Supplemented creatine induces changes in human metabolism of thiocompounds and one- and two-carbon units.

The administration of creatine (5 g/day for one month) to 11 young active sportsmen affected their urinary excretion of creatine, creatinine, and thiodiglycolic acid (TDGA) as well as blood levels of homocysteine, vitamin B12 and folates. The probands were divided into four groups, according to the amount of creatine found in urine, and of folates and vitamin B12 determined in blood. The changes of folates and vitamin B12 were mutually reciprocal. Each group utilized CR as donor of one- and two-carbon (1C and 2C) units by means of homocysteine (HoCySH), folates, and vitamin B12, in different metabolic pathways. In 10 men the creatine administration was accompanied by an increase of HoCySH level in blood, while in the last man, with accidentally discovered hyperhomocysteinemia, the HoCySH level dropped by 50%. Differences between initial and terminal TDGA levels indicate that creatine affects equilibria of redox processes. Creatinine excretion into urine changed in the dependence on the extent of metabolic disturbances.

Diagnostic significance of urinary thiodiglycolic acid as a possible tool for studying the role of vitamins B12 and folates in the metabolism of thiolic substances.

We have found that the determination of thiodiglycolic acid (TDGA) in urine may help to characterize metabolic imbalance of substances participating in methionine synthesis, which leads to hyperhomocystinuria. From the metabolic scheme, based on a proper combination of known facts, we attempted to theoretically explain and to demonstrate the possibilities of TDGA formation via different ways of homocysteine transformation. This scheme was used in evaluating the results obtained by testing urine of a woman suffering from impaired function of methionine synthase reductase (CblE type of homocystinuria). The amount of TDGA excreted in her morning urine was very sensitive to the changes in her treatment based upon a combination of N5-formyl tetrahydrofolate, betaine and vitamin B12. Vitamin B12 given in the evening either alone or together with betaine increased the TDGA excretion in the morning urine up to ten times. On the other hand, in the absence of vitamin B12, betaine in combination with N5-formyl tetrahydrofolate hindered the appearance of TDGA in the morning urine. Generally, the determination of TDGA in urine of an appropriately pretreated patient may indicate the degree of success of the treatment.

CblE type of homocystinuria due to methionine synthase reductase deficiency: clinical and molecular studies and prenatal diagnosis in two families.

The cblE type of homocystinuria is a rare autosomal recessive disorder, which manifests with megaloblastic anaemia and developmental delay in early childhood. This disease is caused by a defect in reductive activation of methionine synthase (MTR). Our study was directed at clinical, biochemical, enzymatic and molecular characterization of two Czech patients with the cblE type of homocystinuria. Case 1 involves a 20-year-old mentally retarded patient who presented with megaloblastic anaemia at 10 weeks of age. She was treated with folates and vitamin B12, and subsequent attempts to cease administration of folates led to recurrence of megaloblastic anaemia. Biochemical features included severe hyperhomocysteinaemia and hypomethioninaemia and in fibroblasts defective formation of methionine from formate, and no complementation with cblE cells. Subsequent molecular analysis of the methionine synthase reductase (MTRR) gene revealed compound heterozygosity for a transition c.1459G>A (G487R) and a 2bp insertion (c.1623-1624insTA). Case 2 involves an 8-year-old girl with nystagmus and developmental delay in whom megaloblastic anaemia was detected at 11 weeks of age. Severe hyperhomocysteinaemia with normal methionine levels was found and enzymatic and complementation studies confirmed the cblE defect. This patient is homozygous for a 140 bp insertion (c.903-904ins140). The insertion is caused by a T>C transition within intron 6 of the MTRR gene, which presumably leads to activation of an exon splicing enhancer. In the families of both patients, enzymatic and mutation analyses were successfully used for prenatal diagnosis. Our study expands the knowledge of the phenotypic and genotypic variability of the cblE type of homocystinuria and supports the concept that this disorder is caused by mutations in the MTRR gene.

Trends in exploitation of packed red blood cells.

The following trends aim to a more efficient exploitation of packed red blood cells (PRBC): 1. Improvement of the operative distribution of PRBCs for transfusions before expiration. 2. Prolongation of the expiration time by monitoring the biochemical and physical processes during banking. Maintenance of native hemoglobin and restoration or substitution of substances involved in transport of energy and of oxygen are of utmost importance. Enzymic conversion of RBCs of blood group A, B to 0 is not supposed to leave laboratory scale soon. While cryo-conservation of RBCs with glycerine is known, freeze-drying of PRBCs remains a speculation. 3. Use of PRBCs after expiration as a raw material for products applicable in medicine and biochemistry. Stroma-free hemoglobin variants (SFH) are known as effective infusable oxygen carriers in experimental animal models. However, there is little convincing evidence on the metabolism and innocuity of SFH variants in human organism. Therefore, systemic infusion of SFH solutions is not yet acceptable to clinicians even in emergency situations. On the other hand, a broader use of SFH and its variants is anticipated and regarded as prospective in organ perfusion, cardioplegy and transplantation as well as in analytical biochemistry.

Organ distribution of fibrinogen-bound methotrexate in mice with Gardner lymphosarcoma.

The distribution of fibrinogen-bound 3H methotrexate was investigated in Gardner lymphosarcoma bearing mice. 3H labeled methotrexate (3H MTX) was covalently bound by means of aminopropyl carbodiimide to bovine and mouse fibrinogen (FBG). The preparations as well as the free 3H MTX were applied i.v. in a single dose to three groups of C3H mice on day 6 after the inoculation of Gardner lymphosarcoma. 3H MTX level was determined in the blood, spleen, tumor and liver. Sufficient amounts of MTX were released by proteolysis of FBG-MTX derivatives to induce chemotherapeutical effects. Protracted accumulation of MTX applied in the form of FBG-MTX derivatives was found in the spleen and in the liver, in contradistinction to free drug application, suggesting the proteolytic degradation as a directing step responsible for the prolonged persistence of FBG-MTX derivatives in the organs. In the tumor the highest amount of MTX was released from mouse FBG supporting the view of ready uptake of homologous FBG by tumors.

The effect of folate binding protein on the colony-forming activity of GM-CFC cells in vitro.

A modified method for the preparation of specific folate binding protein was described. The GM-CFC stimulating activity of this SFBP preparation was investigated on tissue cultures of human bone marrow cells. It has been found that in the presence of HPCM the cell proliferation was markedly increased by the SFBP. In the absence of HPCM, however, the cell proliferation has been influenced either positively or negatively presumably in dependence on the expression of folate receptors on the GM-CFC bone marrow cells.