Hexokinase from rabbit red blood cells.
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Animals↗
Biomedical subjects
M Magnani
Publications and source records attributed to M Magnani.
Human erythrocyte galactokinase: a population survey.
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Adolescent↗
A new variant of galactokinase.
A new variant of human galactokinase activity is described. This enzyme shows reduced catalytic activity both in red and white blood cells, lower Km for ATPMg2-, and increased in vivo instability when compared to the normal enzyme. Thermostability and pH optimum are not modified. We have labelled this enzyme the Urbino variant and have suggested the procedure to distinguish it from the allelic form (GALKG) responsible for galactosemia in the homozygous state.
Alleles↗
Enhanced biofunctionality of plastipore ossicular prostheses with the use of homologous cartilage.
Functional results with Plastipore prostheses inserted in 150 staged intact canal wall tympanoplasties at our Clinic are reported. Two groups of patients have been reviewed: The first group consists of those cases in which the prosthesis is directly in contact with the tympanic graft (77 cases); the second one comprises all cases with interposition of homologous cartilage between the head of the prosthesis and the tympanic graft (73 cases). The aim of this article is to see whether extrusion rate and audiometric and impedance result differences exist between the two groups. We have found a 15.4 percent extrusion rate in the group without cartilage but only a 1.9 percent rate in the group with cartilage (9.3 percent is the overall extrusion rate). There were no substantial differences in functional results between the two groups. It is valuable to outline the different functional results between the two types of prosthesis: TORPs got 56.8 percent excellent results and 78.4 percent good results, while PORPs had only 47.7 percent excellent results and 60 percent good results. Normal compliance (static compliance greater than 0.3 cc) was found in 61.6 percent of cases without cartilage and in 46.7 percent of cases with cartilage.
Biocompatible Materials↗
Rabbit red blood cell hexokinase. Evidence for two distinct forms, and their purification and characterization from reticulocytes.
Rabbit hexokinase (EC 2.7.1.1) has been shown to exist in the soluble fraction of reticulocytes as two distinct molecular forms, designated hexokinase Ia and hexokinase Ib, which are separable by ion exchange chromatography and polyacrylamide gel electrophoresis. Hexokinase Ia was found to be similar to the brain enzyme, while hexokinase Ib differs from every other previously reported hexokinase isozyme. Reticulocyte hexokinase Ia and Ib have been purified 55,000-and 50,000-fold, respectively, by a combination of ion exchange chromatography, affinity chromatography, and preparative polyacrylamide gel electrophoresis, as proteins homogeneous by sodium dodecyl sulfate-gel electrophoresis. The native proteins have the same molecular weight of 105,000 by gel filtration and sedimentation velocity on sucrose density gradients. Sodium dodecyl sulfate-polyacrylamide gels have a molecular weight of 104,000, indicating that the two forms are monomers. Hexokinase Ia had a pI of 6.2 to 6.3 pH units while hexokinase Ib had a pI of 5.7 to 5.8 pH units by isoelectric focusing. The two enzymes were specific for Mg.ATP and Mg.ITP as the nucleotide substrates. Several hexoses could be phosphorylated by hexokinase Ia and Ib with different affinities.
Animals↗
The possibility of prenatal diagnosis by gene dosage: confirmation of duplication 10q24 to qter from GOT-1 activity in fetal erythrocytes.
The activity of four enzymes, including GOT-1, has been investigated in he erythrocytes of a 10q to 24 qter trisomic fetus. Analyses have been performed on a feto-maternal blood mixture sampled by fetoscopy and on red cells obtained by cardiac puncture, following therapeutic abortion. The demonstration of a 40 per cent increase of GOT-1 activity, as compared to normal fetuses of similar gestational age, suggests that gene dosage studies may be a useful confirmatory technique in prenatal diagnosis of unbalanced chromosomal aberrations. Practical application of a similar diagnostic approach is conditioned by (1) precise characterization of fetal chromosome imbalance; (2) confirmed assignment of the gene locus coding for the gene product under investigation; (3) evidence of a linear proportionality between gene dose and concentration of the gene product in patients with the same chromosome imbalance detected in the fetus; (4) knowledge of the range of normal variation at different weeks of gestation of the enzyme activity to be tested in the fetus; (5) safety of fetal sampling procedure.
Adult↗
Taurine and thermoregulation: behavioral and cellular studies.
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Animals↗
Expression of GALT in two unrelated 9p- patients. Evidence for assignment of the GALT locus to the 9p21 band.
The quantitative expression of GALT and galactose utilization have been investigated in two patients with 9p deletion. Case 1 had a distal deletion of the band 9p22 leads to pter, while case 2 had an interstitial deletion of the region 9p133 leads to p23. In the former patient GALT activity and galactose utilization were found to be normal: in the latter decreased GALT activity and a significant decrease of galactose utilization were present. The above findings suggest that the GALT locus is in the 9p21 band.
Chromosome Deletion↗
Hypothermia induced in rabbits by intracerebroventricular taurine: specificity and relationships with central serotonin (5-HT) systems.
The intracerebroventricular (i.c.v.) injection of taurine produced a fall in core temperature, the extent of which was dependent on the thermal gradient between the body and the environment. Concurrently, a sudden rise in ear skin temperature, which was maximal in the cold and negligible at 30 degrees C, was observed. The fever induced by i.v. injection of Escherichia coli endotoxin was antagonized by taurine. High temperatures produced by i.c.v. injection of prostaglandin E1 were also suppressed by taurine. Intracerebroventricular injections of bicuculline and strychnine, but not those of picrotoxin or pentylentetrazol, were able to reduce hypothermia induced by taurine. Intracerebroventricular injection of the taurine reuptake inhibitor guanidinoethyl sulfonate, on the contrary, did enhance the hypothermic response to taurine. Injection (i.c.v.) of serotonin (5-HT) elicited a fall in core temperature which was not accompanied by a rise in ear skin temperature, but was antagonized by the concurrent injection of the 5-HT antagonist methysergide. Pretreating animals with p-chlorophenyl-alanine caused a significant fall of brain 5-HT contents and a reduction of the hypothermic response to taurine. The latter effect was also observed when the animals were i.c.v. pretreated either the methysergide or with the 5-HT reuptake blockers chlorimipramine and Lilly 110140. These findings give support to the hypothesis that taurine-induced hypothermia in rabbits mediated by some taurine sensitive cells and, at least in part, by serotonergic synaptic mechanisms.
Animals↗
Ossicular chain reconstruction with plastipore prostheses.
Proper reconstruction of the ossicular chain is a fundamental prerequisite for good hearing results in staged tympanoplasties. The history of modern middle ear surgery shows that various synthetic materials have been proposed in past years for sound conducting mechanism reconstruction but all gave discouraging results and were soon abandoned. Plastipore is a new plastic material that seems to be well tolerated in the middle ear, and it is commercially available as pre-formed prostheses. We are reporting our experience with 140 cases operated on in our clinic (92 TORPs and 48 PORPs). Two groups of patients are reviewed: the first group consists of the cases in which the prosthesis is in direct contact with the tympanic graft; the second one includes the cases with interposition of cartilage between the head of the prosthesis and the tympanic graft. The purpose is to see whether extrusion rate differences exist in the two groups. Functional results (evaluated after at least six months show an air-bone gap of less than 15 dB in 57 percent of cases and an air-bone gap of less than 25 dB in 82 percent of cases. Five extrusions are reported (3.57 percent). We believe that staged tympanoplasties and tympanic reconstruction with molded heterograft can explain the excellent hearing results and the low extrusion rate of the prosthesis.
Cochlear Implants↗
Evidence of gene dosage effect for HK 1 in the red cells of a patient with trisomy 10pter leads to p13.
Quantitative evaluation of six red cell enzymes in a patient with trisomy 10p syndrome showed significantly increased activity levels of HK 1. These results are in agreement with the evidence derived from another similar patient and strongly support the idea of gene dosage effect of HK1 in the erythrocytes of 10p trisomics. It is suggested that the HK 1 structural locus may be in the 10 pter leads to p13 region.
Abnormalities, Multiple↗
[Preliminary results on the possible role of intestinal peroxidase (EC 1.11.1.7) in the biosynthesis of prostaglandins].
The ability of a partially purified rat ileum peroxidase to synthetize PGE2 and PGF2 alpha from arachidonic acid was researched. The enzyme preparation, when incubated anaerobically with H2O2 and arachidonic acid, produced a compound extractable with ethyl acetate which showed on TLC the same Rf as authentic PGE2. This compound, after elution from the gel, was able to contract the rat strip fundus preparation.
Animals↗
Hexokinase isozymic pattern during red cell aging.
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Animals↗
Action of oxidized and reduced glutathione on rabbit red blood cell hexokinase.
Reduced glutathione at 1 mM concentration is able to mantain rabbit red blood cell hexokinase (EC 2.7.1.1) in the reduced state with fully catalytic activity. At higher concentrations a marked inhibition is observed. In contrast, oxidized glutathione is a strong inhibitor of reduced erythrocyte hexokinase at all the concentration studied. Inactivation experiments show that some sulfhydryl groups reacting with oxidized glutathione are responsible for the enzyme inactivations. These findings suggest a cellular inter-relationship between redox and energetic metabolism coupled through glutathione at the hexokinase level.
Adenosine Triphosphate↗
Rabbit red blood cell hexokinase. Purification and properties.
Rabbit red blood cell hexokinase (EC 2.7.1.1.) has been purified 300,000-fold by a combination of ion exchange chromatography, affinity chromatography, and preparative polyacrylamide gel electrophoresis. The hexokinase activity has been isolated in 35% yield as a protein that is homogeneous by polyacrylamide and sodium dodecyl sulfate gel electrophoresis. The highest specific activity obtained was 145 units/mg of proteins. The native protein has a molecular weight of 110,000 by gel filtration on Ultrogel AcA 44 and 112,000 by sedimentation velocity on sucrose density gradients. Sodium dodecyl sulfate-polyacrylamide gels gave a molecular weight of 110,000 indicating that hexokinase is a monomer. The enzyme had a pI of 6.20 to 6.30 pH units by isoelectric focusing. The enzyme was specific for Mg . ATP and Mg . ITP as the nucleotide substrates. Several hexokinase with different affinities.
Adenosine Triphosphate↗
Evidence for the assignment of GUK 1 gene locus to 1q32 leads to q43 segment from gene dosage effect.
A male infant with dup (1) (q32 leads to q43) constitution is reported. He had mental and physical retardation and a constellation of dysmorphisms, which are considered characteristic of trisomics for the distal one-third of the long arm of chromosome 1. The assay for guanylate kinase 1 (GUK 1) activity showed a gene dosage effect and confirmed the regional assignment of this marker in the chromosomal region indicated by data derived from somatic hybrids.
Abnormalities, Multiple↗
Identification of the origin of a 22p+ chromosome by triplex dosage effect of LDH B, GAPHD, TPI and ENO2.
A 33p+ chromosome in the lymphocytes of an infant with mental deficiency and congenital malformations was found to be a de novo translocation that could not be characterized by banding methods. The demonstration of a dosage effect for four enzymes--TPI, GAPHD, LDHB, and ENO2--in the infant's erythrocytes was consistent with trisomy 12p. The observation demonstrates the usefulness of information provided by the human gene map in the characterization of small chromosome imbalances which defy accurate identification by available banding techniques.
Carbohydrate Epimerases↗
Erythrocytes of different ages: a new method of "in vivo" preparation.
This paper describes a new method for obtaining "in vivo" populations of homogeneous erythrocytes of a specific age. This method, proposed for experimental animals, is based on the induction of a large reticulocytosis (about 80%) by the administration of phenylhydrazine and the subsequent synchronized ageing of young red cells present, which is obtained by blocking the erythropoiesis with daily injections of Actinomycin D. The advantage of such a method over those published so far is that it produces substantial quantities of red blood cells of a specific age. A disadvantage however is that it is only possible to obtain cells of up to 30 days old.
Animals↗