Amplification of moderately repetitive DNA sequences during chick cartilage differentiation.

A 5-bromo-2'-[3H]deoxyuridine (BrdUrd) probe was isolated to analyze DNAs obtained from various chick tissues and cell types. [3H]BrdUrd-substituted DNA, prepared from limb bud cultures, was sheared and freed from palindromic DNA. Nonradioactive DNA was prepared from embryonic liver, undifferentiated limb bud mesenchyme, sternal cartilage, differentiated limb bud cultures, and BrdUrd-blocked cultures, and was sheared.

Distribution of 5-bromodeoxyuridine and thymidine in the DNA of developing chick cartilage.

In order to study the mechanism of the irreversible effects of BrdUrd on the differentiation of limb bud mesenchyme to cartilage, the reannealing behavior of DNA obtained from such cells was examined. Cells incubated with [3H]thymidine ([3H]dThd) during days 1 and 2 of culture incorporated label into repetitive, moderately repetitive, and unique classes of DNA. In contrast, when 5-bromo-2'-[3H]deoxyuridine ([3H]Brd Urd) was added during the first 48 hr (in the presence of 32 muM BrdUrd), the label was preferentially incorporated into a late moderately repetitive region.

The mucopolysaccharidoses (a review).

The mucopolysaccharidoses are a group of genetic diseases characterized by storage of incompletely degraded glycosaminoglycans. Such storage causes marked distortion of many tissues with consequent severe somatic changes and mental retardation. Storage of glycosaminoglycans results from markedly diminished activity of specific hydrolases requisite for the normal degradation of glycosaminoglycans.

Stimulation of synthesis of free chondroitin sulfate chains by beta-D-xylosides in cultured cells.

Beta-Xylosides stimulate 2- to 6-fold the synthesis of glycosaminoglycans by three types of nonconnective tissue cells (RG-C6, NB41A, and rat hepatoma cells, and normal and simian virus 40 (SV40)-transformed normal human skin fibroblasts. The effect, which is specific for the anomeric linkage and the glycone, is observed in the presence and absence of puromycin. Beta-Xylosides may substitute for xylosylated core protein as initiators of synthesis of chondroitin sulfate chains.

Protective studies with a group A streptococcal M protein vaccine. II. Challange of volenteers after local immunization in the upper respiratory tract.

Twenty-one adult volunteers were immunized at monthly intervals with three doses of purified type 1 M protein of group A Streptococcus. The soluble vaccine in buffer was administered by aerosol spray into the nares and oropharynx; 23 control subjects received a buffer placebo in the same manner. Antibody responses were observed in sera and nasal washings of some but not all vaccines.

Group A streptococcal M protein vaccine: protection following immunization via the respiratory tract.

Previous studies have shown the efficacy of parenteral immunization of volunteers with purified type 1 M protein against challenge with homologous streptococcui (J. clin, Invest. 52: 1885, 1973).

Stimulation of chondroitin sulfate proteoglycan production by chondrocytes in monolayer.

Chondrocytes in monolayer undergo morphological and biochemical changes which culminate in the establishment of cartilage nodules in vitro. Chondroitin sulfate or heparin, added to the culture media of these cells, stimulates the production of chondroitin sulfate proteoglycan over the entire period of culture with a maximum effect during the log phase of growth. In addition, a lag of 2-3 hours is required before an increase in sulfate incorporation into polysaccharide is observed.

Stimulation of synthesis of free chondroitin sulfate chains by beta-D-xylosides in cultured cells.

Previous studies have shown that D-xylose partially overcomes the puromycin inhibition of chondroitin sulfate synthesis in cultured chick embryo chondrocytes. Likewise, D-xylose stimulates chondroitin sulfate synthesis by limb bud mesenchyme cells previously treated with BrdU or limb bud cartilage cells treated with puromycin. The studies reported here show that p-nitrophenyl-beta-D-xylopyranoside and 4-methyl-umbelliferyl-beta-D-xylopyranoside cause a much greater stimulation than does D-xylose and are active at much lower concentrations.

Sanfilippo A syndrome: sulfamidase deficiency in cultured skin fibroblasts and liver.

The Sanfilippo A syndrome is an autosomal recessive mucopolysaccharidosis characterized clinically by severe mental retardation and biochemically by storage in tissue and excretion in urine of excessive amounts of heparan sulfate. Since sulfamide groups are present in heparan sulfate, a sulfamidase deficiency could explain the impaired degradation of this polysaccharide. To investigate the enzymic basis of this disease, assays for sulfamidase were performed.