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R M Mason

Publications and source records attributed to R M Mason.

At least 55 records · Page 3Linked to original sources
PubMed1999

Cloning and characterization of ZNF236, a glucose-regulated Kruppel-like zinc-finger gene mapping to human chromosome 18q22-q23.

We report the cDNA cloning and characterization of ZNF236, a novel Kruppel-like zinc-finger gene initially identified by its glucose-regulated expression in human mesangial cells using mRNA differential display. Using the differential display fragment as a probe, we screened a human fetal kidney cDNA library and isolated several clones representing two differently spliced mRNA transcripts, designated ZNF236a and -b. Both transcripts were identical apart from the presence of an additional exon in ZNF236a that truncates the open reading frame. RT-PCR analysis confirmed the expression of both transcripts to be upregulated in human mesangial cells in response to elevated levels of d-glucose. ZNF236a and -b cDNAs encode polypeptides of 174 and 204 kDa, containing 25 and 30 C(2)H(2) zinc-finger motifs, respectively. Northern blot analysis showed that ZNF236 is ubiquitously expressed in all human tissues tested. Expression levels were highest in skeletal muscle and brain, intermediate in heart, pancreas, and placenta, and lowest in kidney, liver, and lung. Southern zoo blot analysis indicated that ZNF236 is conserved in the genomes of all mammalian species tested, but not in yeast. The mapping of ZNF236 to human chromosome 18q22-q23, close to the IDDM6 locus, coupled with the glucose-regulated expression of the gene in human mesangial cells, suggests that ZNF236 may be a candidate gene for diabetic nephropathy.

Adult↗
PubMed1999

Characterization of the effect of high molecular weight hyaluronan on trans-synovial flow in rabbit knees.

1. The effect of a rooster comb hyaluronan (3.6-4.0 g l-1) of similar chain length to rabbit synovial fluid hyaluronan, on the trans-synovial escape of fluid from the joint cavity in the steady state ( 8d s) was studied in 29 rabbit knees at controlled intra-articular pressures (Pj). 2. Rooster hyaluronan caused the pressure-flow relation to flatten out as pressure was raised. At 10-20 cmH2O the slope of the quasi-plateau, 0.05 +/- 0.01 microliter min-1 cmH2O-1 (mean +/- s.e.m.), was 1/39th that for Ringer solution (1.94 +/- 0.01 microliter 2O-1 ). 3. Bovine synovial fluid had a similar effect to hyaluronan in Ringer solution. 4. The quasi-plateau was caused by increasing opposition to outflow; the pressure required to drive unit outflow increased 4.4-fold between 5 and 20 cmH2O. The increased opposition to outflow at 20 cmH2O was equivalent to an effective osmotic pressure of 13-17 cmH2O at the interface. Since the infusate's osmotic pressure was only 0.9 cmH2O, this implied concentration polarization to 15-18 g l-1 hyaluronan at the interface. 5. Mechanical perforation of the lining, or enzymatic degradation of the interstitial matrix by chymopapain, abolished the quasi-plateau. Hydrational expansion of the matrix by approximately 2-fold did not. The increased opposition to outflow was reversible by washing out the hyaluronan, or by reducing Pj. It was unaffected by interruption of tissue blood flow or synoviocyte oxidative metabolism. These properties are compatible with a concentration polarization mechanism, i.e. flow-induced concentration of hyaluronan at the synovial interface due to molecular reflection. 6. A concentration polarization theory was developed for a partially reflected solute. Numerical solutions supported the feasibility of this osmotic explanation of the quasi-plateau. Additional mechanisms may also be involved. 7. It is concluded that native-size hyaluronan helps to retain synovial fluid in the joint cavity when pressure is raised and acts, at least in part, by exerting osmotic pressure at the interface between synovial matrix and a concentration polarization layer.

Animals↗
PubMed1999

Chondroitin sulphation patterns in synovial fluid in osteoarthritis subsets.

OBJECTIVES: To determine concentrations of chondroitin sulphate (CS) disaccharides in knee synovial fluid (SF) from normal subjects and patients with osteoarthritis (OA) or rheumatoid arthritis (RA), to test whether these variables differ between different diseases and subsets of OA. METHODS: OA was subdivided into large joint OA (LJOA), nodal generalised OA (NGOA), and OA with calcium pyrophosphate crystal deposition (CPA), with 25, 9, and 11 people in each subset respectively. The SF of 13 normal subjects was also volunteered for analysis along with 15 RA patients. Clinical assessment of inflammation (0-6) was undertaken on OA and RA knees. Concentrations of unsaturated CS disaccharides Deltadi6S and Deltadi4S were measured by capillary zone electrophoresis. RESULTS: Concentrations of Deltadi6S were lower in RA (5.90 ng/ml) and OA (13.24 ng/ml) fluids compared with normal (21.0 ng/ml) but no significant differences were seen between disease and normal fluids for Deltadi4S (about 4-6 ng/ml). The ratio of Deltadi6S:Deltadi4S were RA<OA<normal subjects (p<0.001 for all comparisons). The disaccharide concentration values along with the ratios are below. Higher Deltadi6S:Deltadi4S ratios were obtained for LJOA and CPA compared with NGOA. Uninflamed knees had lower concentrations of Deltadi6S than inflamed knees (p<0.01). In patients with bilateral samples, there were strong correlations between right and left knees for all SF variables. CONCLUSIONS: Altered ratios of CS sulphation patterns occur in OA and within OA subsets. These further justify considering NGOA as a subset with a different aetiopathogenesis.

Adult↗
PubMed1998

A STS content physical and transcription map across the ky, kyphoscoliosis, nonrecombinant region.

The ky mouse mutant exhibits a degenerative muscle disease resulting in chronic deformation of the spinal column. Following a previous report describing the mapping of the ky locus to a small region of mouse chromosome 9 (Skynner et al., 1995, Genomics 25, 207-213), we have now undertaken a positional cloning approach to identify candidate genes for ky. A YAC/BAC contig encompassing the ky locus was constructed comprising 48 YAC clones and 48 newly generated STSs. The results from the combined physical and genetic analyses showed that only two overlapping BAC clones, which together do not exceed 260 kb, span the ky nonrecombinant region. A combination of gene hunting methods on the critical BACs has led to the identification of seven coding fragments, which have been tested for expression. The expression analysis and the position of the coding fragments on the contig suggest their grouping in at least four transcription units. One of these transcription units is expressed exclusively in skeletal muscle, making it a suitable candidate for this muscle defect in the ky mouse.

Animals↗
PubMed1998

Regulation of gene expression by alternative polyadenylation and mRNA instability in hyperglycaemic mesangial cells.

We have used mRNA differential display to identify a novel high-glucose-regulated gene (HGRG-14) in human mesangial cells cultured for up to 21 days in 30 mM d-glucose. The mRNA of HGRG-14 seems to be regulated post-transcriptionally and encodes a small polypeptide of molecular mass 13 kDa. The native protein occurs as a dimer. The recombinant protein is a substrate for casein kinase II kinase. At high glucose concentrations, HGRG-14 protein levels decrease. This correlates with the appearance of a long form of HGRG-14 mRNA under high-glucose conditions. This form has a long 3' untranslated region containing several ATTTA RNA-destabilizing sequences and has a short half-life. A truncated, more stable mRNA that lacks the long 3' untranslated region is produced at 4 mM d-glucose. The switch from the truncated to the long-form transcript is detected within 2 h of exposure to 30 mM d-glucose, indicating that hyperglycaemic conditions have an acute effect on HGRG-14 mRNA processing.

3' Untranslated Regions↗
PubMed1998

Effect of depletion of glycosaminoglycans and non-collagenous proteins on interstitial hydraulic permeability in rabbit synovium.

1. The hydraulic resistance of synovial interstitium helps to retain a lubricating fluid within the joint cavity. The contributions of sulphated glycosaminoglycans to resistance were assessed by selective depletion by chondroitinase ABC, keratanase and heparinases I, II and III in vivo. Also, since glycosaminoglycans do not account fully for the resistance, the contribution of non-collagenous, structural proteins in interstitium was assessed by treatment with chymopapain, a collagen-sparing protease. 2. Ringer solution containing enzyme was injected into the synovial cavity of the knee in anaesthetized rabbits. After >= 30 min the intra-articular pressure was raised and the relation between pressure (Pj) and trans-synovial outflow (Qs) determined. The slope dQs/dPj at low pressures, i.e. below yield pressure, represents the hydraulic conductance of the lining, i.e. 1/resistance. The contralateral joint received Ringer solution without enzyme as a control. Action of enzymes on the tissue was confirmed by histochemical and immunohistochemical studies. 3. Treatment with chondroitinase ABC (5 joints) increased the hydraulic conductance of the lining by 2.3 times (control, 1.34 +/- 0.22 microliter l min-1 cmH2O-1; post-enzyme, 3.11 +/- 0.45 microliter l min-1 cmH2O-1). This was significantly less than the effects of leech, Streptomyces and testicular hyaluronidases, which caused an average 4.7 times increase (P < 0.001, ANOVA). Analogous findings were made above yield pressure. 4. Treatment with keratanase (3 joints) or heparinases I, II and III (3 joints) caused no significant increase in trans-synovial flows or conductance, even though the concentration of heparan sulphate in synovium is higher than that of chondroitin sulphates or hyaluronan. 5. Treatment with chymopapain (7 joints) caused the greatest increases in trans-synovial flow, which exceeded control flow by an order of magnitude in one case. After 0.1 U chymopapain the average conductance was 6.6 times the control conductance below yield pressure. Immunohistochemical studies confirmed that chymopapain treatment removed the synovial proteoglycans. 6. It is concluded that, despite their similar resistivities in vitro, the different glycosaminoglycans do not contribute equally, weight for weight, to interstitial resistance in vivo. Hyaluronan is the dominant glycosaminoglycan governing synovial interstitial resistance. In addition, non-collagenous structural proteins contribute significantly to interstitial resistance.

Animals↗
PubMed1998

Effect of depletion of interstitial hyaluronan on hydraulic conductance in rabbit knee synovium.

1. The hydraulic resistance of the synovial lining to fluid outflow from a joint cavity (Qs) is important for the retention of intra-articular lubricant. The resistance has been attributed in part to extracellular glycosaminoglycans, including hyaluronan and chondroitin sulphates. Increased permeability in joints infused with testicular hyaluronidase, which digests both chondroitin sulphates and hyaluronan, supports this view. In this study the importance of interstitial hyaluronan per se was assessed using leech and Streptomyces hyaluronidases, which degrade only hyaluronan. 2. Ringer solution was infused into the knee joint cavity of anaesthetized rabbits for 30 min, with or without hyaluronidase, after which intra-articular pressure (Pj) was raised and the relation between pressure and outflow determined. 3. Treatment with Streptomyces, leech or testicular hyaluronidases increased the fluid escape rates by similar factors, namely 4- to 6-fold. After Streptomyces hyaluronidase treatment the slope d 8d s/dPj, which at low pressures represents synovial hydraulic conductance, increased from a control of 0.90 +/- 0.20 microl min-1 cmH2O-1 (mean +/- s.e.m. , n = 6) to 4.52 +/- 0.70 microl min-1 cmH2O-1. The slope d 8d s/dPj increased to a similar level after testicular hyaluronidase, namely to 4.14 +/- 1.06 microl min-1 cmH2O-1 (control, 0.54 +/- 0.24 microl min-1 cmH2O-1). Streptomyces and leech hyaluronidases were as effective as testicular hyaluronidase (no statistically significant differences) despite differences in substrate specificity. 4. It was shown using histochemical and immunohistochemical techniques that hyaluronan was removed from the synovium by leech, Streptomyces and testicular hyaluronidases. The binding of antibodies 2-B-6 and 3-B-3 showed that the core proteins of the chondroitin sulphate proteoglycans remained intact after treatment with hyaluronidases, and the binding of 5-D-4 showed that keratan sulphate was unaffected. An azocasein digestion assay confirmed that the hyaluronidase preparations had no significant proteolytic activity. 5. The effect of the hyaluronidases was four times greater than predicted from the low concentration of interstitial hyaluronan and its resistivity. Factors that might amplify the effect of hyaluronan depletion include the matrix-organizing role of hyaluronan, and/or non-uniformity of hyaluronan distribution. It is concluded that interstitial hyaluronan makes a major contribution to synovial hydraulic resistance, but the mechanisms are as yet poorly understood.

Animals↗
PubMed1998

Direct evidence for the partial reflection of hyaluronan molecules by the lining of rabbit knee joints during trans-synovial flow.

1. In synovial joints hydraulic and turnover studies indicate that the synovial lining may partially reflect large macromolecules like hyaluronan, despite discontinuities in the lining cell layer. The reflection hypothesis was tested directly in the present study. 2. Solutions of high molecular weight hyaluronan were infused at controlled pressures into the cavity of rabbit knees under anaesthesia, at concentrations of 0.2 g l-1 (n = 5), 2 g l-1 (n = 5) and 4 g l-1 (n = 6). Time-averaged trans-synovial flows were 9.6, 4. 8 and 2.9 microl min-1, respectively. After 5 h infusion the intra-articular fluid was mixed and sampled. Hyaluronan concentration was determined by size-exclusion chromatography. 3. In all sixteen experiments the hyaluronan concentration in the aspirate was greater than that in the infusate (P = 0.0001, Student's paired t test). The increases averaged 2.28 +/- 0.04 times at high filtration rates (0.2 g l-1 infusates; mean +/- S.E.M.), 1.60 +/- 0. 09 times at intermediate filtration rates (2 g l-1 infusates) and 1. 26 +/- 0.08 times at low filtration rates (4 g l-1 infusates). 4. Between 48 and 95 % of the hyaluronan in the filtrand was retained in the joint cavity. The greater retention at 2 g l-1, viz.95 %, than at 0.2 g l-1, viz.48 %, was attributed to interactions between overlapping molecular domains in the more concentrated solution. 5. It is concluded that synovial interstitial matrix can partially reflect hyaluronan molecules, and thus conserve intra-articular lubricant.

Animals↗
PubMed1998

The proteoglycans and glycosaminoglycan chains of rabbit synovium.

The synovial lining of joint capsules is important because it controls the flow of fluid into and out of the joint cavity. Physiological studies have shown that the glycosaminoglycans, particularly hyaluronan, have an important role in the control of fluid flow. The distribution of the glycosaminoglycans and proteoglycans in the synovium and subsynovium of rabbits (approximately 12 weeks old) was, therefore, determined immunohistochemically. Hyaluronan, chondroitin-4- and chondroitin-6-sulphates and keratan sulphate are present in the synovium and subsynovium; chondroitin-4-sulphate is at higher concentrations than chondroitin-6-sulphate. The core proteins of the chondroitin sulphate proteoglycans, biglycan and decorin, and of the keratan sulphate proteoglycan, fibromodulin, are also present. To date, fibromodulin has not been located in other synovial linings, and its presence corroborates that of keratan sulphate.

Animals↗
PubMed1998

Retrograde trafficking of both Golgi complex and TGN markers to the ER induced by nordihydroguaiaretic acid and cyclofenil diphenol.

Previous studies have shown that the Golgi stack and the trans-Golgi network (TGN) may play a role in capturing escaped resident endoplasmic reticulum (ER) proteins, and directing their retrograde transport back to that organelle. Whether this retrograde movement represents a highly specific or more generalized membrane trafficking pathway is unclear. To better understand both the retrograde and anterograde trafficking pathways of the secretory apparatus, we examined more closely the in vivo effects of two structurally unrelated compounds, the potent lipoxygenase inhibitor nordihydroguaiaretic acid (NDGA), and the non-steroidal estrogen cyclofenil diphenol (CFD), both of which are known to inhibit secretion. In the presence of these compounds, transport of vesicular stomatitis virus G membrane glycoprotein from the ER to the Golgi complex, and from the TGN to the cell surface, was inhibited potently and rapidly. Surprisingly, we found that NDGA and CFD stimulated the rapid, but not concomitant, retrograde movement of both Golgi stack and TGN membrane proteins back to the ER until both organelles were morphologically absent from cells. Both NDGA- and CFD-stimulated TGN and Golgi retrograde membrane trafficking were inhibited by microtubule depolymerizing agents and energy poisons. Removal of NDGA and CFD resulted in the complete, but not concomitant, reformation of both Golgi stacks and their closely associated TGN compartments. These studies suggest that NDGA and CFD unmask a generalized bulk recycling pathway to the ER for both Golgi and TGN membranes and, further, that NDGA and CFD are useful for investigating the molecular mechanisms that control the formation and maintenance of both the Golgi stack proper and the TGN.

Adaptor Proteins, Vesicular Transport↗
PubMed1997

Hyaluronan secretion into the synovial cavity of rabbit knees and comparison with albumin turnover.

1. Hyaluronan is not only a lubricant but also enhances the synovial lining's resistance to fluid outflow. This finding led to the proposal that hyaluronan (> 2 x 10(6) Da, approximately 210 nm radius) may escape across the synovial lining less freely than smaller solutes (e.g. albumin, 6.7 x 10(4) Da, 3.6 nm radius) or water. Here multiple washouts were used to measure intraarticular hyaluronan mass and secretion rate in rabbit knees, leading to an estimate of hyaluronan turnover time. Plasma albumin permeation into the joint cavity was also measured to enable comparison of turnover times between molecules of very disparate size. 2. Endogenous hyaluronan mass in the joint cavity, analysed by high performance liquid chromatography of joint washes, was 182 +/- 9.9 micrograms (mean +/- S.E.M; n = 21). Since hyaluronan concentration in synovial fluid averages 3.62 +/- 0.19 micrograms microliters-1, the endogenous synovial fluid volume was calculated to be 50 microliters (mass/concentration), about double the aspiratable volume. 3. The hyaluronan secretion rate over 4 h was 4.80 +/- 0.77 micrograms h-1 (n = 5). The rate was significantly higher in contralateral joints expanded by 2 ml Ringer solution (5.80 +/- 0.84 micrograms h-1, n = 5, P = 0.01, Student's paired t test), indicating a stretch/hydration sensitive secretory mechanism. The newly secreted chains ((2.05-2.48) x 10(6) Da) were not significantly different in length from the endogenous chains (2.95 x 10(6) Da). 4. Hyaluronan turnover time, calculated as mass/secretion rate, was 31.4-37.9 h. This is more than an order of magnitude longer than turnover time for intra-articular albumin. The latter, determined from the intra-articular albumin mass and plasma-to-cavity permeation rate was 1.8 h (95% confidence intervals 1.2-3.5 h, n = 9). The big difference in turnover times support the view that, relative to albumin and water, hyaluronan is partially sieved out and retained in the joint cavity by the synovial lining. The lining cell layer is discontinuous, so it appears that interstitial matrix itself acts as a leaky size-selective molecular filter.

Animals↗
PubMed1997

Identification of glucose-regulated genes in human mesangial cells by mRNA differential display.

Diabetic nephropathy is characterised by an accumulation of extracellular matrix proteins in the glomerular mesangium. Hyperglycaemia is a major factor promoting this progressive expansion of the mesangial matrix. We have used the technique of mRNA differential display to investigate changes in gene expression in cultured human mesangial cells following long-term (21 days) exposure to either physiologic (4 mM) or pathologic (30 mM) D-glucose concentrations. Approximately 12,000 mRNA species were screened for evidence of altered expression and several hundred candidate cDNA fragments were obtained. Northern blot and RT-PCR analysis of ten randomly chosen candidate cDNA fragments revealed three exhibiting increased mRNA expression under elevated D-glucose levels. Nucleotide sequence analysis identified two of the cDNA fragments as encoding prolyl 4-hydroxylase alpha-subunit and thrombospondin-1. The third cDNA fragment represents a novel glucose-regulated gene, encoding a putative zinc finger protein. Upregulated expression of these genes in response to high levels of D-glucose may contribute significantly to the disease process. mRNA differential display is a useful tool to investigate the mechanism of diabetic nephropathy.

Adult↗
PubMed1997

Elevated aggrecan mRNA in early murine osteoarthritis.

Male STR/ort mice develop osteoarthritis in the tibial articular cartilage. Low grade histological lesions first appear between 10-20 weeks of age. A previous study showed that the level of aggrecan, the major cartilage proteoglycan, is approximately twofold greater in the tibial cartilage of 16-19-week-old STR/ort mice compared with that in normal cartilage in control CBA mice. In the present investigation aggrecan gene transcription was investigated in 20-week-old STR/ort and CBA tibial cartilage using a quantitative reverse transcription-polymerase chain reaction (RT-PCR). The amount of aggrecan cDNA obtained from the STR/ort medial and lateral plateau was 2.8- and 4.6-fold greater per milligram of wet cartilage than that from the CBA tibial plateau. The difference was not due to differences in cellularity of tibial cartilage in the two strains and indicates that aggrecan gene transcription is elevated in early osteoarthritis.

Aggrecans↗
PubMed1997

Chondrocyte cytokine and growth factor expression in murine osteoarthritis.

Eighty-five percent of male STR/ort mice develop osteoarthritic lesions of the knee joint by 35 weeks of age. We have developed a non-radioactive in-situ hybridization method using digoxigenin-labeled oligonucleotide probes to study the expression of the cytokines interleukin (IL) 1 alpha, Il-1 beta and IL-6 and the growth factors insulin-like growth factor-1 (IGF-1) and transforming growth factor beta (TGF beta 1) during the development of osteoarthritis (OA) in this model. Age- and sex-matched CBA mice, which do not develop OA, showed no detectable expression of any of the cytokines or growth factors studied. In contrast, 20-week-old STR/ort mice with no OA lesions showed positive expression [positive: (+)] for all the cytokines and growth factors studied. At 35 weeks of age, STR/ort mice with varying grades of OA showed positive (+) or strong (++) signals for both cytokines and growth factors throughout the tibial articular cartilage. The strongest signal was seen in areas where OA lesions were present. In areas of histologically-normal cartilage adjacent to the lesions, the signals were still positive but weaker. Fifty-week-old STR/ort mice with OA lesions showed a similar pattern of expression to 35-week-old mice. Thirty-five or 50-week-old STR/ort mice with no OA lesions had much reduced expression compared with those with OA lesions. These mice may be indicative of those STR/ort mice which do not develop OA. The results seen in the STR/ort together with previous biochemical analyses are consistent with an up-regulation of anabolic growth factors and catabolic cytokines in the prelesional stages of OA with anabolic effects predominating. At later stages of OA, the effects of catabolic factors appear to predominate and osteoarthritic lesions become evident.

Aging↗
PubMed1997

Glycosaminoglycan depletion greatly raises the hydraulic permeability of rabbit joint synovial lining.

The hydraulic resistance of the synovial lining of a joint is important for retention of intraarticular lubricant. The resistance has been attributed to synovial interstitial glycosaminoglycans. This was tested by depletion of hyaluronan and chondroitin sulphates from synovium in five rabbit knees in vivo under anaesthesia, using testicular hyaluronidase. The enzyme raised synovial permeability to fluid 5- to 7-fold-substantially more, in fact, than predicted by a recent model. The results prove that hyaluronan and/or chondroitin sulphate are important sources of hydraulic resistance in synovium.

Animals↗
PubMed1997

Dementia drug development: use of information systems to harmonize global drug development.

Dementia is a worldwide problem with regional differences in distribution. In North America and Western Europe, it is estimated that approximately 70 percent of all cases of dementia are caused by Alzheimer's disease (AD) and 15 percent by vascular dementia. Infectious and metabolic causes of chronic cognitive impairment are more common than AD in developing countries, but as the populations of these countries continue to age rapidly, the problem of age-related dementias such as AD will become enormous. Around the world, numerous medications have been approved for the treatment of dementia, although relatively few have been approved specifically for AD. In Japan, for example, over 20 medications have been approved, primarily for the treatment of vascular dementia, but they are also used for other dementias. Most of these drugs would not meet current standards for efficacy (i.e., Food and Drug Administration or European Union proposed guidelines, or de facto standards set by the approval of tacrine), although most are safe. Similarly, in Europe there are wide variations in available drugs, and many might not be approved if introduced today. This article discusses the International Working Group for the Harmonization of Dementia Drug Guidelines, a collaborative effort to develop safe, effective treatments for dementia by promoting harmonization of regulatory guidelines and multisite, multinational studies to produce global dossiers. It focuses on the use of information systems to achieve this goal.

Dementia↗