Search PubMed⌕ Search

Biomedical subjects

M O'Connor

Publications and source records attributed to M O'Connor.

At least 163 records · Page 9Linked to original sources
PubMed1993

Mutations at U2555, a tRNA-protected base in 23S rRNA, affect translational fidelity.

A plasmid carrying a mutation in the highly conserved base U2555 in Escherichia coli 23S rRNA was isolated by selecting for suppression of the -1 frameshift mutation trpE91. U2555 is normally protected in chemical footprinting experiments by the aminoacyl residue of A-site-bound tRNA. Substitution of U2555 by adenine or guanine (but not by cytosine) increased readthrough of all three stop codons and +1 and -1 frameshifting. These effects on translational fidelity demonstrate the importance of U2555 for selection of the correct tRNA at the ribosomal A site.

Amino Acid Sequence↗
PubMed1993

Psychotherapy and bulimia nervosa. Longer-term effects of interpersonal psychotherapy, behavior therapy, and cognitive behavior therapy.

OBJECTIVE: To determine whether cognitive behavior therapy (CBT) for bulimia nervosa has a specific therapeutic effect and determine whether a simplified behavioral treatment (BT) of CBT is as effective as the full treatment. DESIGN: Randomized controlled trial involving three psychological treatments. Two planned comparisons, CBT with interpersonal psychotherapy (IPT), and CBT with BT. Closed 12-month follow-up period. Independent assessors. SETTING: Secondary referral center. PATIENTS: Seventy-five consecutively referred patients with bulimia nervosa. Patients with concurrent anorexia nervosa were excluded. INTERVENTIONS: Cognitive behavior therapy, IPT, BT conducted on an individual outpatient basis. There were nineteen sessions over 18 weeks. Six experienced therapists administered all three treatments. There was no concurrent treatment. MAIN OUTCOME MEASURE: Frequency of binge eating and purging. RESULTS: High rate (48%) of attrition and withdrawal among the patients who received BT. Over follow-up, few patients undergoing BT met criteria for a good outcome (cessation of all forms of binge eating and purging). Patients in the CBT and IPT treatments made equivalent, substantial, and lasting changes across all areas of symptoms, although there were clear temporal differences in the pattern of response, with IPT taking longer to achieve its effects. CONCLUSIONS: Bulimia nervosa may be treated successfully without focusing directly on the patient's eating habits and attitudes to shape and weight. Cognitive behavior therapy and IPT achieved equivalent effects through the operation of apparently different mediating mechanisms. A further comparison of CBT and IPT is warranted. The behavioral version of CBT was markedly less effective than the full treatment.

Adolescent↗
PubMed1993

Functional tRNAs with altered 3' ends.

The CCA trinucleotide is a universally conserved feature of the 3' end of tRNAs, where it serves as the site of amino acid attachment. Despite this extreme conservation, we have isolated functional mutants of tRNA(His) and tRNA(Val1) with altered CCA ends. A mutant that leads to de-repression of the histidine biosynthetic operon in Salmonella typhimurium has been characterized and found to have the CCA end of the sole tRNA(His) species mutated to UCA. However, constructed mutants of tRNA(His) with ACA or GCA ends appeared to be nonfunctional in vivo. Mutants of Escherichia coli tRNA(Val1) with GCA or ACA ends were isolated on the basis of their ability to promote frameshifting at a specific sequence. These same tRNA(Val1) mutants also caused read-through of stop codons that were one, or in some instances two, codons downstream of the valine codon decoded by the mutant tRNA. A startling implication of these data is that disruption of interactions between the CCA end of the tRNA and the large ribosomal subunit promotes these aberrant codon-anticodon interactions on the small ribosomal subunit.

Amino Acid Sequence↗
PubMed1993

Lipopolysaccharide-induced suppression of erythrocyte binding and phagocytosis via Fc gamma RI, Fc gamma RII, Fc gamma RIII, and CR3 receptors in murine macrophages.

In this study we have investigated the ability of lipopolysaccharide (LPS) to suppress binding and phagocytosis of erythrocytes via various receptors on mouse macrophages. Thioglycollate-elicited peritoneal macrophages were treated in vitro with LPS and the ability to bind and phagocytose radiolabeled sheep red blood cells was determined. We show that LPS can directly suppress phagocytosis of immunoglobulin G-opsonized and nonopsonized sheep red blood cells (SRBCs) by inflammatory macrophages. Suppression was dose dependent and was observed after 4 h of exposure. This effect lasted for at least 24 h following the removal of LPS. LPS suppressed the binding, rate, and absolute level of phagocytosis via Fc receptors. Phagocytosis via all Fc receptors (Fc gamma RI, Fc gamma RII, and Fc gamma RIII) was suppressed by LPS. Furthermore, suppression was not limited to Fc receptor-mediated phagocytosis because binding and uptake of C3bi-opsonized SRBCs to CR3 receptors was also decreased following LPS treatment. LPS did not exert its effects via the production of interleukin-1 (IL-1), IL-6, tumor necrosis factor alpha, or interferon alpha/beta, because antibodies to these cytokines did not abrogate the effect. The ability of LPS to suppress binding and phagocytosis of microorganisms may contribute to the toxic effects of LPS during gram-negative sepsis by preventing or delaying elimination of bacteria by host macrophages.

Animals↗
PubMed1993

Elements of the Drosophila bithorax complex that mediate repression by Polycomb group products.

The Polycomb (Pc) group genes encode repressors that restrict expression of homeotic genes to precise domains along the anterior-posterior (A-P) axis. We describe germ-line transformation constructs, containing portions of the bxd, iab-2, or iab-3 regulatory regions of the bithorax complex (BX-C), that are controlled by Pc group products in embryos. There are multiple BX-C elements that mediate Pc group control, which we call Pc group response elements (PREs), and they can work when removed from the normal BX-C context. These constructs are each regulated by the genes Polycomb (Pc), extra sex combs (esc), Enhancer of zeste (E[z]), polyhomeotic (ph), Polycomb-like (Pcl), Sex comb on midleg (Scm), Posterior sex combs (Psc), and Additional sex combs (Asx), consistent with multiple Pc group products acting together. Depending upon context, a PRE from the iab-3 region can restrict expression in different A-P positions. Thus, PREs are not specialized for particular parasegments, suggesting that Pc group products do not directly specify A-P boundaries of homeotic expression. Instead, the results support the idea that Pc group products provide stable memory or imprinting of boundaries which are initially specified by gap and pair-rule regulators.

Animals↗
PubMed1993

School nutrition survey.

Food we eat has an important influence on health and well-being. Many eating habits are established in childhood. 456 children aged eight to 12 years participated in this survey of food eaten at school. Of all the food items eaten as a snack, 48.6% were categorised as junk. 75.8% of the sandwiches brought to school for lunch were made with white bread. Of the remaining food items brought for lunch 63.5% were of the junk variety. Compared with those who brought a snack or lunch from home, those given money to buy their own were more likely to eat junk (p < 0.01). Food eaten at school reflects approximately one third of a child's daily food intake but health food practises for even a third of food intake may be of a value for health and long term eating habits. Nutritional education with the reinforcement of high nutritional standards in schools could improve the situation.

Child↗
PubMed1992

The death penalty.

Explore the source record for details and available documents.

Attitude of Health Personnel↗
PubMed1992

A ribosomal ambiguity mutation in the 530 loop of E. coli 16S rRNA.

A series of base substitution and deletion mutations were constructed in the highly conserved 530 stem and loop region of E. coli 16S rRNA involved in binding of tRNA to the ribosomal A site. Base substitution and deletion of G517 produced significant effects on cell growth rate and translational fidelity, permitting readthrough of UGA, UAG and UAA stop codons as well as stimulating +1 and -1 frameshifting in vivo. By contrast, mutations at position 534 had little or no effect on growth rate or translational fidelity. The results demonstrate the importance of G517 in maintaining translational fidelity but do not support a base pairing interaction between G517 and U534.

Base Sequence↗
PubMed1992

The self-perceived health needs of the rural elderly who live alone.

A randomised cross-sectional survey of Public Health Nurses (PHN) registers was carried out in two rural counties, Westmeath and Longford, Ireland. 200 elderly people living alone, consisting of 50 aged 65-74 years in each of the two counties and 50 aged > or = 75 years expressed their health needs in terms of physical, mental and social well-being. 50% lived in accommodation with inadequate bathroom facilities and only 38.9% were content with their current accommodation. 37.9% felt their finances were inadequate while 15.7% were unsure of their eligibility for different entitlements. 17.6% had personal experience of crime. 39.4% lacked a means of obtaining emergency help. The majority (61.7%) perceived themselves as enjoying excellent/good health. The unmet demand for services, other than transport, varied from 11.6% for laundry services to 0% for PHN visits. Transport services were judged inadequate by 51.5% of the study group. It is concluded that by analysing and cross-analysing in terms of variables used in this study, aspects of health care needs could be targetted for different subgroups within the elderly alone group. While not complete in themselves they would help in the targetting of scarce resources.

Aged↗
PubMed1992

Generalized allergic reactions during anesthesia.

Twenty-eight adults with a history of a generalized allergic reaction during anesthesia were investigated. The reactions were systemic in 23 adults, urticaria/angioedema in four, and bronchial obstruction in one adult. The study population and an additional 35 subjects with a history of use of thiopental during anesthesia but without reactions were investigated by methods including thiopental skin test, succinylcholine skin test, and IgE RAST for antibodies to thiopental, succinylcholine, or latex. Among the 28 patients with reactions, 17 had positive thiopental skin tests; 14/28 reactors and 1/35 of the control group had an IgE thiopental RAST value greater than 2 SD above the mean for control sera from ragweed-allergic subjects. The one control subject with a positive thiopental RAST also was the only control subject with a positive thiopental skin test. IgE succinylcholine RAST was negative in all 23 reactor sera tested. The IgE latex RAST was strongly positive in one reactor. In conclusion, evidence of allergy, particularly allergy to thiopental as a possible basis for the reactions, was obtained in greater than 50% of the patients who were investigated. No allergy to succinylcholine was found.

Adolescent↗
PubMed1992

The dissociation of anterograde and retrograde amnesia in a patient with herpes encephalitis.

Establishing the precise relationship between anterograde amnesia (AA) and retrograde amnesia (RA) has implications for psychological and neuroanatomical models of memory. Many patients have been described who demonstrate AA in conjunction with RA or who demonstrate AA with little, or no apparent, RA. Intact anterograde memory in conjunction with deficits on tasks of retrograde memory is rarely encountered. In this paper, we describe a young female patient (LD) whose RA is extremely severe when contrasted with her mild to moderate deficits on tasks of verbal anterograde memory. In addition, on tests of episodic and semantic autobiographical memory, LD appeared more impaired in her recall of specific episodes than of factual information about her past. The importance of this dissociation in RA for the episodic-semantic distinction and the possible role of visual imagery in recalling remote episodic events are discussed.

Adult↗
PubMed1992

Ocular hazards of nebulized bronchodilators.

Three cases of pupillary dilatation associated with the development of acute glaucoma, precipitated by the use of nebulized bronchodilators are described. We suggest measures to reduce the risk of this complication.

Adult↗