Biomedical subjects

M Lacroix

Publications and source records attributed to M Lacroix.

At least 55 records · Page 3Linked to original sources

PubMed2000

Effect of gamma-irradiation on phenolic compounds and phenylalanine ammonia-lyase activity during storage in relation to peel injury from peel of Citrus clementina hort. Ex. tanaka.

The influence of gamma-irradiation on the content of phenolic compounds was evaluated on Moroccan Citrus fruits (Citrus clementina Hort. ex. Tanaka) treated at a mean dose of 0.3 kGy and stored for 49 days at 3 degrees C. The results show that irradiation has enhanced the synthesis of total phenolic compounds and is correlated with phenylalanine ammonia-lyase activity (PAL) during storage. Accumulation of phenolic compounds in cells is demonstrated and may be explained by the enhancement of PAL activity. HPLC/UV (diode array detector) analysis demonstrated that hesperidin was the major flavanone and nobiletin and heptamethoxyflavone were the major polymethoxylated flavones. Hesperidin is also the major phenolic compound in clementines. Irradiation stimulates the biosynthesis of hesperidin after 14 days of storage, corresponding to the maximum of PAL activity. p-Coumaric acid was also identified, and its content was particularly high in irradiated fruits after 49 days of storage. Accumulation of flavonoids and p-coumaric acid could be related to a better resistance. The percentage of losses due to peel injury "pitting" during storage was between 1 and 5% after 49 days of storage. The connections between irradiation, enzyme activity, phenolic content, and peel injury are briefly discussed.

Chromatography, High Pressure Liquid↗

PubMed2000

Mechanical and structural properties of milk protein edible films cross-linked by heating and gamma-irradiation.

The mechanical properties of cross-linked edible films based on calcium caseinate and two type of whey proteins (commercial and isolate) were investigated. Cross-linking of the proteins was carried out using thermal and radiative treatments. Size-exclusion chromatography performed on the cross-linked proteins showed that gamma-irradiation increased the molecular weight of calcium caseinate, while it changed little for the whey proteins. However, heating of the whey protein solution induced cross-linking. For both cross-linked proteins, the molecular weight distribution was >/=2 x 10(3) kDa. Combined thermal and radiative treatments were applied to protein formulations with various ratios of calcium caseinate and whey proteins. Whey protein isolate could replace up to 50% of calcium caseinate without decreasing the puncture strength of the films. Films based on commercial whey protein and calcium caseinate were weaker than those containing whey protein isolate. Electron microscopy showed that the mechanical characteristics of these films are closely related to their microstructures.

Gamma Rays↗

PubMed2000

Protein production by osteoblasts: modulation by breast cancer cell-derived factors.

Breast cancer cells (BCC) frequently metastasize to bone where they may cause tumor-induced osteolysis (TIO). While the important eroding role of the osteoclasts in TIO is well admitted, the possibility that BCC and/or osteoblasts activated by tumoral factors could also directly degrade bone matrix in this pathology has been much less investigated. We show here that the net collagen amount produced in vitro by normal human osteoblasts and osteoblast-like cells was significantly reduced by culture medium conditioned by several BCC lines, including three newly isolated ones. There was no evidence for a decrease in collagen synthesis, as assessed by the production of the carboxyterminal propeptide of type I collagen. In contrast, the effect of BCC-derived medium on collagen amount was attenuated by inhibitors of matrix metalloproteinases (MMPs) as well as by tranexamic acid, an inhibitor of the plasminogen conversion to plasmin, while it was abolished in presence of the two kinds of proteinase inhibitors. This osteoblastic protein degradation activity appeared to be attributable to factors secreted by the osteoblasts as well as by BCC. These factors had molecular weights lower as well as higher than 10 kD. Our data suggest that besides the eroding action of osteoclasts, BCC- and osteoblast-derived MMPs and serine proteinases might play a direct role in bone collagen degradation in TIO.

Adenocarcinoma↗

PubMed2000

An implantable guide-screw system for brain tumor studies in small animals.

OBJECT: To overcome the problems associated with using stereotactic techniques to establish intracranial xenografts in nude mice and to treat engrafted tumors with intratumoral therapies (such as gene or viral therapies), the authors developed an implantable guide-screw system. In this study, they describe the guide-screw system, its method of implantation, and their experience with establishing xenografts and delivering intratumoral therapy. METHODS: The system consists of a 2.6-mm guide screw with a central 0.5-mm diameter hole that accepts the 26-gauge needle of a Hamilton syringe. The screw is implanted into a small drill hole made 2.5 mm lateral and 1 mm anterior to the bregma. A stylet is used to cap the screw between treatments. Tumor cells or therapeutic agents are injected in a freehand fashion by using a Hamilton syringe and a 26-gauge needle fitted with a cuff to determine the depth of injection. To test this system, guide screws were successfully implanted in 44 (98%) of 45 nude mice. After 1 to 2 weeks of recovery, 38 mice were inoculated with U87MG cells and killed 5 days later. On histological studies in 37 (97%) of these animals, xenografts were evident within the caudate nucleus (mean diameter 2.5 mm). To determine whether injections into the center of an established xenograft could be reproducibly achieved with the guide-screw system, an adenovirus vector containing the beta-galactosidase gene was injected 3 days after cell implantation in 15 of the mice. All of these animals demonstrated transduced cells within the tumor. To demonstrate that engrafted animals have a uniform survival time that is indicative of reproducible tumor growth, the survival of six mice was assessed after engraftment with U87MG cells. All six animals died within 28 to 35 days. CONCLUSIONS: The guide-screw system allows a large number of animals to be rapidly and reproducibly engrafted and for intratumoral treatments to be accurately delivered into established xenografts.

Animals↗

PubMed1999

The N-terminal CUB-epidermal growth factor module pair of human complement protease C1r binds Ca2+ with high affinity and mediates Ca2+-dependent interaction with C1s.

The Ca2+-dependent interaction between complement serine proteases C1r and C1s is mediated by their alpha regions, encompassing the major part of their N-terminal CUB-EGF-CUB (where EGF is epidermal growth factor) module array. In order to define the boundaries of the C1r domain(s) responsible for Ca2+ binding and Ca2+-dependent interaction with C1s and to assess the contribution of individual modules to these functions, the CUB, EGF, and CUB-EGF fragments were expressed in eucaryotic systems or synthesized chemically. Gel filtration studies, as well as measurements of intrinsic Tyr fluorescence, provided evidence that the CUB-EGF pair adopts a more compact conformation in the presence of Ca2+. Ca2+-dependent interaction of intact C1r with C1s was studied using surface plasmon resonance spectroscopy, yielding KD values of 10.9-29.7 nM. The C1r CUB-EGF pair bound immobilized C1s with a higher KD (1.5-1.8 microM), which decreased to 31.4 nM when CUB-EGF was used as the immobilized ligand and C1s was free. Half-maximal binding was obtained at comparable Ca2+ concentrations ranging from 5 microM with intact C1r to 10-16 microM for C1ralpha and CUB-EGF. The isolated CUB and EGF fragments or a CUB + EGF mixture did not bind C1s. These data demonstrate that the C1r CUB-EGF module pair (residues 1-175) is the minimal segment required for high affinity Ca2+ binding and Ca2+-dependent interaction with C1s and indicate that Ca2+ binding induces a more compact folding of the CUB-EGF pair.

Animals↗

PubMed1999

Dose rate effect of gamma irradiation on phenolic compounds, polyphenol oxidase, and browning of mushrooms (Agaricus bisporus).

To enhance the shelf life of edible mature mushrooms, Agaricus bisporus, 2 kGy ionizing treatments were applied at two different dose rates: 4.5 kGy/h (I(-)) and 32 kGy/h (I(+)). Both I(+) and I(-) showed a 2 and 4 day shelf-life enhancement compared to the control (C). Before day 9, no significant difference (p>0.05) in L value was detected in irradiated mushrooms. However, after day 9, the highest observed L value (whiteness) was obtained for the mushrooms irradiated in I(-). Analyses of phenolic compounds revealed that mushrooms in I(-) contained more phenols than I(+) and C, the latter containing the lower level of phenols. The fluctuation of the precursors of glutaminyl-4-hydroxyaniline (GHB) was less in I(-) than in I(+). The polyphenol oxidase (PPO) activities of irradiated mushrooms, analyzed via catechol oxidase, dopa oxidase, and tyrosine hydroxylase substrates, were found to be significantly lowered (p = 0.05) compared to C, with a further decrease in I(+). Analyses of the enzymes indicated that PPO activity was lower in I(+), contrasting with its lower phenols concentration. The observation of mushrooms' cellular membranes, by electronic microscopy, revealed a better preserved integrity in I(-) than in I(+). It is thus assumed that the browning effect observed in I(+) was caused by both the decompartmentation of vacuolar phenol and the entry of molecular oxygen into the cell cytoplasm. The synergetic effect of the residual active PPO and the molecular oxygen, in contact with the phenols, allowed an increased oxidation rate and, therefore, a more pronounced browning I(+) than in I(-).

Agaricales↗

PubMed1998

Establishment and characterization of three new breast-cancer cell lines.

We have established and characterized 3 new breast-cancer cell lines from pleural effusions of patients with advanced breast cancer. All 3 cell lines, designated IBEP-1, IBEP-2 and IBEP-3, showed typical ultrastructural characteristics of epithelial mammary tumor cells. Electron microscopy showed, among other characteristics, the presence of numerous microvilli, desmosomal junctions, intracytoplasmic duct-like vacuoles, well-developed endoplasmic reticulum and large nuclei. Immunohistochemical and biochemical studies revealed that the 3 cell lines expressed cytokeratin, epithelial membrane antigen, CEA and CA 15-3, but all showed negative immunoreaction for vimentin. On the other hand, other antigens (LEU-M1, GCDFP 15, c-erbB-2) were expressed by some of the cell lines, but in a variable manner. Ploidy studies confirmed the neoplastic origin of the cell lines. The doubling times were 68 hr for IBEP-1, 29 hr for IBEP-2 and 39 hr for IBEP-3. Only IBEP-2 cells expressed estrogen receptors (ER+), which were down-regulated after preincubation with E2, but they did not express progesterone receptors (PgR-). IBEP-1 and IBEP-3 cells were ER- but expressed PgR (PgR+). In these 2 cell lines, PgR were down-regulated after pre-incubation of the cells with progesterone (10(-8) M) for 24 hr. Estradiol (E2) increased the proliferation rate of IBEP-2 cells and progesterone increased the proliferation of IBEP-I and -3 cell lines. S.C. injection of the 3 IBEP cell lines into nude mice resulted in the growth of solid tumors between 11 and 16 weeks after inoculation. These cell lines could thus be new models for studying various aspects of the biology and the tumorigenicity of breast-cancer cells. A major interest of these new cell lines is that 2 of them were ER- and PgR+, which is an exceptional phenotypic feature. These 2 cell lines could be interesting models for studying the regulation of PgR and the effects of progestins and antiprogestins independently of the presence of ER.

Aged↗

PubMed1998

Production and regulation of interleukin-11 by breast cancer cells.

We have studied the production of interleukin-11 (Il-11) in 13 breast cancer cell (BCC) lines. Two of these cell lines (MDA-MB-231 and Hs578T) expressed the cytokine at both the protein and mRNA levels. Il-11 did not modulate the growth of five BCC lines examined, including the two cytokine-producing BCC lines. The production of Il-11 was increased by transforming growth factor-beta1 in a dose-dependent manner with a rapid (2 h) and transient (24 h) mRNA induction, but not by epidermal growth factor, insulin-like growth factor-I and -II, basic fibroblast growth factor, platelet-derived growth factor or parathyroid hormone. The cyclic AMP inducer, forskolin, and the activator of protein kinase C, phorbol 12-myristate 13-acetate, also stimulated the production of Il-11. Besides Il-11, MDA-MB-231 and Hs578T were the only BCC lines to produce interleukin-6 (Il-6) protein and mRNA. Since Il-11 and Il-6 are potent stimulators of osteoclast development and bone is a major source of TGF-beta1, our data suggest that Il-11, together with Il-6, contributes to the high bone destructive capacity of MDA-MB-231 cells and could play a role in breast cancer-induced osteolysis.

Breast Neoplasms↗

PubMed1998

Breast cancer cell response to calcitonin: modulation by growth-regulating agents.

Calcitonin may induce cyclic AMP production by breast cancer cells and inhibit their growth. The molecular complex leading to cyclic AMP production in response to calcitonin is made of the calcitonin receptor coupled to the adenylate cyclase by at least one guanine nucleotide-binding protein (G-protein, of the Gs type). Our aim was to determine whether and how the responses of cells to calcitonin were modulated by growth-regulating agents not directly acting through the cyclic AMP pathway. We found that the cyclic AMP response to calcitonin was reduced after preincubation of cells with the mitogens 17beta-estradiol and epidermal growth factor (EGF), while it was enhanced after preincubation with the growth inhibitors tamoxifen and 1,25(OH)2D3, as well as with an antisense oligonucleotide to the proto-oncogene c-myc. Scatchard-plots revealed no significant change in the calcitonin receptor number or affinity. On the other hand, the cyclic AMP production of cells in response to activators unrelated to calcitonin, such as forskolin, a direct adenylate cyclase effector, and isoproterenol, a beta-adrenergic receptor agonist, was modulated only weakly or not at all by the growth-regulating agents. This suggested that the effects observed were essentially calcitonin-specific and associated with events located between the calcitonin receptor and the adenylate cyclase. Since a Go- or Gi-protein has been previously implicated in the calcitonin signal transduction, we tested the action of pertussis toxin, a specific inhibitor of these G-proteins. Pertussis toxin produced a general increase in the cyclic AMP response of cells to calcitonin; moreover, the toxin almost abolished the effect of mitogens and antimitogens on that parameter. We conclude that in breast cancer cells, the calcitonin receptor and the adenylate cyclase are coupled by at least one Go/Gi-protein sensitive to growth-regulating agents; this results in a modulation of the cyclic AMP response to calcitonin by these agents. On the other hand, the growth-inhibitory effect of calcitonin on breast cancer cells was reduced by 17beta-estradiol and enhanced by tamoxifen. We suggest that this could be a consequence of changes in cyclic AMP levels and deserves further investigation.

Breast Neoplasms↗

PubMed1998

Formation of Sterilized Edible Films Based on Caseinates: Effects of Calcium and Plasticizers.

gamma-Irradiation was used to produce free-standing sterilized edible films based on caseinate. The effects of calcium ions (Ca(2+)) and two plasticizers, namely propylene glycol (PG) and triethylene glycol (TEG), were investigated, as was the effect of the irradiation on both the gel formation and mechanical properties of the resulting films. gamma-Irradiation provoked formation of bityrosine, i.e., cross-links, accounting for the increase of the puncture strength of films. The presence of PG or TEG enhanced the formation of cross-links, leading to an improved mechanical strength of films. TEG was found to interact more favorably with the caseinate than PG, being responsible for the improved film extensibility. Addition of Ca(2+) caused the formation of gels. The breaking strength of gels was directly related to the concentration of Ca(2+), while the puncture strength of films was found to be almost independent of the calcium concentration. Moreover, a high irradiation dose seemed to affect the protein structure, accounting for the decrease of the breaking strength of gels and for the depreciation of the mechanical behavior of films.

Journal Article↗

PubMed1998

Biodegradability behavior of cross-linked calcium caseinate films

gamma-Irradiation was used to produce free-standing biodegradable caseinate films. The effect of the irradiation dose (i.e., the number of cross-links) on the biodegradability behavior of these films using a strain of Pseudomonas aeruginosa was investigated. Results showed that the overall degradation processes were similar for both types of films (4 or 64 kGy). The main difference was observed in terms of the period of degradation which was delayed 8 days for the film containing the highest extent of cross-linking (64 kGy).

Journal Article↗

PubMed1998

Point mutation of a rubella virus E1 protein T-cell epitope by substitution of single amino acid reversed the restrictive HLA-DR polymorphism: a possible mechanism maintaining HLA polymorphism.

The influence of single amino acid substitutions within a rubella E1 protein T-cell epitope, E1(273-284) on T-cell recognition was studied. Substitutions of an uncharged amino acid A for an E or for a T and substitution of a T for S were found to not significantly reduce the T-cell responses. However, substitution of a charged residue such as E for hydrophobic residues (I, V, or W); D for Q; or a relatively larger size amino acid for polar residues completely abolished the cytotoxicities mediated by E1(273-284)-specific T-cell clone. A set of single amino acid-substituted peptide analogs of E1(273-284) not eliciting cytotoxicity of the T-cell clone was used to test the influence of point mutation of the epitope on HLA DR restrictions. A panel of B-cell lines with different DR4 subtypes was used as targets in cytotoxicity assays to determine the restrictive HLA molecules. Results showed that modification of the T-cell epitope by point mutation could reverse the HLA DR restriction from one allele to other alleles. A model based on these results has been proposed to explain the mechanism balancing major histocompatibility complex (MHC) polymorphism in outbred populations.

Amino Acid Substitution↗

PubMed1997

Estrogen receptor-negative/progesterone receptor-positive Evsa-T mammary tumor cells: a model for assessing the biological property of this peculiar phenotype of breast cancers.

In 1986 we reported the appearance of a progestin binding protein in the human breast cancer cell line Evsa-T, originally described as lacking both estrogen and progesterone receptors (ER and PR). In this report we show that PR of this cell line displays a binding affinity for [3H]ORG 2058 and a sucrose gradient sedimentation profile similar to those ascribed to PR from MCF-7 or T47D breast cancer cell lines. PR from Evsa-T cells is down-regulated by the progestin R-5020 as well as by the two antiprogestins, ZK 112.993 and ZK 98.299, but does not confer growth sensitivity to these compounds. ER remains undetectable by ligand binding assay, enzyme immunoassay and northern blotting. Our Evsa-T clone could be a valuable model for assessing the mechanisms leading the ER-/PR+ phenotype occurring occasionally in breast cancers and frequently in meningiomas.

Breast Neoplasms↗

PubMed1997

Structure and assembly of the catalytic region of human complement protease C1r: a three-dimensional model based on chemical cross-linking and homology modeling.

C1r is the modular serine protease responsible for autocatalytic activation of C1, the first component of the complement classical pathway. Its catalytic region is a noncovalent homodimer of two gamma-B monomers, each comprising two contiguous complement control protein (CCP) modules, IV and V [also known as short consensus repeats (SCRs)], a 15-residue intermediary segment, and the serine protease B domain. With a view to gain insight into domain-domain interactions within this region, fragment C1r (gamma-B)2, obtained by autolytic proteolysis of the active protease, was cross-linked with the water-soluble reagent 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide. Cross-linked species gamma-B intra and gamma-B inter, containing intra- and intermonomer cross-links, respectively, were isolated and then fragmented by CNBr cleavage and trypsin digestion. N-Terminal sequence and mass spectrometry analyses of the resulting cross-linked peptides allowed us to identify one intramonomer cross-link between Lys426 of module V and the C-terminal Asp688 of the serine protease B domain and one intermonomer cross-link between the N-terminal Gly280 of fragment gamma and Glu493 of the B domain. Three-dimensional homology modeling of the CCP modules IV and V and of the B domain was also performed. The complementary information provided by chemical cross-linking and homology modeling studies was used to construct a three-dimensional model of the gamma-B monomer, in which module V interacts with the serine protease on the side opposite to both the active site and the Arg446-Ile447 activation site. Also, a tentative three-dimensional model of the (gamma-B)2 dimer was built, indicating a loose "head to tail" association of the monomers, with the active sites facing opposite directions toward the outside of the dimer. The latter model is compared with available low-resolution structural data, and its functional implications are discussed in terms of the conformational changes occurring during C1r activation.

Amino Acid Sequence↗

PubMed1997

Regulation of c-fos and c-jun expression by calcitonin in human breast cancer cells.

Breast cancer cells (BCC) have calcitonin (CT) receptors, yet the action of the hormone on these cells is largely unknown. We found that CT produced a strong and transient time- and dose-dependent increase in c-fos mRNA in BCC lines. This event was prevented by a protein kinase A (PKA) inhibitor, H89. CT alone did not influence the expression of c-jun and of the tissue inhibitors of metalloproteases (timp) -1 and -2 mRNAs; however, it reduced the induction of these mRNAs by the protein kinase C (PKC) activator phorbol 12-myristate 13-acetate (PMA), without apparent changes in the half-life of the mRNA (measured for c-jun). Along the same line, CT reduced the c-jun induction and T-47D growth stimulation by epidermal growth factor (EGF) and insulin. These effects were mimicked by forskolin and/or prevented by H89, suggesting that PKA activation was involved. These results indicate that CT modulates in BCC the mRNA levels of two important growth-related early response genes (c-fos and c-jun) and of two other genes (timp-1 and -2) involved in the control of metastatic events.

Blotting, Northern↗

PubMed1997

Pharmacokinetics of mivacurium isomers and their metabolites in healthy volunteers after intravenous bolus administration.

BACKGROUND: Previous studies report the pharmacokinetics of mivacurium isomers after an infusion using venous blood sampling. Although the extent of the mivacurium arterial-venous gradient is not known, the sampling site is likely to influence mivacurium pharmacokinetic parameters because the drug is rapidly metabolized as it traverses the circulation. The objectives of this study were (1) to determine the pharmacokinetics of mivacurium isomers in healthy persons after intravenous bolus administration using intensive arterial blood sampling, and (2) to characterize the formation and elimination of mivacurium metabolites in human plasma. METHODS: Eight persons classified as American Society of Anesthesiologists physical status 1 or 2 who were scheduled to undergo elective surgery under balanced anesthesia received 0.15 mg/kg mivacurium chloride as an intravenous bolus. Arterial blood samples were collected every 10 s during the first 2 min and at frequent intervals for 4 h thereafter. Plasma concentrations of mivacurium isomers and their metabolites were determined by two stereoselective high-performance liquid chromatographic methods coupled with fluorometric detection and noncompartmental pharmacokinetic parameters. RESULTS: Mean elimination half-lives of the trans-trans, cis-trans, and cis-cis isomers were 2.4, 2, and 28.5 min, respectively, with corresponding mean plasma clearances of 29.2, 45.7, and 6.7 ml.min 1.kg-1. The volumes of distribution at steady state of the trans-trans, cis-trans, and cis-cis isomers were 0.047, 0.054, and 0.189 l/kg, respectively. Plasma concentrations of monoester and alcohol metabolites peaked 25 s (median) after mivacurium injection, with half-lives in the range of 90 min, except for the cis alcohol metabolite, which was only negligibly and transiently formed. CONCLUSIONS: Substantial hydrolysis of mivacurium isomers by cholinesterases was confirmed by the rapid appearance of mivacurium metabolites in plasma. The intensive arterial sampling proved to be critical for the trans-trans and cis-trans isomers because the area under the curve between 0 and 2 min accounted for 75% and 86% of the total, respectively.

Adolescent↗

PubMed1997

Secretory products of breast cancer cells specifically affect human osteoblastic cells: partial characterization of active factors.

The pathogenesis of tumor-induced osteolysis (TIO) following breast cancer metastases in bone remains unclear. We postulated that osteoblasts could be target cells for the secretory products of breast cancer cells. We previously showed that serum-free conditioned medium (CM) of the breast cancer cell line MCF-7 inhibits DNA synthesis by 75% of control values in osteoblast-like cells SaOS-2 and that this effect is only in a minor part due to transforming growth factor beta secretion. To establish the specificity of our observations and to look for other biologically active factors, we have tested the effects of medium conditioned by several cancer and noncancer cell lines (breast, colon, placenta, or fibrosarcoma) on the proliferation of osteoblast-like cells (SaOS-2, MG-63), normal human osteoblasts, human fibrosarcoma cells, and normal human fibroblasts. Culture medium (1:2) of the breast cancer cell lines MCF-7, T-47D, MDA-MB-231, and SK-BR-3 inhibited by 25-50% the proliferation of osteoblast-like cells SaOS-2, MG-63, and normal osteoblasts as evaluated by the MTT survival test or [3H]thymidine incorporation. MCF-7 cells completely inhibited the proliferation of normal human osteoblasts in coculture. This inhibitory effect was reversible and not due to cytotoxicity. Moreover, the cyclic adenosine monophosphate (cAMP) response to parathyroid hormone (PTH) of osteoblast-like cells SaOS-2 was also increased by 100-240% by the same CM. Such activities were, however, not detected in medium from the breast noncancer cell line HBL-100 or in the medium conditioned by non-breast cancer cell lines (COLO 320DM, HT-29, JAR, or HT-1080). Medium from the breast cancer cells had no effect on normal human fibroblasts or fibrosarcoma cells (HT-1080), suggesting the specificity of their action on human osteoblasts. After partial purification by ultrafiltration and size-exclusion chromatography, we found that medium of T-47D cells contained at least three nonprostanoid factors of low molecular weights (apparent MW of 700, 1500, and 4000 D) which affected human osteoblast-like cells. These factors were heat stable and could be peptides without disulfide bonds. In summary, our data show that human breast cancer cells release soluble factors that inhibit osteoblast proliferation and increase their cAMP response to PTH, indicating that osteoblasts could be important target cells for breast cancer cells and could be involved in the process of TIO.

Breast Neoplasms↗

PubMed1997

Predictive patterns of suicidal behavior: the United States armed services versus the civilian population.

Suicide is the eighth leading cause of death in the United States and the third leading cause of death in the military population. The purpose of this study was to compare the suicide rates of the Army, Navy, Marine Corps, and Air Force to the U.S. population for the years 1980 through 1992. Multivariate linear regression analytic techniques were used to test the specific effects of year, service membership, and gender on suicide rates. A hierarchical linear regression equation resulted in R2 = 0.6737, a highly predictive finding (F112,18 = 13.600, p < 0.000). Further controlled hypothesis testing suggested that each independent variable provided a unique contribution to the total variance accounted for in suicide rates. A follow-on set of time series regressions was used to assess the effects of gender and specific military service on suicide rates over the 13-year period. Findings revealed that suicide rates for civilian males are increasing, whereas civilian female rates are declining. No significant trends by year were shown among the services. Military suicide rates were consistently lower than civilian rates, and military female rates tended to be lower yet than military male rates.

Feasibility Studies↗