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J O'Brien

Publications and source records attributed to J O'Brien.

At least 109 records · Page 6Linked to original sources
PubMed1999

A contiguous 3-Mb sequence-ready map in the S3-MX region on 21q22.2 based on high- throughput nonisotopic library screenings.

Progress in complete genomic sequencing of human chromosome 21 relies on the construction of high-quality bacterial clone maps spanning large chromosomal regions. To achieve this goal, we have applied a strategy based on nonradioactive hybridizations to contig building. A contiguous sequence-ready map was constructed in the Down syndrome congenital heart disease (DS-CHD) region in 21q22.2, as a framework for large-scale genomic sequencing and positional candidate gene approach. Contig assembly was performed essentially by high throughput nonisotopic screenings of genomic libraries, prior to clone validation by (1) restriction digest fingerprinting, (2) STS analysis, (3) Southern hybridizations, and (4) FISH analysis. The contig contains a total of 50 STSs, of which 13 were newly isolated. A minimum tiling path (MTP) was subsequently defined that consists of 20 PACs, 2 BACs, and 5 cosmids covering 3 Mb between D21S3 and MX1. Gene distribution in the region includes 9 known genes (c21-LRP, WRB, SH3BGR, HMG14, PCP4, DSCAM, MX2, MX1, and TMPRSS2) and 14 new additional gene signatures consisting of cDNA selection products and ESTs. Forthcoming genomic sequence information will unravel the structural organization of potential candidate genes involved in specific features of Down syndrome pathogenesis.

Chromosome Mapping↗
PubMed1999

Pharmacological properties of J-104132 (L-753,037), a potent, orally active, mixed ETA/ETB endothelin receptor antagonist.

J-104132 [(+)-(5S,6R, 7R)-2-butyl-7-[2-((2S)-2-carboxypropyl)-4-methoxyphenyl]-5-(3, 4-methylenedioxyphenyl)cyclopenteno[1,2-b]pyridine-6-carboxylic; also referred to as L-753,037] is a potent, selective inhibitor of ETA and ETB endothelin (ET) receptors (e.g., Ki: cloned human ETA = 0.034 nM; cloned human ETB = 0.104 nM). In both ligand-binding and isolated tissue preparation protocols, the inhibition of ET receptors with J-104132 is reversible and competitive. In vitro, J-104132 is a potent antagonist of ET-1-induced accumulation of [3H]inositol phosphates in Chinese hamster ovary cells stably expressing cloned human ETA receptors (IC50 = 0.059 nM), ET-1-induced contractions in rabbit iliac artery (pA2 = 9.70) and of BQ-3020-induced contractions in pulmonary artery (pA2 = 10.14). J-104132 is selective for ET receptors because it had no effect on contractions elicited by norepinephrine or KCl in the vascular preparations. The in vivo potency of J-104132 was assessed using challenges with exogenous ET-1. In conscious mice, 5 nmol/kg i.v. ET-1 causes death. Pretreatment with J-104132 prevents the lethal response to ET-1 when administered i.v. (ED50 = 0.045 mg/kg) or p.o. in fed animals (ED50 = 0.35 mg/kg). In conscious, normotensive rats, pressor responses to 0.5 nmol/kg i.v. ET-1 are inhibited by J-104132 after i.v. (0.1 mg/kg) or p.o. (1 mg/kg) administration. In anesthetized dogs, ET-1 was administered directly into the renal artery or brachial artery to generate dose-response (blood flow) curves, and the inhibitory potency of J-104132 (i.v. infusion) was quantified. J-104132 produced greater than 10-fold shifts in the ET-1 dose-response curves at 0.03 mg/kg/h (renal) and 0.3 mg/kg/h (brachial). Oral bioavailability of J-104132 in rats was approximately 40%. These studies indicate that J-104132 is a selective, potent, orally active antagonist of both ETA and ETB receptors and is an excellent pharmacological tool to explore the therapeutic use of a mixed ETA/ETB receptor antagonist.

Animals↗
PubMed1998

Severe deep white matter lesions and outcome in elderly patients with major depressive disorder: follow up study.

OBJECTIVE: To determine the difference in outcome among elderly people with major depression who do and do not have severe white matter lesions on magnetic resonance imaging. DESIGN: Follow up study. SETTING: Two psychiatric and two general hospitals in Melbourne, Australia. SUBJECTS: 60 depressed subjects aged over 55 referred to hospital psychiatric services with major depressive disorder meeting American Psychiatric Association (DSM-IIIR) criteria. MAIN OUTCOME MEASURE: Proportion with good outcome as determined by full recovery from initial illness and no evidence of depressive relapse or cognitive decline during follow up among those with and without lesions. RESULTS: Mean (SD) follow up was 31.9 (9.9) months. Survival analysis showed a significant effect of severe lesions on time to poor outcome (P=0.04), with median survival 136 days in those with severe lesions compared with 315 days in those without. CONCLUSION: Severe white matter change on magnetic resonance imaging is associated with poor outcome in elderly depressed subjects.

Aged↗
PubMed1998

Cloning and expression of two related connexins from the perch retina define a distinct subgroup of the connexin family.

We have cloned cDNAs for two closely related connexins (Cx), Cx35 and Cx34.7, from a perch retinal cDNA library. Sequencing of PCR products from genomic DNA revealed that both connexins have an intron 71 bp after the translation initiation site; in Cx35, the intron is 900 bp in length, whereas in Cx34.7 it is approximately 20 kb. Southern blots of genomic DNA suggest that the two connexins represent independent single copy genes. In Northern blots, Cx35 and Cx34.7 transcripts were detected in retina and brain; Cx34.7 also showed a weak signal in smooth muscle (gut) RNA. Antibodies against Cx35 labeled a 30 kDa band on a Western blot of retinal membranes, and in histological sections, the pattern of antibody recognition was consistent with labeling of bipolar cells and unidentified processes in the inner plexiform and nerve fiber layers. When expressed in Xenopus oocytes, Cx35 and Cx34.7 formed homotypic gap junctions, but the junctional conductance between paired oocytes expressing Cx35 was 10-fold greater than that recorded for gap junctional channels formed by Cx34.7. The homotypic gap-junctional channels were closed in a voltage-dependent manner but with relatively weak voltage sensitivity. Heterotypic gap junctions formed by Cx35 and Cx34.7 displayed junctional conductances similar to those of Cx34.7 homotypic pairs and showed a slightly asymmetric current-voltage relationship; the side expressing Cx35 exhibited a higher sensitivity to transjunctional potentials. An analysis of the sequence and gene structure of the connexin family revealed that perch Cx35 and Cx34.7, skate Cx35, and mouse Cx36 constitute a novel gamma subgroup.

Animals↗
PubMed1998

Pneumococcal vaccination in HIV-1-infected adults in Uganda: humoral response and two vaccine failures.

OBJECTIVES: To assess the feasibility of establishing a pneumococcal vaccine trial among HIV-1-infected adults in Uganda and to characterize their responses to 23-valent pneumococcal polysaccharide vaccine. DESIGN: An open-label pilot trial to assess recruitment and compliance of HIV-1-infected adults in Uganda to vaccination and to determine the immunogenicity of the vaccine. SETTING: A community clinic for HIV-1-infected adults in Entebbe, Uganda. METHODS: Levels of capsule-specific IgG to four common vaccine capsular serotypes were measured before vaccination and 1 month after vaccination. Subsequent rates of disease episodes and deaths, and immunologic responses in two vaccine failures, were followed. RESULTS: One month after-vaccination, both HIV-1-infected (n = 77) and seronegative control subjects (n = 10) demonstrated a significant rise in capsule-specific immunoglobulin G (IgG) for three of four serotypes tested, but levels were significantly lower among HIV-1-infected patients. In 149 patient-years of follow-up, two (2.6%) developed pneumococcal pneumonia, one bacteremic with serotype 1 and one non-bacteremic with serotype 13, a non-vaccine serotype; both patients showed inadequate killing of the organism in vitro. In this same follow-up period, 29 (38%) patients died. CONCLUSION: HIV-1-infected adults in Uganda are at high risk of pneumococcal disease and show a significant but suboptimal response to pneumococcal vaccine. Although reliable recruitment and follow-up of vaccinees is feasible, evaluation of vaccine efficacy may be compromised by limited responses to common vaccine serotypes, an unknown incidence of disease with non-vaccine serotypes, and a high rate of mortality unrelated to Streptococcus pneumoniae infection.

AIDS-Related Opportunistic Infections↗
PubMed1998

Rearrangement reactions in the biosynthesis of molybdopterin--an NMR study with multiply 13C/15N labelled precursors.

The genes moaABC of Escherichia coli were ligated into the expression vector pNCO113. The resulting plasmid was transformed into a moeA mutant of E. coli. From cultures of the recombinant strain, a pteridine designated compound Z could be isolated at 5 mg/liter. Compound Z is a product of precursor Z, a biosynthetic precursor of molybdopterin. Cultures of the recombinant E. coli strain were supplied with [U-(13)C6]glucose, [U-(13)C5]ribulose 5-phosphate, or [7-(15)N,8-(13)C]guanine. The culture medium also contained a large excess of unlabeled glucose. Compound Z as well as nucleosides obtained by hydrolysis of RNA were isolated from the bacterial cultures, and their heavy isotope distribution was investigated by one-dimensional and two-dimensional NMR spectroscopy. The labelling patterns of compound Z show that the carbon atoms of a pentose or pentulose are diverted to the ring atoms C6 and C7 and to the side chain atoms C2', C3' and C4' of compound Z. Carbon atom C1' of compound Z is derived from carbon atom C8 of a guanine derivative. The remodeling of the carbon skeleton of the pentose and purine moieties proceed via intramolecular rearrangement reactions.

Carbon Isotopes↗
PubMed1998

Isolation and characterization of a skate retinal GABA transporter cDNA.

PURPOSE: The inhibitory neurotransmitter gamma-aminobutyric acid (GABA) is believed to play a crucial role in the processing of information within the vertebrate retina. Extracellular concentrations of GABA are thought to be tightly regulated by carrier-mediated transport proteins in neurons and glial cells. The purpose of this work was to isolate the gene that encodes one of these transport proteins in the skate retina. METHODS: cDNA clones were isolated from a skate retinal cDNA library using a mouse retinal GABA transporter (GAT1) cDNA as a probe. The PCR technique was used to fill sequence gaps, and 5' and 3' RACE were employed to amplify the 5' and 3' untranslated regions. The amplified fragments were subcloned into a T-vector. Blots containing RNA from 10 different tissues were probed to determine the size of the transcript and the tissue distribution. RESULTS: Sequence analysis revealed that the skate retinal GABA transporter cDNA shared 72% identity with the mouse GABA transporter-1 at the DNA level and 80% identity at the amino acid level. Multiple sequence alignments showed that our sequence is closest to the Torpedo GABA transporter-1. Two transcripts, 4.5 and 7 kb, were detected in retina and possibly brain by RNA blot analysis. Fourteen introns were detected in the skate GABA transporter gene. CONCLUSIONS: We successfully isolated a full length GABA transporter cDNA from the retina of the skate. The size of the full length sequence of the skate retinal GABA transporter is in agreement with the size of the smaller transcript detected on RNA blots. The larger transcript observed on the RNA blot may be the result of either alternative splicing or utilization of a downstream poly A signal.

Animals↗
PubMed1998

Impaired IL-1beta-induced neutrophil accumulation in tachykinin NK1 receptor knockout mice.

Tachykinin NK1 receptors play an important role in the development of neurogenic inflammatory responses. We have used the murine air-pouch model to investigate whether the neurogenic component of the cellular inflammatory response to interleukin-1beta (IL-1beta, 10 ng into the air-pouch) is altered in NK1 receptor knockout mice compared to wild type controls. Air-pouches were washed following a 4 h IL-1beta treatment, the wash collected and neutrophil number estimated using a Neubauer haemocytometer. The response to IL-1beta was significantly attenuated in NK1 receptor +/- (40% reduction) and -/- mice (62% reduction) compared to wild type controls (+/+), whilst the response to cytokine-induced neutrophil chemoattractant (CINC, 0.3 microg) was unaffected. The response to substance P (7.5 nmol) was attenuated by approximately 50% in both NK1 receptor +/- and -/- mice compared to wild type controls. In conclusion NK1 receptors play a significant role in the cellular response to IL-1beta in a model of inflammation.

Animals↗
PubMed1998

A prospective study of dementia with Lewy bodies.

BACKGROUND: little is known about the longitudinal course of dementia with Lewy bodies (DLB) and how this differs from Alzheimer's disease (AD). METHOD: standardized baseline and annual assessments of cognitive and non-cognitive symptoms are reported in a cohort of 72 patients with DLB or AD. AD was diagnosed using the NINCDS ADRDA criteria and DLB was diagnosed with the criteria of McKeith et al. Cognitive assessment was undertaken using the MMSE schedule and operationalized definitions were used to diagnose non-cognitive symptoms. RESULTS: 42 patients with DLB and 30 patients with AD were assessed. Of the 19 on whom post mortem examinations have been performed, 18 (95%) have had the clinical diagnosis confirmed. DLB patients were significantly more likely to experience visual hallucinations, disturbances of consciousness and parkinsonism at both baseline and at annual assessments. Of DLB patients exposed to neuroleptics, 33% developed sensitivity reactions. The magnitude and pattern of cognitive decline was similar in both groups. CONCLUSION: the importance of the core features highlighted in the newly proposed consensus DLB criteria is supported. These features appear to be stable over time.

Aged↗
PubMed1998

Treatment of type-two odontoid fractures in halothoracic vests.

We treated 22 patients with type-two odontoid fractures in halothoracic vests for six to eight weeks followed by a Philadelphia collar for four weeks. Eighteen patients were reviewed by questionnaire and radiography at a mean of 40 months after injury. We assessed union, fracture position, the degree of permanent pain and stiffness, satisfaction with the treatment and the outcome. The overall union rate was 82%. Posterior malunion with residual posterior displacement or angulation was associated with a higher incidence of persisting pain. The position at union did not correlate with the residual cervical stiffness. Fractures failed to unite in four patients (18%) none of whom had late neurological sequelae, although they had more late pain. There were associations between the development of nonunion and an extension-type injury, age over 65 years and delay in diagnosis.

Adolescent↗
PubMed1998

Intraorbital squamous epithelial cyst: an unusual complication of Silastic implantation.

Thin Silastic sheet alloplasts (Dow Corning, Midland, MI, U.S.A) are commonly used to reconstruct posttraumatic orbital floor defects. Complications associated with orbital Silastic implantation include infection, migration, and extrusion. The authors report an unusual case of an intraorbital, squamous, epithelial-lined cyst appearing as progressive vertical globe dystopia and proptosis occurring after Silastic reconstruction of a traumatic orbital floor defect.

Bone Cysts↗
PubMed1997

Nerve ingrowth into diseased intervertebral disc in chronic back pain.

BACKGROUND: In the healthy back only the outer third of the annulus fibrosus of the intervertebral disc is innervated. Nerve ingrowth deeper into diseased intervertebral disc has been reported, but how common this feature is and whether it is associated with chronic pain are unknown. We examined nerve growth into the intervertebral disc in the pathogenesis of chronic low back pain. METHODS: We collected 46 samples of intervertebral discs from 38 patients during spinal fusion for chronic back pain. 30 samples were from pain levels clinically established by discography and 16 samples were from adjacent vertebral levels with no pain. We obtained 34 control samples of intervertebral disc from previously healthy individuals with normal histology within 8 h of recorded death. We used standard immunohistochemical techniques to test for a general nerve marker, a nociceptive neurotransmitter (substance P), and a protein expressed during axonogenesis (growth-associated protein 43 [GAP43]). FINDINGS: We identified nerve fibres in the outer third of the annulus fibrosus in 48 (60%) of the 80 samples of intervertebral discs. Nerves were restricted to the outer or middle third of the annulus fibrosus in the 34 control samples. Among the patients with chronic low back pain, nerves extended into the inner third of the annulus fibrosus and into the nucleus pulposus in 21 (46%) and ten (22%) samples, respectively. Nerves usually accompanied blood vessels, but in 14 of the samples from back-pain patients, isolated nerve fibres were seen in the discal matrix. Both types of nerve fibres expressed substance P, but only non-vessel-associated fibres expressed GAP43. Deep nerve ingrowth into the inner third of the annulus fibrosus, the nucleus pulposus, or both was seen in four (25%) of 16 biopsy samples from non-pain levels and in 17 (57%) samples from pain levels. Of the 16 paired samples from both pain and non-pain levels, five pain-level samples and one non-pain-level sample showed deep nerve ingrowth. INTERPRETATION: Our finding of isolated nerve fibres that express substance P deep within diseased intervertebral discs and their association with pain suggests an important role for nerve growth into the intervertebral disc in the pathogenesis of chronic low back pain.

Adult↗
PubMed1997

Molecular cloning of a rod opsin cDNA from the skate retina.

Skates (Raja erinacea and R. ocellata) are among the few animals that have an exclusively rod retina. However, skate rods are unusual in that they are capable of adapting to extremely high levels of illumination that initially saturate the rod photocurrent. This adaptive process restores the ability of the visual cells to respond to incremental photic stimuli and enables them to function under ambient conditions that are subserved by the cone mechanism in mixed (rod/cone) retinae. As a first step towards exploring the molecular basis of visual adaptation in the skate retina, we have cloned and analyzed the opsin cDNA from a skate retina library. The cDNA codes for a protein 354 amino acids (aa) long and 39.7 kDa predicted molecular mass, and labels a single abundant transcript of 1.7 kb in retinal RNA. Amino acid alignments and a parsimony analysis of nucleotide alignments show the skate opsin to be homologous to other rod opsins. An analysis of the aa sequence reveals a high degree of conservation of those residues thought to be important for most aspects of rhodopsin function. However, a few critical aa replacements may indicate alterations in the interactions of skate rhodopsin with other proteins in the phototransduction cascade. In particular, replacements of Glu150 with serine and Cys323 with leucine are in cytoplasmic domains thought to interact with transducin and rhodopsin kinase. The latter change eliminates one of the conserved acylation sites in the carboxyl terminal tail. These substitutions increase the similarity of the cytoplasmic domains of skate opsin to those of blue-sensitive visual pigments.

Amino Acid Sequence↗
PubMed1997

Leiomyosarcoma of the inferior vena cava: a clinicopathologic review and report of three cases.

BACKGROUND AND OBJECTIVES: We operated on three patients with leiomyosarcoma of the inferior vena cava. METHODS: Complete excision was possible in all three patients. RESULTS: One patient developed widespread metastasis at 23 months, one patient is alive with no evidence of disease at 70 months, and one patient is alive at 15 months. The third patient had subcutaneous and pulmonary metastases at the time of presentation, which are radiologically nondetectable at present following postoperative chemotherapy. CONCLUSIONS: The clinicopathologic features, prognostic factors, and treatment of 130 cases found in a comprehensive literature search and our three cases are reported.

Aged↗
PubMed1997

Surgical morbidity, mortality, and long-term survival in patients with peripancreatic cancer following pancreaticoduodenectomy.

BACKGROUND: Surgical resection of the primary tumor in peripancreatic cancer has been associated with an improved survival and decreased morbidity in the recent literature. The purpose of this review was to analyze the results at a single institution. METHODS: Between 1985 and 1995, 88 patients underwent a pancreaticoduodenectomy for adenocarcinoma of the pancreatic head region and had complete long-term follow-up. Patient records were reviewed to determine morbidity, mortality, and survival. RESULTS: Tumor histology included pancreatic head adenocarcinoma (n = 46), ampullary adenocarcinoma (n = 28), duodenal adenocarcinoma (n = 8), and cholangiocarcinoma (n = 6). Morbidity occurred in 26 patients (29%). Perioperative mortality was seen in 6 patients (7%). No perioperative mortality was seen over the last 3 years, which included 33 patients. The mean follow-up was 29 months, with a median survival of 19 months. At last follow-up, 24 patients were alive without disease with an average survival of 43 months (1 to 141). There were 54 patients who died with cancer with an average survival of 21 months (1 to 117). Based on Kaplan and Meier statistical analysis the estimated survival was 47% at 2 years and 25% at 5 years. The location of the primary tumor (P = 0.0006) and the presence of positive lymph nodes (P = 0.05) was shown to have a negative impact on survival. CONCLUSION: Pancreaticoduodenectomy can be done with acceptable morbidity and mortality. The outlook with this disease remains poor, but long-term survival can be achieved in some patients.

Adenocarcinoma↗
PubMed1997

Human thiopurine methyltransferase pharmacogenetics: gene sequence polymorphisms.

Thiopurine methyltransferase (TPMT) catalyzes the S-methylation of thiopurine drugs. TPMT activity is regulated by a common genetic polymorphism that is associated with large individual variations in thiopurine toxicity and efficacy. We previously cloned the functional gene for human TPMT and reported a common variant allele for low enzyme activity, TPMT*3A, that contains point mutations at cDNA nucleotides 460 and 719. In the present study, we set out to determine the number, types, and frequencies of TPMT variant alleles associated with low enzyme activity in clinical laboratory samples in the United States and to compare those results with data obtained from two different ethnic groups. We identified a total of six different variant alleles for low TPMT activity in the 283 clinical laboratory samples studied. The most common variant was *3A; the second most frequent variant allele, *3C, contained only the nucleotide 719 polymorphism; and four other variant alleles were detected. TPMT*3A also appeared to be the most common variant allele in a Norwegian white population sample, but it was not found in a population sample of Korean children. However, *3C was present in samples from the Korean children, as was novel allele, *6. Characterization of variant alleles for low TPMT enzyme activity will help make it possible to assess the potential clinical utility of deoxyribonucleic acid-based diagnostic tests for determining TPMT genotype.

Alleles↗
PubMed1997

A prospective study of psychotic symptoms in dementia sufferers: psychosis in dementia.

Eighty-seven out of a clinical cohort of 124 patients with Diagnostic and Statistical Manual of Mental Disorders (3rd ed., rev.) dementia were followed up at monthly intervals for 1 year. Psychotic symptoms were assessed using the Burns's Symptom Checklist, and cognitive functioning was evaluated with the CAMCOG. The annual incidence rate of psychotic symptoms was 47%, although many of the incident symptoms lasted less than 3 months. Fifty-three percent of patients with psychosis experienced resolution of their symptoms. Patients either experienced brief or persistent psychotic disorders, with few having an intermediary course. Persistent psychosis was significantly associated with a 3-month duration of symptoms at baseline. Neuroleptics did not significantly influence the course of psychotic symptoms.

Aged↗