Noriyuki Nagata

Four-hydroxyphenylpyruvic acid oxidase deficiency with normal fumarylacetoacetase: a new variant form of hereditary hypertyrosinemia.

Summary: Enzymatic studies on the liver of an infant are described-a case of hypertyrosinemia without hepatic dysfunction. His parents were siblings and the mother had hypertyrosinemia. Excessive amounts of 4-hydroxyphenylpyruvic acid (pHPP), 4-hydroxyphenylacetic acid (pHPL), and 4-hydroxyphenylacetic acid (pHPA) were found to be excreted in the patients urine as well as in the urine of the mother and the inhibitor of porphobilinogen synthetase was not found. Soluble tyrosine aminotransferase (s-TAT), separated from that of the mitochondrial form (m-TAT) by DE 52 column chromatography, was normal in the patients liver, both quantitatively and qualitatively. The activities of fumarylacetoacetase in the patients liver and in the peripheral leucocytes from the parents were normal. The activity of pHPP oxidase in the patients liver was approximately 5% of the control and the enzyme had a high Km value for pHPP (controls: 0.06 ± 0.01 mM, patient: 0.23 ± 0.03 mM). From these results, the patient was thought to be different from previously described types of tyrosinemia and perhaps representative of a new variant form.This is the first report concerning 4-hydroxyphenylpyruvic acid oxidase deficiency alone. Mild metal retardation and mild hypertyrosinemia may be offered as typical clinical features of the disease.

Fractional esterification rate of cholesterol in high density lipoprotein (HDL) can predict the particle size of low density lipoprotein and HDL in patients with coronary heart disease

Fractional esterification rate of cholesterol in high density lipoprotein (HDL) (FER[HDL]) can predict the size distribution and physicochemical characteristics of HDL in plasma. In the present study, we investigated the correlation of FER(HDL) with the particle size of low density lipoprotein (LDL) (LDL-size) in 111 patients (81 males and 30 females) with coronary heart disease (CHD). The correlations of FER(HDL) and LDL-size with conventional lipid and lipoprotein parameters were also studied. FER(HDL) was closely associated with LDL-size (males: r = -0.618, females: r = -0.629, P < 0.001). Plasma levels of TG, HDL-cholesterol (HDL-C), HDL2-cholesterol (HDL2-C) and apo B were also associated with LDL-size in male CHD patients (r = -0.534, 0.314, 0.358, and -0.482, P < 0.01 or 0.001), while plasma levels of TG and apo B were associated with LDL-size in female patients (r = -0.350 and -0.348, P < 0.05). In a stepwise multiple regression analysis, FER(HDL) alone accounted for 38 and 40% of the variability in LDL-size in male and female CHD patients, respectively. Other parameters accounted for an additional 6-10%. With respect to the relation between FER(HDL) and HDL subfractions, FER(HDL) related only to HDL2-C (males: r = -0.640, females: r = -0.652, P < 0.001). This result suggests that FER(HDL) is better able to predict the presence (or absence) of large HDL, rather than that of small HDL. All these data taken together, suggest that FER(HDL) is a useful tool to predict the particle size of both LDL and HDL, even in CHD patients.

The infantile form of sialidosis type II associated with congenital adrenal hyperplasia: Possible linkage between HLA and the neuraminidase deficiency gene

SummaryThe possible genetic linkage between HLA and neuraminidase deficiency was studied in a female patient with combined abnormalities of the infantile form of sialidosis type II and congenital adrenal hyperplasia caused by 21-hydroxylase deficiency, and six members of her family. Her parents were consanguineous. The patient has the homozygous HLA haplotypes, TS-1, Cw3, DRw9. Four of the tested family members, including a distant male relative with congenital adrenal hyperplasia, were heterozygous of this HLA complex, and the neuraminidase activities in their skin fibroblasts and/or lymphocytes showed values between those of the patient and controls (25–48%), suggesting a carrier state of sialidosis. This indicates that the neuraminidase deficiency gene, similar to the 21-hydroxylase deficiency gene, is closely linked to the HLA genotype and is located on chromosome 6.

Biochemical heterogeneity of ornithine carbamoyl transferase(OCT) in patients with OCT deficiency

SummaryThe biochemical heterogeneity of ornithine carbamoyltransferase (OCT) was investigated in one male and three female patients with OCT deficienty. OCT from the male patient showed extremely low activity and no immunologically cross-reactive material (CRM) against antihuman liver OCT antibody. Residual OCT in two female patients was similar, being approximately 10% of the control with regard to both the activity and the amount of CRM. Their kinetic parameters were identical to those of the control. The enzyme activity and amount of CRM in the last female patient were 22.5% and 48.5% of the control, respectively. Thus, it is likely that gene mutation caused a reduction of enzyme protein or production of a distinctly unstable enzyme in the former three patients and a structural gene mutation produced a mutant OCT in the last patients.

Skin histidase activity and urine formiminoglutamic acid (FIGLU) in patients with histidinemia found by screening newborn infants

Skin histidase activities and urine formiminoglutamic acid (FIGLU) levels were measured in 20 patients with histidinemia, identified by Guthries screening method, and their family members as well as control subjects. There was a significant positive correlation between skin histidase activities and the amounts of urine FIGLU. Although the difference of skin histidase activity and the amount of urinary FIGLU was significant between any two of the three groups (i.e. controls, parents and patients; p less than 0.005), these levels ranged widely and a considerable number of the cases overlapped among groups. When a discriminant function was computed to obtain the minimum probability of misclassification between the groups using the above two parameters, a better segregation was observed. However, even though the number of misclassifications decreased, the overlapping cases were still present, especially between the parent and patient groups. It is concluded that either skin histidase activity, urine FIGLU, or both, can be used as genetic markers of the disease to a large but still limited extent.

Zinc status of untreated histidinemic children

Summary: In order to study zinc status in histidinemia, serum and hair zinc cocentrations were measured in 40 untreated children with histidinemia (age 2 months-5 years). In 20 children (> 2 years of age) zinc content and carbonic anhydrase activity of erythrocytes and urinary excretion of zinc were also studied. The amount of zinc excreted was elevated in histidinemic children and showed a positive correlation with the urinary histidine concentration (γ = 0.57, p < 0.005). The means of serum zinc concentration, erythrocyte zinc concentration, and erythrocyte carbonic anhydrase activity were all similar in the histidinemic and the control children. Hair zinc concentration of histidinemic children was compared with that of controls of five different age groups: <5 months, 5–18 months, 18 months-2 years, 2–4 years, and 4–5 years. In all of these age groups, hair zinc content was similar. The incidence of low-hair-zinc level (<80 μg/g) in histidinemic children >5 months of age (9 of 34) was significantly higher than in controls (18 of 180, p < 0.05). The observation suggested the possibility that untreated histidinemia may cause chronic mild zinc deficiency in some histidinemic children.

Effects of dietary zinc deficiency on hepatic ornithine carbamoyltransferase and alcohol dehydrogenase activities in rats

Hepatic ornithine carbamoyltransferase (OCT) and alcohol dehydrogenase (ADH) activities were measured in six groups of rats: (A) fed a severe zinc-(Zn-) deficient diet (1.98 ppm) for 5 weeks; (B) pair-fed control for group (A); (C) fed a less severe Zn-deficient diet (6.10 ppm) for 5 weeks; (D) pair-fed control for group (C); (E) fed a Zn-supplemented control diet (90.4 ppm) for 5 weeks; and (F) first fed the severe Zn-deficient diet for 5 weeks and then replaced on the Zn-supplemented control diet until a body weight corresponding to the final weight of group (E) was obtained. Hepatic OCT was similar in all these six groups. On the contrary, hepatic ADH was significantly reduced in groups (A) and (C) and in each of the corresponding pair-fed groups, (B) and (D). No differences were found between groups (A) and (B) or between groups (C) and (D). In group (F), ADH activity improved to a level equivalent to that in group (E). The changes in ADH activities were accompanied by changes in the hepatic Zn content. Thus, it is clear that: (1) the hepatic Zn content may not be affected by the amount of Zn intake alone, but by the combination of Zn and food intake; and (2) ADH, and not OCT, reflected the hepatic Zn content.

Lysine intolerance in a variant form of citrullinemia.

Summary: An oral loading of lysine (100 mg of lysine-HCL/kg) was performed in two patients, 18-and 23-yr-old, with a variant form of citrullinemia.Serum citrulline levels were approximately 10 times higher than control level and lysine levels were within the normal range, in contrast to the classical form of the disease in which serum citrulline is approximately 100 times normal levels and hyperlysinemia is usually present.After lysine loading, lysine levels rose sharply and clearance was decreased. Blood ammonia rose approximately 2.5 times. Lysine, citrulline, and arginine were markedly elevated in urine, collected 90–210 min after the lysine loading. Baseline homocitrulline and homoarginine excretion was elevated and increased further after the load.Speculation: Lysine tolerance was impaired in two patients with citrullinemia, although baseline lysine levels were normal. Lysine seemed to be catabolized along the alternate urea cycle: lysine-homocitrulline-homoarginine-urea. Hyperammpnemia was aggravated, suggesting competition between lysine and ammonia for α-ketoglutarate and inability to remove ammonia completely by these two alternate pathways

Ornithine transcarbamylase (OTC) in white blood cells

Summary: A radiochemical assay method of ornithine transcarbamylase (OTC) was developed using labeled carbamyl phosphate as a substrate. The enzyme activities determined by this method in peripheral white blood cells from ten normal subjects were 1.32 ± 0.95 nmoles/mg/hr and the apparent Kms, when assayed at pH 8.5, were 6.4 mM for ornithine and 0.6 mM for carbamyl phosphate. On the contrary, the apparent Kms of human liver OTC were 0.6 mM for ornithine and 0.12 mM for carbamyl phosphate. The average OTC activity of granulocytes was 1.0 nmoles/mg/hr, whereas that of mononuclear cells was 0.4 nmoles/mg/hr.Lymphoid cell lines were established from three normal subjects and an OTC-deficient infant. All these cell lines demonstrated no OTC activity. When arginine was removed from the medium and replaced by ornithine, the lymphoid cells were unable to grow in culture. On autoradiography, the lymphoid cells showed labeling at incubation in the presence of 14C-citrulline, but not with 14C-ornithine.Speculation: The wide range of OTC activities observed in white blood cells from normal subjects might be due to a difference of the enzyme activities between granulocytes and mononuclear cells and in turn due to an individual difference of the two cell population. OTC is either absent or inactivated in lymphoid cell lines, when grown in a culture medium with arginine. The enzyme of the peripheral white blood cells might be of a different genetic origin from that of the liver.

Sural nerve lesions in a case of hypertyrosinemia

A sural nerve obtained three hours after death from a patient with hypertyrosinemia due to 4-hydroxyphenylpyruvic acid oxidase deficiency was examined. The diameter of the myelinated fibers, as seen on the histogram, was similar to those in an age matched control. However, the number of smaller fibers was greater. Electron-microscopically, the findings of de- and hypomyelination were noted, and occasional dense bodies and multimembranous bodies were seen in some axoplasms. Since his mother was also suffering from hypertyrosinemia, the serum tyrosine level during the fetal and newborn infant periods seemed to be constantly elevated, which may have caused the abnormalities of nerve fibers observed in the present case.