Search

The role of acidic cellular organelles in regulating the toxicity of selected antitumor drugs was studied with L1210 cells using modifiers of vesicular pH or function. A 1 hr exposure to a non-toxic concentration of the acidotropic weak base ammonium chloride increased the lethality of bleomycin A2 (BLM A2), demethyl BLM A2, peplomycin, and talisomycin S10b to L1210 cells grown in culture. Enhanced BLM lethality was also seen with the lysosomal disruptive agents verapamil and diltiazem. The increased lethality with verapamil and BLM A2 was schedule dependent, being seen only when cells were exposed to the drugs simultaneously or to BLM A2 first and then verapamil. Non-toxic concentrations of the monovalent cationic ionophore monensin also increased the cytotoxicity of BLM A2 and talisomycin S10b but not doxorubicin. This enhanced cytotoxicity seen with monensin occurred without an increase in either cell associated BLM A2 or single-strand DNA damage as measured by alkaline elution. We propose that acidic cellular organelles or their contents participate in controlling the cytotoxicity of the BLM class of antitumor agents.

Bone matrix and tendon are compared in terms of their carbohydrate and non-collagenous protein composition. The collagen content of both tissues was similar (90-91%), but bone matrix had at least three times as much sialic acid (0.28%) as tendon (0.08%). Smaller differences were found in the analysis of hexoses and hexosamines. After digestion with bacterial collagenase, about 9% of the total protein from both tissues was non-diffusible on dialysis, and this contained only 0.15% (bone) and 0.7% (tendon) of the original hydroxyproline; recovery of sialic acid was 86-87%. The collagenase-resistant soluble material amounted to about 9% (bone matrix) and 5% (tendon); the insoluble residues were 1 and 4% respectively. There were clear differences in the carbohydrate contents of the digests, but the amino acid compositions were similar. When the soluble digests were chromatographed on DEAE-cellulose, the elution profiles indicated the presence in each tissue of a variety of glycoproteins and a proteoglycan fraction, and showed clearly that an acidic glycoprotein corresponding to bone sialoprotein was not present in tendon.

A method has been developed for the solubilization of bone matrix using bacterial collagenase. The soluble macromolecules were separated by a column procedure on DEAE-cellulose and analysed for uronic and sialic acids. Values for the total non-collagenous fraction of bone and its content of bone sialoprotein and chondroitin sulphate were obtained. The method was compared with similar procedures using EDTA extraction and papain digestion.

Rabbit cortical bone powder was extracted with EDTA solutions at neutral pH and the soluble constituents fractionated by DEAE-cellulose chromatography. The acidic fractions obtained were further investigated by gel chromatography and chemical analysis. Two classes of proteoglycans were present; one containing chondroitin sulphate and the other containing material resembling keratan sulphate mixed with a smaller amount of chondroitin sulphate. Sialoglycoproteins were detected by specific chemical introduction of tritium label into the sialic acid residues of the acidic glycoprotein fraction. Following sodium dodecyl sulphate-polyacrylamide gel electrophoresis and fluorography, the presence of numerous distinct sialoglycoprotein components was demonstrated.

The study measured cost-effectiveness of home care for severely disabled persons. Findings support home care as more cost-effective than other alternatives for ventilator-dependent persons. Home care-related policy reform in Medicaid, Medicare, Supplemental Security Income, and subsidized housing, coupled with a coordinated service delivery system, could save millions of public dollars. To accomplish this, policies must accommodate and encourage independent community living for the disabled and the integrity of their families.

A fraction containing chondroitin sulphate, isolated from bovine cortical bone under mild conditions, was separated by ion-exchange chromatography into three fractions with apparent homogeneity on electrophoresis and ultracentrifugation. Two of these appeared to consist of chondroitin sulphate bound to a glycoprotein ;core' that had similarities to the bone sialoprotein described previously. The differences in composition of the two fractions were considered to be due to variation in the number or lengths of the polysaccharide chains. The presence of xylose and the alkali-lability of the bond between protein and polysaccharide suggested the presence of a xylosylserine linkage. The third fraction had the properties of a relatively pure chondroitin sulphate which contained a small amount of peptide. These fractions differed considerably from the protein-polysaccharide complexes of epiphysial and other cartilages, and their relevance to the possible role of glycosaminoglycans is discussed.

1. Bovine bone sialoprotein (mol.wt. 23000) contains N-acetylneuraminic acid and N-glycollylneuraminic acid, fucose, galactose, mannose, N-acetylgalactosamine and N-acetylglucosamine residues in the form of a very small number, perhaps one, of highly branched oligosaccharide structures linked covalently to peptide. 2. Periodate oxidation of the sialoprotein results in quantitative destruction only of the sialic acid and fucose residue consistent with the earlier findings of their positions as terminal groups. 3. Terminal sialic acid residues are attached to galactopyranose residues by 2,3-linkages, and to some N-acetylgalactosamine residues (at C-6). 4. Sequential Smith degradation indicates that N-acetylgalactosamine residues may be present as points of branching (linked in C-1, C-3 and C-6) and N-acetylglucosamine residues are located in the inner part of the structure, adjacent to the carbohydrate-peptide bond(s). 5. Mannose residues appear to be linked in the 1,3-positions.