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L J Deftos

Publications and source records attributed to L J Deftos.

At least 55 records · Page 3Linked to original sources
PubMed1997

Densitometric patterns of spinal cord injury associated bone loss.

The purpose of the study was to use dual energy X-ray absorptiometry to measure bone mineral density (BMD) in the lumbar spine, the femoral neck, Ward's triangle, and the greater trochanter in 204 men (69 able-bodies controls and 135 spinal cord injured patients) stratified according to age (20-39, 40-59, and 60+ years old) in order to determine whether changes in BMD were age related, and to determine when these changes began to appear. The BMDs of the lumbar spine of both the 40-59 year old and the 60+ year old patients were significantly higher (P < or = 0.012) than the 40-59 year old and 60+ year old controls, respectively. The femoral region BMDs of the 20-39 year old and the 40-59 year old patients were all significantly lower (P < or = 0.027) than the 20-39 year old and 40-59 year old controls, respectively. When patients were grouped according to the time since their injury (0-1, 1-5, 6-9, 10-19, 20-29, 30-39, 40-49, and 50-59 years post injury) within the various age categories different results were obtained. In all the age categories, BMD loss occurred starting one year after spinal cord injury in the hip region. This bone loss took place gradually, reaching a significant plateau (P < or = 0.017) at 19 years post injury and then started improving. The spine BMD in our patient population never significantly decreased, and started improving as the age of the injury increased. Findings presented for the femoral regions were similar to other investigators' findings; however, the steady bone mass maintained in the lumbar area, which increased with age regardless of the age of the injury, with the bone mass loss in the hip area, were the most notable new findings.

Absorptiometry, Photon↗
PubMed1997

Demineralization in tetraplegic and paraplegic man over time.

The aim of the present study was to compare bone mineral density (BMD in g/cm2) in the lumbar spine and three hip regions of male spinal cord injured subjects at various times post injury to age-matched able-bodied controls and to correlate their BMDs to their age and level of their spinal cord lesion. Patients and controls were stratified into three 20 years age groups (20-39, 40-59, and 60+ years of age). BMD measurements were obtained using dual energy X-ray absorptiometry (DEXA, Lunar Model DPX). BMD levels taken within the first year of injury were not significantly lower than the age-matched able-bodies controls. The 20-39 year old patients injured longer than 1 year had significantly lower (P < or = 0.01) BMDs in their femoral region than both their age matched controls and the 20-39 year old acutely injured (injured for less than 1 year) patients. Although femoral BMDs of both paraplegic and quadriplegic patients 40-59 and 60+ years of age decreased over time, none showed significant bone loss in this regions until 10 years after their injury. These results indicate that spinal cord injury associated bone loss occurs most dramatically in the femoral region of young men. These results also indicate that initial bone mass loss does not occur prior to 1 year post-injury to the extent that it is detectable by densitometry, or at least it did not occur in our patients.

Absorptiometry, Photon↗
PubMed1997

Parathyroid hormone-related protein, an autocrine growth inhibitor of alveolar type II cells.

Parathyroid hormone-related protein (PTHRP) is an autocrine regulator of differentiation for type II pneumocytes [R. H. Hastings, D. Summers-Torres, T. C. Cheung, L. S. Ditmer, D. W. Burton, E. M. Petrin, R. G. Spragg, J. Li, and L. J. Deftos. Am. J. Physiol. 270 (Lung Cell. Mol. Physiol. 14): L353-L361, 1996]. We investigated autocrine effects on growth by decreasing endogenous PTHRP in rat type II cells. Cultured cells were incubated with antibodies against PTHRP-(1-34) (8B12) or PTHRP-(109-141) (9H7) or an irrelevant antibody (1 microg/ml) for 3 days. Conditioned media from the irrelevant antibody group contained 143 +/- 8 fg PTHRP/ 100,000 cells. The 8B12 and 9H7 reduced levels to 45 +/- 8 and 88 +/- 16 fg PTHRP/100,000 cells, respectively (n = 4 cell isolations, P < 0.05). Cells treated with the PTHRP antibodies nearly tripled in number. The irrelevant antibody had no effect on growth. Exogenous PTHRP-(1-34) (2.5 nM) blocked the growth-stimulating effect of 9H7. Instilled intratracheal 8B12 and 9H7 induced expression of proliferating cell nuclear antigen in clusters of alveolar cells in rats. Clustered cells expressed surfactant apoproteins and cytokeratin 19. These data suggest that endogenous PTHRP-(1-34) inhibits proliferation of type II cells in vivo and in vitro.

Animals↗
PubMed1997

Two-site immunofluorometric assay of intact salmon calcitonin with improved sensitivity.

We recently developed a two-site immunofluorometric assay (IFMA) of salmon calcitonin (SCT) by DELFIA (dissociation enhancement lanthanide fluoroimmunoassay) technique using the same polyclonal antibodies both for "catching" the antigen and for signaling. In the present study we used a monoclonal antibody to SCT 1-11 as the capture antibody. This antibody was biotinylated before use in streptavidin-coated microtitration plates. The polyclonal antibody labeled with Eu chelate was used as a signaling marker. This combination of antibodies resulted in an assay that was three to four times more sensitive than the previous IFMA, with a detection limit of 0.3 pmol/L serum. Intact SCT 1-32 was detected by the assay (recoveries 94-96%), but not the fragments SCT 1-11 and SCT 10-32 or human calcitonin. Dilutions of plasma samples containing SCT were parallel to the calibration curve of SCT 1-32. Pharmacokinetic studies of SCT, 100 IU administered intramuscularly to 10 men, indicated peak serum concentrations of 32-128 pmol/L within 10-20 min with apparent half-life of 56+/-18 min (mean+/-SD). This new assay will allow study of the pharmacokinetics of new calcitonin preparations that do not require injection.

Adult↗
PubMed1996

Transcriptional regulation of the human chromogranin A gene by its 5' distal regulatory element: novel effects of orientation, structure, flanking sequences, and position on expression.

In previous studies of human chromogranin A (hCgA) gene expression, we had identified a 27 bp distal regulatory element (DRE) located between -576 and -550 bp that interacts with a CRE-containing promoter to enhance gene transcription specifically in neuroendocrine (NE) cells. To characterize the DRE we have now mutated its various parts and assessed the effects on protein binding by electrophoretic mobility shift assays (EMSAs) and hCgA transcription within BEN cells. We found that the sequence TGACTAA, an AP-1 binding site that we refer to as DRE-AP-1, was necessary but not sufficient to produce the DRE's enhancer effect. Moreover, while AP-1 (Jun/Fos) bound this site, binding was not correlated with transcriptional effects. Protein binding by the DRE-AP-1 could be attenuated by mutations of its flanking sequences, and transcriptional enhancement by the DRE was dependent on its orientation and spatial relationship to the hCgA proximal promoter. Mutation of the DRE-AP-1 to a consensus AP-1 did not produce greater transcriptional activity, even though it increased binding of nuclear factors. Co-transfection with c-jun and/or c-fos expression plasmids showed that the DRE was unresponsive to the over-expressed AP-1 proteins. Co-transfection with wild-type DRE oligonucleotides competitively inhibited DRE-mediated transcription, while co-transfection with mutant DRE oligonucleotides had a lesser effect. Our studies indicate that transcriptional enhancement of hCgA by the DRE is dependent on a unique NE-specific DRE-binding factor, which we refer to as DBF, that specifically and directionally binds the DRE to assemble and synergize a functional transcription complex.

Base Sequence↗
PubMed1996

Parathyroid hormone--related protein (PTHrP) is an epidermal growth factor-regulated secretory product of human prostatic epithelial cells.

Parathyroid hormone-related protein (PTHrP) has previously been shown to be expressed in human prostatic tissue and in prostatic cancer cell lines. In the present study, PTHrP immunoreactivity was detected in the glandular epithelium of normal prostate and benign prostatic hyperplasia (BPH), as well as in prostatic adenocarcinoma (CaP). Epithelial cell cultures derived from normal, BPH, and CaP tissues were also stained by antibodies against PTHrP, and northern analysis revealed multiple transcripts of PTHrP in the cellular RNA. PTHrP (1-34) was measurable by radioimmunoassay (RIA) in media conditioned by the prostatic epithelial cell cultures, and PTHrP accumulated in conditioned media during a 72 hr time course. Addition of complete growth medium to starved cells resulted in increased PTHrP mRNA levels by 1 hr, with maximal stimulation at 8-24 hr. Several individual factors contained in the complete growth medium were tested for their ability to regulate PTHrP expression. Epidermal growth factor (EGF) was the major inducer of PTHrP expression, while cholera toxin, bovine pituitary extract, hydrocortisone, and insulin had minimal or no effect on PTHrP transcript levels. Since each of these factors is growth stimulatory, the unique ability of EGF to induce PTHrP is apparently unrelated to mitogenicity. 1,25-Dihydroxyvitamin D3[1,25(OH)2D3], an inhibitor of PTHrP expression in several other cell types, had no effect on steady-state levels of PTHrP mRNA expressed by epithelial cells in complete growth medium, although prostate cells have vitamin D receptors and are responsive to 1,25(OH)2D3 in other ways. Our results indicate that PTHrP expression is not confined to the neuroendocrine cells of the human prostate and that our culture system can be used as a model to investigate the role of PTHrP in the prostate.

Adenocarcinoma↗
PubMed1996

Hypercalcemia and systemic lupus erythematosus.

Hypercalcemia is commonly caused by the increased production of parathyroid hormone-related protein (PTHrP) by a malignancy. In fact, the demonstration of increased PTHrP production in a patient with hypercalcemia is virtually pathognomonic of malignancy. We studied a patient with systemic lupus erythematosus (SLE), generalized lymphadenopathy, and hypercalcemia. Immunohistology of 2 biopsied lymph nodes revealed the abundant expression of PTHrP and the absence of malignant transformation. Although apparently rare, PTHrP production by non-malignant lymphoid tissue may occur in SLE and should be considered in the differential diagnosis of hypercalcemia.

Adult↗
PubMed1996

Expression of the nucleoside triphosphate pyrophosphohydrolase PC-1 is induced by basic fibroblast growth factor (bFGF) and modulated by activation of the protein kinase A and C pathways in osteoblast-like osteosarcoma cells.

The closely related cytokines bFGF and aFGF regulate the function of bone cells and mineralization. Osteoblasts express PPi-generating nucleoside triphosphate pyrophosphohydrolase (NTPPPH)/nucleotide phosphodiesterase I activity. bFGF and aFGF (10 ng/ml) up-regulated NTPPPH in human SaOS-2 and U2OS osteosarcoma cells, which express osteoblast-like features in culture. The induction was selective as alkaline phosphatase activity was down-regulated and specific as insulin-like growth factor-1 (IGF-1) and interleukin-1 beta (IL-1 beta) were not active. Furthermore, IL-1 beta but not IGF-1 inhibited bFGF-induced up-regulation of NTPPPH. The induced NTPPPH remained predominantly associated with cells. bFGF can induce signaling through pathways including protein kinase A (PKA) and protein kinase C (PKC)-mediated transduction. An activator of the PKA pathway (8-bromo cyclic adenosine monophosphate [cAMP]) induced NTPPPH. Furthermore, pretreatment with the PKC activator phorbol myristate acetate (PMA) (80 nM) markedly increased subsequent NTPPPH induction by both bFGF and cAMP. The PMA effect was associated with morphologic changes characterized by long, thin intercellular extensions. PKC desensitization also potentially contributed to this effect because the PKC inhibitors staurosporine and H-7 enhanced bFGF-induced and cAMP-induced NTPPPH expression in the absence of morphologic changes. We observed that bFGF induced expression of PC-1, a member of the NTPPPH gene family. The majority of NTPPPH activity was depleted by immunoadsorption using a monoclonal antibody to native human PC-1. bFGF- and aFGF-induced production of PC-1/NTPPPH in osteoblastoid cells may contribute to the effects of FGFs on bone metabolism.

Cyclic AMP-Dependent Protein Kinases↗
PubMed1996

Immunoassay and immunohistology studies of chromogranin A as a neuroendocrine marker in patients with carcinoma of the prostate.

OBJECTIVES: Neuroendocrine differentiation in carcinoma of the prostate is characterized by the expression of neuroendocrine cell products such as chromogranin A (CgA). We studied serum levels and tissue staining for CgA in prostate cancer to assess their clinical value. METHODS: In 82 patients with prostate cancer, serum specimens were obtained at diagnosis and studied by both CgA and prostate-specific antigen (PSA) immunoassays. In 43 additional patients with prostate cancer, paraffin-embedded tissue from core biopsies or transurethral resections and serum samples were studied, respectively, by immunohistology and immunoassay for CgA. RESULTS: In serum samples from the 82 patients in whom CgA and PSA levels were measured, 26 of 82 (32%) had an elevated CgA (greater than 200 ng/mL), and 36 of 82 (44%) had an elevated PSA (greater than 4.0 ng/mL). Of the patients with Stage D2 cancer, 11 of 18 (61%) had an elevated CgA and 6 of 18 (33%) had an elevated PSA. Four of 5 patients with local recurrence had an elevated CgA, but only 1 patient had an elevated PSA. Of the 43 patients in whom serum and tissue CgA studies were performed, 12 (28%) had elevated serum CgA, and 15 of the 43 (35%) had CgA staining in their prostate tissue. Of the 14 of these patients with D2 disease (distant metastases), 9 (64%) had elevated serum levels of CgA and 6 (43%) had positive staining in their prostate tissue. Of the 9 patients with Stage D2 disease and elevated serum CgA, 6 had a normal serum PSA. CONCLUSIONS: Our studies complement those of others and indicate that CgA has potential as a clinically useful serum and tumor marker for prostate cancer. Serum CgA measurements can identify some patients with advanced disease who do not have elevated serum PSA. However, further studies in larger groups of patients are needed to define the clinical value of CgA as a marker for prostate cancer.

Biomarkers, Tumor↗
PubMed1996

Calcitonin receptor mRNA expression in the human prostate.

OBJECTIVES: A subpopulation of prostate neuroendocrine (NE) cells contain calcitonin (CT). It has been postulated that CT-producing cells in the prostate account for the high CT level in the semen, and may be involved in the regulation of other epithelial cells via a paracrine mechanism. The presence of CT binding sites in the plasma membrane fraction of prostate tissue has been demonstrated by radioligand binding assay. In the present study, we investigated the CT receptor gene expression in the human prostate, a key component of the autocrine/paracrine loop in the CT functional pathway. METHODS: Reverse transcription polymerase chain reaction (RT-PCR) was carried out to evaluate the CT receptor mRNA expression in normal prostate tissue. Subsequent DNA sequencing was used to verify RT-PCR amplified products and to determine the isoform of the receptor. To define the location of the CT receptor expression, nonradioactive in situ hybridization was performed with a digoxigenin-labeled probe complementary to the coding region of the CT receptor mRNA. A polyclonal antibody against CT was used to reveal the CT-secreting cells in the prostate. RESULTS: CT receptor MRNA expression was detected in the prostate tissue. Further analysis of the DNA sequence showed that CT receptor expressed in the prostate was the isoform without a 16-amino acid insert in the first intracellular domain. In situ hybridization revealed that CT receptor was present in the prostate NE cells. Immunocytochemical staining of mirror image sections showed that some CT-secreting cells also expressed CT receptor. CONCLUSIONS: CT receptor expression in the prostate, a key component in the CT functional pathway, is located in subsets of dispersed NE cells (CT secreting and CT nonsecreting), which indicates that prostate CT may play an important role in the autocrine/paracrine regulation of the prostate NE system.

Base Sequence↗
PubMed1996

The humoral hypercalcemia of benignancy. A newly appreciated syndrome.

It has become recently appreciated that the hypercalcemia of malignancy is commonly caused by the increased production of parathyroid hormone-related protein (PTHrP) by the cancer. In fact, the demonstration of increased PTHrP production in a patient with hypercalcemia is regarded as pathognomonic of malignancy. The authors describe a patient with a benign ovarian lesion that produced PTHrP and caused hypercalcemia. They identify other reports of hypercalcemia associated with hypercalcemia and benign tumors, and refer to this syndrome as the humoral hypercalcemia of benignancy. Although apparently rare, a benign PTHrP-producing tumor should be considered in the differential diagnosis of hypercalcemia.

Adult↗
PubMed1996

Parathyroid hormone-related protein, an autocrine regulatory factor in alveolar epithelial cells.

Alveolar epithelial cells in vivo, primary cultures of adult rat type II cells, and human A549 alveolar carcinoma cells express parathyroid hormone-related protein (PTHrP). Here we demonstrated that type II cells and A549 cells also express the PTHrP receptor and that they exhibit differentiation-related responses to the amino-terminal PTHrP fragment, PTHrP-(1-34). PTHrP receptor expression in A549 cells was shown by detection of a 0.3-kb reverse transcriptase polymerase chain reaction product formed by primers specific for PTHrP receptor. In situ hybridization studies localized the site of production of PTHrP and PTHrP receptor mRNA in rat lung cells with morphology and location typical of type II cells. Primary cultures of such type II cells also expressed PTHrP receptor mRNA. Incubation with PTHrP-(1-34) stimulated disaturated phosphatidylcholine (DSPC) synthesis in A549 cells and increased the release of newly synthesized DSPC by cultured type II cells and A549 cells. In addition, PTHrP-(1-34) increased the number of lamellar bodies per type II cell and increased their expression of alkaline phosphatase in a dose-dependent manner. Thus PTHrP-(1-34) promoted a differentiated type II cell phenotype. Since cultured type II cells, alveolar epithelial cells in vivo, and A549 cells express PTHrP and the PTHrP receptor, PTHrP-(1-34) may be an autocrine regulatory factor in type II cells and lung cancer cells.

Animals↗
PubMed1996

Elimination of the carboxy-terminal sequences of parathyroid hormone-related protein 1-173 increases production and secretion of the truncated forms.

The endoproteolytic processing of polypeptides at basic residues into distinct biologically active peptides is a common theme in prohormone maturation and processing. PTH-related protein (PTHrP) 1-173 contains eight putative endoproteolytic consensus sites that include a mono-arginyl (R37), paired basic (RR154-155), and related basic residue motifs (RLKR-4 to -1, RRR19-21, KKKK88-91, KRK96-98, KKKRR102-106, and KKKK147-150). To analyze the primary structural determinants involved in the posttranslational processing and secretion of PTHrP 1-173, we constructed a series of nonsense mutants that code for carboxy-terminal truncated polypeptides. Since the basic residue motifs are probable sites of endoproteolysis, these sites and the residues downstream were serially eliminated, thereby creating PTHrP 1-152, 1-146, 1-101, 1-95, 1-87, 1-36, and 1-18. The wild type PTHrP 1-173 and nonsense mutant constructs were transiently transfected into two cell lines, COS-1 and SK-N-BE(2). The COS-1 cells have a constitutive secretory pathway, whereas the neuroblastoma-derived BE-2 cells have, in addition, a regulated secretory pathway. PTHrP was measured in the conditioned media and cell extracts of the transfected cells with two peptide-specific RIAs. In COS-1 cells, PTHrP truncation mutants 1-152, 1-146, 1-101, 1-95, and 1-87 were present relative to wild type isoform 1-173, at 4.4-, 3-, 19-, 12-, and 57-fold excess, respectively; a similar pattern was also detected with BE-2 transfected cells, although the relative increases above the quantities of PTHrP 1-173 were not as dramatic. As the carboxy-terminal sequences were eliminated, the amount of total and secreted PTHrP increased, and the percentage found within the cell decreased. In COS-1 cells, 10.5% of the total PTHrP 1-173 was intracellular, whereas only 1% of the total PTHrP 1-87 was intracellular. In BE-2 cells, 54% of the total PTHrP 1-173 and only 9% of the total 1-87 mutant were intracellular. In COS-1 cells, a time course analysis demonstrated that PTHrP 1-87 and 1-95 were detectable in media 3 h after transfection, whereas 1-173 was barely detectable after 24 h. Our studies suggest that the carboxy-terminal sequence of PTHrP 1-173 is responsible for the intracellular degradation of this polypeptide, which may be the endogenous cellular mechanism that regulates the amount of processed and secreted PTHrP.

Amino Acid Sequence↗
PubMed1996

Hypercalcemia: mechanisms, differential diagnosis, and remedies.

The urgency for treatment of hypercalcemia is assessed by determining the severity of symptoms and complications and the degree of elevation of serum calcium. Increased bone resorption is the most common pathophysiologic mechanism for hypercalcemia, and several agents are used to inhibit this resorption, including calcitonin and bisphosphonates. However, inhibition of bone resorption controls hypercalcemia for only a limited time, and prompt definitive treatment of the underlying cause, such as primary hyperparathyroidism or malignancy, is essential.

Diagnosis, Differential↗