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Biomedical subjects

D Roberts

Publications and source records attributed to D Roberts.

At least 91 records · Page 5Linked to original sources
PubMed1999

Stability study on specimens mailed to a state laboratory and tested with the Gen-Probe PACE 2 assay for chlamydia.

BACKGROUND: Although specimen collection is acknowledged to be a critical factor in the testing of chlamydia, rarely do studies examine the effects of specimen transport on laboratory results. GOAL: To compare the results on specimens shipped in a controlled environment with duplicate specimens exposed to environmental conditions such as heat or extended time in transit. STUDY DESIGN: Duplicate specimens were collected from 1,017 women tested at South Carolina public health clinics. One specimen from each woman was shipped by courier and the other by U.S. mail. The results, swab collected first, method of transport, and temperature during shipment were compared for each set of specimens. Specimens were tested with the Gen-Probe PACE 2 test. RESULTS AND CONCLUSIONS: Mailed specimens were exposed to longer transport times and elevated temperatures; despite this, 99% of the results using courier specimens agreed with the mailed specimen results. Eighty-eight women tested positive and 891 women tested negative for chlamydia on both specimens. When the 11 specimens with discrepant results were retested by polymerase chain reaction, 10 were positive for chlamydia, with 9 concurring with the mailed specimen results. Results of specimens in this study were not adversely affected by heat and extended transit times when transported by U.S. Mail.

Adult↗
PubMed1999

Nonepileptic seizures after resective epilepsy surgery.

PURPOSE: To identify factors that are associated with the emergence of nonepileptic seizures (NES) after resective epilepsy surgery. METHODS: Twenty-two patients with medically refractory epilepsy in whom NESs were documented by EEG after resective surgery were compared with a larger series of epilepsy surgery patients on demographic, neurologic, and psychiatric variables. RESULTS: NES tended to become apparent in the first few months after surgery. Patients who developed NESs did not differ from other epilepsy surgery patients in terms of age, IQ, or preoperative psychiatric diagnoses. However, surgical NES patients' neurologic problems and seizures began later in life, the NES group included a larger proportion of female subjects and patients with right hemisphere surgery, and NES patients were more likely to develop non-NES psychiatric problems after surgery. CONCLUSIONS: The heterogeneous collection of behaviors subsumed under the label NESs are determined by multiple factors. Several variables were found to be specifically associated with the development of NES after resective epilepsy surgery: A disproportionate number of postsurgical NES patients are female, they have primary neurologic dysfunction in the right hemisphere, and their epileptic seizures often began after adolescence. We propose that at least one group of patients with somatoform tendencies develop NESs as part of the psychiatric instability that occurs often in the few months after resective surgery.

Adult↗
PubMed1999

Response of ventilator-dependent patients to different levels of pressure support and proportional assist.

The ventilator's response to the patient's effort is quite different in proportional assist ventilation (PAV) and pressure support ventilation (PSV). We wished to determine whether this results in different ventilatory and breathing pattern responses to alterations in level of support and, if so, whether there are any gas exchange consequences. Fourteen patients were studied. Average elastance (E) was 22.8 (range, 14 -36) cm H2O/L and average resistance (R) was 15. 7 (range, 9-21) cm H2O/L/s. The highest PSV support (PSVmax) was that associated with a tidal volume (VT) of 10 ml/kg (20.4 +/- 3.2 cm H2O), and the highest level of PAV assist (PAVmax) was 78 +/- 7% of E and 76 +/- 7% of R. Level of assist was decreased in steps to the lowest tolerable level (PSVmin, PAVmin). Minute ventilation, VT, ventilator rate (RRvent), and arterial gas tensions were measured at each level. We also determined the patient's respiratory rate (RRpat) by adding the number of ineffective efforts (DeltaRR) to RRvent. There was no difference between PSVmin and PAVmin in any of the variables. At PSVmax, VT was significantly higher (0.90 +/- 0.30 versus 0.51 +/- 0.16 L) and RRvent was significantly lower (13.2 +/- 3.9 versus 27.6 +/- 10.5 min-1) than at PAVmax. The difference in RRvent was largely related to a progressive increase in ineffective efforts on PSV as level increased (DeltaRR 12.1 +/- 10.1 vs 1.4 +/- 2.1 with PAVmax); there was no significant difference in RRpat. The differences in breathing pattern had no consequence on arterial blood gas tensions. We conclude that substantial differences in breathing pattern may occur between PSV and PAV and that these are largely artifactual and related to different patient-ventilator interactions.

Aged↗
PubMed1999

Randomized placebo-controlled trial of a 42-Day tapering course of dexamethasone to reduce the duration of ventilator dependency in very low birth weight infants.

OBJECTIVE: To assess the effect on duration of ventilator dependency of a 42-day tapering course of dexamethasone in very low birth weight neonates. METHODS: Infants (N = 118) were assigned randomly, within birth weight/gender strata, to treatment with either a 42-day tapering course of dexamethasone or an equal volume of saline as placebo. Entry criteria were 1) birth weight <1501 g; 2) age between 15 and 25 days; 3) <10% decrease in ventilator settings for 24 hours and FIO2 >/=0.3; 4) absence of patent ductus arteriosus, sepsis, major congenital malformation, congenital heart disease; and 5) no evidence of maternal HIV or hepatitis B infection. The dosage schedule was 0.25 mg/kg bid for 3 days, then 0.15 mg/kg bid for 3 days, then a 10% reduction in the dose every 3 days until a dose of 0.1 mg/kg had been given for 3 days, from which time a dose of 0.1 mg/kg qod was continued until 42 days after entry. The primary endpoint was the number of days on assisted ventilation after study entry. Secondary outcomes of interest included days on supplemental oxygen, days of hospitalization, and potential adverse effects, such as infection, gastrointestinal bleeding, left ventricular hypertrophy, and severe retinopathy of prematurity. RESULTS: Infants in the dexamethasone- and placebo-treated groups were similar in terms of baseline attributes, including birth weight, gestational age, gender, race, and ventilator settings at entry. Infants treated with dexamethasone were on assisted ventilation and supplemental oxygen for fewer days after study entry (median days on ventilator, 5th and 95th percentiles, 13 [1-64] vs 25 [6-104]; days on oxygen, 59 [6-247] vs 100 [11-346]). No differences were found in risk of death, infection, or severe retinopathy. In subgroup analyses, the association of dexamethasone with more rapid weaning from the ventilator was weaker among infants enrolled before the 16th day of life, infants with chest radiographs showing cystic changes and/or hyperinflation, and infants requiring an FIO2 >/=0.7 or a peak inspiratory pressure >/=19 at study entry. CONCLUSIONS: A 42-day tapering course of dexamethasone decreases the duration of ventilator and oxygen dependency in very low birth weight infants and is not associated with an increased risk of short-term adverse effects.

Confounding Factors, Epidemiologic↗
PubMed1999

Proprioception in people with anterior cruciate ligament-deficient knees: comparison of symptomatic and asymptomatic patients.

STUDY DESIGN: Nonrandomized prospective study. OBJECTIVE: To evaluate proprioception in 2 groups of patients with anterior cruciate ligament (ACL) deficiency who had different severity of symptoms. BACKGROUND: Defective proprioception has previously been found in patients with ACL-deficient knees. It has been suggested that sensory receptors of the ACL and other knee joint ligaments contribute to proprioception and knee joint function and stability. METHODS AND MEASURES: A total of 17 patients with ACL deficiency (mean [SD] age, 28.8 +/- 5.6 years; range, 22-39 years) with few, if any, symptoms were compared with 20 patients with ACL deficiency (mean [SD] age, 26.6 +/- 6.1 years; range, 18-39 years) having instability and episodes of giving way. The groups were compared with each other and with an age-matched reference group of 19 nonimpaired subjects. Their mean (SD) age was 25.6 +/- 3.7 years (range, 20-37 years). Three tests of proprioception were used: threshold to detection of passive motion from 2 starting positions (20 degrees and 40 degrees of knee flexion) toward flexion and extension, active reproduction of a 30 degrees passive angle change, and visual reproduction of a 30 degrees passive angle change. The Wilcoxon rank sum test was used for between-group comparisons. RESULTS: Symptomatic patients had higher threshold to detection of passive motion in their injured side in the flexion trial from 20 degrees (median of 1.5 degrees vs median of 0.5 degree) and in the extension trial from 40 degrees (median of 1.0 degree vs median of 0.5 degree) than the asymptomatic patients. No differences were found in the other threshold tests, active or visual reproduction tests. CONCLUSIONS: Patients with severe symptoms related to ACL deficiency were found to have inferior proprioceptive ability in some measurements compared with patients with a good knee function. The findings indicate that proprioceptive deficits might influence the outcome of an ACL injury treated nonoperatively.

Adult↗
PubMed1999

Microbiological quality of retail imported unprepared whole lettuces: a PHLS Food Working Group Study. Public Health Laboratory Service.

A study of imported unprepared whole lettuces sampled from supermarkets, greengrocers, shops, and market stalls found that all were of acceptable microbiological quality. Twenty-seven out of 151 (18%) imported lettuce samples had Enterobacteriaceae levels of 10(4) CFU/g or more. However, these bacteria that constitute part of the natural microflora of unprepared vegetables may also be derived from the soil and/or by poor handling. The pathogens, Salmonella spp., Shigella spp., Campylobacter spp., Escherichia coli O157:H7, Vibrio cholerae, Listeria monocytogenes, and also Escherichia coli, an indicator of fecal contamination, were not detected in any imported lettuces, indicating that hygiene, harvesting, and production practices were good. Imported lettuces with Enterobacteriaceae levels of 10(4) CFU/g or more varied with type of retail premises and the temperature at which the lettuces were displayed. Samples from greengrocers, shops, and market stalls were more likely to contain Enterobacteriaceae at levels in excess of 10(4) CFU/g than those from supermarkets.

Colony Count, Microbial↗
PubMed1999

Proficiency testing in the food microbiology laboratory.

Laboratories offering a quality service for the microbiological examination of food must implement a quality assurance system. An effective system should, in addition to daily quality control of procedures, consumables, and equipment, include external laboratory accreditation to a recognised standard, the use of validated test methods, and participation in an external quality assessment (proficiency testing) scheme. External quality assessment (EQA) is a system in which samples of known but undisclosed content are introduced into a laboratory's routine testing procedure, in other words, a challenge to those procedures. There are a number of EQA schemes available to food microbiology laboratories, either offering freeze dried mixtures of organisms as simulated foods or preweighed portions of spiked dried foods. There are a number of important requirements for an effective EQA scheme and a range of benefits from participation to a laboratory. These are discussed in the light of experience with the development of a specific scheme.

Food Microbiology↗
PubMed1999

Fatal laryngeal injury in an achondroplastic dwarf secondary to airbag deployment.

We report the case of an unrestrained driver with achondroplastic dwarfism who suffered a fatal anterior neck injury when her airbag deployed as she rear-ended another vehicle at 30-40 mph. Her short stature and short limbs required her to sit within a handbreadth of the steering wheel, which probably allowed the airbag or airbag cover to strike her neck as it opened. This is the first reported case of fatal injury to a driver with achondroplastic dwarfism.

Accidents, Traffic↗
PubMed1999

Neutralising antibody responses to two doses of measles vaccine at 5 and 13 months of age in the United Kingdom.

Fifty-three children born in the United Kingdom between April 1993 and July 1994 were given two doses of measles vaccine, at 5 and 13 months of age, and their neutralising antibody reports were studied to assess the feasibility of protecting infants (aged 1 to 11 months) in the event of an outbreak or who were due to travel abroad. Sixteen infants responded at 5 months, an additional 35 responded at 13 months and two did not respond. The responses were inversely related to the levels of maternal antibodies (p < 0.0001). Infants who responded at 5 months also produced higher responses at 13 months than those who did not respond initially (p = 0.0001). No serious side effects were encountered. These data suggest that measles vaccine protects 30% of infants at 5 months and that a second dose at 13 months results in almost universal seroconversion.

Analysis of Variance↗
PubMed1999

5-Aminolevulinic acid photosensitization of dysplastic Barrett's esophagus: a pharmacokinetic study.

Photodynamic therapy (PDT) using 5-aminolevulinic acid (ALA)-induced protoporphyrin IX (PpIX) may have a role in the treatment of dysplastic Barrett's esophagus. Before ALA-induced PDT can be used clinically, optimum treatment parameters must be established. In this study of 35 patients, the issues of drug dosage, time interval between drug and light delivery and side effects of oral ALA administration are addressed. Spectrofluorometric analysis of tissue samples demonstrates that oral ALA administration induces porphyrin accumulation in esophageal tissues, with maximum levels at 4-6 h. High-performance liquid chromatography confirms the identity of this porphyrin as PpIX, and fluorescence microscopy analysis demonstrates that it preferentially accumulates in the esophageal mucosa, rather than in the underlying stroma. Side effects of ALA administration included malaise, headache, photosensitivity, alopecia, transient derangement of liver function, nausea and vomiting. Fewer side effects and less hepatic toxicity was seen with 30 mg/kg than 50 mg/kg ALA. In conclusion, oral ALA administration induces preferential PpIX accumulation in the esophageal mucosa, with peak PpIX fluorescence noted at 4 h and minimal systemic toxicity at a dose of 30 mg/kg.

Aminolevulinic Acid↗
PubMed1998

Characterization of molecular defects in isovaleryl-CoA dehydrogenase in patients with isovaleric acidemia.

Isovaleryl-CoA dehydrogenase (IVD) is a homotetrameric mitochondrial flavoenzyme which catalyzes the conversion of isovaleryl-CoA to 3-methylcrotonyl-CoA. PCR of IVD genomic and complementary DNA was used to identify mutations occurring in patients with deficiencies in IVD activity. Western blotting, in vitro mitochondrial import, prokaryotic expression, and kinetic studies of IVD mutants were conducted to characterize the molecular defects caused by the amino acid replacements. Mutations leading to Arg21Pro, Asp40Asn, Ala282Val, Cys328Arg, Val342Ala, Arg363Cys, and Arg382Leu replacements were identified. Western blotting of fibroblast extracts and/or in vitro mitochondrial import experiments indicate that the seven precursor IVD mutant peptides, and a previously identified IVD Leu13Pro mutant, are synthesized and imported into mitochondria. While the IVD Leu13Pro, Arg21Pro, and Cys328Arg mutant peptides are rapidly degraded following mitochondrial import, the other mutant peptides exhibit greater mitochondrial stability, though less than the wild-type enzyme. Active IVD Ala282Val, Val342Ala, Arg363Cys, and Arg382Leu mutants were less stable than wild type when produced in Escherichia coli. The Km values of purified IVD Ala282Val, Val342Ala, and Arg382Leu mutants are 27.0, 2. 8, and 6.9 microM isovaleryl-CoA, respectively, compared to 3.1 microM for the wild type, using the electron-transfer flavoprotein (ETF) fluorescence quenching assay. The catalytic efficiency per mole of FAD content of these three mutants is 4.8, 17.0, and 17.0 microM-1*min-1, respectively, compared to 170 microM-1*min-1 for wild type.

Amino Acid Metabolism, Inborn Errors↗
PubMed1998

Reproductive sequelae in female rats after in utero and neonatal exposure to the phytoestrogen genistein.

OBJECTIVE: To determine reproductive sequelae in female rats after in utero and lactational dietary exposure to genistein. DESIGN: Experimental animal study. SETTING: University laboratory. ANIMAL(S): Sprague Dawley rats. INTERVENTION(S): Pregnant rats were fed control rat chow or rat chow incorporated with genistein (approximately 50 microg/d) beginning on day 17 of gestation and continuing until the end of lactation (postpartum day 21). Genistein-exposed female pups were divided into two groups on day 21. One group continued to receive a genistein-added diet (G70); the other group was changed to a control diet (Ex-G). At necropsy (days 21 and 70), blood and reproductive tissues were collected. MAIN OUTCOME MEASURE(S): Serum levels of gonadotropins and gonadal steroids and histopathologic examination of the ovaries. RESULT(S): The weight of the ovaries and uterus and serum levels of E2 and progesterone in genistein-exposed rats on day 21 (G21) were significantly reduced compared with control rats. On day 70, serum levels of E2, progesterone, LH, and FSH were similar in all groups. Atretic follicles and secondary interstitial glands were more common in G70 and Ex-G rats compared with control rats. Cystic rete ovarii was observed in some G70 and Ex-G rats. CONCLUSION(S): Our data indicate that in utero and lactational exposure to dietary genistein adversely affects reproductive processes in the adult female rat.

Animals↗
PubMed1998

Quantitative analysis of HBY 097 and its metabolites in human serum and urine by HPLC.

Two HPLC methods were developed: one for the quantitation of HBY 097 reverse transcriptase inhibitor and its metabolites M2 and M3 in human serum, and one for the quantitation of metabolite M5 in urine. The HPLC procedure for the quantitation of HBY 097 and its metabolites M2 and M3 in human serum involved protein precipitation with acetonitrile followed by automated on-line trace enrichment. The HPLC procedure for the analysis of metabolite M5 in urine involved enzymatic hydrolysis of urine with beta-glucuronidase to convert metabolite M5 (glucuronide of M3) to M3. Reverse phase chromatographic separation with gradient elution. UV detection at 335 nm, and internal standard were used to quantitate analytes in both procedures. The lower quantitation limits were 25 ng ml-1 for HBY 097 and metabolites M2 and M3 in serum, and 0.5 microgram ml-1 for the metabolite M5 in urine measured as metabolite M3 after hydrolysis. The HBY 097 and metabolite M3 concentrations were specific but metabolite M2 was semi-specific because the two diastereomers of M2 were not resolved by the present chromatographic procedure. Both procedures were applied to the quantitation of HBY 097 and its metabolites in serum and urine of HIV positive patients who were enrolled in a clinical study of drug safety and pharmacokinetics.

Antiviral Agents↗
PubMed1998

Molecular fingerprinting defines a strain of Salmonella enterica serotype Anatum responsible for an international outbreak associated with formula-dried milk.

Molecular analyses based on plasmid profile typing and pulsed-field gel electrophoresis have defined a strain of Salmonella enterica serotype Anatum associated with the consumption of a particular brand of formula-dried milk responsible for an outbreak in late 1996/early 1997 involving 15 infants and 2 relatives in the UK, and 2 infants in France. The study has demonstrated the value of laboratory-based surveillance involving identification of the outbreak strain at the molecular level coupled with food microbiology and targeted epidemiological investigations, and has highlighted the importance of rapid communication and subsequent international collaboration through the European Union-funded Salm-Net salmonella surveillance network.

Animals↗