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R C Miller

Publications and source records attributed to R C Miller.

At least 109 records · Page 6Linked to original sources
PubMed1991

Endothelins: functional and autoradiographic studies in guinea pig trachea.

The presence of binding sites for [125I]endothelin-1 and the contractile activities of endothelins (ETs) and sarafotoxin S6b and the endothelin fragment ET(16-21) were investigated in guinea pig trachea. ETs and sarafotoxin S6b (0.1-100 nM) induced potent contractile responses in guinea pig trachea with EC50 values ranging from 1.57 to 12.97 nM. Epithelium removal increased the potencies of ET-1, ET-2 and S6b, but not that of ET-3, and maximal responses to ET-1 and ET-2 were also increased. Effects of epithelium removal were partially mimicked by phosphoramidon (10 microM), an enkephalinase inhibitor, suggesting that enkephalinase (EC.3.4.24.11.) is able to degrade ET-1 and ET-2. ET-3-induced contractions were not affected by phosphoramidon. Autoradiographic studies suggested the presence of at least two specific binding sites for [125]ET-1 in guinea pig airway smooth muscle. The correlation between Kd and EC50 values suggests that the binding sites identified in the airway smooth muscle represent functional receptors for ETs. ET(16-21) and ET(16-21)-NH2 were less potent agonists than the ETs in guinea pig trachea and 10 microM ET(16-21) was unable to inhibit [125I]ET-1 binding in guinea pig airway smooth muscle. Therefore, these results suggest that the C-terminal hexapeptide of ET-1 cannot be used to classify ET receptors in guinea pig trachea.

Animals↗
PubMed1991

Deletion of the linker connecting the catalytic and cellulose-binding domains of endoglucanase A (CenA) of Cellulomonas fimi alters its conformation and catalytic activity.

The Pro-Thr box is a linker of 23 amino acids ((PT)4T(PT)7) connecting the catalytic domain and the cellulose-binding domain (CBD) of endoglucanase A (CenA) from the bacterium Cellulomonas fimi. Deletion of the Pro-Thr box alters the conformation of CenA by changing the relative orientation of the catalytic domain and the CBD. The tertiary structures of the catalytic domain and the CBD appear to be unchanged. The change in conformation reduces the catalytic efficiency of the enzyme and masks one of two protease-sensitive sites between the domains. The deletion does not affect the adsorption of the enzyme to microcrystalline cellulose, but it does affect its desorption from cellulose. The results suggest that the Pro-Thr box in CenA has an extended, kinked, and rigid conformation.

Actinomycetales↗
PubMed1991

The clinical implications of subchorionic placental lucencies.

Forty-six patients were identified at a perinatal diagnostic referral center as having subchorionic placental lucencies. These lucencies varied from simple to multicystic and covered up to 50% of the subchorionic placental surface. Clinical follow-up of 40 patients demonstrated no increase in the incidence of adverse pregnancy outcome. We conclude that these pregnancies are not at higher risk when the subchorionic placental lucencies are not associated with other intraplacental or fetal anomalies.

Chorion↗
PubMed1991

Enzyme immobilization using a cellulose-binding domain: properties of a beta-glucosidase fusion protein.

Using molecular genetic techniques, a fusion protein has been produced which contains the cellulose-binding domain (CBD) of an exoglucanase (Cex) from Cellulomonas fimi fused to a beta-glucosidase (Abg) from Agrobacterium sp. The CBD functions as an affinity tag for the simultaneous purification and immobilization of the enzyme on cellulose. Binding to cellulose was stable for prolonged periods at temperatures from 4 degrees C to at least 50 degrees C, at ionic strengths from 10 mM to greater than 1 M, and at pH values below 8. The fusion protein can be desorbed from cellulose with distilled water or at pH greater than 8. Immobilized enzyme columns of the fusion protein bound to cotton fibers exhibited stable beta-glucosidase activity for at least 10 days of continuous operation at temperatures up to 37 degrees C. At higher temperatures, the bound enzyme lost activity. The thermal stability of the fusion protein was greatly improved by immobilization. Immobilization did not alter the pH stability. Except for its ability to bind to cellulose, the properties of the fusion protein were virtually the same as those of the native enzyme.

Adsorption↗
PubMed1991

Nucleotide sequence of the endoglucanase C gene (cenC) of Cellulomonas fimi, its high-level expression in Escherichia coli, and characterization of its products.

The cenC gene of Cellulomonas fimi, encoding endoglucanase CenC, has an open reading frame of 1101 codons closely followed by a 9 bp inverted repeat. The predicted amino acid sequence of mature CenC, which is 1069 amino acids long, is very unusual in that it has a 150-amino-acid tandem repeat at the N-terminus and an unrelated 100-amino-acid tandem repeat at the C-terminus. CenC belongs to subfamily E1 of the beta-1,4-glycanases. High-level expression in Escherichia coli of cenC from a 3.6 kbp fragment of C. fimi DNA leads to levels of CenC which exceed 10% of total cell protein. Most of the CenC is in the cytoplasm in an inactive form. About 60% of the active fraction of CenC is in the periplasm. The catalytic properties of the active CenC are indistinguishable from those of native CenC from C. fimi. The Mr of CenC from E. coli and C. fimi is approximately 130 kDa. E. coli and C. fimi also produce an endoglucanase, CenC', of approximate Mr 120kDa and with the same N-terminal amino acid sequence and catalytic properties as CenC. CenC' appears to be a proteolytic product of CenC. CenC and CenC' can bind to cellulose and to Sephadex. CenC is the most active component of the C. fimi cellulase system isolated to date.

Amino Acid Sequence↗
PubMed1991

Modulation by endothelium of the responses induced by endothelin-1 and by some of its analogues in rat isolated aorta.

1. The contractile effects of endothelin-1 and various analogues were studied in rat isolated rings. The potency of the peptides studied was endothelin-1 greater than sarafotoxin S6b greater than [Ala3,11]endothelin-1 greater than [Ala1,15]endothelin-1. [Ala1,3,11,15]endothelin-1 was neither agonist nor antagonist. 2. The concentration of endothelin-1 required to induced contractions equal to 50% of those induced by 1 microM noradrenaline was reduced from 5.8 nM when the vascular endothelium was present to 1.4 nM after it had been mechanically removed. 3. Contractions elicited by [Ala3,11]endothelin-1, [Ala1,15]endothelin-1 and sarafotoxin S6b were not modulated by the endothelium. 4. Endothelin-1 increased the tissue content of guanosine 3',5'-cyclic monophosphate (cyclic GMP) in rat aortic segments with endothelium by about 4 fold, suggesting that it increased the release of endothelium-derived relaxing factor. Sarafotoxin S6b did not reduce, or significantly increase, tissue cyclic GMP levels and therefore had little effect on EDRF release. 5. The concentration of sodium nitroprosside required to relax half-maximally aortae denuded of endothelium was 430 nM if the aortae had been precontracted with 10 nM endothelin-1 and 35 nM if 10 nM sarafotoxin S6b was used as the spasmogen. This indicates that differential sensitivities of the smooth muscle to cyclic GMP cannot explain differences between responses to endothelin-1 and sarafotoxin S6b in the presence of endothelium. 6. It is concluded that endothelin-1 contractions of rat aorta are modified by the endothelium, probably by enhancing the release of endothelium-derived relaxing factor (EDRF) and not by affecting the sensitivity of the smooth muscle to EDRF. This suggests that a stimulated release of an adequate amount of EDRF is necessary to modulate contractile responses to these peptides.

Animals↗
PubMed1991

Multiple pyogenic granulomata in childhood.

Multiple pyogenic granulomata are rare. Satellite lesions are infrequently associated with trauma to or treatment of the primary lesion. Rare cases of disseminated pyogenic granulomata have been reported. We report the occurrence of numerous, discrete, pyogenic granulomata in two young boys at locations remote from the primary excision site, and review the literature on multiple pyogenic granulomata. In patient no. 1, new lesions seemed to develop from 2- to 4-mm capillary hemangiomas both within and outside of a port-wine stain. Patient no. 2 involves a previously unreported occurrence of numerous facial lesions.

Child↗
PubMed1991

The role of the disulphide bonds in endothelin-1.

The smooth muscle contracting peptide endothelin-1 is characterized by the presence of two disulphide bonds and their importance for maintaining the agonist activity of the peptide was examined by synthesizing analogues of endothelin-1 lacking one or the other, or both, of these bonds. The circular dichroic spectra of these analogues (in which alanine residues replaced the appropriate cystines), [Ala1,15]-, [Ala3,11]- and [Ala1,3,11,15]-endothelin-1 had features in common with that of endothelin-1. All three analogues exhibited at least some agonist activity in guinea-pig isolated trachea, but surprisingly endothelin-1 was a partial agonist in comparison with the analogue [Ala3,11]endothelin-1. The disulphide bonds are therefore not absolutely essential for maintaining the tertiary structure necessary for agonist activity at endothelin-1 receptors in all tissues.

Amino Acid Sequence↗
PubMed1991

Unusual sequence organization in CenB, an inverting endoglucanase from Cellulomonas fimi.

The nucleotide sequence of the cenB gene was determined and used to deduce the amino acid sequence of endoglucanase B (CenB) of Cellulomonas fimi. CenB comprises 1,012 amino acids and has a molecular weight of 105,905. The polypeptide is divided by so-called linker sequences rich in proline and hydroxyamino acids into five domains: a catalytic domain of 607 amino acids at the N terminus, followed by three repeats of 98 amino acids each which are greater than 60% identical, and a C-terminal domain of 101 amino acids which is 50% identical to the cellulose-binding domains of C. fimi cellulases Cex and CenA. A deletion mutant of the cenB gene encodes a polypeptide lacking the C-terminal 333 amino acids of CenB. The truncated polypeptide is catalytically active and, like intact CenB, binds to cellulose, suggesting that CenB has a second cellulose-binding site. The sequence of amino acids 1 to 461 of CenB is 35% identical, with a further 15% similarity, to that of a cellulase from avocado, which places CenB in cellulase family E. CenB releases mostly cellobiose and cellotetraose from cellohexaose. Like CenA, CenB hydrolyzes the beta-1,4-glucosidic bond with inversion of the anomeric configuration. The pH optimum for CenB is 8.5, and that for CenA is 7.5.

Amino Acid Sequence↗
PubMed1991

Multiple domains in endoglucanase B (CenB) from Cellulomonas fimi: functions and relatedness to domains in other polypeptides.

Endoglucanase B (CenB) from the bacterium Cellulomonas fimi is divided into five discrete domains by linker sequences rich in proline and hydroxyamino acids (A. Meinke, C. Braun, N. R. Gilkes, D. G. Kilburn, R. C. Miller, Jr., and R. A. J. Warren, J. Bacteriol. 173:308-314, 1991). The catalytic domain of 608 amino acids is at the N terminus. The sequence of the first 477 amino acids in the catalytic domain is related to the sequences of cellulases in family E, which includes procaryotic and eucaryotic enzymes. The sequence of the last 131 amino acids of the catalytic domain is related to sequences present in a number of cellulases from different families. The catalytic domain alone can bind to cellulose, and this binding is mediated at least in part by the C-terminal 131 amino acids. Deletion of these 131 amino acids reduces but does not eliminate activity. The catalytic domain is followed by three domains which are repeats of a 98-amino-acid sequence. The repeats are approximately 50% identical to two repeats of 95 amino acids in a chitinase from Bacillus circulans which are related to fibronectin type III repeats (T. Watanabe, K. Suzuki, K. Oyanagi, K. Ohnishi, and H. Tanaka, J. Biol. Chem. 265:15659-15665, 1990). The C-terminal domain of 101 amino acids is related to sequences, present in a number of bacterial cellulases and xylanases from different families, which form cellulose-binding domains (CBDs). It functions as a CBD when fused to a heterologous polypeptide. Cells of Escherichia coli expressing the wild-type cenB gene accumulate both native CenB and a stable proteolytic fragment of 41 kDa comprising the three repeats and the C-terminal CBD. The 41-kDa polypeptide binds to cellulose but lacks enzymatic activity.

Amino Acid Sequence↗
PubMed1991

Small differences in Drosophila tropomyosin expression have significant effects on muscle function.

The effects of promoter deletions on Drosophila tropomyosin I (TmI) gene expression have been determined by measuring TmI RNA levels in transformed flies. Decreases in RNA levels have been correlated with rescue of flightless and jumpless mutant phenotypes in Ifm(3)3 mutant transformed flies and changes in muscle ultrastructure. The results of this analysis have allowed us to identify a region responsible for 20% of maximal TmI expression, estimate threshold levels of TmI RNA required for indirect flight and jump muscle function, and obtain evidence suggesting that sarcomere length may be an important determinant of flight muscle function.

Animals↗
PubMed1991

Domains in microbial beta-1, 4-glycanases: sequence conservation, function, and enzyme families.

Several types of domain occur in beta-1, 4-glycanases. The best characterized of these are the catalytic domains and the cellulose-binding domains. The domains may be joined by linker sequences rich in proline or hydroxyamino acids or both. Some of the enzymes contain repeated sequences up to 150 amino acids in length. The enzymes can be grouped into families on the basis of sequence similarities between the catalytic domains. There are sequence similarities between the cellulose-binding domains, of which two types have been identified, and also between some domains of unknown function. The beta-1, 4-glycanases appear to have arisen by the shuffling of a relatively small number of progenitor sequences.

Amino Acid Sequence↗
PubMed1991

Endothelin receptor heterogeneity; structure activity, autoradiographic and functional studies.

Radioligand binding studies were used to define the binding constants for inhibition of [125I]endothelin-1 binding by endothelin-1 (ET-1), endothelin-3 (ET-3) and a synthetic analogue of ET-1, [Ala1,3,11,15]ET-1 in rat aorta and cerebellum. The inhibition curves for the three substances were similar in the cerebellum (Ki, ET-1 = ET-3 = [Ala1,3,11,15]ET-1) but differed in the aorta (Ki, ET-1 much less than [Ala1,3, 11,15]ET-1) with the ET-3 inhibition curves being biphasic, indicating binding to two sites. In functional studies in the aorta, in contrast to findings in the cerebellum, [Ala1,3,11,15]ET-1 was inactive and ET-3 was a partial agonist. These findings support the idea of heterogeneity of endothelin receptors. Autoradiographic studies were performed to identify the cellular localisation of endothelin-1 receptors in the two tissues. In the aorta binding was to all elements of the vasculature including the endothelium, smooth muscle, periadventitial connective tissue and nerves. In the cerebellum binding sites were located predominantly over the neuronal elements of the granular cell layer. The cellular localisation of the high and low affinity sites for ET-3, and the functional significance of the high affinity binding site for ET-3, remain to be determined.

Animals↗
PubMed1991

Extremely high maternal serum alpha-fetoprotein levels at second-trimester screening.

Maternal serum alpha-fetoprotein (MSAFP) screening is widely used for the detection of open neural tube defects (NTDs) and a variety of other anomalies and complications. We examined the outcomes of 44 pregnancies with MSAFP elevations of 8 or more multiples of the median (MoM) from among 40,676 screened pregnancies. At the initial evaluation by ultrasound, 82% of the patients had at least one finding that may have accounted for the elevation. Approximately 45% of the fetuses had a major fetal anomaly, 25% died, 16% had an identifiable placental abnormality, and 5% had an underestimation of gestational age; 18% of the elevations remained unexplained after ultrasound. In follow-up of the pregnancies, all of those with an unexplained elevation after initial ultrasound had at least one obstetric complication or placental abnormality. The overall positive predictive value of an MSAFP value of 8 or more MoM for NTDs was 22.7%. The proportion of infants born alive in the overall group was low, with only 16 live births among 46 fetuses. The majority of the nonviable outcomes were associated with a fetus with a major anomaly that was terminated or died before 20 weeks. Of the live-born infants, 31% had a major anomaly, 19% had intrauterine growth retardation (IUGR) and an anomaly, 12.5% had IUGR without an anomaly, and 25% were preterm. Eighty-eight percent of those pregnancies with a live-born infant had at least one obstetric complication. Among pregnancies with MSAFP of 8 or more MoM, the majority are associated with large structural fetal anomalies or fetal death before 20 weeks.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Bacterial cellulose-binding domain-like sequences in eucaryotic polypeptides.

The catalytic domain of endoglucanase II of Trichoderma reesei and the spore germination-specific polypeptide 270-11 of Dictyostelium discoideum contain amino acid sequences which share identity with the sequences of the cellulose-binding domains of several bacterial beta-1,4-glycanases. This is the first report of the presence of such sequences in eucaryotic polypeptides.

Amino Acid Sequence↗
PubMed1991

Pulmonary embolization of a vascular ligature clip as a complication of para-aortic lymph node sampling.

A case is reported of a 57-year-old woman who underwent cytoreductive surgery for stage III, grade 2 endometrioid cystadenocarcinoma of the ovary. During para-aortic lymph node sampling, hemostasis was achieved with medium and small metallic ligature clips. The immediate postoperative period was uneventful and the chest radiograph was unchanged from preoperative film. On the sixth postoperative day a chest radiograph showed a radio-opaque object consistent with a metallic ligature clip in the peripheral left middle lung field. The remaining postoperative course was uncomplicated and the patient is well 14 months postoperatively; the ligature clip is unchanged in position. This is an interesting and previously unreported complication of para-aortic lymph node sampling. The means by which the clip entered the vascular system is unknown. Nonsurgical removal of the clip was not feasible due to its peripheral location. No studies exist as to the long-term outcome of foreign bodies embolized to the peripheral lung.

Cystadenocarcinoma↗
PubMed1991

Immune thrombocytopenic purpura in pregnancy: a reappraisal of management.

Management and, particularly, mode of delivery of the pregnant patient with immune thrombocytopenic purpura (ITP) are controversial. We reviewed our experience with 31 pregnancies in 25 women with ITP over a 10-year period. Fourteen infants were born vaginally and 18 by cesarean. Six major complications occurred among mothers delivered by cesarean, whereas none occurred among those born vaginally (P = .028). Three of 32 infants were born with moderate thrombocytopenia (platelet count 51-100 x 10(9)/L) and two with severe thrombocytopenia (platelet count 50 x 10(9)/L or less); there were no clinically significant complications in these infants. No maternal characteristic could be used to predict the neonatal platelet count. In an analysis of 474 infants of mothers with ITP reported in the literature and including the present series, 10% were born with moderate thrombocytopenia and 15% with severe thrombocytopenia. The overall rate of intracranial hemorrhage in newborns with moderate or severe thrombocytopenia was 3%. No significant association was found between the rate of intracranial hemorrhage and delivery mode for moderately and severely thrombocytopenic neonates together (weighted odds ratio 1.69, 95% confidence interval 0.14-44.6) or for those with severe thrombocytopenia (crude odds ratio 1.38, 95% confidence interval 0.07-84.67). We conclude that the mode of delivery may not affect the rate of intracranial hemorrhage in thrombocytopenic newborns.

Delivery, Obstetric↗