Glycosaminoglycans produced by human synovial cell cultures

Human synovial cells in culture are known to synthesize hyaluronic acid, but the production of sulfated glycosaminoglycans (GAG) has received less attention. Using 14C-glucosamine as a precursor, GAG content was studied in the medium, trypsin-solubilized pericellular layer, and cell residue fraction of cultured synovial cells derived from the synovial membranes of nonrheumatoid and rheumatoid joints. Over 90% of the total non-dialyzable counts appeared in the culture medium, for the most part in hyaluronic acid. The remaining nondialyzable counts were cell-associated, almost equally divided between the pericellular layer and cell residues. In these fractions, only part of the counts were in GAG susceptible to testicular hyaluronidase digestion, and GAG were significantly lower in the cell residue of the rheumatoid synovial cells compared to the nonrheumatoid cells. Analysis of the chondroitinase ABC and AC digestion products of these GAG indicated the presence of chondroitin-4 and -6 sulfates, and dermatan sulfate, but not heparan sulfate. Similar findings with respect to the identity of the GAG in nonrheumatoid and rheumatoid synovial cell culture media were obtained with 35SO4 as a precursor.

Identification of fatty acid synthetase messenger RNA on free polyribosomes isolated from lactating rabbit mammary gland

The synthesis of fatty acid synthetase on free polyribosomes from lactating rabbit mammary gland was demonstrated by using polyribosomes run-off techniques and immunochemical identification of products with synthetase antiserum. Several reproducible and discrete immunoprecipitable polypeptides were observed which were within the molecular-weight range of the synthetase subunit (235 000--252 000), as well as several of lower molecular weight.

Formulation and application of a numerical scoring system for assessing histological activity in asymptomatic chronic active hepatitis

A Histology Activity Index has been developed which generates a numerical score for liver biopsy specimens obtained from patients with asymptomatic chronic active hepatitis. Biopsies are graded in four categories: periportal necrosis, intralobular necrosis, portal inflammation, and fibrosis. Under code, three pathologists and three hepatologists evaluated 14 liver biopsy specimens obtained from five patients with asymptomatic chronic active hepatitis. Good correlation was seen between severity of liver biopsy lesions as judged by conventional histological descriptions and Histology Activity Index scores. Significant differences in Histology Activity Index score occurred in only 2 or 28 duplicate scorings of biopsy specimens by two observers. This system provides definitive endpoints for statistical analysis of serial changes in liver histology and offers an alternative to the use of conventional pathological descriptions in following the natural history and treatment responses of asymptomatic chronic active hepatitis.

Malnutrition and hyperglycemia associated with TPN do not alter polymorphonuclear leukocyte adherence to nylon

Polymorphonuclear leukocyte (PMN) adherence to nylon was assayed in blood obtained from 10 malnourished patients before and during therapy with total parenteral nutrition (TPN). All patients demonstrated minimal to moderate loss of visceral and somatic protein. Adherence of PMN was unaltered by malnutrition or during the 4 wk of TPN in spite of hyperglycemia, which required insulin therapy in 4 patients. There was no correlation of blood sugar levels and PMN adherence.

The influence of topology and glycosylation on the fate of heterologous secretory proteins made in Xenopus oocytes

Secretory proteins made in Xenopus laevis oocytes under the direction of heterologous messenger RNA are modified, topologically segregated and exported. Thus the oocyte may serve as a useful surrogate secretory system and we have studied some of the factors governing access to the export pathway. Unglycosylated chicken ovalbumin, synthesized and trapped in the cytosol, is not secreted but glycosylated ovalbumin, found sequestered within vesicles, is exported from oocytes. However, ovalbumin, which is transferred across the endoplasmic reticulum in the presence of tunicamycin and which is indistinguishable by immunoprecipitation, by two-dimensional gel electrophoresis and by concanavalin-A--Sepharose binding from the cytosolic form, is still secreted. Guinea-pig milk proteins and human interferon are also exported from tunicamycin-treated frog cells. These observations demonstrate that access to the endoplasmic reticulum but not glycosylation is a mandatory intermediate step in secretion, and emphasize the advantages of the oocyte as a surrogate system for the study of the later events in the gene expression pathway.

The Xenopus oocyte as a surrogate secretory system. The specificity of protein export

Combining messenger RNA from one kind of secretory cell with the cytoplasm of another such cell can reveal the nature and specificity of protein export mechanisms. We show that messenger RNAs from secretory cells of chickens, rats, mice, frogs, guinea-pigs, locusts and barley plants, when injected into Xenopus oocytes, direct the synthesis and export of proteins. Chicken ovalbumin, Xenopus albumin, mouse thyroid-stimulating hormone, locust vitellin and guinea-pig milk proteins were identified using specific antibodies, whilst chicken lysozyme and ovomucoid, rat albumin, Xenopus vitellogenin and rat seminal vesicle basic proteins were identified provisionally from their molecular weights. Certain endogenous proteins are sequestered and secreted although most oocyte proteins are not exported. Similarly the major polyoma viral protein and the simian virus 40 and polyoma tumour antigens are retained within the oocyte. Radioactive proteins exported by oocytes programmed with chicken oviduct or Xenopus liver RNA are not re-exported in detectable amounts when injected into fresh oocytes, nor is there secretion of chicken oviduct or guinea-pig mammary gland primary translation products prepared using wheat germ extracts. Thus the export of secretory proteins from oocytes cannot be explained by leakage and may require a cotranslational event. The secretory system of the oocyte is neither cell-type nor species-specific yet is highly selective. We suggest that the oocyte can be used as a general surrogate system for the study of gene expression, from transcription through translation to the final subcellular or extracellular destination of the processed protein.

Glucose metabolism in uremia

Formation of CO2 from uniformly labeled 14C-glucose was measured in liver slices from uremic and normal rats. Both CO2 formation and lactate concentration were decreased in the uremic liver slices suggesting an inhibition of glucose oxidation. In addition, a net loss of glucose from the medium in the uremic preparation and a net gain in the normal controls suggested that there was increased nonoxidative utilization in the uremic liver. Such changes could not be explained by differences in glucose availability consequent to alterations in glycogen degradation. The most likely explanation is diversion of glucose into other biosynthetic pathways such as the synthesis of amino acids. In this regard, synthesis of glutamine appeared to be enhanced in uremia. Thus, products of carbohydrate metabolism may provide a potential mechanism for disposition of ammonia and synthesis of amino acids in uremia.

Sequestration and turnover of guinea-pig milk proteins and chicken ovalbumin in Xenopus oocytes

The stability and distribution of proteins within the living cell can be studied using Xenopus laevis oocytes. Microinjection of messenger RNAs and secretory proteins, followed by cell fractionation, shows that transfer of ovalbumin and milk proteins across intracellular membranes of the oocyte only occurs during their synthesis. Thus milk protein primary translation products, made in the wheat germ cell-free system, when injected into oocytes remain in the cytosol and are not recovered within membrane vesicles. Such miscompartmentalized primary milk proteins are rapidly degraded (t 1/2 0.6 +/- 0.1 h). In contrast, processed milk proteins, extracted from oocytes injected with mammary gland RNA, are relatively stable when introduced into the cytosolic compartment (t 1/2 alpha-lactalbumin 20 +/- 8 h, casein A 6 h, casein B 4 h, casein C 8.3 h). The primary ovalbumin product is also stable (t 1/2 22 +/- 9 h). Indirect evidence that rapid degradation of miscompartmentalized milk protein primary translation products may occur in vivo was obtained by the injection of massive amounts of ovalbumin and milk protein mRNA. Under these conditions there is no accumulation of primary milk protein translation products, but a polypeptide resembling the unglycosylated ovalbium wheat germ primary product can be detected in the cytosol. Only the glyclosylated forms of ovalbumin are found in the oocyte membrane vesicle fraction. We discuss the roles played by the presence of detachable signal sequences and the absence of secondary modifications in determining the rate of degradation of primary translation products within the cytosol.

Assembly of smooth muscle myosin into side-polar filaments

The in vitro assembly of myosin purified from calf aorta muscle has been studied by electron microscopy. Two types of filament are formed: short bipolar filament similar to those formed from skeletal muscle myosin, and longer "side-polar" filaments having cross bridges with a single polarity along the entire length of one side and the opposite polarity along the other side. Unlike the case with skeletal myosin filaments, antiparallel interactions between myosin molecules occur along the whole length of side-polar filaments. The side-polar structure may be related to the in vivo form of myosin in vertebrate smooth muscle.

Results of BCG adjuvant immunotherapy in 100 patients with epidermoid carcinoma of the head and neck

One hundred patients with advanced, recurrent, or metastatic squamous cell carcinoma of the head and neck were treated with chemotherapy and BCG as adjuvant immunotherapy. The overall response rate was 35 per cent, and the median duration of response was seventeen weeks. BCG does not prolong duration of remission or survival time.

The location of C-protein in rabbit skeletal muscle

Antibodies to C-protein have been used to label fibres of glycerinated rabbit psoas muscle. The labelling patterns observed in the electron microscope show that C-protein is located on 7 stripes, spaced about 43 nm apart in each half of the A-band. Between two and four C-protein molecules per filament are present at each stripe. The labelling patterns also reveal the existence of two previously unrecognized components of the thick filament present in two further stripes in each half of the A-band. The location of C-protein and these other components accounts for many of the stripes seen in sections of the A-band and in negatively stained A-segments and provides new information on the packing of myosin molecules in the thick filament.