In vivo regulation of hemopoiesis by transforming growth factor beta 1: stimulation of GM-CSF- and M-CSF-dependent murine bone marrow precursors.

Injection of mice with either natural bovine bone-derived or human recombinant transforming growth factor beta 1 (TGF-beta 1) resulted in a significant increase of the macrophage and macrophage-granulocyte-forming capacity of their macrophage colony-stimulating factor (M-CSF)- and granulocyte-macrophage colony-stimulating factor (GM-CSF)-dependent bone marrow precursor cells. The increased potential for generating granulocytes and/or macrophages from bone marrow cells of mice injected with TGF-beta 1 was associated with an increase of the number of M-CSF- and GM-CSF-dependent bone marrow colony-forming units (CFU). The effect was selective, in that in vivo applied TGF-beta 1 did not affect interleukin 3 (IL-3)-dependent CFU. The data suggest that TGF-beta may be useful in recovery of bone marrow granulocyte- and macrophage-forming potentials following depletion caused by chemo- or radiotherapy.

Calcium receptor messenger ribonucleic acid levels in the parathyroid glands and kidney of vitamin D-deficient rats are not regulated by plasma calcium or 1,25-dihydroxyvitamin D3.

The level of extracellular ionized calcium ([Ca2+]o) is the primary physiological regulator of PTH secretion. Complementary DNAs encoding the calcium receptor (CaR) protein that mediates this response have been cloned from bovine and human parathyroid glands. This protein is a seven-transmembrane, G-protein-coupled receptor linked to the mobilization of intracellular Ca2+ in response to increases in [Ca2+]o. More recently, a rat kidney CaR has been cloned and shown to be 92% identical at the amino acid level to the bovine parathyroid CaR. Homologous or heterologous regulation of the expression and/or function of a variety of G-protein-coupled receptors has been documented in numerous cell types. Therefore, we determined whether [Ca2+]o and 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3], major regulators of PTH synthesis and secretion, affect CaR gene expression in parathyroid gland and kidney in rats. CaR messenger RNA (mRNA) levels were quantified in pairs of parathyroid glands and single kidneys from individual animals using a solution hybridization assay. The effects of Ca2+ and 1,25-(OH)2D3 on CaR gene expression were assessed independently in vitamin D-deficient (-D) rats. A wide range of plasma Ca2+ levels (0.7-1.9 mM) was produced by supplementing -D diets with varying amounts of calcium and by infusing CaCl2 i.v. for 7 days using osmotic minipumps. There was no correlation between plasma Ca2+ levels and steady state CaR mRNA levels in parathyroid gland (r = -0.18) or kidney (r = 0.25). In another group of -D rats, 1,25-(OH)2D3 was infused sc at 25 and 275 ng/kg.day for 10-12 days. Dietary calcium was adjusted to maintain normocalcemia in some of the groups. No effect of 1,25-(OH)2D3 administration on CaR mRNA levels occurred in parathyroid glands or kidney regardless of the resultant plasma Ca2+ or 1,25-(OH)2D3 levels. In conclusion, neither parathyroid gland nor kidney CaR mRNA levels are regulated by plasma Ca2+ and 1,25-(OH)2D3 levels in the experimental models examined here.

Parathyroid gland calcium receptor mRNA levels are unaffected by chronic renal insufficiency or low dietary calcium in rats.

Extracellular ionized calcium (Ca(2+)) is the primary physiological regulator of parathyroid hormone (PTH) secretion and the G protein-coupled receptor (CaR) that mediates this response has been cloned from bovine and human parathyroid glands. The Ca(2+) set-point for the regulation of PTH secretion is right-shifted in primary hyperparathyroidism (1°HPT), but whether there is a similar shift in 2°HPT is unclear. Additionally, the molecular defects associated with such changes in the set-point remain uncharacterized. These experiments were designed to determine (1) if changes in set-point occur in rats with 2°HPT induced by chronic renal insufficiency (CRI) or dietary Ca deficiency, and (2) whether any changes in set-point are mirrored by changes in steady-state mRNA levels for the parathyroid CaR. CaR mRNA levels were quantified in pairs of glands from individual rats using a solution hybridization assay. Blood urea nitrogen and PTH levels were ∼ 4-fold higher in rats with CRI induced by 5/6 nephrectomy 7 weeks earlier. Rats with CRI were also significantly hypocalcemic and hyperphosphatemic. The setpoint was unchanged in CRI rats and CaR mRNA levels were also unaffected. Normal rats fed a 0.02% Ca diet for 6 weeks were markedly hypocalcemic, and had 10- and 15-fold increases in plasma PTH and 1,25-dihydroxyvitamin D(3) levels, respectively. Technical problems prevented assessment of the set-point in these animals, but parathyroid gland CaR mRNA levels were identical in both dietary groups. Thus, neither alterations in mRNA levels for the CaR nor changes in the set-point play demonstrable roles in the pathogenesis of 2°HPT in these models.

Immunomodulation in an apparently non-immunogenic murine tumor.

Madison lung carcinoma (M109), a murine tumor of spontaneous origin, appears to be non-immunogenic, according to 2 commonly employed tests for tumor immunogenicity. However, C.parvum-induced immunopotentiation during the growth of M109 tumor results in post-excision anti-tumor immunity to M109 tumor implants. The C.parvum-potentiated post-excision immunity to M109 is tumor-specific and T-cell-dependent. T cells from mice whose progressive M109 tumors have been excised are capable, on passive transfer, of inhibiting adoptive immunotherapy of T-cell-deficient recipients by spleen cells from mice immunized with an admixture of M109 cells and C.parvum. The data are interpreted as evidence supporting the hypothesis that the apparent lack of anti-tumor immunity in this tumor model is not due to the absence of tumor-associated antigens. We suggest that, instead, in this model the balance between the effector and suppressor arms of the immune response favors tumor-induced immunosuppression, resulting in a magnitude of anti-tumor immunity insufficient for detection by commonly employed tests for tumor immunogenicity. Our study shows that shifting the balance in favor of the effector arm by means of immunopotentiation results in a measurable immune response to an apparently non-immunogenic tumor.

NPS R-568: a type II calcimimetic compound that acts on parathyroid cell calcium receptor of rats to reduce plasma levels of parathyroid hormone and calcium.

Calcimimetics like N-(3-[2-chlorophenyl]propyl)-(R)-alpha-methyl-3-methoxybenzylamine (NPS R-568) potentiate the effects of extracellular Ca(2+) on parathyroid Ca(2+) receptors and inhibit parathyroid hormone (PTH) secretion in vitro. When administered by gavage to normal rats in this study, NPS R-568 caused a rapid, dose-dependent (ED(50), 1.1 +/- 0.7 mg/kg) decrease in PTH levels that was paralleled by a subsequent decrease in plasma Ca(2+) (ED(50), 10.4 +/- 3.7 mg/kg). At higher doses (>/=3.3 mg/kg), PTH was reduced to a minimum level within 15 min, the duration of which was dose dependent. With doses of 10 to 100 mg/kg, the hypocalcemia was rapid in onset (<30 min) and, at 33 to 100 mg/kg, persisted for >24 h. Neither the magnitude nor the kinetics of the hypocalcemic response was affected by total nephrectomy, demonstrating that NPS R-568 does not induce hypocalcemia by acting on renal Ca(2+) receptors to increase Ca(2+) excretion. In contrast, parathyroidectomy (intact thyroid) abolished the hypocalcemic response to NPS R-568, regardless of whether the rats were hypocalcemic or rendered acutely normo- or hypercalcemic by calcium infusion before dosing. These data show that the parathyroid Ca(2+) receptor can be selectively activated in vivo with a small organic compound to decrease plasma levels of PTH and Ca(2+) and thus define the mechanism of action of this compound in vivo. Moreover, the data add pharmacological support to the view that the Ca(2+) receptor is the primary molecular entity regulating systemic Ca(2+) homeostasis.

Calcimimetic compound NPS R-568 stimulates calcitonin secretion but selectively targets parathyroid gland Ca(2+) receptor in rats.

N-(3-[2-Chlorophenyl]propyl)-(R)-alpha-methyl-3-methoxybenzylamine (NPS R-568) is an orally active compound that activates Ca(2+) receptors on parathyroid cells and rapidly suppresses plasma levels of parathyroid hormone (PTH) and Ca(2+) (ED(50), 1 and 10 mg/kg, respectively). We now show that increased calcitonin secretion contributes to NPS R-568-induced hypocalcemia. In parathyroidectomized thyroid-intact rats in which normocalcemia was restored by PTH infusion, NPS R-568 rapidly reduced plasma Ca(2+) levels, indicating that decreased PTH secretion was not solely responsible for the hypocalcemia seen in normal animals. NPS R-568 decreased plasma Ca(2+) levels in thyroidectomized parathyroid-intact rats, but the rate of onset of hypocalcemia was slower than in controls. In contrast, NPS R-568 had no effect on plasma Ca(2+) levels in PTH-infused, thyroparathyroidectomized rats, providing evidence that increased calcitonin secretion caused the hypocalcemia in PTH-infused parathyroidectomized rats. NPS R-568 rapidly increased plasma calcitonin levels to a peak at 10 to 20 min after oral dosing (ED(50) 40 mg/kg). NPS R-568 did not affect the rate of disappearance of (45)Ca from blood, indicating that hypocalcemia resulted from decreased influx of Ca(2+) into the circulation and not from increased efflux. This suggests that NPS R-568-induced hypocalcemia resulted solely from reduced efflux of Ca(2+) from bone after increased calcitonin and reduced PTH secretion. Thus, NPS R-568 causes hypocalcemia by activating Ca(2+) receptors on C cells and parathyroid cells; however, NPS R-568 is about 40 times more potent in reducing PTH levels than in increasing calcitonin levels.

Optimal method of urgent decompression of the collecting system for obstruction and infection due to ureteral calculi.

PURPOSE: We compare the efficacy of percutaneous nephrostomy with retrograde ureteral catheterization for renal drainage in cases of obstruction and infection associated with ureteral calculi. MATERIALS AND METHODS: We randomized 42 consecutive patients presenting with obstructing ureteral calculi and clinical signs of infection (temperature greater than 38 C and/or white blood count greater than 17,000/mm.3) to drainage with percutaneous nephrostomy or retrograde ureteral catheterization. Preoperative patient and stone characteristics, procedural parameters, clinical outcomes and costs were assessed for each group. RESULTS: Urine cultures obtained at drainage were positive in 62.9% of percutaneous nephrostomy and 19.1% of retrograde ureteral catheterization patients. There was no significant difference in the time to treatment between the 2 groups. Procedural and fluoroscopy times were significantly shorter in the retrograde ureteral catheterization (32.7 and 5.1 minutes, respectively) compared with the percutaneous nephrostomy (49.2 and 7.7 minutes, respectively) group. One treatment failure occurred in the percutaneous nephrostomy group, which was successfully salvaged with retrograde ureteral catheterization. Time to normal temperature was 2.3 days in the percutaneous nephrostomy and 2.6 in the retrograde ureteral catheterization group, and time to normal white blood count was 2 days in the percutaneous nephrostomy and 1.7 days in the retrograde ureteral catheterization group (p not significant). Length of stay was 4.5 days in the percutaneous nephrostomy group compared with 3.2 days in the retrograde ureteral catheterization group (p not significant). Cost analysis revealed that retrograde ureteral catheterization was twice as costly as percutaneous nephrostomy. CONCLUSIONS: Retrograde ureteral catheterization and percutaneous nephrostomy effectively relieve obstruction and infection due to ureteral calculi. Neither modality demonstrated superiority in promoting a more rapid recovery after drainage. Percutaneous nephrostomy is less costly than retrograde ureteral catheterization. The decision of which mode of drainage to use may be based on logistical factors, surgeon preference and stone characteristics.