Developmental aspects of the innervation of skeletal muscle fibers in the chick embryo

The M. complexus in the chick, commonly called the hatching muscle, undergoes conspicuous growth during the latter stages of embryonic development. Myogenesis of this muscle was compared to that of M. biceps femoris with regard to development of types of muscle fiber and their innervation. In both muscles beta fibers are of relatively uniform size and show little growth in diameter between 12 days of development and hatching; alpha fibers develop continuously and display a wide range of diameters at all stages. Initial thickenings on the sarcolemma of beta fibers where axons are closely approximate were first observed at 10 days of development in both muscles. In both muscles beta fibers are innervated prior to alpha fibers. Terminal axon networks bridge intercellular spaces and contact beta fibers in different myogenic clusters. alpha fibers that develop on the surface membrane of beta fibers exhibit focal thickenings of the membrane and some cell projections that are directed toward axon-beta fiber contacts. These changes occurred only in alpha fibers of M. complexus. At 14 days of embryogenesis, the processes of synaptogenesis and of myelin formation are less advanced in M. biceps femoris than in M. complexus. At this stage alpha fibers were observed to be innervated in M. complexus, but not yet in M. biceps femoris. Each beta fiber was observed to be encircled by several preterminal axons. It is concluded that the earlier development of M. complexus is correlated with an equally early development of nerve-muscle interactions.

Clinical study on early changes in thyroid function of hyperthyroidism treated with propylthiouracil and a relatively small dose of iodide

In order to compare the acute effects of three kinds of antithyroid agents of iodide (I-), propylthiouracil (PTU) and PTU combined with iodide (PTU+I-) on thyroid function in hyperthyroid patients with diffuse goiter, serum concentrations of thyroxine (T4), triiodothyronine (T3), T3-resin sponge uptake (T3-RU) and free thyroxine index (FT4I) were employed as thyroid function parameters. In the group given iodine (1 mg/day) as iodinated-lecithine, the initial values of T4, T3, T3-RU and FT4I were 20.9 +/- 1.6 microng/100 ml (T4), greater than 740 ng/100 ml (T3), 49.5 +/- 2.3% (T3-RU) and 14.7 +/- 1.8 (FT4I). At the end of one week of therapy, they decreased clearly to 15.6 +/- 2.2 microng/100 ml, 457 +/- 87 ng/100 ml, 42.2 +/- 4.0% and 9.7 +/- 2.4. The so-called "escape phenomenon" from iodide inhibition was observed in serum T4, T3-RU and FT4I values at the end of two weeks of iodide therapy, while serum T3 continued to decrease but the value of T3 was far outside of the normal range. In the PTU group (300 mg/day), thyroid function parameters were 22.5 +/- 0.8 microng/100 ml (T4), greater than 592 ng/100 ml (T3), 54.9 +/- 1.0% (T3-RU) and 18.7 +/- 1.0 (FT4I) before treatment. They decreased continually week by week. At the end of four-week treatment with PTU, the value of each thyroid function parameter was 11.1 +/- 1.9 microng/100 ml, 229 +/- 56 ng/100 ml, 36.6 +/- 4.4% and 5.7 +/- 1.7. In the group of hyperthyroidism simultaneously given both PTU and iodide (300 mg/PTU and 1 mg/iodine), these thyroid function parameters decreased as well as in the group treated with PTU alone for more than two weeks. More rapid or significant decrease of T4, T3, T3-RU and ft4i in PTU+I- group than in PTU group was observed in the present study. These results suggested strongly that iodide alone was not an adequate therapy for hyperthyroidism as well known and they were also compatible with the idea that the concomitant administration of PTU and iodide was more effective in the early phase of therapy of hyperthyroidism than PTU alone.

A mammalian nicking endonuclease

Purification and properties are described for an endonuclease isolated from calf thymus which attacks double-stranded, unmodified DNA, primarily by making single-strand breaks. No detectable acid-soluble products arise from the reaction. Double-strand breaks may occasionally be produced by the introduction of single-strand breaks on opposite strands in close proximity. The enzyme does not attack denatured DNA and is not inhibited by tRNA. Although added divalent cations are not required for activity, the enzyme is inhibited by EDTA, which suggests an essential role for bound cations; reaction is inhibited by Ca2+. The endonuclease has a broad pH optimum and is inactivated by preincubation at temperatures of 45 degrees C and higher. The molecular weight as determined by gel chromatography is about 30 000. Analysis of the products of reaction on a defined substrate, bacteriophage T3 DNA, by sedimentation in alkaline sucrose density gradients indicates limit products with chain lengths of about 0.8 X 10(6) daltons. On electrophoresis in agarose gels these products were shown to be heterogeneous in size. The endonuclease appears to generate 3'-hydroxyl and 5'-phosphate ends. The ability of the endonuclease to utilize bovine DNA as substrate argues against a restriction role for this enzyme.

Correlation of moth sex pheromone activities with molecular characteristics involved in conformers of bombykol and its derivatives

Molecular characteristics of bombykol and its 11 derivatives, which reveal significant correlations with biological activities for single sex pheromone receptor cells of four moth species, Bombyx mori, Aglia tau, Endromis versicolora, and Deilephila euphorbiae, were examined on the assumption of the "bifunctional unit model." Probabilities of bifunctional unit formations of those 12 compounds were assessed with frequency distribution patterns of distances between the proton acceptor, the proton donor, and the methyl group involved in a total of 1,200 conformers. A highly significant correlation exists between biological activity for each species and the probability of a particular bifunctional unit formation: a proton acceptor (A)--a methyl group (Me) unit (A--Me distances: about 6 A) for Deilephila (r = 0.94); a proton acceptor (A)--a proton donor (D)(A--D: about 11 A) for Aglia (r = 0.83); two antagonistic proton donor--methyl units (D--Me: about 14 and 5 A for favorable and adverse unit, respectively) for Bombyx (r = 0.94) and Endromis (r = 0.92).

Studies on fungal polysaccharide. XVII. A new glucuronan "protuberic acid" produced by a fungus Kobayashia nipponica

A water-soluble glucuronan "protuberic acid", [alpha] 22-D minus 83.6 degrees, was isolated and purified from Kobayashia Nipponica, and its physicochemical properties were investigated. The purified protuberic acid was homogeneous as shown by zone electrophoresis, gel filtration over Sepharose 4B, and ultracentrifugation. The sedimentation coefficient was 1.8 S and its intrinsic viscosity was 1.1 dl/g. By gel filtration the molecular weight was estimated to be about 170 000. The results of periodate oxidation, methylation analysis, and partial acid hydrolysis indicated that this acidic polysaccharide has a linear structure of mainly 1, 4-linkages and containing an acid-labile linkage. Reduced protuberic acid, [alpha] 22-D minus 44 degrees, is also described.

[A low response of pituitary growth hormone secretion in the patient with diabetes mellitus after intravenous administration of L-dopa (author's transl)]

Recently, L-dopa has been known as one of drugs to stimulate the secretion of growth hormone from the pituitary gland through dopamine, which is a metabolic of L-dopa, without any changes of serum insulin levels, blood sugar values, fatty acids and amino acids concentrations in the serum of human being. The present study was thus designed to assess the effect of L-dopa on the pituitary gland to secrete the growth hormone in the normal subject and the study was further extended to compare the response of the pituitary secretion of the growth hormone following the administration of L-dopa between in the patient with diabetes mellitus and in the normal subject. In the present experiment, 5 normal subjects and 11 diabetes mellitus without obesity were employed and they received a 30 min infusion of 200 mg L-dopa dissolved in 200 ml physiological saline. In normal subjects, serum growth hormone concentration measured by radio-immunoassay was started to increase within 10 min after L-dopa administration and maximum value of serum growth hormone was obtained 60 min after the drug, mean values of it, 30 ng/ml of serum. Then it was declined sharply upto the values of 2-3 ng/ml. In the patients with diabetes mellitus, on the other hand, maximum value of serum concentration of the growth hormone was only approximately 5 ng/ml of serum obtained between 45 and 75 min after the administration of L-dopa. No changes in the serum concentration of IRI (Immunoreactive insulin) and of blood sugar values were observed by the infusion of L-dopa in both normal subjects and diabetes mellitus. From the above mentioned facts, it was concluded that the ability of pituitary gland to secrete the growth hormone was considerably impaired in diabetics when it was compared with normal subjects.