Thyrocalcitonin: evidence for release in a spontaneous hypocalcemic disorder.

Thyrocalcitonin content of thyroid gland extracts from normal postparturient cows was 3.9 times greater than in cows with postparturient paresis. The parafollicular cells in diseased cows were less numerous and appeared to have discharged their secretory products. An abrupt release of thyrocalcitonin near parturition may be related to the development of the hypocalcemia and hypophosphatemia in this disorder.

Biosynthesis of vasopressin in vitro and ultrastructure of a bronchogenic carcinoma. Patient with the syndrome of inappropriate secretion of antidiuretic hormone.

Tumors from patients with the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) have been found to contain large amounts of the antidiuretic hormone vasopressin. A lung tumor from a patient with hyponatremia most likely due to SIADH was removed at surgery and found to contain 23.5 mU vasopressin/g wet weight by radioimmunoassay Slices of this tumor were incubated with phenylalanine-(3)H. Arginine vasopressin-(3)H was purified from the incubate by Sephadex G-25 column chromatography in two different systems, performic acid oxidation, and gradient elution column chromatography with diethylaminoethyl Sephadex. As oxidation of vasopressin results in drastic conformational change with breaking of the ring of the cyclic polypeptide and addition of two cysteic acid residues per molecule, the radioactive material which eluted coincident with vasopressin both before and after this procedure was considered to be arginine vasopressin-(3)H. To our knowledge this is the first demonstration of in vitro biosynthesis of vasopressin by a tumor from a patient with SIADH.Ultrastructurally, the bronchogenic carcinoma was composed of small undifferentiated and granulated cells. The granulated neoplastic cells had well developed organelles (endoplasmic reticulum, free ribosomes) concerned with protein synthesis. Secretion granules present in the tumor cells were small, surrounded by a limiting membrane, and resembled those reported in polypeptide hormone-secreting cells.

Intratibial Moloney sarcoma virus-induced osteosarcoma in the rat: tumor incidence and pathologic evaluation.

Osteosarcomas were induced in approximately 80% of young New Zealand Black rats by the intratibial inoculation of Moloney murine sarcoma virus from day 1 to day 5 after birth. The neoplasms were composed of a spectrum of well-differentiated to poorly differentiated osteoblasts, osteocytes, and osteoclasts. Budding of C-type viral particles was associated with tumor induction. Compared to rats inoculated on day 1 after birth, rats inoculated at 4 days of age developed consistently more osteoproliferative bone tumors that often were associated with hypercalcemia, increased serum alkaline phosphatase, and elevated urinary hydroxyproline.

Bone and kidney adenylate cyclase-stimulating activity produced by a hypercalcemic canine adenocarcinoma line (CAC-8) maintained in nude mice.

The tumor line CAC-8, is a serially transplantable adenocarcinoma maintained in nude mice which originated from a hypercalcemic dog. Nude mice with CAC-8 developed a syndrome of humoral hypercalcemia of malignancy. CAC-8 contained a protein factor which stimulated adenylate cyclase of bone and kidney cells in vitro. The adenylate cyclase (AC) of rat osteosarcoma cell lines, ROS 17/2.8 (ROS) and UMR-106, was stimulated by the tumor extract and potentiated by forskolin (0.1 microM). The ROS cells responded to the lowest concentration of CAC-8 extract, but UMR cells responded with a greater increase in AC activity compared to controls following exposure to CAC-8 extract. Pretreatment of ROS 17/2.8 cells with dexamethasone enhanced the response to CAC-8 extract. The opossum kidney cell line (OK) was less sensitive to the AC-stimulating activity of CAC-8 extract, but AC stimulation was increased in the presence of forskolin. Bovine (1-34) parathyroid hormone (BPTH) (10 nM) stimulated AC equally in ROS, UMR, and OK cells. Isoproterenol (1.0 microM) stimulated AC activity in ROS and UMR cells but not in OK cells. The AC-stimulating activity of CAC-8 appeared to bind to the parathyroid hormone receptor of ROS, UMR, and OK cells since addition of the parathyroid hormone receptor antagonist, [8,18norleucine, 34tyrosine]BPTH (3-34) amide, inhibited CAC-8-mediated cyclic adenosine 5'-monophosphate production and alone did not stimulate AC activity. The AC-stimulating activity of CAC-8 was acid and heat stable. Trypsin digestion reduced BPTH and CAC-8 stimulation of AC to near basal levels and treatment of CAC-8 extract with dithiothreitol reduced AC stimulation in UMR cells by approximately 50%. Extracts of the hypercalcemic tumor line (CAC-8) contained bone and kidney AC-stimulating activity which was enhanced by forskolin and dexamethasone, inhibited by [8,18Nle, 34Tyr]BPTH (3-34) amide, heat stable, trypsin sensitive, inactivated by reduction, and had a relative molecular weight of 34,000 by gel exclusion chromatography. Isolation and characterization of the factor(s) produced by CAC-8 that stimulate AC activity will be useful in further understanding the pathogenesis of humoral hypercalemia of malignancy in animal and human patients.

Early cellular abnormalities induced by RET/PTC1 oncogene in thyroid-targeted transgenic mice.

The RET/PTC1 oncogene, a rearranged form of the RET proto-oncogene, has been reported to be associated with human papillary thyroid carcinomas. We have shown that targeted expression of RET/PTC1 in the thyroid gland leads to the development of thyroid carcinomas in transgenic mice with histologic and cytologic similarities to human papillary thyroid carcinoma. To further investigate how RET/PTC1 expression contributes to the pathogenesis of papillary thyroid tumor, the time of tumor onset and the early phenotypic consequences of RET/PTC1 expression in thyrocytes were determined. All high copy transgenic mice developed bilateral thyroid tumors as early as 4 days of age. At embryological days 16-18, increased proliferation rate, distorted thyroid follicle formation and reduced radioiodide concentrating activity were identified in transgenic embryos. The reduced radioiodide concentrating activity was attributed to decreased expression of the sodium-iodide symporter. Our study showed that RET/PTC1 not only increased proliferation of thyrocytes, it also altered morphogenesis and differentiation. These findings provide a model for the role of RET/PTC1 in the formation of abnormal follicles with reduced iodide uptake ability observed in human papillary thyroid carcinoma.

Increase in thyroid follicular cell tumors in nelfinavir-treated rats observed in a 2-year carcinogenicity study is consistent with a rat-specific mechanism of thyroid neoplasia.

The carcinogenic potential of nelfinavir mesylate (nelfinavir) was evaluated in a 2-year oral (gavage) study on Sprague-Dawley rats at dose levels of 0 (control), 0 (vehicle control), 100, 300 and 1000 mg/kg per day. At the end of the treatment, increased incidences of thyroid follicular cell hyperplasia and neoplasms were observed at 300 (males) and 1000 mg/kg per day (both sexes). There were no other treatment-related effects and no tumors at other sites. Results from previous studies indicated a number of effects in the liver and thyroid, as well as metabolic profiles that suggested nelfinavir might cause thyroid hyperplasia/neoplasia secondary to hormone imbalance by altering thyroid hormone disposition. To investigate this hypothesis, the effects of nelfinavir on gene expression in rat hepatocytes and liver slices (in vitro), thyroxine plasma clearance, and thyroid gland function were evaluated. Compared to controls, gene expression analyses demonstrated an increased expression of glucuronyltransferase (UDPGT) and CYP450 3A1 in nelfinavir-treated rat hepatocytes and liver slices. In rats treated with nelfinavir (1000 mg/kg per day) for 4 weeks, liver weights and centrilobular hepatocellular hypertrophy were increased and minimal to mild diffuse thyroid follicular cell hypertrophy and follicular cell hyperplasia were evident in the thyroid gland. Thyroid-stimulating hormone (TSH) levels were significantly increased (three-fold), while tri-iodothyronine (T3)/tetra-iodothyronine (T4) and reverse T3(rT3) levels were unchanged, indicating that a compensated state to maintain homeostasis of T3/T4 had been achieved. Plasma 125I-thyroxine clearance was increased and the plasma thyroxine AUC0-48 was decreased (24%) compared to control. In conclusion, these data indicate that thyroid neoplasms observed in the nelfinavir-treated rats were secondary to thyroid hormone imbalance. Increased thyroxine clearance contributes to the effects of nelfinavir on thyroid gland function and is probably a result of UDPGT induction that leads to elevated TSH levels in the rat and eventual thyroid neoplasia. These results are consistent with a well-recognized rat-specific mechanism for thyroid neoplasms.

The effect of low calcium diet, mithramycin, and dichlorodimethylene bisphosphonate on humoral hypercalcemia of malignancy in nude mice transplanted with the canine adenocarcinoma tumor line (CAC-8).

The effect of a low calcium diet, mithramycin, or dichlorodimethylene bisphosphonate were evaluated in nude mice with humoral hypercalcemia of malignancy associated with the transplanted canine adenocarcinoma (CAC-8). Low calcium (0.01%) diet significantly reduced serum calcium levels in hypercalcemic nude mice and reduced urine calcium excretion to control levels. Mithramycin (8 mg/kg) decreased serum calcium concentration and urine calcium excretion to the range of control non-tumor-bearing nude mice at day 5 after a single injection, but there was no change in the number of tartrate-resistant acid phosphatase-positive osteoclasts in lumbar vertebrae. Osteoclasts from CAC 8-bearing nude mice after mithramycin administration were decreased in size, had small ruffled borders, and increased relative size of clear zones. Dichlorodimethylene bisphosphonate (Cl2MDP) (45 mg/kg) partially reduced serum calcium concentration of hypercalcemic tumor-bearing nude mice, decreased urine calcium excretion to control levels, and markedly reduced the numbers of tartrate-resistant acid phosphatase-positive osteoclasts in lumbar vertebrae. Osteoclasts from Cl2MDP-treated nude mice were smaller and had a reduced frequency of ruffled borders than saline-treated hypercalcemic nude mice. In vitro bone resorption induced by CAC-8 extract was significantly reduced by Cl2MDP and mithramycin. The results of these investigations suggest that the hypercalcemia and hypercalciuria associated with HHM in nude mice with CAC-8 are the combined result of altered calcium homeostasis in the bone, kidney, and intestine. Chemotherapeutic agents that specifically affect only bone or feeding a low calcium diet alone may not completely ameliorate the hypercalcemia of HHM.

Effects of gallium nitrate in nude mice bearing a canine adenocarcinoma (CAC-8) model of humoral hypercalcemia of malignancy.

Hypercalcemic nude mice bearing a canine adenocarcinoma (CAC-8) model of humoral hypercalcemia of malignancy (HHM) were treated daily with gallium nitrate (60 mg/kg of elemental gallium subcutaneously (SC) on day 0, followed by 20 mg/kg/day) for 5 days. Gallium nitrate significantly decreased (p < 0.01) serum calcium in tumor-bearing animals on days 2 and 5 of treatment (mean 13.7 +/- 0.7 mg/dl on day 0 versus 11.6 +/- 0.3 on day 2 and 12.4 +/- 0.5 on day 5). Urinary calcium excretion was decreased (p < 0.05) in the gallium-treated, tumor-bearing animals (0.11 +/- 0.01 mg calcium/mg creatinine) compared with hypercalcemic tumor-bearing mice (0.30 +/- 0.06). Both nontumor control and tumor-bearing mice treated with gallium nitrate lost body weight during the treatment period (p < 0.01). Gallium nitrate had no effect on tumor growth. Histomorphometric evaluation of lumbar vertebrae stained for tartrate-resistant acid phosphatase revealed a significant decrease (p < 0.05) in the number of osteoclasts/mm trabecular bone and perimeter of trabecular bone lined by active osteoblasts (p < 0.01) in the gallium-treated tumor-bearing mice compared with tumor-bearing controls. Osteoclast length (mm) was significantly increased in both the nontumor and tumor-bearing gallium-treated animals (p < 0.05) compared with nontumor and tumor-bearing control mice. Serum tumor necrosis factor alpha (TNF-alpha) levels were increased in tumor-bearing animals, but gallium nitrate had no effect on circulating levels (not detectable in nontumor control mice versus 82 +/- 21 pg/ml in tumor-bearing mice and 107 +/- 12 pg/ml in gallium-treated tumor-bearing mice).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of infusion of human parathyroid hormone-related protein-(1-40) in nude mice: histomorphometric and biochemical investigations.

Female nude mice were infused with 5.0, 3.0, or 1.0 micrograms/day of synthetic human parathyroid hormone-related protein (PTHrP) or control diluent with subcutaneous Alzet miniosmotic pumps for 7 days. Serum calcium was increased (p less than 0.01) on days 3 (13.9 mg/dl), 5 (13.6 mg/dl), and 7 (12.9 mg/dl) in mice infused with PTHrP at 5.0 micrograms/day compared with control nude mice (8.8 mg/dl). Serum calcium was significantly increased to a lesser degree in mice infused with 1.0 micrograms/day PTHrP (day 3) or 3.0 micrograms/day (days 3 and 7). Serum phosphorus was decreased (p less than 0.01) in all three groups of mice infused with PTHrP (4.6 mg/dl, 5.0 micrograms/day; 6.7 mg/dl, 3.0 micrograms/day; and 6.4 mg/dl, 1.0 micrograms/day) compared with controls (8.5 mg/dl). Serum 1,25-dihydroxycholecalciferol was increased (2.4-fold) in mice infused with PTHrP (5.0 and 3.0 micrograms/day). The urinary calcium-creatinine ratio (0.74 compared with 0.034 in controls) was increased (p less than 0.03) in mice infused with PTHrP (5.0 micrograms/day), but the urinary phosphorus-creatinine ratio was not different from that in controls. The urinary cAMP-creatinine ratio was increased (1.6-fold) in mice infused with PTHrP (5.0 micrograms/day). Static bone histomorphometry revealed increased (p less than 0.01) trabecular bone area, osteoblast perimeter, osteoid perimeter, osteoid width, wall width, osteoclast area, number of osteoclasts, and osteoclast perimeter in trabecular bone of lumbar vertebrae from mice infused with PTHrP. Dynamic bone histomorphometry demonstrated increased (p less than 0.01) double-labeled perimeter, mineralizing perimeter, and bone formation rate. The results of this study indicated that PTHrP increased serum calcium and 1,25-dihydroxycholecalciferol, decreased serum phosphorus, increased urinary excretion of calcium, phosphorus, and cAMP, and increased both bone resorption and formation in nude mice. PTHrP mimics the action of native PTH in vivo and is likely to be an important protein in the pathogenesis of humoral hypercalcemia of malignancy.

Spatial and temporal expression of parathyroid hormone-related protein during wound healing.

Parathyroid hormone-related protein is produced by many normal tissues including the skin, where it regulates growth and differentiation of keratinocytes. To define better the role of parathyroid hormone-related protein in the skin, we investigated the spatial and temporal expression of parathyroid hormone-related protein and mRNA by immunohistochemistry and in situ hybridization during the healing of skin wounds, and the effects of topical administration of a parathyroid hormone-related protein agonist [parathyroid hormone-related protein (1-36)] and a parathyroid hormone-related protein antagonist [parathyroid hormone (7-34)] on the healing rate and morphology of the wounds. Wounds were produced on the back of guinea pigs with a 4 mm punch, and wound sites were collected at different time points during the healing process. Parathyroid hormone-related protein was expressed in normal skin by all viable keratinocyte layers, hair follicles, and adnexae. Following injury, migratory keratinocytes at wound margins and the newly restored epidermis expressed increased levels of parathyroid hormone-related protein. The remodeling phase was associated with progressive restoration of the pattern of parathyroid hormone-related protein expression in normal epidermis. Granulation tissue myofibroblasts and infiltrating macrophages also expressed parathyroid hormone-related protein. In vitro studies using THP-1 cells (a promonocytic cell line) confirmed that macrophages expressed parathyroid hormone-related protein, especially after activation. Topical application of parathyroid hormone related protein (1-36) or parathyroid hormone (7-34) did not result in significant changes in the healing rate and morphology of the wounds. These findings demonstrated that, in addition to keratinocytes, myofibroblasts and macrophages also represent sources of parathyroid hormone-related protein during the healing of skin wounds. Although the data suggest a role for parathyroid hormone-related protein in the healing of skin and in the restoration of epidermal homeostasis, parathyroid hormone-related protein does not appear to be required for proper re-epithelialization in response to injury, potentially because of redundancy in epidermal growth and wound healing, as has been shown for other paracrine and autocrine growth factors of the epidermis.

Inhibition of in vitro bone resorption by a parathyroid hormone receptor antagonist in the canine adenocarcinoma model of humoral hypercalcemia of malignancy.

In vitro bone resorption induced by tumor extract derived from a hypercalcemic canine adenocarcinoma was significantly inhibited by the PTH receptor antagonist, [Nle8,18,Tyr34]bovine (b) PTH-(3-34) amide. Dose-response curves were prepared for in vitro bone resorption induced in neonatal mouse calvaria by tumor extract, bPTH-(1-34), and prostaglandin E2. A 1:2000-fold ratio of bPTH-(1-34) to [Nle8,18,Tyr34]bPTH-(3-34) amide significantly inhibited bone resorption induced by bPTH-(1-34); however, a 1:10,000 ratio completely antagonized bone resorption. At equivalent potency (1.80-fold stimulation of in vitro bone resorption) of tumor extract compared to bPTH-(1-34), [Nle8,18,Tyr34]bPTH-(3-34) amide (5.0 microM) was capable of significantly reducing in vitro bone resorption. Bone resorption induced by tumor extract (1.35-fold stimulation) was inhibited by [Nle8,18,Tyr34]bPTH-(3-34) amide at concentrations of 5.0 and 1.0 microM. Bone resorption induced by prostaglandin E2 (300 nM) was not inhibited by [Nle8,18,Tyr34]bPTH-(3-34) amide (5.0 microM). These data indicate that [Nle8,18,Tyr34]bPTH-(3-34) amide antagonizes in vitro bone resorption induced by bPTH-(1-34) in a dose-dependent manner and significantly inhibits bone resorption induced by the canine adenocarcinoma model of humoral hypercalcemia of malignancy.

Parathyroid hormone-related protein binding to human T-cell lymphotropic virus type I-infected lymphocytes.

An HTLV-I-infected human lymphocyte line (MT-2) was evaluated for 1) the presence of receptors for PTH-related protein (PTHrP), 2) cell proliferation in response to PTHrP, and 3) adrenylate cyclase and intracellular calcium response to PTHrP. PTHrP-(1-36) was labeled with 125I, purified, and used to detect binding to MT-2 cells. Specific binding ranged between 4-9% of the total radioactivity. Specific binding increased with increasing cell number, was maximal within 30-60 min, and was highest at 37 C. Scatchard analysis revealed a one-binding site fit, with a Kd of 14.5 nM. Binding was not competed for by calcitonin, calcitonin gene-related peptide, or interleukin-1 beta. PTHrP at 1.0 and 0.1 microM inhibited proliferation in MT-2 cells. PTHrP did not alter adenylate cyclase stimulation in MT-2 cells, but did cause an increase in intracellular calcium. These findings indicate that MT-2 cells have receptors for PTHrP and are consistent with a potential autocrine role of PTHrP in HTLV-I-infected lymphoid cells.

Effects of transforming growth factor-beta on parathyroid hormone-related protein production and ribonucleic acid expression by a squamous carcinoma cell line in vitro.

The effects of human recombinant transforming growth factor (TGF)-beta 1 were determined on PTH-related protein (PTHrP) production and messenger RNA (mRNA) expression by a canine squamous carcinoma cell line (SCC 2/88) in vitro. TGF-beta increased PTHrP production in a dose- and time-dependent manner (P < 0.05) as measured by RIA, and the effects of TGF-beta treatment persisted up to 72 h after removal. TGF-beta increased PTHrP production by SCC 2/88 cells until cellular confluence, at which time there was no longer a significant increase compared to control. Actinomycin D inhibited the TGF-beta-mediated increase in PTHrP production, suggesting that TGF-beta acted in part by increasing gene transcription. SCC 2/88 cells also produced active TGF-beta as measured by a [3H]thymidine incorporation assay in mink lung epithelial cells. Exposure of SCC 2/88 cells to a neutralizing anti-TGF-beta monoclonal antibody decreased (up to 50%, P < 0.01) basal PTHrP production. TGF-beta increased PTHrP mRNA expression in a dose- and time-dependent manner as evaluated by northern blot analysis. Postconfluent SCC 2/88 cells expressed little mRNA for PTHrP, and there was only a minimal increase in PTHrP mRNA expression in postconfluent TGF-beta-treated cells. These results indicate that TGF-beta increased PTHrP production and mRNA expression in malignant keratinocytes and suggest that TGF-beta may be an important factor in the pathogenesis of humoral hypercalcemia of malignancy.

Separation of parathyroid hormone-like activity from transforming growth factor-alpha and -beta in the canine adenocarcinoma (CAC-8) model of humoral hypercalcemia of malignancy.

A canine adenocarcinoma model (CAC-8) of humoral hypercalcemia of malignancy was evaluated for transforming growth factors (TGF)-alpha and -beta, PTH-like activity [adenylate cyclase-stimulating activity (ACSA)], and in vitro bone-resorbing activity. Biological activities present in CAC-8 were separated by reverse phase or cation exchange HPLC. TGF alpha in tumor extract was separated from TGF beta and ACSA by reverse phase HPLC. TGF alpha eluted between 26-30% acetonitrile and was identified by RIA. After the initial reverse phase separation, TGF beta and ACSA in tumor extract coeluted between 36-38% acetonitrile. Sequential cation exchange followed by reverse phase HPLC separated TGF beta from ACSA. Evaluation of fractions containing ACSA using an in vitro bone-resorbing assay demonstrated copurification of ACSA and bone-resorbing activity. The PTH receptor antagonist [Nle8,18,Tyr34]bovine PTH-(3-34)-amide, but not [Nle8,18,Tyr34]bovine PTH-(7-34)-amide, completely inhibited ACSA in column eluates. Conditioned cell culture medium from CAC-8 primary cultures contained predominantly latent TGF beta that could be activated by acidification. These findings indicate that the CAC-8 model of cancer-associated hypercalcemia produces a PTH-like factor, TGF alpha, and TGF beta that were separable by reverse phase or cation exchange HPLC. This feature should be useful to investigate the role of TGFs and PTH-like proteins in the pathogenesis of humoral hypercalcemia of malignancy.

Targeted expression of the ret/PTC1 oncogene induces papillary thyroid carcinomas.

The ret/PTC oncogene, a rearranged form of the ret proto-oncogene, has been found to be restricted to human papillary thyroid carcinomas. This report shows that transgenic mice with thyroid-targeted expression of the ret/PTC1 oncogene developed thyroid carcinomas with considerable similarities to human papillary thyroid carcinomas, particularly in the nuclear cytologic features and the presence of local invasion. Our findings indicate that ret/PTC2 is not only a biomarker associated with papillary thyroid carcinomas, but is also the only proven specific genetic event leading to the development of papillary thyroid carcinoma.

Parathyroid hormone (PTH)-related protein, PTH, and 1,25-dihydroxyvitamin D in dogs with cancer-associated hypercalcemia.

Circulating N-terminal PTH-related protein (PTHrP), N-terminal PTH, and 1,25-dihydroxyvitamin D [1,25-(OH)2D] concentrations were measured in normal dogs and dogs with cancer-associated hypercalcemia (CAH), parathyroid adenomas, and miscellaneous tumors. PTHrP was undetectable (less than 1.8 pM) in normal dogs and increased in dogs with CAH due to adenocarcinomas derived from apocrine glands of the anal sac (44.9 +/- 27 pM), lymphoma (8.3 +/- 4.4 pM), and miscellaneous carcinomas (13.3 +/- 11.4 pM). The PTHrP concentration decreased in dogs with lymphoma and anal sac adenocarcinomas after successful treatment of CAH. The PTHrP concentration had a significant linear correlation with total serum calcium in dogs with anal sac adenocarcinomas and hypercalcemia, but not in dogs with lymphoma and hypercalcemia. Serum N-terminal PTH concentrations were usually in the normal range (12-34 pg/ml) for all groups of dogs except dogs with parathyroid adenomas (83 +/- 38 pg/ml). The serum PTH concentration increased after successful treatment of CAH. Serum 1,25-(OH)2D concentrations were decreased, normal, or increased in dogs with CAH, and 1,25-(OH)2D levels decreased after treatment of CAH. In summary, circulating concentrations of PTHrP are consistently increased in dogs with CAH, and PTHrP appears to play an important role in the induction of hypercalcemia.

Thyrotoxicosis and a thyrotropin-secreting pituitary tumor causing unilateral exophthalmos.

Hyperthyroidism due to a TSH-secreting pituitary tumor has been noted by a number of investigators. We describe a unique case in which a 17-yr-old female presented with clinical hyperthyroidism, a goiter, and unilateral exophthalmos. Serum T4, free T4, and T3 (RIA) were consistently elevated along with elevated TSH levels (range, 10-100 microunits/ml). Skull x-rays and computed tomography scan revealed a tumor invading the right orbit. Other pituitary function studies were normal and LATs was undetectable. Surgery performed resulted in 70% removal of the pituitary tumor and confirmed the presence of tumor infiltration into the right orbit. TRH tests done pre- and postoperatively (patient still clinically hyperthyroid with elevated T4 and TSH levels) showed TSH and PRL responsiveness. Electron microscopy of the tumor demonstrated features typical of pituitary thyrotrophs. Monolayer cultures of pituitary cells released TSH over time into the media but did not respond to TRH stimulation. Pituitary adenoma tissue content of immunoreactive TSH was 65 microunits/g wet tissue and demonstrated immunosimilarity with human standard. We conclude that the patient had a TSH-secreting pituitary tumor responsive to TRH stimulation.

Sequences of the cDNAs encoding canine parathyroid hormone-related protein and parathyroid hormone.

The cDNA clones encoding canine parathyroid-hormone-related protein (cPTHrP) and parathyroid hormone (cPTH) have been isolated and sequenced. The predicted amino-acid sequences of the mature canine homologs have a high degree of homology to human PTHrP (hPTHrP) and PTH (hPTH), especially in the biologically active regions. The cPTHrP cDNA is unique, since it has homology to exon 1A of hPTHrP which suggests that dogs utilize a promoter similar to P1 of hPTHrP which has not been demonstrated in other species.

Investigations on in vitro bone resorbing activity from athymic (nude) and euthymic mouse splenic leukocytes.

T-lymphocyte dependence of the production of in vitro bone resorbing activity was examined using athymic (nu/nu) and euthymic (nu/+) mouse splenic leukocytes. Conditioned medium (CM) from unstimulated splenic leukocytes of nu/nu mice had greater in vitro bone resorbing activity compared to CM from nu/+ mice (1.7- as compared to 1.2-fold increase of 45Ca release in mouse calvaria). CM from concanavalin A (Con A)-treated nu/nu and nu/+ leukocytes had 1.8-fold and no increase in 45Ca release, respectively. CM from both nu/nu and nu/+ phytohemagglutinin (PHA)-treated leukocytes had a 1.7-fold increase in 45Ca release. Bone resorbing activity from nu/nu CM was inhibited by interferon-tau (10 & 100 IU/mL) and indomethacin (2 x 10(-6) M). CM (untreated or Con A-treated) from nu/nu leukocytes had higher levels of prostaglandin E (PGE) as compared to CM from nu/+ leukocytes, and indomethacin decreased PGE levels in nu/nu CM. Leukocytes from nu/+ mice had increased mitogenesis when stimulated with PHA (1, 3, & 10 micrograms/mL) or Con A (1 and 10 micrograms/mL), whereas leukocytes from nu/nu mice were nonresponsive or had significant inhibition of mitogenesis with PHA and Con A.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparison of bone turnover in athymic (nude) and euthymic mice: biochemical, histomorphometric, bone ash and in vitro studies.

Bone turnover in T-cell deficient mice was investigated by comparing parameters of bone physiology in athymic (nude) and euthymic mice. Static and dynamic bone histomorphometry, serum biochemical assays, body weight and tibia length measurements, and bone ash determination were completed in 6- and 12-wk-old athymic (nude) mice (NIH: Swiss nu/nu) and euthymic mice (nu/+) (10 mice/group). In vitro bone resorbing activity stimulated by parathyroid hormone (PTH) or prostaglandin E2 (PGE2) was measured in calvaria of neonatal athymic and euthymic mice. Athymic mice had smaller vertebral tissue area (p less than 0.01), tibia length (p less than 0.001), and less body weight (p less than 0.01) than euthymic mice. The percent double labeled surface (p less than 0.05) and mineralizing perimeter (p less than 0.01) were reduced in athymic as compared to age-matched euthymic mice. Osteoclast number was reduced in the 6-wk athymic mice as compared to 6-wk euthymic mice. Osteoclastic perimeter was reduced in the 12-wk-old mice (athymic and euthymic) as compared to the 6-wk-old mice. Serum calcium was lower at both ages in athymic mice (p less than 0.01) as compared to euthymic mice. Serum alkaline phosphatase levels were reduced (p less than 0.01) in 12-wk-old athymic mice as compared to age-matched euthymic mice, and were greater in 6-wk-old mice than 12-wk-old mice. Athymic mice had greater femur density than euthymic mice (p less than 0.01), and lower (p less than 0.001) percent ash weight of dry bone compared to euthymic mice.(ABSTRACT TRUNCATED AT 250 WORDS)