Sulphation of secreted phosphoprotein I (SPPI, osteopontin) is associated with mineralized tissue formation

Secreted phosphoprotein I (SPPI) is a prominent structural protein in mineralized connective tissues. Rat bone cells in culture produce several forms of SPPI that differ in post-translational modifications such as phosphorylation and sulphation. To determine the significance of protein sulphation in bone formation, the synthesis of SPPI was studied in vitro using rat bone marrow cells (RBMC) which form bone-like tissue when grown in the presence of dexamethasone (Dex) and beta-glycerophosphate (beta-GP). In the presence of 10(-7) M Dex SPPI expression was stimulated 4-5-fold. Radiolabelling multilayered RBMCs for 48 h with [35S]-methionine, Na2[35SO4], or Na3[32PO4] revealed that two major phosphorylated forms of SPPI were secreted into the culture medium: a highly phosphorylated form migrating at 44 kDa on 15% SDS-PAGE and a less phosphorylated 55 kDa form. In the mineralized tissue formed in the presence of Dex and beta-GP, both forms of SPPI, in addition to proteoglycans and a 67 kDa protein, incorporated significant amounts of [35SO4]. Sulphation of SPPI was not observed in the absence of mineral formation, indicating that the sulphation of SPPI is closely associated with mineralization and that it can be used as a sensitive and specific marker for the osteoblastic phenotype.

Forward masking effects on early auditory evoked potentials

In early auditory evoked potentials (EAEPs) evoked by click trains, every click had a masking effect on the responses to the clicks following it and the whole response evoked by the click train was the sum of the masked responses to every click in the train. Special attention was paid to the situation when the inter-stimulus interval (ISI) was less than 10 ms and the responses to the individual clicks might be merged to form a continuous wave. The experiments showed that the more the number of the clicks preceding a given click in the train, the stronger the effect on the response to this click until the number was big enough and the effect became saturated; the shorter the ISI when it was less than 10 ms, the stronger the effect; the higher the intensity of the masker, the stronger the effect.

Multiple forms of SppI (secreted phosphoprotein, osteopontin) synthesized by normal and transformed rat bone cell populations: regulation by TGF-beta

Metabolic labeling has revealed that rat bone cell populations in culture synthesize several forms of the secreted phosphoprotein, SppI. Most cell populations produced two major [32PO4]-labeled forms that behaved anomolously on SDS-PAGE migrating at 60 kDa and 56 kDa on 10% gels and 55 kDa and 44 kDa on 15% gels. Minor forms of intermediate sizes were also resolved. In normal bone cells the 60 kDa form was predominant and was the only form produced by the clonal bone cell line, RCA 11, whereas the 56 kDa a form predominated in the transformed bone cell line, ROS 17/2.8. In all populations [35S]-methionine-labeling revealed SppIs at approximately 60 kDa but no 56 kDa form. Each form of SppI was specifically cleaved by thrombin which generated fragments of approximately 28 kDa. Transforming growth factor beta 1 increased SppI mRNA levels 3 to 6-fold within 24 h in the normal bone cells, but no increase occurred in the ROS 17/2.8 cells. The elevated expression of SppI was reflected in a selective increase in the synthesis of the [32PO4]-and [35S]-methionine-labeled 60 kDa SppIs.

Genetic diversity of six isozyme loci in cultivated barley of Tibet

A random sample of 463 accessions of cultivated barley from the Tibet Hordeum germplasm collection was assayed electorphoretically for genetic diversity at six isozyme loci. Two loci (Acp-1 and Got-1) were found to be monomorphic and extensive variation was detected at the remaining four loci (Est-1, Est-2, Est-3 and Est-4). The allelic composition of Tibetan barley appeared to be distinct as compared to the results of previous studies of barleys from other parts of the world. Partitioning of genetic diversity showed that approximately 96% of the total variation was maintained at the within-subregion level and only about 4% was accounted for by differentiation among the eight subregions. Analysis of multilocus genotypes revealed non-random association of the alleles at the four loci, both in the entire sample and in all the subregions, although the four major multilocus genotypes did not show significant departure from the expectation based on complete random association. The possible causes for the establishment of these multilocus associations were discussed.

[The penetration of cephalosporins across the blood-brain barrier and its clinical significance]

The penetration of Cefuroxime (CXM), Ceftazidime (CTZ), Cefotaxime (CTX), Ceftizoxime (CZX), and Ceftriaxone (CTRX) across the blood-brain barrier was studied in 119 patients with or without meningitis after an intravenous injection of 2 grams. Cephalosporins were undetectable or their concentrations very low in the cerebrospinal fluid (CSF), when there was no inflammation in the meninges. On the contrary, the mean CSF concentrations of cephalosporins were 2.21-5.36 micrograms/ml and the CSF/serum ratios 3.73-31.80% in acute stage of purulent meningitis. The CSF levels of all the five cephalosporins were much higher than the mean MICs of the common pathogens of bacterial meningitis as well as that of Enterobacteriaceae. It is thus shown that these five new cephalosporins are useful for treatment of meningitis including those caused by gram-negative bacilli.

The detection of an antibody against IgA allotype A2M 2 and a study of the Am genetic marker among the Han Chinese population

The serum of a woman was found by the Ouchterlony double-diffusion and the hemagglutination inhibition (HAI) methods to have immunoglobulin A (IgA) deficiency. Further investigation using the hemagglutination (HA) test with red cells coated with IgA myeloma proteins of different specificities showed that the serum agglutinated only IgA2-, A2M-1, and A2M 2-coated cells. The patterns of the HAI test with a reference panel confirmed the presence of two specificities. One was anti-IgA2 and the other was a rare antibody against the allotype A2M 2. The anti-A2M 2 was used for population studies. Testing of the Han Chinese population, including family studies, confirms that A2M.1 and A2M.2 have an autosomal dominant mode of inheritance and are controlled by a codominant allele. The distribution of the two Am genetic markers among the Han Chinese population demonstrated A2M.1 with a gene frequency of 0.553 and A2M.2 with a gene frequency of 0.447 (chi 2 = 0.145, 0.80 greater than p greater than 0.70).

[The content of tyrosine in rat luteal cell and the changes caused by hCG, cAMP and progesterone]

The ovaries taken from the immature female rats primed with PMSG-hCG were digested with collagenase-DNAase solution to obtain the luteal cell suspensions. Luteal cells were then incubated with different doses of hCG, cAMP or progesterone for 1.5 hours. The contents of tyrosine in luteal cell suspensions were determined by thin layer chromatogram using dual-wavelength chromatogram scanner. It was found that the content of tyrosine in rat luteal cell suspensions was 1.41 + 0.24 nmol/L/10(6) cells after one hour incubation. hCG, cAMP and progesterone all could significantly increase the content of tyrosine in the suspensions, suggesting the release of "endogenous tyrosine". The increase of tyrosine was not due to increased transformation of phenylalanine, the precursor of tyrosine, and increased protein synthesis, because both phenylalanine and cycloheximide failed to influence such increase.

[Effects of human atrial natriuretic factor-(99-126) on plasma and brain vasopressin in stroke-prone spontaneously hypertensive rats]

In order to investigate the interaction between atrial natriuretic factor (ANF) and arginine vasopressin (AVP) in the pathogenesis of essential hypertension, the effects of intravenous (iv) or intracerebroventricular (icv) injection of human ANF-(99-126) on plasma and brain AVP, as well as mean arterial pressure (MAP), urinary volume (UV) and sodium (UNaV) excretion in stroke-prone spontaneously hypertensive rats (SHRsp) and age-matched normotensive Wistar-Kyoto rats (WKY) were studied. The results showed that ten minutes after iv injection of ANF, MAP decreased by 9.4% and 12.2% (P less than 0.05), UV increased about 9 and 20 folds (P less than 0.01), UNaV increased about 16 and 29 folds (P less than 0.01) in SHRsp and WKY rats, respectively. No such significant changes in these parameters were found in the icv group. Although iv and icv injection of ANF caused significant decrease of plasma AVP in both strains, the decrease was less marked in SHRsp than in WKY rats, while the maximum decreases were 58% (iv) and 31% (icv) in SHRsp, the corresponding values were 80% (iv) and 65% (icv) in WKY. Intravenous and intracerebroventricular injection of ANF also induced significant increase of hypothalamic AVP in both SHRsp and WKY rats, but no significant change could be found in hypophyseal AVP content. The results suggest that decreased sensitivity of AVP inhibition as well as less marked hypotensive, diuretic and natriuretic effects to ANF in SHRsp might play a role in the pathogenesis of their hypertension.

Characterization of multiple forms of small collagenous apatite-binding proteins in bone

A number of small (Mrs 25-28 kDa) collagenous apatite-binding (SCAB) proteins that stain blue with 'Stains-All' have been isolated from fetal porcine bone by sequential extractions with 4M GuHCl (G1), followed by 0.5M EDTA (E), and again with 4M GuHCl (G2). Following purification under dissociative conditions, two types of SCAB proteins both with approximately one-third of their structure being collagenous, were identified in the EDTA extract. One type, which appears to be a novel protein, was revealed in two forms (SCABs 1 and 2, Mrs 25 and 28 kDa) that were recognized by a monoclonal antibody (MBP-322). The second type, SCAB 3, was also present in two forms; one form (SCAB 3a) having a lower affinity for hydroxyapatite than the other (SCAB 3b). These proteins were resistant to CNBr and displayed the chemical and immunochemical properties of the alpha 1 pN-propeptide of type I collagen. A third form of the propeptide (G2-28K) was a prominent component of the second 4M GuHCl extract. The chromatographic properties of serum alpha 1 (I) pN-propeptide were similar to SCAB 3a, indicating that SCAB 3b and G2-28K are post-translationally modified forms of the propeptide produced by bone cells. These propeptides may provide a link between the hydroxyapatite and collagen fibrils, and also have the potential to suppress collagen synthesis during bone resorption.

Chloroplast DNA diversity in populations of wild and cultivated barley

Chloroplast DNA (cpDNA) diversity was found within and among populations (245 accessions total) of wild barley, Hordeum vulgare L. ssp. spontaneum Koch from Israel and Iran. Three polymorphic restriction sites (HindIII, EcoRI, BclI) which define three distinct cpDNA lineages were detected. One lineage is common to populations in the Hule Valley and Kinneret of northern Israel, and in Iran. The second lineage is found predominantly in the Lower Jordan Valley and Negev. The distribution of the third lineage is scattered but widespread throughout Israel. Sixty two accessions of cultivated barleys, H. vulgare L., were found, with two exceptions, to belong to just one cpDNA lineage of wild barley, indicating that the cpDNA of cultivated barley is less variable than its wild ancestor. These results demonstrate the need for assessing intraspecific cpDNA variability prior to choosing single accessions for phylogenetic constructions at the species level and higher.

Detection of ABR thresholds with a statistical synchrony measure

Using the method of Fridman and his colleagues, a statistical test of auditory brainstem responses (ABR) for detecting auditory thresholds is presented. The synchrony measure (SM) which represents the degree of reproducibility for group averages was used to calculate the selected Fourier components of the group averages from phase variance. The sensitivity of the test was demonstrated on 35 normal ABRs with 60 and 45 dB SL stimulus intensity and in the absence of stimulus from the ipsilateral recordings. The SM of all cases of normal ABRs at 60 and 45 dB SL exceeded those in the absence of stimulation. The same procedure was applied to 16 ears with cochlear hearing loss with (4 ears) and without (10 ears) recruitment and 2 ears with relatively normal hearing threshold (less than 30 dB HL). Seven out of 10 ears without recruitment had the SM value at 60 dB SL stimulus intensity significantly lower than those of normal ABRs.

Linkage disequilibrium in natural populations of Trypanosoma cruzi (flagellate), the agent of Chagas' disease

We have studied linkage disequilibrium in natural populations of Trypanosoma cruzi, the agent of Chagas' disease, by analyzing (i) a set of 524 stocks from the whole geographical range of the parasite, characterized at four gene loci coding for enzymes; (ii) a subsample of 121 stocks characterized at 12 enzyme loci; and (iii) a subset of 386 stocks from six locations in Bolivia, characterized by four enzyme loci. Our results show that the linkage disequilibrium reaches the maximum possible value, given the observed allelic frequencies, for almost all the locus pairs. This result is most consistent with the hypothesis that genetic recombination is absent or very rare in T. cruzi natural populations. Partition of the linkage disequilibrium variance for the six Bolivian populations shows that both inter- and intrapopulation components are substantial and that the relationships among the components are D2IS less than D2ST, and D'2IS less than D'2ST. These inequalities are interpreted as the result of an interplay between genetic drift, rare or absent mating, and clonal selection in generating linkage disequilibrium in T. cruzi populations.

[Experimental chemotherapy of human gastric cancer cell lines in vitro and in nude mice]

Cytotoxic effects of allyl trisulfide (Alt, a synthetic chemical identical with one of the main active principles of garlic), 5 FU, MMC and DDP on SGC 7901 ( a moderately differentiated human gastric adenocarcinoma cell line) and MGC 803 (a poorly differentiated human gastric mucoadenocarcinoma cell line) had been reported before. In this paper, effects of repeated two doses of each drug and the combination of two drugs on these two cell lines were studied using relative clone-survival test. The inhibitory effects of Alt, MMC alone or combined on MGC tumor in nude mice were observed. No drug resistance was found when any one of the four agents at the same concentration were repeated twice separately at 60 hour interval in vitro. The cytotoxic effect of the repeated two doses was approximately equal to that of the single dose at double concentration. The in vitro test of combinations of two drugs showed that Alt plus MMC or 5 FU plus DDP had markedly synergistic effect on MGC cells; 5 FU plus DDP had markedly synergistic effect on SGC cells. The inhibition test on the growth of MGC tumor in nude mice indicated that the inhibition rates of Alt, MMC alone or combined were 58.3%, 86.3% and 84.3%. The systemic toxic effect of MMC alone was severe, whereas Alt alone or MMC plus Alt showed mild toxicity. For this reason, Alt plus MMC is recommended for clinical trials on poorly differentiated gastric cancer. In addition, for the comparison of in vitro test dose and clinical dose of each drug, the principle of clinical adult dose range (CADR) is proposed.

Detection of antibody to LAV/HTLV-III in sera from hemophiliacs in China

Using ELISA, Western blots and immunofluorescence techniques, we identified seropositivity for lymphadenopathy-associated virus/human lymphotropic virus-III (LAV/HTLV-III) in 4 of 18 hemophiliacs and 1 AIDS patient. The four seropositive patients had received factor VIII prepared by Armour Company. The hemophiliacs are all asymptomatic. Given this documentation of introduction of LAV/HTLV-III into China, a national surveillance program is underway.