Basal and stimulated calcitonin secretion in primary hyperparathyroidism before and after parathyroidectomy

To investigate calcitonin secretion in primary hyperparathyroidism, basal and stimulated (3 mg Ca++/kg body weight/10 min) immunoreactive calcitonin plasma levels were studied before parathyroidectomy. Plasma calcitonin levels were raised in 50% of patients regardless of sex, but a significant correlation between basal plasma calcium and calcitonin was found only in males. A reduced calcitonin response to calcium infusion was observed in all patients. Parathyroidectomy invariably induced a normalization of calcitonin basal levels. Our findings confirm the existence of a decreased parafollicular cell reserve probably as a consequence of the persistent hypercalcemic state in hyperparathyroid patients and suggest that it is more frequent in females.     

Isolated hypothalami from aging female rats do not exhibit reduced basal or potassium-stimulated secretion of luteinizing hormone-releasing hormone.

Serum LH levels are diminished in middle-aged rats during spontaneous or steroid-induced LH surges and following ovariectomy (ovx). The compromised LH responses are presumed to reflect age-related alterations in LHRH neurosecretion. Direct measurements of LHRH output in middle-aged females are, however, limited. The present study utilizes an in vitro perifusion paradigm to assess basal and stimulated secretory capacity of LHRH neurons in isolated hypothalamic preparations from aging female rats. Individual hypothalamic fragments from middle-aged and young proestrous, ovx, and ovx, estradiol-treated females were perifused for 6 h and effluents were collected continuously at 10-min intervals. After 4 h of unstimulated output, two 10-min depolarizing pulses of KCl were administered. Although stimulated LHRH secretion was comparable in the two age groups, basal LHRH release from aging hypothalami was significantly elevated (pbasal less than 0.001). Furthermore, endocrine influences on LHRH output from aging hypothalami were less pronounced when compared to endocrine influences on LHRH output from young hypothalami, suggesting that steroidal regulation of LHRH secretion may be impaired in middle-aged females. These data demonstrate that LHRH neurons maintain the capacity to respond to a depolarizing stimulus at the time when regular estrous cycles cease and consequently suggest the importance of altered modulation of LHRH neurosecretion to the development of reproductive senescence.     

Plasma immunoreactive calcitonin in the frog (Rana pipiens)

1. Plasma immunoreactive calcitonin (iCT) and ionic calcium [( Ca]i) were measured in intact frogs (Rana pipiens) within complete 24 hr light-dark cycles over an 18 month period. 2. Plasma iCT exhibits an annual periodicity about the annual mean of 10.0 ng/ml, with an amplitude of 5.4 ng/ml that peaks in October. 3. Within an annual cycle, a significant inverse association exists between the basal monthly levels of plasma iCT and [Ca]i for animals maintained in freshwater control conditions. 4. When subjected to a high calcium environment during the latter half of the year, plasma [Ca]i and iCT were elevated above control levels but exhibited independent cyclic patterns. 5. A distinct seasonal response of increased iCT in a high calcium environment may be related to the secretory activity of the ultimobranchial glands and physiological responsiveness to other calcemic hormones; e.g. parathyroid hormone and vitamin D.     

The cortisol response to ACTH in pigs,heritability and influence of corticosteroid-binding globulin

In the search for biological basis of robustness, this study aimed (i) at the determination of the heritability of the cortisol response to ACTH in juvenile pigs, using restricted maximum likelihood methodology applied to a multiple trait animal model, and (ii) at the study of the relationships between basal and stimulated cortisol levels with corticosteroid-binding globulin (CBG), IGF-I and haptoglobin, all important players in glucose metabolism and production traits. At 6 weeks of age, 298 intact male and female piglets from 30 litters (30 dams and 30 boars) were injected with 250 µg ACTH(1–24) (Synacthen). Blood was taken before ACTH injection to measure basal levels of cortisol, glucose, CBG, IGF-I and haptoglobin, and 60 min later to measure stimulated cortisol levels and glucose. Cortisol increased 2.8-fold after ACTH injection, with a high correlation between basal and stimulated levels (phenotypic correlation, r_p=0.539; genetic correlation, r_g=0.938). Post-ACTH cortisol levels were highly heritable (h²=0.684) and could therefore be used for genetic selection of animals with a more reactive hypothalamic–pituitary–adrenocortical axis. CBG binding capacity correlated with cortisol levels measured in basal conditions in males only. No correlation was found between CBG binding capacity and post-ACTH cortisol levels. Basal IGF-I concentration was positively correlated with BW at birth and weaning, and showed a high correlation with CBG binding capacity with a strong sexual dimorphism, the correlation being much higher in males than in females. Basal haptoglobin concentrations were negatively correlated with CBG binding capacity and IGF-I concentrations. Complex relationships were also found between circulating glucose levels and these different variables that have been shown to be related to glucose resistance in humans. These data are therefore valuable for the genetic selection of animals to explore the consequences on production and robustness traits, but also point at pigs as a relevant model to explore the underlying mechanisms of the metabolic syndrome including the contribution of genetic factors.     

Serum Iron and Iron-Binding Capacity in Normal Subjects

Normal values for serum iron and unsaturated iron-binding capacity of serum were established in a carefully selected group of control subjects by a modification of the procedure described by Schade and coworkers. No significant difference was found between mean values in males and females, and there was no correlation between serum iron levels and age in adults. The value of serum iron as a diagnostic aid is limited by the wide range in normal subjects and the large variation that occurs in the same individual from hour to hour and day to day.     

Body mass, age and sexual maturity in short-beaked echidnas, Tachyglossus aculeatus

During the course of this 12 year field study body masses of 11 hatchling echidnas (Tachyglossus aculeatus multiaculeatus) and 25 pouch young between the ages of 5 and 60 days were recorded. Body mass increased from 0.3 to approximately 50 g in the first half of pouch life. It then quadrupled before young were placed in a burrow at 45 to 55 days of age. There was a positive correlation between the body mass of the female and that of her young at weaning. From 33 subadult echidnas located, tagged and radio tracked during this study, body masses of 10 were monitored to sexual maturity, i.e. when first encountered in a courtship train. Minimum age of sexual maturity ranged between 5 and 12 years. As subadults, there was no difference between mean body masses of males and females. At sexual maturity, mean body mass of females was significantly higher. No correlation was found between age at sexual maturity and body mass nor was there a significant difference in age of males and females at sexual maturity.     

The role of estrogen in the TSH and prolactin responses to thyrotropin-releasing hormone in postmenopausal as compared to premenopausal women.

The basal and TRH (Thyrotropin-Releasing Hormone) stimulated TSH (Thyrotropin) and PRL (Prolactin) responses (incremental area; IA) to 200 micrograms TRH was studied in 13 pre- and 13 postmenopausal women of 60 years of age. Both groups consisted of healthy women, none had goiter and all were negative for thyroid autoantibodies. The serum levels of TSH, T3, T4 and SHBG (sex hormone-binding globuline) were in the normal range and did not differ significantly between the groups. There were no differences in basal TSH (1.3 +/- 0.5 vs 1.4 +/- 0.5 mIU/l) or PRL (6.4 +/- 2.7 vs 6.6 +/- 2.5 micrograms/l) or for PRL IA (498 +/- 126 vs 584 +/- 165) between pre- and postmenopausal women. However, for TSH IA there was a slight decrease (15%), but not significant, in the postmenopausal group compared to the premenopausal group (1630 +/- 598 vs 2067 +/- 893). In conclusion, a weak but not significant decrease in the TSH response to TRH in postmenopausal women may be explained by the lower endogenous estradiol level.     

Age-related determination of the basal and calmodulin-stimulated human RBC Ca2(+)-ATPase activity

The basal and calmodulin-stimulated activity of the human erythrocyte Ca2(+)-ATPase was determined in 56 healthy individuals of different ages in order to set control values. The basal activity of all 56 healthy subjects was 0.805 +/- 0.525 mumole hydrolyzed ATP/mg protein/hr, while the calmodulin-stimulated activity gave an average of 2.437 +/- 0.785 mumole hydrolyzed ATP/mg protein/hr. There was no significant difference in basal Ca2(+)-ATPase activity in males and females; however, significantly increased levels of the stimulated red cell calcium pump was seen in females. Based on age, the basal activity for newborns and children up the age of 7 years was higher than that for adults and a distinct increase in activation by calmodulin was observed with a maximum at the age range of 8-13 years. It was demonstrated that for the investigation of Ca2(+)-ATPase activities in children different normal values must be taken into consideration than for those already reported for adults. Our data may serve as controls for Ca2(+)-ATPase activities for comparison purposes and for further studies from different diseases in childhood where increased intraerythrocytic calcium levels are reported.     

Electrophysiological investigations of sex pheromone reception and release in Bruchidius atrolineatus

ABSTRACT. Male antennal sensitivity to female sex pheromone in Bruchidius atrolineatus was investigated electrophysiologically (EAG). The existence of receptors for this pheromone was shown in the antennae of males. (No such receptors exist in the antennae of females.) Young (age < 24h) males gave an EAG of amplitude 25–30% of the response of older males. Diapausing males several days old gave a much smaller response than active males of the same age.
EAGs were used to test the production/release of pheromone by groups of twenty females. Before they are 24 h old, active females do not produce/release the pheromone; older females release it at an almost constant rate. Sexually diapausing females do not produce and/or release the sex pheromone.
In sexually active females, mating inhibits pheromone release almost immediately. There is a correlation between reproductive status of the females (development of ovaries, oogenesis) and the production or release of the pheromone. A corresponding correlation also exists in the males whose antennae show a very low sensitivity when they are young or when they are in reproductive diapause.     

Gender differences in the echocardiographic characteristics of the athletic heart

Differences between males and females in the effects of regular physical training on the heart were investigated by echocardiography in 579 male (nonathletes: 122, athletes: 457) and in 336 (nonathletes: 84, athletes: 252) female subjects of variable age. The age groups were: children (<15 yr.), adolescent-young (15-18 yr.), young adult (19-30 yr.), adult (31-45 yr.) and people elder than 45 yr older (45<). Hypertrophy characterised by relative left ventricular muscle mass (rel.LVMM) of the athletic heart was manifest also in the females, but in comparison with the males female values were much lower both in the unconditioned and in the conditioned groups. In people belonging to the oldest groups no differences were seen either between the males and females or between athletes and nonathletes. In comparing nonathletic subjects, females showed smaller left ventricular contractility as reflected by a higher LVET/QT ratio and an increased ability of diastolic relaxation as indicated by a higher E/A ratio. Physical training induced a more marked development when the initial level was lower, namely, in the contractility of the females, and in the compliance of the males. No intersex difference was seen in the modified regulation of the athletic heart, characterised by a lower resting heart rate and slower circumferential shortening velocity (VCF).     

The concentration of twelve elements in the anterior pituitary from human subjects and rats as measured by particle induced X-ray emission (PIXE)

The concentration of twelve elements—potassium, calcium, manganese, iron, cobalt, nickel, copper, zinc, arsenic, selenium, bromine, and rubidium—in anterior pituitaries from human subjects and rats was measured using Particle Induced X-ray Emission (PIXE). The human material included anterior pituitaries from 37 normal human subjects, 27 males and 10 females, all of whom died from traumatic lesions. Excluded from the investigations were persons with alcohol abuse, regular use of drugs, and babies younger than 1 year. For selenium, zinc, bromine, and to some extent copper, there was good correlation between the amounts found in anterior pituitaries from rats and human subjects. A significant difference between male and female rat pituitaries was observed for copper, iron, and rubidium, whereas for humans significant difference was only observed for manganese. Anterior pituitaries from human females contained generally more zinc than male glands, but the concentration of zinc in young males was higher than in females. The present study also indicates age related differences in the copper content in anterior pituitaries from human subjects, since pituitaries from humans between 15–45 years contained 25% more copper than those from younger or older persons. The opposite pattern was observed in males. For such elements as Cu, Fe, Mn, and Se, the content in the anterior pituitary from human subjects was 1.6–2 times that stated for other endocrine organs.     

Distinct Associations between Hypertension and Obstructive Sleep Apnea in Male and Female Patients

Obstructive sleep apnea (OSA) is highly associated with hypertension. However, the correlation between hypertension and OSA at different levels of severity and the influence of gender on that correlation are unclear. A total of 996 patients (776 males and 190 females) with OSA were recruited. The influence of gender on the correlation between hypertension and OSA at different stratifications of severity, based on the apnea-hypopnea index (AHI), was fully evaluated together with the major health risk factors obesity, age, and diabetes. Females with OSA were significantly older on average than males with OSA. Moreover, females had milder degrees of OSA on average than the extent of severity seen in males. The proportion of females with diabetes or hypertension was higher than that of males. The proportion of males with hypertension and obesity increased significantly with OSA, and age also increased with OSA. The percentage of females with hypertension at different degrees of OSA severity was stable at about 26% in the mild, moderate, and severe OSA groups. Among females, age was increased significantly in the moderate relative to the mild OSA group. Moreover, the proportion of obese subjects was increased significantly in the severe compared with the moderate OSA group. The proportions of males and females with diabetes were not significantly different among all OSA severity groups. An ordinal multivariate logistic regression analysis confirmed that hypertension, age, and obesity were associated with OSA severity in males, whereas only age and obesity were associated with OSA severity in females. Although the proportion of subjects with hypertension was higher in females with OSA than in males with OSA, the proportion of subjects with hypertension increased as the severity of OSA increased in males but not in females.     

Beta adrenergic receptors and cyclic AMP levels in intact human lymphocytes: Effects of age and gender

A saturable, stereospecific high affinity beta₂ adrenergic receptor was demonstrated on intact human peripheral blood lymphocytes using the ligand [¹²⁵I]-iodocyanopindolol ([¹²⁵I]ICYP). A method is described for parallel measurements of saturation binding isotherms and isoproterenol-cAMP responsiveness in split samples of intact lymphocytes isolated from 40 ml. of whole blood. A significant positive correlation between beta receptor density (Bmax) and the ratio of maximal isoproterenol-generated cAMP to basal levels was found in healthy subjects (r=0.65, p < 0.001). A significant positive correlation was found between age and the fold increase over basal cAMP levels induced by isoproterenol. Older females had a significantly higher fold increase in cAMP levels after isoproterenol than older males. These effects were largely accounted for by the lower basal levels of cAMP in older subjects. Beta receptor binding indices (Bmax and K_D) did not differ between males and females, or change with aging. The effects of age and sex upon cAMP levels appear to be at least partly mediated by mechanisms independent of the beta receptor. The method, which describes a convenient assay for parallel measurement of beta receptor binding and cAMP levels in small blood samples, represents a useful model for studying human beta receptor function.     

Hypertension, and blood pressure response to graded exercise in young obese and non-athlethic Nigerian university students.

Hypertension, and the effect of graded exercise on Blood pressure (BP), in 60 obese non-athletic young medical students (40 females and 20 males) with Body Mass Index (BMI) greater than 30 were studied. The subjects were in the age range of 18-22 years with mean age of 20.30 +/-1.32 years. Twenty percent of the males and 7 percent of the females were found to be hypertensives [P < 0.05] and the severity of the hypertension significantly [P < 0.05] increased linearly with increase in BMI (r =0.6). Our study reveals a positive direct correlation between obesity and socioeconomic status and BP. Marked increases in systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), time of return (RT) were observed in the obese individuals compared to control at all levels of graded exercise with the highest rises seen during severe exercise. Among the obese subjects, the increases in BP were more in the males than females, but time of return was higher in females than males. This study further confirms that obese young individuals are prone to early onset of hypertension and thus other cardiovascular diseases and less tolerant to physical exercises. Our results add to the evidence that hypertension is common among obese young adults.     

The correlation between the frequency of sister chromatid exchanges and the kinetics of human lymphocyte proliferation: the dependence on the sex of the donor

Sister chromatid exchanges (SCE) and average generation time (AGT) were studied in lymphocytes from 35 donors (23 females and 12 males). A higher SCE frequency was found in lymphocytes from females than from males. Smoking increased SCE frequency in lymphocytes of males, but not of females. No differences in AGTs between males and females were found. Partial correlation coefficients between SCE frequency, AGT values, donor's age and smoking were determined. A statistically significant correlation (r = 0.650, P less than 0.01) between SCE frequency and AGT was found in lymphocytes obtained from females. In lymphocytes from males statistically significant partial correlation coefficients were detected between SCE frequency and AGT (r = -0.696, P less than 0.05), SCE frequency and donor's age (r = 0.770, P less than 0.01), SCE frequency and smoking intensity (r = 0.697, P less than 0.01), AGT value and donor's age (r = 0.882, P less than 0.01), and AGT value and smoking (r = 0.634, P less than 0.05). Thus, considerable differences in number of indices between males and females exist. The present observations together with other studies (D'Souza et al., 1988) suggest that considerations for population monitoring using cytogenetic techniques (ICPEMC Publication No 14) may be supplemented with the recommendation to use (whenever it possible) only males as donors in population studies.     

Oxidative DNA damage (8-hydroxydeoxyguanosine) and body iron status: a study on 2507 healthy people

To clarify the relationship of oxidative stress and body iron status, we detected urinary 8-hydroxydeoxyguanosine (8-OHdG) as a biomarker of oxidative DNA damage, and measured serum ferritin and total iron-binding capacity (TIBC), both reflecting body iron store, on 2507 healthy people aged between 22 and 89 years (males, 1253; females, 1254). The urinary 8-OHdG excretion of males showed almost no change with age, but the excretion of premenopausal females was lower than that of males, whereas postmenopausal females excreted significantly more than males. The values of serum ferritin showed no remarkable change with age in males, but increased gradually in postmenopausal females without iron loss due to bleeding, although the males' values remained higher than those of females at all ages (p<.05). On the other hand, the values of TIBC remained within the narrow limits in males, regardless of age, whereas those of females always stayed at a higher level than the males (p<.05). Conclusively, urinary 8-OHdG correlated with serum ferritin positively and with TIBC inversely, which suggested that body iron status would control the generation of 8-OHdG in vivo. After all, the increase of urinary 8-OHdG excretion in postmenopausal females may be caused by the decrease of body iron loss.     

Sex difference in cellular calcium metabolism of rat hepatocytes and in α-adrenergic activation of glycogen phosphorylase

Three topics were the subject of these investigations: (i) the difference between males and females in the basal calcium metabolism of hepatocytes; (ii) the source of the calcium which triggers the phosphorylase a stimulation induced by epinephrine through alpha-adrenergic receptors; (iii) the time relation between the rise in phosphorylase activity and the increase in calcium efflux. We found that there was no difference between males and females in total or exchangeable cell calcium. However, there were significant differences in the mitochondrial calcium pool and fluxes measured by steady-state kinetic analyses: they were smaller and the rate constants of mitochondrial calcium influx and efflux were lower in males than in females. The ⁴⁵Ca content of isolated mitochondria and microsomes was also significantly lower in males than in females. In both males and females, epinephrine stimulated phosphorylase activity and calcium efflux even in the absence of extracellular calcium, indicating that the principal source of calcium which triggers the enzyme stimulation is intracellular. During the first 10 min following stimulation by 10^?6 M epinephrine, the total cell calcium, ⁴⁵Ca and the mitochondrial calcium were significantly depressed in male hepatocytes. After 10 min, these changes were reversed and the cell or mitochondrial calcium content was greater than in controls. In females, on the other hand, changes could only be detected if the cells were transferred to calcium-free media before the stimulation. In both males and females, there was a good temporal relationship between the stimulation of calcium efflux and the rise in phosphorylase a activity when hepatocytes were exposed to increasing concentrations of epinephrine: both rose at least 75% in less than 15 s. We conclude that there are important differences in cellular calcium metabolism between males and females. The rise in cytosolic calcium induced by alpha-adrenergic activation is principally due to a mobilization of calcium from an intracellular pool, probably the mitochondria.     

The influence of age on human pancreatic growth hormone releasing hormone stimulated growth hormone secretion

63 non-obese healthy subjects aged 18 to 95 years were investigated for age-dependence of GHRH-stimulated GH-secretion. In addition, priming of GH-secretion with three oral doses of propranolol (3 x 80 mg, the last dose 2 hours prior to the second GHRH-bolus) was carried out in 15 subjects below 40 years and 13 subjects older than 70 years. We found that mean maximal incremental GH-levels were inversely correlated with chronological age (r = -0.44, P = 0.001) of the probands. Propranolol premedication caused a significant rise of both basal and peak GHRH-induced relative increases in all subjects tested, whereas GHRH-induced relative increases of GH remained unchanged. In a well selected group of non-obese healthy subjects stimulated GH-secretion is found to undergo an aging process that is supposed to be of pituitary and suprapituitary origin. Priming GH-secretion with a beta-Blocker is possible both in young and very old healthy subjects and is likely to affect the basal GH secretory tone and not GHRH-stimulated GH-secretion.     

Palate vault morphology in Down syndrome

Moire topography was used to quantitatively determine the shape of the palatal vault in 57 Spanish patients with Down syndrome (DS) (38 males and 19 females; age range 18-36 years) and in 100 normal controls (N) (76 males and 24 females; age range 20-29 years). The topographic image for each palatal vault was analyzed and approximately 40 sets of coordinates (x, y, z) were recorded. Other parameters, including length, width and maximum height, were recorded from the palate vault images. No appreciable sexual dimorphism in palate dimensions was observed in DS subjects versus the situation in N subjects. Globally, the average N dimensions were significantly greater than those in the DS patients (P < 0.005). A special palatal morphology was found to be associated with DS, with different ratios for the three dimensions (mean factor 0.88 for length, 0.81 for width and 0.73 for height), versus the healthy palatal vaults. It is concluded that palatal morphology in DS fits an elliptic paraboloid. On the other hand, no lineal correlation was observed between height, width and length in the DS and N groups. The scatter plots of bivariate data exhibited a shapeless morphology. The lineal correlation coefficients ranged from 0.008 to 0.33 for the DS and N groups.     

Age-related alterations in NOS and oxidative stress in mesenteric arteries from male and female rats.

Epidemiological evidence suggests that advancing age affects the cardiovascular system of men and women differently. The purpose of this study was to determine whether the effects of aging on nitric oxide synthase (NOS), oxidative stress, and vascular function are different in males and females. Mesenteric arteries from young (3 mo) and old (24 mo) male and female Fischer 344/Brown Norway rats were studied. Western blot analysis and NOS activity were performed on the homogenized mesenteric arterial bed separated into cytosolic and membrane-associated fractions. Plasma 8-isoprostane measurements assessed oxidative stress. Vascular reactivity was determined by using a wire myograph in the absence and presence of a NOS inhibitor, N(omega)-nitro-l-arginine, to examine endothelial function and basal and stimulated nitric oxide release. In additional arteries, reactivity was performed in the presence of polyethylene glycol-SOD to assess the impact of superoxide on vascular function. Among females, aging was associated with a decline in membrane-associated NOS activity and membrane-associated NOS III protein expression. Advancing age in males was associated with increased cytosolic NOS III protein expression. Among both males and females, advancing age resulted in increased oxidative stress. Vascular function was maintained with age in arteries from both males and females, and there was no difference in either basal or stimulated nitric oxide release with age. Despite sex-specific effects of advancing age on the NOS system and increases in markers of oxidative stress, vascular function is maintained in mesenteric arteries from aged Fischer 344/Brown Norway rats. These data suggest that age-related alterations in the resistance vasculature are complex and likely involve multiple compensating vasoactive pathways.