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S H Scharla

Publications and source records attributed to S H Scharla.

13 recordsLinked to original sources
PubMed1992

Transforming growth factor-beta 1 mRNA in neonatal ovine molars visualized by in situ hybridization: potential role for the stratum intermedium.

Human dentine contains relatively large amounts of transforming growth factor-beta (TGF-beta), which might originate from odontoblasts. The expression of the TGF-beta 1 message in developing teeth was examined by in situ hybridization. The analysis was made on 5-microns serial sections of mandibular third molars of neonatal sheep cut from tissues that had been fixed in glutaraldehyde and paraffin-embedded. A 35S-labelled cRNA probe, complementary to TGF-beta 1 mRNA, was constructed from human TGF-beta 1 cDNA. Northern analysis of total RNA from sheep placenta and neonatal third molars demonstrated hybridization to a single 2.4 kb TGF-beta 1 transcript from both tissues, indicating cross-reactivity of the human probe in the sheep. In the neonatal molars, in situ hybridization was observed in cells of the inner enamel epithelium, mature ameloblasts and mature odontoblasts, but not within preodontoblasts before dentine matrix formation. TGF-beta 1 mRNA expression was also evident in the cells of the dental papilla but scarcely so in the stellate reticulum. The most striking feature was the appearance of hybridization signal in the cells of the stratum intermedium before hybridization was evident in the inner enamel epithelium. Control sections incubated with RNAase before incubation with probe did not show evidence of hybridization. These findings suggest that TGF-beta 1 may have an important regulatory role in the differentiation of ameloblasts and odontoblasts, perhaps by modulating matrix formation during amelogenesis or odontogenesis. They also suggest a potential novel regulatory role for the cells of the stratum intermedium.

Ameloblasts↗
PubMed1991

[PTH-related protein (PTHrP) in serum of patients with tumor hypercalcemia].

Parathyroid hormone-related protein (PTHrP) is a recently described hormone, that was isolated from malignant tumors. It shows many properties of parathyroid hormone (PTH) and is related to the pathogenesis of humoral hypercalcemia of malignancy. Therefore, we analyzed PTHrP in the sera of 30 patients with hypercalcemia of malignancy and compared the values with those obtained in patients with primary hyperparathyroidism, Paget's disease of bone, and normal subjects. PTHrP was quantitated with radioimmunoassay (RIA) using aminoterminal antibodies without and with chromatographical sample purification applying SEP-PAK C18 cartridges. Measurements of PTHrP without sample purification yielded high values in all patient groups. There was no differentiation between patient groups. However, quantitation of PTHrP after SEP-PAK C18 purification of the samples resulted in values above the normal range only in tumour patients. In 30 normal subjects PTHrP levels were 110 +/- 75 pg-eq/ml. Eight out of 30 patients with malignant tumours displayed PTHrP-concentrations above 335 pg-eq/ml. PTHrP levels in patients with primary hyperparathyroidism or Paget's disease of bone were within the normal range. PTHrP concentrations were not affected from renal function. We conclude, that determination of PTHrP after sample purification may contribute to the differential diagnosis of malignant disease.

Aged↗
PubMed1991

[Therapy of Paget's disease with bisphosphonate pamidronate (AHPrBP, formerly APD)].

We studied the effect of the intravenous administration of the bisphosphonate pamidronate (AHPrBP) in 7 patients with Paget's bone disease. The medication was given in a daily dose of 20 mg for 9 days in 0.9% saline infusion over 4 hours (total dose 180 mg). Thereafter the patients received no therapy. At the end of treatment a slight but significant fall of plasma calcium (p less than or equal to 0.01) was observed, but no patient displayed hypocalcemia. The urinary excretion of hydroxyproline fell below 45% of initial within 6 days of treatment. Only 3 out of 7 patients showed a decline in alkaline phosphatase activity (AP) already at the end of treatment, but after 3 to 6 months AP was below 30% of the initial value in all observed patients. After 9 months no relapse of AP was observed. Roentgenograms demonstrated dramatic improvement of bone lesions in one case. Hyperthermia occurred in 2 patients as side effect; one patient developed headache. However, treatment could be continued in all cases. The short-term intravenous administration of pamidronate is a useful means to suppress the activity of Paget's disease and no further treatment is necessary at least for several months.

Aged↗
PubMed1991

Influence of parathyroidectomy, 1,25-dihydroxyvitamin D3 and high dietary calcium intake on demineralized bone matrix powder-induced bone formation in the rat.

Demineralized bone matrix induces ectopic endochondral bone formation. We used this model to study the effect of parathyroidectomy (PTX), 1,25-dihydroxyvitamin D3 treatment, and calcium enriched diet on bone formation in the rat. Hypocalcemia and hyperphosphatemia in PTX rats were corrected by 1,25-dihydroxyvitamin D3 treatment (2 x 12.5 ng/day) or by calcium enriched diet (3% calcium). Serum 1,25-dihydroxyvitamin D3 concentration was decreased in PTX rats and in intact rats with high dietary calcium intake. Calcium content of ectopic new bones (42 days after bone matrix implantation) was reduced in PTX rats compared with intact control rats. This could be prevented by 1,25-dihydroxyvitamin D3 treatment. In contrast, calcium enriched diet led to diminished mineralization of ectopic bones both in intact and PTX rats. We conclude that the effect of parathyroidectomy on bone formation may be mediated by 1,25-dihydroxyvitamin D3. 1,25-Dihydroxyvitamin D3 directly stimulates bone formation in this model and this effect is not simply the result of increasing serum calcium concentration.

Animals↗
PubMed1991

Osteolytic activity of Walker carcinosarcoma 256 is due to parathyroid hormone-related protein (PTHrP).

The hypercalcemic Walker carcinosarcoma 256 of the rat is an animal model for humoral hypercalcemia of malignancy. Previous in vivo studies suggested the production of a parathyroid hormone-related protein (PTHrP) by the Walker tumor. Therefore, we have measured immunoreactive PTHrP in serum-free conditioned medium from cells derived from this tumor using an antibody raised against human PTHrP(1-34). Walker tumor cell conditioned medium (WCM) displaced 125I-hPTHrP(1-34) from the antibody in a dose dependent manner, whereas control medium contained no immunoreactive PTHrP. In contrast, we detected no secretion of immunoreactive rat parathyroid hormone (rat PTH) by the Walker tumor cells using a midregional radioimmunoassay for rat PTH. WCM stimulated adenylate cyclase in osteoblast like cells, the dose-response curve paralleling that of hPTHrP(1-34). This effect could be inhibited by the PTH antagonist (8Nle, 18Nle, 34Tyr)bPTH(3-34) and by the addition of anti-hPTHrP(1-34) antibody. Bone resorbing activity of WCM in organ culture (calvaria of fetal rats) was not inhibited by indomethacin and glucocorticoids, suggesting a prostaglandin independent mechanism of osteoclast activation in this model.

Adenylyl Cyclases↗
PubMed1991

1,25-Dihydroxyvitamin D3 differentially regulates the production of insulin-like growth factor I (IGF-I) and IGF-binding protein-4 in mouse osteoblasts.

1,25-Dihydroxyvitamin D3 [1,25-(OH)2D3] induces differentiation and inhibits proliferation in many cell types including bone cells. These effects may be mediated by the modulation of the insulin-like growth factor (IGF) regulatory system. Therefore we investigated the effects of 1,25-(OH)2D3 on transcript and protein levels of both IGF-I and IGF binding proteins (IGFBPs) in clonal mouse osteoblasts. Subconfluent cultures were treated in serum-free medium with 1,25-(OH)2D3. Secreted IGF-I was measured using a RIA under conditions eliminating the interference of IGFBPs. 1,25-(OH)2D3 (10(-11)-10(-8) M) inhibited IGF-I release in a dose dependent manner at 24 h (maximally to 30 +/- 5% of control, mean +/- SEM of seven independent experiments). In a time course study IGF-I increased in the media of control cultures over a 48-h period, while IGF-I secretion was completely prevented from 6 h onward in 1,25-(OH)2D3 treated cultures. Northern blot analysis revealed four IGF-I transcripts of 0.9, 1.8, 4.4, and 7.5 kilobases (kb). 1,25-(OH)2D3 decreased levels of the 7.5 kb IGF-I transcript from 4-48 h, with maximal inhibition occurring at 24 h (25% of control). Western ligand blots of the culture medium demonstrated secretion of a 25-kilodalton IGFBP, which comprised greater than or equal to 90% of the secreted IGFBPs. The 25-kilodalton IGFBP had previously been shown to have sequence similarity with IGFBP-4, a binding protein which inhibits the action of IGFs on bone cells. 1,25-(OH)2D3 treatment increased secretion of IGFBP-4 up to 14-fold over 24 h. 1,25-(OH)2D3 also increased IGFBP-4 (2.2 kb) transcript levels within 30 min, with the maximal stimulation of 8-fold occurring after 8 h. [3H]Thymidine incorporation into cells was inhibited by 1,25-(OH)2D3 both under basal and serum-stimulated conditions. Our results are consistent with the hypothesis that the effects of 1,25-(OH)2D3 on osteoblast proliferation may be mediated in part by decreased levels of IGF-I and increased concentrations of inhibitory IGFBP-4. It is proposed that this alteration in the IGF system may be an important functional autocrine or paracrine switch in the transition of osteoblasts from states of proliferation to differentiation.

Animals↗
PubMed1990

Bone mass reduction after estrogen deprivation by long-acting gonadotropin-releasing hormone agonists and its relation to pretreatment serum concentrations of 1,25-dihydroxyvitamin D3.

Estrogen deficiency results in bone mass reduction of largely varying extent in postmenopausal females, indicating that additional mechanisms influence the response of bone. They are by no ways identified in either the animal experiment or under clinical conditions. In search for factors, conditioning the response of bone to estrogen deficiency, we have conducted a study in females under treatment with the GnRH agonist decapeptyl (D-Trp6-LHRH). This drug blocks ovarian function and was administered for treatment of endometriosis or uterine leiomyoma. We determined spinal (dual photon absorptiometry) and forearm (single photon absorptiometry) bone mineral density before and 3 and 6 months after the onset of therapy and measured biochemical parameters of bone metabolism. Our results showed an increase in bone turnover after initiation of estrogen deficiency, as indicated by the elevation of alkaline phosphatase and osteocalcin. This resulted in a secondary decrease in serum intact PTH and 1,25-dihydroxy-vitamin D3. Furthermore, we found a positive correlation between pretreatment values of serum 1,25-dihydroxyvitamin D3 as well as its decrease and the reduction in bone mass during GnRH agonist treatment. This demonstrates that the patients' metabolic conditions predict their response to estrogen deficiency.

Adult↗
PubMed1989

Treatment of tumor hypercalcemia with clodronate.

In an open, controlled study 34 patients with tumor hypercalcemia of different origin were treated with clodronate. The initial dosage was 300 mg intravenously daily. After achieving normocalcemia, treatment was continued orally using 400-3200 mg/day depending on serum calcium concentration. Most patients showed normocalcemia within 1 week of treatment - only few of them needed a longer time. Fifteen of 34 patients died within the observation time of up to 24 weeks, some being normocalcemic. However, a reincrease in plasma calcium during treatment was an indicator of deterioration. Measurements of plasma parathyroid hormone (PTH) using an intact molecule radioimmunometric assay showed depressed levels before clodronate treatment started, but PTH rose after achieving normal and especially low normal calcium levels. Starting 1,25-dihydroxycholecalciferol [1,25(OH)2D3] values were decreased or in the lower normal range in the majority of patients, but in 6/21 patients plasma 1,25(OH)2D3 was in the upper normal range or elevated despite hypercalcemia. After lowering plasma calcium the 1,25(OH)2D3 levels increased. However, there was no significant correlation between PTH and 1,25(OH)2D3. Therefore we assume that in some patients additional stimulation of renal 1 alpha-hydroxylase by tumor products is present.

Administration, Oral↗
PubMed1989

The hypercalcemic Walker carcinosarcoma 256 of the rat causes an increase in serum 1,25-dihydroxyvitamin D3.

We have studied vitamin D metabolism in rats with the transplantable hypercalcemic Walker carcinosarcoma 256, which is a well characterized animal model for humoral hypercalcemia of malignancy. 25-Hydroxyvitamin D3 (25(OH)D3) and 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) concentrations were determined in blood samples obtained from parathyroidectomized (PTX) female rats at different time intervals after intramuscular tumor cell inoculation. We observed a dramatic increase in serum 1,25(OH)2D3 (280 +/- 184 vs. 98 +/- 31 pmol/l) 6 days after tumor cell injection and 4 days after the initial rise of serum calcium, whereas 25(OH)D3 tended to decrease. In a separate control experiment we compared this to the effect of exogenous parathyroid hormone in PTX rats and found similar results. In contrast, rats exhibited no change in vitamin D metabolite blood concentration after inoculation of the normocalcemic Yoshida sarcoma, which obviously does not interfere with vitamin D metabolism. We conclude that the humoral bone-resorbing agent produced by the Walker tumor cells causes elevation of serum 1,25(OH)2D3 concentration by this fulfilling an additional criterion of PTH-like activity.

Animals↗
PubMed1989

1,25-Dihydroxyvitamin D3 prevents the decrease of bone mineral appositional rate in rats with inflammation-mediated osteopenia (IMO).

We have studied the effects of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) on bone mass and bone mineral appositional rate in intact rats and rats with inflammation-mediated osteopenia (IMO), where osteoblast number and mineral appositional rate are decreased. 1,25(OH)2D3 prevents IMO-specific bone loss when given in a daily dose of 25 ng per rat, but does not when given in higher doses. The hormone was effective, when given over the complete duration of the experiment (21 days), but not when given over shorter time periods (7 and 14 days, respectively). 1,25(OH)2D3 prevents IMO-dependent reduction in mineral appositional rate and leads to an only moderate increase in intact rats. We conclude, that 1,25(OH)2D3 is more effective in stimulating mineral appositional rate in rats with IMO where mineral apposition is impaired.

Animals↗
PubMed1989

Reversible bone loss in women treated with GnRH-agonists for endometriosis and uterine leiomyoma.

Oestrogen deficiency at the menopause is associated with changes in calcium and bone metabolism. Hypo-oestrogenism induced by the use of GnRH-agonists is clinically useful in the treatment of oestrogen-dependent diseases. This study was done to investigate calcium homeostasis and bone metabolism of pre-menopausal women in a GnRH-agonist-induced pseudo-menopause. Eighteen patients with endometriosis or uterine leiomyoma received monthly i.m. injections of 3.2 mg of long-acting D-Trp-6-LHRH over a 6-month period. Plasma oestradiol-17 beta and progesterone levels under treatment were significantly decreased to the levels of the early follicular phase. Plasma total calcium, serum osteocalcin and plasma alkaline phosphatase concentrations increased, while plasma phosphate levels did not change. Levels of 1,25-dihydroxyvitamin D3 decreased significantly, but 25-hydroxyvitamin D3 values remained constant. Trabecular bone mineral density of lumbar spine decreased continuously during the 6-month period. Nine women completed 6-9 months follow-up. In these women bone loss was reversible. Cortical bone measurements at the proximal radius showed no change during oestrogen deficiency. In conclusion, our findings demonstrate that GnRH-agonist-induced bone loss is reversible. Furthermore, they suggest that the state of pseudo-menopause induced by GnRH-agonist may serve as a model for further pathophysiological studies on calcium homeostasis and bone metabolism in the post-menopause.

Adult↗
PubMed1987

[Treatment of tumor hypercalcemia with clodronate. Effect on parathormone and calcitriol].

Clodronate (dichlormethylene diphosphonate) was administered to 21 patients with hypercalcemia due to malignant tumor. The drug was initially given intravenously, then orally. In 20 patients the serum calcium level had been reduced to the normal range within one week of the start of treatment (from 3.3 +/- 0.5 mmol/l to 2.4 +/- 0.3 mmol/l). With oral administration there was a renewed rise in calcium levels in some patients, which had to be treated with higher oral doses or intravenous administration. Parallel with the reduction in calcium levels there was an improvement in the originally impaired renal function. The serum level of intact parathormone(1-84) and 1.25-dihydroxy-vitamin-D3 (calcitriol) rose significantly from usually lowered initial levels. There was a non-linear inverse correlation between parathormone and calcium. No side effects were noted, even after long-term administration.

Adult↗