Biomedical subjects

R Gomez

Publications and source records attributed to R Gomez.

At least 127 records · Page 7Linked to original sources

PubMed1994

Matrix vesicles produced by osteoblast-like cells in culture become significantly enriched in proteoglycan-degrading metalloproteinases after addition of beta-glycerophosphate and ascorbic acid.

Matrix vesicles, media vesicles, and plasma membranes from three well-characterized, osteoblast-like cells (ROS 17/2.8, MG-63, and MC-3T3-E1) were evaluated for their content of enzymes capable of processing the extracellular matrix. Matrix vesicles were enriched in alkaline phosphatase specific activity over the plasma membrane and contained fully active neutral, but not acid, metalloproteinases capable of digesting proteoglycans, potential inhibitors of matrix calcification. Matrix vesicle enrichment in neutral metalloproteinase varied with the cell line, whereas collagenase, lysozyme, hyaluronidase, and tissue inhibitor of metalloproteinases (TIMP) were not found in any of the membrane fractions examined. MC-3T3-E1 cells were cultured for 32 days in the presence of ascorbic acid (100 micrograms/ml), beta-glycerophosphate (5 mM), or a combination of the two, to assess changes in matrix vesicle enzymes during calcification. Ascorbate or beta-glycerophosphate alone had no effect, but in combination produced significant increases in both active and total neutral metalloproteinase in matrix vesicles and plasma membranes, with the change seen in matrix vesicles being the most dramatic. This correlated with an increase in the formation of von Kossa-positive nodules. The results of the present study indicate that osteoblast-like cells produce matrix vesicles enriched in proteoglycan-degrading metalloproteinases. In addition, the observation that matrix vesicles contain significantly increased metalloproteinases under conditions favorable for mineralization in vitro lends support to the hypothesis that matrix vesicles play an important role in extracellular matrix processing and calcification in bone.

3T3 Cells↗

PubMed1994

Effects of experimenter and mother presence on the attentional performance and activity of hyperactive boys.

The attentional performance, activity, and off-task behavior of hyperactive boys with and without conduct problems and normal boys were compared on a cancellation task under three conditions: when performing the task alone, with mother present, and with experimenter present. Results indicated that both the hyperactive groups achieved poorer attentional scores than normal subjects in the alone and mother present conditions, but improved in the experimenter present condition. The performance of the hyperactive boys with conduct problems was particularly affected by this condition. The activity and off-task behavior scores of both the hyperactive groups were higher than controls in all conditions, although the hyperactive boys with conduct problems decreased in off-task behavior when the experimenter was present. Attention and behavior scores were not significantly correlated. The implications of these findings for assessment of hyperactivity, and the role of noncompliance in the attentional behavior of hyperactive children, are discussed.

Attention↗

PubMed1994

Ultrasonographic examination of the uterine cervix is better than cervical digital examination as a predictor of the likelihood of premature delivery in patients with preterm labor and intact membranes.

OBJECTIVE: The purpose of this study was to compare the diagnostic performance of ultrasonographic and digital examination of the cervix in the prediction of preterm delivery in patients presenting with preterm labor and intact membranes. STUDY DESIGN: Endovaginal ultrasonography was performed in 59 patients admitted with preterm labor (20 to 35 weeks) and cervical dilatation of < 3 cm. Cervical parameters evaluated included endocervical length, the presence of funneling, funnel length, funnel width, cervical index ([Funnel length + 1]/Endocervical length), and cervical dilatation and effacement as determined by digital examination. Outcome variables were the occurrence of preterm delivery (< 36 weeks) and the admission-to-delivery interval. RESULTS: The prevalence of preterm delivery was 37.3% (22/59). Receiver-operator characteristic curve and logistic regression analyses indicated a significant relationship between the occurrence of preterm delivery and ultrasonographic cervical parameters (p < 0.005 for each) but not with the results of digital examination of the cervix. Survival analysis demonstrated a shorter admission-to-delivery interval for patients with an abnormal cervical index or endocervical length (p < 0.005 for each). CONCLUSIONS: Endovaginal ultrasonographic examination of the uterine cervix is more accurate than digital examination of the cervix in the assessment of the risk for preterm delivery in patients with preterm labor and intact membranes.

Biometry↗

PubMed1994

Leukemia inhibitory factor: association with intraamniotic infection.

OBJECTIVE: Our purpose was to investigate whether leukemia inhibitory factor is associated with intraamniotic infection. STUDY DESIGN: A comparative clinical study of amniotic fluid leukemia inhibitory factor concentrations was performed. RESULTS: Leukemia inhibitory factor was undetectable (< 1 ng/ml) by radioreceptor assay during normal pregnancy at midtrimester and at term. Among women in labor those with intraamniotic infection had higher leukemia factor concentrations than those without infection before term (p < 0.001) and at term (p < 0.005). The leukemia inhibitory factor concentrations correlated with the amniotic fluid white blood cell counts (r = 0.47) (p < 0.001). In cultured human gestational tissue explants, leukemia inhibitory factor release was significantly enhanced by endotoxin, interleukin-1 alpha, and tumor necrosis factor-alpha however, leukemia inhibitory factor did not enhance the release of prostaglandin E2 by these tissues. CONCLUSIONS: Amniotic fluid leukemia inhibitory factor concentrations were elevated during intraamniotic infection and gestational tissues released leukemia inhibitory factor in response to bacterial products and inflammatory mediators.

Amnion↗

PubMed1994

Amniotic fluid prostanoid concentrations increase early during the course of spontaneous labor at term.

OBJECTIVE: The purpose of this study was to determine whether amniotic fluid concentrations of prostanoids increase during spontaneous labor at term. STUDY DESIGN: Amniotic fluid was retrieved transabdominally from 168 patients in spontaneous labor and from 82 patients not in labor. Prostaglandin E2, prostaglandin F2 alpha, 13, 14-dihydro-15-keto-prostaglandin F2 alpha, thromboxane B2, and 6-keto-prostaglandin F1 alpha concentrations were measured with sensitive and specific radioimmunoassays previously validated for amniotic fluid. Statistical analysis was conducted with Kruskal-Wallis analysis of variance, followed by Dunn's test for multiple comparisons. RESULTS: (1) Amniotic fluid concentrations of all prostanoids were significantly higher in patients in early labor (cervical dilatation of < or = 3 cm) than in patients not in labor. (2) The magnitude of the increase in amniotic fluid prostanoid concentrations during early labor was significantly greater for prostaglandin F2 alpha and 13,14-dihydro-15-keto-prostaglandin F2 alpha than for prostaglandin E2, thromboxane B2, and 6-keto-prostaglandin F1 alpha. (3) Patients in the active phase of labor with cervical dilatations between 4 and 7 cm did not have higher prostanoid concentrations than those in early labor (cervical dilatation of < or = 3 cm). (4) A significant increase in amniotic fluid concentrations of prostaglandin F2 alpha and 13,14-dihydro-15-keto-prostaglandin F2 alpha was found in patients with advanced cervical dilatation (8 to 10 cm) in comparison with those in early labor (< 3 cm). CONCLUSION: Amniotic fluid prostanoid concentrations increase early during the course of spontaneous labor at term.

Amniotic Fluid↗

PubMed1994

The value of amniotic fluid interleukin-6 determination in patients with preterm labor and intact membranes in the detection of microbial invasion of the amniotic cavity.

OBJECTIVES: Our purpose was to (1) determine the value of amniotic fluid interleukin-6 determination in the detection of microbial invasion of the amniotic cavity and (2) compare interleukin-6 to other rapid tests in the evaluation of preterm labor. STUDY DESIGN: Amniotic fluid interleukin-6 was determined quantitatively by enzyme-linked immunosorbent assay in 91 amniotic fluid specimens obtained by amniocentesis in 89 patients with preterm labor. Amniotic fluid cultures for aerobes, anaerobes, and mycoplasma species were performed. Receiver-operator characteristic curve analysis, logistic regression analysis, and Cox's proportional-hazards model were used to explore the relationship between several explanatory and outcome variables. Diagnostic index values of interleukin-6, glucose level, Gram stain, leukocyte esterase, and limulus amebocyte lysate assay for prediction of a positive amniotic fluid culture, preterm delivery, clinical infection, and neonatal sepsis were calculated. RESULTS: The prevalence of positive amniotic fluid cultures was 13% (12/89). The median interleukin-6 concentration in patients with positive cultures was 241.8 ng/ml, in contrast to 0.291 ng/ml in patients with negative cultures (p. < 0.005). Sensitivity and specificity of an interleukin-6 level > or = 6.17 ng/ml was 75% and 79%, in contrast to that of glucose, < or = 12 mg/dl (83% and 86%) for a positive amniotic fluid culture and sensitivity (p = 0.26, z test). All patients with an interleukin-6 level > 6.17 ng/ml were delivered preterm, in contrast to 85.2% of patients with a glucose level < or = 12 mg/dl. When all rapid tests and clinical parameters were considered simultaneously in the logistic model, only interleukin-6 maintained a significant relationship to preterm birth (odds ratio 35, p = 0.003). Cox's proportional analysis demonstrated a strong relationship between interleukin-6 and the amniocentesis-to-delivery interval after clinical variables were controlled for (hazard ratio 3.01, p < 0.00001). CONCLUSION: Amniotic fluid interleukin-6 determination may be a useful adjunct to our armamentarium of rapid tests to exclude infection and predict delivery in patients with preterm labor and intact membranes.

Amniocentesis↗

PubMed1994

The natural interleukin-1 receptor antagonist in the fetal, maternal, and amniotic fluid compartments: the effect of gestational age, fetal gender, and intrauterine infection.

OBJECTIVES: The interleukin-1 receptor antagonist is a newly discovered cytokine that blocks the biologic effects of interleukin-1 in vitro and in vivo. This cytokine is a physiologic component of amniotic fluid and is considered to be of critical importance in the homeostasis of the cytokine network. This study was undertaken to systematically examine the bioavailability of interleukin-1 receptor antagonist in the maternal, fetal, and amniotic fluid compartments during term and preterm parturition in women with and without microbial invasion of the amniotic cavity. STUDY DESIGN: The patient population consisted of (1) pregnant women in the midtrimester (n = 42), (2) patients who underwent cordocentesis for diagnostic purposes (n = 39), (3) patients with preterm labor (n = 126), (4) women with term gestation (n = 102), and (5) healthy nonpregnant women (n = 8). Amniotic fluid was cultured for aerobic and anaerobic bacteria, as well as Mycoplasma sp. Interleukin-1 receptor antagonist concentrations were determined by enzyme-linked immunoassay in maternal and fetal plasma, amniotic fluid, and neonatal urine. Microbial invasion of the amniotic cavity was defined as the presence of a positive amniotic fluid culture for microorganisms. RESULTS: (1) Interleukin-1 receptor antagonist was normally present in fetal plasma samples obtained by cordocentesis, and its concentration increased with advancing gestational age (n = 39; r = 0.61, p < 0.001). (2) Patients at term not in labor had higher amniotic fluid interleukin-1 receptor antagonist concentrations than patients in the midtrimester (median 40.1 ng/ml, range 5.7 to 213.1 vs median 16.2 ng/ml, range 3.2 to 62.2, respectively, p < 0.001). (3) Amniotic fluid and cord plasma interleukin-1 receptor antagonist concentrations were significantly higher in patients with preterm labor and microbial invasion of the amniotic cavity than in those without microbial invasion of the amniotic cavity (amniotic fluid: median 219.9 ng/ml, range 35.4 to 504 vs median 80.6 ng/ml, range 24.3 to 399, respectively, p < 0.001; umbilical cord plasma: median 4.8 ng/ml, range 0.3 to 167.0 vs median 1.0 ng/ml, range 0 to 276.0, respectively, p < 0.05). In contrast, these differences were not found in patients with term labor either with or without microbial invasion of the amniotic cavity. (4) In both term and preterm patients the amniotic fluid and neonatal urine concentrations of interleukin-1 receptor antagonist were significantly higher in female fetuses than in male fetuses (amniotic fluid, preterm: median 191.9 ng/ml, range 51.6 to 504.0 vs median 61.1 ng/ml, range 11.5 to 284.9, respectively, p < 0.001; amniotic fluid, term: median 58.7 ng/ml, range 25.5 to 264.0 vs median 33.9 ng/ml, range 3.4 to 132.4, respectively, p < 0.001; neonatal urine: median 317 ng/ml, range 59.0 to 440.8 vs median 12.2 ng/ml, range 2.5 to 61.6, respectively, p < 0.005). CONCLUSIONS: (1) Interleukin-1 receptor antagonist is physiologically present in the fetal, maternal, and amniotic fluid compartments; (2) microbial invasion of the amniotic cavity in the preterm gestation is associated with a significant increase in the concentrations of this cytokine in the fetal and amniotic fluid compartments but not in maternal plasma; (3) fetal urine is a source of amniotic fluid interleukin-1 receptor antagonist; (4) fetal plasma interleukin-1 receptor antagonist concentrations increase with gestational age; (5) there is a significant effect of fetal gender in amniotic fluid and neonatal urine concentrations of interleukin-1 receptor antagonist.

Amnion↗

PubMed1994

Mother-child interactions and noncompliance in hyperactive boys with and without conduct problems.

Mother-child interaction, and parent ratings of child noncompliance and defiance among hyperactive boys with conduct problems (H/CP), hyperactive boys without conduct problems (H), and normal boys (N) were compared. Results indicated more negative mother-child interactions and more noncompliance in the H/CP group than in the other two groups. The H group was more noncompliant than normal children, but these groups showed no differences in defiance, nor in the behaviour of mothers. The implications of these findings in relation to the development of conduct problems in hyperactive children, treatment and research are discussed.

Attention Deficit Disorder with Hyperactivity↗

PubMed1994

Macrophage inflammatory protein-1 alpha in term and preterm parturition: effect of microbial invasion of the amniotic cavity.

PROBLEM: This study was conducted to determine whether: (1) gestational age, parturition, and microbial invasion of the amniotic cavity (MIAC) are associated with changes in amniotic fluid concentrations of immunoreactive macrophage inflammatory protein-1 alpha; (2) amniotic fluid concentrations of macrophage inflammatory protein-1 alpha are correlated with the white blood cell count and the concentrations of interleukin-8 in amniotic fluid. METHOD: Amniotic fluid was retrieved by amniocentesis from 126 patients; 54 women with preterm labor and intact membranes (no MIAC-delivery at term, N = 21; no MIAC-preterm delivery, N = 16; MIAC-preterm delivery, N = 17); 62 patients at term (no labor, N = 19; labor-no MIAC, N = 20; labor-MIAC, N = 23); and 10 patients in the midtrimester of pregnancy. Amniotic fluid was cultured for aerobic, anaerobic and Mycoplasma species. Determinations of amniotic fluid macrophage inflammatory protein-1 alpha and interleukin-8 were performed with immunoassays validated for amniotic fluid (sensitivity: 14.2 pg/ml and 0.3 ng/ml, respectively). Kruskal-Wallis analysis of variance (ANOVA) for censored data, Mann-Whitney U test and Spearman's rank correlation were performed for analysis. RESULTS: 1) Amniotic fluid macrophage inflammatory protein-1 alpha was present in only 31.0% (9/29) of patients not in labor (midtrimester and term). 2) Patients with preterm labor and MIAC had higher amniotic fluid concentrations of macrophage inflammatory protein-1 alpha than those without MIAC (no MIAC-delivery at term: median 0.0 pg/ml, range 0.0-221.2; no MIAC-preterm delivery: median 37.4 pg/ml, range 0.0-494.6; MIAC-preterm delivery: median 7171.0 pg/ml, range 402.5-37994.0; P < 0.00001). 3) Among patients at term, MIAC was associated with higher concentrations of amniotic fluid macrophage inflammatory protein-1 alpha than patients without MIAC (no labor: median 0.0 pg/ml, range 0.0-25.6; labor-no MIAC: median 16.7 pg/ml, range 0.0-161.6; labor-MIAC: median 103.8 pg/ml, range 0.0-4349.0, P < 0.001). 4) Among patients in preterm labor, a strong correlation was found between amniotic fluid concentrations of macrophage inflammatory protein-1 alpha and interleukin-8 (r = 0.9, P < 0.00001) and between amniotic fluid macrophage inflammatory protein-1 alpha concentrations and amniotic fluid white blood cell count (r = 0.6, P < 0.0001). CONCLUSIONS: (1) Macrophage inflammatory protein-1 alpha is undetectable in most amniotic fluid samples from patients in the midtrimester of pregnancy and at term not in labor. (2) Microbial invasion of the amniotic cavity is associated with increased concentrations of immunoreactive amniotic fluid macrophage inflammatory protein-1 alpha in both term and preterm gestations. (3) Amniotic fluid macrophage inflammatory protein-1 alpha concentrations significantly correlate with interleukin-8 levels and white blood cell count in amniotic fluid. Our data strongly suggest a role for macrophage inflammatory protein-1 alpha in the mechanisms responsible for the recruitment of leukocytes into the amniotic cavity during the course of intrauterine infection.

Amnion↗

PubMed1994

The value of amniotic fluid interleukin-6, white blood cell count, and gram stain in the diagnosis of microbial invasion of the amniotic cavity in patients at term.

PROBLEM: Subclinical microbial invasion of the amniotic cavity occurs in 18.8% of women with term labor and intact membranes and in 34% of patients with term PROM and is a risk factor for the development of puerperal infection related morbidity. Although amniotic fluid white blood cell count, interleukin-6 determination, and Gram stain examination have been used for the diagnosis of intrauterine infection in patients with preterm labor and preterm premature rupture of membranes, no information is available about the accuracy and specific cut-off values for these tests in patients at term. The purpose of this study was to compare the performance of the amniotic fluid Gram stain examination, white blood cell count, and interleukin-6 determination in the identification of microbial invasion of the amniotic cavity in patients at term with and without PROM. METHOD: Amniotic fluid was retrieved from 148 patients with term gestations (90 patients with spontaneous labor and intact membranes and 58 patients with PROM). Samples were cultured for bacteria and Mycoplasma species. Amniotic fluid Gram stain, white blood cell count, and interleukin-6 determinations (ELISA, sensitivity: 43 pg/ml) were performed in all samples. Microbial invasion of the amniotic cavity was defined as a positive amniotic fluid culture for microorganisms. Analysis was conducted using Mann-Whitney U test, Fisher's exact test, receiver operating characteristic curves and logistic regression. RESULTS: Patients with spontaneous labor and intact membranes: The prevalence of microbial invasion of amniotic cavity in this group was 15.6% (14/90). The most sensitive test for the detection of microbial invasion of the amniotic cavity was amniotic fluid interleukin-6 determination (sensitivity for: interleukin-6 > or = 5.7 ng/ml = 86%, white blood cell count > or = 20 cells/mm3 = 64%, Gram stain = 28%). The most specific test was the Gram stain of the amniotic fluid (specificity for: Gram stain = 84%, interleukin-6 = 79% and white blood cell count = 63%). Multiple logistic regression demonstrated that amniotic fluid interleukin-6 concentration was the only covariate that retained statistical significance when intrauterine infection was used as outcome variable. Patients with PROM: The prevalence of a positive amniotic fluid culture in this group was 39.7% (23/58). Logistic regression demonstrated that only interleukin-6 retained a significant relationship with the results of amniotic culture when all variables were entered simultaneously into a model to predict amniotic fluid culture results. The most sensitive tests for the detection of intrauterine infection were interleukin-6 determination and white blood cell count (sensitivity for interleukin-6 > or = 3.4 ng/ml and white blood cell count > or = 20 cells/mm3 = 69.6% for both). The most specific test was Gram stain (97.1%). CONCLUSIONS: Amniotic fluid interleukin-6 determination is the best rapid test for the detection of microbial invasion of the amniotic cavity in patients at term with and without PROM. When this test is not available, amniotic fluid Gram stain and white blood cell count represent valid diagnostic tools to assess the microbial state of amniotic cavity.

Amniotic Fluid↗

PubMed1993

Projections from the nucleus tractus solitarii to the spinal cord.

Projections from the nucleus tractus solitarii (NTS) to the spinal cord were demonstrated in the male Sprague-Dawley rat. In retrograde transport studies, a horseradish peroxidase conjugate or a fluorescent dye, FluoroGold, were injected into midcervical or upper thoracic spinal segments. Most solitariospinal neurons were multipolar or bipolar and located between the obex and spinomedullary junction. Solitariospinal neurons were concentrated in proximity to the ventral border of the solitary tract and extended dorsally into the intermediate division and ventrolaterally into the intermediate reticular zone (IRt) of the lateral tegmental field. This subgroup predominantly projects to midcervical spinal segments. A subset of small neurons was retrogradely labeled from cervical or thoracic spinal segments in the medial commissural nucleus and contiguous with a periventricular group surrounding the central canal. In anterograde transport studies, iontophoretic deposits of Phaseolus vulgaris leucoagglutinin were centered stereotaxically on sites in NTS identified by retrograde transport data. The lectin was incorporated by neurons of the solitary complex and transported bilaterally by axons that emerged from the nucleus and entered the reticular formation. The solitario-reticular (transtegmental) pathway irradiated diagonally across the IRt and extended caudally into the cervical lateral funiculus and spinal gray. A small periventricular-spinal pathway also descended longitudinally to the neuraxis. Solitariospinal neurons project to superficial lamina of the dorsal horn, laminae VII and X and ventral horn. The projections are predominantly contralateral to phrenic and intercostal motor nuclei and ipsilateral to the intermediolateral cell column. The solitariospinal projection represents the shortest route in the central nervous system, other than the local intraspinal reflex, through which first order visceral afferents signal cardiorespiratory and alimentary motor nuclei.

Animals↗

PubMed1993

Identification of Ras farnesyltransferase inhibitors by microbial screening.

A microbial screen using a yeast strain with conditional deficiency in the GPA1 gene was carried out to search for inhibitors of protein farnesyltransferase (PFT). A strain of Streptomyces was found to produce active compounds named UCF1-A, UCF1-B, and UCF1-C. Structural determination of these compounds revealed that UCF1-C is identical to the known antibiotic, manumycin, whereas UCF1-A and UCF1-B are structurally related to manumycin. All three UCF1 compounds suppress the lethality of gpa1 disruption, with UCF1-C exhibiting the strongest activity. UCF1 inhibits yeast as well as rat brain PFT. Fifty percent inhibition of yeast PFT activity is observed with 5 microM UCF1-C. Kinetic analyses of the inhibition suggest that UCF1-C acts as a competitive inhibitor of PFT with respect to farnesyl pyrophosphate, exhibiting a Ki of 1.2 microM, whereas the same compound appears to act as a noncompetitive inhibitor of PFT with respect to the farnesyl acceptor, the Ras protein. UCF1-C shows significant activity to inhibit the growth of Ki-ras-transformed fibrosarcoma, raising the possibility of its use as an antitumor drug.

Alkyl and Aryl Transferases↗

PubMed1993

Purified yeast protein farnesyltransferase is structurally and functionally similar to its mammalian counterpart.

Protein farnesyltransferase (FTase) catalyses the addition of a farnesyl group to a cysteine within the so-called 'CAAX box' at the C-terminus of various proteins. In the present paper we report purification of Saccharomyces cerevisiae FTase to near-homogeneity. This was accomplished by constructing a yeast strain overproducing FTase approx. 100-fold. The purified enzyme was a heterodimer of approx. 90 kDa and consisted of 43 kDa and 34 kDa subunits. The 43 kDa subunit was shown to be the product of the DPR1 gene by using antibody raised against baculovirus-produced DPR1 polypeptide. The purified enzyme required Mg2+, showed a pH optimum of 7.8 and was most active at 50 degrees C. The Km values for farnesyl pyrophosphate and GST-CIIS (glutathione S-transferase fused to the C-terminal 12 amino acids of yeast RAS2 protein), KmFpp and KmGST CIIS, were 8.1 and 5.1 microM respectively. The enzyme was capable of farnesylating GST-CIIL (the same as GST-CIIS, except that the C-terminal serine is changed to leucine), a substrate protein for the enzyme geranylgeranyltransferase, although with a higher apparent Km than for GST-CIIS. Like its mammalian counterpart, yeast FTase activity was inhibited by peptides containing the C-terminal CAAX sequence (that is, one where C = cysteine, A = aliphatic amino acid and X = any amino acid). These results provide direct evidence for the idea that the yeast and mammalian FTases are structurally and functionally very similar.

Alkyl and Aryl Transferases↗

PubMed1993

Maturation-dependent regulation of protein kinase C activity by vitamin D3 metabolites in chondrocyte cultures.

Vitamin D3 metabolites regulate the differentiation of chondrocytes isolated from the growth zone or resting zone of rat costochondral cartilage. Since some of the direct membrane effects of vitamin D metabolites are nongenomic, we hypothesized that protein kinase C (PKC) plays a role in signal transduction for these chondrocyte differentiation factors and that the regulation of PKC by the vitamin D metabolites is cell maturation dependent. Confluent, fourth passage cultures of growth zone and resting zone chondrocytes were treated with vitamin D3 metabolites for up to 24 h, lysed, and cell extracts assayed for kinase activity using a specific PKC substrate peptide. The addition of 1,25-(OH)2D3 to growth zone cell cultures resulted in a rapid dose-dependent stimulation of PKC, significant at 10(-9)-10(-7) M, beginning at 3 min and sustained until 90 min; 1,25-(OH)2D3 had no effect on PKC activity in resting zone chondrocyte cultures. The addition of 24,25-(OH)2D3 to resting zone cultures showed a slower PKC activation, with significant stimulation seen at 90-360 min for 10(-8)-10(-7) M 24,25-(OH)2D3. However, 24,25-(OH)2D3 had no effect on PKC activity in growth zone cell cultures at all times and concentrations examined. The specificity of PKC stimulation by the vitamin D3 metabolites was verified using a specific pseudosubstrate region peptide inhibitor, which reduced PKC activity when included in the reaction mixture. Pretreatment of the cultures with U73, 122, a phospholipase C inhibitor, decreased 1,25-(OH)2D3-stimulated PKC activity but had no effect upon 24,25-(OH)2D3-induced activity. The tyrosine kinase inhibitor, genistein, did not inhibit the PKC response in either vitamin D3 metabolites-treated culture. Neither actinomycin D nor cycloheximide affected 1,25-(OH)2D3-induced PKC activity in growth zone chondrocyte cultures, while both compounds inhibited 24,25-(OH)2D3-induced activity in resting zone chondrocyte cultures. The results of this study indicate that vitamin D metabolites stimulate PKC activity in a metabolite- and cell-maturation-specific manner. Effects of 1,25-(OH)2D3 appear to be nongenomic, whereas the effects of 24,25-(OH)2D3 probably involve a genomic mechanism.

24,25-Dihydroxyvitamin D 3↗

PubMed1993

Motility and intraluminal pressure of the ileocolonic junctional zone and adjacent bowel in a canine model.

The exact role of the ileocecal valve (ICV) at the junction of small and large bowel is not well understood. Bowel segments used for the construction of urinary reservoirs incorporate the ICV. In the Indiana pouch its natural continence is used as one principle for achieving continence of the efferent limb. Motor activity and pressure in the ICV, the ileum and colon were registered in eight dogs. Myogenic activity of the bowel consisted of slow waves, irregular spontaneous contractions and superimposed spikes. Pressures of 7.2 +/- 0.3 cmH2O were recorded in the ileum and of 5.6 +/- 0.4 cmH2O in the colon. The pressure in the ICV was 12.7 +/- 0.4 cmH2O rising to 26.4 +/- 2.2 cmH2O during spontaneous depolarization. Balloon dilatation of the ileum resulted in relaxation of the ICV in 76% of experiments, whereas colonic distension was followed by a pressure increase in the ICV region in 80% of experiments. In 16% of cases a relaxation of the ICV area and a weaker response after repeated dilatation was noted. These findings make the ICV an unreliable continence mechanism as its long-term continence can not be predicted despite intraoperative evaluation. Additional measures to ensure consistent continence at the ICV (e.g. electric stimulation) need to be studied.

Animals↗

PubMed1993

Stimulated pressure response of the ileocolonic junctional zone and its use as a continence mechanism in a canine model.

Mechanisms for maintaining passive continence in the efferent limb of urinary diversions include compression of tissue, peristalsis, equilibration of pressure and use of valves. Motor activity and pressure in the ileum, ileocecal valve (ICV) and the colon were evaluated in dogs. Spontaneous activity and pressure were compared with stimulated pressure response and activity. Stimulation was performed at the pelvic nerve and the small nerves in the mesenterium, as well as direct neurostimulation of the bowel. Resting pressure at the ICV was 12.7 +/- 0.4 cmH2O rising to 26.4 +/- 2.2 cmH2O during spontaneous depolarization. Stimulation of the pelvic nerve resulted in increased colonic motor activity with unchanged pressure. Electric stimulation of small mesenterical nerves to the ICV increased pressure in the ICV to 35.0 +/- 4.1 cmH2O, while direct myoelectric stimulation of the ICV zone increased the intraluminal pressure to 75.0 +/- 3.2 cmH2O. Termination of the electric stimulation was followed by a slow decrease of pressure to the resting level over a period of 30-45 s. Maintaining continence at the ICV with long-term constant or intermittent stimulation seems feasible.

Animals↗

PubMed1993

The diagnostic and prognostic value of amniotic fluid white blood cell count, glucose, interleukin-6, and gram stain in patients with preterm labor and intact membranes.

OBJECTIVE: Our goal was to compare the value of amniotic fluid tests in the detection of microbial invasion of the amniotic cavity and in the relationship with the amniocentesis-to-delivery interval and neonatal complications in patients with preterm labor and intact membranes. STUDY DESIGN: Amniotic fluid was retrieved by transabdominal amniocentesis from 120 patients with preterm labor and intact membranes. Fluid was cultured for aerobic and anaerobic bacteria and for mycoplasmas. Amniotic fluid analysis included a Gram stain, white blood cell count, glucose and interleukin-6 determinations. Logistic regression and Cox's proportional hazards model were used for analysis. RESULTS: (1) The prevalence of positive amniotic fluid cultures was 9.2% (11/120); (2) patients with microbial invasion had a shorter amniocentesis-to-delivery interval and a higher neonatal complications rate than patients with a negative culture; (3) the most sensitive test for the detection of microbial invasion of the amniotic cavity was amniotic fluid interleukin-6 determinations (cutoff 11.3 ng/ml) (sensitivity; for interleukin-6 100%, for glucose 81.8%, for white blood cell count 63.6%, and for Gram stain 63.6%; p < 0.05 for all comparisons); (4) the most specific test was the Gram stain of amniotic fluid (specificity: for Gram stain 99.1%, for white blood cell count 94.5%, for interleukin-6 82.6%, and for glucose 81.6%; p < 0.01 for all); (5) of all amniotic fluid tests, interleukin-6 determinations were the only ones that had significant relationship with the amniocentesis-to-delivery interval and neonatal complications. CONCLUSION: Interleukin-6 concentrations in amniotic fluid are better indicators of microbial invasion of the amniotic cavity, amniocentesis-to-delivery interval, and neonatal complications than the amniotic fluid Gram stain, glucose concentration, or white blood cell count.

Adult↗

PubMed1993

A comparative study of the diagnostic performance of amniotic fluid glucose, white blood cell count, interleukin-6, and gram stain in the detection of microbial invasion in patients with preterm premature rupture of membranes.

OBJECTIVE: Our aim was to compare the value of amniotic fluid tests for the detection of microbial invasion of the amniotic cavity and in the prediction of the amniocentesis-to-delivery interval and neonatal complications in patients with preterm premature rupture of membranes. STUDY DESIGN: Amniotic fluid was obtained by transabdominal amniocentesis from 110 consecutive patients with preterm premature rupture of membranes. Fluid was cultured for aerobic and anaerobic bacteria, as well as mycoplasmas. Amniotic fluid analysis included a Gram stain examination, white blood cell count, and glucose and interleukin-6 determinations. Logistic regression and survival techniques (proportional hazards model) were used for statistical analysis. RESULTS: (1) The prevalence of positive amniotic fluid cultures in patients with preterm premature rupture of membranes was 38% (42/110); (2) patients with microbial invasion had a shorter amniocentesis-to-delivery interval and a higher neonatal complication rate than patients with negative cultures; (3) the most sensitive test for the detection of microbial invasion of the amniotic cavity was amniotic fluid interleukin-6 determinations (cutoff 7.9 ng/ml) (sensitivity: for IL-6 80.9%; for white blood cell count 57.1%; for glucose 57.1%; for Gram stain 23.8%; p < 0.05 for all comparisons); (4) the most specific test for the detection of microbial invasion was the Gram stain of amniotic fluid (specificity: for Gram stain 98.5%; for white blood cell count 77.9%; for interleukin-6 75%; for glucose 73.5%; p < 0.01 for all); (5) of all amniotic fluid tests, interleukin-6 determination was the only test that had significant clinical value in the prediction of the amniocentesis-to-delivery interval and neonatal complications. CONCLUSION: Interleukin-6 concentrations in amniotic fluid are a better predictor of microbial invasion of the amniotic cavity, amniocentesis-to-delivery interval and neonatal complications than the amniotic fluid Gram stain, glucose, or white blood cell count in patients with preterm premature rupture of membranes.

Amniocentesis↗