Mature Age Groups Research Articles

Age and growth of Nephrops norvegicus in the Catalan Sea, using length-frequency analysis

Length-based methods were used to study age and growth of Nephrops norvegicus in the Catalan Sea. The width of the class interval was examined and 1 mm was found most appropriate for the carapace length-based analysis. Two direct methods, Bhattacharya's and Cassie's, and one indirect, ELEFAN I, were used for age determination. Cassie's method was found very subjective and inadequate, while Bhattacharya's and ELEFAN I more effective, easy to apply and more objective. The results of Bhattacharya's method showed the best agreement with those derived from captivity studies; seven age groups were well defined for males and four for females. Mature female age groups were difficult to detect by any method, indicating the effect of reproduction on female growth. Growth parameters of the Von Bertalanffy model and of the seasonally oscillating Von Bertalanffy formula, estimated by FISHPARM and ELEFAN I, were quite close to those derived from captivity studies. ELEFAN I seemed to produce the best results and the Von Bertalanffy model was not found to be superior to its seasonal counterpart, a fact that gives reason for futher studies. Pauly's empirical formula for fish, used for the estimation of instantaneous natural mortality of this species gave reasonable values. The similarity between the results of the present work and those derived from captivity studies, gives support to the potential use of length-based analysis for the estimation of N. norvegicus biological parameters; however, many factors should be taken into account in order to achieve representative samples suitable for length-based analysis.

Effect of cortisol on blood pressure and vascular reactivity in the ovine fetus

The aim of this study was to investigate the cardiovascular effects of exogenous cortisol in fetal sheep, (a) between 100 and 120 days of gestation when cortisol production is minimal and (b) after 130 days when endogenous plasma cortisol starts to rise. Chronically cannulated ovine fetuses (103-120 days, n = 9; 130-137 days, n = 7), received sequentially a 24 h infusion of vehicle (0.9% sodium chloride) and a 24 h infusion of cortisol at 100 micrograms/h. Blood pressure and heart rate changes to bolus injections each of angiotensin II and noradrenaline (0.2, 0.5, 1.0, 2.0 micrograms) were measured before and after the saline and cortisol infusions. Fetuses in each age group, served as additional controls receiving 48 h saline infusions. In both immature and mature age groups, the cortisol infusion increased basal fetal blood cortisol concentrations by 33.7 and 35.4 nmol/l respectively. In the immature group, cortisol, but not saline, caused significant 14.3 and 15.3% increases in basal systolic and diastolic pressures respectively. Basal blood pressure was higher in the mature group, but did not increase further despite the increase in cortisol levels. Furthermore, vascular responsiveness to angiotensin II but not to noradrenaline was significantly enhanced following the cortisol infusion, at both ages. Fetal heart rate did not change following the cortisol infusion. Exogenous cortisol contributes to the regulation of fetal blood pressure in the immature fetus, when other mechanisms have not developed. Cortisol might achieve this, in part, by enhancing vascular sensitivity to angiotensin II.

Energy Consumption Patterns of Mature Australian Consumers

By the year 2001 two out of seven Australians will be aged 50 years or over. While the mature age group growth rate is twice that of the population as a whole, very little is known about this segment in terms of their patterns of buyer behavior. No Australian study has investigated to date energy consumption of mature consumers. This paper explores the over 50 age group in Brisbane, Australia and endeavors to describe and explain the heterogeneity among mature consumers with reference to electricity consumption. As such, this paper demonstrates that mature consumers cannot be simply regarded as a homogeneous group, as has been demonstrated in the United States and Europe but which, to date has not been demonstrated in Australia. Specifically, this paper investigates not only the demographic characteristics, and consumption activities of the over 50 age group in Australia, but also includes energy-specific lifestyle analysis as this complements the demographics and product ownership and use. Through an ana...

Carcass composition and meat quality of brush-tail possums ( Trichosurus vulpecula)

One-hundred-and-thirty-nine possums, balanced as far as possible for sex (68 male, 71 female) and age (1 year, 42; 2–4 years, 61; 5+ years, 36), were slaughtered and the dissected carcass composition, muscle, and cooked meat composition measured. Possums were slaughtered at time in captivity TIC 0 ( n = 58), TIC 14 days ( n = 20) and TIC 28 days ( n = 61). Compared with the 5+ years (mature) age group the 1 year olds (juveniles) were 67% and the 2–4 year olds (immature) 96% of the live weight of the mature possums. Carcass composition was characterised by high lean (78–80%) and low fat (around 1–2%). The cooked meat from possums is very high in protein (∼ 25%) and low in fat, suggesting it should be a valuable source of animal protein with a low total fat, high unsaturated fat content. In all cases cooked meat was rated as tender, based on shear force values, despite having a pH of around 6·3.

Mortality and bacteriology of sepsis following cecal ligation and puncture in aged mice

Epidemiologic data suggest that elderly adults are more susceptible to invasive bacterial infection by indigenous gut flora than are younger adults. The purpose of this investigation was to characterize a murine model of clinically encountered peritonitis in the aged. We subjected three different age groups (young, 16 weeks; mature, 12 months; senescent, 24 months) of C57BL/6NNia mice to surgically induced peritonitis by the cecal ligation and puncture procedure. Senescent mice died in a significantly shorter time following surgery than mature mice (median time to death, 24.4 versus 38.5 h, respectively; P less than or equal to 0.001). Blood, liver, spleen and occasionally, ceca were obtained at 2 and 12 h after the cecal ligation and puncture procedure and immediately following death, to characterize the bacterial kinetics of the model. Qualitative and quantitative aerobic, anaerobic, and coliform cultures were performed. No age-related differences were found in the types of bacteria isolated throughout the time course of progressive sepsis. In mice in the mature and senescent age groups, at 2 and 12 h postsurgery, gram-negative anaerobes and gram-positive aerobes predominated in all tissues that were cultured. At the time of death, however, blood and tissue isolates consisted predominantly of coliform bacteria. The shift from mixed infection during sepsis to predominantly gram-negative bacterial infection reflected a similar progressive shift in bacterial types found in the cecum. At death, senescent mice had 100-fold fewer coliform bacteria in the bloodstream than those found in mature mice (2.5 x 10(9) versus 4.6 x 10(11), respectively). The increased sensitivity of aged mice to invasive bacterial infection documented in this series of experiments accords well with human epidemiologic experience and demonstrates the appropriateness of the model for continued investigations of sepsis in the aged.

Trainability of the Prepubescent Child.

In brief: It is difficult to interpret studies of training-induced physiologic changes in prepubescents because the results may be confounded by the effects of growth and development. Thus studies of this group must carefully equate the training dose and include a control group. The research reviewed in this article indicates that aerobic power, muscle strength, and anaerobic muscle power are trainable. However, the degree of trainability of aerobic power seems somewhat lower in prepubescents than in more mature age-groups. Strength training is recommended for prepubescents only when needed for rehabilitation or for developing well-defined skills; lifting of maximal weights is discouraged.

Costal and crural diaphragm, and intercostal and genioglossal electromyogram activities during spontaneous augmented breaths (sighs) in kittens.

Spontaneously occurring augmented breaths (sighs) are common in infants. The pattern of electrical activity of the inspiratory muscles of the thorax and upper airway during augmented breaths, however, has not been fully characterized in this less than fully mature age group. We therefore examined costal and crural diaphragm and external intercostal and genioglossal EMG activities during spontaneous augmented breaths (n = 46) in 10 anesthetized (1.35% halothane) 1-month-old kittens breathing room air. EMG responses were assessed by comparing the spontaneous augmented breaths (AB) to the five immediately preceding breaths (control). The peak moving time average EMG activity observed during the AB was 240 +/- 32% (mean +/- SD) of control for the costal diaphragm, 279 +/- 66% of control for the crural diaphragm, and 274 +/- 68% of control for the external intercostal muscle. The mean increase in EMG activity during the AB was not significantly different among these three muscle groups (P greater than 0.25). Genioglossal EMG activity during AB was observed in only 1 of 10 study animals. These results document that during AB in anesthetized kittens, activity of the thoracic inspiratory muscles (costal/crural diaphragm and external intercostal muscles) increase in parallel, suggesting that they are modulated in a uniform manner. The infrequent observance of genioglossal activity during AB suggests that either 1) halothane anesthesia depresses genioglossal activity more than diaphragmatic and intercostal activity during AB or 2) that genioglossal recruitment is not necessary to maintain upper airway patency during this period of heightened respiratory drive.

Analysing the Effect of Age Structure on Stock–Recruitment Relationships in Herring (Clupea harengus)

A Leslie matrix model, fit by multivariate time series analysis methods, of the southwest Nova Scotia herring (Clupea harengus) stock indicates that there is feedback from mature stock abundance to recruitment. Median smoothing suggests dome-shaped nonlinearity in this stock–recruitment relationship. Evidence for compensatory density dependence appears most strongly in the relationships of abundances of individual mature age groups and total recruitment. We suggest that this arises from the separation in space and time of spawners based on their size or age. This results in the production of distinct larval cohorts. These cohorts and the spawners which produce them are the units relevant for the examination of density-dependent processes, rather than the total numbers of spawners and recruits.

Impaired conversion of rat uterine estradiol receptors during aging

We have examined the effects of aging on the capacity of rat uterine estradiol receptors to be transformed from 8S to 4S and 5S species. Cytosol receptors from mature (6-month-old) rats or senescent (24-month-old) rats have been exposed to various KCl concentrations, ammonium sulfate precipitation and 25°C heating. Estradiol receptors of both the mature and senescent age groups exist in an 8S form on linear 5–20% sucrose gradients in the absence of KCl and are converted to a 4S molecule in the presence of 0.4 M KCl. At intermediate salt concentrations a greater portion of mature receptors was converted to the 4S species. At 0.15 M KCl 62.3% ± 2.8 of the mature receptors are converted to 4S versus 41% ± 1.9 of the senescent receptors, and at 0.2 M KCl 79.6% ± 3.2 of the mature receptors are converted to the 4S versus 58.2% ± 2.1 of the senescent. Ammonium sulfate treatment in the presence of 0.3 M KCl converted about 80% of the receptors from the 4S to the 5S form, while only about half of the old receptors are affected. When ammonium sulfate precipitates were heated to 25°C all to mature receptors were converted to the 5S species, while only two thirds of the senescent receptors were sedimented at 5S under the same conditions. Inclusion of 20 mM molybdate during preparation blocks conversion of about 15% of the senescent receptors from the 8S to the 4S form but does not affect the mature preparations. Similarly, molybdate treatment does not affect the conversion of the mature estradiol receptors to the 5S form but increases the percentage of senescent receptors remaining in the 4S form from 30 to 45%. Such qualitative differences in receptor conversion may be related to age associated deterioration of estradiol stimulated uterine responsiveness.

Haematology, Plasma Electrolytes and Serum Biochemical Values of Trichosurus Vulpecula (Kerr) (Marsupialia : Phalangeridae).

Effects of age and sex on blood parameters in T. vulpecula were evaluated in pouch and back young, yearlings and mature animals whose ages were estimated. There were age-related changes in haemoglobin concentration, haematocrit, erythrocyte and reticulocyte counts, as well as serum total protein. Sexual dimorphisms were demonstrated in haemoglobin concentration, haematocrit and erythrocyte counts; values for males w.ere greater than those for females in yearling and mature age groups. Among lactating yearling females, those with young >3 months old had reduced body weight, haemoglobin. erythrocyte and serum total protein values. Altered neutrophil : lymphocyte ratios in differential leucocyte counts as well as elevated plasma corticosteroid and glucose values obtained from T. vulpecula in good condition indicated moderate stress associated with the methods of trapping, handling and sampling used. Variable leucocytosis; with relative or absolute neutrophilia; lymphopaenia and eosinopaenia were found in T. vulpecula in poor condition. Haemoconcentration with elevated plasma electrolytes and urea levels were consistent with their dehydrated state. Free corticosteroid levels in plasma from males were higher than those obtained from females.

The adolescent's first pregnancy: a controlled study.

The records of 1,021 primigravida women who delivered single infants from 1973 to 1976 and who were in the adolescent (ages 10-15) and mature (ages 20-24) age groups were reviewed. It was found that the adolescent patient is more often black and unmarried, and has less prenatal care than the mature woman. There was a higher frequency of hypertensive disorders in the adolescents but this was related to race. The adolescent had fewer breech deliveries and more postpartum endometritis and premature deliveries. There was no significant difference in the fetal, neonatal, and perinatal mortality in the adolescent pregnancies.