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Biomedical subjects

F Marks

Publications and source records attributed to F Marks.

At least 91 records · Page 5Linked to original sources
PubMed1993

Fetal upper respiratory tract function in cases of antenatally diagnosed congenital diaphragmatic hernia: preliminary observations.

Fetal upper respiratory tract function was studied in five cases of antenatally diagnosed congenital diaphragmatic hernia and in 16 cases of uncomplicated pregnancy at gestational ages ranging from 27 to 38 weeks. The evaluation of fetal upper respiratory tract function was performed using ultrasonography combined with color-flow and spectral Doppler analysis. In all cases with uncomplicated pregnancy, fetal breathing-related nasal and oropharyngeal fluid flow was seen at the level of the nose. The five cases with congenital diaphragmatic hernia all demonstrated fetal breathing activity by thoracic wall movement. In four of the fetuses, perinasal fluid flow was seen by the Doppler technique. The fetus with no demonstrated perinasal flow during breathing movements died in the early neonatal period and had pulmonary hypoplasia. Observation of the fetal breathing-related nasal and oropharyngeal fluid flow in cases of antenatally diagnosed congenital diaphragmatic hernia provides a rationale to hypothesize that the absence of this phenomenon is a useful marker for prenatal prediction of pulmonary hypoplasia.

Journal Article↗
PubMed1993

The 17 beta-oestradiol dehydrogenase of pig endometrial cells is localized in specialized vesicles.

Two monoclonal antibodies against the 17 beta-oestradiol dehydrogenase of pig endometrial cells have been used in localization studies with immunogold electron microscopy. The antibodies attach both to a fraction of dehydrogenase-rich cytoplasmic vesicles isolated from homogenates and to vesicles of similar appearance in cells. The vesicles are filled with electron-dense material. Their tagging intensity indicates a high degree of specialization. Endometrial cells from mature animals contain a host of dehydrogenase vesicles, and cells from prepubertal animals only a few. Functional aspects of the novel organelle are discussed.

Animals↗
PubMed1993

Phorbol ester TPA- and bradykinin-induced arachidonic acid release from keratinocytes is catalyzed by a cytosolic phospholipase A2 (cPLA2).

In a previous paper, we have shown that bradykinin (Bk) and the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) stimulate arachidonic acid release from HEL-30 keratinocytes along a Bk-B2 receptor G-protein-coupled pathway or a protein kinase C-dependent mechanism, respectively. Here we show a cytosolic PLA2 (cPLA2) to be responsible for this effect. This enzyme exhibited a marked acyl-group specificity towards arachidonic acid. It was activated by Ca++ in micromolar concentrations and partially translocated from the cytoplasmic to the membrane fraction upon Ca++ treatment. Translocation was also observed upon treatment of cells with either Bk or TPA. However, only with Bk was a corresponding increase of the cytoplasmic Ca++ level observed, whereas TPA-induced translocation occurred at basal Ca++ concentrations. Indirect evidence for a G protein to be involved in Bk- but not TPA-dependent cPLA2 activation was provided using non-hydrolyzable GTP derivatives. It is concluded that keratinocyte cPLA2 plays a critical role in the initiation by exogenous and endogenous factors of the eicosanoid cascade in skin.

Animals↗
PubMed1993

Proliferative responses of the skin to external stimuli.

The skin, in particular the epidermis, offers unique opportunities to investigate the induction and control of cellular proliferation and tissue homeostasis both under in vivo and in vitro conditions. Moreover, it represents one of the most feasible model systems for experimental cancer research. As the primary border of the body, the skin has important protective and defensive functions. A general response to external injury consists of a thickening of the epithelial layer (epidermal hyperplasia) combined with an inflammatory reaction. This hyperplastic transformation of the skin is a critical condition of skin tumor development (i.e., conversion and promotion) and of the wound response. It is believed to be due to a transformation of keratinocytes into an activated state characterized by an increased rate of proliferation and the ability to release a series of growth factors and other cytokines that coordinate the defense reaction (e.g., hyperproliferation, recruitment of leukocytes, activation of the immune system) along auto- and paracrine feedback loops. The initial and probably later phases of this response depend critically on a local release of eicosanoids such as prostaglandins and lipoxygenase-generated factors. A unique reaction seen upon phorbol ester treatment of mouse skin is a strong induction of the enzyme 8-lipoxygenase, which might be involved in skin tumor development by catalyzing the generation of clastogenic metabolites thought to play a role in the conversion stage. Hyperplasia may be considered to be the result of an imbalance between the rates of cell gain and cell loss.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Vibroacoustic stimulation evokes human fetal micturition.

OBJECTIVE: To examine the effect of vibroacoustic stimulation on fetal voiding as a measure of stress. METHODS: Fetal bladder volumes were examined serially by ultrasound 5 and 1 minutes before and 1 and 5 minutes after vibroacoustic stimulation (21 cases) or sham stimulation (20 cases). RESULTS: In the stimulated group, the mean (+/- SD) bladder volume decreased from 21.7 +/- 11.3 mL 1 minute before stimulation to 12.8 +/- 9.4 mL 1 minute after vibroacoustic stimulation, a statistically significant difference (P < .001). There was no significant decrease in bladder volume in the sham-stimulated fetuses. The correlations between bladder volume 1 minute before and 1 and 5 minutes after vibroacoustic stimulation were statistically significant (P < .01 and P < .001, respectively). CONCLUSION: Vibroacoustic stimulation induces fetal voiding, which may reflect a response to stress.

Acoustic Stimulation↗
PubMed1993

Residency training in contraception, sterilization, and abortion.

Obstetrics and gynecology residency program directors and chief residents were surveyed, and 80% responded to a questionnaire regarding training in contraception, sterilization, and abortion. Most program directors reported that teaching and clinical experience is provided in these areas. The chief residents, however, reported having less clinical experience than was estimated by their program directors. Most residents reported experience prescribing oral contraceptives and performing tubal ligations, but had little experience with other methods. Thirty-eight percent of graduating chief residents reported never having inserted an intrauterine device, 47% had never performed a first-trimester abortion, and 43% had never performed a dilation and evacuation. Residency programs need to set competency goals in these areas so that new practitioners will be well prepared to care for American women who wish to control their fertility.

Abortion, Induced↗
PubMed1992

Purification and properties of oestradiol 17 beta-dehydrogenase extracted from cytoplasmic vesicles of porcine endometrial cells.

Porcine endometrial oestradiol-17 beta dehydrogenase was solubilized from the particulate fraction of homogenates sedimenting between 1200 g and 10,000 g by treatment with 0.4% Brij 35 in neutral buffers. The extracts were processed by successive passage through DEAE-Sepharose, Amberlyte XAD-2 and Blue-Sepharose, and the enzyme was collected from the washed affinity matrix at 0.8 M of a 0-2 M-KCl gradient. A genuine oestrone reductase was eluted at 1.9 M-KCl. The dehydrogenase pool was resolved by butyl-Sepharose chromatography into a major (80%) peak (EDHM) eluted at 0.8 M-(NH4)2SO4 and a very hydrophobic fraction (VHF) recovered at 0.1 M. EDHM was further purified by filtration through Sephadex G-200 and cation-exchange chromatography on Mono S. Sephacryl 300 was used for VHF followed by Mono S. Enrichments from the homogenate amounted to 1074-fold for EDHM and 632-fold for VHF. A single silver-stained band at 32 kDa is seen on SDS/PAGE of EDHM, and VHF contains additional bands at 45 and 80 kDa. Polyclonal antibodies (G436) raised against EDHM and the monoclonal antibody F1 raised against VHF recognize the single 32 kDa band in EDHM and both the 32 kDa and 80 kDa bands in composite VHF. The 45 kDa band of VHF reacts with neither. Monoclonal antibody W1 raised against EDHM only recognizes the 32 kDa peptide of EDHM and VHF. The specific activity for oestradiol oxidation amounts to 4081 mu-units/mg for EDHM and to 2402 mu-units/mg for VHF. Both possess a minimal (1/260) endogenous reductase activity and are devoid of 3 beta, 3 alpha- and 20 alpha-dehydrogenases. We consider EDHM to be authentic oestradiol-17 beta dehydrogenase of porcine endometrium. The composite VHF could reflect the situation of the enzyme in vivo or result from aggregations occurring during processing.

Animals↗
PubMed1992

Differential inhibition by staurosporine of phorbol ester, bryostatin and okadaic acid effects on mouse skin.

The tumor promoters 12-O-tetradecanoyl-phorbol-13-acetate (TPA), a strong activator of protein kinase C (PKC) and okadaic acid, which is ineffective in this respect, induce a rapidly developing ('early') edema of the mouse ear. Bryostatin, another potent activator of PKC, is unable to induce an 'early' edema but causes a more delayed development of edema at a time when most of the PKC is down-regulated. The PKC inhibitor staurosporine neither inhibits the early TPA- nor the late bryostatin-induced edema, but suppresses the okadaic acid-induced edema very effectively. TPA as well as bryostatin, but not okadaic acid cause a down-regulation of PKC, which is not inhibited by staurosporine. The calmodulin antagonist cyclosporine A, which does not suppress PKC activity, very effectively inhibits the TPA-induced edema and down regulation of PKC. Hence we conclude that protein phosphorylation catalyzed by staurosporine-suppressable PKC is not involved in the induction of edema and PKC down-regulation by TPA but that a calmodulin dependent process may play a critical role in these and other TPA effects in mouse skin.

Alkaloids↗
PubMed1992

Protein kinase C zeta and eta in murine epidermis. TPA induces down-regulation of PKC eta but not PKC zeta.

Murine epidermis contains PKC zeta and eta as evidenced by the application of specific antisera. PKC zeta predominates in the cytosol and PKC eta in the particulate fraction. PKC zeta is shown to be present also in other murine tissues, with large amounts found in lung. Whereas epidermal PKC eta is completely down-regulated by treatment of mouse skin with TPA or bryostatin 1 for 18 h, PKC zeta is neither translocated by treatment with TPA for 20 min, nor down-regulated by treatment with TPA or bryostatin 1 for 18 h. PKC zeta is activated by phosphatidyl serine alone and does neither respond to Ca2+ nor to TPA. It is inhibited by staurosporine with an IC50 of 16 nM, which is within the same range of other PKC isoenzymes. The sensitivity of PKC zeta towards the staurosporine derivative K252a is similar to that of PKC alpha,beta,gamma but much higher than that of PKC delta and epsilon.

Alkaloids↗
PubMed1992

Phorbol ester-induced down-regulation of the 80-kDa myristoylated alanine-rich C-kinase substrate-related protein in Swiss 3T3 fibroblasts. Inhibition by staurosporine.

A polyclonal antiserum raised against an oligopeptide with an amino acid sequence corresponding to a sequence of the myristoylated alanine-rich C-kinase substrate (MARCKS) from mouse macrophages and rat brain recognizes the 80-kDa C-kinase substrate from Swiss 3T3 fibroblasts. Using this antiserum for quantitative determination of the 80-kDa MARCKS-related protein, we found that the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) induces a rapid down-regulation of this protein in the fibroblasts. In accordance with earlier reports, TPA causes phosphorylation of the 80-kDa protein which can be inhibited by staurosporine. Staurosporine also suppresses the TPA-induced down-regulation, possibly indicating that the down-regulation of the MARCKS-related protein is dependent on its phosphorylation by protein kinase C.

3T3 Cells↗
PubMed1991

Activation of a keratinocyte phospholipase A2 by bradykinin and 4 beta-phorbol 12-myristate 13-acetate. Evidence for a receptor-GTP-binding protein versus a protein-kinase-C mediated mechanism.

The release of arachidonic acid from cellular phospholipids and its subsequent conversion to eicosanoids is the common early response of skin keratinocytes to a wide variety of exogenous or endogenous agonists including irritant skin mitogens such as the phorbol ester, 4 beta-phorbol 12-myristate 13-acetate (PMA) or the inflammatory peptide bradykinin. In mouse keratinocytes labeled with [14C]arachidonic acid, both PMA and bradykinin induced the release of the fatty acid in a dose-dependent and time-dependent manner. Three lines of evidence indicate phospholipase A2 activity to be involved in arachidonic acid release: (a) its inhibition by mepacrine, (b) the concomitant generation of lysophosphatidylcholine from [3H]choline-labeled cells and (c) an increase in arachidonic acid release from 14C-labeled phosphatidylcholine in particulate fractions from PMA-treated and bradykinin-treated keratinocytes. Inhibition or down regulation of protein kinase C (PKC) led to a suppression of PMA-induced but not bradykinin-induced arachidonic acid release, indicating a critical involvement of this kinase in phorbol-ester-induced activation of epidermal phospholipase A2 activity. Bradykinin-induced activation of phospholipase A2 was however, shown to be mediated by specific B2 receptors coupled to GTP-binding proteins (G protein). In support of this mechanism it was demonstrated that the bradykinin-induced phospholipase A2 activity was increased in the presence of non-hydrolysable GTP but decreased upon addition of non-hydrolysable GDP analogues. Moreover, cholera toxin stimulated both basal and bradykinin-induced phospholipase A2 activity in a cAMP-independent manner, whereas pertussis toxin was found to be inactive in this respect. The data suggest that epidermal phospholipase A2 activity can be stimulated by bradykinin via a B2 receptor-G-protein-dependent pathway, which is independent of PKC and a PKC-dependent pathway which is activated by phorbol esters such as PMA.

Animals↗
PubMed1991

Immunological demonstration of epsilon PKC. Murine tissue distribution, ontogeny, cellular localization and translocation.

An antiserum raised against an epsilon PKC-specific peptide recognizes epsilon PKC with an apparent molecular weight of 97 kDa in cytosol of mouse brain. No cross-reaction with alpha, beta, gamma PKC or the delta PKC-like p76-kinase is observed. Epsilon PKC is mainly present in brain. Just traces of this PKC isoenzyme can be detected in some other murine tissues. Ontogenetic studies indicate that the amount of epsilon PKC in murine brain increases constantly and reaches a maximal level at day 7 after birth. Upon TPA activation epsilon PKC is translocated from the cytosol to the particulate fraction in a brain homogenate.

Age Factors↗
PubMed1991

Characterization of an 8-lipoxygenase activity induced by the phorbol ester tumor promoter 12-O-tetradecanoylphorbol-13-acetate in mouse skin in vivo.

An enzymatic activity has been found in cytosolic preparations from mouse epidermis which catalyzes the formation of 8-hydroperoxyeicosatetraenoic acid/8-hydroxyeicosatetraenoic acid (8-HPETE/8-HETE) from arachidonate. In contrast to 12-lipoxygenase this enzyme activity was not detectable in normal (untreated) mouse skin but only after in vivo treatment with the phorbol ester tumor promoter TPA (12-O-tetradecanoylphorbol-13-acetate). The induction showed a maximum at 24 h after TPA treatment strictly depended on the age of the mice and the TPA dose and was prevented by cycloheximide. The primary product formed from arachidonic acid was 8-HPETE, and the enzyme seems not to possess a significant peroxidase activity. This result as well as studies with specific inhibitors and its cytosolic localization indicates this enzyme to be a member of the lipoxygenase family. Most of the 8-lipoxygenase activity is located in cells of the suprabasal compartment of the epidermis. In spite of being a cytosolic enzyme 8-lipoxygenase appeared to be lipophilic to some extent and was activated by lecithin. The enzyme did not require calcium ions or ATP and showed a pH optimum at 7.5-8.0. 8-HPETE/8-HETE levels in mouse epidermis in vivo were determined by gas chromatography-mass spectrometry and found to be strongly increased after phorbol ester treatment, in agreement with the induction of 8-lipoxygenase observed.

Aging↗
PubMed1991

Immunological demonstration of a calcium-unresponsive protein kinase C of the delta-type in different species and murine tissues. Predominance in epidermis.

An antiserum raised against a delta-protein kinase C (delta-PKC)-specific peptide recognized the purified calcium-unresponsive 76-kDa protein kinase of porcine spleen in the native and the denatured form. This antiserum was used to demonstrate the delta-PKC-like enzyme in spleen of different species, in various cell types and in murine tissues by immunoblotting of the respective extracts. Due to species differences, delta-PKC-like kinases with slightly different molecular weights were observed. The enzyme was found to be present in primary murine keratinocytes, primary bovine endothelial cells, and many cell lines originating from human, rat, and murine tissues. It was present also in all murine tissues tested, predominantly in epidermis, uterus, placenta, lung, brain, spleen, and kidney. In contrast to the conventional alpha, beta, gamma-PKC, it was located almost exclusively in the particulate fraction. The delta-like PKC could be demonstrated in the epidermis and brain of newborn mice, and in both tissues its concentration increased dramatically between day 7 and 14 after birth. The delta-PKC-like kinase of mouse epidermis (p82-kinase) was down-regulated after topical application of 12-O-tetradecanoylphorbol-13-acetate (TPA) to mouse skin. The amount of the enzyme decreased to less than 20% of the controls within 16 h and recovered almost completely within 72 h after TPA. The existence of the delta-PKC-like kinase in mouse skin, papillomas, and carcinomas could also be demonstrated by immunocytochemical staining of the respective sections. The enzyme was observed predominantly in epithelial layers. A remarkable immunostaining of nuclei in skin sections disappeared after TPA treatment of the animals.

Amino Acid Sequence↗
PubMed1991

Down-regulation of protein kinase C in Swiss 3T3 fibroblasts is independent of its phosphorylating activity.

The phorbol ester TPA induces down-regulation of protein kinase C (PKC) in Swiss-3T3 fibroblasts, as determined by the use of an alpha, beta, gamma PKC-specific antiserum. PKC is almost completely degraded 10 hours after TPA treatment of the cells and recovers within 72 hours. The staurosporine derivative K252a, known to inhibit PKC activity, causes strong suppression of TPA-induced (PKC-catalyzed) protein phosphorylation in Swiss-3T3 cells. Inhibition of protein phosphorylation by K252a is still effective when the process of down-regulation is completed. However, K252a does not influence TPA-induced down-regulation of PKC at all. Thus, down-regulation of PKC is not dependent on the enzyme's phosphorylating activity and, therefore, most likely not on its autophosphorylation as has been suggested by Ohno et al. [J. Biol. Chem. 265, 6296-6300 (1990)].

Animals↗