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Biomedical subjects

K Murray

Publications and source records attributed to K Murray.

At least 163 records · Page 9Linked to original sources

Synthesis of yeast histone 3 in an Escherichia coli cell-free system.

The gene for histone H3 from the yeast Saccharomyces cerevisiae was placed under the control of the lac promoter of Escherichia coli by fusing the H3 coding sequence to that of beta-galactosidase. The gene was shown to be transcribed in vivo, but its product was not detected in cell extracts. However, synthesis of the fused polypeptide was detected in an in vitro transcription-translation system derived from E. coli. Proteolytic degradation of the newly synthesized polypeptides may be the cause of their apparent absence in the in vivo experiment.

Amino Acid Sequence↗

6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase from rat liver.

Rat liver 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase was phosphorylated by [gamma-32P]ATP plus fructose-6-P or [2-32P]fructose-2,6-P2. The radioactivity co-migrated with homogeneous 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase during sodium dodecyl sulfate-disc gel electrophoresis and the phosphoenzyme was acid-labile and base-stable. Hydrolysis of the phosphate group from phosphoenzyme prepared with either donor and the hydrolysis of their tryptic phosphopeptides depended on pH similarly. The pH dependence suggested that phosphate was linked to the N3 of a histidine residue. Co-electrophoresis and co-chromatography of alkaline hydrolysates of the labeled phosphoenzyme prepared from either substrate allowed the definitive identification of 3-phosphohistidine in the degradation products. Modification of the enzyme with diethylpyrocarbonate inactivated both the phosphotransferase and phosphohydrolase activities and suppressed the phosphorylation of the enzyme by ATP and fructose-6-P or by fructose-2,6-P2. Trypsin digestion of the phosphoenzyme formed upon incubation with ATP or fructose-2,6-P2 yielded an identical phosphopeptide after high pressure liquid chromatography. All the above data are consistent with this enzyme catalyzing both phosphohydrolase and phosphotransferase reactions with the mediation of phosphohistidine in the reaction scheme(s).

Adenosine Triphosphate↗

Integration of hepatitis B virus DNA: evidence for integration in the single-stranded gap.

The DNA of hepatitis B virus (HBV) can integrate into the genomes of infected human liver cells and may be related to the development of primary liver carcinoma (PLC). This report describes the analysis of three integrated HBV DNA sequences cloned from DNA of the human PLC cell line PLC/PRF/5. In all these sequences, integration of the viral DNA is at a site that is single-stranded (gap) in the unintegrated HBV DNA. Contrary to some speculations, there are no large terminal redundancies flanking the inserts as found in retroviral proviruses. The viral sequences show no obvious rearrangements in these clones, but integration can be associated with deletions in the viral DNA and also apparently in the host DNA.

Base Sequence↗

Urethral mucosal sensitivity testing--a standardized contact medium.

A standardized contact medium for urethral mucosal sensitivity testing is described. The effects of temperature, pulse width and composition of the urethral contact medium on the electrical characteristics of the system and the effect of changing composition of the medium on its lubricant properties are discussed. It is recommended that a 50:50 volume for volume mixture of KY jelly and normal saline be adopted as a standard in order to facilitate the comparison of results between groups working in this field.

Electric Conductivity↗

Effect of opiate analgesia and opioid blockade on urethral mucosal sensitivity threshold.

The effect of opiate analgesics (omnopon, pethidine, pentazocine) on the urethral mucosal sensitivity threshold in 37 patients, and of the potent opiate/opioid antagonist naloxone on 10 volunteers is described. Omnopon and pentazocine caused a significant decrease in sensitivity (p less than 0.02) and naloxone caused a significant increase in sensitivity (p less than 0.02). The results confirm a role for the endogenous opioids in modulating urethral sensitivity, and the implications of this are discussed.

Analgesics, Opioid↗

The end of the road: residential disposals in the Scottish children's hearings system.

In a study of a representative sample of 301 "children's hearings", particular attention was given to 27 cases in which the child was committed to a List D school. Because the Scottish juvenile justice system has an explicit commitment to promoting the welfare of the children with whom it deals, the decisions were examined with special reference to the objectives that the hearing members hoped to achieve. These decisions could be divided into: (1) those which reflected only a sense that all alternatives had been exhausted; (2) those which aimed to ensure that the child received formal education or was placed in an environment which would help resolve his personal difficulties; (3) those designed to protect the child from family stresses or to achieve some other specific purpose. Since decisions under (1) are incompatible with the formal philosophy of the system, most of those under (2) entail no knowledge of the effectiveness of List D schools for the purposes in question, and some of those under (3) were wholly misconceived, it is concluded that there are some significant inconsistencies between the system's ideology and the actual practice of its members.

Adolescent↗

Structure of the hepatitis B virus genome.

The extent and position of the single-stranded gap in DNA molecules from Dane particles isolated from two donors of the adw serotype were determined by molecular hybridization and electron microscopic methods. The results showed that in each preparation more than 99% of the circular molecules are of uniform length and contain both single- and double-stranded regions. They confirmed that one end of the short strand is fixed with respect to the single EcoRI site within the molecule and to the nick in the long strand, but they also showed that although the position of the other end is variable, there is a preferred minimum length of about 650 to 700 nucleotides for the single-stranded region.

DNA, Viral↗

The role of "children's hearings" in child abuse and neglect.

The juvenile justice system established in Scotland in 1971, in which lay volunteers play a central part, provides a framework for making decisions about children in need of care and protection as well as those who have committed delinquent acts. Although cases of child abuse and neglect have come increasingly to the attention of children's hearings in recent years, they nevertheless constitute a small fraction of a workload dominated by cases of delinquency and truancy. A recent Scotland-wide study of the hearings system therefore gave only limited attention to the processing of abuse and neglect referrals. As a step towards rectifying this imbalance, a separate enquiry was carried out in 1981, when 43 such hearings were systematically observed and the participating panel members interviewed. Examination of these results indicates a heavy dependence on social workers' recommendations, a reluctance to open up sensitive areas for discussion, even though these may be of central importance, and an apparent lack of curiosity about the arrangements made for children removed from their homes, and the implications of these. In general, it is concluded that the anxiety generated by child abuse and neglect has prevented panel members from recognizing the distinctive features of their role in the decision-making process and has led them to fall back on an inappropriate model of practice derived from delinquency hearings. An alternative model is outlined.

Child↗

Hepatitis B virus core antigen: synthesis in Escherichia coli and application in diagnosis.

Fragments of hepatitis B virus DNA cloned in plasmid pBR322 carrying the gene for the viral core antigen have been placed under the control of the lac promoter of Escherichia coli. Several of the new recombinants direct higher levels of synthesis of the antigen, but the degree of enhancement varies with the different structures of the plasmids and hence the mRNAs produced. The antigen in crude bacterial lysates is a satisfactory diagnostic reagent for antibodies to the core antigen in serum samples.

Antibodies, Viral↗

CSF infections complicating the management of neoplastic meningitis. Clinical features and results of therapy.

This study analyzes the clinical and bacteriologic features of CSF infections that occurred in patients with neoplastic meningitis treated with thiotepa and methotrexate administered through a subcutaneous reservoir and ventricular catheter (SRVC). Thirty-one patients were treated, and CSF infections occurred in four (13%). Staphylococcus epidermidis was the infecting organism in each case and Pseudomonas maltophilia occurred with S epidermidis in one patient. Fever, headache, lethargy, and evidence of CSF extravasation around the SRVC were the common manifestations of infection. The CSF leukocytosis was the only laboratory abnormality noted. All infections were cured with the appropriate antibiotics and removal of the SRVC. Risk of CSF infection did not seem to be related to the use of high doses of dexamethasone, cranial radiation therapy, or the presence or absence of leukopenia. The SRVCs were replaced and treatment of neoplastic meningitis was resumed in three patients; infection did not recur. A CSF infection during management of neoplastic meningitis may be treated effectively and does not preclude adequate therapy of neoplastic meningitis.

Adult↗

Treatment of neoplastic meningitis with intraventricular thiotepa and methotrexate.

Twenty-five patients with involvement of the meninges by disseminated cancers were treated weekly with intraventricular thiotepa (10 mg) and methotrexate (10 mg) and with radiation therapy. Twenty-two of the 25 patients were clinically improved or stable. Malignant cells were cleared from the cerebrospinal fluid in 76% of the patients. Myelosuppression was the dose-limiting toxic effect, and neurotoxicity occurred in three patients. Combination chemotherapy employing thiotepa and methotrexate is a safe and effective treatment for neoplastic meningitis.

Adult↗

Transcription of sea urchin histone genes in Escherichia coli.

DNA fragments comprising units of the repeated histone genes form the sea urchins Psammechinus miliaris and Echinus esculentus were placed under the control of bacteriophage Lambda promoters by cloning into lambda replacement vectors. Although promoter-like regions exist within the cloned fragments, transcription of the histone genes is controlled mainly, but not exclusively, by lambda PL promoter. A transcription map of the cloned P. miliaris histone DNA fragment was obtained. The order of histone genes in E. esculentus was deduced from electron microscopic analyses of heteroduplexes with P. miliaris histone genes, and is similar to that in P. miliaris. Translation products of the transcripts have not been found in E. coli.

Animals↗

The conversion of hepatitis B core antigen synthesized in E coli into e antigen.

The antigen (HBeAg) of hepatitis B virus (HBV) is a polypeptide of 17-20,000 daltons closely associated with the core antigen (HBcAg) of Dane particles, from which it is released by a variety of disruptive procedures. HBeAg could be a unique component of HBV core particles or a derivative of HBcAg. To resolve this question immunodiffusion experiments were carried out with preparations of HBcAg synthesized in E coli carrying a recombinant plasmid from which the HBcAg, but no other HBV gene, was expressed. HBcAg was converted into HBeAg by proteolytic degradation under dissociating conditions, thus confirming at the molecular level that HBeAg is a component of HBcAg. This offers a new route to the detection of HBeAg and antibodies to the antigen.

Cloning, Molecular↗

Production of immunologically active surface antigens of hepatitis B virus by Escherichia coli.

Several plasmids have been constructed which direct the synthesis of hepatitis B virus surface antigens in Escherichia coli either as the native polypeptide or fused to other plasmid encoded polypeptides. When injected into rabbits, extracts from bacteria carrying some of these plasmids induced the synthesis of antibodies to the antigens even though the extracts did not give satisfactory positive results in radioimmunoassay for them. Either the NH2-terminal segment or the COOH-terminal segment of the surface antigens alone was sufficient to elicit the immune response, but antibodies against the two segments showed different specificities. The results emphasize the value of an in vivo assay for the presence of antigens in crude cell extracts and illustrate the feasibility of this type of screening with laboratory animals.

Antibody Specificity↗