Tissue-specificity of reactivity to concanavalin-A of human cells in culture

Concanavalin-A (Con-A) reactivity was studied to identify the tissue-specificity of cells established from various normal human tissues. Cells were treated with Con-A-labelled human red blood cells (C-RBC). C-RBC was not absorbed on the cells derived from the bone marrow, skin and liver. Lung-derived fibroblast cells showed weak C-RBC adsorption. Kidney-derived cells showed epithelial morphology and easily adsorbed C-RBC. These suggest that a large number of Con-A receptors exists on the membrane surface of kidney cells.     

Phospholipid metabolism in livers of young and old fisher 344 and Sprague-Dawley rats

The levels and fatty acid spectra of liver phosphatidyl choline, phosphatidyl ethanolamine, phosphatidyl serine, phosphatidyl inositol, lysophosphatidyl choline and sphingomyelin were compared in 3-, 12- and 18-month-old Fisher 344 and Sprague-Dawley rats. Levels of phosphatidyl choline, phosphatidyl serine plus inositol and phosphatidyl ethanolamine were significantly higher in livers of Sprague-Dawley rats. Although there were strain-related differences in phospholipids, there were no age-related differences. The ratio of polyunsaturated/saturated fatty acids was higher in the phospholipids of young Fisher 344 rats. Choline kinase activity was (20–40%) higher in the livers of Fisher 344 rats, but activities of sphingomyelinase and of dihydrosphingosine biosynthesis were not significantly different from those of Sprague-Dawley rats.     

Brain catecholamine content and turnover in aging rats

The content and turnover of catecholamines were evaluated in various brain regions of young adult (4-months) and aged (24-months) male rats. Turnover was assessed from the concentrations of acid metabolites and the decline of catecholamine content after synthesis blockade with alpha-methyl-p-tyrosine. Dopamine was reduced by aging in striatum, mesolimbic areas, and hypothalamus. Dopamine metabolites and turnover rate were significantly lower in striatum and mesolimbic areas of aged than of young animals. Hypothalamic norepinephrine content and turnover rate were unchanged in aged compared to young rats but its metabolite (MHPG-SO4) was increased in the cortex. These findings point to an extensive impairment of brain dopamine metabolism in aging rats, whereas norepinephrine seems to be less impaired.     

Effect of inhibitors and stimulators on isolated liver cell mitochondrial protein synthesis from young and old rats

Mitochondria isolated from the livers of old rats (26–30 months) were found to incorporate 41% less leucine into mitochondrial proteins as compared to those from young rats (2–3 months). The initial rates of incorporation of label were 145 cpm/mg/min for the “old” animals, and 320 cpm/mg/min for the young animal. No difference in either amino acid pool size or leakage of label through the mitochondrial membrane was detected in the two age groups. Young rats were treated in vivo with cycloheximide (10 mg/kg) followed by isolation and incubation of their mitochondria in vitro two hours later. There was a two-fold increase in incorporation of leucine into mitochondrial proteins. In contrast, mitochondria isolated from old rats showed a markedly blunted response to cycloheximide pre-treatment. When mitochondria isolated from young and old rats were exposed to inhibitors of mitochondrial protein synthesis, --dipyridyl (2 × 10⁻⁴M) and ethanol (0.15M), the old mitochondria showed greater susceptibility to inhibition. These results suggest that the control of the biosynthesis of mitochondrial proteins is altered in the old animals.     

Biological age and its estimation. II. Assessment of biological age of albino rats by multiple regression analysis

Multiple regression model of biological age (BA) theoretically gives agreement with the main concept of BA. When assessment of BA is based on the model, the age being in regression center, the method provides satisfactory results, whereas BA estimates of individuals in extreme age groups are erroneous. Investigation of male and female Wistar rats of age 5–29 months showed the BA estimates calculated from 4–10 physiological indices in young (5–7 mo) animals are overestimated, and in old (24–28 mo) animals are underestimated. Coincidence of average BA in one-age group of animals with its chronological age served as a criterion for the correspondence of the estimate to “real” BA. The paper also examines the following questions: the necessary and sufficient number of physiological indices; the sample size from the intact animal population to establish normal aging standard; the relationship between BA and animal weight.     

The effects of proteins upon the filtration coefficient of individually perfused frog mesenteric capillaries.

The filtration coefficients (L_p) of the walls of individually perfused frog mesenteric capillaries have been measured using the methods described by Michel et al. (1974). When a vessel was perfused with frog Ringer solution containing no protein, L_p was four to five times greater than its value for the same capillary perfused with frog plasma. The increase of L_p seen on perfusion with protein-free solutions was readily reversible and could be prevented by adding to the Ringer perfusate bovine serum albumin, bovine γ-globulin and human haemoglobin. The addition of whale myoglobin (0.5 g 100 ml^?1) to the Ringer perfusate did not prevent an increase in L_p. Ringer solutions containing 0.1 g of bovine serum albumin 100 ml^?1 were as effective as those containing higher concentrations of albumin in preventing the increase in L_p, but the L_p of capillaries perfused with solutions containing 0.01 g of albumin 100 ml^?1 did not differ from the values for the same capillaries perfused with protein-free solutions. It was shown that in any given capillary, L_p was independent of the direction of fluid flow across the vessel wall and was the same when the capillary was perfused with 9.0 g of bovine albumin 100 ml^?1 and 3 g of bovine γ-globulin 100 ml^?1. Whereas the effects of L_p are seen within 1 min of removing the protein from the perfusate, no changes in L_p were observed during the first 20 min of perfusion and superfusion of capillaries with solutions free of Ca²⁺ and Mg²⁺. L_p also appeared to be unaffected after 20 min perfusion with neuraminidase. It is suggested that plasma proteins are adsorbed onto capillary walls and greatly modify capillary permeability.     

Antigenic determinants on lymphocytes from young and old C57BL/6 mice

Antigenic differences between lymphocytes from young and old female C57BL/6 mice were studied using 3 techniques. In one-way mixed lymphocyte reactions significant responses were obtained in 7.7% of the young leads to young combinations, 13.5% of the young leads to old, 18.2% of the old leads to young and 23.7% of the old leads to old. Polyethylene glycol enhanced the weak syngeneic MLR responses in all groups. Young anti-old antiserum was raised in young animals by injecting with lymphoid cells from old mice. The serum was cytotoxic to spleen cells from 5 of 6 old mice aged in animal facilities at University of Alabama in Birmingham and from 2 of 12 mice aged at Charles River. Lymphocytes from young mice were sensitized to old lymphocytes in a mixed lymphocyte culture and their cytotoxicity toward old cells measured in a chromium-release assay. No cytotoxicity was observed with sensitized lymphocytes from 5 young mice under various conditions. These results do not support the hypothesis that altered anti-genic determinants are always or even usually present on the lymphocytes of old mice.     

Food intake reduction and immunologic alterations in mice fed dehydroepiandrosterone

A diet containing 0.4% DHEA was fed to male mice of a long-lived strain from 3 weeks until 18 weeks of age. These mice were compared with others fed a control diet ad libitum and with mice pair-fed the control diet in amounts approximating the intake of the DHEA-fed group. Mice fed the DHEA diet failed to eat all of food presented to them whereas the pair-fed mice ate all of their food. All mice were studied at 18 weeks of age for twp age-sensitive immune parameters (spleen lymphocyte proliferation induced by T-cell mitogens [PHA or ConA] and natural killer cell lysis of an allogeneic tumor). DHEA feeding led to: 1) a decrease in food intake ( ～30% less than for mice fed the control diet ad libitum), 2) a lower body weight at 18 weeks of age ( ～40% lower than for ad libitum controls) due to a decrease in the body weight gained from 3 weeks through 18 weeks of age ( ～55% lower than controls), 3) a lower spleen weight ( ～30% lower than controls) but without lower numbers of nucleated cells per spleen, 4) an increase in PHA-induced proliferation by spleen lymphocytes ( ～100% higher than for controls) and, 5) no influence on splenic natural killer cell activity. The inhibition of body weight gain for mice fed DHEA appeared due to both a reduction in food intake and a metabolic effect since mice eating DHEA gained less body weight per gram of food eaten than did mice in eithergroup eating the control diet.     

The effects of cationised ferritin and native ferritin upon the filtration coefficient of single frog capillaries. Evidence that proteins in the endothelial cell coat influence permeability

To investigate whether certain macromolecules reduce capillary permeability by binding to the surface coat of endothelial cells, the effects of cationised ferritin (CF) upon the filtration coefficient (L_p) of individually perfused frog mesenteric capillaries were compared with those of native ferritin (NF). With perfusate CF concentrations between 0.1 g 100 ml^?1 and 2.5 g 100 ml^?1, L_p was reduced to approximately 30% of its value for the same vessel perfused with protein-free Ringer solution. Electron micrographs of the perfused capillaries revealed that over this range of perfusate concentrations, CF was concentrated uniformly in the endothelial cell coat, occupying 8.5% of its volume. Neither the effect of cationised ferritin upon L_p nor its concentration in the cell coat varied significantly over this range of perfusate concentrations. When perfusate concentration of CF was reduced to 0.01 g 100 ml^?1, CF no longer reduced L_p and its concentration in the cell coat fell below 2%. Native ferritin, which is excluded from the cell coat, did not reduce L_p at a perfusate concentration of 0.1 g 100 ml^?1. At a concentration of 2.5 g 100 ml^?1, NF reduced L_p in a few very permeable vessels (L_p > 60 × 10^?3μm sec^?1 cm H₂O^?1) but had no significant effect on vessels with lower and more normal values of L_p. The effects of CF upon L_p can be described in terms of the Kozeny equation if a major proportion of the hydraulic resistance through the capillary wall is attributed to a fiber protein matrix.     

Secretion of α-amylase from parotid lobules of young and old rats

The rate of release of a secretory enzyme, α-amylase, from the parotid lobules of 2 and 24 month old rats has been compared to determine whether the secretory activity of the cells change during aging. Upon incubation in the presence of a secretogogue, isoproterenol (10^?5 M), about the same proportions of the glandular α-amylase are released at about the same rate from these lobules. The isoproterenol-stimulated release of the enzyme is inhibited nearly completely by preincubating the lobules with propranolol (10^?5 M) in both age groups, indicating that the enzyme secretion occurs through the stimulation of β-receptors. When viewed in the electron microscope, the cell membranes bordering the secretory lumen in isoproterenol-incubated lobules reveal festooned appearances which suggest that the enzyme release occurs by means of exocytosis. These observations indicate that the ability of the parotid cells to release secretory products through the β-receptor mediation does not significantly change with increasing age.     

Testicular development and testosterone concentrations in the testis and plasma of young male shrews (Suncus murinus)

Testicular development and testosterone concentrations in the peripheral plasma and testes of young, adult, and castrated male musk shrews (Suncus murinus) were examined. Fifty immature, 24 adult, and eight castrated males were used. Immature males ranged from 5–45 days of age. Plasma and testis homogenates were assayed for testosterone by radioimmunoassay. Testes were examined histologically for spermatogenic development. Plasma testosterone concentrations increased gradually from Day 5 to Day 24, then rapidly to Day 30. There was a sharp decrease between Day 30 and 33, then a gradual increase to Day 45. Testis testosterone concentrations followed the same pattern, except that on Day 5, the concentration was significantly higher than on Day 10. Adult males had higher testis testosterone and lower plasma testosterone concentrations than Day 45 males. Castrated males had barely detectable plasma testosterone levels. Testis weights increased linearly with age, except for a slight decrease between Day 30 and 33. Spermatogenic development was already initiated by Day 5. Cap-phase spermatids were present on Day 23, acrosome-phase spermatids on Day 30, and mature spermatozoa on Day 31. Epididymal sperm were present by Day 45.     

Changes of vasopressin- and oxytocin-immunoreactive neurons after hypophysectomy in young and old mice

Changes of magnocellular neurons after hypophysectomy were immunohistochemically studied using antisera to arginine vasopressin (AVP) and oxytocin (OXT) in young and old female mice of the C57BL/Tw strain. AVP-immunoreactive neurons in the supraoptic and paraventricular nuclei of intact 19-month-old mice showed a marked reduction in number and immunoreactivity as compared with those of intact 3-month-old mice. Age difference of OXT-immunoreactive neurons was less pronounced than that of AVP-immunoreactive neurons. After hypophysectomy, both AVP- and OXT-immunoreactive neurons showed an intense stainability 10 days after the operation regardless of ages. However, the rate of reduction in number of immunoreactive neurons after hypophysectomy was less marked in 19-month-old than 3-month-old mice.     

Biological and chemical properties of chincilla pituitary prolactin

Previous work (J. E. Platt and M. A. Christopher, 1977, Gen. Comp. Endocrinol., 31, 243–248) had shown that a single injection of ovine prolactin (PRL) given to larval or neotenic tiger salamanders retarded tail fin regression induced in these animals with thyroxine (T₄). This antagonism of T₄-induced tail fin regression was correlated with PRL-induced changes in the water and sodium content of tail tissue. The present study presents evidence which demonstrates that the alternation of tail water and sodium levels occurs well within the normal lag period that precedes the morphological manifestations of T₄-induced tail fin regression. Additional experiments using a simple in vitro incubation system show that larval tail skin pieces maintained in this system increase their water content when incubated for 22 hr with PRL. Incubation of tail skin pieces taken from recently metamorphosed animals under identical conditions does not reveal a response to PRL. Further, untreated larval tail skin maintains a significantly higher water content than untreated tail skin from metamorphosed animals incubated for the same time in vitro. These results are discussed with regard to the mechanism whereby PRL acts to block T₄-induced tissue differentiation in amphibians.     

Accelerated aging of fasted Drosophila Preservation of Physiological function and cellular fine structure by thiazolidine carboxylic acid (TCA)

Thizalidine carboxylic acid (TCA) is a natural liver metabilite whose M_g-salt increased lifespan of flies and mice (Miquel and Economics, 1979, Exp. Geront.14: 279). We studied the physiological and cellular fine structural effects of various concentrations of TCA in the food of male Drosophila. Flies on 0.3% TCA at 27°C had a reduced oxygen consumption rate (about 20% less than controls) at 3 eks of age while their mating capacity and speed of mating were preserved; the flies lived in various experiments 20–30% longer than controls. Apparently TCA improved the metabolic efficiency of the flies (possibly from less “waste” of energy due to improved mitochondrial coupling). However, flies on 0.9% TCA had a reduced mating capacity and lifespan (:toxicity) while at 0.1% TCA was ineffective. A similar dose-response relationship was found in young flies treated with TCA for 1 week and then deprived of food and water, a procedure found to induce accelerated physiological aging. TCA at the 0.3% and 0.6% level reduced the speed of development and the size of the eclosed flies. Electron microscopic investigation of wing muscle showed that 0.3% TCA had a protective effect on cellular fine structure. Though in starved controls (40% survivors after 25 hours of starvation) there was a total absence of glucogen granules, and a striking and densification of mitochondria, TCA to a large extent protected muscle cells from these effects of starvation.     

The effect of dietary restriction on cell division potential, DNA content and enzyme levels in the rotifier Asplanchna brightwwelli

Dietary restriction in the rotifer Asplanchna brightwelli, carried out by lengthening the interval between feedings, causes an increase both in mean lifespan and in the length of the reproductive period. In the present study, we found that the rate of nuclear division in the gastric glands and vitellarium of the rotifer, as determined by daily nuclear counts, was retarded by dietary restriction. Spectro-fluorimetric measurements show that total DNA content remains constant from the beginning to the end of the lifespan, and is unaffected by dietary restriction. Lactic dehydrogenase and malic dehydrogenase activities were also measured throughout the lifespan of the rotifer, and were not affected by dietary restriction.     

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.     

Physiological response to postural change during mild hypoglycaemia in patients with IDDM

Summary It has been suggested that patients with insulin-dependent diabetes mellitus may be less aware of impending hypoglycaemia when lying than standing. We have studied the effect of posture and duration of hypoglycaemia on symptoms and physiological responses in 10 men with insulin-dependent diabetes. A standard tilting protocol was used (supine, 50, 90 headup, and return to supine, 5 min at each position). At one visit patients were tilted before, 10 min after and 40 min after achieving hypoglycaemia (blood glucose 2.5 mmol/l), and at another visit were tilted after euglycaemia (5.0 mmol/l) using a hyperinsulinaemic clamp. At each position, hormonal and physiological responses and symptoms (using visual analogue scales) were recorded. After 10 min of hypoglycaemia, adrenaline was significantly higher when 90 headup compared with supine (mean [±SEM] 6.26 [±1.88] vs 1.68 [±0.4] nmol/l; p<0.05), and fell significantly (to 2.46 [±0.65] nmol/l; p<0.05) when returned to supine; sweating, symptom score and blood pressure followed a similar pattern. After 40 min of hypoglycaemia a similar effect of standing was seen on sweating, adrenaline and blood pressure but symptoms did not increase. Five patients underwent two further periods of hypoglycaemia, remaining supine or standing throughout. Face skin blood flow (p<0.05) and temperature (p=0.05) decreased when standing was maintained compared with lying. In conclusion, standing increases awareness of early hypoglycaemia and modifies many of the physiological changes. This increase in awareness is lost if hypoglycaemia is prolonged.Abbreviations IDDM Insulin-dependent diabetes mellitus - ANOVA analysis of variance - bpm beats per min     

Adrenocortical responses to novel stressors in acutely or repeatedly starved chickens

The effect of starvation on the corticosterone responses of immature cockerels to acute, novel stress has been determined. The marked corticosterone responses of fed birds to either horizontal treadmill exercise (0.04 km/hr) or intravenous adrenocorticotrophic hormone (ACTH) administration (P less than 0.001 in both cases) were reduced by starvation (P less than 0.01 and P less than 0.001, respectively). This reduction did not appear to be due to either feedback inhibition of corticosterone on the hypothalamus or pituitary, or to reduced adrenal responsiveness to endogenous ACTH. Starvation significantly elevated the basal level of circulating corticosterone (P less than 0.001), but the magnitude of this elevation and the level of corticosterone attained were less (P less than 0.05) in birds that were accustomed to starvation. This habituation of adrenocortical activity may be due to reduced pituitary ACTH secretion, and was specific in that the corticosterone responses to novel stressors were unaffected.