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T O Oei

Publications and source records attributed to T O Oei.

18 recordsLinked to original sources

Routine serum magnesium determination: a contemporary clinical imperative.

Identification of hypomagnesaemia or hypermagnesaemia is presently the most expeditious method of clinically identifying perturbations in Mg metabolism. Clinicians may overlook as much as 90% of clinical hypomagnesaemia and hypermagnesaemia when serum Mg is determined on order versus on a routine basis. Routine serum Mg determination will facilitate management of digitalis toxicity in patients who are not currently identified as being hypomagnesaemic as well as preventing the occurrence of refractory K repletion. In our opinion routine serum Mg determination represents a clinical need which has not been addressed to date.

Animals

Lack of improved growth outcome related to nonnutritive sucking in very low birth weight premature infants fed a controlled nutrient intake: a randomized prospective study.

The effect of nonnutritive sucking during gavage feeding on nutritional outcome and gastrointestinal transit time was evaluated in 18 premature appropriate for gestational age infants whose birth weights were less than or equal to 1,400 g and gestational ages were less than or equal to 30 weeks. Infants were randomized to a treatment (nonnutritive sucking infants received a pacifier for 30 minutes with each feeding, 12 times per day until they reached a weight of 1,500 g, eight times per day thereafter) or control (no pacifier) group. The nine nonnutritive sucking (five girls, four boys) and nine control (five girls, four boys) infants were treated for 14 days. Infants were without medical complications and were fed a single premature formula by intermittent gastric gavage at exactly 120 kcal/kg/d throughout the study period. Weight gain, linear growth, subscapular and triceps skinfold, and arm circumference accretions were assessed weekly. Serum proteins (albumin, prealbumin, retinol-binding protein, and transferrin) were measured weekly. Gastrointestinal transit times were measured weekly using carmine red markers. In contrast to previous studies, these data indicate no apparent effect of nonnutritive sucking on growth outcome, serum proteins, or gastrointestinal transit time in growing, very low birth weight infants when nutrient intake was controlled. In a subgroup of eight boys (four nonnutritive sucking, four control), energy and fat excretions were determined from 72-hour fecal collections and energy expenditure was estimated from six-hour cumulative heart rate measurements. Neither excretion of fat and calories nor estimated energy expenditure was affected significantly by nonnutritive sucking in this subgroup of baby boys. Fat excretion correlated well (r = .987) with energy excretion.

Energy Metabolism

An enzyme immunoassay procedure for cancer antigen 125 evaluated.

The performance of a new enzyme immunoassay (EIA) procedure (Abbott Labs.) for cancer antigen 125 (CA 125) met or exceeded the manufacturer's claims for all analytical variables examined. Overall correlation with results obtained with a radioimmunoassay (RIA) were good. However, near the decision thresholds typically chosen to define a positive result for ovarian carcinoma, EIA results were 10 to 20 arbitrary units/mL less than the RIA results. At specific decision thresholds, therefore, the sensitivities and specificities of the EIA and RIA procedure differed. Adjusting the decision thresholds gave a similar optimum efficiency for each procedure: EIA, 82.9% (decision threshold, 35 units/mL); RIA, 83.4% (decision threshold, 54 units/mL). Receiver-operating characteristic curves showed that the two procedures' ability to distinguish patients with active ovarian carcinoma from those with disease in remission was the same.

Antigens, Tumor-Associated, Carbohydrate

An alternative method for assaying cerebrospinal fluid protein in the presence of methotrexate.

Therapeutic concentrations of methotrexate can cause significant positive interference in cerebrospinal fluid (CSF) protein values when assayed in the Du Pont aca. Conversely, our modified turbidimetric method, in which trichloroacetic acid (TCA) plus a sample blank containing dilute hydrochloric acid is used in place of TCA, exhibits little or no interference from methotrexate. This was verified by assaying solutions that contained a constant amount of protein (approximately 430 mg/L) and various amounts of methotrexate (0.0-2.3 x 10(-4) mol/L) by both the Du Pont aca and the manual turbidimetric method. As expected, the aca results showed increasing protein values with increasing methotrexate, whereas the manual method gave results approximating the expected protein value irrespective of the methotrexate concentration.

Cerebrospinal Fluid Proteins

Radioimmunoassay for arylsulfatase A in urine.

Purified arylsulfatase A (EC 3.1.6.1) from human urine was radioiodinated under conditions that caused no significant loss of antigenic activity. We used this labeled arylsulfatase A (specific radioactivity 4-7.5 Ci/g) together with nonlabeled enzyme and rabbit antiserum produced against homogeneous enzyme to develop a radioimmunoassay for arylsulfatase A in urine. A solid-phase, second-antibody technique (Immunobead Second Antibody; Bio-Rad Laboratories) was used to separate free enzyme from antigen-antibody complexes. The working range of the assay was 0.1-4.0 ng of enzyme; within- and between-assay CVs were around 10%, and the analytical recovery was 105.5% (SD 7.7%). The lower limit of detection was 0.08 ng of arysulfatase A per assay, substantially less than that of typical activity-based assays. Over a wide range of urinary arylsulfatase A activities, results by this method agreed well (r = 0.99) with those obtained by activity assays. We measured the enzyme in urines of 59 healthy volunteers and 92 patients with different diseases, including a group of colorectal cancer cases, to determine whether this could serve as a reliable marker for cancer of the colon; however, urinary excretion of arylsulfatase A by most patients with colon cancer was within normal limits.

Binding, Competitive

Relationship between arterial and venous bicarbonate values.

We determined the clinical efficacy of using the venous CO2 value, as obtained with routine "electrolytes", in acid-base management. Venipuncture samples for venous CO2 content and chloride concentrations were obtained in 336 patients with arterial blood pH, PaO2, PaCO2, and oxygen saturation determinations. The linear correlation between actual calculated arterial HCO3- and the measured venous CO2 was significant (P less than .001). Using venous CO2, chloride, and arterial pH values, we present various prediction equations for estimating arterial HCO3-. We determined the effects of time delay, exposure to air, and acute changes in arterial blood pH and PaCO2 on venous CO2 levels. Venous CO2 determinations should not be substituted for the arterial HCO3 value in the Henderson-Hasselbalch equation to calculate arterial blood pH or PaCO2. Clinically, the venous CO2 value has little direct use, but when venous CO2 content is abnormal, it should alert the clinician to the need for obtaining arterial blood gas and pH values.

Acid-Base Imbalance

Talc in drugs.

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Child

Effect of diet on urinary excretion of VMA, HVA, metanephrine, and total free catecholamine in normal preschool children.

Quantitation of the urinary metabolites of catecholamines, including VMA, HVA, and metanephrines, from six normal preschool children was performed during a normal diet, a restricted diet, and a diet with increased amounts of vanilla, vanillin, and phenolic acids. Ingestion of these substances has been suspected of producing elevated values of urinary catecholamines and their metabolites. Urine was collected on the fourth day of each diet in two consecutive 12-hour aliquots, beginning at 8:00 AM. Statistically significant diurnal variation in excretion of all three metabolites and total free catecholamines (epinephrine, norepinephrine, and dopamine) was demonstrated. Diet did not alter exceretion of total free catecholamines or any of the three metabolites. This study suggests that a three-day restricted diet is not necessary prior to screening children for neuroblastoma when using quantitative assay methods and that all screening tests should be performed on a 24-hour urine sample.

Catecholamines

Evaluation of liquid scintillation counting solutions for radioimmunoassay of hepatitis-associated antigen (HBsAg).

Liquid scintillation counting solutions for radioimmunoassay of hepatitis associated antigen (HBsAg) are evaluated and discussed. Data is also presented which indicates that liquid scintillation counting could be carried out by placing cut-off Ausria-125 test tubes in counting vials containing 10 ml of either Brays, Unogel, or Instagel solutions. The data suggest that Brays was the least effective and Unogel and Instagel were the most effective liquid scintillation counting solutions. This is a fundamental consideration if a laboratory is contemplating an initial investiment in counting equipment. The acquisition of a liquid scintillation counter provides additional capabilities for the clinical laboratory interested in radioisotope measurements. In addition, if a laboratory already has a liquid scintillation counter (Beta counter), the director of the clinical laboratory may elect not to purchase additional counting equipment (gamma counter) since he already has the added advantage of measuring iodine-125 with the Beta counter. The authors propose liquid scintillation (RIA) as an alternative counting system for HBsAg detection in hospital patients and donors.

False Negative Reactions