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Biomedical subjects

J Woo

Publications and source records attributed to J Woo.

At least 379 records · Page 21Linked to original sources
PubMed1981

Levels of angiotensin-converting enzyme in pleural effusion.

The value of determining the angiotensin-converting enzyme (ACE) in serum has been clearly established, particularly in sarcoidosis, but is significance in pleural effusions is practically unknown. In the present study, ACE level was determined in the pleural fluid of 18 hospitalized patients along with the values for total protein, lactic acid dehydrogenase (LDH), complete and differential cell counts and cytology. The ACE level was higher in exudates than in transudates and paralleled closely the total protein level in the pleural fluid. There was no correlation between ACE and LDH levels and either WBC or RBC counts in the effusions. The ACE levels failed to discriminate between benign and malignant diseases or to correlate with any specific etiology for the effusion. There was a significant gradient between ACE levels that were higher in the serum than in the effusion of all nine patients in whom both were measured. The filtration coefficient (ratio of pleural fluid to serum concentration of a protein) of ACE was less than that of total protein and was compatible with ACE penetration in the pleural fluid by a process of diffusion.

Humans↗
PubMed1980

Embolus radiolabelling in a new canine model.

Embolus radiolabelling with 131I fibrinogen was studied in a canine model of internal carotid artery embolization. The dog was chosen as the experimental animal because of its maxillocarotid artery which permits collateral flow round the occlusion and helps to prevent strokes. Clot was prepared by incubating blood at room temperature to inactivate plasminogen activators and then refrigerating it to promote clot retraction. Emboli persisting 48 hours were seen in 80% of animals. Major strokes were not seen when 0.25 to 0.30 cm3 were used. Autoradiography and well counting revealed uptake of isotope. The test, when refined, should provide a tool for the investigation of thromboemboli.

Animals↗
PubMed1980

Prednisolone clearance in renal transplantation.

Although prednisolone is the most common immunosuppressive agent used in renal transplantation, an accurate formulation of the optimal dose regimen remains to be established. A sensitive and precise radioimmunoassay was developed for this purpose. Fifty microliters of 1:20 dilutions of serum or 1:200 dilutions of urine were incubated at room temperature for two hours with 130 pg of 3H-prednisolone (150muCi/microgram) and a rabbit antiserum against prednisolone (1:1,600 dilution). Serial prednisolone clearances (Cp) for ten renal transplant patients representing variable allograft functions were compared with their corresponding creatine clearances (Cer). The data show that renal metabolism of prednisolone is well correlated with Ccr. Increasing (decreasing) Ccr is accompanied by increasing (decreasing) Cp. The availability of an assay for serum prednisolone, together with a knowledge of the ratio between these two clearances, may prove useful for regulating therapy in renal transplant patients.

Dose-Response Relationship, Drug↗
PubMed1980

beta 2-Microglobulin clearance as measured by radioimmunoassay.

We describe a radioimmunoassay for beta 2-microglobulin (beta 2 mu) in serum and urine. We incubated aliquots of diluted samples at room temperature for 1 h with 125I-labeled beta 2 mu and a rabbit antiserum monospecific for human beta 2 mu, and separated the phases by the double-antibody technique. The logit-log transformed dose-response curve was linear in the range 2 to 64 ng, equivalent to 0.5 to 16 mg/L of serum and 0.5 to 320 mg/L of urine. Assay sensitivity was 2.4 ng of beta 2 mu. Validation studies included tests of precision, accuracy, antibody specificity, and parallelism of the dose-response curves for standard and unknown. In a study of 25 normal individuals, serum and urine beta 2 mu ranged from 1.1 to 2.3 mg/L and 40 to 360 micrograms/24 h; the clearance of beta 2 mu was 8 to 130 microL/min. In 21 renal allograft recipients tested one to five weeks after transplantation, serum and urine beta 2 mu ranged from 3.9 to 15.6 mg/L and 7.2 to 611 mg/24 h; beta 2 mu clearance was 0.60 to 33.3 mL/min. Values for both serum and urine correlated well with severity of allograft rejection.

Beta-Globulins↗
PubMed1979

Radioimmunoassay for immunologlobulin G in serum and urine.

We describe a radioimmunoassay for immunoglobulin G (IgG) in serum and urine. Aliquots of diluted samples and 125I-labeled IgG were incubated in antibody-coated tubes at 37 degrees C for 24 h, the supernates were decanted, and the radioactivity in tubes containing the bound fraction was counted. The dose-response curve in the range of 0.4--500 mg/L of urine or 640--40 000 mg/L of serum was linear on logit-log transformation and iterative weighted regression. Assay sensitivity was 10 ng of IgG. Validation studies included testing for precision, accuracy, antibody specificity, and parallelism of the dose-response curves for standard and unknown. In a study of 14 apparently normal individuals, serum IgG = 4.0-10.9 gL, urine IgG = 1.1-4.8 mg/24 h, and IgG clearance = 0.2 X 10(-4) to 4.8 X 10(-4) mL/min. In 20 patients with renal allografts, serum IgG = 15.8-66 g/L, urine IgG - 9.6-626 mg/24 h, and IgG clearance = 9 X 10(-4) to 1.99 X 10(-1) mL/min. IgG values correlated well with severity of renal allograft rejection.

Graft Rejection↗
PubMed1978

Decreased angiotensin-converting enzyme in the adult respiratory distress syndrome.

Using hippuryl-L-histidyl-L-leucine as substrate, serum angiotensin-converting enzyme was measured in 13 patients who had adult respiratory distress syndrome, eight patients with respiratory failure without adult respiratory distress syndrome, and two groups of controls: 24 healthy blood donors and 24 hospitalized patients with a variety of conditions but without respiratory failure or adult respiratory distress syndrome. Serum angiotensin-converting enzyme expressed in units/ml was 14.60 +/- 5.60 for adult respiratory distress syndrome compared with 28.92 +/- 6.60 for the blood donors, 20.76 +/- 5.87 for the patients with respiratory failure without adult respiratory distress syndrome and 20.20 +/- 5.94 in the hospitalized patients without respiratory failure or adult respiratory distress syndrome. These differences were significant, P less than .001 when adult respiratory distress syndrome was tested against the blood donors and P less than .01 against the other two groups. The significance of these findings is not clear, but the possibility is raised that the decrease of angiotensin-converting enzyme in adult respiratory distress syndrome results from a loss of pulmonary endothelial cells, which are known both to produce angiotensin-converting enzyme and to be damaged in adult respiratory distress syndrome.

Adolescent↗
PubMed1978

Radioimmunoassay for urinary albumin.

We describe a rapid, sensitive, and precise radioimmunoassay for urinary albumin (Ualb). Aliquots of diluted urine were incubated at room temperature for 1 h with 125I-labeled albumin and a rabbit antiserum monospecific for human albumin. Phase separation was effected by the double-antibody technique. The dose-response curve as linear in the range of 15.6-10000 ng, equivalent to 4 to 3000 mg/liter of urine. The limit of sensitivity was 16 ng of albumin. The coefficient of assay variation was 4.8%, both at 44 mg/liter and at 1304 mg/liter. A displacement curve obtained with a serially diluted urine sample of high albumin concentration was completely superimposable with the curve for which human albumin was used as a standard. In 26 normal individuals the range for Ualb was 2.2--12.6 mg/24h, and for albumin clearance (Calb, 1.8 x 10(-5)-19.6 x 10(-5) ml/min. After renal homografts in 25 patients, Ualb ranged from 16.9 to 9928 mg/24 h, and Calb from 2.7 x 10(-4) to 1.7 x 10(-1) ml/min. Both increased Ualb and Calb correlated well with the severity of renal homograft rejection.

Albuminuria↗
PubMed1977

Spectrofluorometry of free and protein-bound plasma tryptophan.

We report a rapid, simple, and sensitive spectrofluorometric procedure for total serum or plasma tryptophan. Plasma deproteinization, tryptophan extraction, and pH optimization are all carried out with a buffered cellulose/ethanol reagent. The fluorescence is measured at an emission wavelength of 350 nm, on excitation of 290 nm. Tryptophan fluorescence relative to concentration is linear up to 50 mg/liter. The high precision, evidenced by a between-run coefficient of variation of 3.1%, negates the need for duplicate analysis of samples. Analytical recovery of tryptophan from plasma up to 50 mg/liter is 90-100%. We observed no significant difference between values for tryptophan in serum and plasma from the same individual. Assay of up to 32 samples requires 60 min. Commonly used anti-depressants have no detectable effect on tryptophan determination by this procedure.

Humans↗
PubMed1976

A quality control program for the radioimmunoassay laboratory.

The major problems in applying quality control to radioimmunoassay measurements are (a) nonlinearity of the dose-response curve, and (b) nonuniformity of the residual variance. A logit-log transformation of the dose-response variables combined with an iterative weighted regression analysis appears to overcome most of the difficulties. This technic is particularly helpful when applied to substandard runs where extraneous standard points tend to distort assay results. The authors describe a quality control program that involves recording control values on calendar and histogram formats, monitoring assay variables by charting, and comparing the computer-calculated slope with the graphic plot to reveal "outliers." This program is useful in guiding technologists to locate possible causes for "out-of-limits" runs.

Computers↗
PubMed1975

Lyapunov Redesign of Model Reference Adaptive Control System for long term ventilation of lung.

A lyapunov redesign of Model reference adaptive control system for a long term, automatically regulated, ventilatory system is presented. A fixed resistance-capacitance RC analog lung model is used to generate a desirable (reference response) alveolar pressure. The instantaneous difference in alveolar pressures between the patient and its model is fed to an adaptive controller. The controller is designed to adjust the patient's inflating pressure in such a way as to reduce the instantaneous difference in the alveolar pressures to zero. The adaptive control system described can be implemented provided the patient's alveolar pressure is continuously measurable. Unfortunately, this measurement is impossible to realize; therefore, a method to estimate the continuous alveolar pressure of the patient is to be developed. This estimation is achieved indirectly from the identification process of the patient's respiratory parameter. The same Lyapunov redesign is used in this identification process. Digital simulation of the control of the patient's inflating pressure and the identification process, as well as the simulation of the combined system, were performed. The result has demonstrated the ability of this adaptive system to perform in a fast and stable manner.

Airway Resistance↗
PubMed1975

Partial characterization of C-type particles in a cell line (WR-9) derived from a rat epidermoid carcinoma of spontaneous origin.

A C-type virus continuously released from a cell line (WR-9) derived from a spontaneous epidermoid carcinoma was purified by means of large-scale tissue culture techniques and high-volume zonal centrifuges. With the use of relatively pure virus concentrates, partial characterization of the virus has been accomplished. Up to 60 liters of spent culture medium from relatively low virus-yielding cultures were processed at a time through the Model K ultracentrifuge in order to obtain quantities of virus sufficient for convenient Tween-ether extraction of the major polypeptide (30,000 daltons). This structural protein having group-specific reactivity was purified and isolated by isoelectric-focusing techniques. A UV absorption peak (A280) was found to be coincident with a major peak of radioacticity at pH 8.6, the isoelectric point (pI) for rat virus gs antigen previously reported by other investigators. Because species-specific (gs-1) and cross-reactive (gs-3) determinants coexist on this protein, fractions containing the group-specific antigen were identified on the basis of the mammalian interspecies determinant (gs-3), using antiserum prepared against Tween-ether-disrupted feline leukemia virus. At the same time, reactivity to the gs-1 determinants in identical fractions was observed in complement fixation and gel diffusion assays, using guinea pig antiserum known to contain principally antibodies to rat gs-1 determinants. Presently, the principal source of rat type C viral gs antigen is rat cell line MSB, which continuously releases a rat leukemia virus pseudotype of murine sarcoma virus. The WR-9 rat virus line may be of use in providing an additional source of C-type particles that are capable of yielding good gs reagents.

Animals↗