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Biomedical subjects

K Shaw

Publications and source records attributed to K Shaw.

At least 73 records · Page 4Linked to original sources
PubMed1995

Low-dose aspirin in nulliparous women: safety of continuous epidural block and correlation between bleeding time and maternal-neonatal bleeding complications. National Institute of Child Health and Human Developmental Maternal-Fetal Medicine Network.

OBJECTIVE: Our purpose was to determine the frequency and safety of the use of epidural anesthesia and the correlation between bleeding time and maternal-neonatal bleeding complications in a group of pregnant women who participated in a multicenter trial of low-dose aspirin in pregnancy. STUDY DESIGN: Data regarding type of anesthesia used for labor and delivery were available in 1629 nulliparous women who were randomly assigned at 13 to 27 weeks to receive 60 mg/day aspirin or a placebo. A total of 891 (55%) received epidural anesthesia, and the remaining 738 did not. RESULTS: Among the 891 women known to have received epidural anesthesia, 451 were assigned to low-dose aspirin and 440 to placebo. There was no instance of bleeding related to epidural use. In addition, there were no differences in maternal and neonatal complications between those receiving or not receiving epidural anesthesia. Within the group receiving epidural anesthesia there were no differences in bleeding complications between those assigned to aspirin on placebo. One of the five centers also obtained bleeding times in 303 women (149 received aspirin and 154 received placebo). The mean +/- SD bleeding time in women assigned to low-dose aspirin was significantly higher than in women assigned to placebo (6.99 +/- 2.95 minutes vs 5.99 +/- 2.43 minutes, p = 0.004). In addition, the frequency of women having a bleeding time > 10 minutes was higher in the aspirin group (14.1% vs 5.2%, p = 0.01). Interestingly, women who received an epidural anesthetic had a lower bleeding time than those not receiving an epidural (p = 0.003), irrespective of the treatment used. CONCLUSIONS: In women assigned to low-dose aspirin there were no adverse effects related to epidural anesthesia. In spite of an increased bleeding time in a subset of pregnant women assigned to low-dose aspirin, maternal-neonatal bleeding complications were not increased.

Analysis of Variance↗
PubMed1995

The outcome of macrosomic infants weighing at least 4500 grams: Los Angeles County + University of Southern California experience.

OBJECTIVE: To describe the maternal and neonatal outcome of macrosomic infants weighing at least 4500 g. METHODS: Maternal and neonatal records of infants with birth weights of at least 4500 g were identified during 1991. Outcome variables included the mode of delivery and incidence of maternal and perinatal complications. RESULTS: The study sample consisted of 227 infant and mother pairs. Mean (+/- standard deviation) birth weight was 4706 +/- 219 g. A trial of labor was allowed in 192 women, and elective cesarean delivery was performed in 35 patients. The overall cesarean rate, including elective cesarean delivery and failed trial of labor, was 30.8% (70 of 227). Of those undergoing a trial of labor, 82% (157) delivered vaginally. Shoulder dystocia occurred 29 times, for an incidence of 18.5% in vaginal deliveries for macrosomia. There were seven cases each of Erb palsy and clavicular fracture, and one humeral fracture. By 2 months of age, all affected infants were without permanent sequelae. There was no birth asphyxia or perinatal mortality related to delivery for macrosomia. Maternal complications included increased risk of lacerations requiring repair (especially third- or fourth-degree lacerations) when vaginal delivery was complicated by shoulder dystocia (relative risk [RR] 5.4, 95% confidence interval [CI] 3.1-9.4). There was no statistically significant difference with respect to hemorrhage or hospital stay for women who had a vaginal delivery (with or without shoulder dystocia) compared with women who had a cesarean delivery. However, infectious morbidity increased significantly in those patients who underwent a cesarean after a trial of labor compared with women who had a vaginal delivery (RR 7.1, 95% CI 3.9-13.1) or elective cesarean birth (RR 5.4, 95% CI 3.1-9.4). Ninety-one percent of patients undergoing elective cesarean delivery had no complications. CONCLUSION: Vaginal delivery is a reasonable alternative to elective cesarean for infants with estimated birth weights of at least 4500 g, and a trial of labor can be offered.

Adolescent↗
PubMed1994

Synthetic, structural and biological studies of the ubiquitin system: the total chemical synthesis of ubiquitin.

The small protein ubiquitin (76 amino acids) has been synthesized under optimized conditions by Merrifield solid-phase methodology using the N alpha-Fmoc protecting group. The crude polypeptide mixture was purified to homogeneity by gel filtration, dialysis and a combination of cation- and anion-exchange chromatography to yield ubiquitin. Amino acid analysis, enzymic digestion and sequencing by automated Edman degradation were used to authenticate the primary structure. Isoelectric focusing and m.s. were used to demonstrate that the final product was greater than 98% pure with a final yield of 93 mg (4.3%) from a single synthesis on a 0.25 nmol scale.

Amino Acid Sequence↗
PubMed1994

Characterization of a replicating and packaged defective RNA of avian coronavirus infectious bronchitis virus.

The Beaudette strain of IBV was passaged 16 times in chick kidney cells. Total cellular RNA was analyzed by Northern hybridization and was probed with 32P-labeled cDNA probes corresponding to the first 2 kb of the 5' end of the genome, but excluding the leader, and to the last 1.8 kb of the 3' end of the genome. A new, defective IBV RNA species (CD-91) was detected at passage 6. The defective RNA, present in total cell extract RNA and in oligo-(dT)30-selected RNA from passage 15, was amplified by the reverse transcription-polymerase chain reaction (RT-PCR) to give four fragments. The oligonucleotides used were selected such that CD-91 RNA, but not the genomic RNA, would be amplified. Cloning and sequencing of the PCR products showed that CD-91 comprises 9.1 kb and has three regions of the genome. It contains 1133 nucleotides from the 5' end of the genome, 6322 from gene 1b corresponding to position 12,423 to 18,744 in the IBV genome, and 1626 from the 3' end of the genome. At position 749 one nucleotide, an adenine residue, was absent from CD-91 RNA. By Northern hybridization CD-91 RNA was detected in virions in higher amounts than the subgenomic mRNAs.

Base Sequence↗
PubMed1994

Impairment of nutrient uptake in a rabbit model of gastroschisis.

Infants with gastroschisis (GS) commonly require total parenteral nutrition and prolonged hospitalization because of intestinal dysfunction resulting from dysmotility and/or malabsorption. To investigate prepartum small intestinal (SI) nutrient absorption in GS, a fetal rabbit model was surgically created on gestational day 24 (term, 31 to 33 days) in 11 time-mated New Zealand White does in each left ovarian-end fetus. Each right ovarian-end fetus served as a control (C) and was manipulated only. All does, 10 of 11 GS fetuses (91%), and 8 of 11 C fetuses (73%) survived to gestational day 30. GS fetuses had significantly reduced total body weights, SI weights, and SI lengths compared with C fetuses. Using the everted mucosal sleeve technique, the uptakes of an amino acid (proline) and a sugar (glucose) were determined. The uptakes of proline per milligram SI, proline per centimeter SI, and glucose per milligram SI were significantly impaired in GS fetuses compared with C fetuses (P < .04 by Student's paired t test). The uptake of glucose per centimeter SI was also reduced in GS fetuses, but not significantly. Uptake capacities (a measure of the entire SI's ability to absorb a given nutrient) were significantly reduced in GS fetuses compared with C fetuses (proline, 2,670 +/- 612 nmol/min/entire SI v 6,842 +/- 399 nmol/min/entire SI, P < .008 by Student's paired t test; glucose, 402 +/- 69 nmol/min/entire SI v 950 +/- 103, P < .008 by Student's paired t test).

Abdominal Muscles↗
PubMed1994

Report of three gastric tumors in children.

The literature concerning gastric tumors in children is mainly limited to case studies. The authors reviewed 1,403 histological reports of pediatric gastric pathology (covering 10 years) at their institution. There were three gastric tumors of benign histology and no malignant tumors. The first patient was a 9 1/2-year-old boy who presented with several months of symptomatic, pH-probe-confirmed gastroesophageal reflux. He underwent placement of a Toupet antireflux valve. During laparotomy, a submucosal mass was discovered incidentally, on the greater curvature of the stomach. The mass was excised. Pathological examination showed heterotopic pancreas. The second patient, a 15-month-old girl, presented with a short period of vomiting. Results of an upper gastrointestinal series showed gastric outlet obstruction. She underwent laparotomy and was found to have an intussusception of a gastric polyp into the proximal jejunum, and an associated malrotation. Ladd's procedure, gastroduoduodenostomy with reduction of the intussuscepted polyp, and excision of the polyp were performed. Histological examination of the tumor showed hamartoma with hyperplastic elements. The tumor was benign but was regarded as difficult to classify. The third patient, a 6-year-old boy, presented with microcytic anemia. Endoscopy showed multiple friable bleeding gastric masses. He underwent laparotomy, with partial gastrectomy and pyloroplasty. Histological examination showed the tumor to be plasma cell granuloma. The tumor recurred, and the patient required subsequent operative procedures. The authors confirm that gastric tumors in children are rare. Although the tumor histology may be benign, excision of the tumor may require major operative resection.

Child↗
PubMed1994

Agonist-induced desensitization and loss of high-affinity binding sites of stably expressed human 5-HT1A receptors.

Exposure of HeLa cells stably expressing cloned human 5-hydroxytryptamine (5-HT)1A receptors (HA7 cells) to the agonist 8-hydroxy-2-(di-N-propylamino)-tetralin (8-OH-DPAT) results in a loss of high-affinity binding sites and a desensitization of receptor-adenylate cyclase coupling, as measured by 5-HT1A-mediated inhibition of forskolin-stimulated adenylate cyclase activity. These responses can also be observed after exposure to forskolin, which activates cyclic AMP-dependent protein kinase A or after treatment with known activators of protein kinase C (PKC) such as phorbol-12-myristate 13-acetate (PMA). The responses elicited by exposure to 8-OH-DPAT or PMA can be blocked completely by inhibitors of PKC and also by 24-hr exposure to PMA. Preincubation of HA7 cells with 8-OH-DPAT also stimulates hydrolysis of inositol phospholipids and the production of arachidonic acid. Inhibition of phospholipase A2 with quinacrine or by removal of extracellular Ca++ blocks the agonist-mediated loss of 5-HT1A receptor binding sites. These data demonstrate that agonist-induced down regulation of the 5-HT1A receptor occurs after stimulation of both the PKC and phospholipase A2 signaling pathways, both of which may activate PKC. The subsequent response is a loss of high-affinity ligand binding sites and functional receptor coupling to adenylate cyclase.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1993

Purification of a 110-kDa phosphoinositide phospholipase C that is activated by G-protein beta gamma-subunits.

We report the purification from bovine brain cytosol of a 110-kDa phosphoinositide-specific phospholipase C (PLC-110) that was markedly stimulated by G-protein beta gamma-subunits. The enzyme was purified approximately 2000-fold with a yield of 4%. On the basis of size and immunological cross-reactivity, PLC-110 was distinct from 150-kDa PLC-beta 1, 145-kDa PLC-gamma 1, and 85-kDa PLC-delta 1. An antiserum to a peptide corresponding to a conserved PLC Y domain sequence cross-reacted with PLC-110. PLC-110 was also recognized by two antisera selective for NH2-terminal and internal sequences in PLC-beta 3, but not by a third peptide antiserum to the COOH terminus of this enzyme, suggesting that PLC-110 is related to PLC-beta 3. Reconstitution of purified PLC-110 with beta gamma-subunits produced greater than 100-fold activation, indicating activation was observed at approximately 60 nM beta gamma and full activation at approximately 500 nM beta gamma. PLC-110 maximally hydrolyzed phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate at 1 microM Ca2+, but showed no activity toward phosphatidylinositol at Ca2+ concentrations up to 1 mM. Concentrations of purified guanosine 5'-O-(3-thiotriphosphate)-liganded alpha q that fully activated PLC-beta 1 failed to stimulate PLC-110. This observation indicates that the site at which beta gamma interacts with PLC-110 is distinct from that at which alpha q regulates the activity of PLC-beta isozymes.

Animals↗
PubMed1993

Presence of subgenomic mRNAs in virions of coronavirus IBV.

The presence of subgenomic mRNAs in virions of IBV was examined by probing Northern blots of RNA extracted from virions using as a probe a cDNA of the 3'-terminal nucleocapsid protein (N) gene. This detects all five mRNAs because of the 3'-coterminal, nested-set arrangement of coronavirus mRNAs. The mRNAs were readily detected even after extensive purification of virions and after RNase A treatment of virions. In sucrose gradients the peaks of virus particles, genomic RNA (gRNA), and mRNAs were coincident. Cellular mRNA was not detected in virions. The molar ratio of gRNA to each mRNA ranged from about 10 to 30 for IBV-Beaudette and 25 to 800 for IBV-M41. The molar ratio of genomic to intracellular viral mRNAs was also determined. From this it was estimated that the efficiency of incorporation of gRNA into virions was at least 20- to 100-fold greater, depending on the mRNA species, for IBV-Beaudette and 100- to 500-fold for IBV-M41. It is concluded that most virions contain only gRNA or contain only one species of mRNA on average in addition to gRNA.

Animals↗
PubMed1993

Analysis of messenger RNA within virions of IBV.

The presence of subgenomic mRNAs (sgRNAs) in virions of infectious bronchitis virus was examined by probing Northern blots of RNA extracted from virions using as a probe a cDNA of the 3'-terminal nucleocapsid protein (N) gene. The sgRNAs were readily detected even after extensive purification of virions and after RNase A treatment of virions. The molar ratio of gRNA to each sgRNA was in the range 25 to 400 for IBV-M41 and 10 to 30 for IBV-Beaudette. After comparison with the molar ratios of genomic to intracellular viral sgRNAs it was estimated that the efficiency of incorporation of gRNA into virions was approximately 100 to 500-fold greater than for sgRNAs in the case of M41 and 20 to 100-fold for Beaudette, depending on the sgRNA species. It is concluded that sgRNAs can be present within IBV virions. Approximately 1 in 3 Beaudette virions and 1 in 20 M41 particles might contain a single copy of one sgRNA.

Animals↗
PubMed1993

Orbitotemporal neurofibromatosis: classification and treatment.

In localized orbitotemporal neurofibromatosis, the treatment depends very much on the type and severity of the orbital involvement and on the functional state of the eye. The condition can be conveniently divided into three groups, each requiring different treatment: (1) orbital soft-tissue involvement with a seeing eye, (2) orbital soft-tissue and significant bony involvement with a seeing eye, and (3) orbital soft-tissue and significant bony involvement with a blind or absent eye. A total of 24 patients with a maximum of 12 years recurrence-free follow-up are presented.

Adult↗
PubMed1992

Identification in bovine liver plasma membranes of a Gq-activatable phosphoinositide phospholipase C.

Phosphoinositide phospholipase C (PLC) activity extracted from bovine liver plasma membranes with sodium cholate was stimulated by GTP gamma S-activated G alpha q/G alpha 11, whereas the enzyme from liver cytosol was not. The membrane-associated PLC was subjected to chromatography on heparin-Sepharose, Q Sepharose, and S300HR, enabling the isolation of the G-protein stimulated activity and its resolution from PLC-gamma and PLC-delta. Following gel filtration, two proteins of 150 and 140 kDa were found to correspond to the activatable enzyme. These proteins were identified immunologically as members of the PLC-beta family and were completely resolved by chromatography on TSK Phenyl 5PW. The 150-kDa enzyme was markedly responsive to GTP gamma S-activated alpha-subunits of G alpha q/G alpha 11 or to purified Gq/G11 in the presence of GTP gamma S. The response of this PLC was of much greater magnitude than that of the 140-kDa enzyme. The partially purified 150-kDa enzyme showed specificity for PtdIns(4,5)P2 and PtdIns4P as compared to PtdIns and had an absolute dependence upon Ca2+. These characteristics were similar to those of the brain PLC-beta 1. The immunological and biochemical properties of the 150-kDa membrane-associated enzyme are consistent with its being the PLC-beta isozyme that is involved in receptor-G-protein-mediated generation of inositol 1,4,5-triphosphate in liver.

Animals↗
PubMed1992

Characterization of Caramel Colour IV.

A large number of commercial Caramel Colour IV samples were characterized in order to assess the uniformity of the class and to provide data to be used in specifications development. Owing to the chemical and physical complexity of caramel colour it was not feasible to perform detailed analysis of all constituents for assessment of uniformity. Instead, selected parameters were evaluated and judgements were made with respect to compositional uniformity based on the similarities of these parameters among the various samples. As Caramel Colour IV is required by the food industry in a range of colour intensities, there must be a range of properties that differ from sample to sample, but that are sufficiently similar for the material to still be considered as part of the Caramel Colour IV class. Fractions as well as whole caramel were analysed using selected spectrophotometric, chromatographic and chemical techniques. Samples were fractionated based on molecular weight and polarity. The data presented here provide evidence for the uniformity in composition of Caramel Colour IV with respect to molecular weight distribution, to nitrogen and sulphur content and their distribution throughout the fractions, to absorbance properties and to specific low molecular weight compounds. Thus, it can be concluded that Caramel Colour IV exhibits compositional uniformity within the range of colour intensity required by the food industry worldwide.

Candy↗
PubMed1992

Characterization of Caramel Colours I, II and III.

Groups of representative samples of Caramel Colours I, II, and III were characterized in order to assess the compositional uniformity within each class and to determine differences between each class. Compositional uniformity within each class was demonstrated by fractionation of the caramel samples and analysis by UV and visible absorbance, HPLC and chemical analysis. Although there was overlap between certain parameters of one or more caramel colour classes, the overall 'fingerprint' for each class, based on several different parameters, was distinctly unique. Such parameters included net ionic charge, absorbance properties, nitrogen and sulphur content, specific low molecular weight compounds and HPLC profiles. HPLC analysis revealed unique profiles within each class and distinct differences between classes. The data presented here for Caramel Colours I, II, and III, and elsewhere for Caramel Colour IV, indicate that each of the four classes can be considered as separate and that, throughout each class, the samples characterized constitute a homologous series of mixtures in terms of chemical composition.

Candy↗
PubMed1992

Development of specifications for caramel colours.

Specifications have been developed to define each of the four classes of caramel colour. The specifications were based on analysis of a large database generated during the course of characterization studies of each of the classes. A series of simple and practical tests was developed for the analysis of caramel colour samples to ensure conformity to the specifications.

Candy↗
PubMed1991

The sequences of the ribonucleotide reductase genes from African swine fever virus show considerable homology with those of the orthopoxvirus, vaccinia virus.

Two African swine fever virus (ASFV) recombinant plasmids containing large inserts of DNA have been sequenced at random, and translations of the DNA sequence have been compared to libraries of vaccinia virus protein sequences. Among other genes identified by their extensive homology with vaccinia virus genes were the large and small subunits of ribonucleotide reductase. A 5.5-kb fragment from the Malawi (LIL20/1) strain of ASFV was identified as containing the genes for both these subunits. The fragment has been sequenced and the two genes have been found to be in a head-to-head orientation. The sequences are compared to other sequenced ribonucleotide reductase genes, and the evolutionary implications discussed.

African Swine Fever Virus↗