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At least 973 records · Page 54Linked to original sources
PubMed2000

The development of immunoassays to four biological threat agents in a bidiffractive grating biosensor.

A critical need exists for a field deployable biosensor to detect environmental infectious agents in collected air samples rapidly, with sensitivity and specificity approaching that of standard laboratory procedures. The ideal sensor would analyze unknown samples in minutes, have programmable operation for unattended sample analysis, and be capable of multiple agent analysis for a number of agents. The goal of this project was to further the development of the bidiffractive grating biosensor (BDG) created through collaboration between Battelle Memorial Institute (BMI), Hoffman LaRoche (HLR), and the Naval Medical Research Command (NMRC). This manuscript details the development, optimization, and evaluation of this device as a potential field deployable biosensor. Well-characterized immunochemical reagents developed by the Biological Defense Research Department (BDRD) at NMRI were employed to develop assays in the BDG. These results were compared to those obtained with antigen capture enzyme linked immunosorbent assays (ELISAs). Four separate antigens were evaluated: Staphylococcus aureus enterotoxin B (SEB), ricin (RIC), Francisella tularensis (FT), and Clostridium botulinum toxin (BOT).

Biological Warfare↗
PubMed1988

[Role of the electrophysiologic examination in the diagnosis of Bassen-Kornzweig syndrome].

An autosomal recessive disorder, abetalipoproteinemia or Bassen-Kornzweig disease, concerning two sisters are described. This disorder, clinically similar to Friedreich ataxia, should be examined by electrophysiological and laboratory procedures because of the possibility of treatment by high doses of vitamin A and E. The routine electrophysiological examination of the two sisters revealed a degenerative spinocerebellar and peripheral nervous process which confirmed the damage of large myelinated fibers, as reported in the literature: neurogenic muscular atrophy of distal muscles, polyphasic motor unit potentials, moderately decrease of lower motor and sensory nerve conduction rates, and reduced amplitude of evoked responses in sensory nerves and muscles. We stress out the diagnostic value of the heterogenous conduction decrease in the distal motor fibers, signs of processes of demyelination or distal regeneration.

Abetalipoproteinemia↗
PubMed2003

An unexpected distribution of sodium concentration in serum specimens stored for more than 30 years.

PURPOSE: Sera from over 50,000 pregnant women in the Collaborative Perinatal Project have been frozen at -20 degrees C since 1959 to 1966, and with the health data on their offspring constitute a resource that is still actively used. In two studies using these specimens, we measured sodium concentration to assess desiccation. METHODS: Sodium was measured in over 5,000 specimens by two different methods. For 10 specimens with unusually low sodium values, a substudy was done to investigate the cause. RESULTS: High sodium levels (>140 mmol/L) were present in more than 20% of specimens, and levels were unusually low (<130 mmol/L) in more than 40% of specimens. The substudy showed that filtering the specimens increased sodium levels and that about 14% of the sodium was trapped in particulate matter. CONCLUSIONS: High sodium levels in these specimens were probably due to desiccation and possibly to leaching of sodium from the glass containers. Low sodium levels were probably caused by the particulate matter, which clogged the analytical sampling devices and also trapped sodium. In serum specimens that have been stored for long periods, use of routine laboratory procedures for analysis can yield erroneous results. Furthermore, measured analyte levels can be affected by more than just degradation and desiccation.

Adult↗
PubMed2003

A new removable implant analog.

A new implant analog system that improves the efficiency of the implant restoration's fabrication process is described. This 2-piece analog contains an outer plastic sleeve that is retained within the stone cast. The inner portion, a metal analog, can be easily removed and replaced within the plastic sleeve. Because the metal analog is removable, the time-consuming process of screwing and unscrewing the prosthesis- or abutment-retaining screws during laboratory procedures can be minimized. The prosthesis can remain secured to the analog during waxing, metal finishing, and porcelain buildup, yet is easily removed from the cast for inspection.

Crowns↗
PubMed1999

Drugs and driving: a retrospective study of the analyses of blood and urine specimens submitted to the Lothian and Borders Police Forensic Laboratory.

A comprehensive review of 75 samples of both blood and urine from 72 different drivers suspected of being impaired by drugs in the Lothian and Borders Police Force, Scotland area of jurisdiction, between 1st January 1995 and 2nd May 1997, was undertaken. The police reports, analytical results and criminal conviction records relating to each of the drivers were examined. This provided useful information concerning differences in laboratory procedures and produced a profile of the average drugged driver. The average age of the drivers was 23 years. Only two females were within the sample. Drugs were found in 65 cases (86.7%). Polydrug use was found in seven cases (9.3%). The drugs found, in order of frequency, were benzodiazepines (40%), cannabinoids (24%), alcohol (16%), methadone (12%), dihydrocodeine (9.3%), ecstacy (5.3%), amphetamine (2.7%), volatiles (1.3%) and morphine (1.3%). 90.3% of the drivers had previous convictions for criminal offences and 47.2% had convictions for drugs-related offences. Recommendations concerning police and medical training are discussed with particular reference to the Drug Recognition Expert program.

Journal Article↗
PubMed2001

Sensory modulation dysfunction in children with attention-deficit-hyperactivity disorder.

This study investigates the presence of sensory modulation dysfunction (SMD) among children with attention-deficit-hyperactivity disorder (ADHD). Twenty-six children with ADHD (mean age 8.3 years, 18 males, 8 females), and 30 typically developing children (mean age 8.2 years, 21 males, 9 females) were tested using a laboratory procedure that gauges responses to repeated sensory stimulation by measuring electrodermal reactivity (EDR). Parental report measures of limitations in sensory, emotional, and attentional dimensions were administered using the Short Sensory Profile, the Leiter International Performance Scale-Revised, Parent Rating subscales, and the Child Behavior Checklist (CBCL). Compared to the typical sample, the children with ADHD displayed greater abnormalities in sensory modulation on both physiological and parent-report measures. The children with ADHD also displayed more variability in responses. Within the group with ADHD, levels of SMD were highly correlated with measures of psychopathology on the CBCL. Implications of findings relate to the importance of considering sensory processing abilities in a subgroup of children with ADHD.

Adolescent↗
PubMed1986

Factors affecting the reliability of the McMaster technique.

Factors detracting from the reliability of faecal egg counts based on the McMaster technique include variation in flotation time (interval between loading chamber and counting eggs) and sample dilution (ratio of faecal material to salt solution). We recommend standardization of both these variables as normal laboratory procedure, and propose optima of a 30 minute flotation time and a sample dilution of 15 ml salt solution/g faeces for use of the McMaster technique in the estimation of the fecundity of Heligmosomoides polygyrus (Nematoda).

Animals↗
PubMed1995

Replication, differentiation, growth and the virulence of Trypanosoma brucei infections.

This study had 2 objectives: first, to investigate how the processes of slender form replication, of differentiation from dividing slender to non-dividing stumpy forms, and of stumpy mortality, combine to determine the initial (acute-phase) growth rate of Trypanosoma brucei populations; second, to determine how acute-phase growth rates influence parasite densities during the subsequent, chronic phase of infection. During the acute phase, slender and stumpy populations both grew approximately exponentially, the latter more slowly than the former. Mathematical models showed how this difference in slender and stumpy growth rates can be explained in terms of heterogeneous replication and differentiation rates. Stumpy life-expectancy was determined for one stock and found to be age-dependent with a half-life of 48-72 h, much larger than observed population doubling times of 5-10 h. A comparison of cloned stocks showed that the highest parasite densities during the chronic phase were associated with the highest acute-phase growth rates of both the whole parasite population and of the subpopulation of slender forms. By contrast, high chronic-phase parasitaemias artificially produced following rapid syringe passage were associated with low acute-phase growth rates of slender forms. Syringe-passaging is a laboratory procedure which selects for virulent parasites, but these parasites behave differently from naturally virulent stocks.

Animals↗
PubMed1998

Molecular detection of parasitic protozoa.

The development of molecular diagnostic methods, particularly those utilizing PCR for the detection of parasitic protozoa will contribute greatly to the identification and control of these pathogens, by increasing speed of diagnosis, specificity and sensitivity, reproducibility and case of interpretation. PCR methods are not without their problems however, and there is a need for laboratory procedures to be refined before PCR-based assays are accepted as the tools of choice for the routine detection of protozoan parasites. The application of PCR detection to various parasites is discussed.

Animals↗
PubMed1975

Skin punch biopsies and lymphocytes in the diagnosis of lipidoses.

Skin punch biopsies and buffy coats of white blood cells were examined electron microscopically in patients suffering from a variety of storage diseases. No specific abnormalities could be detected in Gaucher's disease and adreno-leucodystrophy. While characteristic deposits were found in cutaneous nerves in globoid and metachromatic leucodystrophy, this method was deemed inferior to sural nerve biopsy. In gangliosidoses, on the other hand, pathognomonic membranous cytoplasmic bodies were common in axons of cutaneous nerves, and in generalized gangliosidoses marked vacuolation of many other cells was prominent. Specific deposits were found in various cells in skin punch biopsies and in lymphocytes of children suffering from ceroid lipofuscinoses, and in lymphocytes of their parents. This constitutes the easiest diagnostic laboratory procedure in such cases.

Adolescent↗
PubMed1992

Rotavirus detection by dot blot hybridization assay using a non-radioactive synthetic oligodeoxynucleotide probe.

A synthetic oligodeoxynucleotide of 40 nucleotides corresponding to nucleotides 33-72 of the gene coding for the viral protein VP7 of rotavirus, was used as a nucleic acid probe to develop a non-radioactive hybridization method for rotavirus detection. The probe was labelled at the 3' end with biotin-7-dATP. The sensitivity and specificity of the dot blot hybridization assay for rotavirus detection was evaluated with 303 stool specimens. The results indicate that the hybridization assay has a higher sensitivity than both PAGE and EIA. Among the rotavirus strains tested 37 different electropherotypes were found. The results suggest that rotavirus diagnosis by dot hybridization using a non-radioactive probe may become routine laboratory procedure because it is simple, highly specific and very sensitive.

Base Sequence↗
PubMed1993

Acute respiratory illness in the community. Frequency of illness and the agents involved.

Investigations of respiratory illnesses and infections in Tecumseh, Michigan, USA, were carried out in two phases, together covering 11 years. During the second phase, there were 5363 person-years of observation. Respiratory illness rates in both males and females peaked in the 1-2 year age group and fell thereafter. Adult females had more frequent illnesses than adult males; illnesses were less common in working women than in women not working outside the home. Isolation of viruses fell with increasing age; rhinoviruses were the most common isolate. Influenza infection rates, determined serologically, suggested relative sparing of young children from infection with type A (H1N1) and type B. Infection rates were highest in adult age groups for type A (H3N2). The isolation and serological infection rates were used to estimate the extent to which laboratory procedures underestimated the proportion of respiratory illnesses caused by each infectious agent; data from other studies were also used in this estimation. Severity of respiratory illnesses was assessed by the proportion of such illnesses that resulted in consultation of a physician. Rhinoviruses produced the greatest number of consultations. Overall, physician consultations were associated with 25.4% of respiratory illnesses.

Adolescent↗
PubMed2001

Microflow-based automated chemistries: application to protein sequencing.

We describe a microflow-based instrument, consisting of multiple rotary valves, capillary tubing, and miniaturized reaction vessels, for the purpose of performing automated chemical and biochemical reations on a very small scale (i.e. submicroliter volumes). The novelty is that close to 100% of the reaction end products are available in a minimal volume (< or = 5 microL) inside a pressurized microvial for subsequent analysis. This makes the system compatible with capillary HPLC and, in principle, with continuous-flow nanoelectrospray mass spectrometry. Total control of flow path combinations and directions, temperatures, and gas pressures enables precise execution of complex biochemical laboratory procedures. Instrument performance was convincingly demonstrated by partially sequencing 100 fmol of an intact protein using classical Edman chemistry in combination with capillary-bore liquid chromatography. To our knowledge, this is the smallest amount of protein ever reported to be successfully analyzed in this way. Additional applications that merge enzymatic and chemical procedures with high-sensitivity analytical devices can be envisioned in the future.

Chromatography, High Pressure Liquid↗
PubMed2003

Recovery of semivolatile organic compounds during sample preparation: implications for characterization of airborne particulate matter.

Semivolatile compounds present special analytical challenges not met by conventional methods for analysis of ambient particulate matter (PM). Accurate quantification of PM-associated organic compounds requires validation of the laboratory procedures for recovery over a wide volatility and polarity range. To meet these challenges, solutions of n-alkanes (nC12-nC40) and polycyclic aromatic hydrocarbons PAHs (naphthalene to benzo[ghi]perylene) were reduced in volume from a solvent mixture (equal volumes of hexane, dichloromethane and methanol), to examine recovery after reduction in volume. When the extract solution volume reached 0.5 mL the solvent was entirely methanol, and the recovery averaged 60% for n-alkanes nC12-nC25 and PAHs from naphthalene to chrysene. Recovery of higher MW compounds decreased with MW, because of their insolubility in methanol. When the walls of the flasks were washed with 1 mL of equal parts hexane and dichloromethane (to reconstruct the original solvent composition), the recovery of nC18 and higher MW compounds increased dramatically, up to 100% for nC22-nC32 and then slowly decreasing with MW due to insolubility. To examine recovery during extraction of the components of the High Capacity Integrated Gas and Particle Sampler, the same standards were used to spike its denuders and filters. For XAD-4 coated denuders and filters, normalized recovery was >95% after two extractions. Recovery from spiked quartz filters matched the recovery from the coated surfaces for alkanes nC18 and larger and for fluoranthene and larger PAHs. Lower MW compounds evaporated from the quartz filter with the spiking solvent. This careful approach allowed quantification of organics by correcting for volatility- and solubility-related sample preparation losses. This method is illustrated for an ambient sample collected with this sampler during the Texas Air Quality Study 2000.

Air Pollutants↗
PubMed2006

Study of the influence of alcoholic fermentation and distillation on the oxygen-18/oxygen-16 isotope ratio of ethanol.

A laboratory procedure for the analysis of the oxygen-18/oxygen-16 isotope ratios of ethanol derived from sugars and fruit juices by pyrolysis-isotope ratio mass spectrometry (IRMS) has been applied to the study of isotopic fractionation induced by the isotope effects of fermentation and distillation. For both processes, an experimental model has been established to describe and explain the observed fractionation phenomena. It is shown that reproducible results can be obtained when appropriate analytical conditions are used. Moreover, the ability of ethanol to act as a reliable indicator of the (18)O/(16)O ratio of sugars in orange juice (and therefore to be used as an internal reference for detecting water addition) is demonstrated both in theory and in practice.

Alcohols↗
PubMed2000

Optimization of tannin extraction from infant foods.

The design of experiments (DOE) was used in the development of a laboratory procedure for the extraction of tannins from three infant food types comprising different ingredients of vegetable origin and meat. The diversity of vegetables included in the product formulas required the use of DOE to establish parameters that maximize the recovery of tannins using a central composite rotatable design. Once the experimental results from the DOE were obtained, response surface methodology was used to find the best analytical conditions for samples comprising different ingredients. Sample weight was found to be a critical factor in tannin extraction from foods. Different optimal conditions were obtained for samples including soya in the formula.

Infant Food↗
PubMed2000

Physiological and behavioral regulation in two-year-old children with aggressive/destructive behavior problems.

A sample of 99 two-year-old children was selected on the basis of parents' responses to two administrations of the Child Behavior Checklist for two- to three-year-olds. Forty-nine of these children displayed symptoms of aggressive/destructive (externalizing) problems that were in the borderline clinical range (labelled "high risk") and 50 children displayed few such symptoms ("low risk"). The children were assessed in a series of laboratory procedures that were intended to be emotionally and behaviorally challenging, during which time heart rate was recorded and behavior was observed. To assess physiological regulation, resting measures of heart period and respiratory sinus arrhythmia (RSA), and heart period change and RSA suppression were derived from these procedures. To assess emotional and behavioral regulation, children's affect and on-task versus types of off-task behaviors were measured. Results indicated that children in the high-risk group did not differ from children in the low-risk group on the resting measure of heart period. Boys displayed lower heart rate than did girls, regardless of risk group. However, boys in the low-risk group differed from boys in the high-risk group in terms of resting measures of RSA. Children in the high-risk group did display significantly and consistently lower RSA suppression (physiological regulation) during the challenging situations than did the children in the low-risk group. High-risk children displayed more negative affect and dysregulated emotion regulation behaviors than did the low risk children. These findings are discussed in terms of the development of behavioral and emotional regulation that underlie adaptive versus maladaptive behavior.

Aggression↗
PubMed2000

Regional variation in physician practice pattern: an examination of technical and cost efficiency for treating sinusitis.

OBJECTIVE: An examination of the physician efficiency and resulting cost patterns by region. DATA SOURCES: Virginia Medicaid sinusitis related claims for 1993 were aggregated to physician level (n = 178), and Area Resources File for 1993 was used to identify regions for evaluation. STUDY DESIGN: The best practice performance in the usage of five resources (i.e., primary care physician visits, referral services, emergency room visits, prescriptions, laboratory tests) was identified using Data Envelopment Analysis (DEA). Five regions in Virginia were identified according to regional planning to evaluate the variation in efficiency across these regions. PRINCIPAL FINDINGS: Inefficient physicians consumed significantly more resources and were 48% more costly than efficient physicians. Substantial regional variation was found and mainly attributed to the differences in use of prescriptions and laboratory procedures. Urban-rural discrepancy may explain part of the variation. CONCLUSIONS: As this study reveals the existence of substantial variation in physician efficiency, actions should be taken to minimize the variation that is more affected by personal and structural factors. For example, information on efficient use of resources and corresponding patient outcomes can be disseminated to the attending physicians. Educational workshops can be conducted to allow sharing of experience between efficient and inefficient physicians. Efforts should also be directed to help inefficient physicians to adhere to practice guidelines.

Benchmarking↗