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M O'Shea

Publications and source records attributed to M O'Shea.

At least 55 records · Page 3Linked to original sources
PubMed1992

Site-directed mutations that alter the inhibitory activity of the tissue inhibitor of metalloproteinases-1: importance of the N-terminal region between cysteine 3 and cysteine 13.

The tissue inhibitor of metalloproteinases-1 (TIMP-1) was subjected to single-site mutations within the N-terminal three loops using an oligonucleotide-directed polymerase chain reaction method. All the histidines, and a number of other residues conserved between TIMP-1 and TIMP-2, were individually modified and the mutant TIMPs expressed in mammalian cells. Purified mutant TIMPs were shown to be correctly folded by measuring the effect of guanidine hydrochloride on intrinsic fluorescence. Kinetic analyses of mutants using a quenched fluorescent peptide substrate and the metalloproteinase PUMP indicated that mutation of His7 and Gln9 caused an increase in the apparent dissociation constant, largely due to an increase in the rate of dissociation of complexes. The data indicate that the anchored sequence between Cys 3 and Cys 13 is a key region for interaction of TIMP-1 with metalloproteinases.

Amino Acid Sequence↗
PubMed1992

Adipokinetic hormones: cell and molecular biology.

Adipokinetic hormones AKH I (pGlu-Leu-Asn-Phe-Thr-Pro-Asn-Trp-Gly-Thr-NH2) and AKH II (pGlu-Leu-Asn-Phe-Ser-Trp-Gly-Thr-NH2) are synthesized by neurosecretory cells (NSC) of the corpora cardiaca (CC) in the locust, Schistocerca gregaria. These NSC constitute a homogeneous 'peptide factory' as each cell synthesizes both AKH I and AKH II. This homogeneity makes the CC an excellent system in which to study aspects of neuropeptide biosynthesis. This report summarizes recent findings on AKH inactivation and metabolism, as well as on AKH prohormone processing and biosynthesis.

Amino Acid Sequence↗
PubMed1992

Long-term outcome in fetal hydrops from parvovirus B19 infection.

Parvovirus B19 infection in the fetus is associated with anemia and hydrops and can result in fetal death. Fetal transfusion has been used in an attempt to improve outcome; however, it is associated with its own perinatal morbidity. We report two cases of fetal parvovirus B19 infection that were confirmed by polymerase chain reaction for parvovirus B19 deoxyribonucleic acid in umbilical cord blood. Ultrasonographic signs of compromise were observed at 30 and 24 weeks of gestation. Both fetuses were hydropic and one fetus was also anemic. Serial sonograms demonstrated that the hydrops resolved spontaneously over 3 to 5 weeks after diagnosis. One infant was delivered at 32 weeks of gestation as a result of idiopathic preterm labor. The other infant was delivered at term. Both infants appeared relatively normal at birth and have developed normally in the first year of life. Thus fetal hydrops in association with parvovirus B19 infection does not always lead to poor long-term outcome. A conservative approach without in utero therapy may be appropriate for the management of some of these fetuses.

Adult↗
PubMed1992

Prenatal events and the risk of subependymal/intraventricular haemorrhage in very low birthweight neonates.

The effects of prenatal factors on the risk of subependymal and/or intraventricular brain haemorrhage in very low birthweight (VLBW) neonates were studied. Data were collected on 201 consecutively born VLBW neonates without major congenital anomalies, who were born at a regional obstetric referral centre. Brain haemorrhage was identified by cranial ultrasound examinations. The reliability of these examinations (concordance among readers' interpretations) was assessed and found to be moderate (kappa = 0.47 for the finding of subependymal haemorrhage (SEH); kappa = 0.50 for the finding of intraventricular haemorrhage (IVH)). Prenatal factors were more strongly associated with IVH than with SEH. In univariable analyses, maternal pre-eclampsia, multiple gestation and maternal treatment with betamethasone were associated most strongly with a decreased risk of haemorrhage whereas labour and vaginal delivery were associated most strongly with an increased risk. These associations remained in a multivariable analysis which included prenatal events (maternal illnesses, fetal presentation and obstetrical interventions), as well as gestational age, birthweight, gender, treatment with assisted ventilation, and the occurrence of pneumothorax. Further aetiological study of the effects of prenatal factors could provide information useful in preventing SEH/IVH.

Cerebral Hemorrhage↗
PubMed1991

The N-terminal domain of tissue inhibitor of metalloproteinases retains metalloproteinase inhibitory activity.

Recombinant tissue inhibitor of metalloproteinases (TIMP-1) and a truncated version containing only the three N-terminal loops, delta 127-184TIMP, have been expressed in myeloma cells and purified by affinity chromatography and gel filtration. delta 127-184TIMP was found to exist as two main glycosylation variants of molecular mass 24 kD and 19.5 kDa and an unglycosylated form of 13 kDa. All forms of the truncated inhibitor were able to inhibit and form complexes with active forms of the matrix metalloproteinases, indicating that the major structural features for specific interaction with these enzymes resides in these three loops. Stable binding of delta 127-184TIMP to pro 95-kDa gelatinase was not demonstrable under the conditions for binding of full-length TIMP-1.

Amino Acid Sequence↗
PubMed1991

Regulation of neuropeptide stoichiometry in neurosecretory cells.

Peptidergic neurons and neurosecretory cells often contain multiple peptides, where they may be present in characteristic ratios. In this article, we describe how a set of five colocalized and coreleased peptides, two adipokinetic hormones (AKH I and AKH II), and three dimeric peptides (APRP 1, 2, and 3) are synthesized by the neurosecretory cells of the corpora cardiaca of the locust Schistocerca gregaria. We show that the five peptides are produced from two prohormones called pro-AKH I, or A-chain, and pro-AKH II, or B-chain. The amino acid sequences as determined by direct protein sequencing are given for both. Prior to processing, the two prohormones form the three possible dimers by the oxidation of the single cysteine residues found in each. The dimers, not the prohormones, are the direct precursors of the peptides. The dimeric precursors are called P1 (A-A), P2 (A-B), and P3 (B-B). Processing results in the generation of the two AKH peptides and the three dimers called adipokinetic hormone precursor-related peptides, or APRPs. Throughout postembryonic development, we show that the ratios of the AKHs and APRPs change dramatically and systematically. We show that these changes can be explained by the differential regulation of the synthesis of the two prohormones and their random association into dimers that are then completely processed. Regulation of peptide stoichiometry may expand the potential information content of the signals generated by multipeptide-producing neurons.

Aging↗
PubMed1990

Cytomegalovirus infection in a neonatal intensive care unit. Subsequent morbidity and mortality of seropositive infants.

In a study of blood transfusion and cytomegalovirus (CMV) infection in 385 infants, 5 (8%) of 60 seropositive infants with birthweights less than or equal to 1250 g acquired CMV. Four infants had become seronegative by the time of viral excretion and demonstrated significant morbidity with one death. Morbidity included variant (atypical) lymphocytosis, thrombocytopenia, Staphylococcal epidermidis and Candida parapsilosis infections, and respiratory deterioration. Interestingly, the infant who exhibited only minimal morbidity was seropositive at the time of viral excretion. CMV seropositivity at birth may not protect low birthweight (LBW) infants from the morbidity and mortality associated with CMV infection.

Antibodies, Viral↗
PubMed1989

Dimer structure of a neuropeptide precursor established: consequences for processing.

A prohormone (P1) of locust adipokinetic hormone I (AKH I) is shown here to be a homodimer of a 41 residue subunit called the A-chain. The A-chain, from the N terminal, consists of AKH I (10 amino acids starting with pyroglutamate) followed by a Gly-Lys-Arg processing site and then a 28 residues called the alpha chain containing a single cysteine and a potential Arg-Lys processing site. When processed each molecule of the homodimer precursor yields two copies of AKH I and one alpha chain homodimer. We call the alpha-alpha homodimer product of P1 processing AKH precursor related peptide 1 or APRP 1. The Arg-Lys dibasic pair found within the alpha chain is not cleaved in vivo. Our results show that neuropeptide precursors can be dimers and that dimer products can be synthesized by processing of a preformed dimer precursor rather than by dimerization of independent subunits.

Amino Acid Sequence↗
PubMed1989

Synthesis of a homodimer neurohormone precursor of locust adipokinetic hormone studied by in vitro translation and cDNA cloning.

The homodimer neurohormone precursor P1, consisting of 41 residue subunits or A-chains, is synthesized by the glandular neurosecretory cells of the corpora cardiaca (CC) of the locust Schistocerca gregaria. Processing of P1 generates two copies of a 10 amino acid peptide neurohormone (AKH I) and one copy of a homodimer peptide (APRP 1). Here we show that the P1 dimer is formed from two independent A-chain translation products. Translation of CC mRNA in vitro produces a prominent 6.4 kd protein, the synthesis of which can be blocked by oligonucleotides hybridizing to mRNA encoding the A-chain. Northern blot experiments suggest that the 6.4 kd protein is produced by an integral of 500 base mRNA. cDNA cloning reveals a pre-A-chain structure in which a single copy of the A-chain is preceded by a 22 amino acid signal peptide. This evidence indicates that the P1 dimer is synthesized by coupling of very small translational products rather than by folding and processing of a larger protein containing more than one copy of the A-chain.

Amino Acid Sequence↗
PubMed1989

Biosynthesis of adipokinetic hormones (AKHs): further characterization of precursors and identification of novel products of processing.

Two adipokinetic hormones (AKH I: pGlu-Leu-Asn-Phe-Thr-Pro-Asn-Trp-Gly-Thr-NH2, and AKH II: pGlu-Leu-Asn-Phe-Ser-Thr-Gly-Trp-NH2) are synthesized by the neurosecretory cells of the corpora cardiaca (CC) of the locust Schistocerca gregaria. Both AKHs are released into the blood during flight and serve to regulate lipid metabolism and other physiological processes involved in flight. By in vitro "pulse-chase" experiments we show that 2 precursors (P1 and P2) are involved in AKH biosynthesis. These are about 8.4 kDa polypeptides which are AKH immunoreactive but also contain an amino acid (tyrosine) not present in the AKH peptides. By following the fate of 14C-tyrosine incorporated into P1 and P2, we have identified 2 novel products of precursor processing. These are called AKH-Precursor Related Peptides or APRP 1 and APRP 2. Size exclusion chromatography shows that the APRPs are about 6.5 kDa large and therefore represent major fragments of the precursors. The optical density peaks corresponding to P1, P2, APRP 1, and APRP 2 on a reverse-phase chromatogram are identified. The precursors being metabolic intermediates are represented by minor optical density peaks that disappear when de novo protein synthesis is blocked by cycloheximide. In contrast, the APRPs are represented by major optical density peaks consistent with their being accumulating end products of AKH precursor processing. The function of the APRPs is as yet unknown. They are, however, co-synthesized and also co-released with the AKHs, and may therefore also have hormonal functions related to flight.

Animals↗
PubMed1988

Cytomegalovirus infection in a neonatal intensive care unit. Blood transfusion practices and incidence of infection.

We studied blood transfusion variables and cytomegalovirus (CMV) infection in 385 infants admitted to the Duke University Medical Center, Durham, NC, neonatal intensive care unit over 14 months. Cytomegalovirus antibody titers were measured at birth and monthly thereafter. Urine cultures for CMV were performed regularly. Infants admitted in the first six months (n = 197) received conventionally prepared blood. Infants admitted in the remaining eight months (n = 188) were given frozen, deglycerolized blood. Of the 105 infants weighing 1250 g or less (low birth weight [LBW]), 90 (86%) received transfusions. Two hundred eighty infants weighed more than 1250 g (non-LBW), and 111 (40%) of these were given blood. In the first six months of the study, three infants had CMV viruria. One case was congenital; two were acquired. Both infants who acquired infection were antibody-positive at birth and received multiple transfusions. In the remaining eight months, five infants had CMV viruria. Two cases were congenital; three were acquired. The three infants who acquired infection were antibody-positive at birth and received multiple transfusions. Our study demonstrates that infants with an LBW are more likely to receive blood transfusion and to be given significantly more blood than non-LBW infants. There was no difference in the number of infants acquiring CMV in the two periods despite the use of different preparations of blood.

Antibodies, Viral↗