The relationship between guanosine tetraphosphate, polysomes and RNA synthesis in amino acid starved Escherichia coli

A relA+ strain of E. coli with four amino acid requirements was starved separately for each amino acid, after which the levels of polysomes, guanosine-5'-diphosphate-3'-diphosphate and the residual net synthesis of RNA were determined. The polysome level and guanosine-5'-diphosphate-3'-diphosphate production were coordinately affected by starvation for the different amino acids, whereas no correlation was found between these two parameters and residual RNA synthesis. The main conclusion stemming from these results is that guanosine-5'-diphosphate-3'-diphosphate cannot act as the sole effector molecule in stringent control of RNA synthesis.

The effects of trimethoprim and erythromycin on polysome metabolism in Escherichia coli

Trimethoprim and erythromycin were shown to have different overall effects on in vivo polysome metabolism in Escherichia coli. In a rel A+-rel A pair of strains, trimethoprim treatment induces a reduction of polysome level to a variable extent, similarly to aminoacyl tRNA deprivation of cells, but persisting polysomes remain dynamic structures in a state of continual turnover. In contrast, erythromycin stabilizes polysome level to a high value in either kind of strain, but maintained polysomes appear as "frozen" structures unable to undergo ribosome translocation.

Thyroglobulin biosynthesis in a larval (ammocoete) and adult freshwater lamprey (Lampetra planeri Bl.)

1. The biosynthesis of 18-19S thyroglobulin has been studied in a larval and adult freshwater lamprey (Lampetra planeri Bl.). 2. In vivo and in vitro experiments have been performed by injecting into the coelomic cavity or by incubating branchial region labeled constituents of Tg of higher vertebrates (125I, [3H]leucine and various [3H]carbohydrates). 3. Larvae (ammocoetes) and adults incorporate all labels into thyroglobulin (18-19S Tg), containing a small proportion of labeled T3 and T4, as identified by paper chromatography, and very minute amounts of stable iodine. 4. In adults, the biosynthesis of 18-19S Tg proceeds much more rapidly and the labels are incorporated in higher percentage than in larvae. 5. The demonstration of the biosynthesis of the specific thyroid protein, 18-19S Tg, in larvae indicates that the biochemical mechanism of hormonogenesis is present in larval endostyle before the morphological differentiation of thyroid cells and follicles occurring during metamorphosis. 6. Some 18-19S Tg is apparently stored in the endostyle.

Increase in amylase clearance in relation to creatinin clearance during acute pancreatitis

Renal amylase clearance in relation to creatinin clearance (Cam/Ccr) was determined for 20 patients suffering from acute pancreatitis (AP). For each of them, the diagnosis rested upon operative or laparoscopic observation of characteristic anatomical or histological lesions. The average clearance relationship in these patients reached 16 +/- SEM 3.8%. These results were significantly higher than those obtained from 132 patients who had been hospitalized for other medical or surgical diseases, as well as from 51 test patients (p less than 0.001). The authors stressed the diagnostic importance of this test, in particular in the presence of a normal amylasemia level.

[Carcinoid heart disease secondary to a tumor of the small intestine. Apropos of a case with associated tricuspid and pulmonary insufficiency]

The authors report a case of carcinoid heart disease secondary to a tumour of the small bowel with liver metastases. There were severe lesions of the endocardium on the right side of the heart, with gross pulmonary and tricuspid incompetence. The left side of the heart did not escape but the fibrous plaques were limited to the papillary muscle of the mitral valve, and had no effect upon the haemodynamics. The pathogenesis of the strange cardiac lesion may be partly explained in terms of the toxicity to the endothelium of bradykinin. In spite of the serious nature of the valvular damage is it right to consider surgical correction, bearing in mind the fact that the prognosis of carcinoid syndrome is still very poor despite treatment?

Effect of hyper- and hypothyroidism on platelet monoamine oxidase activity and serotonin metabolism

We evaluated platelet monoamine oxidase (MAO) activity in 13 hyperthyroid and 9 hypothyroid patients. The platelet MAO activity of these patients did not differ from that of age- and sex-matched euthyroid control subjects. Nineteen hyperthyroid and twelve hypothyroid subjects had serum serotonin concentrations similar to those of age- and sex-matched euthyroid control subjects. We also determined the urinary excretion of 5-hydroxy-indoleacetic acid (5-HlAA), serotonin, tryptamine, and tyramine in five hyperthyroid and four hypothyroid subjects. Two hyperthyroid patients had increased tyramine excretion; one of these patients also had increased tryptamine excretion. Three hypothyroid patients and one hyperthyroid patients had slightly decreased serotonin excretion. Both the hyper- and the hypothyroid subjects had normal urinary 5-HIAA excretion. There was no relationship between platelet MAO activity and monoamine excretion in the patients with thyroid dysfunction. We conclude that there is no systematic change in platelet MAO activity or serum serotonin concentration in patients with hyper- or hypothyroidism.

The two triiodothyronines (T3 and rT3). Thyroid biosynthesis of T3 and rT3 and peripheral metabolism of thyroxine (author's transl)

Thirty per cent of the iodine in thyroglobulin is present as iodothyronines. L-thyroxine (T4) represents 90-95% of hormonal iodine, 3,5,3'-triodo-L-thyronine (T3) contains at the most two per cent of it, 3,3'5'-triodo-L-thyronine (rT3) even less, as well as traces of 3,3'-diodo-L-thyronine. The plasma concentration of T4 is about 8 microgram per 100 ml, in the case of T3 it is 120 ng and 25 ng for rT3. The cell nucleus preferentially binds T3 and rT3 and there are also some specific mitochondrial proteins which possess a high affinity for T3. L-thyroxine is dehalogenated peripherically to T3, to take care of most of the requirements in T3. The enrichment of the plasma in rT3 has been shown to occur under various experimental and pathological conditoins. The blood level of T3 varies in inverse ratio to the level of rT3 and it shows that the peripheral formation of one is compensated for by the other. The excess of the prehormone T4 is metabolised as 3,5,3',5'-tetraiodothyroacetic acid (TetrAc); its level in the blood varies in the same way as the level of T3, in particular it decreases during starvation.

Circular countercurrent-distribution behavioral genetic maze

An inexpensive, easily constructed apparatus for mass screening of taxes of small animals with a rapid and accurate assignment of individual behavior scores has been described that should be of utility in hastening a behavioral geneticist's chores and allow him to handle more populations with fewer mazes. Also, the apparatus is well suited for use within the constraints of the undergraduate laboratory.

Effect of oral contraceptives on platelet monoamine oxidase, monoamine excretion, and adrenocortical function

Studies with animals indicate that there are cyclical changes in the monoamine oxidase (MAO) activity of brain and uterus, and that these changes may be due to changes in estrogen and progesterone levels. To determine if oral contraceptives (OC) alter the tissue MAO activity of healthy women, we measured platelet MAO activity in 7 control women and in 7 women who were receiving combination estrogen-progesterone OC. The platelet MAO of the control women and the women receiving OC did not differ with the use of tryptamine and serotonin as MAO substrates. The two groups did not differ with respect to the following: serum serotonin, plasma tryptophan, plasma tyrosine, and the urinary excretion of tryptamine, tyramine, serotonin, 5-hydroxyindoleacetic acid, creatinine, 17-hydroxycorticosteroids, 17-ketosteroids, and urinary free cortisol. The subjects receiving OC had higher plasma cortisol concentrations than the controls. Two women in the seventh month of uncomplicated pregnancy, who underwent these studies, had higher plasma cortisol and urinary 17-ketosteroid excretion than control subjects. In the remaining tests the results of pregnant subjects did not differ from those of control subjects. We conclude that tissue MAO activity is not altered by OC or pregnancy.

Collecting and processing records from the ultracentrifuge in "real-time" using an on-line computer

An analytical system consisting of an analytical cantrifuge coupled 'on-line' to a computer was assembled and tested. Collection of records from up to 9 solutions was achieved through programmes which sum readings to reduce noise as well as controlling the positioning of the scanner. With this system it was found that the limit on accuracy for molecular weights at concentrations less than 0.01 g cm-3 was +/- 3% estimated from sedimentation equilibrium experiments. The same system was used to collect records for similar concentrations from velocity experiments by employing a scanning schlieren. In this case the accuracy in estimating sedimentation coefficients was similar to those found when measuring photographs. Since the collection yields detailed information about the shape of the sedimenting boundary, the centroids of the boundary were routinely computed by second moment analysis rather than relying on the position of the maximum of the schlieren peak. In the same analysis estimates of diffusion coefficients were made routinely by calculating corrected height/area ratios for each scan. These calculations were made during the real-time of the experiment, so making available molecular parameters rather than records which must be evaluated some time after stopping the experiment.

Therapeutic doses of cyproheptadine do not inhibit monoamine oxidase in man

Cypro, a serotonin and histamine antagonist, has been shown to be a moderately potent reversible inhibitor of tissue monoamine oxidase (MAO) obtained from hamsters and rabbits. In the present study, Cypro inhibits MAO obtained from human platelets with the same potency as harmine (Ki = 5 x 10(-5) M). However, when ten normal volunteers received conventional therapeutic doses of Cypro (16 mg/day) for two days, there was no alteration in their urinary excretion of tryptamine, 5-hydroxyindoleacetic acid, 3-methoxy-4-hydroxymandelic acid, epinephrine, or norepinephrine. We conclude that, when used in conventional clinical doses, Cypro does not inhibit MAO in man.