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Biomedical subjects

M D Johnson

Publications and source records attributed to M D Johnson.

At least 217 records · Page 12Linked to original sources
PubMed1989

Oestrogenic activity of tamoxifen and its metabolites on gene regulation and cell proliferation in MCF-7 breast cancer cells.

The effects of tamoxifen, three of its in vivo metabolites and 3-hydroxytamoxifen on cellular proliferation and the induction of four oestrogen-regulated RNAs (pNR-1, pNR-2, pNR-25 and cathepsin D) have been measured in MCF-7 breast cancer cells in phenol red-free culture medium. Tamoxifen and 3-hydroxytamoxifen acted as partial oestrogens to stimulate cell growth and the levels of the pNR-2 and pNR-25 RNAs. They were full oestrogens for the induction of cathepsin D RNA and induced the pNR-1 RNA above the level found in oestrogen-treated cells. N-Desmethyltamoxifen and 4-hydroxytamoxifen behaved like tamoxifen except that N-desmethyltamoxifen did not induce the pNR-2 RNA and was only a partial oestrogen for the induction of cathepsin D RNA, and 4-hydroxytamoxifen did not induce the pNR-2 or pNR-25 RNAs. In the presence of oestradiol, the four anti-oestrogens prevented the stimulation of growth and reduced (pNR-2 and pNR-25) or increased (pNR-1) the RNA levels to those present in MCF-7 cells treated with the anti-oestrogen alone. In contrast, for cathepsin D RNA levels there was a synergistic effect of the anti-oestrogens and oestradiol. The concentration at which each anti-oestrogen was effective was related to its affinity for the oestrogen receptor. Metabolite E was a full oestrogen for the induction of cell proliferation and the oestrogen-regulated RNAs. pNR-25 and pNR-2 RNA levels correlated most closely with effects on cell proliferation. These RNAs are therefore potentially the most useful for predicting the response of breast cancer patients to tamoxifen therapy.

Breast Neoplasms↗
PubMed1989

Lipocortin-1 immunoreactivity in the normal human central nervous system and lesions with astrocytosis.

The authors have examined the cellular distribution of lipocortin-1 (L-1) in the normal and diseased central nervous system (CNS) using the peroxidase-antiperoxidase (PAP) technique with a polyclonal antibody specific for L-1. L-1 immunoreactivity was evaluated in the frontal cortex, parahippocampal gyrus/lateral ventricle, cerebellum, medulla, and spinal cord from 27 normal human fetuses, neonates, and adults without neurologic disease and in these same regions and representative lesions from 35 patients with diseases producing varying degrees of astrocytosis, including intraparenchymal hemorrhage; embolic, thrombotic, or traumatic infarctions; and Alzheimer's disease (AD). L-1 immunoreactivity was identified in ependymocytes, choroid plexus epithelia, and scattered subependymal astrocytes throughout the ventricular system from 15 weeks gestation through 82 years of age in both normal and diseased CNSs. L-1 immunoreactivity was also detected in reactive astrocytes and many macrophages surrounding each infarction regardless of site or pathogenesis and in scattered reactive astrocytes in people with AD or SDAT. The limited distribution of L-1 in CNS is consistent with the low amounts of L-1 found in brain and suggests that L-1 may participate in the normal function of ependymocytes and the pathophysiology of reactive astrocytosis.

Adult↗
PubMed1989

Co-culture of dissociated hippocampal and sympathetic cells from the neonatal rat.

When sympathetic neurones, obtained from superior cervical ganglia of postnatal rats, were grown in microcultures with cells of the postnatal hippocampal formation for 6-44 days, about 70% of the sympathetic neurones formed functional synapses on themselves or a neighbouring sympathetic neurone. In all forty-four cases in which hexamethonium (0.5-1 mM) was applied it strongly or completely blocked the synaptic interaction. This indicates that the synaptic interaction was cholinergic and raises the possibility that the denervated cells of the hippocampal formation induced the cholinergic function in the co-cultured sympathetic neurones.

Animals↗
PubMed1989

Cells that overproduce protein kinase C are more susceptible to transformation by an activated H-ras oncogene.

We recently developed rat fibroblast cell lines that stably overproduce high levels of the beta 1 form of protein kinase C (PKC). These cells display several disorders in growth control and form small microscopic colonies in agar. In the present study we demonstrate that one of these cell lines, R6-PKC3, is extremely susceptible to transformation by an activated human bladder cancer c-H-ras oncogene (T24). Compared with control cell line R6-C1, T24-transfected R6-PKC3 cells yielded a 10-fold increase in the formation of large colonies in agar. Cell lines established from these colonies displayed a highly transformed morphology, expressed the T24-encoded p21 ras protein, continued to express high levels of PKC, and were highly tumorigenic in nude mice. These results provide genetic evidence that PKC mediates some of the effects of the c-H-ras oncogene on cell transformation. Data are also presented suggesting that optimum synergistic effects between c-H-ras and PKC require critical levels of their respective activities. These findings may be relevant to the process of multistage carcinogenesis in tissues containing cells with an activated c-H-ras oncogene.

Animals↗
PubMed1989

Daily sequential changes in plasma atrial natriuretic factor concentrations in mechanically ventilated low-birth-weight infants. Effect of surfactant replacement.

Plasma atrial natriuretic factor (ANF) concentrations are elevated in mechanically ventilated infants. To test the hypothesis that changes in pulmonary compliance affect ANF concentration, we measured plasma ANF concentrations sequentially in low-birth-weight, ventilated infants who either received surfactant replacement or placebo on day 1. ANF concentrations were elevated as compared to adult controls on day 1 and increased significantly on days 2 and 3 before declining. Day 5 concentrations were not different from day 1. Several infants had ANF concentrations greater than 1,280 pg/ml on days 2-4. There were no significant differences in ANF concentrations between surfactant-treated and non-treated infants on any day. ANF concentrations increased in parallel with changes in salt and water balance, but no significant relationships were apparent between absolute ANF concentrations and parameters of salt and water balance. The results suggest that ANF secretion is elevated in infants with pulmonary disease. While the temporal relationship between the initial rise in ANF concentration and increase in salt and water excretion suggest that ANF is involved in this diuresis, the role it may play is unclear from the present data.

Atrial Natriuretic Factor↗
PubMed1989

Ontogeny of epidermal growth factor receptor/kinase and of lipocortin-1 in the ovine lung.

We have examined the ontogeny and distribution of the epidermal growth factor receptor/kinase (EGF receptor) and of lipocortin-1, a major cellular substrate of the EGF receptor, in a developmental series of 13 normal ovine fetal lungs (44-145 d of gestation) using the peroxidase anti-peroxidase technique with two extensively characterized polyclonal antibodies recognizing the EFG receptor and one polyclonal antibody recognizing lipocortin-1. Immunoreactive EGF receptor/kinase and lipocortin-1 were detected in conducting airway epithelium by the end of the first trimester of pregnancy before bronchial glands could be identified. This was followed at two-thirds of gestation by immunoreactivity in bronchial glands and large bronchioles adjacent to positive bronchi. By seven-eighths of gestation conducting airway epithelium no longer contained consistently detectable immunostaining for EGF receptor, although lipocortin-1 was identified until term in all levels of conducting airways. In contrast, neither EGF receptor nor lipocortin-1 immunoreactivity was detected in alveolar type I or type II epithelial cells, fibrocytes, chondrocytes, smooth muscle, or endothelial cells at any gestational age. These findings suggest that EGF receptor and lipocortin-1 may participate in early airway development.

Animals↗
PubMed1989

Osteoblastic meningioma of the fourth ventricle.

Meningiomas of the fourth ventricle are rare neoplasms. Only meningothelial and fibroblastic subtypes, purportedly arising from the tela choroidea, have been described. In this report we describe clinical, neuroradiological and pathological findings in a 52-year-old man with mild hydrocephalus produced by a large, calcified, osteoblastic meningioma of the fourth ventricle.

Cerebral Ventricles↗
PubMed1989

Mast cell and lymphoreticular infiltrates in neurofibromas. Comparison with nerve sheath tumors.

Cellular heterogeneity produced by non-Schwannian elements may distinguish neurofibromas from other Schwann cell neoplasma and contribute to a different tumor biology. The present study compared cell counts of mast cells, T and B lymphocytes, and macrophages in 32 neurofibromas with those in 27 schwannomas, 9 malignant nerve sheath tumors, and 17 traumatic neuromas. Immunohistochemical and histochemical analyses were performed on formalin-fixed, paraffin-embedded tissues using two monoclonal antibodies against B-lymphocyte epitopes (LN-1 and LN-2), one monoclonal antibody against T-lymphocyte epitopes (UCHL-1), one polyclonal antibody recognizing alpha 1-antichymotrypsin (ACT), a macrophage/histiocytemarker, and toluidine blue O stains. Neurofibromas contained relatively high concentrations of mast cells significantly greater than the concentrations in other neoplastic or reactive nerve sheath tumors. Most neurofibromas also displayed moderate concentrations of LN-2 immunoreactive cells, similar to the concentrations in traumatic neuromas and not statistically different from cell counts in other tumor types. Limited, variable LN-1 and UCHL-1 immunoreactive infiltrates were detected in neurofibromas and some peripheral schwannomas. Rare or moderate ACT immunoreactivity was detected in the majority of neurofibromas, in contrast with the absence, or rare appearance, of ACT immunostaining in cranial and peripheral nerve schwannomas and moderate numbers of immunoreactive cells in many malignant nerve sheath tumors. Mast cells are an important cellular marker of neurofibromas and may participate in the pathogenesis of these neoplasms.

Antibodies, Monoclonal↗
PubMed1989

Anabolic steroid use by male adolescents.

Anabolic steroids have recently been used by professional and college athletes to improve athletic ability by increasing muscle size and strength. A study was done to determine the extent of steroid use and knowledge about these drugs in a population of high school male adolescents in a southern state. A self-report questionnaire, which allowed multiple answers for each question, was administered to 853 male students in six high schools. Results indicated that an average of 11% had used or were using anabolic steroids. The following were assessed: the reasons for steroid use, the sources from which the students received information about steroids, their familiarity with the physiologic effects and complications of steroid use, and the extent of their involvement in sports. The results suggest that a segment of male adolescents are using anabolic steroids without fully understanding the risks of such behavior. Health care providers need to become knowledgeable about steroids so that they may better educate adolescents about the potential deleterious effects of these agents.

Adolescent↗
PubMed1989

Disturbances in growth control and gene expression in a C3H/10T1/2 cell line that stably overproduces protein kinase C.

We have utilized a retroviral expression vector to construct a series of C3H/10T1/2 murine fibroblast cell lines that stably overexpress a full length cDNA encoding rat protein kinase C beta 1 (PKC). These cell lines contain 3-11 fold greater PKC enzyme activity than parental cells or control cells that carry an integrated vector lacking the cDNA insert. 10T1/2-PKC-4, a line with an 11-fold increase in PKC activity, is morphologically altered, grows to 4-fold higher saturation density, and has decreased adhesiveness when compared to control cells. These cells also show constitutive and inducible alterations in the levels of two PKC-regulated genes, phorbin and TPA-R1. However, 10T1/2-PKC-4 cells do not have a transformed morphology, are incapable of growth in soft agar, and are non-tumorigenic in nude mice. When 10T1/2-PKC-4 cells are cultured in 2.5% calf serum and 100 ng ml-1 TPA, numerous large, dense foci appear 2-3 weeks after the cells reach confluence. TPA is required for focus formation, and control cells do not form foci under the same conditions. However, when such foci are isolated and grown in the absence of TPA, the cells closely resemble later passage 10T1/2-PKC-4 cells. Therefore, the events leading to focus formation appear to be reversible. The 10T1/2-PKC-4 cell line should be valuable for more precisely defining molecular events relevant to tumor promotion and multistage carcinogenesis.

Animals↗
PubMed1988

Overproduction of protein kinase C causes disordered growth control in rat fibroblasts.

We have generated a series of rat fibroblast cell lines that stably overexpress a full-length cDNA encoding the beta 1 form of protein kinase C (PKC). These cell lines contain a 20- to 53-fold increase in PKC activity and exhibit dramatically enhanced morphologic changes following exposure to the tumor promoter 12-O-tetradecanoyl phorbol-13-acetate (TPA). They grow to a high saturation density in monolayer cultures and, when maintained at postconfluence, develop small, dense foci. In contrast to control cells, which display complete anchorage dependence, PKC-overproducing cells form small colonies in soft agar in the absence of TPA and large colonies in the presence of TPA. Thus, the mere overproduction of a single form of PKC is sufficient to confer multiple growth abnormalities in rat fibroblasts. These results provide direct evidence that PKC plays a critical role in growth control and that it mediates several of the cellular effects of the phorbol ester tumor promoters. They also suggest that the activation of PKC may be of central importance in the process of multistage carcinogenesis.

Amino Acid Sequence↗
PubMed1988

Structural and functional studies of protein kinase C.

It has now become clear that protein kinase C (PKC) plays a fundamental role in cellular growth control in higher eukaryotes. In addition, since PKC has also been shown to be the high-affinity intracellular receptor for several classes of tumor promoters, the study of PKC has also become a central focus of current work in cancer research. We have isolated cDNA clones encoding several forms of this enzyme, and we have used these clones to begin to study in detail the role of PKC in growth control and tumor promotion. The complete primary structure of one of these forms, designated PKC beta 1, exhibits structural and functional characteristics which are shared among all of the currently identified forms of PKC. These include an amino terminal cysteine-rich domain which mediates Ca2+ and phospholipid binding, tumor promoter binding, and membrane association, and a carboxy terminal catalytic domain which possesses serine/threonine protein kinase activity. To further characterize the function of PKC, we have generated a series of rat fibroblast cell lines which stably overexpress a full-length cDNA encoding the beta 1 form of this enzyme. These cell lines contain a 20- to 53-fold increase in PKC activity, and also have an increase in high affinity phorbol ester receptors, relative to control cells. They also exhibit dramatically enhanced morphologic changes in response to treatment with the tumor promoter 12-0-tetradecanoyl phorbol-13-acetate (TPA). These cell lines grow to a higher saturation density in monolayer culture and, when maintained at post-confluence, develop small, dense foci. In contrast to the control cells, which display complete anchorage dependence, the cell lines that overproduce PKC form small colonies in soft agar in the absence of TPA, and larger colonies in the presence of TPA. Thus, the mere overproduction of a single form of PKC is sufficient to confer anchorage independent growth and other growth abnormalities in rat fibroblasts. Taken together, these results provide direct evidence that PKC plays a critical role in normal cellular growth control and that it mediates several, and perhaps all of the cellular effects of the phorbol ester tumor promoters.

Amino Acid Sequence↗
PubMed1988

The difficult airway in obstetric anesthesia: techniques for airway management and the role of regional anesthesia.

A case is presented illustrating the use of a continuous spinal anesthetic in a parturient with a difficult airway who required urgent cesarean delivery. Options for endotracheal intubation of a parturient with a difficult airway are reviewed. The role of regional anesthesia in this setting is discussed. The most appropriate methods for intubation of the obstetric patient are direct laryngoscopy, the lighted stylet, and fiberoptic endoscopy. Available data suggest that regional anesthesia, specifically continuous spinal anesthesia, may be a safe and effective option for management of a parturient with a difficult airway. Further investigation of this technique is merited.

Adult↗
PubMed1988

Construction and characterization of a retroviral vector demonstrating efficient expression of cloned cDNA sequences.

We describe the construction and properties of a retroviral expression vector, designated pMV-7, designed to transfer unselected cDNAs and produce their encoded proteins in recipient cells. The vector is flanked by the long terminal repeats (LTRs) of the Moloney murine sarcoma virus (MSV) and contains the selectable drug resistance gene neo under the regulation of the herpes simplex virus (HSV) thymidine kinase (tk) promoter. Unique Eco RI and Hind III sites facilitate the introduction of sequences whose transcription is regulated by the 5' LTR. We have inserted cDNAs encoding: (i) the human lymphocyte antigen T4, (ii) the human lymphocyte antigen T8, and (iii) the murine hypoxanthine-guanine phosphoribosyl transferase (HPRT), into the pMV-7 vector. These constructions were used to transduce recipient cells to the neo+ phenotype. In each case, functional assays demonstrated that 65-92% of the neo+ clones produced the appropriate protein encoded by its corresponding cDNA. These clones were characterized further by analyzing the expression of vector-regulated transcripts. The neo+T4+ clones expressed a single full-length LTR-to-LTR transcript as detected by a T4 probe. The neo+T8+ clones, however, expressed both a full-length LTR-to-LTR transcript and an additional smaller transcript as detected by a T8 probe. This smaller transcript probably resulted from the utilization of cryptic signals which control 3' RNA processing. Furthermore, all of the neo+ clones expressed a transcript that initiated from the tk promoter, contained the neo gene, and used polyadenylation signals provided by the 3' LTR. Thus, the pMV-7 vector is capable of high-efficiency transfer and high-frequency expression of the cDNA-encoded protein.

Animals↗