F-19 MR imaging of glucose metabolism in the rabbit

Noninvasive metabolic magnetic resonance (MR) imaging reflecting glucose metabolism in the aldose-reductase-sorbitol (ARS) pathway was performed in the rabbit head; after administration of the fluorinated glucose analogue 3-fluoro-3-deoxy-D-glucose (3FD-glucose), fluorine-19 images were generated. Images of 3FD-glucose showed significant 3FD-glucose uptake by adipose tissue, indicating its buffering effects in case of excess loads of glucose. Images of 3-fluoro-3-deoxy-D-sorbitol (3FD-sorbitol) demonstrated the spatial distribution of aldose reductase activities and significant sorbitol accumulation in the lens. Images of 3-fluoro-3-deoxy-D-fructose (3FD-fructose) showed preferential uptake of fructose by muscle tissue. The extremely low toxicity of 3FD-glucose indicates promise for its clinical application in metabolic imaging.     

Early effects of cis-dichlorodiammine platinum (II) on tumor progression and programmed death of Ehrlich ascites carcinoma cells

We studied the effects of cis-dichlorodiammine platinum (II) on different pathways of cell death in cultured Ehrlich ascites carcinoma in vitro and on subsequent growth of transplanted tumor in vivo. One-hour incubation with the cytostatic modulated apoptosis in cell culture. However, exposure of cell culture to a minimal effective concentration of cis-platinum(II)diammine dichloride promoted the growth of transplanted tumor.     

Adherence of Mycoplasma pneumoniae to glass surfaces.

Attachment of M. pneumoniae to glass was quantitated in an experimental system enabling the settling down of [3H]palmitic acid-labeled cells onto glass cover slips. Attachment of mycoplasmas suspended in buffer increased with temperature, decreased with higher ionic strength, and showed a maximum at about pH 5.5. The findings suggest a participation of ionic bonds in the attachment process. Trypsin did not detach glass-bound mycoplasmas, and treatment of the cells with glutaraldehyde did not reduce their attachment to glass, suggesting that membrane components other than proteins may be involved in the attachment. Low concentrations (up to 20 mg/ml) of bovine serum albumin buffer. However, during the next few hours, attachment increased far above the bovine serum albumin control. This marked increase was reduced by more than half in the presence of chloramphenicol. Increased attachment was also observed when glucose (0.1 to 2 mg/ml) was added to the bovine serum albumin-containing buffer. The findings suggest different mechanisms for the attachment in protein-free buffer and in growth medium or glucose-containing bovine serum albumin buffer, respectively. The latter apparently requires metabolic activity of the mycoplasmas.     

Regulation of thrombin-induced mast cell degranulation by zinc and manganese

This study was undertaken to determine whether zinc, manganese and copper could regulate the thrombin-induced secretion of the granule-associated mediator, beta-hexosaminidase, from mast cells derived from mouse bone marrow. Exposure of thrombin to copper (2-100 microM) does not affect the enzyme-induced release of beta-hexosaminidase from the mast cells. Zinc at 50 microM reduced the degranulation of calcium ionophore A23187 activated cells by 75% and that of immunological challenge or thrombin by 30% each. Exposure of the thrombin to incremental concentrations of manganese (2-100 microM) prevents its degranulation activity in a dose-related fashion. 75% inhibition of the enzyme activity was achieved at 100 microM manganese. However, exposure of IgE sensitized or unsensitized cells to incremental concentrations of manganese (2-400 microM) prior to antigen or calcium ionophore A23187 stimulation, does not significantly affect the exocytosis of beta-hexosaminidase. The binding of purified human FITC-thrombin to E-mast cells was analyzed by fluorescence flow cytometry. All cells bound specifically the labelled thrombin. Pretreatment of the FITC-thrombin with 100 micron zinc or manganese had no effect on the binding of the labelled thrombin to the cells. It was assumed that manganese modulates either directly the thrombin activity or the substrate for the enzyme on the cell surface.     

DNA methylation pattern is determined by the intracellular level of the methylase.

Extrachromosomal plasmid DNA is transiently undermethylated in Escherichia coli during amplification in the presence of chloramphenicol. In addition, undermethylation of phage lambda DNA was observed after thermal induction of a lambda c1857 lysogen while the integrated lambda phage DNA was found to be fully methylated. These methylation pattern changes occur under conditions (extensive replication) in which the intracellular methylase level becomes limiting. In an E. coli strain that harbors a plasmid that carries the dam methylase gene and therefore overproduces dam methylase, there is no undermethylation of dam sites in either of the extrachromosomal DNAs. The sites that are methylated by the mec methylase in both plasmid and lambda phage DNAs were undermethylated in the dam overproducer as well. These results indicate that the intracellular level of the E. coli methylase determines the DNA methylation pattern.     

Pattern of methylation of two genes coding for housekeeping functions.

The distribution of sites that can be methylated was analyzed in the Chinese hamster adenine phosphoribosyl-transferase (aprt) gene and the patterns of methylation of this gene and the mouse dihydrofolate reductase (dhfr) gene were studied by using CpG restriction enzymes. Both genes were found to be unmethylated completely at their 5'-end region and methylated heavily throughout the rest of the gene. Because the hamster aprt gene can be inhibited by DNA methylation in vivo, the results suggest that 5' undermethylation of this gene may be a necessary condition for its expression. The pattern of methylation of each of these two genes was similar in sperm and all other somatic tissue DNAs. This is in contrast to many tissue-specific genes that were found to be highly methylated in sperm DNA and undermethylated in the tissue in which they are expressed. This result is consistent with the fact that both aprt and dhfr are key enzymes in the biosynthesis of nucleotides and therefore expected to be synthesized in all cells.     

Correction of ventricular late potentials with drug and non-drug methods in patients with essential hypertension

The aim of the work was to evaluate the effects of drug and non-drug methods of treatment of patients with essential hypertension (EH) on ventricular late potentials (VLP). One hundred and thirteen patients with I to II stage EH aged 30 to 73 (mean age 53 +/- 9.7 years) were included in the study. VLP were registered by recording signal-averaged ECG (SA-ECG) before and after treatment with antihypertensive preparations (lisinopril, nifedipine) and intravenous ozone therapy. VLP were detected in 34 (30%) of the EH patients. The study found a decrease in the frequency of VLP detection from 40% (8 patients) to 10% (2 patients) after therapy with the ACE inhibitor lisinopril. In the group of patients who received monotherapy with the calcium antagonist nifedipine the number of subjects with VLP before and after the treatment was the same, 3 patients or 20%. In the group receiving bi-component therapy with lisinopril, an ACE inhibitor, and nifedipine, a calcium antagonist, the number of patients with VLP fell from 4 subjects (28.6%) to 1 subject. These data were confirmed with significant SA-ECG parameters. The study also revealed that ozone therapy as a part of complex treatment of EH improved SA-ECG parameters, which manifested by a decrease in VLP from 29.7% to 14.1%.     

Selective growth of a population of human basophil cells in vitro.

An initially homogeneous population of basophilic polymorphonuclear leukocytes was derived from human fetal liver cells grown in culture for 5-7 days. The cells were characterized as basophils by their morphology, histologic staining characteristics, and histamine content, and by the presence of IgE receptors on their surface. In this culture system the basophils were viable for up to 10 days.