PubMed Health⌕ Search

Biomedical subjects

M W Roberts

Publications and source records attributed to M W Roberts.

At least 19 recordsLinked to original sources
PubMed2005

Activation of oxygen at metal surfaces.

Oxygen chemisorption at metal surfaces has been shown through a combination of scanning tunnelling microscopy and photoelectron spectroscopy to involve transient states that provide low energy pathways for a wide range of surface reactions including the catalytic oxidation of ammonia and hydrocarbons. The kinetically 'hot' transients are disordered and mobile, become unreactive when they form ordered structures, and are characterized by non-classical kinetic behaviour. The role of surface additives (caesium) in controlling oxygen structures and the implications of oxygen transients for theory and reaction mechanisms in applied catalysis are considered.

Adsorption↗
PubMed2001

Clinic observations of structured parent-child interaction designed to evaluate externalizing disorders.

Observing structured parent-child interaction in clinic analogs has been a tradition in child clinical assessment since the 1960s. The clinic analog is designed to re-create important conditions from natural contexts such that dysfunctional parent-child patterns can be observed and modified. To those basic goals, the modern clinician would add diagnosis and treatment evaluation. Three classes of parent-child clinic analogs designed to evaluate preadolescent children with externalizing disorders were reviewed: free play, parent-directed play, and parent-directed chores. Free-play analogs and parent-directed chore analogs were found to have merit, but remain psychometrically underdeveloped. Practitioner reliance on questionnaires and interviews appears likely to continue until observational analogs have attained sufficient psychometric qualities to facilitate routine clinical decisions.

Child↗
PubMed2001

A cost analysis of treating pediatric dental patients using general anesthesia versus conscious sedation.

The purpose of this pilot study is to report a cost comparison of general anesthesia (GA) versus oral conscious sedation (CS) for pediatric dental patients. The study sample included 22 children whose parents or guardians selected GA care for their child. Selection criteria limited inclusion to healthy children (American Society of Anesthesiologists' classification I) aged 24-60 months. The subjects acted as their own comparison group to an estimation CS model. Models were developed to assess societal costs for treatment under GA and CS. Treatment rendered was equalized using the dental relative based value unit scale.

Anesthesia, Dental↗
PubMed2000

The social impact of multiple sclerosis--a study of 305 patients and their relatives.

PURPOSE: to assess the effects of multiple sclerosis (MS) on the patients' ability to fulfil their chosen family and social roles and to examine the impact of the disease on their relatives. METHODS: a population-based survey of all known patients with MS and their relatives in Hampshire County, England, between 1986 and 1989. RESULTS: Seventy-four% of the total study population of 411 completed the study. The patients' mean age was 48.3 years (range 19-82) and the mean disease duration was 15.8 years. About 16% of patients were depressed on a mood rating scale and a similar number also exhibited symptoms of anxiety. The marital status of most patients had not changed since the onset of MS but 53% of those who were employed at the time of diagnosis gave up their jobs and the standards of living of 37% of patients and their families had declined as a direct result of the disease. The ability to continue in gainful employment or to maintain social contacts and leisure activities correlated with the course and severity of the disease and cognitive function. Most carers reported symptoms that clearly related to organic pathologies, anxiety and symptoms of depression. The occurrence of these symptoms was associated with disease severity. The professional career of 57% of relatives was also adversely affected by the patient's illness. CONCLUSIONS: MS has a profound impact on the patients' social roles and their relatives' well-being. In contrast to previous studies, a high divorce/separation rate among patients with MS was not observed. Severe disability and cognitive impairment are predictors of loss of employment, decline in the standards of living and withdrawal from social and leisure activities among patients and are strong indicators of stress among relatives.

Adult↗
PubMed2000

Terminal deoxynucleotidyl transferase-negative acute lymphoblastic leukemia.

OBJECTIVE: Terminal deoxynucleotidyl transferase (TdT) is a useful marker in the diagnosis of acute lymphoblastic leukemia (ALL) (French-American-British [FAB] L1 and L2) and is most useful in distinguishing ALL from mature B-lymphoid neoplasms, such as Burkitt lymphoma (FAB L3) and other lymphoid malignancies. The frequency of TdT-negative ALL is not known. Here we report 3 TdT-negative ALL cases that met the criteria for T-cell ALL. DESIGN: We reviewed approximately 200 cases of ALL retrieved from the database at our institution. All cases were evaluated using Wright-Giemsa, myeloperoxidase, butyrate, and TdT staining; immunophenotyped using flow cytometry; and studied using Southern blot analyses for T-cell receptors and immunoglobulin gene rearrangement. RESULTS: All ALL cases (L1 and L2) were TdT-positive, except for 3 cases that were of early T-cell lineage. None of the 3 cases demonstrated positivity for TdT in immunofluorescence staining with polyclonal antibodies or flow cytometry with monoclonal antibodies. Flow cytometric analysis confirmed a pre-T-cell immunophenotype in all 3 cases. One of the cases showed rearrangement of a T-cell antigen receptor and immunoglobulin heavy chain (J(H)). A second case showed germline configuration of T-cell receptors, but also showed rearrangement of the J(H), despite the expression of T-cell markers only.

Adult↗
PubMed1998

A comparison of two measurements of child compliance with normal preschool children.

Observed normal preschool children from 2 through 5.9 years of age and their mothers using 2 established measurements of child compliance: the Compliance Test and the Clinic Task Analog. The diagnosis of oppositional defiant disorder as defined by the Diagnostic and Statistical Manual of Mental Disorders (4th ed., American Psychiatric Association, 1994) currently requires subjective integration of interview, questionnaire, and behavioral data. Knowledge of normal child behavior within a parent-controlled task context is needed. Normal 4- and 5-year olds were found to be more compliant than were normal 2- and 3-year olds; no sex effects were detected. The Compliance Test yielded stronger age associations, better observer reliability, and more individual differences than the Clinic Task Analog. Clinic Task Analog data masked child compliance, probably as a result of maternal instruction-giving style. The Compliance Test is recommended for diagnostic purposes over the Clinic Task Analog.

Attention Deficit and Disruptive Behavior Disorder↗
PubMed1998

Fluoride supplement prescribing and dental referral patterns among academic pediatricians.

OBJECTIVE: To determine how well the current fluoride supplementation schedule was known by academic pediatricians and to examine the fluoride supplement prescribing and dental referral practices among primary care faculty pediatricians at four medical centers. SETTING: Four university medical centers in North Carolina. SUBJECTS: Primary care faculty pediatricians. METHOD: A questionnaire pretested for clarity was distributed to all identified full-time primary care pediatric faculty (42 members). RESULTS: A total of 40 completed questionnaires were returned. Thirty-seven (93%) primary care faculty pediatricians reported that they routinely addressed the need for fluoride supplements for their patients, but only 28 (70%) determined the fluoride content of the drinking water before prescribing supplements. Thirty-five (87.5%) began supplements at the correct age, but fewer knew the correct doses for children of various ages. Only 23 (58%) referred their patients for oral examination and preventive care before the age of 36 months, contrary to American Academy of Pediatrics recommendations. CONCLUSIONS: Pediatricians in an academic setting would be expected to be more knowledgeable of current recommendations than those in private practice. Failure to know and teach correct fluoride supplement recommendations and failure to recommend early professional dental involvement can result in less than optimum oral health.

Academic Medical Centers↗
PubMed1997

Cardiopulmonary responses to intravenous infusion of soluble and relatively insoluble gases.

BACKGROUND: Carbon dioxide is the current gas of choice for pneumoperitoneum, but hemodynamic and acid-base effects secondary to its systemic absorption have been reported. Various studies have suggested inert gases as alternatives. METHODS: We studied the cardiopulmonary responses to intravenous infusion of carbon dioxide, nitrous oxide, argon, helium, and nitrogen in anesthetized swine. The gas was infused into the femoral vein at a rate of 0.1 ml . kg-1 . min-1 for 30 min. The changes in end-tidal CO2, mean arterial pressure, hemodynamics, and arterial blood gases were compared to baseline values. RESULTS: No animals died during infusion of the soluble gases (CO2 and N2O). Three of the five pigs infused with nitrogen died suddenly at 20 and 30 min of infusion. The animals in the insoluble gas groups (Ar, He, N2) experienced clinical pulmonary gas embolism and severe acidemia, hypercapnea and tachycardia. CONCLUSIONS: Venous gas embolism is poorly tolerated when the gas is relatively insoluble. Insoluble gases should not be used for pneumoperitoneum when there is any risk of venous gas embolism.

Animals↗
PubMed1995

A capillary zone electrophoresis assay for the nucleoside transfer enzyme adenosine diphosphate-glucose pyrophosphorylase.

Conditions are described for a capillary zone electrophoresis-based assay of ADP-glucose pyrophosphorylase, the first enzyme in the de novo synthesis for alpha-glucan synthesis in plants and bacteria. ATP, ADP-glucose, and other adenine derivatives are effectively resolved and quantified in 12 min of electrophoresis. The method requires minimal sample manipulations and no postincubation hydrolyses, is effective over a wide range of enzyme and substrate concentrations, has a sensitivity comparable to radioisotope assays, and yields reproducible results in either the forward and reverse directions. Moreover, the assay is applicable to other enzymes that utilize nucleosides or their bases as substrates or products.

Adenine Nucleotides↗
PubMed1994

Tricho-dento-osseous syndrome. Features of the hair and teeth.

Tricho-dento-osseous syndrome is a rare autosomal dominant hereditary disorder characterized by curly hair, enamel hypoplasia, taurodont teeth, and thickened cortical bone. A large kindred with this syndrome has been identified in North Carolina and characterized by pedigree analysis and clinical evaluation. Hair samples (N = 3) and an exfoliated primary tooth (N = 1) from persons with tricho-dento-osseous syndrome and hair and teeth from unaffected persons were examined. Scanning electron microscopy showed that the hair shaft morphology, diameter, and cuticular pattern and periodicity were similar for the tricho-dento-osseous syndrome and control samples. The affected tooth was examined using light microscopy and a scanning electron microscope that showed pitting hypoplasia of the enamel surface, an extremely large pulp chamber, and dentin that appeared structurally normal. The affected enamel was uniformly thin, only 10% the thickness of the control enamel. The bulk of this enamel showed no prism formation. This study indicates that although hair with tricho-dento-osseous syndrome often is clinically curly, it can be straight, and it does not appear to have unique ultrastructural features that are of diagnostic benefit. The dental characteristics of tricho-dento-osseous syndrome were the most consistent feature seen in this kindred.

Abnormalities, Multiple↗
PubMed1994

Targeting of mRNAs to domains of the endoplasmic reticulum.

The targeting of proteins to specific regions of the cell by signal elements within the polypeptide sequence has received much attention, but proteins can also be directed to their appropriate cellular locations by localization of their mRNAs. This mechanism is seen clearly in polar cells like germ and embryonic cells, neurons and epithelia. Recent evidence indicates that mRNAs may also be localized to morphologically and functionally distinct endoplasmic reticulum membranes, thereby facilitating sorting of the proteins they encode to subdomains of the reticulum or to polarized plasma membranes.

Journal Article↗
PubMed1992

Clinical evaluation of a composite resin system with a dentin bonding agent for restoration of permanent posterior teeth: a 3-year study.

This study evaluated the clinical performance of a visible light-cured small particle bimodally filled hybrid condensable composite resin system that included a dentin bonding agent compared with an amalgam alloy in class II restorations of permanent teeth. A total of 108 restorations were placed in 34 patients. Fifty-three composite resin and 55 amalgam restorations were inserted. Each restoration was evaluated immediately after placement and then on an annual basis for a 3-year period using the Public Health Service (PHS) criteria. In addition, the Moffa-Lugassy scale was used to measure the loss of material on the occlusal surface of these materials. One hundred percent of the resin and amalgam restorations were evaluated, measured, and reasons for replacement were recorded over the 3-year period. There was no significant difference (p greater than 0.05) in the clinical performance of the composite resin and the amalgam when evaluated by the PHS criteria. Analyses of wear at each of the three annual recall periods did not reveal any significant difference (p greater than 0.05) between the two restorative materials when measured by the Moffa-Lugassy scale.

Bicuspid↗
PubMed1992

Two natal maxillary molars. Report of a case.

A 20-day-old black male infant with two rare posterior natal teeth was referred for examination and care. Oral radiographs suggested that the teeth were the right and left maxillary primary molars. The hypermobile teeth and associated suspicious soft tissue masses were removed. Histologic examination revealed irregular tooth structures and infiltrate consistent with inflamed dental follicles.

Humans↗
PubMed1992

The effect of ribosomal protein S1 from Escherichia coli and Micrococcus luteus on protein synthesis in vitro by E. coli and Bacillus subtilis.

We have designed a set of nine plasmids containing the Bacillus pumilis cat gene with one of three Shine-Dalgarno (SD) sequences (weak, strong or stronger) and one of three initiation codons (AUG, GUG or UUG). These constructions have been used to determine the effect of ribosomal protein S1, SD and initiation codon sequences and Escherichia coli ribosomal protein S1 on translation in vitro by E. coli and B. subtilis ribosomes. Translation of these nine constructions was determined with three types of ribosomes: E. coli containing ribosomal protein S1, E. coli depleted of S1, and B. subtilis which is naturally free of S1. E. coli ribosomes were able to translate all nine transcripts with variable efficiencies. B. subtilis and S1-depleted E. coli ribosomes were similar to each other and differed from non-depleted E. coli ribosomes in that they required strong or stronger SD sequences and were unable to translate any of the weak transcripts. Addition of S1 from either E. coli or Micrococcus luteus, a Gram-positive bacterium, enabled S1-depleted E. coli ribosomes to translate mRNAs with weak SD sequences but had no effect on B. subtilis ribosomes. AUG was the preferred initiation codon for all ribosome types; however, B. subtilis ribosomes showed greater tolerance for the non-AUG codons than either type of E. coli ribosome. The presence of a strong or stronger SD sequence increased the efficiency by which E. coli ribosomes could utilize non-AUG codons.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacillus subtilis↗
PubMed1991

Accurate in vitro transcription of plant promoters with nuclear extracts prepared from cultured plant cells.

A simple method is presented for the preparation of nuclear extracts from suspension cultures of rice, wheat and tobacco cells. These extracts are shown to be capable of RNA Polymerase II-dependent transcription from two plant promoters in vitro; a 250 bp fragment of a wheat gliadin promoter containing sequences from -167 bp to +83 relative to the in vivo transcriptional initiation site and two fragments of the CaMV 35S promoter, containing sequences from -419 to +17, and from -90 to +17. Using the rice extract, transcription is shown to be extract-dependent, DNA-dependent, alpha-amanatin-sensitive, promoter-dependent, and accurate with respect to initiation site selection on the gliadin promoter and the -90 to +17 35S promoter, but not accurate on the -419 to +17 35S promoter.

Base Sequence↗
PubMed1991

Bulimia nervosa. Its effect on salivary chemistry.

Erosion of the dental hard tissues and enlarged parotid and submandibular saliva glands are commonly associated with bulimia nervosa. In 15 patients and controls, no significant difference was detected in the concentrations of potassium, chloride, calcium, urea nitrogen or albumin. There was also no evidence of olfactory dysfunction.

Adult↗