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Biomedical subjects

M J Hendrix

Publications and source records attributed to M J Hendrix.

At least 55 records · Page 3Linked to original sources
PubMed1998

The Virtual Naval Hospital: a digital library for naval primary care providers and patients.

OBJECTIVE: To deliver optimal patient care and promote wellness, naval providers and patients require convenient access to medical information from isolated duty stations. The Internet can lower barriers to accessing information. The goal of this study was to determine the technical feasibility of using the Internet to deliver medical information to isolated naval points of care. METHODS: A digital library for naval primary care providers and patients with an integrated, problem-based interface was developed. The Virtual Naval Hospital (http:/(/)www.vnh.org) was evaluated from sea, undersea, and shore. RESULTS: The digital library was a popular resource. Access to it is currently limited because few ships have Internet access. CONCLUSIONS: The technical feasibility of delivering a digital library of medical information to the deckplates was proven. The digital library will realize its potential when satellite-based access to the Internet becomes available. In the interim, the digital library will also be distributed on CD-ROM.

CD-ROM↗
PubMed1997

Quality indicators for primary mental health within managed care: a public health focus.

Primary mental health is an orientation to care that addresses mental health needs of consumers on point of first contact with caregivers. Core values, and principles drawn from a public health perspective serve as the foundation for indicators of quality within managed primary mental health. A model, illustrating the key components for quality indicators, includes stakeholder groups (consumers, families, providers, and payers), quality concerns (access, appropriateness, outcomes, and prevention), and the spectrum of clinical processes (assessment, treatment, rehabilitation, and support). Responsibility for monitoring quality is vested in these stakeholder groups. To enable them to fulfill their responsibilities, indicators are proposed in the form of checklists. The checklists assist stakeholders in evaluating the plans and services offered by managed care entities.

Community Mental Health Services↗
PubMed1997

Selection of invasive and metastatic subpopulations from a human lung adenocarcinoma cell line.

To better understand the mechanism(s) underlying lung cancer invasion and metastasis, a Transwell invasion chamber was used to select progressively more invasive cancer cell populations from a clonal cell line of human lung adenocarcinoma, CL1. Five sublines with progressive invasiveness, designated CL1-1, CL1-2, CL1-3, CL1-4, and CL1-5, were obtained through this in vitro selection process. Their invasive abilities through basement membrane matrix showed a 4- to 6-fold increase over that of the parental cells. Moreover, the sublines manifested an increase in their colony-forming ability on soft agar, tumorigenicity, and metastatic potency in severe combined immunodeficiency (SCID) mice. Examining the phenotypes of the cell lines revealed increased expression of 92 kD gelatinase and an increase in the cell population stained with anti-keratin-8 and -18 antibodies. Clonal isolation of anti-keratin-18-antibody-positive and -negative cell populations demonstrated a correlated enhancement of the invasiveness of these cells and their expression of keratin-18. These results support the notion that the metastatic behavior of lung cancer cells can be characterized with this in vitro system, and that the properties of these progressively invasive cancer cells can be clonally studied.

Adenocarcinoma↗
PubMed1997

Experimental co-expression of vimentin and keratin intermediate filaments in human breast cancer cells results in phenotypic interconversion and increased invasive behavior.

The expression of intermediate filament proteins is remarkably tissue specific, which suggests that the intermediate filament type(s) present in cells is somehow related to their biological function. However, in some cancers, particularly malignant breast carcinoma, there is a strong indication that vimentin is co-expressed with keratins, thus presenting as a dedifferentiated or interconverted (between epithelial and mesenchymal) phenotype. In the present study, we recapitulated the interconverted phenotype by developing stable transfectants of MCF-7 human breast cancer cells, termed MoVi clones, to express both vimentin and keratins. Overexpression of vimentin in these cells led to augmentation of motility and invasiveness in vitra. These activities could be transiently down-regulated by vimentin antisense oligonucleotides in MoVi clones and MDA-MB-231 cells (which constitutively co-express keratins and vimentin). Furthermore, in the MoVi experimental transfectants expressing the highest percentage of vimentin-positive cells, their proliferative capacity, clonogenic potential, and tumorigenicity increased. However, the metastatic ability of the MoVi transfectants remained unchanged compared with MCF-7neo controls. The MDA-MB-231 cells metastasized to axillary lymph nodes in a SCID mouse model. Finally, we explored the possibility that potential changes could occur with respect to cell surface integrins. These studies revealed a decrease in the alpha 2- and alpha 3-containing promiscuous integrins, in addition to beta 1 containing integrins, concomitant with an increase in the alpha 6-containing laminin receptor integrin. Further functional analysis of the alpha 6 observation showed an increase in the baptotactic migration of MoVi transfectants toward a laminin substrate. From these data, it is postulated that the ability to co-express vimentin and keratins confers a selective advantage to breast cancer cells in their interpretation of signaling cues from the extracellular matrix; however the addition of vimentin intermediate filaments alone is not sufficient to confer the metastatic phenotype.

Animals↗
PubMed1997

Induction of invasive and degradative phenotype in normal synovial fibroblasts exposed to synovial fluid from patients with juvenile rheumatoid arthritis: role of mononuclear cell population.

OBJECTIVE: To investigate the effect of synovial fluid (SF) from patients with juvenile rheumatoid arthritis (JRA) on proliferation and induction of degradative and invasive phenotype in normal synovial fibroblasts, and to elucidate the contribution of SF cells to this activity. METHODS: SF and/or conditioned medium (CM) from SF cells were evaluated for their ability to (1) stimulate a proliferative response, (2) induce the "activated phenotype" capable of invading cartilage matrix, and (3) promote the release of key matrix metalloproteinases (MMP) in normal synovial fibroblasts. RESULTS: Proliferation of normal synovial fibroblasts exposed to SF or CM from SF cells of patients with JRA was up to 3 times greater than untreated controls. Concomitant with induction of an activated phenotype in the treated synovial fibroblasts, the activated form exhibited up to 250% invasiveness of cartilage matrix compared to untreated synovial fibroblasts (100%), in addition to releasing increased MMP activity, not normally associated with these quiescent cells. This induction was not solely due to tumor necrosis factor-alpha, transforming growth factor-beta, interleukin 1beta (IL-1beta), and IL-6, as SF and/or CM depleted of these cytokines sustained about 40% of their invasive and inducing ability. We observed that the mononuclear cell (MNC) population that infiltrated into the joint cavity secretes this "inducing activity," which can be maintained in culture up to several weeks. CONCLUSION: Our data suggest that the cellular component of SF releases soluble factor(s) that directly or indirectly contribute to (a) proliferation of synovial fibroblasts, and (b) production and release of extracellular MMP by synovial fibroblasts, thereby inducing a degradative and invasive phenotype culminating in cartilage and bone destruction.

Antibodies↗
PubMed1997

Maspin. A tumor suppressing serpin.

Maspin, a serpin found in mammary epithelial cells, has been shown to have tumor suppressor activity. The gene is expressed in normal human mammary epithelial cells but down-regulated in invasive breast carcinomas. Similar patterns of expression at the RNA and protein levels are seen by Northern analysis with cells grown in culture and by immunostaining of tissues. Biological assays of invasion by tumor cells through Matrigel membranes and of motility have shown that recombinant maspin inhibits both processes, and that its inhibitory action is totally lost by a single cleavage at the reaction center. Tumor transfectants expressing maspin are inhibited in growth and metastasis in nude mice. Maspin is located in the cell membrane and extracellular matrix, and does not behave as a classical inhibitory serpin against any known target protease. Its mode of action is presently unknown.

Amino Acid Sequence↗
PubMed1996

Maspin acts at the cell membrane to inhibit invasion and motility of mammary and prostatic cancer cells.

Maspin, a novel serine protease inhibitor (serpin), inhibits tumor invasion and metastasis of mammary carcinoma. We show here that recombinant maspin protein blocks the motility of these carcinoma cells in culture over 12 h, as demonstrated by time-lapse video microscopy. Lamellopodia are withdrawn but ruffling continues. Both exogenous recombinant maspin and maspin expressed by tumor transfectants exhibit inhibitory effects on cell motility and cell invasion as shown in modified Boyden chamber assays. In addition, three prostatic cancer cell lines treated with recombinant maspin exhibited similar inhibition of both invasion and motility, suggesting a similar mode of maspin action in these two glandular epithelial cancers. When mammary carcinoma cells were treated with recombinant maspin, the protein was shown by immunostaining to bind specifically to the cell surface, suggesting that maspin activity is membrane associated. When pretreated with antimaspin antibody, maspin loses its inhibitory effects on both invasion and motility. However, when maspin is added to these cells preceding antibody treatment, the activity of maspin is no longer inhibited by subsequent addition of the antibody. It is concluded therefore that the inhibition of invasion and motility by maspin is initially localized to the cell surface.

Antineoplastic Agents↗
PubMed1996

Arrest of in vitro T cell differentiation of normal bone marrow-derived CD34+ stem cells with thymic epithelial fragments from children with AIDS.

A novel approach is presented to assess the ability of thymic tissues obtained from children with end stage AIDS to attract normal bone marrow (BM)-derived CD34+ (lineage negative) stem cells (SCs) and support lymphopoiesis in vitro. Chemokinesis of BM-derived CD34+ SCs was analyzed by time-lapse videomicroscopy to ascertain whether an alteration in SC motility could contribute to abnormal thymopoiesis under conditions of HIV infection. The migration of SCs derived from an HIV+ donor into thymic tissue was not significantly altered compared to normal controls, as were normal SCs migrating toward thymic epithelial cell monolayers derived from an HIV+ patient. Thymic tissue obtained from children with AIDS contained nests of CD34+ SCs identified by immunofluorescence, indicating SC homing to the thymus is apparently supported in HIV infection. The ability of HIV-affected thymic epithelial fragments to support lymphopoiesis was determined by examining the initial thymocyte populations present, compared to thymocytes produced de novo in T cell-depleted thymic fragments, following a single pulse of lineage negative CD34+ CD38- SCs. In comparison to normal controls, thymocytes derived from the HIV-affected thymic epithelial fragment coculture had an increased percentage of triple negative thymocytes (28% of lymphocytes from HIV-affected tissue versus 1.5% in controls, p < 0.01) and a decreased percentage of double and single positive CD4+ thymocytes. However, CD3+CD8+ TCR alpha beta + expression was comparable to control cultured thymic epithelial fragments indicating that HIV-affected thymic epithelia were capable of supporting the development of the CD8+ lineage. In an effort to extend the information obtained to date from the histological examination of HIV-affected thymic tissue, select patient thymic tissues were maintained in culture to evaluate the capacity of undifferentiated thymic epithelial cell guirlandes to differentiate in vitro. A partial regeneration of certain subpopulations of the thymic epithelium defined by TE-4 monoclonal antibody (mAb) and CDR2 mAbs occurred during the in vitro culture. The epithelial and mesenchymal components of thymic tissues were distinguished by immunostaining for keratins (indicative of epithelium) and vimentin (a mesenchymal marker). Further evaluation of the modulation of HIV thymus, with respect to the testing of new therapeutic strategies on SCs, will be possible with this in vitro model.

ADP-ribosyl Cyclase↗
PubMed1996

Maspin: a tumor suppressing serpin.

Maspin, a serpin found in mammary epithelial cells, has been shown to have tumor suppressor activity. The gene is expressed in normal human mammary epithelial cells but down-regulated in invasive breast carcinomas. Similar patterns of expression at the RNA and protein levels are seen by Northern analysis with cells grown in culture and by immunostaining of tissues. Biological assays of invasion by tumor cells through matrigel membranes and of motility have shown that recombinant maspin inhibits both processes, and that its inhibitory action is totally lost by a single cleavage at the reaction center. Tumor transfectants expressing maspin are inhibited in growth and invasion in nude mice. Maspin is located in the cell membrane and extracellular matrix, and does not behave as a classical inhibitory serpin against any known target protease. Its mode of action is presently unknown.

Amino Acid Sequence↗
PubMed1996

Role of intermediate filaments in migration, invasion and metastasis.

The expression of intermediate filament proteins is remarkably tissue-specific which suggests that the intermediate filament (IF) type(s) present in cells is somehow related to their biological function. However, in some cancers-particularly malignant melanoma and breast carcinoma, there is a strong indication that vimentin and keratin IFs are coexpressed, thus presenting as a dedifferentiated or interconverted (between epithelial and mesenchymal) phenotype. In this review, two in vitro models are presented which recapitulate the interconverted phenotype in human melanoma and breast carcinoma, and allow, for the first time, unique observations to be made with respect to the role of IFs in cancer progression. These studies have provided direct evidence linking overexpression of keratin IFs in human melanoma with increased migratory and invasive activity in vitro, which can be down-regulated by substituting dominant-negative keratin mutants. Overexpression of vimentin IFs in the breast carcinoma model leads to augmentation of motility and invasiveness in vitro, which can be transiently down-regulated by treatment with antisense oligonucleotides to vimentin. Additional experimental evidence suggests that the mechanism(s) responsible for the differential expression of metastatic properties associated with the interconverted phenotype rest(s) in the unique interaction, either direct or indirect, of IFs with specific integrins interacting with the extracellular matrix. In this review, we discuss the observations derived from the human melanoma and breast carcinoma models to address the hypothesis that the ability to coexpress vimentin and keratins confers a selective advantage to tumor cells in their interpretation of and response to signaling cues from the extracellular matrix. The ramifications of these observations are discussed with respect to the patholophysiology of the respective in situ tumors.

Animals↗
PubMed1996

Acidic pH enhances the invasive behavior of human melanoma cells.

As a consequence of poor perfusion and elevated acid production, the extracellular pH (pHex) of tumors is generally acidic. Despite this, most in vitro experiments are still performed at the relatively alkaline pHex of 7.4. This is significant, because slight changes in pHex can have profound effects on cell phenotype. In this study we examined the effects of mildly acidic conditions on the in vitro invasive potential of two human melanoma cell lines; the highly invasive C8161, and poorly invasive A375P. We observed that culturing of either cell line at acidic pH (6.8) caused dramatic increases in both migration and invasion, as measured with the Membrane Invasion Culture System (MICS). This was not due to a direct effect of pH on the invasive machinery, since cells cultured at normal pH (7.4) and tested at acidic pH did not exhibit increased invasive potential. Similarly, cells cultured at acidic pH were more aggressive than control cells when tested at the same medium pH. These data indicate that culturing of cells at mildly acidic pH induces them to become more invasive. Since acid pH will affect the intracellular pH (pHin) and intracellular calcium ([Ca2+]in), we examined the effect of these parameters on invasion. While changes in [Ca2+]in were not consistent with invasive potential, the changes in pHin were. While these conditions decrease the overall amount of gelatinases A and B secreted by these cells, there is a consistent and significant increase in the proportion of the activated form of gelatinase B.

Calcium↗
PubMed1996

The phorbol ester TPA regulates collagen gene expression at the transcriptional level.

Previously, we reported that growth activation of quiescent 3T3-L1 cells by TPA led to a rapid increase of pro-alpha 2 (I) collagen mRNA and protein, while induction of pro-alpha 2 (I) was not observed in VT-1 cells, a line non-mitogenic in the presence of TPA (26). Here, we further examine the expression of pro-alpha 2 (I) collagen during mitogenic stimulation at the molecular level. In addition to pro-alpha 2 (I) mRNA, TPA treatment increased mRNA production of other collagen family members, pro-alpha 1 (I) and pro-alpha 1 (III) although in reduced amounts relative to pro-alpha 2 (I). In contrast to pro-alpha 2 (I), the mRNA expression profiles of several protooncogenes were regulated in both VT-1 and 3T3-L1 cells. Consistent with increased mRNA levels, TPA treated 3T3-L1 cells produced a matrix abundant in collagen type I protein. In vitro nuclear "run-on" transcription assays demonstrated a 4-fold increase in pro-alpha 2 (I) mRNA that was maximal within 10 min of TPA treatment. Using a chloramphenicol-acetyl transferase (CAT) assay, we identified a TPA sensitive domain within the promoter of the COL1A2 gene. These results establish COL1A2 as an early growth responsive gene, and that its regulation is PKC dependent. Additionally, the increased expression of protooncogenes and transin during TPA stimulation of non-mitogenic VT-1 cells indicated that the regulation of these genes is independent of PKC, indicating the existence of multiple regulatory mechanisms amongst early response genes.

3T3 Cells↗
PubMed1996

Experimental coexpression of vimentin and keratin intermediate filaments in human melanoma cells augments motility.

Intermediate filaments have been used as cell-type-specific markers in differentiation and pathology; however, recent reports have demonstrated the coexpression of vimentin (a mesenchymal marker) and keratins (epithelial markers) in numerous neoplasms, including melanoma, which has been linked to metastatic disease. To test the hypothesis that coexpression of vimentin and keratins by melanoma cells contributes to a more migratory and invasive phenotype, we co-transfected a vimentin-positive human melanoma cell line, A375P (of low invasive ability), with cDNAs for keratins 8 and 18. The resultant stable transfectants expressed vimentin- and keratin-positive intermediate filaments showed a two- to threefold increase in their invasion of basement membrane matrix and migration through gelatin in vitro. These findings were further corroborated by video cinematography. During attachment and spreading on fibronectin, the transfectants containing vimentin and keratins 8 and 18 demonstrated an increase in focal adhesions that stained positive for beta 1 integrin and phosphotyrosine, along with enhanced membrane ruffling and actin stress fiber formation. From these data, we postulate that coexpression of vimentin and keratins results in increased cytoskeletal interactions at focal contacts within extracellular matrices involving integrin cell signaling events, which contributes to a more migratory behavior.

Cell Adhesion↗
PubMed1994

v-jun oncogene suppresses both phorbol ester-induced cell invasion and stromelysin gene expression in a mouse papilloma cell line.

The viral jun (v-jun) oncogene encodes a transcription factor that can participate in the transactivation of genes through the AP-1 complex. Evidence indicates that the ability of v-jun to transform cells and stimulate transcription depends on the cell type. We have asked whether expression of the v-jun gene in benign tumor forming mouse keratinocytes that already express an activated c-rasHa oncogene would cause malignant progression. Our results showed that the v-jun transfection did not result in malignant progression; instead, we made the unexpected observation that the ability of these cells to invade reconstituted basement membrane matrix (in vitro) in response to the phorbol ester, 12-O-tetradecanoylphorbol-13-acetate, was suppressed. This phenomenon could, in part, be explained by the suppression of the induction by phorbol ester of expression of the metalloproteinase, stromelysin (transin). Of interest was the finding that 12-O-tetradecanoylphorbol-13-acetate induction of other cellular genes known to be regulated by AP-1 was not inhibited in the benign tumor cells expressing v-jun.

Animals↗
PubMed1994

Maspin, a serpin with tumor-suppressing activity in human mammary epithelial cells.

A gene encoding a protein related to the serpin family of protease inhibitors was identified as a candidate tumor suppressor gene that may play a role in human breast cancer. The gene product, called maspin, is expressed in normal mammary epithelial cells but not in most mammary carcinoma cell lines. Transfection of MDA-MB-435 mammary carcinoma cells with the maspin gene did not alter the cells' growth properties in vitro, but reduced the cells' ability to induce tumors and metastasize in nude mice and to invade through a basement membrane matrix in vitro. Analysis of human breast cancer specimens revealed that loss of maspin expression occurred most frequently in advanced cancers. These results support the hypothesis that maspin functions as a tumor suppressor.

Amino Acid Sequence↗