Hyaluronan-mediated protective effect against cell damage caused by enzymatically produced hydroxyl (OH.) radicals is dependent on hyaluronan molecular mass

Hyaluronan (HA) protected tendon fibroblasts against cell damage mediated by hydroxyl radicals (OH.) as demonstrated by release of 51Cr from labelled cells. Protection afforded by high molecular mass (M(r)) HA (1218 kDa) was much more effective than that provided by lower (176 kDa and 668 kDa) M(r) HA. OH. was generated by coupling H2O2 produced by glucose oxidase:glucose to [Fe(2+)-EDTA] chelate in a Fenton-type system. The flux of OH. was measured by a spectrofluorimetric assay of salicylate produced by the reaction of benzoate with OH.. Cell damage caused by the OH. generating system was prevented in the presence of catalase, which destroyed H2O2. Damage caused in a standard incubation time increased with increased amounts of glucose oxidase. Protection against OH.-mediated cell damage increased with increasing concentration of HA. The presence of HA did not interfere with the enzyme-Fenton system, as monitored by production of gluconate. On the other hand, HA scavenged OH. produced by the enzyme-Fenton system, as shown by competition with benzoate, which produced less salicylate in the spectrofluorimetric assay in the presence of HA. The reaction of OH. with HA was measured directly by a pulse radiolysis technique in which a hydrated electron (eaq-) produced OH. by the reaction with nitrous oxide. Second order rate constants obtained in distilled H2O or in phosphate buffer showed no dependence on HA M(r). Similarly, fluorimetric assay of the flux of in the enzyme-Fenton system confirmed that HA competed with benzoate, thus lowering salicylate production, and the flux was also independent of the molecular mass of HA.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of smoke inhalation on alveolar surfactant subtypes in mice

The effects of smoke inhalation on alveolar surfactant subtypes were examined in mice exposed for 30 minutes to smoke generated from the burning of a flexible polyurethane foam. At 4 or 12 hours after the exposure, three surfactant pellets, P10, P60, and P100, and a supernatant, S100, were prepared by sequential centrifugation of lavage fluids at 10,000 g for 30 minutes (P10), 60,000 g for 60 minutes (P60), and 100,000 g for 15 hours (P100 and S100). Phospholipid analysis and electron microscopy were performed on each fraction. Smoke exposure dramatically altered the normal distributions of these fractions: it significantly increased the phospholipid content of the heavier subtype, P10, which is thought to represent newly secreted surfactant; had no effect on the intermediate form, P60; and dramatically increased the phospholipid content (approximately fivefold) of the lighter subtypes, P100 and S100, which are believed to represent catabolic end-products of alveolar surfactant. Only P100 was structurally altered by the smoke. These results represent alterations of the normal metabolic processing of alveolar surfactant. Whereas the mechanism is yet to be defined, it seems to involve a small but significant increase in the newly secreted surfactant, as well as an excessively high accumulation of the structurally altered catabolic forms of the secreted surfactant.

Trichloroethylene-induced pneumotoxicity in fetal and neonatal mice

Trichloroethylene (TCE) has previously been shown, in adult mouse lung, to alter the distribution of phospholipid associated with the pulmonary surfactant and to affect the activity of phospholipase A2, an enzyme involved in synthesis of the surfactant. However there are no data available on the effects of maternal exposure to TCE on fetal lung development. To determine if maternal TCE exposure may affect fetal pulmonary development, pregnant mice were treated with TCE (3000 mg/kg body wt.) administered intraperitoneally on day 17 of pregnancy. Fetuses were examined on the 18th and 19th gestational days and the 1st, 5th and 10th postnatal days. TCE caused increased mortality among 18- and 19-day-old fetuses and 1-day-old newborn mice. In addition mean body weight was reduced on the 1st postnatal day in animals exposed to TCE. Specific lung weights were also significantly reduced on both the 18th and 19th gestational days. More importantly, total lung phospholipid content was depressed immediately before birth; total DNA was not affected. These results suggest that prenatal maternal exposure to TCE may delay pulmonary maturation during the critical period when surfactant synthesis is initiated.

Stimulation of signal transduction pathways in osteoblasts by mechanical strain potentiated by parathyroid hormone

Second-messenger systems have been implicated to transmit mechanical stimulation into cellular signals; however, there is no information on how mechanical stimulation is affected by such systemic factors as parathyroid hormone (PTH). Regulation of adenylyl cyclase and phosphatidylinositol pathways in rat dentoalveolar bone cells by mechanical strain and PTH was investigated. Two different cell populations were isolated after sequential enzyme digestions from dentoalveolar bone (group I and group II) to study potential differences in response. Mechanical strain was applied with 20 kPa of vacuum intermittently at 0.05 Hz for periods of 0.5, 1, 5, 10, and 30 minutes and 1, 3, and 7 days using the Flexercell system. Levels of cAMP, measured by RIA, and levels of inositol 1,4,5-triphosphate (IP3) and protein kinase C activity (PKC), measured by assay systems, increased with mechanical strain. When PTH was added to the cells, there was a significant increase in levels of all the intracellular signals, which appeared to potentiate the response to mechanical strain. IP3 levels (0.5 minute) peaked before those of PKC activity (5 minutes), which in turn peaked before those of cAMP (10 minutes). Group II cells showed higher levels of cAMP and IP3 than the group I cells. This suggests that the former may ultimately play the predominant roles in skeletal remodeling in response to strain. Immunolocalization of the cytoskeleton proteins vimentin and alpha-actinin, focal contact protein vinculin, and PKC showed a marked difference between strained and nonstrained cells. However, the addition of PTH did not cause any significant effect in cytoskeleton reorganization. Staining of PKC and vimentin, alpha-actinin, and vinculin suggests that PKC participates actively in the transduction of mechanical signals to the cell through focal adhesions and the cytoskeleton, although only PKC seemed to change with short time periods of strain. In conclusion, dentoalveolar osteoblasts responded to mechanical strain initially through increases in levels of IP3, PKC activity, and later cAMP, and this response was potentiated when PTH was applied together with mechanical strain.

Case report: the antenatal ultrasound diagnosis of megalourethra

The antenatal ultrasound findings in a fetus which postnatally had fusiform megalourethra, rectal agenesis, recto-vesical fistula and unilateral renal hypoplasia are described. At 16 weeks gestation a cystic area was seen arising from the perineum. It later became evident that this was the urethra. Initially, an echogenic mass was noted in the pelvis, but by the second trimester, fluid-filled loops of bowel were evident. This combination of developmental abnormalities though rare is well defined. Only one previously recorded case has been suspected antenatally.

Influence of protein kinase C activation by 4 beta-phorbol ester or 1-oleoyl-2-acetylglycerol on disaturated phosphatidylcholine synthesis and secretion, and protein phosphorylation in differentiating fetal rabbit type II alveolar cells

Undifferentiated type II alveolar cells were isolated from the fetal rabbit lung on the 24th gestational day, grown in vitro for 2-3 days, and used to test the hypothesis that activation of protein kinase C by 4 beta-phorbol ester (TPA) or the diacylglycerol analogue, sn-1-oleoyl-2-acetylglycerol (OAG), stimulates disaturated phosphatidylcholine (DSPC) synthesis and secretion. To measure secretion, cells were prelabelled with [3H]choline in serum-free medium or medium with 10% carbon-stripped fetal bovine serum for 24 h. The radiolabel was removed and TPA (10(-6)-10(-9) M) or OAG (125, 250 or 500 microM) was incubated with the cells for 2 h. The medium was removed and filtered. Fresh medium with the same compound was added for an additional 16 h. To measure synthesis, cells were incubated with [3H]choline and concurrently TPA or OAG was added. Cells were removed at 2 or 18 h. After 2 h at concentrations of 10(-8) M, TPA augmented the release of 3H-labelled DSPC, the major component of the surfactant, by cells incubated in serum-free medium. In the presence of carbon-stripped fetal bovine serum, TPA (10(-7) and 10(-6) M) induced release of DSPC. The incorporation of [3H]choline into intracellular DSPC was increased after 2 or 18 h in fetal alveolar cells exposed to TPA at 10(-9) M or higher. OAG also significantly significantly stimulated the release of labelled DSPC after 2 h at all concentrations tested. In contrast, OAG-exposed cells displayed a reduction of [3H]choline incorporation into cellular DSPC. Characterization of radioactive material released by prelabelled fetal type II cells showed that phorbol ester stimulation increased the release of material which co-migrated with adult rabbit lung lamellar bodies on a sucrose gradient. Electrophoretic examination of [gamma-32P]ATP phosphorylation sites in fetal type II cells cells showed that TPA and OAG induced an increase in phosphorylation of a group of proteins with apparent molecular masses of 45, 50 and 55 kDa. Addition of phosphatidylserine to the incubations produced substantial increase in the phosphorylation of these proteins, particularly in the presence of TPA. Fetal type II cells also displayed a phosphorylation product with an apparent molecular mass of 97 kDa. This protein as well as two high-molecular-mass products appeared to be particular to cells incubated with TPA plus phosphatidylserine and may in part account for the different action of TPA compared to OAG with regard to synthesis and secretion of DSPC by the fetal type II cells.

Molecular modelling of secondary and tertiary structures of hyaluronan, compared with electron microscopy and NMR data. Possible sheets and tubular structures in aqueous solution

Electron microscopy shows that hyaluronan (HA) forms sheets and tube-like structures in solution. Molecular modelling by Tartu plastic space-filling atomic models revealed that hydroxymethyl and carboxylate groups of HA anti-parallel chains can be joined by H-bonds. Using these bonds, HA molecules can be modelled as sheets and tubules. These tertiary structures have three kinds of lateral contact: (1) antiparallel chains stacked by hydrophobic patches; (2) parallel chains joined by both stacking interactions and H-bonds; and (3) crossing chains joined by H-bonds and stacking interactions. Sheet and tubular structures may explain some viscoelastic and biological properties of HA.

Keratan sulphate--a 'reserve' polysaccharide?

The early history of keratan sulphate and its proteoglycans is briefly described. Studies were overlooked that could have had a profound influence on later work. Early methods of writing the structures of keratan and chondroitin sulphates obscured the fundamental relationships between them. Both are now seen to be based on the same polymer backbone poly(Gal beta 1:4 Glc beta 1-3). Confusion over the complicated sulphation patterns in keratan sulphate was clarified by the domain structure idea by the group of Helmut Greiling. Keratan sulphate is characteristic of avascular tissues (cartilages, intervertebral discs, corneal stromas) that get their oxygen supplies by diffusion. Stockwell's early idea that the distribution of keratan sulphate in cartilages was a response to the poor supply of oxygen has been generalised, to the hypothesis that keratan sulphate is a functional substitute for chondroitin sulphate under conditions of oxygen lack. The keratan:chondroitin sulphate ratios in discs, corneas of different species, and changes therein with age can be explained on this basis. The biochemical controlling step is probably the NAD:NADH ratio. Keratan sulphate may thus be a 'reserve' polysaccharide, able to do the job of chondroitin sulphate in adverse conditions of oxygen supply. Keratan and chondroitin/dermatan sulphates have similar functions in corneal stroma, and probably in the other connective tissues in which they are found. They swell the collagenous matrix, keeping the fibrils apart. Even more importantly, they probably act as tissue organisers, orienting the fibrils vis-a-vis each other via specific interactions of their proteoglycan protein cores with the fibrils.(ABSTRACT TRUNCATED AT 250 WORDS)

On the polylactose nature of chondroitin and keratan sulphates

The recognition that keratan and chondroitin sulphates are based on the same polylactose backbone simplifies the study of heteroduplex formation between them, suggests insights into structure-function relationships in tissues, and permits new definitions of the linkage regions.

The chemical morphology of age-related changes in human intervertebral disc glycosaminoglycans from cervical, thoracic and lumbar nucleus pulposus and annulus fibrosus

Hyaluronan (HA), chondroitin and keratan sulphates (CS, KS), collagen and dry weights were measured in the annulus fibrosus and nucleus pulposus of human cervical, thoracic and lumbar intervertebral discs aged 36-79 y. Alcian blue-critical electrolyte concentration (CEC) staining of sections extended the results. The collagen, total polyanion, HA, CS and KS contents of the nucleus pulposus and annulus fibrosus were plotted for all 3 regions against age. Regional differences and age-related trends were found. For regional differences, the collagen content of the nucleus pulposus was highest in cervical discs and lowest in lumbar discs. In contrast, the total polyanion content of the nucleus pulposus was highest in lumbar discs and lowest in cervical discs. These differences were seen in fetal and adult discs. With respect to age-related trends, the collagen content of the annulus fibrosus was higher in adults and children than in neonates and infants. The collagen content of the nucleus pulposus increased with age in thoracic and lumbar discs, but it was consistently high in cervical discs. There was generally a downward trend of total polyanion and CS with increase in age. This was quite consistent for the annulus fibrosus in all regions and there were dramatic decreases in the lumbar nucleus pulposus in all adults compared with infants and children. These trends were least evident in the cervical nucleus pulposus where infant values were low. CS changes correlated with water content. HA and KS increased in all discs with increasing maturity. Oversulphated KS, absent from fetal discs, reached mature levels by 10 y. Many of the changes occurred before maturity. Glycosaminoglycan (GAG) levels correlated with increasing compressive loads. Higher collagen levels in the cervical nucleus pulposus correlated with greater ranges of torsional and shearing strains in cervical discs. High GAG levels in cervical annulus fibrosus probably facilitate lamellar movements during torsional and flexional movements by lubrication and increase of tissue compressibility. Increased KS/CS ratios before maturity correlated with decreased disc blood supply. Ambient O2 tensions may determine KS/CS balance, the former consuming little O2 during biosynthesis.

The chemical morphology of extracellular matrix in experimental rat liver fibrosis resembles that of normal developing connective tissue

The time course of development of extracellular matrix (ECM) in experimentally induced fibrosis (thioacetamide administration followed for 12 weeks or bile duct ligation for 8 weeks) in adult rats was examined by light and electron microscopy, using Alcian blue or Cupromeronic blue staining for sulphated proteoglycans (PGs) in critical electrolyte concentration techniques. Proteodermatan sulphate (PDS) was regularly observed at the gap zone of the collagen fibrils. Morphometry of uranyl acetate-stained collagen fibrils, polarity of their banding patterns (a-e), statistics of d/e band occupancies by PDS, and lengths and thicknesses of PG filaments were quantified. Biochemical analyses showed that the ECM components collagen, hyaluronan, chondroitin and dermatan sulphates increased by 5-10 fold, roughly in parallel, as did heparan sulphate and DNA. Water and lipid contents also increased sharply. Thioacetamide treatment was much slower than bile duct ligation in producing fibrotic changes of equal severity. Sulphation of anionic glycosaminoglycans (AGAGs) decreased with increasing severity of fibrosis. Biochemical and ultrastructural methods correlated well. The large increase in dermatan sulphate was quantitatively as expected, given that it is collagen fibril surface-associated, and there was an increase of collagen content together with a decrease in fibril thicknesses. The increase in DNA reflected the marked increase in cell numbers in fibrotic livers. The chemical morphology of the new connective tissue closely resembled that in e.g. developing young tendon, in that fibrils were thinner, and AGAG levels were higher. The collagen fibrils were often disarranged, rather than ordered and parallel as in normal ECM. No other indication of abnormality in the new ECM was obtained.

Perinatal lung development following maternal exposure to methylmercuric chloride

Mercury ingested from dietary sources has potent neurotoxic and teratogenic effects. Initial studies have shown that mercury may also affect fetal lung development. Since these pulmonary effects may play a role in subsequent neonatal morbidity and mortality due to compromising of the development of the lung, mercury effects in fetal and neonatal lung were investigated. Methylmercuric chloride (MMC), 1,000 ppm (15 mg/kg of body weight); was administered via an intragastric tube to timed-pregnant Swiss/Webster mice on day 9 of gestation. Lungs from fetuses on gestational day 18 and from neonates on days 1, 5, or 10 after birth were studied. Significant changes in MMC-exposed lungs compared to controls occurred at postnatal day 1. At this time, lung weight per gram body weight increased, phospholipid content per gram of lung or per microgram of DNA decreased, while DNA per gram of lung increased. Methylmercury appears to have delayed lung maturation. Cuboidal epithelial cells in alveolar tubules contained conspicuous glycogen deposits, and differentiation of alveolar type II cells was adversely affected. These results suggest that prenatal exposure to methylmercury may be detrimental to lung development, specifically to the initiation of surfactant synthesis, by delaying the normal pattern of maturation of the alveolar type II cells within the lungs.

Distribution and characteristics of Ca+2-phosphatidylserine-dependent protein kinase C in subcellular fractions and lamellar bodies of adult rabbit lung

Pulmonary surfactant prevents lung collapse at minimal alveolar diameter. Since surfactant acts extracellularly, secretion is vitally important in regulating the alveolar surfactant levels. Studies with phorbol esters which stimulate protein kinase C (PKC) activity suggest PKC is involved in regulating surfactant secretion. This study was done to characterize PKC activity in adult rabbit lung fractions. Lungs were removed, homogenized and subcellular fractions prepared by centrifugation on a discontinuous sucrose gradient. Calcium-phosphatidylserine-dependent PKC activity was assayed in fractions in the presence of 4 microM phorbol 12-myristate 13-acetate, 1mM EDTA, 8 mole% phosphatidylserine and 1mM Ca2+ by measuring the transfer of 32P from [gamma-32P]ATP to protein. Concurrent assays were done without Ca+2 or PS. Ca+2-PS dependent PKC activity was defined as the difference between the two. Select fractions were incubated with PKC inhibitors sangivamycin, acridine orange or 9-aminoacridine and activity measured. The results showed the majority of the PKC activity was in the cytosolic fraction (87%, specific activity, 142 pmoles/min/mg) but the lamellar bodies also appeared to contain a small amount of PKC activity (approximately 4.0%, 151 pmoles/min/mg). PKC inhibitors were used to examine the characteristics of the enzyme in the microsomal and lamellar body fractions. Sangivamycin was the most potent inhibitor. Some differences in the inhibition characteristics between the lamellar body and microsomal fractions were observed. However using an add-back approach with the lamellar body fraction, indicated that the small quantity of activity in this fraction be attributed to contamination by microsomes. These results indicate that PKC is active in adult rabbit lung subcellular compartments but is probably not associated with the intracellular surfactant storage organelles.

The nomenclature of glycosaminoglycans and proteoglycans

1. The proposed terms and codes provide concise, quantitative information on the polymer backbone, state of oxidation, patterns of sulphation and epimerization, and proportions of monomeric units. Oversulphated domains and special units are easily recognized. 2. They are intermediate between general statements (e.g. 'chondroitin sulphate') and detailed primary structures. 3. They bring terminology into line with current analytical techniques, which depend largely on enzymes developed by S. Suzuki and co-workers. Current enzyme nomenclature (chondroitinase ABC, AC) can still be used. 4. They are not primarily intended to be spoken, although some codes are easily articulated. 5. They have capacity and flexibility to accommodate future developments.

A phase II and pharmacokinetic study with oral piritrexim for metastatic breast cancer

Piritrexim is a lipid-soluble antifolate which, like methotrexate, has a potent capacity to inhibit dihydrofolate reductase. We performed a multicentre phase II study with piritrexim in patients with locally advanced or metastatic breast cancer. Twenty-four patients of which sixteen had received prior chemotherapy, were initially treated with 25 mg piritrexim orally administered trice daily for four days, repeated weekly, with provision for dose escalation or reduction according to observed toxicity. Of twenty-one patients evaluable for tumour response, one patient achieved a partial response which lasted for 24 weeks. Three patients had stable disease during 12 weeks of treatment, seventeen had progressive disease. Pirtrexim was generally well tolerated, in eighteen patients the dose could be escalated. Myelotoxicity was the most frequent observed toxicity of this piritrexim regimen. Leucopenia and thrombocytopenia grade 3/4 occurred in 38% of the patients sometime during treatment. Pharmacokinetic analysis of piritrexim in three patients during the first treatment cycle, revealed peak levels 1 to 2 h after an oral dose, with a trend towards a higher peak plasma levels and AUCs on the fourth dosing day compared with the first dosing day. In conclusion, orally administered piritrexim appears to be a regimen with little activity in patients with locally advanced or metastatic breast carcinoma.

Ultrastructural and biochemical observations on proteoglycans and collagen in the mutable connective tissue of the feather star Antedon bifida (Echinodermata, Crinoidea)

Mutable connective tissue, unique to echinoderms, changes its mechanical behaviour within seconds of nervous stimulation. The molecular mechanism of this phenomenon is not understood. In this study proteoglycans and collagen of the brachial ligaments connecting neighbouring ossicles of the arms of the feather star Antedon bifida have been investigated by biochemistry, light and electron microscopy and the critical electrolyte concentration (CEC) technique using the dye Cupromeronic Blue (CB). The ligaments consist mainly of parallel cross-striated collagen fibrils, 82 +/- 12 nm in diameter, with a characteristic banding pattern and a D-period of 52.8 +/- 3.2 nm. Some fibrils were disaggregated into bundles of 10-11 nm protofibrils, lying between the normal fibrils. Proteoglycans occur at the surface of the fibrils with 2 binding sites (each with a different CEC) per D-period and also inside the fibrils. The surface proteoglycans are more highly sulphated (i.e. their CECs are > 1.3 M) than the intrafibrillar proteoglycans (CEC < 0.9 M). The glycosaminoglycans consist of a highly sulphated chondroitin sulphate, possibly with fucose residues. The results are consistent with the theory that disaggregation of the fibrils into protofibrils and reaggregation might be a mechanism of mutability, without excluding the possibility that fibrils may slide alongside each other during movements in the viscous phase of the ligament.

Violence and sexual violence in pornography: is it really increasing?

Literature and research on the question of the increasingly violent nature of pornography is reviewed. In addition, the paper reports the findings of a content analysis of all cartoons and pictures in Hustler Magazine from 1974 through 1987. Results indicate that sexually violent cartoons and/or pictorials constitute a relatively small proportion of the total cartoons and pictorials. Moreover, no monotonic increase was found in such depictions over the 14-year period examined. In fact, a relatively small and constant proportion of violent and/or sexually violent depictions over this period is reported. These findings are examined in relation to previous research and societal concern about alleged increases in violent pornography as an explanation for increases in rape rates.

Fetal ureteric reflux: a follow-up study

The findings in 21 children (17 males) with ureteric reflux diagnosed in the first 3 months of life and likely to have been present antenatally are described; 19 were followed up for between 2 and 8 years. Reflux was grade 3 and bilateral in 13 babies. Radioisotope studies showed evidence of renal parenchymal abnormalities in 45% of non-infected refluxing kidneys. Nonoperative treatment was adopted initially. The reflux disappeared completely in 6 children: evidence that it would do so was apparent within 2 years. Two children developed pelviureteric junction obstruction that was secondary to the dilatation accompanying the reflux. Anti-reflux surgery was performed in 10 children because the degree of reflux and upper urinary tract dilatation were increasing. Operative treatment for fetal ureteric reflux of advanced grades should be considered if there is no improvement after 2 years; gigantic reflux may otherwise ensue.

Influence of strain on [3H]thymidine incorporation, surfactant-related phospholipid synthesis, and cAMP levels in fetal type II alveolar cells

Episodic fetal breathing movements occur in utero; however, their purpose is not known. While some evidence indicates these movements produce distention of the fetal lung, the effects of eliminating the movements on lung development are not clear. Using preparations of the surfactant-producing fetal rabbit lung type II cells, we have examined the hypothesis that distention is involved in maturation of these cells as determined by replication rate and phospholipid synthesis. Differentiating type II cells were isolated from fetal rabbit lungs on gestational day 24. After allowing 24 h for the cells to attach, distention (10%) was applied using a Flexercell apparatus at a rate of 3 s of strain and 57 s of rest for 24 or 48 h. Cells were concurrently incubated with [3H]thymidine. Autoradiography showed that [3H]thymidine-labeled nuclei of fetal type II cells and fibroblasts could be identified. Strain significantly increased incorporation of the radioisotope into DNA. In the remaining studies, cells were grown to confluence prior to use. Cell viability after straining (3 or 50 cycles per minute [cpm] for 48 h) was assessed by incubating with diacetyl fluorescein/ethidium bromide and viewing by fluorescence microscopy. Straining did not alter cellular viability. Lactate dehydrogenase was also assayed in the culture medium. Straining did not cause release of lactate dehydrogenase. Ultrastructural examination showed typical cellular appearance in the strained cells. Extracellular lamellar body material was also observed. The incorporation of [3H]choline (3 or 50 cpm) into cellular phospholipids was measured under static conditions or under distention. [3H]choline-labeling of phosphatidylcholine and disaturated phosphatidylcholine was significantly increased by distention at either 3 or 50 cpm.(ABSTRACT TRUNCATED AT 250 WORDS)