Biomedical subjects

A Bar

Publications and source records attributed to A Bar.

At least 19 recordsLinked to original sources

PubMed2004

Hormonal changes associated with ageing and induced moulting of domestic hens.

1. The effect of age on ovarian function was studied in 245-, 350-, 500-, 700- and 800-d-old Lohmann hens. The effect of three different methods for moult induction on ovarian function and corticosterone concentration was studied in 500-d-old hens. 2. No significant reductions in ovarian weight or in number of follicles before the age of 700 d were found. The ability to produce progesterone and oestradiol-17beta was unchanged up to the age of 700 d and the circadian secretion of these two steroids was identical in young (225 d) and old hens (600 d). 3. The effects of induced moulting by feed withdrawal (FW) and a high Zn (HZn) diet on body weight and ovarian function were very similar; those of a moderate Zn with low Ca (MZn/LCa) diet were smaller. 4. The first significant effect of moulting was a decrease in oestradiol-17beta plasma concentration (d 2). Plasma progesterone decreased more gradually than oestradiol-17beta, and reached a nadir on d 6 in FW- and HZn-treated hens and on d 9 in MZn/LCa-treated ones. 5. Hens treated with either FW or the MZn/LCa, but not those with the HZn diet, showed a very sharp rise in corticosterone concentration on d 2 of treatment. Thus the MZn/LCa diet was less efficient than the other treatments in induction of ovarian involution, but had a similar effect on stress induction, as indicated by increases in plasma corticosterone.

Aging↗

PubMed2003

Performance and bone development in broiler chickens given 25-hydroxycholecalciferol.

1. A series of 5 trials was conducted with Cobb chickens in order to determine the effect of 25-hydroxycholecalciferol (25OHD3) on their performance and bone development under adequate Calcium (Ca) and Phosphorus (P) supplementation, and under moderate dietary restriction of Ca and P. Formulated beadlets of 25OHD3, trade name HY-D (IsoGen, Naperville, IL, USA) were used as the 25OHD3 source. 2. Five to 10 microg of cholecalciferol (vitamin D3) or 25OHD3/kg diet were sufficient to ensure normal body weight (BW) and bone ash in chickens under continuous lighting. The two materials had similar effects on BW and bone ash. 3. In one out of the three experiments, 25OHD3 increased BW and BW gain, while in the others it had a similar effect to that of vitamin D3, or even a slight negative effect in a trial conducted on the floor, in which the diets were supplemented with the D sources at 75 microg/kg. The effects of both D sources on bone ash and on the severity or frequency of tibial dischondroplasia were similar. 4. 25OHD3 restrained the effect of moderate dietary P restriction, but not of Ca restriction, on BW gain and bone ash in 22-d-old chickens. This effect could not be explained by an higher P bioavailability in the 25OHD3-fed chickens.

Animal Feed↗

PubMed2003

Alternative procedures for molt induction: practical aspects.

Shortening daylight (to 10.5 to 11 h/d) slightly reduced the rest period (the interval between last egg and first clutch), whereas feeding a low-protein diet during the 22-d period following 8 d of feed withdrawal (FW) (recovery period) markedly extended it. Feed withdrawal accompanied by a short-daylight regime and a long recovery period led to the best postmolt production. However, production per hen housed during the whole experimental period was only slightly increased. Thus, a long rest period may mask the positive effects of short daylight and recovery diet. At least 140 to 170 d were needed to enable the molted hens to compensate for the loss of eggs during the rest period. Therefore, under certain economic conditions, rearing of nonmolting hens for 640 to 700 d should be an economic consideration. Ten days of feeding of a diet containing 0.06% nicarbazin (NICR) arrested egg production and caused a 22-d rest period but not a typical molt. Few variables of production or shell quality were improved by NICR but to a lesser extent than by FW or Zn feeding. Five days of feeding on a high-Zn diet (20 g Zn/kg; HZn) improved postmolt performances similarly to FW. Ten days of feeding on a modest-Zn (2.8 g Zn/kg), low-Ca, and low-P diet (Zn-CaP) affected postmolt performances inconsistently. In one out of two trials (trial 2), the effects of Zn-CaP were similar to those of FW or HZn; in the other (trial 3), the effects were less pronounced, more time was required for egg arrest, and more eggs were laid occasionally during the rest period. In trial 2, only the Zn-CaP diet was accompanied by short daylight. In both trials, feed intake during the induction period was only slightly reduced. Zn feeding increased the yolk Zn content slightly in eggs laid during the induction period and at the onset of production. In trial 2, only Zn-CaP markedly increased yolk Zn of eggs laid during the first 5 d of production.

Animal Feed↗

PubMed2002

Re-evaluation of calcium and phosphorus requirements in aged laying hens.

1. A series of 5 trials was conducted with 401- to 650-d-old Lohmann, Yafa (local breed with brown eggshells) and Yarkon (local breed with white eggshells) hens fed for 56 to 84 d with diets containing 25 to 50 g/kg calcium (Ca) and 4.5 to 7.6 g/kg phosphorus (P). 2. Increasing dietary Ca from 24-25 to 36-40 g/kg improved egg production, shell weight (SW) and shell thickness (ST), and decreased mortality. 3. Increasing dietary Ca to 48 to 50 g/kg did not affect egg production but increased SW and/or ST. In one out of the 4 trials, this effect was not significant, most likely because of the high shell quality of the eggs from the Yafa hens used for this trial. 4. Dietary P content of 4.5 g/kg (1.0 g/kg added inorganic P) appears to be sufficient for maintaining egg production and shell quality in aged laying hen given 36 to 40 g/kg Ca. 5. Increasing dietary Ca above 40 g/kg may require a higher dietary P content.

Aging↗

PubMed2001

Effect of age at molting on postmolting performance.

Molt was induced at the 431, 501, or 571 d, in Lohmann (L) and Hy-Line W-77 (H) hens, by 8 or 14 d, respectively, of feed withdrawal followed by a rest period of 16 d. Induced molt resulted in increases in egg production, numbers of intact eggs, egg mass per housed or surviving hen, and shell quality and in decreases in egg breakage (not significant), mortality, and culling. Egg weight was only slightly affected by molt, and the EW of hens induced to molt at 431 or 501 d of age were slightly lower than those of the unmolted hens or of those induced to molt at 571 d. Both strains reacted similarly to molt, although the L hens responded better, and expressed their responses more intensively when induced to molt earlier (431 d). This finding suggests that although different breeds have some effects of molt in common, molt protocols should be finely tuned for each breed. Total intact egg production and egg mass of the molted hens became higher than those of the unmolted hens at 650 to 728 d, which suggests that no benefit would be achieved by rearing molted hens for less than 700 to 730 d.

Aging↗

PubMed2000

Lack of response of laying hens to relative humidity at high ambient temperature.

1. The effects of relative humidity (rh=40% to 70%) at high ambient temperature (Ta) on the performance of laying hens at different ages (8 to 10 months, Trial 1; and 16 to 18 months, Trial 2) was evaluated. Laying hens were exposed to 25 degrees C (control) for 3 weeks and thereafter acclimated for 1 week to 35 degrees C and 4 different rh. 2. Body weight declined significantly in young and older hens exposed to 60% or 70% and 70% rh, respectively: Food intake declined with increasing Ta, except in the case of older hens exposed to 60% rh, for which it remained relatively constant. Water consumption, however, increased with increasing Ta but the increase was significant in young hens exposed to 70% rh only. 3. Egg production was not affected by the changes in Ta. However, a decrease in egg production was observed in older hens exposed to 60% rh. 4. Egg weight (EW), shell weight (SW) and shell thickness (ST) were significantly reduced by exposure to elevated Ta, whereas % breakage significantly increased. In young hens, a response to rh was exhibited in ST which was significantly higher in hens exposed to the low rh (40% to 45%) than in those exposed to the highest rh (70% to 75%). 5. It can be concluded that Ta is the main environmental factor affecting young and older laying hens while the effect of rh is minor.

Age Factors↗

PubMed1999

The effect of adenotonsillectomy on serum insulin-like growth factor-I and growth in children with obstructive sleep apnea syndrome.

OBJECTIVE: Obstructive sleep apnea syndrome (OSAS) in children is frequently associated with growth interruption. The objective of this study was to evaluate the effect of OSAS and adenotonsillectomy on the insulin-like growth factor-I (IGF-I) axis in children. STUDY DESIGN: Thirteen prepubertal children (mean age, 6.0 +/- 2.8 years) were studied before and after adenotonsillectomy (T&A). Weight, height, overnight polysomnography, and IGF-I and IGF-binding protein-3 levels were evaluated before and 3 to 12 months after T&A. The children's weights and heights were monitored for 18 months. RESULTS: The respiratory disturbance index improved from 7.8 +/- 9.1 events/h to 1.0 +/- 2.1 events/h after T&A (P <.02). Slow-wave sleep increased from 29.1% +/- 7.2% to 34.6% +/- 9.8% after T&A (P <.02). The weight standard deviation score increased from 0.86 +/- 1 to 1. 24 +/- 0.9, 18 months after T&A (P <.01). Serum IGF-I levels increased from 146.3 +/- 76.2 ng/mL before T&A to 210.3 +/- 112.5 ng/mL after surgery (P <.01), but IGF-binding protein-3 levels did not change significantly. CONCLUSION: The respiratory improvement after T&A in children with OSAS is associated with a significant increase in serum IGF-I levels and weight. We conclude that the IGF-I axis is affected in children with OSAS.

Adenoidectomy↗

PubMed1999

Relationships among age, eggshell thickness and vitamin D metabolism and its expression in the laying hen.

Hens forming uncalcified shells synthesized less 1,25-hydroxycholecalciferol (1,25(OH)2D3) and less duodenal and eggshell gland (ESG) calbindin than normal laying hens. Hens forming thin shells had lower intestinal and ESG calbindin and its mRNA. Reducing ESG calcium (Ca2+) transport by the carbonic anhydrase inhibitor acetazolamide, but not by dietary Ca2+ restriction, reduced ESG calbindin and its mRNA. Two sub-populations of hens characterized by shell thickness (ST) maintained this characteristic throughout the whole production period. The differences between the two sub-populations increased with age. In old laying hens, the two sub-populations responded differently to dietary Ca2+ restriction and to exogenous 1,25(OH)2D3. Those forming a thin shell responded to 1,25(OH)2D3 by a significant improvement in ST. The results suggest that: (a) the mechanism responsible for Ca2+ transport to the egg shell consists of a vitamin D-dependent absorption of Ca2+ and a multi-factor-dependent transfer of Ca2+ to the shell; (b) both steps are, most likely, calbindin-mediated; however, the induction of calbindin gene expression in the ESG is predominantly calcium-dependent; and (c) the apparent defect in vitamin D metabolism or its expression in old hens is typical of, or even exclusive, to thin-shell-forming hens.

Acetazolamide↗

PubMed1998

Regulation of osteopontin gene expression during egg shell formation in the laying hen by mechanical strain.

The aim of this study is to evaluate the regulation of the osteopontin (OPN) gene expression by non-hormonal stimuli, such as calcium flux and mechanical strain during the daily egg cycle in the oviduct of the laying hen. After the egg enters the eggshell gland (ESG), the OPN gene is expressed by the epithelium cells in two waves: first by the basal cells and only then by the apical cells of the epithelium. A reduction in OPN gene expression was observed 1 h prior to laying. The calbindin gene, which marks the onset of calcification, was found to be expressed in the glandular epithelium starting 2 h after OPN gene expression. In addition, the formation of soft shells was accompanied by a reduction in calbindin, but not in OPN, gene expression. The application of a mechanical strain comparable to that induced by an egg led to induction of OPN gene expression at a normally quiescent phase in the cyclical expression of this gene. The induction of the gene was time- and strain-dependent and temporally similar to that induced by the entry of the egg into the ESG. In contrast, the calbindin gene was not affected by mechanical strain. The ESG of the laying hen provides a system to study the effect of a mechanical strain on matrix protein production in vivo, in a relevant physiological setting. The finding suggests that, in contrast to calbindin, OPN gene expression is not regulated by calcium flux but rather by the mechanical strain imposed by the resident egg.

Animals↗

PubMed1998

Effects of age at onset of production, light regime and dietary calcium on performance, eggshell traits, duodenal calbindin and cholecalciferol metabolism.

1. Rate of production and shell thickness (ST) decreased, while body weight (BW), egg weight (EW) and percentage breakage increased progressively with age. Shell weight (SW) increased until 8 to 13 months of age and then decreased. 2. Early onset of production resulted in lower BW and EW at the onset of production, and lower pooled averages of BW, EW, SW and ST, as compared with late or medial onset of production. In 4 out of 5 trials, early onset did not result in the production of more eggs during the laying period. 3. Early onset of production is associated with physiological Ca deficiency as indicated by increases in kidney-1-hydroxylase and duodenal calbindin in early layers as compared with late layers. Early layers exhibited a more severe reduction in shell quality as the result of Ca deficiency as compared with late layers. 4. Feeding pullets with a prelaying diet containing 3.9% Ca did not affect unequivocally the performance or shell quality during the whole productive period, whether the birds started to lay early or late. The dietary treatment did not cause renal damage, as indicated by morphological examination and by plasma calcium and uric acid concentration.

Age Factors↗

PubMed1997

[The activity of renal glomeruli and tubules during uncomplicated pregnancy: influence of delivery on urinary excretion of albumin, beta 2-microglobulin and Tamm-Horsfall protein].

There were examined the influence the various types of delivery (spontaneous, oxytocin induced, cesarean section) on the value of albumin's (marker of glomerular activity), beta 2-microglobulin's (beta 2-M) (marker of activity proximal renal tubule) and Tamm-Horsfall's protein (pTH) (as a marker of activity distal's renal tubule) excretion in 50 healthy pregnant women without clinical symptoms of nephropathy. There were also estimated creating concentration in plasma and value of creating excretion in urine before and after delivery in every women. There were stated a little increase of albumin and beta 2-microglobulin but proper excretion (pTH) in urine in every group of pregnant women. There were estimated increase of albumin and pTH excretion in urine after spontaneous delivery, oxytocin inducted or cesarean section, particularly in women after cesarean section. The type of delivery had not an effect on the beta 2-microglobulin's urine excretion. The results of conducted researches suggest occurrence of functional changes in both renal glomeruli and tubules in physiologic pregnancy. The type of delivery reveals differentiated in quantity's respect the influence on albumin's and pTH excretion, but it has not an effect on beta 2-microglobulin's urine excretion.

Adult↗

PubMed1997

[Does a relationship exist between urinary excretion of Tamm-Horsfall protein and electrolytes in patients with diabetes type I and II without diabetic nephropathy?].

Studies were performed in 22 patients with diabetes mellitus type I, in 19 patients with diabetes type II, and in 15 healthy subjects. In all subjects the following parameters were assessed: creatinine clearance and 24 h urinary excretion of THP, albumin, sodium, potassium, and calcium. All studies were performed twice: first after 3 days on a normal sodium diet and subsequently after 3 days of sodium restriction (30-40 mmol Na/24 h). Urinary excretion of sodium was significantly lower in patients with diabetes mellitus type II than in healthy subjects. In patients with diabetes mellitus type I urinary excretion of sodium was significantly lower than in controls only after sodium restriction. No significant correlation was found between urinary excretion of THP and electrolytes. Results obtained in this study do not confirm presence of any relationship between urinary excretion THP and electrolytes.

Adult↗

PubMed1996

The role of gonadal hormones in gene expression of calbindin (Mr 28,000) in the laying hen.

Acute and chronic changes in calbindin (Mr 28,000) mRNA and calbindin concentrations were determined to assess the roles of steroid hormones in calbindin mRNA and calbindin synthesis in the eggshell gland (ESG). The results support an earlier suggestion that calbindin gene expression in the ESG is associated with Ca2+ flux through the ESG. The evidence includes wide oscillation of the mRNA during the diurnal egg cycle, in close temporal association with egg shell calcification. Progesterone (single im injection of 1 mg/kg body weight, BW) prolonged the period of egg formation and reduced the rate of Ca2+ transport and the concentration of calbindin mRNA in the ESG. Dexamethasone (single im injection of 5 mg/kg BW) prolonged the period of egg formation, increased shell Ca2+, and reduced calbindin mRNA in the ESG and intestine. Testosterone (single im injection of 2 mg/kg BW) did not affect calbindin mRNA synthesis in the ESG. The effects of estradiol on the synthesis of calbindin mRNA in the ESG of sexually immature or laying birds were minor, while it affected plasma Ca in the same birds. The antiestrogen Tamoxifen (60 mg/kg BW, given orally) reduced plasma Ca, but did not affect the synthesis of calbindin mRNA in the ESG. The antiprogesterone RU-38486 (20 mg/kg BW, orally) increased shell Ca2+ but had no effect on plasma Ca or the synthesis of calbindin mRNA. It appears that estrogens alone cannot account for the markedly elevated synthesis of calbindin mRNA in the ESG of the laying bird. The hypothesis that the regulatory mechanism for the synthesis of calbindin mRNA in the ESG may involve a stimulator(s), associated with the onset of production, and an oscillating depressor(s) is supported and both appear to be closely linked to the reproductive cycle. The specific in vivo effect of progesterone on calbindin mRNA in the ESG, together with its already known changes during the ovulatory cycle in birds, supports the idea that it is a depressor.

Animals↗

PubMed1995

Abnormal function of renal tubules in patients with simple renal cysts.

The present study aimed to assess the function of proximal and distal tubules in patients with simple renal cysts. Thirty-one patients with simple renal cysts and 10 healthy subjects were examined. Based on the cyst fluid/plasma sodium ratio, 25 cysts were found to be of proximal origin and 6 of undetermined origin. In all patients cyst fluid and plasma concentrations of beta-2-microglobulin (beta-2-MG), sodium, potassium, calcium, phosphorus and total protein were assessed. Urinary excretions of sodium, potassium, calcium, phosphorus, beta-2-MG and Tamm-Horsfall protein (THP) were also estimated. Fractional excretion of beta-2-MG was calculated. The concentrations of beta-2-MG in fluid obtained from cysts of proximal origin were significantly higher than in fluid from cysts of undetermined origin (2.26 +/- 0 36 vs. 0.65 +/- 0.13 mg/l, p = 0.0004). Concentrations of THP (6.85 +/- 1.21 vs. 3.14 +/- 1.06 micrograms/ml, p < 0.05), and potassium (4.39 +/- 0.07 vs. 3.13 +/- 0.44 mmol/l, p < 0.05) were also higher in fluid from proximal cysts than in fluid from cysts of undetermined origin. Plasma beta-2-MG concentration was significantly higher in patients with proximal and undetermined cysts than in the control group (4.35 +/- 0.34 and 4.11 +/- 0.74 vs. 1.89 +/- 0.1 mg/l, p < 0.001). Urinary beta-2-MG excretion was also significantly higher in both groups of patients than in healthy subjects (474.8 +/- 165.9 and 346 +/- 94 vs. 100.2 +/- 19.6 micrograms/24 h, p < 0.05). Urinary THP excretion was significantly higher in patients with proximal cysts than in healthy subjects (31.0 +/- 5.1 vs. 16.3 +/- 2.5 mg/24 h, p < 0.05). From the results obtained in this study it seems that patients with simple renal cysts of proximal origin are characterized by abnormal tubular handling of beta-2-MG, and calcium and THP excretion. Thus, in patients with proximal cysts presence of a latent renal tubulopathy seems to be likely.

Adult↗

PubMed1995

Bayley-Pinneau method of height prediction in girls with central precocious puberty: correlation with adult height.

One of the sequelae of idiopathic central precocious puberty (ICPP) can be short adult stature. In this retrospective study adult height was normal in 90% of girls with untreated ICPP (mean, 161.4 +/- 7.7 cm). The height prediction made at the time of initial examination and the height age correlated with adult height. Therefore the initial height prediction can be useful in identifying those girls with ICPP at risk for short stature.

Adolescent↗

PubMed1995

Involvement of osteopontin in egg shell formation in the laying chicken.

Expression of the osteopontin (OPN) gene in the oviduct of the laying hen was studied. It was detected only in the egg shell gland (ESG), where massive calcification occurs. No OPN gene expression was detected in any other part of the oviduct, such as the magnum and isthmus. The OPN gene was expressed in a circadian fashion during the daily egg cycle only during the period of egg shell calcification. No OPN gene expression was detected in the ESG of a pre-laying hen before the onset of reproduction, or after forced removal of the egg close to its entrance into the ESG. OPN was found to be synthesized by the epithelial cells of the ESG lining the lumen. Upon synthesis, OPN is immediately secreted out of cells and accumulates in the egg shell. These findings demonstrate for the first time temporal and spatial association of OPN with egg shell calcification. OPN, which was found to be part of the organic matrix of the egg shell, may play an important role in egg shell calcification.

Animals↗

PubMed1995

Calcium metabolism and requirements of chickens are affected by growth.

The interaction between growth and calcium homeostasis was studied by comparing the responses of (a) fast-growing broiler chickens (Cobb) and slow-growing Leghorns, and (b) fast-growing chickens (Cobb) fed either high energy (12.13 kJ/g) or low energy (9.2 kJ/g) diets, to dietary calcium concentration ranging between 4 and 20 g/kg). Plasma calcium increased as dietary calcium increased, reaching an apparent plateau between 0.8 and 1.5% dietary calcium, regardless of basal growth rate. Dietary calcium levels of 1.5% and higher induced hypercalcemia and hypophosphatemia in fast- but not in slow-growing chickens. Weight gain was unaffected by dietary calcium in the slow-growing Leghorns, but followed a bell-shaped response pattern in the fast-growing Cobb chickens. Growth inhibition by feeding of low energy diets changed the response pattern from a quadratic form to that of an increase towards a plateau. The response of bone ash to dietary calcium was characterized as quadratic in fast-growing chicks, changing to a pattern of increase towards a plateau in slow-growing chicks. Intestinal calbindin was suppressed by dietary calcium and was higher in the fast-growing than in the slow-growing chicks. An increase in dietary phosphorus resulted in a shift in the response curves of weight gain and bone ash and an increase in the calcium requirements. The results indicate that the response of chicks to dietary calcium and calcium requirements is markedly modified by growth rate.

Analysis of Variance↗

PubMed1995

[The role of "hemochromatosis alleles" in the pathogenesis of polyglobulia after renal transplantation].

43 kidney recipients were followed up for 12 months after renal transplantation. In 13 patients treated with cyclosporin A for 6 months polyglobulia was found, which subsided after conversion of immunosuppressive therapy. A highly significant correlation was found between the presence of the antigen A3 and the polyglobulia in kidney recipients treated by cyclosporin A. The serum ferritin level was not elevated in kidney recipients who were carriers of the "hemochromatosis alleles". Results obtained in this study seem to justify the following conclusions: 1. Kidney recipients who are carriers of "hemochromatosis alleles" show a threefold higher risk of posttransplant polyglobulia. 2. Presence of "hemochromatosis alleles" is not an absolute predictor of polyglobulia in patients after kidney transplantation. 3. Both etiology and pathogenesis of posttransplant polyglobulia do not seem to be homogeneous. Cyclosporin A, in contrast to azathioprine, seems to have a promoting effect on the development of posttransplant polyglobulia. Therefore treatment of kidney transplant patients with cyclosporin A, who are carriers of "hemochromatosis alleles", needs careful monitoring.

Adult↗