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Biomedical subjects

R W Mason

Publications and source records attributed to R W Mason.

At least 73 records · Page 4Linked to original sources
PubMed1986

Cathepsin L inactivates alpha 1-proteinase inhibitor by cleavage in the reactive site region.

The lysosomal cysteine proteinases cathepsin L and cathepsin B were examined for their effect on the neutrophil elastase inhibitory activity of human alpha 1-proteinase inhibitor (alpha 1PI). Human cathepsin L catalytically inactivated human alpha 1PI by cleavage of the bonds Glu354-Ala355 and Met358-Ser359 (the serine proteinase inhibitory site). Cathepsin B did not inactivate alpha 1PI, even when equimolar amounts of enzyme were employed. Cathepsin L is the first human proteinase shown to catalytically inactivate alpha 1PI. These findings, in conjunction with other reports, suggest that alpha 1PI contains a proteolytically sensitive region encompassing residues 350-358. Taken together with the discovery of the elastinolytic activity of cathepsin L (Mason, R. W., Johnson, D. A., Barrett, A. J., and Chapman, H. A. (1986) Biochem. J. 233, 925-927), the present findings emphasize the possible importance of cathepsin L in the pathological proteolysis of elastin and diminish the role that can be attributed to cathepsin B in such processes.

Binding Sites↗
PubMed1986

Elastinolytic activity of human cathepsin L.

The hydrolysis of a tritiated elastin substrate by the human cysteine proteinases cathepsins B and L has been studied. Cathepsin L was found to be at least 100-fold more active on this substrate than cathepsin B. The specific activity of cathepsin L at pH 5.5 for hydrolysis of elastin was about the same as that of pig pancreatic elastase at its optimum pH of 8.8.

Cathepsin L↗
PubMed1986

Distribution of Pt in the urine and kidney of the cisplatin treated rat.

The urinary and renal distribution of Pt following the administration of cis-dichlorodiammine platinum II (cisplatin) to adult male Wistar rats was studied by gel filtration and ion exchange chromatography. Several low molecular weight (LMW) Pt-containing fractions with the same chromatographic properties as those found in urine incubated with cisplatin are present in the kidney cytosol within 15 min of the administration of cisplatin. The concentration of Pt in these fractions decreases rapidly and after 4 h most of the Pt in the kidney cytosol is in a high molecular weight (HMW) fraction which contains 2 subfractions. The smaller fraction (mol. wt. = 20 000), but not the larger (mol. wt greater than 250 000), is also present in the urine of the cisplatin-treated rat, but neither fraction is present in urine incubated with cisplatin and neither is formed by the interaction of cisplatin or the urinary LMW Pt-containing fractions with kidney cytosol in vitro. It is suggested that the smaller fraction may be derived from the filtration and reabsorption of plasma protein-bound Pt, whereas the larger fraction is more likely to be formed exclusively within the kidney cell.

Animals↗
PubMed1986

Species variations amongst lysosomal cysteine proteinases.

Cathepsin B was purified from rabbit, human, ox and sheep liver. SDS-polyacrylamide gel electrophoresis after reaction of the purified cathepsin B samples with the active site directed inhibitor, L-3-carboxy-trans-2,3-epoxypropionyl-leucylamido- ([3H]acetamido)-butane ([3H]Ac-Ep-459), showed that the enzyme exists as either a two-chain form (approx. Mr 25,000 and 4,000), a single-chain form (approx. Mr 30,000) or both. The active site was found in the light chain of the two-chain forms. The two-chain and single-chain forms of ox cathepsin B were separated by ion exchange chromatography and shown to have similar catalytic activities against the substrates Z-Phe-Arg-4-methyl-7-coumarylamide (Z-Phe-Arg-NHMec) and Z-Arg-Arg-NHMec and rates of inhibition by L-3-carboxy-trans-2,3-epoxypropionyl-leucylamido-(4- guanidino)butane (E-64). Cathepsin L was purified from the same four species, and compared with the enzyme from rat liver. SDS-polyacrylamide gel electrophoresis after reaction of the purified cathepsin L preparations with the active site directed inhibitor, [3H]Ac-Ep-459, showed that cathepsin L from each species consists of two chains; a light chain of approx. Mr 5,000 and a heavy chain of approx. Mr 25,000, which contained the active site cysteine. All species variants of cathepsin L were recognized by the antibody to the human enzyme. With Z-Phe-Arg-NHMec as substrate, kinetic constants were found to be similar for all five species (Km 1-4 microM and and kcat 10-30 s-1).(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1985

Human liver cathepsin L.

Cathepsin L was purified to apparent homogeneity from human liver obtained post mortem. It was necessary to treat the homogenate at pH 4.2 and 37 degrees C to release active enzyme. The purification procedure involved ion-exchange chromatography on carboxymethyl-Sephadex and the Mono S column of a Pharmacia fast-protein-liquid-chromatography system. The enzyme was found to consist of two polypeptide chains of Mr 25 000 and 5000. The larger chain was shown to contain the active-site cysteine residue. Human cathepsin L proved to be similar to the rat and rabbit enzymes in regard to kinetic constants for the substrate benzyloxycarbonylphenylalanylarginine 7-(4-methyl)coumarylamide and rates of inactivation by the active-site-directed reagents benzyloxycarbonylphenylalanylphenylalanyldiazomethane and benzyloxycarbonylphenylalanylalanyldiazomethane. Thus clear characteristics of cathepsin L are now emerging, and these should simplify the identification of the enzyme in other tissues and species.

Cathepsin B↗
PubMed1985

Studies on the copper and zinc content of the rat kidney after treatment with cisplatin.

The administration of cis-dichlorodiammine platinum II (cisplatin), at a dose of 5 mg/kg, subcutaneously (s.c.), to adult male Wistar rats, inhibited the normal accumulation of Cu and Zn in the kidneys. Cisplatin also produced a small increase in the concentration of Cu in the brain but had no significant effect on total Cu and Zn concentrations in the heart, thymus, liver, intestine, spleen, testes and muscle. Treatment of rats with 2 mg Cu2+/kg, intraperitoneally (i.p.), increased the renal Cu content whilst cisplatin pretreatment inhibited the uptake of Cu by the kidneys. The administration of cisplatin to the Cd2+-pretreated rat decreased the content of metallothionein-bound Cu in parallel with a reduction in total renal Cu content, but had no significant effect on the total renal content of Cd and Zn. Pretreatment with cisplatin decreased the subsequent uptake of Cd by 42% in the whole kidney and by 23% in the metallothionein fraction, but failed to reduce the Cd2+-induced accumulation of Cu in the kidneys. The significance of these observations in relation to the possible mechanism of the cisplatin-induced change in the Cu and Zn content of the kidney is discussed.

Animals↗
PubMed1985

Phalangeal bone ash as an aid in diagnosing some nutritional causes of lameness in sheep.

Normal bone ash levels were determined on first phalangeal bones from lambs dying of acute causes and from abattoir specimens. First phalanges were chosen because they represent a whole bone thereby ensuring constant and natural proportion which would be difficult if sampling only a portion of a bone. No practical difference in percentage ash, expressed in terms of green bone weight, was found between fore or hind feet of young male or female sheep. Consequently a single regression equation can adequately express the relationship between bone ash and bone length for sheep up to about 9 months of age. Lambs suffering from hypocuprotic osteoporosis or osteodystrophy consistent with hypovitaminosis D have phalangeal bone ash values which tend to lie outside the lower range expected for normal sheep with first phalanges of similar length. Consequently bone ash can be a useful aid in the diagnosis of certain nutritional causes of lameness in sheep.

Animals↗
PubMed1985

Congenital bilateral renal hypoplasia in Large White pigs.

Bilateral renal hypoplasia and/or agenesis was detected in 6 of 26 pure-bred Large White piglets in 2 consecutive litters. The affected piglets were all dead at birth. The defect was characterised by a variable nephrogenic zone beneath the renal capsule and by a greatly reduced number of glomeruli which were hypertrophied. The piglets were born to the same sow but they were sired by different boars. Both boars and the sow were related through their pedigree. A genetic basis for the defect, probably involving a recessive gene defect inherited in a simple Mendelian manner, seems likely.

Animals↗
PubMed1984

The purification and properties of cathepsin L from rabbit liver.

Cathepsin L was purified from rabbit liver by a method involving whole-tissue homogenization, pH precipitation, ammonium sulphate fractionation and chromatography on CM-Sephadex C-50, phenyl-Sepharose and Sephadex G-75. Pure enzyme was obtained without the necessity of laborious subcellular fractionation techniques. The Mr of the enzyme was determined to be 29 000 by gel filtration, and affinity for concanavalin A-Sepharose indicated that it was a glycoprotein. A novel technique for detection of enzyme activity in agarose isoelectrofocusing gels showed that the enzyme existed in multiple isoenzymic forms with pI values ranging from 5.0 to 5.9. The enzyme catalysed the hydrolysis of azocasein, collagen and Z-Phe-Arg-NMec (where Z and NMec indicate benzyloxycarbonyl and N-methylcoumarin derivative respectively) optimally at pH 5.2, 3.3 and 6.0 respectively. In addition, cathepsin L was found to degrade benzoyl-Phe-Val-Arg-NMec and 3-carboxypropionyl-Ala-Phe-Lys-NMec. However, cathepsin B also cleaved all of these substrates. One major difference between these two enzymes was in their Michaelis constants for Z-Phe-Arg-NMec; cathepsin B had Km 75 microM whereas that of cathepsin L was 0.7 microM. Cathepsin L was inhibited by all of the usual chemical inhibitors of thiol proteinases as well as the more specific inhibitors Z-Phe-Phe-CHN2, Z-Phe-Ala-CHN2, compound E-64 and compound Ep-475. Active-site titration with compound E-64 showed that the purified sample contained 80% active protein, which had kcat. 20s-1 for the substrate Z-Phe-Arg-NMec. Antibodies were raised to active cathepsin L, and these did not cross-react with cathepsin B, thus demonstrating that these two enzymes are immunologically distinct.

Animals↗
PubMed1984

Production of a monospecific antiserum to cathepsin L: the histochemical location of enzyme in rabbit fibroblasts.

A polyclonal antibody against rabbit cathepsin L was raised in goats and shown to be specific for both active and inactive enzyme. Using this antibody we have examined the distribution of cathepsin L in primary rabbit skin fibroblasts by immunohistochemistry and found that all the enzyme is located within lysosomal granules. At confluence many cathepsin-L-containing lysosomes were seen in each cell. A new but nonspecific histochemical substrate for cathepsin L was tested and a similar distribution was obtained. Our results indicate that the immunohistochemical technique can be reliably employed for the specific location of cathepsin L in cells and tissues.

Animals↗
PubMed1984

Death in sheep following dosing with copper diethylamine oxyquinoline sulphonate as a commercial injectable copper preparation.

Death occurred in sheep following diethylamine oxyquinoline sulphonate (DOS) copper injections given at recommended dose rates. The copper content in unused portions of DOS copper packs was normal and free of bacterial contamination. Liver and blood copper levels in dead and sick sheep were not high. Sick sheep showed signs of hepatic encephalopathy and dead sheep were generally piled against fences and scrub. Deaths were associated with acute, severe, generalised, centrilobular, hepatocellular necrosis and live sheep had elevated circulating levels of liver enzymes consistent with liver damage. In recovered sheep there were no residual complications. It would appear that even at 0.5 mg/kg of DOS copper the safety threshold may sometimes be exceeded in some sheep.

Animals↗
PubMed1984

Hereditary neuraxial oedema in a Poll Hereford herd.

Cases of neuraxial oedema in a Poll Hereford herd were investigated and the pedigrees of affected calves determined. In all cases, and over no more than 3 generations, the pedigree led back to a common bull. Analysis of the herd breeding records supported an autosomal recessive mode of inheritance of the disease. Fractures of the femoral heads, acetabular cartilage and/ or bone, or both, were seen in some affected calves. This lesion was probably induced during birth or soon after, and the suggestion is made that such hip lesions could be regarded as highly suggestive of hereditary neuraxial oedmea of Herefords. The majority of calves showed clinical signs at birth, but 2 calves did not develop clinical signs until they were 2 days old.

Acetabulum↗
PubMed1984

A review of public health regulations on lead.

A review of public health regulations pertaining to lead exposure is the subject of this paper. Although lead had been used for centuries in the fabrication of a host of products, it was not until the mid-nineteenth century that the clinical pattern of lead poisoning was described in the medical literature. With this recognition gradually came government health regulations designed to limit human exposure to lead from occupational and environmental sources. The British, in particular, developed during the period 1890 to 1920 comprehensive rules and regulations pertaining to occupational lead exposures. The development and imposition of U.S. health regulations occurred later in the twentieth century; federal regulations not generally appearing until the 1970's. At present, several U.S. government agencies have promulgated regulations intended to prevent lead poisoning from paint; limit lead in ambient air, drinking water, workplace environments and consumer products; and reduce lead in fuels and fuel additives used in motor vehicles. These regulations are reviewed in terms of their extent of coverage. There is evidence, in some instances indirect in nature, that human exposure to lead in U.S. populations has been reduced, though comprehensive data are lacking. The Centers for Disease Control has reported that the mean blood lead level in the U.S. has decreased 36%, paralleling a reduction in the lead content of gasoline. For occupational lead exposure, comprehensive morbidity data do not exist, but an evaluation of NIOSH health hazard evaluations (HHE's) specific to lead show a gradual reduction since 1977 in the percentage of HHE's for which airborne lead exceeded 0.20 mg/m3, which at one time had been the federal standard for occupational lead exposure, prior to reduction of the U.S. standard to 0.05 mg/m3.

Adult↗