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Biomedical subjects

R W Carrell

Publications and source records attributed to R W Carrell.

At least 127 records · Page 7Linked to original sources
PubMed1986

alpha 1-Antitrypsin Christchurch, 363 Glu----Lys: mutation at the P'5 position does not affect inhibitory activity.

alpha 1-Antitrypsin Christchurch was isolated from the plasma of a Cambodian woman who was heterozygous for this variant and for the normal M protein. Tryptic peptide maps revealed that the inhibitory-site peptide, 359-365 Ser-Ile-Pro-Pro-Glu,Val,Lys, was missing and replaced by two new peptides Ser-Ile-Pro-Pro,Lys and Val-Lys, indicating a mutation of 363 Glu----Lys. There was no obvious clinical condition associated with this new antitrypsin. Competition experiments showed that antitrypsin Christchurch reacted at the same rate as normal antitrypsin in the presence of limiting amounts of trypsin, chymotrypsin, thrombin and neutrophil elastase. Both inhibitors were inactivated by catalytic amounts of papain. This inactivation was due to cleavage at the phenylalanine residue at the P7 position, seven residues towards the N-terminal of the inhibitory site. A one-step ethanol extraction procedure is described for isolating the papain cleavage products.

Adult↗
PubMed1986

Alpha-1-antitrypsin-Pittsburgh. A potent inhibitor of human plasma factor XIa, kallikrein, and factor XIIf.

Alpha-1-antitrypsin-Pittsburgh is a human variant that resulted from a point mutation in the plasma protease inhibitor, alpha 1-antitrypsin (358 Met----Arg). This defect in the alpha 1-antitrypsin molecule causes it to have greatly diminished anti-elastase activity but markedly increased antithrombin activity. In this report, we demonstrate that this variant protein also has greatly increased inhibitory activity towards the arginine-specific enzymes of the contact system of plasma proteolysis (Factor XIa, kallikrein, and Factor XIIf), in contrast to normal alpha 1-antitrypsin, which has modest to no inhibitory activity towards these enzymes. We determined the second-order-inactivation rate constant (k'') of purified, human Factor XIa by purified alpha 1-antitrypsin-Pittsburgh and found it to be 5.1 X 10(5) M-1 s-1 (23 degrees C), which is a 7,700-fold increase over the k'' for Factor XIa by its major inhibitor, normal purified alpha 1-antitrypsin (i.e., 6.6 X 10(1) M-1 s-1). Human plasma kallikrein, which is poorly inhibited by alpha 1-antitrypsin (k'' = 4.2 M-1 s-1), exhibited a k'' for alpha 1-antitrypsin-Pittsburgh of 8.9 X 10(4) M-1 s-1 (a 21,000-fold increase), making it a more efficient inhibitor than either of the naturally occurring major inhibitors of kallikrein (C-1-inhibitor and alpha 2-macroglobulin). Factor XIIf, which is not inhibited by normal alpha 1-antitrypsin, displayed a k'' for alpha 1-antitrypsin-Pittsburgh of 2.5 X 10(4) M-1 s-1. This enhanced inhibitory activity is similar to the effect of alpha 1-antitrypsin-Pittsburgh that has been reported for thrombin. In addition to its potential as an anticoagulant, this recently cloned protein may prove to be clinically valuable in the management of septic shock, hereditary angioedema, or other syndromes involving activation of the surface-mediated plasma proteolytic system.

Factor IX↗
PubMed1986

Kinetic studies on the interaction of alpha 1-proteinase inhibitor (Pittsburgh) with trypsin-like serine proteinases.

The rates of interaction of a number of serine proteinases with a mutant form of alpha 1-proteinase inhibitor (referred to as alpha 1-proteinase inhibitor (Pittsburgh)), in which a methionine-358 to arginine-358 mutation has occurred, have been determined. An approximately 6,000-fold increase in the second order association rate constant with human thrombin was observed (48 M-1 X s-1 for the normal protein to 3.1 X 10(5) M-1 X s-1 for the arginine mutant), confirming previously observed data using bovine thrombin (Owen, M.C., Brennan, S.O., Lewis, J.H. & Carrell, R.W. (1983) New England J. Med. 309, 694-698). However, substantial increases in the rates of association with other trypsin-like enzymes were also noted, indicating that the replacement of methionine by a basic residue affects all serine proteinases with this kind of specificity. There was a marked decrease in the rates of interaction of the Pittsburgh mutant with both human neutrophil elastase and porcine pancreatic elastase, the inhibitor being converted into lower molecular mass fragments after interaction with either enzyme. Butanedione caused a substantial loss in the inhibitory activity of the arginine mutant, while having no effect on the normal protein. These data, when compared to those previously reported for differences in reaction rates between normal and oxidized alpha 1-proteinase inhibitor (Beatty, K., Bieth, J. & Travis, J. (1980) J. Biol. Chem. 255, 3931-3934), are consistent with the interpretation that the amino acid in the P1-position at the reactive site of this protein has a marked effect on determining its primary specificity.

Blood Proteins↗
PubMed1986

Two de novo mutations in one beta globin chain: hemoglobin Atlanta-Coventry, beta 75 Leu----Pro and beta 141 Leu deleted.

Reverse phase HPLC analysis of a hemolysate from a patient with hemolytic anemia revealed the presence of three different beta globins. Reverse phase Peptide mapping and amino acid analysis indicated that one was normal beta A (66%), one was beta Atlanta (beta 75 Leu----Pro, 23%) and the third, beta Atlanta-Coventry, contained two mutations beta 75 Leu----Pro and beta 141 Leu deleted. The parents and four siblings of the propositus had only beta A chains, while two of his children inherited the beta Atlanta and beta Atlanta-Coventry chains from him, and beta A Chains from their mother. His third child was normal, possessing only beta A chains.

Adult↗
PubMed1985

Human alpha 1-antitrypsin expression in Xenopus oocytes. Secretion of the normal (PiM) and abnormal (PiZ) forms.

Injection of equivalent amounts of normal (PiMM) or abnormal (PiZZ) alpha 1-antitrypsin mRNA into Xenopus oocytes resulted in secretion of both the normal and abnormal alpha 1-antitrypsin. A much lower proportion of the abnormal protein was secreted, and the Z alpha 1-antitrypsin that was not secreted accumulated within the cell in a high-mannose form. The time taken for secretion of the normal and abnormal proteins was identical. Both the secreted and intracellular alpha 1-antitrypsin synthesized by oocytes were functionally active.

Animals↗
PubMed1985

Alpha 1-antitrypsin and serum albumin mRNA accumulation in normal, acute phase and ZZ human liver.

Alpha 1-Antitrypsin and albumin mRNA levels of 4 human livers were assessed using a newly sequenced cDNA clone of the carboxyterminal third of alpha 1-antitrypsin and a previously cloned albumin cDNA sequence. The relative concentration of alpha 1-antitrypsin mRNA was the same in poly(A)-containing RNA isolated from acute phase (MM) and alpha1-antitrypsin deficient (ZZ) individuals. In the acute phase liver relative to the normal (MM) liver, total RNA extracts showed a marked decrease in albumin mRNA concentration but no increase in alpha 1-antitrypsin mRNA. The ZZ liver showed decreased total and poly(A)-containing RNA content but the same proportion of alpha 1-antitrypsin to albumin mRNA as in the normal (MM) liver. This supports other evidence that ZZ alpha 1-antitrypsin deficiency is due to a defect in polypeptide processing (secretion) rather than a deficiency in mRNA accumulation.

Adolescent↗
PubMed1985

Polycythaemia associated with a new haemoglobin variant: haemoglobin Palmerston North beta 23 (B5) val----phe.

A new haemoglobin variant, with increased oxygen affinity, has been identified in a patient with a long history of polycythaemia. This new haemoglobin, Hb Palmerston North, has an amino acid substitution of valine to phenylalanine at position beta 23 (B5). The increased oxygen affinity is accompanied by a decrease in globin stability which was responsible for the laboratory detection of the haemoglobinopathy.

Aged↗
PubMed1985

Human Z alpha 1-antitrypsin accumulates intracellularly and stimulates lysosomal activity when synthesised in the Xenopus oocyte.

Microinjection of human liver mRNA from a patient homozygous for alpha 1-antitrypsin deficiency (PiZZ) into Xenopus oocytes led to a 2--10-fold increase in lysosomal activity. Stimulation of lysosomal activity was not observed when mRNA from a normal human liver (alpha 1-antitrypsin PiMM), or water was injected into the oocyte. This lysosomal activity was oocyte derived and was not due to translation products of the human liver mRNA. Thus a protein that accumulates intracellularly in the secretory pathway is capable of stimulating lysosomal activity.

Animals↗
PubMed1985

Smoking, lung function, and alpha 1-antitrypsin deficiency.

From 1970 to 1983, 69 individuals (aged from infancy to 87 years) with homozygous alpha 1-antitrypsin deficiency (ZZ) were followed up. 12 had liver disease. Amongst the 33 patients with emphysema mean age of onset of dyspnoea in smokers (32 years) was significantly lower than that in non-smokers (51 years). Mean age at death (excluding that from liver disease) was 48 years in smokers and 67 in non-smokers. In non-smokers mean FEV1 was 77% of that predicted, but in smokers it was only 38% of that predicted. In non-smokers, FEV1 declined with age, but there was considerable individual variation. In smokers, the decline correlated with the extent of cigarette smoking in pack years. Mean decrease in FEV1 in non-smokers was abnormally high (80 ml/year), but significantly less than the massive mean decline of 317 ml/year in smokers. In ex-smokers the mean rate of decrease was 61 ml/year.

Adult↗
PubMed1984

A genetically engineered mutant of alpha 1-antitrypsin protects connective tissue from neutrophil damage and may be useful in lung disease.

The effectiveness of a genetically engineered mutant of human alpha 1-antitrypsin (358 Met----Val) as an inhibitor of connective tissue breakdown was tested in a model of inflammation. The degradation of basement membrane collagen by stimulated neutrophils was efficiently inhibited by a tenfold lower concentration (0.2 mg/ml) of the mutant inhibitor than of the normal alpha 1-antitrypsin (2.4 mg/ml). Effective inhibition by normal alpha 1-antitrypsin occurred at much lower concentrations when azide or catalase was added, or when normal neutrophils were replaced by those from a donor with chronic granulomatous disease. These results confirm that neutrophils augment tissue proteolysis by the oxidative inactivation of the methionine at the reactive centre of alpha 1-antitrypsin. The replacement of this methionine by valine gives an effective inhibitor that is not inactivated by neutrophil oxidants. The availability of this genetically engineered mutant suggests the possibility of prophylaxis of lung dysplasias, notably emphysema, and of the shock syndromes associated with massive neutrophil activation.

Basement Membrane↗
PubMed1984

Structural and functional characterization of the abnormal Z alpha 1-antitrypsin isolated from human liver.

alpha 1-Antitrypsin has been isolated from liver inclusion bodies of a subject with a homozygous Z deficiency. The inhibitor was recovered in a fully active form by extraction in high salt at either pH 2.0 or pH 8.0. Carbohydrate analysis indicated a protein in the 'high mannose' form, and this was collaborated by its sensitivity to endo-beta N-glucosaminidase. These data suggest that the abnormal alpha 1-antitrypsin is blocked in the secretory pathway prior to its entrance into the Golgi, and that this blockage is not due to a gross misfolding of the polypeptide.

Carbohydrates↗
PubMed1984

Circulating proalbumin associated with a variant proteinase inhibitor.

The unique finding of normal proalbumin in human plasma provides an insight into the mechanism of propeptide cleavage. Proalbumin, present as 1-5% of the total albumin, was found in a boy whose prime problem was the presence of a mutant proteinase inhibitor, alpha 1-antitrypsin Pittsburgh (358 Met----Arg) [2]. The inferred structure of human proalbumin was confirmed as Arg-Gly-Val-Phe-Arg-Arg-Alb. On incubation with various enzymes (trypsin, tryptase, thrombin, chymotrypsin, chymase and cathepsin B), only trypsin was capable of converting proalbumin to albumin. There was no conversion when proalbumin was incubated with whole blood, plasma or serum. However, intravenous injection of proalbumin into a rat resulted in complete conversion to albumin, the half-life of this process being 6 h. We conclude that propeptide cleavage is dependent on a serine proteinase which is inhibited intracellularly, by the mutant inhibitor, and that all the albumin in the boy was secreted as proalbumin, but was subjected to a separate cleavage process after export from the hepatocyte.

Adolescent↗
PubMed1984

Oxidative interactions between haemoglobin and membrane lipid. A liposome model.

The relationship between haemoglobin and membrane oxidation was studied using liposomes containing haemoglobin (haemosomes) as a red cell model. Rapid oxidation occurred in haemosomes formed from purified haemoglobin and unsaturated lipid (egg phosphatidylcholines). After 3 h at 37 degrees C most of the haemoglobin was oxidized, predominantly to methaemoglobin with some haemichrome formation. The oxidation of haemoglobin was paralleled by membrane lipid peroxidation as measured by thiobarbituric acid reactivity. These changes were largely abolished by using freshly prepared haemolysate instead of purified haemoglobin, or when haemosomes were prepared with saturated phosphatidylcholines. In haemosomes consisting of fresh haemolysate and saturated phosphatidylcholine, the rate of haemoglobin oxidation at 37 degrees C corresponded to that of non-encapsulated haemolysate, and after 4 months storage at 4 degrees C 45% of oxyhaemoglobin was oxidized. In haemosomes prepared from purified haemoglobin and egg lecithin, alpha-tocopherol, catalase and ascorbate each protected against both haemoglobin oxidation and lipid peroxidation. Superoxide dismutase or reduced glutathione had no effect. In unsaturated-lipid haemosomes containing haemolysate, the rate of haemoglobin oxidation increased when catalase was inhibited or reduced glutathione was depleted, but after long term incubation only concurrent catalase-inhibition and glutathione depletion could increase thiobarbituric acid reactivity. These results demonstrate a close interdependence between haemoglobin oxidation and lipid peroxidation, and show that constituents of haemolysate strongly protect against both processes. H2O2 appears to be an important mediator, with its removal by either catalase or the glutathione/glutathione peroxidase system protecting against both oxidative changes.

Catalase↗