Sensing Coherent Dynamics of Electronic Spin Clusters in Solids.

We observe coherent spin exchange between identical electronic spins in the solid state, a key step towards full quantum control of electronic spin registers in room temperature solids. In a diamond substrate, a single nitrogen vacancy (NV) center coherently couples to two adjacent S=1/2 dark electron spins via the magnetic dipolar interaction. We quantify NV-electron and electron-electron couplings via detailed spectroscopy, with good agreement to a model of strongly interacting spins. The electron-electron coupling enables an observation of coherent flip-flop dynamics between electronic spins in the solid state, which occur conditionally on the state of the NV. Finally, as a demonstration of coherent control, we selectively couple and transfer polarization between the NV and the pair of electron spins. Our observations enable the realization of fast quantum gate operations and quantum state transfer in a scalable, room temperature, quantum processor.

Biochemical study of sialidosis type I in a Russian family.

A 7-year-old boy from a Russian family with decreased vision and a cherry-red spot but without any somatic and mental abnormalities is described in this paper. The decreased neuraminidase activity in the child's leukocytes and cultured skin fibroblasts and his 10-fold increase in urinary sialyloligosaccharides allowed us to conclude that he was affected by type I sialidosis. Some other results of the biochemical study of this child and his parents are presented. It is the first case of sialidosis in the Russian population.

Interaction of hepatic asialoglycoprotein receptor with asialoorosomucoid and galactolyzed lysosomal alpha-glucosidase.

An asialoglycoprotein receptor was isolated from murine liver and purified more than 1600-fold using 2-fold affinity chromatography on asialoorosomucoid-Sepharose. The purified receptor did not interact with 125I-orosomucoid, but bound to 125I-asialoorosomucoid. The binding of the receptor to asialoorosomucoid was saturable. The dissociation constant of the receptor-asialoorosomucoid complex was 0.4 X 10(-9) M. The molecular mass of the receptor, as determined with the use of specific antibodies by the immunoblotting method, was 43 kDa. High concentrations of unlabeled asialoorosomucoid and of n-aminophenyl-beta-D-galactosyl derivatives of bovine serum albumin, ovalbumin and acid alpha-glucosidase from human liver inhibited the binding of the receptor to 125I-asialoorosomucoid almost completely. The binding of the receptor to 125I-galactolyzed alpha-glucosidase was pH-dependent, with the pH optimum at 8.0-9.0. It was shown that, as in the case of 125I-asialoorosomucoid, the binding of the 125I-galactosyl derivative of alpha-glucosidase occurred in the presence of Ca2+ and was inhibited by N-acetylgalactosamine. Glycoproteins containing galactose as a terminal residue inhibited the interaction of the receptor with 125I-galactolyzed alpha-glucosidase. The possibility of directed transport of the galactolyzed alpha-glucosidase derivative into parenchymous liver cells using receptor-mediated endocytosis is discussed.

Prenatal exclusion of metachromatic leukodystrophy by estimation of arylsulphatase A activity in chorion and cultured amniotic fluid cells.

Chorion biopsy specimens were used for prenatal assay of arylsulphatase A activity in a pregnant woman whose two children had died from metachromatic leukodystrophy (MLD). As in two subsequent pregnancies chorion arylsulphatase A was in the control range, it was concluded that both fetuses were healthy. Absence of MLD in the fetus from the first pregnancy was confirmed after assay of arylsulphatase A activity in fetal organs. The second pregnancy resulted in delivery of a healthy child.

An unusual case of mannosidosis with severe deficiency of acid mannosidase in leukocytes and high residual enzymatic activity in skin fibroblasts.

A case of mannosidosis with high residual activity of fibroblast acid mannosidase is described. The mutant enzyme was thermostable and has an almost normal Km value. The patient had mild clinical manifestations, but excretion of mannose-rich oligosaccharides was very high. This case of mannosidosis is compared with those reported in literature.

Serum lipoproteins of patients with glycogen storage disease.

Seventeen patients with different types of glycogen storage disease (GSD) were under observation. The type of the disease was defined from glucaemic and lactotaemic curves obtained in glucose, galactose and adrenaline tolerance tests and by biochemical analysis of liver biopsy specimens. Seven patients were found to have Type I; five patients, Type III; one patient, Type VI; and four patients, the Type IX (or X) of GSD. The serum lipoprotein (LP) content was determined in all patients using analytical ultracentrifugation. Hyperlipoproteinaemia (HLP) was found in virtually all patients. Patients with Type I of GSD were found to have Types 2b and 4 of HLP; and patients with Type III of GSD, 2b Type of HLP. 2a Type of HLP was diagnosed in patients with GSD of VI and IX (X) Types. Patients with Type III GSD, in contrast to those with GSD of other types, had enhanced levels of Sf 12-20 LP. The levels of Sf 100-400 and Sf 20-100 LP were greatly increased only in patients with Type I GSD.

Carbohydrate content of acid alpha-glucosidase (gamma-amylase) from human liver.

The presence of carbohydrates in homogeneous preparations of human liver acid alpha-glucosidase has been established and the carbohydrate content of the enzyme determined. The enzyme was purified with the specific purpose of removing all low-molecular-weight carbohydrates. It was specifically adsorbed on Concanavalin A-Sepharose, eluted with methyl-alpha-D-mannopyranoside and gave a positive reaction with the phenol-sulphuric acid reagent. These facts taken together provide evidence that the enzyme studied is a glycoprotein. The analysis of the carbohydrate content of human liver acid alpha-glucosidase showed that there were 8.3 glucosamine, 13.2 mannose and possibly 3--4 glucose residues per molecule of the enzyme with a molecular weight of 98,000.

Studies on some biologically active dextrans.

The relationship between the structures of six native dextrans and their effects on nonspecific resistance to infection (n.s.r.i.) in mice and also anticomplementary activity has been studied. The data obtained showed that the n.s.r.i. activity of dextrans generally increased with increase of extent of branching, but no direct correlation between these two factors was found. Data on exodextranase-catalyzed hydrolysis of dextrans suggest that the length of the outer chains may be important for the n.s.r.i. activity of the dextrans. Dextrans characterized by a significant extent of branching were anticomplementary, but no relationship between extent of branching and anticomplementary activity was observed.

Two cases of unusual Type I glycogenosis.

Two patients with apparent clinical manifestations of glycogen storage disease were described. The curves obtained upon glucose and adrenalin tolerance tests were indicative of glycogen storage disease Type I. Liver biopsies showed the increased glycogen concentration; however, the activities of the enzymes involved in glycogen metabolism, including glucose-6-phosphatase activity, were within normal limits or even slightly enhanced. On the basis of the biochemical data, Type Ib glycogenosis was diagnosed. The analytical ultracentrifugation studies of serum lipoproteins of those patients showed that concentration of very low density lipoproteins was considerably increased.

[Alpha-L-fucosidase activity in human blood]. / Al'fa - L-Fukozidaznaia aktivnost' cheloveka.

The alpha-L-fucosidase activity was studied in blood plasma and cells. In leucocytes and blood plasma of healthy persons the fucosidase activity varied considerably. The fucosidase activity in blood was not altered under pathological conditions other than fucosidosis. The fucosidase activity did not depend on sex and age of the persons studied. No correlation was observed between the values of the fucosidase activity. Two forms of fucosidase (alpha-L-fucosidase I and alpha-L-fucosidase II) were found in human leucocytes and blood plasma. Isoelectric focusing experiments indicates multiple forms alpha-L-fucosidase from human serum. The possibility is discussed of the use of human blood plasma and cells not only for estimation of the total fucosidase activity but also for studies of different forms of the enzyme.