Biomedical subjects

E Bucht

Publications and source records attributed to E Bucht.

At least 37 records · Page 2Linked to original sources

PubMed1996

Circulating monomer-like calcitonin in osteoporotic patients.

Physiological concentrations of monomeric calcitonin can inhibit osteoclastic bone resorption in vitro. We therefore investigated the circulating molecular forms, including monomer-like calcitonin, and their concentrations in 9 men and 9 women with established osteoporosis. Calcitonin was immunoextracted from serum by the use of rabbit calcitonin antibodies coupled to Sepharose 4B. The lyophilized extracts were incubated with 6 M urea overnight and gel chromatographed in a fast protein liquid chromatography (FPLC) system; calcitonin was measured by radioimmunoassay in the fractions. FPLC disclosed immunoreactive calcitonin of three different molecular sizes in the patients. The two largest forms were approximately 30 and 10 kDa and one eluted at the same position as monomeric calcitonin (3.4 kDa). After extraction and FPLC we found slightly higher calcitonin concentrations in osteoporotic women than previously reported levels in age-matched healthy women. Male patients had higher levels than female patients. None of the osteoporotic patients lacked monomer-like calcitonin. There was no significant correlation between the extracted total or monomer-like calcitonin and bone mineral density of the femoral neck. It is concluded that the circulating calcitonin in both male and female patients comprises three different molecular forms and that there is no deficiency of the monomer-like form. The calcitonin levels in the female patients were slightly higher than in a previous control group.

Aged↗

PubMed1996

Estimation of the C-cell numbers in rat thyroid glands using the optical fractionator.

We estimated the total number of calcitonin-immunoreactive C-cells in rat thyroid gland using the optical fractionator, the unbiased stereological method for estimation of numbers. It was necessary first to use a fixative composed of formalin, acetic acid, and ethanol to distinctly visualize the C-cells. The 40-microm-thick sections had to adhere to chromalum-gelatin-coated Superfrost Plus glass slides, and the immunostaining technique had to stain the C-cells evenly throughout the whole sections. Because the C-cells were irregularly distributed in the thyroid tissues, their counting required screening of about 500 fields per lobe, but the number of C-cells counted need not be high, about 90 per lobe. We estimated that rats have 185,000 +/- 42,000 C-cells (mean +/- SD; n - 7). The C-cell population did not differ significantly between the two lobes of a given rat, but it varied markedly among rats. The biological differences among the animals contributed 83% to the observed variability, whereas the methodological uncertainty contributed 17%. The serum levels of calcitonin and calcium were not closely correlated to the C-cell numbers. Our results indicate that variability in C-cell experiments can be reduced most effectively by increasing the number of animals used. However, the similar C-cell frequency found in the two thyroid lobes of each rat allows the use of one uniformly sampled lobe for quantification and the other lobe for further analysis.

Animals↗

PubMed1995

Serum calcitonin forms and concentrations in young and elderly healthy females.

To further investigate the role of calcitonin (CT) in normal physiology we studied circulating forms and the secretion after "calcium clamp" in young and elderly healthy females. Heterogeneity of CT in serum was disclosed after immunoextraction, fast protein liquid chromatography, and radioimmunoassay in young (27 +/- 3 years; mean +/- SD, n = 6) and elderly females (69 +/- 6 years, n = 11). Three distinct molecular forms appeared with approximate mol wt of 30, 10, and 3-4 kDa. All young women studied had considerable amounts of circulating monomer-like CT whereas several elderly had undetectable or low levels. The influence of age on basal and calcium stimulated, immunoextracted CT in serum was also studied in young (26 +/- 4 years; mean +/- SD, n = 13) and elderly (63 +/- 6 years; n = 12) healthy females. The calcium stimulation was carried out by means of the standardized calcium clamp method, where calcium was kept on a presettled level at 1.45 mmol/liter (+/- 2%) for 60 minutes. CT was immunoextracted from serum in all series of experiments with a polyclonal antiserum directed against the mid- and carboxyterminal region of the CT molecule, and the amount of extracted CT was determined by radioimmunoassay using another polyclonal antiserum against the carboxyterminal portion. After calcium infusion, the increase in CT was significantly higher in young women than in elderly (P < 0.05). At basal conditions, the CT levels were not significantly different but slightly higher in young than in elderly females. In conclusion, several elderly women lack monomer-like calcitonin in serum in contrast to young women.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Pronounced elevation in circulating calcitonin in critical care patients is related to the severity of illness and survival.

OBJECTIVE: To study circulating levels of calcitonin in critically ill patients in relation to the severity of illness and survival. DESIGN: Cross-sectional and prospective. SETTING: The ICU in Gävle hospital, a secondary non-teaching hospital. PATIENTS: 37 consecutive ICU patients. MEASUREMENTS AND RESULTS: Serum calcium and immunoreactive calcitonin (iCT) were measured and the Apache II and the Multiple Organ Failure (MOF) scores were recorded during the first 24 h in the ICU. Patients were followed for hospital survival. Profound increase in circulating iCT was seen (mean 591, median 184, range 8-3445 pg/ml) in the studied sample and only 11% of the patients showed normal levels (< 40 pg/ml). iCT was higher in septic than nonseptic patients (p < 0.004) and was correlated to two indices of severity of illness (r = 0.50, p < 0.006 versus the Apache II score and p = 0.55, p < 0.003 versus the MOF score). Furthermore, iCT was correlated to the length of stay in the intensive care unit (r = 0.56, p < 0.001) and was elevated in the patients who did not survive when compared to survivors (p < 0.03). iCT was not significantly related to the degree of serum calcium (mean 2.22 +/- 0.15 SD mmol/l). Gel chromatography in a fast protein liquid chromatography (FPLC) system of serum from 4 patients with elevated iCT disclosed that a majority of the measured CT was not due to monomeric CT, but high molecular CT. CONCLUSIONS: Pronounced elevations in circulating iCT were seen during the first 24 h critically ill patients. As the major part of the iCT consisted of high molecular weight CT this would not induce hypocalcemia. Rather, the elevated iCT would be regarded as a part of the metabolic responses to illness.

APACHE↗

PubMed1995

Midmolecular parathyroid hormone-related peptide in serum during pregnancy, lactation and in umbilical cord blood.

Indications of an important physiological role of parathyroid hormone-related peptide (PTHrP) for fetal calcium homeostasis, maternal-fetal calcium transport and reproduction have accumulated over recent years. The PTHrP concentrations were measured by an earlier developed midregion radio-immunoassay in serum from lactating healthy females and umbilical cord blood and compared with levels in age-matched non-pregnant or lactating females. The PTHrP concentrations could be measured in all samples after silica cartridge C18 extraction of 10-12 ml of serum. The concentrations were significantly higher during lactation (mean +/- SD: 0.72 +/- 0.14 pmol/l, N = 22) and in umbilical cord blood (0.85 +/- 0.18 pmol/l, N = 12) compared with healthy age-matched women (0.48 +/- 0.09 pmol/l, N = 10, p < 0.001). The molecular forms of PTHrP were also studied in an age-matched control group, in pregnant women and in umbilical cord blood by gel chromatography in a fast protein liquid chromatography system of Sep-Pak-extracted pooled serum. In all three groups we found heterogeneity of the molecular forms with two predominant peaks. The smallest fragment had a molecular weight of 4-6 kD while the largest form appeared as a high-molecular-weight molecule. In conclusion, the concentrations of midmolecule PTHrP fragments in serum are elevated during lactation and in umbilical cord blood. Because the midregion of PTHrP has unique actions, our results indicate that PTHrP may play an important physiological role for the mother and for the maternal-fetal calcium transport.

Chromatography, Liquid↗

PubMed1994

Parathyroid hormone-related protein is produced by cultured endothelial cells: a possible role in angiogenesis.

Parathyroid hormone-related protein (PTHrP) is produced by various normal and neoplastic tissues. Even if the physiological function(s) of PTHrP is unclear, evidence suggests that the protein may participate in the local regulation of smooth muscle contractility. We show here that PTHrP is produced in endothelial cells cultured from human umbilical veins as demonstrated both at the mRNA and protein level. The expression of PTHrP can be upregulated by the phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate, which is known to stimulate endothelial cell differentiation and angiogenesis in vitro. Unlike smooth muscle cells, the endothelial cells do not express the parathyroid hormone (PTH)/PTHrP receptor mRNA, nor could specific binding of the protein be detected. We therefore suggest that PTHrP produced by endothelial cells acts on smooth muscle cells and may be of importance for the growth and development of new vasculature.

Cells, Cultured↗

PubMed1994

Polyamines regulate human medullary thyroid carcinoma TT-cell proliferation and secretion of calcitonin and calcitonin gene-related peptide.

The significance of polyamines for the neoplastic proliferation and secretion of calcitonin (CT) and calcitonin-gene-related peptide (CGRP) by the human medullary thyroid carcinoma TT cell line was investigated. TT cells were cultured in vitro for 6 days with or without additions of pathway inhibitors of polyamine biosynthetic enzymes. Treatment of the cells with 1 mM of the specific L-ornithine decarboxylase (ODC) inhibitor DL-alpha-difluoromethylornithine (DFMO) resulted in a 97% decrease in ODC activity, lowered contents of putrescine (96%) and spermidine (85%) and cell proliferation rates (90%) along with a compensatory 15-fold increase in S-adenosyl-L-methionine decarboxylase (SAMDC) activity. DFMO treatment also led to a decrease in cellular content of CT (33%) and CGRP (26%), while the drug enhanced secretion of CT (31%) but depressed that of CGRP (26%), and elevated the ratio of CT to CGRP secreted into the medium by 74%. Ethylglyoxal bis(guanylhydrazone) (EGBG), a SAMDC inhibitor, at 100 microM evoked a similar reduction of cell proliferation and lowered the content of spermine by 81%. Furthermore, EGBG treatment caused a 34-fold increase in ODC activity and a subsequent 35-fold build-up of putrescine, but also seemed to stabilize SAMDC as evidenced by a highly enhanced SAMDC activity (approximately 200-fold) during enzyme assays in the absence of the inhibitor. EGBG exposure resulted in an increase in cellular CT content (110%) and secretion of the hormone (82%), while not affecting CGRP content or release.2+ EGBG effects were partially counteracted by DFMO.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosylmethionine Decarboxylase↗

PubMed1994

Blood sampling procedures influence serum calcitonin concentrations in rats.

The aim of this study was to determine whether serum calcitonin (S-CT) in rats is influenced by the method of taking blood samples. Sampling during halothane anaesthesia, after repeated administration of anaesthesia after a 14-day interval, and sampling without the use of anaesthetics (i.e. after the rats were made unconscious by stunning), resulted in different S-CT values (P < or = 0.001), whereas Ca2+ levels were not affected. In thyroidectomized rats, the S-CT values after stunning were not significantly different whereas those in sham-operated rats were different (P < or = 0.01). The possibility that anaesthesia may suppress stunning-induced changes in S-CT was explored in three other groups of rats subjected to halothane anaesthesia, stunning and stunning under halothane anaesthesia respectively. Although the S-CT level was highest after stunning and lowest in halothane-anaesthetized rats (P < or = 0.001), anaesthesia did not suppress the effect of stunning on S-CT. In conclusion the effect of sampling procedures must be considered in studies on the levels of S-CT in rats.

Anesthesia↗

PubMed1994

Calcium homeostasis in normal pregnancy and puerperium. A longitudinal study.

Calcium homeostasis was longitudinally followed in serum and urine throughout normal pregnancy and the puerperium in 23 healthy women. From the 14th week of gestation, samples were obtained every fourth week until the 38th week. Post partum samples were obtained on the fifth day and after eight weeks. In the serum the total calcium decreased continuously during pregnancy. The ionized calcium and phosphate levels remained unchanged and within the reference interval for non-pregnant women. The alkaline phosphatase level progressively increased and high levels were found at term. The magnesium and hematocrit values remained below, whereas the calcitonin level remained just above the reference interval throughout pregnancy. The parathyroid hormone was low initially and increased towards term but within the reference interval. The urine excretion of calcium was constantly high, close to the upper reference limit, and renal function was slightly improved. At the last sampling eight weeks after delivery, all values were within normal limits for non-pregnant women. Calcium homeostasis is considerably changed during pregnancy and non-pregnant reference limits are not often valid.

Adolescent↗

PubMed1994

Sensitive time-resolved fluoroimmunoassay of salmon calcitonin.

A two-site assay was developed by use of the "dissociation and enhancement lanthanide fluoroimmunoassay" (DELFIA) technique for determination of salmon calcitonin (SCT) in serum after administration to osteoporotic patients. Polyclonal antibodies were produced in rabbits immunized with SCT coupled to ovalbumin. After affinity purification, the antibodies were used both as immobilized capture antibodies and as Eu-chelate-labeled signal antibodies. A sensitive assay with a detection limit of 1.1 pmol/L was achieved, and no cross-reaction with human calcitonin was observed. The intra- and interassay CVs were < 12% (n = 10) and < 15% (n = 4), respectively. Analytical recovery of SCT added to serum was 91% +/- 3% (mean +/- SD, n = 4). SCT was measurable in all the samples from eight osteoporotic patients after subcutaneous SCT administration. We conclude that this new sensitive and specific two-site DELFIA can reliably measure SCT in serum.

Aged↗

PubMed1993

Influence of smoking and snuff use on electrolytes, adrenal and calcium regulating hormones.

Little is known about the effects of snuff use on health. We have investigated electrolyte levels, adrenocortical and calcium regulating hormones in three groups of healthy young men, including 18 non-tobacco users, 21 snuff users and 19 smokers with similar age and body mass index. Smoking and snuff use was positively associated with alcohol and coffee consumption and inversely related to physical activity. Compared to non-tobacco users, smokers had significantly increased levels of serum sodium and magnesium, plasma calcitonin, urinary cortisol and potassium levels and decreased serum sex hormone-binding globulin as well as serum and urinary creatinine values. However, only decreased sexual hormone-binding globulin and urinary creatinine and increased serum phosphate and urinary potassium levels were seen in snuff users. Among tobacco users we noted that smokers differed from snuff users in that they had higher serum sodium (1.4 mmol/l, p < 0.01), plasma calcitonin (3.3 pmol/l, p < 0.05) and urinary cortisol (41 nmol/24 h, p < 0.05) but lower serum creatinine (5.8 mumol/l, p < 0.01). We conclude that chronic snuff use appears to have less influence on hormone and electrolyte balance than does smoking, and that some of the abnormalities seen in smokers do not seem to be mediated by nicotine.

Adrenal Cortex↗

PubMed1993

Plasma calcitonin, IGF-I levels and vertebral bone mineral density in hyperprolactinemic women during bromocriptine treatment.

Hyperprolactinemia is associated with decreased bone mineral density, which may be caused by the hypogonadism and hypoestrogenicity noticed in patients with hyperprolactinemia. Since calcitonin inhibits the bone resorption, and insulin-like growth factor I (IGF-I) has important anabolic effects on the skeleton, lack of one or both peptides may contribute to the development of osteopenia. We therefore measured the plasma calcitonin and IGF-I levels in nine women with hyperprolactinemia caused by a prolactin-producing pituitary tumor. The calcium-stimulated C-cell reactivity was studied by measuring calcitonin in plasma during a calcium clamp before and after normalization of serum prolactin during treatment with bromocriptine. Basal CT levels were measurable but lower than in healthy controls. Basal IGF-I levels and calcium-stimulated plasma calcitonin were normal in the hyperprolactinemic state and similar to the calcitonin and IGF-I levels during bromocriptine treatment. The serum prolactin levels decreased (p < 0.001) and the serum estradiol levels increased (p < 0.001). The bone mineral density of the lumbar spine increased significantly during treatment. Thus, basal plasma CT levels are slightly reduced in hyperprolactinemic women. However, the reversible osteopenia in hyperprolactinemic women is less likely to be caused by inhibited IGF-I secretion or by deficient CT levels since the CT response to calcium is normal. In addition, bromocriptine treatment with normalization of prolactin levels is beneficial for the bone mineral content in this condition.

Adult↗

PubMed1992

Parathyroid hormone-related peptide in human milk measured by a mid-molecule radioimmunoassay.

Several peptide hormones and growth factors have been found in human milk, and we present here the results of measurements of parathyroid hormone-related peptide (PTHrP). A radioimmunoassay (RIA) using a polyclonal antiserum against the mid-region of the molecule has been developed. In milk collected during the first 6 days after parturition, the PTHrP concentrations showed large interindividual variations ranging from 0.3 to 13.7 nmol-Eq/L (0.5 to 24.4 ng-Eq/mL) (n = 67) and increased between days 3 and five postpartum. PTHrP also increased during the first 4 collecting days when measured in milk from the same mother during a prolonged period. On fast-protein liquid chromatography (FPLC), the bulk of PTHrP eluted with a molecular weight of approximately 10 to 12 kd after treatment with urea. After mid-molecule immunoaffinity extraction of PTHrP from milk, higher levels were obtained by the mid-molecule RIA than by an aminoterminal assay, indicating that all fragments did not contain the aminoterminal. Parts of immunoextracted milk PTHrP stimulated cyclic adenosine monophosphate (cAMP) production in rat osteosarcoma cell line, UMR-106. In conclusion, we have found PTHrP-like immunoreactivity in human milk using a mid-region RIA. Parts of the immunoextracts also contained the aminoterminal and possessed PTH-like bioactivity. Whether PTHrP in human milk plays a physiological role in the maternal breast or in the newborn gastrointestinal tract is unknown, but the present observations demonstrate that a portion of the PTHrP is at least potentially biologically active.

Biological Assay↗

PubMed1992

Calcium homeostasis in pregnancy during long-term heparin treatment.

OBJECTIVE: To investigate the effect of subcutaneous heparin treatment on calcium homeostasis in pregnancy. DESIGN: A longitudinal case-control observational study. SETTING: Department of Obstetrics and Gynaecology, Karolinska Hospital, Stockholm, Sweden. SUBJECTS: 36 pregnant women with previously verified thromboembolic complications and 23 healthy pregnant control women similar in age, parity, weight, and smoking habit. INTERVENTIONS: Thromboprophylaxis during pregnancy and 6 weeks post partum was given with subcutaneous heparin twice daily to the 36 women with a history of thromboembolic complications, 16 received an average dose of 24,500 IU/day and 20 a mean dose of 17,300 IU/day. Venous blood and urine samples were obtained every 4 weeks. MAIN OUTCOME MEASURES: Serum concentrations of total calcium, ionized calcium, calcitonin and urinary calcium. RESULTS: Women on high-dose heparin treatment showed significantly higher concentrations of total and ionized calcium and of calcitonin in serum and significantly lower concentrations of calcium in urine than did 23 normal pregnant controls. The differences were most pronounced in the third trimester. The results obtained in the low-dose heparin group were between those in the high-dose and the control groups. At 8 weeks postpartum there were no significant differences between the heparin-treated women and the controls. No significant differences were found during pregnancy in haematocrit, liver or renal function, serum levels of albumin, phosphate, magnesium, alkaline phosphatase, parathyroid hormone or urinary cyclic AMP. CONCLUSIONS: Heparin treatment during pregnancy results in changes in calcium homeostasis and a dose-dependent response is suggested.

Adult↗

PubMed1992

Parathyroid hormone-related peptide, measured by a midmolecule radioimmunoassay, in various hypercalcaemic and normocalcaemic conditions.

The diagnosis of humoral hypercalcaemia of malignancy often presents considerable clinical problems. We have studied parathyroid hormone-related peptide (PTHrP) in serum from patients with humoral hypercalcaemia of malignancy (N = 22), hypercalcaemia of malignancy with skeletal metastases (17), histologically confirmed primary hyperparathyroidism (21) and hypercalcaemic patients with various benign diseases (9). PTHrP measurements were also made in normocalcaemic patients with various malignancies (23), endocrine diseases (13), sarcoidosis (22) and chronic renal failure (17). PTHrP was measured by a novel radioimmunoassay using rabbit antibodies directed towards the midregion of the molecule. Immuno- or silica cartridge extraction of serum before radioimmunoassay enabled us to measure PTHrP in all samples, which may add further information about circulating forms of PTHrP. PTHrP was clearly elevated in patients with humoral hypercalcaemia of malignancy (5.0 +/- 4.7 pmol/l) (mean +/- SD, N = 12) and when the kidney function was impaired (4.0 +/- 0.9 pmol/l) (N = 15) (silica cartridge extraction), whether the subject was hypercalcaemic or not. Some patients with endocrine diseases, including two with primary hyperparathyroidism, had slightly elevated serum PTHrP concentrations, while they were normal in sarcoidosis. In healthy subjects the levels were 1.1 +/- 0.5 pmol/l (N = 15) after immunoextraction and 0.8 +/- 0.2 pmol/l (N = 33) after silica cartridge extraction.

Aged↗

PubMed1991

A rapid extraction method for serum calcitonin.

A rapid, simple and reliable extraction method for calcitonin from serum has been developed. 2 volumes of acidic ethanol and 1 volume of serum were mixed, centrifuged, and the supernatant was evaporated to dryness. The extracts were reconstituted in assay buffer before radioimmunoassay was performed. Basal concentrations of calcitonin after extraction were 5.4 +/- 3.0 pg-equivalents/ml (mean +/- SD), females, n = 48 and 8.8 +/- 5.5 pg-equivalents/ml, males, n = 42. Calcitonin was detectable in serum from all males and from 90% of the females. The concentrations in males were significantly higher (P less than 0.001). There was a more pronounced calcitonin response in males (n = 12) than in females (n = 12) to a calcium clamp (P less than 0.01). Gel chromatography of serum from patients with medullary thyroid carcinoma on a Sephadex G-75 column and a TSK G 2000 SW column in a fast protein liquid chromatography system, disclosed that the ethanol extraction excluded the high mol mass forms of calcitonin. We propose the acidic ethanol extraction as a convenient method for routine measurements of calcitonin.

Calcitonin↗

PubMed1991

Salmon calcitonin treatment by nasal spray in primary hyperparathyroidism.

The hypocalcemic and hypophosphatemic effect of salmon calcitonin (sCT) given by intranasal (i.n.) spray to 12 patients with histological confirmed primary hyperparathyroidism (1 degree HPT) was studied. The concentration of ionized calcium in whole blood (B-Ca++), serum phosphate (S-P), magnesium (S-Mg), plasma sCT (Pl-sCT), and endogenous CT (hCT) was followed during five 24-hour periods with at least three days between. After period I (control day), 100 IU sCT was given intramuscularly (i.m.) in period II. In periods III-V, either 110, 200, or 400 IU of sCT were given intranasally (i.n.) in randomized order. Although B-Ca++ decreased from the baseline value with all four sCT treatments and at 4.5 hour on the control day (p less than 0.05-0.001), the i.n. sCT treatments had no significant hypocalcemic effect, as the change of the area under the B-Ca++ curve (delta AUC B-Ca++) for the three i.n. treatments was not significantly different from the control period (p less than 0.001, ANOVA). Only the i.m. injection of calcitonin had a calcium-lowering effect (p less than 0.001, ANOVA). Three subjects were considered nonresponders with a decrease in B-Ca++ less than 0.06 mmol/L. S-P decreased within three hours after 200 IU sCT i.n. and 100 IU i.m., but the S-Mg levels showed no consistent changes. The area under the curve for the Pl-sCT levels did not correlate with delta AUC B-Ca++ except for i.m. given sCT.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Intranasal↗

PubMed1990

Plasma calcitonin levels in patients with cystic fibrosis.

Plasma levels of calcitonin were investigated in patients with cystic fibrosis and compared with age- and sex-matched healthy controls. About forty per cent of the cystic fibrosis patients had plasma calcitonin levels that were markedly higher than normal. Elevated levels were found predominantly in female patients. In general, patients with marked pulmonary involvement had high plasma calcitonin levels. Immunoextraction and gel chromatography, carried out on plasma of one of the patients demonstrated monomer-like forms of calcitonin similar to those found in the healthy subjects.

Adolescent↗