Purification and characterization of M3 protein expressed on the surface of group A streptococcal type 3 strain C203

Abstract Monoclonal antibodies (mAbs) have been produced by immunizing BALB/C mice with whole M⁺ bacteria in incomplete Freund adjuvant and the resulting mAbs for M3 protein have been selected by an indirect immuno-fluorescent technique using formaldehyde-fixed M⁺ and M⁻ bacteria. Four mAbs reacted with a 65 kDa protein in an extract obtained from the cell wall of M⁺ bacteria after treatment with N -acetyl muramidase and lysozyme. The purified 65 kDa protein neutralized the phagocytic activity of rabbit anti-M3 antibody. The N-terminal amino acid sequence of the 65 kDa protein was identical with that of protein generated by the M3 gene which has been previously cloned and sequenced. The evidence indicates that the 65 kDa protein is M3 protein. The M3 protein bound not only human fibrinogen but also human serum albumin (HSA). When the M3 protein was purified by gel-filtration and ion-exchange chromatography in the absence of phenylmethyl sulfonyl fluoride (PMSF), four fragments (35 kDa, 32 kDa, 30 kDa, and 25 kDa) in addition to the intact molecule appeared. N-terminal amino acid sequence analysis showed that 35 kDa and 25 kDa fragments were ANAAD and DARSV, respectively, being identical at positions 1–5 and 198–202 to the M3 gene derived protein. Therefore, the 35 kDa and 25 kDa fragments, which were presumed to be cleavage products, may be derived from the C-terminal part and N-terminal part of the intact molecule, respectively. When the effect of purified M3 protein in the bactericidal activity of normal human blood in the presence of M⁻ bacteria was investigated, the M3 protein was responsible for the organism's resistance to attack by phagocytic cells.     

In vitro study on release of thyroid hormone in solitary autonomously functioning thyroid nodules using cell culture method

In vitro release of thyroid hormone was investigated under basal and TSH-stimulated conditions in the solitary autonomously functioning thyroid nodules (AFTN). A small portion (0.5 g of wet weight) of the nodules and adjacent thyroid tissues removed surgically from five patients with solitary AFTN were prepared for the dispersed cell culture. In the experiment on non TSH-stimulated (basal) conditions, those culture media which were totally replaced on the 5th day after primary culture were utilized for the determination of thyroxine (T4) and triiodothyronine (T3) by radioimmunoassay. T4 and T3 levels in culture media of the functioning nodules were 1.15 +/- 0.33 microgram/dl (mean +/- SEM) and 2.72 +/- 0.68 ng/ml, contrasted with levels of 0.67 +/- 0.09 microgram/dl and 1.24 +/- 0.22 ng/ml in the paranodular tissues. The mean ratios of T3/T4 of the nodules and paranodular tissues were 0.25 +/- 0.02 and 0.19 +/- 0.02, respectively (p less than 0.05). Meanwhile, in another experiment under TSH stimulatory conditions employing 40 and 80 microU/ml of human TSH, there were no significant differences in T4 and T3 releases when the two groups were compared.     

Identification of 19-nor-deoxycorticosterone in normal rat serum by enzyme immunoassay and gas chromatography-mass spectrometry

Recent reports on the isolation and identification of 19-nor-deoxycorticosterone from the urine of rats with adrenal regeneration hypertension give rise to the possibility of a role of this steroid in the pathogenesis of low renin essential hypertension. The present study was undertaken to investigate the presence of 19-nor-deoxycorticosterone in normal rat serum both by a sensitive enzyme immunoassay and by gas chromatography-mass spectrometry (GC/MS). 19-Nor-deoxycorticosterone in rat serum was separated from other steroids prior to enzyme immunoassay by using high performance liquid chromatography (HPLC). The average concentration of 19-nor-deoxycorticosterone in normal rat serum was 137 +/- 62 ng/dl (mean +/- SD, n = 32). Pooled normal rat serum (50 ml) was purified by HPLC and the purified sample was acetylated with acetic anhydride for GC/MS measurement. The retention time and m/z ions (358, 285, and 257) on the resulting mass fragmentogram coincided in position with those of authentic 21-acetoxy-19-nor-deoxycorticosterone and acetylated normal rat serum extract. The combined characteristics of HPLC elution, antigen-antibody reaction, GC retention and selected ion responses provided strongly evidence supporting the presence of 19-nor-deoxycorticosterone in normal rat serum.     

Effect of sulpiride on serum growth hormone and prolactin concentrations following L-DOPA administration in man.

The effect of chronic administration of sulpiride on serum human growth hormone (hGH), prolactin and thyroid stimulating hormone (TSH) was examined in 6 normal subjects. Sulpiride was given orally at a dose of 300 mg (t.i.d.) for 30 days. Sulpiride raised serum prolactin levels in all subjects examined. In addition, sulpiride suppressed hGH release induced by L-dopa, although the basal hGH level was not changed. Sulpiride treatment appeared to antagonize partially the inhibitory effect of L-dopa on prolactin release. Following thyrotropin-releasing hormone (TRH) injection, the percent increment in prolactin levels from the baseline in sulpiride-treated subjects was less than in controls without sulpiride. In contrast, both the basal and TRH-stimulated TSH levels were not influenced by sulpiride. These observations suggest that sulpiride suppresses L-dopa-induced hGH release and stimulates prolactin release, presumably by acting against the dopaminergic mechanism either on the hypothalamus or on the pituitary. The decreased prolactin response to TRH after sulpiride treatment may indicate a diminished reserve capacity in pituitary prolactin release.     

Relationship between tubulin SH groups and bound guanine nucleotides.

Guanine nucleotides bound to both the non-exchangeable sites (N sites) and exchangeable sites (E sites) of tubulin were completely released after 7 moles of SH groups per tubulin subunit (55,000 molecular weight) had reacted with PCMPS. The blockage of 2 moles of SH groups in the glycerol-reassembly buffer or 1 mole of SH groups in glycerol-free reassembly buffer resulted in complete loss of tubulin polymerizability. However, under both sets of experimental conditions, the amount of guanine nucleotides released from the E sites was less than 8% and the loss of total guanine nucleotides was only 5%. Addition of GSH did not induce reassociation of released guanine nucleotides, although it restored tubulin polymerizability. These results indicate that the loss of tubulin polymerizability on blockage of the SH groups was not due to dissociation of bound guanine nucleotides and that the binding sites of the nucleotides were independent of the SH groups in tubulin required for polymerization. Furthermore, blockage of SH groups did not change the ratio of GTP to GDP bound to tubulin.     

On the role of recA gene product in genetic recombination: an analysis by in vitro packaging of recombinant DNA molecules formed in the absence of protein synthesis.

Summary The role of the recA gene product of Escherichia coli in genetic recombination was examined in a system where recombination takes place in the absence of protein synthesis. recA200 bacteria were infected with two mutant strains of phage lambda in the presence of chloramphenicol and rifampin, and the resulting recombinant DNA molecules were measured by in vitro packaging. When recA200 bacteria grown at a temperature that is permissive for RecA phenotype were transferred to a temperature that is restrictive for RecA phenotype in the presence of the inhibitors, recombination of the infecting phages was severely blocked. This result shows that the recombination activity of the recA200 cells is inactivated by the change of temperature even in the absence of protein synthesis. The most likely explanation of this result is that the recA protein is directly involved in the recombination detected in the presence of chloramphenicol and rifampin.     

Translation of human interleukin 2 mRNA in Xenopus laevis oocytes

Poly(A)-positive mRNA extracted from tonsillar mononuclear cells stimulated with phytohemagglutinin-M and 12-o-tetradecanoyl phorbol 13-acetate was successfully translated into biologically active interleukin 2 (IL-2) in Xenopus laevis oocytes, and secreted into the incubation medium. In control experiments, the extract of oocytes injected with either poly(A)-negative RNA or buffer did not show any IL-2 activity. By sucrose density gradient centrifugation analysis, IL-2 mRNA was found as a single peak corresponding to a sedimentation coefficient of 10-11S.     

Rabbit-liver phosphorylase: improvement of the purification procedure and assay of the inactive b form

Continuous electrophoresis buffers are described for polyacrylamide gels at pH values ranging from 3.8 to 10.2. The buffers consist of an acidic and a basic component with pK values near the pH of the buffer. The pH is maintained to within 0.5 pH unit in the electrode compartments during prolonged electrophoresis. Some proteins produce clear bands on gels with each of the 10 buffers. The buffers provide an expansion of the pH range of gel electrophoresis and are likely to be useful in the detection of genetic variation in proteins and in other applications.     

Decalcification for Electron Microscopy with L-Ascorbic Acid

L-Ascorbic acid decalcification was used for electron microscopy of mammalian tooth germs and bone after fixation in a glutaraldehyde-paraformaldehyde mixture. The recommended decalcifying solution is 2% with respect to L-ascorbic acid and 0.9% with respect to sodium chloride. The method has the advantage that decalcification is complete within a quarter of the time required with EDTA. The fine structure of ameloblasts and hard tissue is preserved as well as with EDTA.