Selection of mutant Chinese hamster ovary cells altered glycoproteins by means of tritiated fucose suicide

Mutant Chinese hamster ovary cells altered in glycoproteins have been isolated by selecting for ability to survive exposure to [6-3H]fucose. Mutagenized wild-type cells were permitted to incorporate [3H]fucose to approximately 1 cpm of trichloroacetic acid-insoluble radioactivity per cell and then frozen for several days to accumulate radiation damage. The overall viability of the population was reduced by 5- to 50-fold. Four consecutive selection cycles were carried out. The surviving cells were screened by replica plating-fluorography for clones showing decreased incorporation of fucose into trichloroacetic acid-insoluble macromolecules. Considerable enrichment for cells deficient in fucose uptake or incorporation into proteins (or both) was found in populations surviving the later selection cycles. Two mutant clones isolated after the fourth selection cycle had the same doubling time as the wild type, but contained only 30 to 40% as much fucose bound to proteins as the wild type. Sialic acid contents of the mutants and the wild type were similar. The mutants differed quantitatively and qualitatively from the wild type and from each other with respect to total glycoprotein profiles as visualized by sodium dodecyl sulfate gel electrophoresis. Differences were also found in resistances to cytotoxicity of lectins such as concanavalin A and wheat germ agglutinin.

Analytical investigations closer to the patient

Do-it-yourself bioanalytical equipment that requires no analytical skill to operate is currently available for use in intensive care units, operating suites, side wards, health centres, clinics, general practitioners' surgeries, etc. Agreement is needed between the laboratory consultant and doctors and others using laboratory-type equipment and reagents in near-bedside analyses for diagnosis, clinical management, or health screening of their patients. Choice and safety of method procedure, operator training and accountability, quality control and assessment, maintenance, safety and future development of do-it-yourself equipment must be considered.

Estrone sulfate and dehydroepiandrosterone sulfate concentrations in normal subjects and men with cirrhosis

Circulation levels of estrone sulfate (E1S) and dehydroepiandrosterone sulfate (DHAS) have been measured in plasma using a radioimmunoassay for estrone and dehydroepiandrosterone following extraction and hydrolysis of the sulfate. The mean +/- SE concentrations of E1S and DHAS in normal men were 458 +/- 25 pg/ml and 1.45 +/- 0.19 micrograms/ml, respectively. In normal women the values for days 5-7 of the cycle were 880 +/- 117 pg/ml and 1.25 +/- 0.12 micrograms/ml which were not different than the values for days 20-22 of 1195 +/- 176 pg/ml and 1.58 +/- 0.29 micrograms/ml. The mean values in post-menopausal women were 250 +/- 33 pg/ml and 0.47 +/- 0.07 micrograms/ml, both lower than the values in young women. In a group of cirrhotic men the mean values were 325 +/- 55 pg/ml and 0.38 +/- 0.12 micrograms/ml, both significantly lower than the normal values. This suggests a defect in sulfurylation in men with hepatic cirrhosis.

Nocodazole action on tubulin assembly, axonal ultrastructure and fast axoplasmic transport

The action of a synthetic antitubulin agent, nocodazole, on tubulin self-assembly, preformed microtubules, fast axoplasmic transport and axonal ultrastructure was studied. Nocodazole completely blocks the self-assembly of tubulin containing or lacking associated proteins. This inhibition is readily reversible. At similar concentrations, nocodazole also depolymerizes preformed microtubules in vitro. Fast axoplasmic transport in cat vagus nerve is disrupted by bathing the nerve fivers in a medium containing 10 micrometer nocodazole for periods of 2.5 hr or longer. A 4-hr exposure results in extensive inhibition. The nocodazole action on fast axoplasmic transport appears to be reversible but with a high degree of variability. After 2.5 hr of exposure to 10 micrometers nocodazole, there is a slight decrease in axonal microtubules and an increase in 10 nm neurofilaments. A 4 hr exposure results in a marked reduction in microtubules. These results suggest that nocodazole has a mode of action similar to other antimicrotubule agents.

Unusual aspects of atrial myxoma

Cardiac myxomas are infrequently encountered lesions. Certain aspects of these tumors are unusual and include right atrial location, calcification, valve destruction, hematologic abnormalities, occurrence in children, and familial occurrence. A 12-year-old girl manifesting all of these unusual aspects of myxoma is described and each of the unusual aspects is discussed.

Noradrenaline to adrenaline ratio in amniotic fluid as an index of fetal maturity

Amniotic fluid lecithin to sphingomyelin ratio (L/S) and adrenaline concentration, noradrenaline concentration, and noradrenaline to adrenaline ratio (NA/A) were measured in 50 normal women late in pregnancy. Between gestation weeks 37 and 43 the maturity-linked increase in L/S ratio was accompanied by similar increases in NA/A ratio and noradrenaline but by decreases in adrenaline concentration. Although the amniotic fluid NA/A ratio reflects fetal sympathetic nervous system development rather than pulmonary development as mirrored by the L/S ratio, a high correlation existed between log NA/A and L/S, indicating that the NA/A ratio could provide a further index of fetal maturity.

The case for laboratory aides in district clinical chemistry departments

A case of need is made out for the general introduction into district clinical chemistry departments of the existing experimental grade of laboratory aide or assistant. Subject to direct supervision by qualified personnel the aide has a useful role to fulfil. Important advantages to staff and patients accrue from the employment of this semiskilled laboratory worker.

Effects of testosterone and dihydrotestosterone on spermatogenesis, rete testis fluid, and peripheral androgen levels in hypophysectomized rats

To compare the effects of testosterone (T) and dihydrotestosterone (DHT) on the maintenance and the restoration of spermatogenesis, hypophysectomized (APX) rats were treated daily for 35 days with 0.5 mg of T propionate (TP) or DHT propionate (DHTP) beginning 5 or 33 days after hypophysectomy. In the maintenance experiment, the weights of the testes and the number of early spermatids were significantly lower in DHTP-than in TP-treated animals, while late spermatids were present only in rats treated with TP. In the restoration experiment, TP increased testicular weight and the number of germinal cells, whereas DHTP had very little effect on the testis. In an attempt to explain these findings, we measured androgen levels in the rete testis fluid (RTF) and peripheral plasma of APX rats treated with TP or DHTP. The concentration of T in the RTF of TP-treated rats was nearly 3-fold higher than the level of DHT in the RTF of animals given DHTP. Plasma T levels measured 1/2, 2, 4, and 24 hours after the last of three daily injections of TP were considerably higher than were the corresponding plasma DHT levels in animals given DHTP. In animals treated with free steroids, peripheral androgen levels between 1/2 and 4 hours after the last injection were much higher in rats given T than in those given DHT, but thereafter this difference disappeared. We conclude that the difference in the ability of subcutaneously injected TP and DHTP to maintain and to restore spermatogenesis in APX rats was due to a difference in androgen levels in the testes of these animals.

Radioimmunoassay kits for thyroid hormones

Characteristics of the T4 and T3 radioimmunoassay kits that are commercially available in the UK are described. Useful comparative data and criticism are given about many of these kits. Some unacceptable variation in accuracy is demonstrated.

Serum triiodothyronine determination in clinical use

Two radioimmunassays for the determination of serum triiodothyronine (T3) were developed. The assay of T3 in unextracted serum had several advantages over the assay on extracted serum and was chosen for the routine determination of T3 in serum from 117 patients requiring assessment of their thyroid status. In 53 subjects considered retrospectively not to have thyroid dysfunction nor to have been on steroid contraceptives or therapy, the pooled mean serum T3 concentration was 1-92 (actual range 0-88-2-62) nmol/l. A significant inverse relationship was observed between the serum T3 level and the age of the subject. Serum total T3 levels discriminate clearly between hypo-,eu- and hyperthyroid patients and provide a rather more sensitive index of hyperthyroid function than total serum T4. In the face of normal serum T4 the T3 level was depressed in five patients with marked hypoproteinaemia and elevated in two patients taking heroin.

The use of the amniotic fluid lecithin/sphingomyelin (L/S) ratio, creatinine concentration and nile blue sulphate tests, individually and in combination, in the assessment of fetal lung maturity

The lecithin-sphingomyelin (LS) ratio is a good, but not absolute, test of fetal lung maturity. A total of 373 infants was delivered within 72 hours of amniotic fluid collection for assessment of the L/S ratio. Five of 43 infants (11-6 per cent) with an L/S ratio of 2-2 or less developed the respiratory distress syndrome (RDS), whereas only one of 320 infants (0-31 per cent) with a higher L/S ratio developed RDS. The risk of RDS could be further defined by using the creatinine concentration (critical value 19 mg/1) and the Nile blue sulphate test (critical value 4 per cent) in combination with the L/S ratio. All three tests were performed in 320 pregnancies and in each instance delivery took place within 72 hours. When all three test results were low, 3 of 5 infants (60 per cent) developed RDS, whereas when all three results were high, none of 175 infants developed RDS. When one or two results were low, 2 of 140 infants (1-4 per cent) developed RDS.

Noninvasive cardiac evaluation (NICE) of intracardiac shunts using inhaled radioactive carbon dioxide

A totally new, noninvasive technique is presented for the detection and analysis of left-to-right cardiac shunts. Five millicuries of oxygen 15-labeled carbon dioxide is administered by a single-breath inhalation technique. The resultant lung washout curve accurately reflects the presence or absence of a shunt. The quantitative studies are promising, but the method must be compared with standard techniques in a statistically significant series. This work is in progress.