Long-term observations on the effect of polyadenylic acid in mice of different ages

In order to better life performance, polyadenylic acid (poly (A) ) was given intraperitoneally to CBA/Ca mice for almost a two-year period. This substance, as one of the components of double-stranded polynucleotides (like poly A:U), is known to improve some immune responses of the aging organism. Five approaches (changes in body-weight, adaptation to cold stress, biological half-life of body proteins, mortality and pathology) were applied to test the effects of this substance on life performance. It was found that the beneficial effects of double-stranded polynucleotides cannot be mimicked by polyadenylic acid only, despite its anti-senescence effect, namely, it accelerates the apparent protein turnover, cf., biological half-life. Polyadenylic acid shortens life-expectancy (because of the higher mortality rate of mice). Possible mechanisms of these actions are discussed.

[Chromosome instability in 101/H and C57BL/6 strain mice during aging]

Frequencies of chromosomal aberrations have been shown to increase with the age in the liver cells of 101/H mice. The rate of accumulation is much higher in 101/H than in C54BL/6 mice. The frequencies of mitomycin C-induced chromosomal aberrations in bone marrow cells increased with the age in 101/H mice, but not in C57BL/6. Possible relationships between repair defects and instability of chromosomes in the aged 101/H mice are discussed.

Continuum versus premature aging theories of chronic alcoholism

An attempt is made to differentiate, both theoretically and experimentally, the continuum theory from the premature aging theory of the chronic effects of alcohol on verbal information processing. It is argued that the continuum model necessitates a demonstration of differential 'pattern' of performance between alcoholics and normals in as much as alcoholic Korsakoff patients (at one end of the continuum) do demonstrate such patterns. Premature aging theories, on the other hand, need to demonstrate only subnormal performance by alcoholics relative to their contemporaries. Two experiments designed to assess these theories provided some evidence for premature aging but none for the continuum theory.

[Catecholamines in the myocardium of growing rats after pharmacological sympathectomy]

Examination of the myocardium of 7-, 30-day and 3--5-month-old rats has shown that the content of noradrenaline and adrenaline increased with age. The sympatholytics, reserpine and ornid diminished more markedly the content of catecholamines in the myocardium of 7- and 30-day-old animals. Dopegyt produced a greater catecholamine-reducing effect in 3--5-month-old animals. It is inferred that in the early postnatal ontogenesis, the myocardial response to the sympatholytics is determined by age-associated features of adrenergic control and metabolism.

[Effect of hypotensive preparations on hemodynamics in persons of different sexes and ages]

The relationships between initial parameters of systemic hemodynamics, sex and age and the effect of hypotensive drugs were studied in patients with essential hypertension. It was shown that the ability of clonidine to decrease blood pressure is not related to the patients' sex but depends on their age. The relationship was revealed between the initial parameters of the hemodynamics and the effects of propranolol and oxylidin. No such a relationship was demonstrated as regards the effect of aldomet. The effect of propranolol, aldomet and oxylidin on human circulation has not been found to depend either on sex or age.

[The significance of age dependent organ changes for therapy]

Age dependent physiological alterations of the organs are superposed by pathological changes. The increase of the number of diseases with higher age results in difficulties in drug therapy. As the elderly patients take more medications than younger patients there is an increased incidence of adverse drug reactions in the elderly. Drug elimination occurs principally by two ways: excretion of unchanged drugs by the kidney and of metabolised drugs by the liver and/or kidney. Age dependent changes of these both organs as well as of the stomach and intestine are discussed.

[Role of age in the interaction of tetracycline with the subcellular fractions of rat liver homogenate]

The effect of the rat age on the binding of tetracyclines to the subcellular fractions of liver homogenates was studied. The tetracyclines significantly lost their activity after the contact with the cell organoids. The level of the binding was lower in the newborn and old rats, the complex of tetracycline with mitochondria being less stable. The greater part of the antibiotic reduced its activity after washing of the organoids. The deposition of the antibiotics in the cells was the most pronounced in the pubertal animals.

[Action of hypothyroidism on the metabolic maturation of the pyramidal neurons of the rat hippocampus]

Interference microscopy was used to measure dry mass of pyramidal neurones of hippocampal CA1 and CA3 areas in control and hypothyroid rats aged 14 and 21 days and 2 months. Hypothyrosis was induced in the newborn by intraperitoneal injection of methylthiouracil to the lactating female during the lactation period (for 1 month). Hypothyrosis caused a considerable retardation of the animals' growth. A significant decrease in he concentration of dry substances was detected only in the cytoplasm of Ca1 area neurones in the group of 2-month-old hypothyroid animals. The measurements have demonstrated that hypothyrosis gives rise to pronounced retardation of the neuronal build-up and accumulation of protein products in the cytoplasma of hippocampal pyramidal cells in all the animal groups examined. The size and dry weight of neuronal nuclei of both the hyppocampal areas substantially diminish in the group of 2-month-old hypothyroid animals.

Relationship of growth and puberty in beef heifers fed monensin

An experiment was designed to determine the effects of dietary monensin on age and weight at puberty in Bos taurus crossbred beef heifers. One hundred and forty heifers were allotted to two weight classes: heavy (H) and light (L) groups, consisting of heifers above and below the average weaning weight, respectively. Heifers within each weight class were assigned to one of three diets during a 203-d winter feeding period: (1) R, 80% roughage: 20% concentrate; (2) M1, R diet plus monensin (200 mg/head daily) with feed intake restricted to produce average daily gains (ADG) similar to R and (3) M2, R diet plus monensin (200 mg/head daily). ADG was higher (P less than .001) for M2 heifers than for R and M1 heifers, which performed similarly. Age and weight at puberty were similar across treatments in L heifers. However, in the H group, HM1 and HM2 heifers were younger (P less than .07) at puberty than HR heifers and this difference was not removed by covariate adjustment of either ADG or body weight. Weigh at puberty was greater (P less than .01) for HM2 heifers than for HM1 or HR heifers; however, this difference was removed by covariate adjustment of either ADG or body weight. Ninety-one percent of LM2 heifers and 100% of all other groups had reached puberty before the breeding season. Pregnancy rates did not differ significantly between treatment groups. Supplementation of a high roughage diet with monensin decreased age at puberty of heifers in the heavy weight class and this decrease was not due to increased body weight or ADG. Perhaps heifers with above average weaning weight possess a greater inherent growth potential than heifers below the average weaning weight and hence are more capable of utilizing monensin to an advantage.

[Input-output characteristics of the motor neuron pool during strychninization in dogs of various ages, (an electrophysiological analysis of the occurrence of inhibitory interneurons in postnatal ontogeny)]

In connection with data on the absence of spinal forms of reciprocal inhibition in ante natal and early postnatal periods in puppies, it was decided to use strychninization as a physiological tool which enables to evaluate the onset of the activity of the inhibitory interneurones which are involved into realization of postsynaptic inhibition. Experiments were made on puppies from three age groups (up to 5 days 8--10 days and 20--30 days) in which mono- and polysynaptic reactions to afferent stimulation were recorded. It was established that the onset of the activity of inhibitory interneurones in the developing neuronal system takes place after realization of antigravitational reactions. At the age of 10--30 days, block of postsynaptic inhibition by strychnine returns the spinal cord to that type of reactions which are typical of antenatal and early postnatal periods.

[Effect of hydrocortisone on the formation of osmotic concentration function in white rats]

The age-associated time course of renal concentration function was studied in Wistar rats after a single injection of hydrocortisone (100 micrograms/100 g bw) or physiological saline (the control group) on the 5th day after birth. In the experimental rats aged 20--30 and 60 days, the intrarenal gradients of urea and the osmotic concentration index of the urine (U over P) osm increased, after the test injection of pituitrin P (500 microunits/100 g bw, s. c.), to a less extent than in the control animals. Under dehydration, (U over P) osm in the experimental group was found to be lower than in the controls, whereas the gradients of urea to differ negligibly. It is suggested that hydrocortisone injection in the early postnatal period leads to the decrease in the efficacy of renal concentration function because of changes in ADH reception or in activity of enzymes involved in the reaction to the hormone.

The effect of enzyme therapy on plasma lipid levels in the elderly

(1) An enzyme preparation, Vasolastine, administered intramuscularly, to a group of elderly subjects (mean age 81.7) reduced fasting plasma cholesterol and triglyceride levels by amounts which were proportional to their initial concentration. (2) Triglyceride levels 3 h after a fat-rich meal were also directly dependent on the initial fasting level. This relationship is lowered significantly after 25 days of Vasolastine treatment. (3) It is suggested that these observations, taken in conjunction with the results of in vitro studies, confirm that Vasolastine acts synergistically with endogenous lipoprotein lipase.

[Development in ontogeny of the effect of ACTH fragment 4-7 on rat learning]

Studies have been made of the effect of ACTH fragment 4-7 on learning in rats in early postnatal ontogenesis, as well as of the possibility of preservation of early learning during administration of this peptide to adult animals. It was shown that conditioned reaction of active avoidance practically cannot be formed in normal 13-15-day animals; however, administration of ACTH 4-7 increases the number of animals exhibiting adequate reactions. Weak effect of ACTH 4-7 in 12-15-day animals, in older ones (20-24 days) is changed by a significant stimulating effect.

Gentamicin pharmacokinetics: effect of aging in patients with normal renal function

The effects of aging on gentamicin total-body clearance, volume of distribution, and half-life were examined in 173 febrile patients with gram-negative infections. All had normal renal function, normal hematocrit levels, near-ideal body weights, and were not receiving concurrent penicillin therapy. In the 51 patients who were 20-39 years old, the mean clearance of gentamicin was 1.29 ml/min/kg, the volume of distribution was 0.23 l/kg, and the half-life was 2.2 hours. In the 59 patients 40-59 years old, these values were 1.35 ml/min/kg, 0.27 l/kg, and 2.1 hours; in the 63 patients 60-79 years old, they were 1.31 ml/min/kg, 0.26, and 2.4 hours. No significant difference was observed for any of the measures among the three age groups (P less than 0.05, analysis of variance). Linear regression revealed poor correlations between the individual measures and age. Since there is no change in gentamicin pharmacokinetics with aging, dosages do not need to be changed arbitrarily for older patients who have normal renal function.

The menopause

Hormone-replacement therapy for postmenopausal women has associated benefits and risks. The advantages of the administration of estrogen to postmenopausal women include preventing or reversing the atrophic changes of the genitourinary system, slowing of facial aging, relieving hot flushes and psychological symptoms, preventing atherosclerotic heart disease and retarding the development of osteoporosis. The disadvantages of the administration of estrogen to postmenopausal women include rare but serious clinical sequelae associated with the ingestion of the synthetic estrogen when it is one component of the combination oral contraceptives, increased risk of cancer developing in the estrogen-dependent organs and uterine bleeding. The benefits of long-term cyclic estrogen-gestagen therapy in preventing osteoporosis far outweigh the risks.