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Biomedical subjects

N B Smith

Publications and source records attributed to N B Smith.

At least 37 records · Page 2Linked to original sources
PubMed1993

Scintigraphic defecography: quantitative and dynamic assessment of anorectal function.

PURPOSE: Conventional assessment of anorectal function with defecating videoproctography is semiquantitative and the high radiation exposure precludes prolonged or repeated testing. The aim of this study was to develop a dynamic scintigraphic method of assessing anorectal function. METHODS: Fourteen patients with fecal incontinence, 18 patients with chronic constipation, and 8 control subjects were assessed by scintigraphic defecography. This involves introduction of a technetium-99m-radiolabeled artificial stool into the rectum of the subject and acquisition of gamma camera images during evacuation. RESULTS: Mean evacuation rate was 2.8 percent/second in incontinent patients and 0.9 percent/second in constipated patients (P < 0.001). The mean anorectal angles were 136 degrees and 133 degrees, respectively. There were 18 cases of pelvic floor descent and 6 rectoceles. Scintigraphic defecography provides quantitative information on rectal evacuation. Anorectal angle and pelvic floor movement can be examined. The radiation dose to pelvic organs is significantly less than with videoproctography. CONCLUSION: We believe that scintigraphic defecography is the investigation of choice for objective and dynamic assessment of anorectal function.

Adult↗
PubMed1991

A teratologic evaluation of continuous-wave, daily ultrasound exposure in unanesthetized pregnant rats.

Pregnant Sprague-Dawley rats were trained to remain immobile when placed in water in an ultrasound exposure tank and exposed to 0, 0.1, 2.0, or 30.0 W/cm2 ISPTA (spatial peak, temporal average), 3.0-MHz continuous wave (cw) ultrasound on embryonic (E) days 4-19 for approximately 15 min/day. On E20 fetuses were removed; weighed; examined for external, skeletal, and visceral malformations; and uteri were examined for resorptions. Analyses revealed no increase in pre-implantation loss and no effects on maternal body weight, food, or water consumption. No increase in skeletal or visceral malformations was found, in fact exposed groups had a lower incidence of defects than controls. A significant increase in resorptions in the lowest exposure group (0.1 W/cm2) was obtained, but the effect was isolated, non-dose dependent and not credible as a treatment-related effect. No reduction in fetal weight was obtained, in fact the lowest (0.1-W/cm2) and middle (2.0-W/cm2) exposure level groups weighed slightly more than controls. The immobility procedure succeeded in avoiding anesthetization or forced restraint of the dams, thereby eliminating these factors as potential confounders. The results demonstrated that in unanesthetized, unrestrained rats in utero exposure to incident intensities of ultrasound of up to 30.0 W/cm2 cw ultrasound (or estimated internal exposures of 4-21 W/cm2, depending on body orientation to the incident beam) produced no evidence of embryotoxicity based on fetal necropsy data.

Analysis of Variance↗
PubMed1991

Efficient extraction of basic, neutral, and weakly acidic drugs from plasma for analysis by gas chromatography-mass spectrometry.

We describe a method for efficiently extracting basic, neutral, and weakly acidic drugs from plasma for toxicological analysis by gas chromatography-mass spectrometry (GC/MS). The 2-mL plasma sample is diluted with an equal volume of saturated NaCl containing triethylamine, 10 mmol/L, and then extracted twice with 4 mL of an equivolume solution of dichloromethane/acetone. The organic (top) phases are combined, then mixed with 1 mL of water, 200 mg of NaHCO3, and 100 microliters of acetic anhydride. This mixture is then heated at 75 degrees C until the solvents have boiled off and aqueous acetylation is complete (less than 30 min). After addition of 1 mL of water and 2 g of NaCl, the sample is extracted twice with 2 mL of dichloromethane/acetone (2/1 by vol). The combined extracts are dried and then subjected to thin-layer chromatography on a blank Toxi-Lab Toxi-A chromatogram with 1-chlorobutane as the developing solvent (about 6 min). After the lipids have migrated with the mobile phase, the drugs are eluted from the origin with acetone/triethylamine (29/1 by vol), evaporated, and reconstituted in injection solvent. With this procedure drugs are recovered relatively quickly (less than 2 h) and the GC/MS total ion chromatograms are very clean. Studies with 13 basic, neutral, and weakly acidic drugs showed that all except theophylline were extracted with recoveries of at least 75%.

Acetylation↗
PubMed1989

Versatile, efficient system for extracting drugs from urine for gas chromatographic/mass spectrometric analysis.

This is a method for efficiently extracting a wide variety of drugs from urine for toxicological analysis by gas chromatography/mass spectrometry. Before extraction, the urine sample is acetylated, diluted with an equal volume of water, and saturated with NaCl. This solution is then mixed with an equal volume of dichloromethane/acetone (2:1 by vol). The organic (top) phase is aspirated and evaporated, and the residue is redissolved in a suitable solvent for injection or further derivatization. This procedure is suitable for all drugs except carboxylate-containing drugs, which may be isolated by replacing the acetylation step with acidification of the urine to pH 2. Studies with 16 drugs containing amino, amide, alcoholic hydroxyl, phenolic hydroxyl, carboxylate groups, or combinations thereof, showed that all drugs except theophylline and benzoylecgonine were extracted with analytical recoveries ranging from 70% to 100%.

Acetylation↗
PubMed1987

Cutaneous manifestations of Corynebacterium group JK sepsis.

A 14-year-old boy developed group JK corynebacteria sepsis and a generalized erythematous macular and papular skin eruption following chemotherapy for relapse of acute lymphocytic leukemia. Lesional skin biopsy demonstrated effacement of eccrine glands by numerous pleomorphic gram-positive bacilli, morphologically consistent with Corynebacterium and confirmed by culture. This is the first known report documenting the generalized skin manifestations and histopathologic features associated with Corynebacterium sepsis.

Adolescent↗
PubMed1986

The organization of a 24-hour blood alcohols (volatiles) screening service in a hospital laboratory.

We describe the organization that evolved in the Clinical Biochemistry Department of a tertiary-care hospital for handling blood (serum) alcohol (volatiles) determinations. We use a microprocessor-controlled capillary gas chromatography system which will detect and quantitate methanol, ethanol, isopropanol and acetone. Minimal operator intervention is required, allowing operation of the system 24 hours each day, thus permitting timely detection of these volatiles. A Specimen Trace Card has been devised to document continuity of sample handling from the time of blood collection until completion of the analysis. This has proved of value when laboratory records are used for legal purposes.

1-Propanol↗
PubMed1984

Determination of volatile alcohols and acetone in serum by non-polar capillary gas chromatography after direct sample injection.

In this method for detection and quantification of volatile alcohols by capillary gas chromatography, the serum sample is deproteinized, then directly injected into the gas chromatograph with 1-propanol as the internal standard. The capillary column is a 30-m bonded methylsilicone-coated, fused-silica column. With helium as the carrier gas, the injector inlet is set at a split ratio of 1/30 and the average linear velocity in the column is 25 cm/s. Injector and flame-ionization detector temperatures are 280 degrees C, oven temperature 35 degrees C. Chromatography time is less than 3 min.

Acetone↗
PubMed1983

Gas-liquid chromatography of cholesteryl esters on non-polar and polar capillary columns following on-column injection.

Capillary gas chromatography of cholesteryl esters following on-column injection was investigated in fused silica columns coated with a non-polar "bonded" liquid phase (DB-1) or a polar liquid phase (SP2330). The 15-m DB-1 column (0.3 mm I.D.) completely resolved the esters on the basis of carbon number, and further partially separated the saturated esters from unsaturated esters. The polar column system consisted of a 10-m SP2330 column (0.25 mm I.D.) butt-connected to a 60-cm empty deactivated wide-bore (0.3 mm I.D.) capillary column into which the sample was injected. This system completely separated the cholesteryl esters according to degree of unsaturation. The lower limits of sensitivity of the columns were about ten-fold lower than that previous obtainable with splitless injection. The lower limits for the DB-1 and SP2330 columns were about 500 and 1500 pg respectively. Thus these columns can be used for the analysis of cholesteryl esters from the smallest of biological or cell culture samples.

Animals↗