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Biomedical subjects

S Zeni

Publications and source records attributed to S Zeni.

At least 19 recordsLinked to original sources

Primary antiphospholipid syndrome associated with small aorta syndrome: a case report.

It has been widely accepted that the antiphospholipid syndrome (APS) is an autoimmune hypercoagulability syndrome in which a variety of venous and arterial thrombotic events may occur. Peripheral obliterating arterial disease characterized by aortoiliac steno-occlusion occurring in young women, is reported in the literature under the name of Small Aorta Syndrome (SAS). Although it remains unclear whether SAS represents a separate entity, the small size of the distal aorta increases the risk for aortoiliac occlusive disease. A 41-year old white woman was admitted with acute digital ischemia of the left foot. She had positive lupus anticoagulant and IgG anti-cardiolipin antibodies (61 UI/mL), but antinuclear antibodies and anti-ds-DNA antibodies were negative. She previously had two deep venous thromboses of the legs and, despite the oral anticoagulant therapy, pulmonary embolism occurred. Shortly thereafter, abdominal angio-magnetic resonance imaging suggested that the infra-renal aorta was narrowed more than 50%, without thrombotic occlusion of the terminal aorta and common iliac arteries. These findings were compatible with the features of SAS. There were no atherosclerotic changes in the artery wall and no other prediposing risk factors such as smoking, oral contraceptive or hyperlipidemia. After adequate anticoagulation and intravenous prostacyclin treatment the patient's symptoms and the ischemic lesions improved markedly. To our knowledge this is the first report of the association of SAS and primary APS. The occurrence of SAS in patients with APS may dramatically increase the risk of trombothic events.

Adult↗

Changes in bone volume and bone resorption by olpadronate treatment in an experimental model of uremic bone disease.

Thirty male adult Wistar rats (300-/+10 g body weight) underwent either 5/6 nephrectomy (Nx, n=20) or sham operation (SHAM, n=10) to determine olpadronate effects in an experimental model of uremic bone disease. For a 38-day period, 10 rats received olpadronate (16microg/100g bw) once a week (Nx+OPD) and the other vehicle (Nx). SHAM received vehicle. At baseline, treatment onset (t=7 days) and end of study (t=45 days) calcium, phosphorus, creatinine, bone alkaline phosphatase (b-ALP) and deoxypyridinoline crosslinks (DPyr) were determined. At t=0 and t=45 bone mineral density (BMD) was measured by DXA. At t=45 the right tibia was removed for bone histology. There were no differences in serum calcium. Phosphorus increased in Nx and Nx+OPD compared to SHAM (p<lt 0.05). The b-ALP increased from t=0 to t=7 in Nx and Nx+OPD (p<0.05) and decreased thereafter to SHAM levels. DPyr/creat increased in Nx compared to SHAM (p<0.05) and Nx+OPD (p<0.001). Nx+OPD presented lower DPyr excretion than SHAM rats (p<0.01). At t=45, tibia BMD of Nx was 20% and 26% lower than in SHAM (p<0.005) and Nx+OPD, respectively, (p<0.001). BMD was higher Nx+OPD than in SHAM (p<0.05). OPD prevented the loss of bone volume, the increment in osteoid volume and erosion surface observed in Nx group (p<0.05). OPD also prevent the increment in the number of osteoclasts (OC) and the active OC surface and decreases the number of TRAP(+)-OC (p<0.05). In summary, OLP may be beneficial in osteopenia associated to high turnover bone disease of CRF. However, the use of bisphosphonate therapy for renal insufficiency must be further investigated in order to clarify essential aspects of treatment as the patient selection and several aspects of treatment, such as optimum dose, frequency, and safe period of administration.

Alkaline Phosphatase↗

High prevalence of vitamin D insufficiency in healthy elderly people living at home in Argentina.

OBJECTIVE: To evaluate the nutritional status of vitamin D in urban populations of healthy elderly people living at home, in different regions of Argentina. DESIGN: Cross-sectional study. SUBJECTS: In total, 386 ambulatory subjects over 65 y of age from seven cities (between latitude 26 degrees S and 55 degrees S) were asked to participate between the end of winter and the beginning of spring. Of these, 369 accepted, 30 were excluded because of medical history or abnormal biochemical determinations. Finally, 339 subjects (226 women and 113 men) (X+/-s.d.) (71.3+/- 5.2 y) were included. RESULTS: Serum 25OHD levels were lowest in the South (latitude range: 41 degrees S-55 degrees S): 14.2+/-5.6 ng/ml (P<0.0001vs North and Mid regions); highest in the North (26 degrees S-27 degrees S): 20.7+/-7.4 ng/ml (P<0.03 vs Mid, P<0.0001vs South); and intermediate in the Mid region (33 degrees S-34 degrees S) 17.9+/-8.2 ng/ml. Serum mid-molecule PTH (mmPTH) and 25OHD were inversely related: (r=-0.24, P<0.001). A cutoff level of 25OHD at which serum mmPTH levels began to increase was established at 27 ng/ml. A high prevalence (87-52%) of subjects with 25OHD levels in the deficiency-insufficiency range (25OHD levels <20 ng/ml) was detected. CONCLUSION: This study shows that vitamin D deficiency/insufficiency in the elderly is a worldwide problem. Correction of this deficit would have a positive impact on bone health of elderly people.

Aged↗

Comparison of the effects of 3,5,3'-triiodothyroacetic Acid and triiodothyronine on goiter prevention and involution and on hepatic and skeletal parameters in rats.

3,5,3'-triiodothyroacetic acid (TRIAC) has been used to suppress pituitary TSH secretion with reported attenuation of extrapituitary effects. We investigated whether equivalent doses of T (3) and TRIAC preventing the induction of goiter by methimazole (MMI) had a different or similar impact on peripheral tissues, such as liver and bone. In particular, we compared the effects of both compounds on the activity of the hepatic thyroid hormone-responsive enzymes, malic enzyme and L-glicerol-3-P dehydrogenase; bone mineral density and biochemical parameters of bone turnover, such as bone alkaline phosphatase (b-ALP) and the carboxy-terminal telopeptide region of type I collagen (beta-CTX); and the activity of thyroid ornithine decarboxylase (ODC). We also compared the effects of T (3) and TRIAC on the involution of MMI-induced goiter. Our results showed that TRIAC was more effective than T (3) to reduce MMI-induced goiter in a short-term goiter involution assay. TRIAC increased hepatic enzymes activity and beta-CTX levels, a parameter of bone resorption, more than T (3). However, bone mineral density was not altered by either treatment. Both compounds even reduced ODC activity at doses that were not effective at the pituitary level. These results demonstrate increased TRIAC hepatic and antigoitrogenic activity compared to T (3). TRIAC induces an imbalance in bone remodeling without affecting bone mineral density. Further studies are required to clarify this point.

Animals↗

Bone mass changes in vivo during the entire reproductive cycle in rats feeding different dietary calcium and calcium/phosphorus ratio content.

The purpose of this study was to quantify in vivo the impact of different dietary Ca contents on the maternal total skeleton and skeletal sub-areas in adult rats during pregnancy and lactation, using DXA. Twenty-four female Wistar rats (approximately 5 months old) were mated and divided into three groups (n = 8) and fed one of the following diets, varying only in Ca content (LCD: 0.14%, NCD: 0.6% or HCD: 1.2%). Pups were adjusted to 8-9 per dam. Maternal ionic calcium and in vivo bone mineral density (BMD) were measured at the beginning, after delivery and after weaning. Regardless of the diet, ionized calcium decreased from onset to weaning ( P < 0.05). At weaning, bone mass decreased 7.3% in NCD, 15% in LCD and 10.5% in HCD from initial values. Total skeleton, whole and proximal tibia and spine BMDs only decreased at delivery in the LCD group ( P < 0.05) but, irrespective of the diet, at weaning, they were lower compared to delivery and initial values ( P < 0.05). LCD group presented the lowest BMD in the proximal tibia and spine regions ( P < 0.05). At birth, pups did not present differences, however, at weaning, LCD pups reached the lowest body weight ( P < 0.05), NCD presented the highest body Ca content ( P < 0.05) and there were no differences between LCD and HCD. This in vivo study showed that regardless of the dietary calcium content, the maternal skeleton is slightly affected by pregnancy but severely affected by lactation. However, the degree of such response appears to depend not only on dietary Ca content but also on dietary Ca/P molar ratio.

Absorptiometry, Photon↗

Do different aminobisphosphonates have similar preventive effect on experimental thyroid hormone-induced osteopenia in rats?

We compared similar doses of three different aminobisphosphonates (BP): olpadronate (OPD), pamidronate (APD), and alendronate (ALE) on osteopenia induced by thyroxine (T4)-treatment in OVX and SHAM adult rats. Female Sprague Dawley rats (259 +/- 8 g) were treated with vehicle (SHAM+Vh and OVX+Vh), 250 microg T4/kg/day (SHAM+T4 and OVX+T4), 0.3 mg OPD/kg/day (SHAM+OPD and OVX+OPD), 0.2 mg ALE/kg/day (SHAM+ALE and OVX+ALE), 1.5 mg APD/kg/day (SHAM+APD and OVX+APD), T4+OPD (SHAM+T4+OPD and OVX+T4+OPD), T4+ALE (SHAM+T4+ALE and OVX+T4+ALE), and T4 +APD (SHAM+T4+APD and OVX+T4+APD) during a 5-week period. At the onset and at the end of the experiment, total skeleton bone mineral density (BMD) was assessed in vivo by DXA. Lumbar spine and proximal tibia BMDs were evaluated. T4 treatment to SHAM rats did not modify BGP levels significantly: neither did ovariectomy. T4 treatment to OVX rats significantly increased bone-gla-protein (BGP) levels compared with the other studied groups (P < 0.05). BP treatment reduced BGP levels to values significantly lower than SHAM rats (P < 0.05) and reduced bone alkaline phosphatase in SHAM groups (P < 0.05) but no changes were found in OVX groups. The increased D-Pyr excretion observed in SHAM+T4 rats (P = 0.056), OVX+Vh (P < 0.05), and OVX+T4 group (P < 0.001) compared with the SHAM+Vh rats was prevented by the BP treatment. OVX+Vh rats had total skeleton and proximal tibia BMD, and OVX+T4 group had total skeleton, spine, and proximal tibia BMD significantly lower than the SHAM+Vh group. BP treatment was also found to prevent this reduction. The reduced bone resorption and the prevention of bone loss showed no differences among very close, potentially equivalent doses of the three aminoBPs used. Consequently, treatment with very close similar doses of APD, ODP, and ALE prevented bone resorption and bone changes with the same efficacy.

Alendronate↗

Reversal of CSF positivity for JC virus genome by cidofovir in a patient with systemic lupus erythematosus and progressive multifocal leukoencephalopathy.

We report the case of a 36-year-old woman affected by systemic lupus erythematosus who developed rapidly progressive multifocal leukoencephalopathy. Cidofovir therapy induced disappearance of JC virus genome from the cerebrospinal fluid and stabilization of the MRI picture. Despite the fatal outcome after a few months of disease, cidofovir treatment deserves further testing as single antiviral therapy in HIV-negative PML patients.

Adult↗

Differences in bone turnover and skeletal response to thyroid hormone treatment between estrogen-depleted and repleted rats.

This study was undertaken to compare the effect of supraphysiological doses of thyroxine (T4) on bone metabolism in SHAM and OVX young adult rats. Female Sprague Dawley rats (220 +/- 2 g, approx. 5 months of age) were divided into four groups of eight animals each. The animals were intraperitoneally injected 6 days per week with vehicle (Vh): 0.001 N NaOH/0.9% NaCl (SHAM+Vh and OVX+Vh) or 250 microg of thyroxine/kg/day (SHAM+T4 and OVX+T4) during a 5-week period. Serum T4 and osteocalcin (BGP), urinary pyridinolines (Pyr), and creatinine (creat) were determined. At the beginning and at end of the experiment, skeletal bone mineral content (BMC), bone mineral density (BMD), and area (A) of the total skeleton, femur, spine, and whole tibia, as well as proximal, middle, and distal areas of the tibia were assessed by dual X-ray absorptiometry (DXA) in an ultra-high-resolution mode. T4 treatment of the SHAM rats did not induce significant changes in BGP level or Pyr/creat excretion compared with the SHAM+Vh control group. However, these two biochemical bone markers significantly increased due to T4 treatment in OVX rats compared with both OVX+Vh and SHAM+T4 groups (P < 0.05 and P < 0.001, respectively). The OVX+T4 group had a significantly lower DeltaBMD than SHAM+T4 rats in all studied regions (P < 0.05) except for the middle tibia region. OVX+T4 groups presented a significantly lower DeltaBMC and DeltaA compared with SHAM+T4 animals (P < 0.001). OVX+T4 rats significantly impaired the DeltaBMD in the femur (P < 0.01), spine (P < 0.05), whole (P < 0.05) and middle (P < 0.05) tibia whereas T4 treatment of SHAM rats only affected, significantly, the whole (P < 0.05) and the proximal tibia region (P < 0.01). T4 treatment affects bone growth in young adult rats. The effect is significantly greater in the estrogen-depleted than in the estrogen-repleted state. The bone site most adversely affected by T4 treatment depends on the estrogen status. The proximal tibia (principally trabecular bone) was the most affected area in estrogen-repleted rats. Conversely, in OVX rats, the middle tibia (principally cortical bone) presented the greatest decrease in bone density.

Absorptiometry, Photon↗

Homocysteine concentration in primary and systemic sclerosis associated Raynaud's phenomenon.

OBJECTIVE: To investigate whether patients with systemic sclerosis (SSc) have raised homocysteine (Hcy) plasma levels, thought to be an independent risk factor for vascular disease, and to study the relationship between Hcy and endothelial damage, and between Hcy and methylene-tetrahydrofolate reductase (MTHFR) genotypes, and patients' vitamin nutritional status, which are among the more frequent causes of hyperhomocysteinemia. METHODS: We measured Hcy, von Willebrand factor (vWF), folic acid, and vitamin B12 plasma levels and analyzed the frequencies of MTHFR mutations in 30 patients with SSc and 12 patients with primary Raynaud's phenomenon (RP); 29 healthy subjects served as controls. RESULTS: Patients with SSc had higher Hcy and vWF concentrations than those with RP (p < 0.01 and p < 0.02, respectively) or controls (p < 0.02 and p < 0.0001, respectively). Folic acid and vitamin B12 were lower in SSc than in RP (p < 0.01 and p < 0.02, respectively) or controls (p < 0.05). MTHFR genotype did not influence Hcy, folate, or vitamin B12 concentrations, but patients homozygous for the mutant gene had higher vWF levels. CONCLUSION: Patients with SSc, but not those with RP, had significantly higher Hcy and vWF plasma levels. Nutritional rather than inherited factors seem to have a pathogenic role in SSc hyperhomocysteinemia.

Adult↗

Effect of one year residence in Antarctica on bone mineral metabolism and body composition.

OBJECTIVE: To evaluate the changes of the biochemical parameters of mineral metabolism and to assess the effect of these changes on the bone mass of young healthy men who voluntarily lived in the Antarctic Continent for one year. DESIGN: Lumbar spine and whole body bone mineral density (BMD) were measured pre- and post-campaign (14 months later). Serum and urinary biochemical parameters were measured every two months. Serum levels of calcium, phosphate, total alkaline phosphatase, parathormone (PTH) and 25-hydroxyvitamin D (250HD) were determined in blood fasting samples; and hydroxyproline, calcium and creatinine in 2 h fasting urine. The subjects received a dose of 100 i.u./d of vitamin D during May after obtaining the samples and then an average of 125 i.u./d from July to January. SUBJECTS: Seventeen healthy volunteers, who left Buenos Aires during the 1992 summer: ten arrived in the Belgrano II Base at the end of January and the other seven arrived in San Martín in March and stayed there up to summer 1993. RESULTS: BMD increased in lumbar spine (L2-L4), total body and the subarea of the legs but there were no differences between the pre- and post-campaign values in arms and pelvis. The percentage of fat mass decreased significantly after 1 y of residence in Antarctica, in comparison to the basal values. Most biochemical parameters remained unaltered and within the normal range during the whole study. PTH showed a nadir in March (end of the summer) when compared to initial levels (73.0 +/- 28.2 vs 39.9 +/- 32.7 pg/ml, P < 0.05), and recovered its initial value in spring. Calcium levels showed a significant decrease in March (9.5 +/- 0.4 vs 8.5 +/- 1.0 mg%, P < 0.01). 25OHD levels began to decrease in March (24.7 +/- 6.4 vs 18.7 +/- 5.3 ng/ml), reaching a minimum value whose difference approached statistical significance during the winter period (July: 16.4 +/- 8.2 ml, 0.05 < P < 0.06). No significant changes in serum phosphate, total alkaline phosphatase, urinary hydroxyproline/creatinine and calcium/creatinine ratios were found through the year. CONCLUSIONS: 25OHD levels decreased in autumn and winter (nadir in July) and recovered the initial levels by the end of the campaign. An unexplained marked diminution in PTH and serum calcium was found at the beginning of the campaign. In spite of the low vitamin D levels, bone mass in this group of young healthy men increased, probably because of their intense physical activity.

Adult↗

Determinants of bone mass in systemic lupus erythematosus: a cross sectional study on premenopausal women.

OBJECTIVE: To evaluate bone mineral density (BMD) in young ambulatory female patients with systemic lupus erythematosus (SLE) and to assess the influence of disease related variables and use of corticosteroids. METHODS: Lumbar and femoral BMD were measured by dual x-ray absorptiometry (DXA) in 84 premenopausal patients with SLE (age 30.5+/-7.5 years). All patients were receiving corticosteroids at the time of the study. Variables evaluated were: disease duration, clinical pattern, disease activity (SLEDAI), cumulative damage index (SLICC/ACR), current and cumulative prednisone dose, duration of steroid treatment, and use of immunosuppressive agents. Osteoporosis was defined as a t score below 2.5 SD compared to a reference population of healthy women in at least one region of measurement. RESULTS: Vertebral and femoral BMD were significantly lower in patients with SLE than in age matched controls. Osteoporosis was detected in 22.6% of patients. No significant differences in BMD were detected between patients according to clinical pattern or activity index, whereas patients with damage index > 0 (n = 46) had a significantly lower BMD at both the lumbar (p = 0.008) and the femoral (p = 0.05) level. Compared with non-osteoporotic patients with SLE, women with osteoporosis had similar age, lower body mass index, significantly longer disease duration (p < 0.0001), higher cumulative steroid intake (p < 0.006), and higher SLICC/ACR score (p < 0.01). Stepwise logistic regression analysis showed that disease duration is independently associated with osteoporosis (OR 1.2 for each year of disease, 95% CI 1.07-1.33). Since disease duration and duration of steroid treatment were highly correlated, a new stepwise logistic model was run without disease duration, which revealed that prednisone was associated with an increased risk for osteoporosis (OR 1.16 for each year of treatment, 95% CI 1.05-1.29). CONCLUSION: Osteoporosis is a frequent feature in young patients with SLE. Disease duration is associated with an increased risk for osteoporosis, but the role of glucocorticoid treatment seems to be crucial. Steroid exposure was the only treatment related variable exerting an influence on the development of osteoporosis.

Absorptiometry, Photon↗

Pharmacokinetic effects of conversion to a new formulation of cyclosporin A in rheumatoid arthritis patients.

In this study we aimed at evaluating the modifications in the pharmacokinetic profile of cyclosporin A (CyA) after conversion from standard formulation (CyA-ST) to a new formulation (CyA-NF, Sandimmun Neoral) in patients with rheumatoid arthritis (RA). It was an open, crossover study that involved 15 RA patients who were on stabilized treatment with CyA-ST. The patient continued receiving CyA-ST (mean dose of 3.0 +/- 0.7 mg/kg per day) for 3 weeks and then converted 1:1 to CyA-NF for a further 3 weeks. CyA pharmacokinetics were established on day 1 (CyA-ST evaluation) and +21 (CyA-NF evaluation). The results showed that the bioavailability of CyA-NF was greater than that of CyA-ST (AUC tau, bss: 3335 +/- 1300 vs 2667 +/- 1155 ng.h/ml, P = 0.0073; AUC tau, bss ratio 1.26 +/- 0.40 vs 1.0 as reference, P < 0.05), with higher and earlier peak blood concentrations (Cmax: 677 +/- 256 vs 475 +/- 213 ng/ml, P = 0.0329; tmax: 1.5 +/- 0.7 vs 2.6 +/- 1.6 h, P = 0.0720). The pharmacokinetic profile of CyA-NF showed greater between-patient reproducibility (lower CV% for all of the considered parameters). In conclusion, when using CyA-NF instead of CyA-ST, greater and more constant exposure to CyA should be expected.

Adolescent↗

The effect of olpadronate in ovariectomized thyroxine-treated rats.

Hyperthyroidism increases bone turnover and induces bone loss. This study examines the effect of thyroid hormone excess on two biochemical markers of bone turnover (hydroxyproline and bone alkaline phosphatase) as well as on bone mineral content (BMC) and bone mineral density (BMD). The possible protective role of dimethyl-APD (olpadronate, OLP), on both suppression of bone turnover and bone mineral loss in ovariectomized (ovx) rats, was also studied. Female Sprague-Dawley rats, were assigned to five groups of eight rats each: sham, ovx, ovx OLP treated (0.3 mg/kg per week), ovx T4 treated (250 micrograms/kg per day), and ovx T4-OLP rats. Rats were killed after 5 weeks of treatment. At the end of the study, blood samples were analyzed for serum calcium, phosphorus, T4, total and bone alkaline phosphatase (ALP and b-ALP), and urinary samples for hydroxyproline/creatinine ratio (HOProl/creat). Moreover, total BMC, BMD, and scanned area were determined by DXA. Ovx T4-OLP-treated rats presented higher values of b-ALP than ovx T4-treated, ovx, and sham rats (p < 0.05). Ovx increased HOProl/creat excretion compared with sham (p < 0.05), but it was similar compared with ovx T4-treated rats. OLP treatment reduced HOProl/creat excretion in both ovx T4-treated (p < 0.05) and ovx rats (p < 0.05). The final BMC in ovx was lower than in the sham group, but the difference was not statistically significant (p < 0.08). The lowest BMC was observed in ovx T4 rats (p < 0.05). When final BMC was expressed per body weight (BMC/W), ovx rats presented a significantly lower BMC/W than sham rats (p < 0.05). Ovx OLP rats had BMC/W levels higher than ovx (p < 0.005), ovx T4 (p < 0.01), and ovx T4-OLP rats (p < 0.01). The ovx group had a final BMD lower than sham animals (p < 0.05), but not significantly different than the ovx T4 rats. BMC and BMD of OLP ovx rats, whether they received T4 or not, was similar to the sham group. The highest final BMD was observed in the ovx T4-OLP group. In summary, the prevention of an increase in HOProl excretion accompanied by the fact that final BMD and BMC in OLP-treated animals were comparable to sham control rats may reflect that OLP administration could inhibit bone resorption in both T4-treated or -untreated rats. Although further studies are necessary, these findings may have clinical relevance in estrogen-depleted patients to whom medical management other than the reduction of T4 administration would be desirable.

Alkaline Phosphatase↗

Fibromyalgic syndrome: depression and abnormal illness behavior. Multicenter investigation.

This study reports psychological symptoms assessed in 327 patients with fibromyalgia (FS) in a multicenter investigation. Two self-report scales, in their validated Italian translations, were used for screening: the CES-D (the Center of Epidemiologic Studies-Depression) developed at the NIMH for measuring depression and the Illness Behavior Questionnaire (IBQ) developed by Pilowsky and Spence. The cutoff point of 23 in the CES-D scores revealed about 49% of the fibromyalgic patients as depressed. In analyzing patterns of illness behavior patients with FS showed a high score on IBQ scales of disease conviction, psychological versus somatic focusing and denial. CES-D scores showed significant correlations with illness behavior scales. These results and their implications for the treatment of fibromyalgic patients are discussed.

Adult↗

[Free erythrocyte protoporphyrin as a function of age in growing rats].

The assessment of the iron (Fe) status is very important because its deficiency is one of the most common in both developing and industrialized countries, being particularly prevalent among infants and young children. Diagnosis is difficult in the presence of other conditions which interfere with the interpretation of laboratory tests, such as hemoglobin (Hb), hematocrit (Hct), serum iron, transferrin saturation percentage and serum ferritin. Free erythrocyte protoporphyrin (FEP) is a precursor of Heme and normally occurs in very low concentration in red blood cells (RBC); elevated values indicate early impaired iron nutritional status, providing information about gradual changes in the iron supply to the marrow. This laboratory test is a practical and convenient method because it needs a small blood sample easily preserved. Although the Second National Health and Nutritional Examination Survey (NHANES II) of USA has provided a good opportunity to define more precisely the cut-off points, it is doubtful whether the age-related differences in children represent normal development or the effects of iron deficiency. In order to provide information about these aspects the present experimental model was performed: weanling Wistar rats were fed until 95 days of age (t 95) with an isocaloric diet containing 20 or 30 g/100 g. of protein (casein) (N 20 and N 30, respectively), allowing the highest growth and erythropoiesis rates and covering the requirements of all the nutrients (Table 1). Body weight and food intake were recorded three times/week.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗

Compensatory parathyroid hypertrophy after hemiparathyroidectomy in rats feeding a low calcium diet.

The functional and anatomic compensatory response of the parathyroid gland was examined in hemiparathyroidectomized (HPTx) rats whose parathyroid hormone (PTH) secretion was stimulated by a low calcium diet. These responses were compared with those observed in the thyroid gland of hemithyroidectomized (HTx) rats. Rats kept on a low calcium diet for 10 days were subjected to HPTx, HTx, or sham operations. Throughout the experiment (up to 28 days after surgery), serum calcium levels of HPTx rats were lower than the basal, with delta values (mg/dl, mean +/- SEM) of -0.66 +/- 0.17 and -0.84 +/- 0.17, (P less than 0.05) 3 and 28 days after surgery, respectively. Serum PTH decreased significantly from 7 to 21 days after HPTx, reaching normality at day 28 after surgery. In HTx rats, serum thyroxine (T4) levels diminished significantly 7 days after surgery, and attained normality thereafter. The mitotic index (number of metaphases/1,000 cells) in parathyroid glands of colchicine-treated HPTx rats increased significantly in comparison to sham-operated controls, when examined 2 or 40 days after surgery. The mitotic index of thyroid follicular cells was significantly higher than that of their respective controls, 2 but not 40 days after HTx. These results indicate that after HPTx, a delayed compensatory response is found when the animals are kept under a low calcium diet. Parathyroid response is both delayed and of a minor degree compared to that found in the thyroid gland after HTx.

Adaptation, Physiological↗