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Biomedical subjects

J C Nelson

Publications and source records attributed to J C Nelson.

At least 217 records · Page 12Linked to original sources
PubMed1978

Detection of factor XIIIa (active fibrin-stabilizing factor) in normal plasma.

Factor XIIIa (active fibrin-stabilizing factor) generated in heat-defibrinated plasma by the addition of thrombin can be measured by 14C-putrescine incorporation into casein. Modification of this assay be substituting 3H-putrescine of high specific activity as the donor amine permits measurement of amine incorporation by plasma even in the absence of added thrombin. Incorporation is calcium dependent, inhibited by iodoacetamide, and absent from congenital factor XIII-deficient plasma and from normal platelets. The transamidating activity detected by radioenzymatic assay catalyzed the formation of gamma-gamma dimers and alpha polymers of fibrin and was thus biologically functional. This fibrin cross-linking activity was absent from factor XIII-deficient plasma. These experiments show (1) some factor XIII is present in plasma as factor XIIIa; (2) this factor XIIIa can cross-link fibrin and thus has biologic activity as well; and (3) this activity is not present in factor XIII-deficient plasma. Factor XIIIa in normal plasma is possibly activated in vivo, perhaps by circulating thrombin, factor Xa, or other proteolytic enzymes.

Blood Platelets↗
PubMed1978

Measurement of three aminoglycosiee antibiotics with a single radioimmunoassay system.

A versatile radioimmunoassay procedure has been developed to specifically assay gentamicin, tobramycin, or amikacin. Iodinated derivatives of these three antibiotics were prepared by a modified Bolton and Hunter procedure. A single reagent system composed of a pool of three very specific antisera was used in the procedure. The antisera combination did not alter the specificity of the procedure. Validation of the assay of the three antibiotics included studies of parallelism, accuracy, precision, reproducibility, and method comparison with other radioimmunoassay procedures involving single antiserum systems. We discuss the application of this multiple assay capability to other procedures involving use of immunochemicals.

Amikacin↗
PubMed1976

Birth sequence in mice.

Succession of deliveries at parturition was determined in mice following a marker injection in utero. The data failed to refute the hypothesis of a random birth order, as delivery from either uterine horn was found to be unpredictable. In addition, significantly more females delivered the first pup from the right uterine horn, supporting the concept of a "physiological dominance" for the right side of the mouse reproductive tract.

Animals↗
PubMed1975

Amikacin: a rapid and sensitive radioimmunoassay.

A rapid, sensitive, and specific radioimmunoassay has been developed for the measurement of amikacin, a new semisynthetic aminoglycoside antibiotic. Antisera were produced by immunizing rabbits with amikacin conjugated to porcine thyroglobulin. Sera were screened for amikacin antibodies with (3)H-labeled amikacin. Free and bound radioactivity were separated by the second antibody method. As little as 5 ng of the antibiotic can be measured in serum, cerebrospinal fluid, and urine. The standard curve is unaffected by pH (5-11), ionic strength (0.01 M to 0.3 M), MgCl(2) or CaCl(2) (1 to 8 mM/liter), or urea (10-300 mg/100 ml). The antibodies raised to amikacin are not able to distinguish between kanamycin and amikacin. The cross reactivity of all other antibiotics tested was <0.1%. Co-incubation of first and second antibody allows for a 30-min incubation period, making the assay useful for stat determinations. The standard curve is linear on a logit-log plot, allowing for rapid computer analysis of the standard curve, interpolation of sample values, and quality-control monitoring.

Amikacin↗
PubMed1975

A remission of goitrous hypothyroidism during pregnancy.

A 21-yr-old female with a diffuse goiter, hypothyroidism, elevated thyroid autoantibodies, and chronic lymphocytic thyroiditis on needle biopsy, was subsequently nongoitrous and euthyroid with normal antibody titers during pregnancy. Following deliver, the goiter reappeared, autoantibody titers rose and hypothyroidism recurred. Chronic lymphocytic thyroiditis may undergo spontaneous remission during pregnancy.

Adult↗
PubMed1975

The diagnosis of Hashimoto's thyroiditis.

Computer methods were used to estimate the usefulness of several clinical signs and laboratory tests in the diagnosis of chronic lymphocytic (Hashimoto's) thyroiditis. Information was drawn from the records of 217 patients with this disease seen at two hospitals in Southern California. The parameters studied included the physical characteristics of the thyroid gland; the appearance of the radioisotope thyroid scan; the response to a perchlorate discharge test; the serum antithyroglobulin antibody titer; the serum TSH concentration measured by radioimmunoassay; the thyroid radioiodine uptake response to exogenous TSH stimulation; and the serum PBI-T4I difference. Of the above, the PBI-T4I difference was deleted, being of limited value. The TSH stimulation test and serum TSH measurement were considered as alternative ways to evaluate thyroid reserve. Therefore, five diagnostic markers remained, all useful but not definitive. Computer and rule-of-thumb methods (two or more of the five markers positive) were tested for successful diagnosis of 145 patients with Hashimoto's thyroiditis proven by pathological examination of biopsied tissue; 23 of these were patients not used in the original pool of data. As a rule of thumb, it was found that Hashimoto's thyroiditis is the likely diagnosis if two or more out of the five useful markers are in its favor. For best results, four and preferably all of the five criteria should be tested. If this is done, the expected diagnostic accuracy for patients with Hashimoto's disease is by the rule-of-thumb method 67% correct, 21% indecisive, and 12% false negative; by computer methods it is 88% correct, 4% indecisive, and 8% false negative. By each method the number of false positive diagnoses was equivalent to 25% of the total number of patients with this disease. The false positive results nearly all occurred in patients with goiter associated with a defect in thyroid hormone synthesis.

Biopsy↗
PubMed1975

Serum diiodotyrosine.

Serum diiodotyrosine (DIT) was measured by radioimmunoassay in healthy subjects patients with thyroid disease and a variety of laboratorty animals. Ninety-two healthy adults had a mean level of 101 ng/100 ml. There was no sex difference in DIT levels but DIT fell with aging. There was no change with short term oral SSKI administration. Athyrotic subjects had measurable but reduced levels (mean = 52 ng/100 ml). Hyperthyroid subjects had levels slightly, but not significantly, higher than controls (mean = 149 ng/100 ml). Treatment of hyperthyroidism was followed by a small but significant fall in DIT levels, but there was no change in DIT levels with thyroid hormone therapy of hypothyroidism. A large species variation in serum DIT levels was found among laboratory animals with mean levels ranging from 17 ng/100 ml in mice to 428 ng/100 ml in dogs.

Adenoma↗
PubMed1974

A multiple ligand-binding radioimmunoassay of diiodotyrosine.

A radioimmunoassay has been developed for the measurement of 3,5-diiodo-L-tyrosine (DIT) in serum. DIT was coupled to porcine thyroglobulin (PTg) with a molar ratio of 205:1. Rabbits were immunized with 1 mg of immunogen emulsified in complete Freund's adjuvant. Sera were screened for their ability to bind trace amounts of [125I]DIT. A serum that bound 40% of the tracer at a final dilution of 1:1,750 was used in the assay. Assay specificity was improved by the use of thyroxine (T4)-binding globulin as a second ligand-binding protein to decrease T4 and triiodothyronine (T3) cross-reactivity with the antibody. Double antibody and polyethylene glycol radioimmunoassays were compared. DIT present in the second antiserum shifted the double antibody assay standard curve and altered estimates of assay specificity and assay sensitivity. By using the polyethylene glycol system and butanol:ethanol extracts of serum, DIT was measured in human serum. In 35 apparently healthy young adult controls DIT levels averaged 156 ng/100 ml. Random DIT levels averaged 158 ng/100 ml in 11 untreated hyperthyroid patients and 84 ng/100 ml in 15 untreated primary hypothyroid patients. No diurnal pattern in DIT levels could be demonstrated. Thyroid-stimulating hormone administration led to a variable but small rise in DIT levels, but short term T3 suppression was not associated with a measurable fall in DIT concentrations. Paired serum samples from the carotid artery and thyroid vein of 10 euthyroid goiter patients and one patient with a toxic solitary adenoma all showed a positive transthyroidal gradient indicating the thyroidal release of DIT in each patient. Measurable DIT levels of 45, 47, 68, and 80 ng/100 ml, respectively, were found in four fasting athyrotic patients indicating that the thyroid is not the only source of serum DIT.

Adult↗