ADP-stimulated) rates of O(2) uptake with palmitoylcarnitine, palmitoyl-CoA plus carnitine, pyruvate plus malonate plus carnitine and octanoate as respiratory substrate were all diminished in heart mitochondria isolated from senescent (24-month-old) rats compared with mitochondria from young adults (6 months old). By contrast, State-3 rates of O(2) uptake with pyruvate plus malate or glutamate plus malate were the same for mitochondria from each age group. 2. Measurements of enzyme activities in disrupted mitochondria showed a decline with senescence in the activity of acyl-CoA synthetase (EC 6.2.1.2 and 6.2.1.3), carnitine acetyltransferase (EC 2.3.1.7) and 3-hydroxy-acyl-CoA dehydrogenase (EC 1.1.1.35), but no change in the activity of carnitine palmitoyltransferase (EC 2.3.1.21) or acyl-CoA dehydrogenase (EC 1.3.99.3). 3. Measurement of dl-[(3)H]carnitine (in)/acetyl-l-carnitine (out) exchange in intact mitochondria showed decreased rates when the animals used were senescent. However, this followed from a decreased intramitochondrial pool of exchangeable carnitine, such that calculated first-order rate constants for exchange were identical in mitochondria from the two age groups. 4. The decline in acyl-CoA synthetase activity is thought to be the reason for the diminished rate of O(2) uptake with octanoate in senescence. The decline in carnitine acetyltransferase activity is considered to be the cause of the diminished rate of O(2) uptake with acetylcarnitine or with pyruvate plus malonate plus carnitine as substrate. The mechanism of the diminished rate of O(2) uptake with palmitoylcarnitine in senescence is discussed.     

Trace rhythm recruitment by the neurons of the rabbit sensorimotor cortex in old age]

Spectral analysis (ACG and gSP) of the impulse activity of the neurones of the old rabbits sensorimotor cortex allowed to reveal a trace recruitment of the rhythm--CR analogue to time--in after-action f rhythmic stimulation. Connection was established between the number of presented series of periodic electrocutaneous stimulation and expressiveness of the trace rhythm recruitment depending on the animals age. Trace rhythm recruitment took place slower in old animals (54-56 months) than in young ones (up to 1 year), chiefly in 2-3 experimental days after 2-4 series of rhythmic stimulation and was preserved in a small percent of cases the next day after stimulation. In the background activity of a number of neurones an initial periodicity was discovered, which was intensified under the influence of stimulation by another frequency, or the initial rhythm was extinguished, and stimulation rhythm was reproduced. Periodical stimulation in very old animals (66-85 months) practically did not evoke plastic reconstructions of the cortical neurones. Under the influence of the stimulation a non-specific trace increase of the frequency of neurones background activity of the old animals was observed. The revealed characteristics of plastic neurones properties may testify to projected disturbances of mnestic processes at definite age stages of normal aging.     

Estrogen - Induced release of luteinizing hormone in prepubertal and postpubertal heifers

This experiment was designed to determine the age at which estradiol-17beta (E(2)) first induces a preovulatory-like surge of luteinizing hormone (LH) in prepubertal heifers. Responses of prepubertal animals 3 to 4 and 5 to 6 months of age were compared with those of postpubertal heifers that received 25 mg prostaglandin F(2)alpha at 0800 hr on day 15 of the estrous cycle. E(2) (500mug) induced surges of LH in 1 5 heifers 3 to 4 months of age, 3 3 heifers 5 to 6 months of age and 5 5 postpubertal heifers. Duration of response and interval between E(2) injection and peak of the response were longer in postpubertal heifers than in those 5 to 6 months old (P<0.10). Peak response and total amount of LH released were greater in animals 5 to 6 months old (P<0.10). Only one prepubertal heifer had elevated concentrations of progesterone following an LH surge. Four of 5 postpubertal heifers receiving E(2) and 3 of 4 postpubertal heifers receiving corn oil had corpora lutea and similar patterns of progesterone concentrations. We conclude that ability to release an LH surge in response to E(2) develops in heifers between 3 and 5 months of age, but that this induced surge does not cause ovulation.     

The effect of long-term caloric restriction on function of T-cell subsets in old mice

The effect of caloric restriction (from weaning to old age) on CD3-stimulated CD4+ and CD8+ lymphocyte proliferation and calcium mobilization was examined. Young ad libitum (ad lib) fed, old ad lib fed, old calorically restricted, and old calorically restricted mice which were fed ad lib during the last 6 weeks of their life (restricted/refed) were compared in both BDF1 [(C57BL/6 x DBA/2)F1] and C57BL/6 mice. Proliferation of CD4+ cells was lower in old ad lib animals than in young animals; this difference was not seen in CD8+ cells. Those CD4+ cells which did proliferate in old ad lib animals underwent similar cell cycle progression as young cells. In calorically restricted and calorically restricted/refed animals, CD4+ cell proliferation was similar to the young animals, and CD8+ cells showed a higher proliferative capacity than cells from either young or old ad lib mice. Differences in proliferative capacity were not correlated with alterations in transmembrane signaling efficiency as peak [Ca2+]i was reduced in both T-cell subsets in all groups of old mice relative to young mice. Additionally, reduced [Ca2+]i was observed in the CD8+ subset for which there was no deficit in proliferation, and the enhanced proliferation seen in old restricted and old restricted/refed mice did not manifest as increased [Ca2+]i mobilization. The percentage of CD4+ cells from both mouse strains was reduced in all groups of old mice compared with young mice, while the percentage of CD8+ cells was generally similar in young and all groups of old mice. Our studies would suggest that lifelong caloric restriction of mice prevents the age-associated decrease in T-cell proliferative capacity but that the enhanced proliferation of these cells is not due to increased efficiency of transmembrane signaling.     

Tick-Borne Fever in Lambs of Different Ages

Four groups of lambs aged 1 week, 4 weeks, 1/2 year and 1 year old respectively were inoculated with Ehrlichia phagocytophila infected blood. Clinical signs, temperature reactions, haematological changes and parasitaemia were more moderate in lambs inoculated with E. phagocytophila at the age of 1 week than those recorded in the older animals. The clinical response to tick-borne fever (TBF) appears to be more severe with increasing age of the lambs. The lymphocyte reactivity to mitogens was reduced in the TBF infected lambs, and was most pronounced in lambs in the 3 older age groups.     

Action of vasopressin on the electrical and contractile reactions of vascular smooth muscles in animals of various ages

Vasopressin action on isolated strips of the femoral artery was studied in mature and old rats. Vasopressin has been shown to depolarize smooth muscle cells (SMC) membranes, causing the tonic contraction of the strips. SMC sensitivity to vasopressin in old animals was increased, electrical and contractile reactions were also enhanced. Peculiar tachyphylaxia in response to vasopressin has been found in SMC of mature animals. In old animals SMC tachyphylaxia was far less expressed than in mature ones. Two types of vasopressin receptors (V1-exciting and V2-inhibitory) in vascular SMC were suggested. Vasopressin does not influence cAMP content of the femoral artery in mature and old animals. Specific features of SMC reactions to vasopressin in old animals may underlie the mechanisms of cardiovascular pathology in old age.     

Activity of selenium-dependent enzymes in erythroid cells of animals in the postnatal period

The age dynamics of selenium-dependent enzymes glutathione peroxidase and thyroxine-5'-deiodinases type I and II (D1 and D2 respectively) in bone marrow erythroblasts of new-born, 1-, 3-, 5- and 10-day old piglets as well as influences of hormones (thyroxine, cortisol) selenium and iron on enzyme activities were investigated. The enzyme activities in the pig erythroid cells were established to increase after birth. D1 activity increased in erythroblasts of 3-day old piglets, while augmentation of D2 activity was significant in the cells of 10-day old animals. Glutathione peroxidase and thyroxine-5'deiodinase activities in pig erythroblasts decreased under the influence of thyroxine and hydrocortisone in vivo, and increased after injections of sodium selenite. For comparison, activities of 5'-deiodinases in the cells of some other tissues were also investigated.     

Age-related features of the metabolism of fatty acid components of phospholipids of the cell nuclei of rat liver under the effect of dietetic factors

The metabolism of nuclear phospholipid acyl components of liver in uneven-aged rats was studied in vitro under different dietary fat implications. The activity of phospholipases A1 and A2 in the nuclei was found to sharply increase in animals pretreated with excess of fat. The incorporation of labelled palmitic, oleic, linoleic and arachidonic acid into nuclear phospholipids is under control of age and diet manipulations. The observed changes in the level of fatty acids metabolism are more pronounced in cell nuclei of the young rat liver. The lipid composition of cell nuclei in the test 3-month old animals does not differ from that of the control animals. At the same time dietary implications induce deep changes in the composition of nuclear lipids in 24-months old animals.     

Decrease of mu opioid receptors in the brain and in the hypothalamus of the aged male rat

Experiments have been designed in order to analyze whether the binding capability of mu opioid receptors in the brain of the male rat is modified by age. In a first experiment, the number of receptors (Bmax) and the constant of affinity (Ka) for the mu ligand 3H-dihydromorphine (3H-DHM) have been measured in the whole brain of male rats of 2, 15 and 22 months of age. In a second experiment the Bmax and the Ka for 3H-DHM have been evaluated in the hypothalamus of male rats of 2 and 22 months of age. In this experiment it was also investigated whether the administration of exogenous testosterone modifies the number and/or the affinity of the hypothalamic mu receptors. Serum levels of LH, FSH, prolactin and testosterone have been measured by specific RIAs. The results obtained show that: serum testosterone levels are significantly decreased in aged rats, while serum LH and FSH show only a small decline; serum prolactin is higher in old than in young animals; the number of mu receptors in the whole brain of 15 and 22 month old animals and in the hypothalamus of 22 month old rats is significantly lower than in the same tissues of young animals; the administration to old animals of testosterone, in doses able to bring back towards normal serum levels of testosterone, induces a decrease of LH and FSH, but has no effect on serum prolactin titers. Testosterone administration does not modify the number of hypothalamic mu opioid receptors, indicating that the decline of brain mu receptors in old animals is not the consequence of the physiological decline of testosterone secretion; in no instance the Ka for the mu ligand is significantly affected.     

Hormonal requirements and the influence of age on the decidual cell reaction in the bank vole (Clethrionomys glareolus)

Laboratory bred bank voles of different age and reproductive status were bilaterally ovariectomized, treated with exogenous oestrogen or progesterone or both, and given an artificial decidual stimulus (crushing with artery forceps). An hormonal regimen of oestrogen (100 ng) followed by progesterone (1 mg) and small amounts of oestrogen (10 ng) was necessary for maximal development of the decidual cell reaction (DCR). A DCR did not develop if the animals were treated with only oestrogen or progesterone. Middle-aged virgin females 5-7 months old had larger responses than did young virgin females 2-3 months old, and parous females, 15-19 months old and having had at least 10 litters, had a response similar to that of virgin females of about the same age. The size of the DCR in old parous females was inversely related to the time elapsing since the last litter. It is concluded that in its hormonal requirements for a successful DCR the bank vole is similar to the mouse. The results also suggest that the increase in fertility of bank voles up to the age of about 100 days may in part be explained by increased response of the endometrium to blastocysts. The reduction in size of the DCR in old animals is a consequence of ageing rather than of repeated pregnancies.     

In vitro functions of the rat diaphragm during postnatal development.

This study was designed to determine the developmental changes in the functional characteristics of the rat diaphragm. A total of 150 animals were studied at 1, 3, 5, 7 and 9 weeks of postnatal age. Body and diaphragm muscle weights were measured. Diaphragm strips were studied in an in vitro preparation to assess muscle contractile and endurance properties. Total diaphragm weight increased considerably, by a factor of 23 over the 9 week-period of study and was highly correlated with body weight (r = 0.93, P less than 0.01). However, the ratio of diaphragm-to-body weight decreased progressively with age. In comparison with those from older animals, diaphragms from 1 and 3 weeks old animals: (1) generated similar force normalized for muscle weight but a lower force normalized for fibre cross-sectional area (P less than 0.05), (2) had longer time-to-peak tension and one-half relaxation times (P less than 0.01) and (3) were more resistant to fatigue (P less than 0.01). The mechanisms underlying the diaphragm functional development were discussed.     

Animal age-, dose- and cell line-dependent growth of human neuroblastoma in nude mice. A statistical analysis.

Cells lines from human neuroblastoma (NB) and T/lymphoma (T-L) were injected subcutaneously (sc) in female CD1 nu/nu athymic nude mice. Results obtained after the observation of tumour growth were statistically analyzed by SAS. The following four parameters were considered: 1) dose of injected cells, 2) type of injected tumour (NB or T-L), 3) age of mice after individuation of three groups of animals (group A, 4-9 weeks old, group B, 9-20 weeks old, group C, > 20 weeks old), 4) injected cell line within the same tumour type. Latency time (LT), corresponding to the interval between cell inoculum and the appearance of a 5 mm diameter subcutaneous mass, and survival time (ST), corresponding to the interval between cell inoculum and the appearance of a 20 mm diameter subcutaneous tumour mass, were considered to evaluate tumour growth. Results showed that mass progression is affected by the number of injected cells and both LT and ST are age- and dose-dependent; furthermore, significant differences were recorded by using different NB and T-L cell lines. Group C showed longer LT than other groups; group B animals showed a statistically significant longer ST than groups A and C (p < 0.001). Our results indicate that growth of human NB in athymic mice is faster in young animals, which also show a significantly poorer prognosis, while better ST was observed in old and middle-aged animals. Results show statistically significant differences of both LT and ST in animals differing in age and in animals inoculated with different cell amounts. These results seem not to be related with biological properties of NB cells too, since neither the occurrence of MYCN amplification nor chromosome 1p deletion significantly modified such behaviour.