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Biomedical subjects

P McIntyre

Publications and source records attributed to P McIntyre.

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

Mutagenesis of the regulatory domain of rat protein kinase C-eta. A molecular basis for restricted histone kinase activity.

Protein kinase C-theta (PKC-eta) is a member of the protein kinase C family that is characterized by Ca2+ independence and restricted histone kinase activity (Dekker, L. V., Parker, P. J., and McIntyre, P. (1992) FEBS Lett. 312, 195-199). Here we have investigated the molecular basis of this low histone kinase activity by limited proteolysis and site-directed mutagenesis. It is shown that a 46-kDa C-terminal tryptic fragment, representing the catalytic domain of PKC-eta, can phosphorylate histone. The Km value for histone of this catalytic fragment is 25-fold lower than that of intact PKC-eta. Thus, sites in the N-terminal regulatory domain upstream of the trypsin cleavage site (near residue 320) restrict histone kinase activity of intact PKC-eta. Deletion of the "Vo domain" (residues 2-137) generates a PKC-eta mutant that shows the same cofactor dependence and substrate phosphorylation as wild-type PKC-eta, indicating that the relevant sites do not appear to lie in the Vo domain but between amino acid 137 and the start of the catalytic domain. Deletion of the pseudosubstrate region (residue 155-171) generates a cofactor-independent kinase that has high histone kinase activity. A pseudosubstrate site point mutation in which the alanine residue at position 161 is replaced with a glutamic acid residue shows the same properties as the pseudosubstrate site deletion mutant. Km values for histone for both mutants are similar to that observed for the catalytic fragment. Therefore, in addition to its role in conferring cofactor dependence, the pseudosubstrate site also mediates the low histone kinase activity of wild-type PKC-eta. The data are discussed in the light of current models for PKC activation.

Amino Acid Sequence↗
PubMed1993

Altered substrate selectivity of PKC-eta pseudosubstrate site mutants.

Three protein kinase C (PKC)-eta mutants were constructed in which the whole or part of the pseudosubstrate site was replaced with corresponding parts of the PKC-alpha pseudosubstrate site. The resulting chimaeric kinases were compared with wild-type PKC-eta in their ability to phosphorylate a PKC-eta peptide substrate or histone. Changes in the pseudosubstrate site of PKC-eta are accompanied by changes in substrate selectivity, indicating that the substrate selectivity observed for PKC-eta is at least in part due to its pseudosubstrate site.

Amino Acid Sequence↗
PubMed1993

Invasive Haemophilus influenzae type b disease.

In this overview, the characteristics of Haemophilus influenzae type b (Hib) as an organism and the important clinical and diagnostic features of the diseases it causes are discussed. Important developments in vaccination and in the treatment and prevention of Hib disease are outlined.

Anti-Bacterial Agents↗
PubMed1993

Cloned murine bradykinin receptor exhibits a mixed B1 and B2 pharmacological selectivity.

We have isolated DNA clones encoding functional bradykinin receptors from human, rat, and mouse sources. Genomic bradykinin receptor clones have been isolated from mouse and human cosmid libraries and cDNA clones have been isolated from the human lung fibroblast cell line W138, from the neuroblastoma/glioma hybrid NG108-15, and from rat dorsal root ganglion cells. The receptor protein is encoded by an intronless region of the gene in both mouse and human. There is evidence of a splice acceptor site 8 bases upstream from the initiation codon in all three species. The function of the expressed receptor proteins from mouse, rat, and human was tested by electrophysiological assays after injection of cRNA into Xenopus laevis oocytes and also by binding assays with membranes from COS-7 cells transfected with cloned receptor-encoding DNA. The receptors from human and rat showed the pharmacological properties of B2 receptors in both expression systems when tested with a variety of bradykinin analogues, but receptors from mouse divided into two populations, one population with pharmacological properties of B1-like receptors and another, larger, population with properties of B2 receptors.

Amino Acid Sequence↗
PubMed1992

Biochemical properties of rat protein kinase C-eta expressed in COS cells.

Using a PKC-epsilon cDNA probe a cDNA for PKC-eta has been cloned from a rat lung cDNA library. When expressed in COS cells, rat PKC-eta appeared as an 84 kDa protein. PKC-eta expressed in COS cells, was solubilized by 1% Triton X-100 and purified away from the endogenous PKC-alpha by ammonium sulphate fractionation. The activity of this PKC-eta preparation was characterized with respect to cofactor dependence and substrate specificity. Various PKC pseudosubstrate peptides are phosphorylated by PKC-eta in a phospholipid and TPA-dependent but calcium-independent manner. The polypeptide histone IIIS is a poor substrate.

Amino Acid Sequence↗
PubMed1992

The cDNA cloning and immunological characterization of hamster p53.

We have cloned and sequenced the p53-encoding cDNA of Syrian hamster. The encoded product is 78% and 75% homologous to human and mouse p53, respectively. Immunoprecipitations of the cDNA-encoded protein by monoclonal antibodies specific for mammalian p53 confirmed the identity of the protein.

Amino Acid Sequence↗
PubMed1992

Induction of gene amplification by 5-aza-2'-deoxycytidine.

Treatment of Syrian hamster kidney cells with the demethylating agent 5-aza-2'-deoxycytidine (azadC) increased both the frequency and the rate of gene amplification appreciably. AzadC caused substantial DNA demethylation, which is likely to be responsible. The magnitude of the increases depended on the concentrations of both azadC and the drug used for selection. A transient stress response is not responsible since the increases were not dependent on cytotoxicity and were still apparent after several weeks. We discuss mechanisms by which azadC treatment may induce amplification by rendering DNA more prone to this process or by increasing the transcription of genes whose protein products stimulate amplification.

Animals↗
PubMed1992

Bone and joint infections caused by multiply resistant Staphylococcus aureus in a neonatal intensive care unit.

Twenty cases of osteomyelitis and/or septic arthritis caused by multiply resistant Staphylococcus aureus were documented in an Australian tertiary neonatal unit between 1981 and 1987. Eighteen (90%) occurred in the 3 years 1985 to 1987, an incidence of 9.6/1000 admissions in that period. All osteomyelitis and/or septic arthritis occurred in sick premature infants requiring intensive support. Eleven (55%) had a birth weight of less than 1500 g. An intravascular device was the most common portal of entry (14 of 20, 70%). Systemic symptoms were prominent at presentation, with local signs developing later in 18 (90%), usually within a week. Radiologic changes were almost always present by 10 days; radionuclide bone scanning was insensitive and did not hasten diagnosis. Osteomyelitis was multifocal in 11 cases (55%), with the long bones, particularly of the upper limb, most commonly affected. Large joint involvement was uncommon (15%). Intravenous vancomycin for a mean of 32 days was associated with low mortality (1 of 20) and toxicity; surgical drainage was not performed. Follow-up at a minimum of 4 months (mean, 25.5 months) showed residual signs in the affected limb in 30%, none with significantly impaired function. Skeletal infection should be searched for rigorously in neonatal multiply resistant S. aureus sepsis. In the absence of large joint disease, vancomycin therapy alone for a minimum of 3 weeks gives good short term results with minimal toxicity.

Arthritis, Infectious↗
PubMed1992

Expression of functional bradykinin receptors in Xenopus oocytes.

mRNA prepared from various tissues and cultured cells was injected into Xenopus laevis oocytes. Three to five days after injection, the response of the oocytes to the peptide bradykinin was monitored. The oocytes were voltage clamped and the membrane currents generated on application of agonist were recorded. mRNA from NG108-15, rat uterus, and human fibroblast cell line WI38 gave similar responses to bradykinin (1 microM), with an initial inward current (10-20 nA) followed by a prolonged period of membrane current oscillations. The same pattern of response was given by total RNA from rat dorsal root ganglia. No response to bradykinin (10 microM) was recorded from oocytes injected with rat brain mRNA, although these oocytes gave peak inward currents of about 75 nA in response to serotonin (10 microM). mRNA from both NG108-15 cells and rat uterus was fractionated on sucrose gradients. This resulted in an approximately five-fold increase in the size of the response compared to that given by unfractionated mRNA. The largest responses were given by mRNA fractions with a size of approximately 4.5 kb. Data were obtained consistent with the expression of both B1 and B2 receptors by WI38 human fibroblasts and with the expression of only the B2 type of receptor by NG108-15 cells.

Animals↗
PubMed1991

Five cases of neurocysticercosis diagnosed in Sydney.

Cysticercosis, once rare in Australia, is now more frequently diagnosed. This change reflects the countries of origin of new immigrants and the destinations of Australians travelling. Five cases of neurocysticercosis diagnosed at Westmead Hospital in Sydney are described. Two involved Australians, a father and son who had visited eastern and southeastern Asia 10 years before presentation. The other three included immigrants from Chile and India and a visitor from Timor. Ages ranged from 5 to 57 years. Three individuals presented after focal seizures involving the upper limb, one had a long standing history of neurological dysfunction and one suffered from persistent headaches. In all cases computed tomographic scanning (CT) or magnetic resonance imaging (MRI) revealed cystic brain lesions and three of the five were seropositive as well. Four were treated with praziquantel and in one the lesions regressed significantly following treatment. However, the lesion in one case had decreased in size prior to treatment and that in the untreated individual also became smaller.

Adult↗
PubMed1990

Psychological and psychophysiological characteristics in irritable bowel syndrome.

Psychiatric disorder is reported to occur in a large proportion of patients with irritable bowel syndrome (IBS) and psychological treatment methods have been advocated for this patient group. In a sample of 25 out-patients with intractable IBS, only four patients with psychiatric disorder were identified. The majority did not have elevated levels of anxiety or depression nor was there evidence of significant abnormal illness behaviour. Electrodermal activity did not show the extremes of responding and habituation associated with anxiety, depression or chronic pain. It is suggested that, when accurate diagnostic criteria are employed, a specific relationship between IBS and psychopathology is no longer evident.

Adult↗
PubMed1990

DNA hybridisation of routinely processed tissue for detecting HPV DNA in anal squamous cell carcinomas over 40 years.

To study possible changes in the incidence of human papillomavirus (HPV) associated anal squamous cell carcinomas (SCC) a simple, rapid, and sensitive technique (alkaline hydrolysis) to permit DNA hybridisation from formalin fixed, paraffin wax embedded tissue was developed. The sensitivity and specificity of the technique were established by comparison with Southern blot analysis and in situ hybridisation on the same tissue specimens. Ninety tissue specimens in a single analysis were examined using this technique. Alkaline hydrolysis was applied to fixed tissue samples which showed a two-fold increase over the past 10 years in the percentage of anal cancers containing HPV type 16 DNA when compared with the previous 30 years using 207 cases of anal cancer collected over a 40 year period. This method has several advantages over the polymerase chain reaction as it is simple, relatively inexpensive, and may be widely applied to the detection and quantification of DNA sequences, including cellular oncogenes.

Anus Neoplasms↗
PubMed1988

Late-onset neonatal sepsis due to multiply-resistant coagulase-negative staphylococci.

A cluster of septic episodes that were caused by coagulase-negative staphylococci occurred in eight patients, over a six-month period from August 1, 1984 to January 31, 1985, in a Brisbane neonatal intensive-care unit where sepsis which was due to these organisms previously was uncommon. The organisms were universally-resistant to tobramycin (the aminoglycoside agent that was used at that time) and were variably-resistant to gentamicin, flucloxacillin and cephalothin. All organisms were sensitive to netilmicin, vancomycin, fusidic acid and rifampicin. The affected infants were all of 32 weeks' or less gestation and most of them weighed less than 1500 g at birth. All neonates had been ventilated artificially and had had long intravascular lines. Two infants had ventriculoperitoneal shunts that had been infected with coagulase-negative staphylococci--a potentially-important problem that has not been noted in premature infants in previous reports. Our experience demonstrates that it is important to consider the patterns of resistance to aminoglycoside as well as to beta-lactam antibiotic agents for the empirical therapy of septic episodes and for neurosurgical prophylaxis in nurseries where coagulase-negative staphylococci are emerging as common nosocomial pathogens.

Anti-Bacterial Agents↗
PubMed1988

Variation in the precursor to the major merozoite surface antigens of Plasmodium falciparum.

The major antigens on the surface of Plasmodium falciparum merozoites are derived from a single high molecular weight polypeptide. The precursor to the major merozoite surface antigen (PMMSA) has conserved and variable antigenic determinants and varies in size in different isolates. Since the protein is a candidate for a malaria vaccine, it is important to understand the molecular basis of this variation. We present the complete sequence of the PMMSA of the Papua New Guinea isolate FC27 and the partial sequence of the West African isolate NF7. The gene consists of blocks of sequence which are either conserved or variable between different isolates. Variable sequences fall into two distinct types, indicating that the PMMSA is encoded by dimorphic alleles that undergo recombination within conserved blocks at the 5' end of the gene. Genetic exchange is not apparent within the other two-thirds of the gene in 12 isolates, suggesting strong selection against such recombinants. The most variable block located near the 5' end contains repeats that are different in independent cloned isolates. This variation presumably accounts for much of the size and antigenic variability.

Alleles↗