Determination of methylated amino acids in human serum by high-performance liquid chromatography

Employing high-performance liquid chromatography with isocratic elution using a two-column system (mu Bondapak C18 and mu Bondapak CN) and phenyl isothiocyanate as a fluorogenic reagent, NG-monomethylarginine (MMA). NG-dimethylarginines, and epsilon-N-trimethyllysine (TML) can be quatitatively separated from human serum samples. The recoveries of these amino acids were over 90%. It was observed that the serum concentrations of MMA, DMA and TML were significantly elevated in sera obtained from patients suffering from diabetes mellitus, hepatitis or hyperthyroidism, particularly the last condition.

Interrelationship between nuclear histone binding and cell proliferation

1. Binding of non-enzymatically [methyl-14C]-labeled histone H3 to nuclei isolated from young and old rat livers, regenerating rat liver, and tumor cells has been investigated. 2. Scatchard plot analysis indicated that various cell types had different binding capacity and different dissociation constant (Kd). 3. Nuclei isolated from younger rats had fewer binding sites and lower Kd (or higher Ka) values for [methyl-14C]H3 than those from older rats. 4. Fewer binding sites and lower Kd values were also observed with nuclei isolated from the maximally regenerating liver (24 hr after partial hepatectomy) and the fast-growing ascites tumor and Novikoff hepatomas. 5. These results strongly suggest that the number of binding sites and affinity of histone H3 for nuclei appears to be correlated with the degree of cell proliferation. 6. Fractionation of the [methyl-14C]H3 bound nuclei into nuclear membrane and nucleoplasm demonstrates that approx. 94% of radioactivity is associated with the former in which less than 6% of DNA is found, whereas 94% of total DNA is found in nucleoplasm. 7. This suggests that the binding of [methyl-14C]H3 to nuclei is independent of DNA present in each fraction.

Enzymatic methylation of in vitro synthesized apocytochrome c enhances its transport into mitochondria

The gene for iso-1-cytochrome c from Saccharomyces cerevisiae was recloned into a pSP65 vector containing an active bacteriophage SP promoter. The iso-1-cytochrome c gene was cloned as an 856-base pair XhoI-HindIII fragment. When the resulting plasmid was digested at the HindIII site 279 bases downstream from the termination codon of the gene and transcribed in vitro using SP6 RNA polymerase, full length transcripts were produced. The SP6 iso-1-cytochrome c mRNA was translated using a rabbit reticulocyte lysate system, and the protein products were analyzed on sodium dodecyl sulfate-polyacrylamide gels. One major band with a molecular weight of 12,000 was detected by autofluorography and coincided with the Coomassie staining band of apocytochrome c from S. cerevisiae. The product was also shown to be identical with that of standard yeast apocytochrome c on an isoelectrofocusing gel. The in vitro synthesized iso-1-apocytochrome c was enzymatically methylated by adding partially purified S-adenosyl-L-methionine:cytochrome c-lysine N-methyltransferase (protein methylase III, EC 2.1.1.59) from S. cerevisiae along with S-adenosyl-L-methionine to the in vitro translation mixtures. The methylation was shown to be inhibited by the addition of the methylase inhibitor S-adenosyl-L-homocysteine or the protein synthesis inhibitor puromycin. The principal type of methylated amino acid in the protein was found to be epsilon-N-trimethyllysine which accounted for 77% of the total. Finally, the methylation of in vitro synthesized iso-1-apocytochrome c was found to increase its import into mitochondria isolated from S. cerevisiae 2-4-fold over unmethylated protein, but not into rat liver mitochondria. This suggests that methylation facilitates the import of apocytochrome c into mitochondria by a specific receptor mechanism.

A three-dimensional Fourier descriptor for human body representation/reconstruction from serial cross sections

This paper presents a three-dimensional Fourier descriptor (FD3) for shape representation/reconstruction. The FD3 is a double Fourier transform of serial cross-sectional contours of a shape in three dimensions (3D), which retains all shape information and gives a compact and invariant representation. The inverse Fourier transform of the FD3 reconstructs the original 3D shape; and it also estimates volume in the process. The upper bound of error introduced by the 3D reconstruction from the FD3 is derived in the sense of supremum norm. The FD3 method is compatible with medical imaging technologies such as computed tomography (CT) or magnetic resonance imaging (MRI). As an illustration of the FD3 methodology, a human head shape is reconstructed from its MR images.

Synthesis of NG-monomethylagmatine, a decarboxylation product of NG-monomethyl-L-arginine

NG-Monomethylagmatine, a decarboxylation product of NG-monomethyl-L-arginine, has been synthesized by reacting putrescine with N,S-dimethylthiopseudouronium iodide. The structural identity of the product was confirmed by proton NMR and mass spectroscopy, and its properties were determined on thin-layer and electrophoretic chromatography.

Deficiency of AMP deaminase in erythrocytes

Six individuals with complete deficiency of erythrocyte AMP deaminase have been discovered. They are all healthy and have no hematological disorders. The deficiency is only in isozyme E, which is the erythrocyte type isozyme, and is inherited as an autosomal recessive trait. The frequency of the mutant gene is surprisingly high, one heterozygote in about 30 of the population in Japan, Seoul, and Taipei. The ATP level is approximately 50% higher in AMP-deficient erythrocytes compared to that of control cells. Degradation of adenine nucleotide is slower in the deficient erythrocytes than in the control erythrocytes.

Histone binding to isolated rat liver nuclei

Calf thymus histone H3 bound irreversibly to the isolated rat liver nuclei. The rate and extent of binding was a function of the incubation period and the concentration of both H3 and nuclei, but independent of the temperature. The binding was saturable and was inhibited by simultaneous presence of various histones. Approximately 94% of the bound H3 was associated with nuclear membrane fraction.

Inhibition of uridine phosphorylase from Escherichia coli by benzylacyclouridines

The benzylacyclouridines, potent and specific inhibitors of mammalian uridine phosphorylase, were also found to be inhibitors of uridine phosphorylase but not thymidine phosphorylase from Escherichia coli. Competitive inhibition was observed in all cases and the most potent of these compounds was HM-BBAU (5-(3-benzyloxybenzyl)-1-[(2'-hydroxy-1'-hydroxymethyl)methyl]urac il) with a Ki value of 0.15 microM. The inhibitory potencies of these compounds parallel those obtained with enzymes from mammalian sources [Niedzwicki et al., Biochem. Pharmac. 31, 1857 (1982) and Naguib et al., manuscript in preparation] indicating that the structure of the active site of uridine phosphorylase from E. coli may resemble that of the mammalian enzyme.

High 24-hour urinary C-peptide excretion in non-insulin dependent diabetes mellitus

The 24-hour urinary C-peptide excretion (UCPR) is a useful means of estimating total daily insulin secretion. To evaluate the daily insulin secretion rate in non-insulin dependent diabetes mellitus (NIDDM), we measured UCPR in 22 patients with NIDDM and 18 normal subjects. The mean (±SD) UCPR in the patients with NIDDM was 115.4±40.2 ug/day and that in normal subjects was 56.7±22.0 ug/day respectively with significantly higher values in the patients with NIDDM (P<0.0001). UCPR was positively correlated with body fat mass determined by measurement of skin fold thickness in both groups [r=0.51 in patients with NIDDM (n=22; p<0.02) and r=0.55 in normal subjects (n=18; p<0.02)], and was higher in NIDDM patients, even with the same degree of fat mass. There was no significant correlation between UCPR and body muscle mass both in the patients with NIDDM and normal subjects [r=0.16 in patients with NIDDM (n=22; p>0.1) and r=0.16 in normal subjects (n=18; p>0.1)]. This result suggested that the total daily insulin secretion rate in NIDDM be increased to compensate insulin resistance, especially that induced by adipose tissues.

Epidemiologic study of hepatitis B in pregnant Korean women

The positive rates of hepatitis B viral markers according to many epidemiologic factors were analyzed in 2,873 pregnant women who delivered at St. Columban’s Hospital in Mokpo City from April 1st, 1985 to March 31st, 1986.

The following results were obtained: The overall HBsAg positivity in all pregnant women was 8.3%. The positive rate of HBsAg was unrelated to age. It was 13.2% in the 11–20 year age group. 12.5% in the 31–40 year age group, 7.8% in the 21–30 year age group and 0.0% in the 41–50 year age group. The positive rate of HBsAg was slightly related to locality. It was a little higher in women who grew up in rural areas (8.6%) than in urban areas (7.7%). The positive rate of HBsAg was unrelated to educational background. The positive rate of HBsAg was unrelated to economic status. It was 8.7% in the highest income group and 8.6% in the lowest income group. The positive rate of HBsAg was higher in cases who had injections more than four times. The positive rate of HBsAg was higher, but not significantly, in cases who had received blood transfusion. The positive rate of HBsAg was higher, but not significantly, in cases who had more than three siblings (0.05

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Factors influencing circadian rhythms in acetaminophen lethality

Experiments were conducted to examine the effects of changes in lighting schedules and food consumption on circadian rhythms in acetaminophen lethality and hepatic glutathione levels in male mice. Under a normal lighting schedule (light: 06.00-18.00 h), male mice exhibited a circadian rhythm in acetaminophen lethality (peak: 18.00 h; nadir: 06.00, 10.00 h) and an inverse rhythm in hepatic glutathione concentrations (peak: 06.00, 10.00 h; nadir: 18.00 h). Under a reversed lighting schedule (light: 18.00-06.00 h) the glutathione rhythm was reversed and the rhythm in acetaminophen lethality was altered showing greater sensitivity to the drug. Under continuous light, there was a shift in the acetaminophen lethality and the hepatic glutathione rhythms. Under continuous dark, both rhythms were abolished. Under a normal lighting regimen, hepatic glutathione levels were closely correlated with food consumption; i.e., both were increased during the dark phase and decreased during the light phase. Fasting the mice for 12 h abolished the rhythms in acetaminophen lethality and hepatic glutathione levels; moreover, the lethality was increased and the hepatic glutathione levels were decreased. These experiments show that both lighting schedules and feeding can alter the circadian rhythms in acetaminophen lethality and hepatic glutathione levels in male mice.

Estimation of respiratory impedance and source pressure using a Thévenin equivalent circuit model

The objective of this paper is to present a new technique which can provide both active respiration source pressure and lung impedance in a single noninvasive test. The method is based upon a Thévenin equivalent circuit model of respiratory mechanics. Using this model, the equivalent source pressure and source impedance can be computed from the measured changes of respiratory pressures and flows in two consecutive cycles before and after addition of purely resistive loads to the mouth. In maximal breathing the source parameters were reproducible in six normal human subjects. The total respiratory resistance during maximal breathing had an average value of 3.46 cmH2O l-1 s-1, and the total dynamic compliance had an average value of 0.078 l cmH2O-1. The airway resistances measured using a plethysmographic method were within the range of 45-65% of the estimated total respiratory resistances. These two resistances were related with a correlation coefficient of 0.98. An average value of the magnitudes of the fundamental components of the source pressure was 6.73 cmH2O during maximal breathing and 2.09 cmH2O during spontaneous breathing.

Polymorphism of red cell glutamic-pyruvic transaminase in Japanese: gene frequencies in samples from Northern Japan

The genetic polymorphism of red cell GPT was investigated by starch-gel electrophoresis in four samples from northern Japan including a sample of the Ainu of Hokkaido. The distribution of the Gpt1 gene frequencies among 10 samples excluding the Ainu so far examined showed heterogeneity. The geographical cline of Gpt1 gene frequency reported in southern Japan was not observed in northern Japan.