Dominance of HTLV type I-specific antibody responsiveness in Old World monkeys.
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Animals↗
Biomedical subjects
J A Yee
Publications and source records attributed to J A Yee.
Isolation of a simian immunodeficiency virus related to human immunodeficiency virus type 2 from a west African pet sooty mangabey.
Two of 25 healthy pet sooty mangabey (SM) monkeys (Cercocebus atys) living in West Africa were seropositive by immunoblot when surveyed for antibody to simian immunodeficiency virus of macaques (SIVmac). SIVsmLIB1 was isolated from one of the pet sooty mangabeys. Nucleotide sequence data showed that this isolate is a member of the SIVsm/human immunodeficiecy virus type 2 (HIV-2)/SIVmac group of primate lentiviruses. Furthermore, sequence comparisons revealed extensive genetic diversity among SIVsm isolates similar to that observed previously in SIV isolates from naturally infected African green monkeys. These observations provide additional evidence for monkey-human cross-species transmission of SIVsm as the source of HIV-2 infection of human.
Animals↗
SIV, STLV-I and type D retrovirus antibodies in captive rhesus macaques and immunoblot reactivity to SIV p27 in human and rhesus monkey sera.
The prevalence of simian immunodeficiency virus (SIV), simian T-cell lymphotropic virus type 1 (STLV-I), and type D retrovirus (SRV-D) antibodies was determined for 1229 rhesus monkeys (Macaca mulatta) from two research colonies. Serum samples were tested by using enzyme-linked immunosorbent assay (ELISA), immunoblot (IB), and radioimmunoprecipitation assay (RIPA). Seropositive results for the three retroviruses tested were 0 for SIV, 270 (22%) for STLV-I, and 103 (8.4%) for type D retrovirus. Of the rhesus monkey sera, 61 (5.0%) were reactive to SIV gag p27 only, when tested by IB, but were negative when further tested by RIPA. Virus isolation was attempted from cultured peripheral blood mononuclear cells of 35 monkeys whose sera contained only p27 reactivity and none were positive by reverse transcriptase and core antigen assays to detect SIV. No overt clinical signs of immunodeficiency disease or unexplained deaths were evident in either monkey colony. Additionally, 63 of 165 (38%) human sera from various groups (primate center workers, normal donors, health care workers) had weak to moderate IB reactivity only to SIV p27, but 31 of 31 sera tested were negative by RIPA. These sera remained reactive to SIV p27 following absorption with an uninfected cell lysate, after blocking IB strips with various blocking solutions and were reactive to different SIV antigen preparations while remaining negative to human immunodeficiency virus type 1 (HIV-1) by IB and negative to HIV-2 by ELISA. These data underscore the need to adopt criteria for a positive SIV serologic test requiring reactivity against more than one viral gene product. These results also illustrate a potential problem in the testing of human sera for antibodies against simian retroviruses and demonstrate the need for caution in the interpretation of immunoblot results.
Animals↗
Parathyroid hormone alteration of free and tRNA-bound proline specific activities in cultured mouse osteoblast-like cells.
The effects of the synthetic amino-terminal fragment of parathyroid hormone [bPTH-(1-34)] on proline uptake and on the specific activities of intracellular free proline and tRNA-bound proline were studied in confluent primary cultures of osteoblast-like cells isolated from neonatal mouse calvaria. Pretreatment of cells for 4 hours with 24 nM bPTH-(1-34) increased subsequent proline uptake by approximately 50-60%; also increased were the specific activities of both intracellular free proline and tRNA-bound proline when [3H]proline was included in the extracellular uptake solution. Specific activities of the free and tRNA-bound proline pools remained elevated after proline uptake times of as long as 30 minutes and 120 minutes, respectively. These results indicate that experiments in which radiolabeled proline is used to evaluate PTH-induced protein synthesis in bone cells must be interpreted cautiously, since apparent changes in protein synthesis might actually reflect, at least in part, PTH-induced changes in the specific activities of precursor pools.
Animals↗
Parathyroid hormone regulation of proline uptake by cultured neonatal mouse osteoblastlike cells.
Regulation of proline uptake by the synthetic amino-terminal fragment of bovine parathyroid hormone [bPTH-(1-34)] has been studied in confluent primary cultures of osteoblastlike cells isolated from neonatal mouse calvaria. The initial velocity of proline transport was increased by 85% in cultures treated with 24 nM bPTH-(1-34) for 6 h. Cycloheximide, at a concentration that inhibited protein synthesis by 97%, did not prevent this effect. However, adding the inhibitor during the first 1-2 h of hormone treatment did significantly reduce its magnitude. Exposure of cells to the inhibitor alone caused a time-dependent decrease in the basal rate of proline uptake. In the absence of protein synthesis, the maximal velocity (Vmax) of transport was 60% greater in cultures treated with 24 nM bPTH-(1-34) than in controls. The concentration of proline at which half-maximal transport occurred (Km) was unchanged. In cultures treated with cycloheximide alone, proline transport decreased as a first-order exponential with a half-life of 250-280 min. Parathyroid hormone significantly reduced this decline, increasing the half-life of proline transport activity about fourfold. These effects were duplicated by 1 mM DBcAMP. It is concluded that bPTH-(1-34) increases proline transport in osteoblastlike cells by decreasing the degradation of amino acid transport system A proteins. The hormone may also affect the synthesis of these molecules. These effects appear to be mediated by cAMP.
Animals↗
Inhibitory effect of [Tyr34]bPTH-(7-34)-amide on bPTH-(1-34) ability to reduce uterine contraction.
Synthetic bovine parathyroid hormone containing the 1-34 NH2-terminal amino acids [bPTH-(1-34)] inhibits uterine contraction stimulated by a variety of agonists. Previously, we reported that the parathyroid hormone analogue [Nle8, Nle18, Tyr34]bPTH-(3-34)amide [NTA-(3-34)] antagonized this effect of bPTH-(1-34) while the analogue [Tyr34]bPTH-(7-34)amide [bPTH-(7-34)] used in this study stimulated uterine contraction. However, contrary to this previous report, bPTH-(7-34) in the present study failed to initiate a contractile response and instead resulted in an inhibitory response to the bPTH-(1-34) effect on uterine contraction in a dose-related manner. The inhibitory response of bPTH-(7-34) was further confirmed by demonstrating that this preparation of bPTH-(7-34) was capable of blocking bPTH-(1-34)-stimulated adenylate cyclase activity on particulate fractions of osteoblast-like cells from neonatal mouse calvarial. These results are consistent with those in the literature for the antagonistic effect of the 7-34 PTH fragment.
Acetylcholine↗
Effect of parathyroid hormone on amino acid transport by cultured neonatal mouse calvarial bone cells.
The effect of synthetic bovine parathyroid hormone [bPTH-(1-34)] on amino acid uptake by confluent primary cultures of osteoblast-like cells isolated from neonatal mouse calvaria was studied. The uptake of proline and leucine by membrane transport Systems A, ASC, and L was discriminated on the basis of their sodium dependency and sensitivity to the system-specific amino acid analogs 2-(methylamino)-isobutyric acid (MeAIB) for System A and 2-amino-(2,2,1)-heptane-2-carboxylic acid (BCH) for System L. Treatment with 24 nM bPTH-(1-34) in serum-free EBSS for 4 hr increased the initial uptake rate of proline by 50-80% but had no effect on the uptake of leucine. Temporally, the increase in proline uptake was preceded by a 2-hr lag period and plateaued after 5-6 hr. A 5-min exposure to the hormone was sufficient to cause a significant increase in proline uptake measured 4 hr later. The magnitude of the increase was dose-related from 0.24 to 240 nM bPTH-(1-34), with the half-maximal effect occurring at 2.4 nM. Only the sodium-dependent, MeAIB-inhibitable component of proline uptake was elevated. Eadie-Hofstee analysis indicated that bPTH-(1-34) increased Vmax without changing the Km. Actinomycin D and cycloheximide prevented the hormone-stimulated increase, suggesting that RNA and protein synthesis were required. Treatment with either inhibitor alone caused a 30-35% decrease in proline transport that was not observed in the presence of bPTH-(1-34), indicating an effect not dependent on macromolecular synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Peritubular cells influence Sertoli cells at the level of translation.
Conditioned medium from cultured peritubular cells (PTCM) was capable of increasing the incorporation of amino acids into acid-precipitable material in cultured Sertoli cells, while the incorporation of uridine into acid-precipitable material was unaffected. PTCM did not influence intracellular cAMP accumulation in a manner similar to follicle-stimulating hormone (FSH). PTCM was able to stimulate androgen-binding protein (ABP) secretion by Sertoli cells even in the presence of a maximal dose of FSH. PTCM increased the rate at which peptides are elongated 5-fold over control medium or medium from control fibroblasts. These studies indicate that peritubular cells influence Sertoli cells through different mechanisms than FSH and exert their influence, at least in part, at the level of translation by increasing the rate of peptide elongation.
Androgen-Binding Protein↗
Parathyroid hormone stimulation of alkaline phosphatase activity in cultured neonatal mouse calvarial bone cells: involvement of cyclic AMP and calcium.
The involvement of cAMP and calcium in the rise in alkaline phosphatase (AP) activity observed when confluent, serum-free primary cultures of neonatal mouse calvarial cells are treated with parathyroid hormone (PTH) has been studied. Synthetic bovine PTH [bPTH-(1-34)] increased cellular cAMP at concentrations (10(-9) to 10(-7) M) previously found to elevate AP activity. Other substances that increase cAMP in these cells (forskolin, prostaglandin E2, 8-bromoadenosine cAMP and 3-isobutyl-1-methylxanthine) also increased enzyme activity. By comparison, increasing the concentration of calcium in the culture medium from 1.8 to 3.8 or 5.8 mM lowered the magnitude of the maximal AP response. In addition, treatment of cultures with the divalent cation ionophore A23187 caused a significant decrease in AP activity. These results suggest that: 1) cAMP mediates the rise in the specific activity of AP in cultured neonatal mouse calvarial cells treated with bPTH-(1-34) and 2) the concentration of calcium in the environment significantly influences the responsivity of bone cells to the hormone.
1-Methyl-3-isobutylxanthine↗
Stimulation of alkaline phosphatase activity in cultured neonatal mouse calvarial bone cells by parathyroid hormone.
The effect of parathyroid hormone (PTH) on alkaline phosphatase activity was examined in confluent, serum-free primary cultures of neonatal mouse calvarial cells. It was found that synthetic bPTH-(1-34) caused an increase in the specific activity of skeletal alkaline phosphatase isoenzyme by 18 hours. Between 10 and 500 ng/ml, the magnitude of the change was directly related to peptide concentration. The change occurred in the absence of any effect on cell number, total cell protein, or DNA and was not the result of an effect on either proliferation or survival of a specific cell population. Results of histochemical studies indicate that bPTH-(1-34) caused an increase in the proportion of cells containing enzyme activity. The response was duplicated by intact bPTH-(1-84) and DBcAMP, but not by oxidized bPTH-(1-34) or insulin and did not require prostaglandin synthesis or hydroxylation of 25-hydroxyvitamin D3. These results demonstrate that bPTH has a direct effect on osteoblast maturation in vitro, that the effect is specific for PTH, and suggest that it is mediated by cAMP.
Alkaline Phosphatase↗
Direct effect of parathyroid hormone on rat uterine contraction.
Synthetic bovine parathyroid hormone containing the 1-34 NH2 terminal amino acids [bPTH-(1-34)] is capable of inhibiting stimulated uterine contraction. The purpose of the present investigation is to determine whether the inhibitory action of bPTH-(1-34) is a direct action of the hormone fragment. The effect of different synthetic preparations of bPTH-(1-34), salmon calcitonin, corticotropin-inhibiting peptide and bovine serum albumin on oxytocin-stimulated uterine contraction was determined. In addition, the effects of atropine, propranolol, phentolamine, pyrilamine, cimetidine and the prostaglandin synthetase inhibitor indomethacin on the inhibitory action of bPTH-(1-34) on uterine contraction was determined. Both synthetic preparations of bPTH-(1-34) inhibited oxytocin-initiated contractions similarly. Salmon calcitonin, corticotropin-inhibiting peptide, and bovine serum albumin did not alter oxytocin-stimulated uterine contractions. The salmon calcitonin also did not alter the ability of bPTH-(1-34) to exert its inhibitory effect on uterine contraction. Cholinergic, alpha and beta adrenergic, histaminergic (H1 and H2) and prostaglandin synthetase inhibitors did not alter the action of bPTH-(1-34). These results suggest that the action of bPTH-(1-34) is 1) not due to the presence of a contaminant in the synthetic hormone preparation and 2) that the effect could be due to a direct action effect of the hormone fragment on uterine tissue.
Adrenocorticotropic Hormone↗
Extraintestinal calcium uptake in the killifish, Fundulus heteroclitus.
Extraintestinal calcium influxes were measured in the killifish, Fundulus heteroclitus, in solutions with different calcium concentrations, from distilled water level (near 0) to seawater level (approximately 12 mM). The extraintestinal influx is modified by the concentration of calcium in the medium during the adaptive period. In freshwater-adapted fish, calcium depletion resulted in an increase in calcium uptake. Such an adaptation was not observed in calcium-depleted fish in artificial calcium-deficient seawater. Calcium depletion in either medium seems to increase the calcium permeability. No correlation was found between Ca-ATPase activity in the gill tissue and calcium uptake.
Adaptation, Physiological↗
Properties of osteoblast-like cells isolated from the cortical endosteal bone surface of adult rabbits.
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4-Nitrophenylphosphatase↗
The effects of ethane-1-hydroxy-1, 1-diphosphonate (EHDP) on the proliferation and differentiation of stimulated periodontal ligament fibroblasts.
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Alveolar Process↗
Hypotensive actions of parathyroid hormone preparations in vertebrates.
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Animals↗
Hypotensive action of parathyroid hormone preparations on rats and dogs.
Bovine parathyroid extract and two commercial preparations containing the first 34 amino acids of synthetic bovine parathyroid hormone [bPTH-(1-34)]produced dose-related hypotension in anesthetized rats. Dogs were 10 times more sensitive to the two bPTH-(1-34) preparations than were rats. Propranolol, phentolamine, atropine, and promethazine did not affect the hypotensive action of bPTH-(1-34) in rats and dogs. bPTH-(1-34) decreased perfusion pressure in rat hindlimbs perfused in situ with Ringer's solution and was a vasodilator in dog kidneys perfused in vitro with Ringer's solution. Helical strips of rabbit aorta were also relaxed by bPTH-(1-34). We conclude that the direct vasodilatory action of bPTH preparations represents an intrinsic property of parathyroid hormone and that the hypotensive effect of this hormone is produced by part or all of the first NH2-terminal 34 amino acids.
Adrenergic alpha-Antagonists↗
Effects of synthetic parathyroid hormone on vascular beds of dogs.
Blood flow rates and vascular resistance in dogs were determined in 14 tissues with 15 +/- 2 microns radioactive microspheres (141Ce, 51Cr, 85Sr). Intravenous injections of synthetic bovine parathyroid hormone containing the NH2-terminal 1--34 amino acids [bPTH-(1--34)] at the dose of 10 USP units/kg body weight produced hypotension and increases in blood flow rate and decreases in resistance in kidney cortex, kidney medulla, heart, liver, stomach and pancreas at 1/2 and 2 min after injection. 4 U bPTH-(1--34)/kg body weight produced less vasodilation. Saline injection had no effect on the tissues studied.
Animals↗
Response of periodontal ligament cells to orthodontic force: ultrastructural identification of proliferating fibroblasts.
The morphologic response of periodontal ligament (PDL) cells in an area of tension created by orthodontic force has been assessed by transmission electron microscopy. Young adult male rats were sacrificed at 24, 48, 72, 96 and 120 hours following orthodontic stimulation. The earliest detectable response was the appearance of increased numbers of mitotic cells in the PDL at 24 hours post-stimulation. The most significant ultrastructural feature of these cells was the presence of intracellular vesicles containing collagen microfibrils. These vesicles were identical to profiles present in interphase PDL fibroblasts involved in collagen phagocytosis associated with turnover of the ligament. Between 48 and 120 hours the alveolar bone surface in the region examined was characterized by the presence of newly generated osteoblasts and active bone formation. Intracellular collagen was never observed in osteoblasts. These observations suggest that at least a portio- of the population of PDL cells which proliferate in response to orthodontic force represent functional ligament fibroblasts.
Alveolar Process↗