Tadashi Hoshino

Frequency of exon 15 missense mutation (442D:G) in cholesteryl ester transfer protein gene in hyperalphalipoproteinemic Japanese subjects

Cholesteryl ester transfer protein (CETP) transfers cholesteryl ester from high density lipoprotein (HDL) to apo B-containing lipoproteins. The hyperalphalipoproteinemia caused by CETP deficiency is fairly common in Japan and one of the most common mutations in the CETP gene is the splicing defect of the intron 14, the allelic frequency of which has been shown to be 0.0049 in the Japanese general population. Recently, we have reported a missense mutation in exon 15 of the CETP gene (442D:G), showing a dominant effect on the CETP activity and HDL-cholesterol level. In the current study, we determined the frequency of this new mutation in Japanese hyperalphalipoproteinemic (HDL-cholesterol > or = 100 mg/dl) subjects. A rapid and easy screening method for this new mutation was developed using a polymerase chain reaction (PCR)-mediated site-directed mutagenesis. Among 117 Japanese hyperalphalipoproteinemic subjects (HDL-cholesterol; 116.7 +/- 16.5 mg/dl, mean +/- S.D.) without the intron 14 splice defect, three homozygotes (2.5%) and 34 heterozygotes (29.1%) were found to have the 442D:G mutation. The relative allelic frequency of this mutation was calculated to be 0.17. One of the homozygotes for the 442D:G mutation was the patient previously described by us as having hyperalphalipoproteinemia with corneal opacity and coronary heart disease. This was the first reported subject homozygous for the CETP deficiency who also demonstrated atherosclerotic symptoms. In homozygous subjects, CETP activity ranged from 37% to 62% of the normal value, which was consistent with the results obtained from the transient expression experiment previously reported; however, the specific activity of CETP was not as low as expected.(ABSTRACT TRUNCATED AT 250 WORDS)

Frequency of intron 14 splicing defect of cholesteryl ester transfer protein gene in the Japanese general population — relation between the mutation and hyperalphalipoproteinemia

Cholesteryl ester transfer protein (CETP) deficiency, which has been found only in Japan, is characterized by marked hyperalphalipoproteinemia (HALP) and abnormalities of both low density and high density lipoproteins. We have reported that this deficiency is commonly associated with a G-->A mutation at the intron 14 splice donor site of the CETP gene (Yamashita et al., Biochem. Biophys. Res. Commun., 170 (1990) 1346-1351). In the current study, we determined the frequency of this mutation in Japanese subjects by using polymerase chain reaction. A single primer-template mismatch of one base pair from the CETP gene mutation permitted the introduction of a cleavage site for Nde I in mutant alleles but not in normal ones. Out of 171 patients with marked HALP whose serum HDL-cholesterol was more than 100 mg/dl, 6 (3.5%) subjects were homozygous and 48 (28.1%) were heterozygous for this mutation. Furthermore, in unrelated 512 healthy Japanese subjects, 5 (0.98%) were identified as heterozygotes. Relative allelic frequency of A at the intron 14 splice donor site was 0.0049 and the frequency of homozygous CETP deficiency was estimated to be approximately 1/42,000. These results demonstrate that this common mutation may be frequent in the Japanese population. Although HALP is very heterogenous, this mutation could be one of the major causes of marked HALP.

Development and performance of an enzyme immunoassay to detect creatine kinase isoenzyme MB activity using anti-mitochondrial creatine kinase monoclonal antibodies

Abstract Objective: The MB fraction of creatine kinase (CK-MB) has long been used as a cardiac marker. It is known that the CK-MB immunoinhibition method lacks selectivity and accuracy, because the appearance of macro CK type 2, corresponding to mitochondrial creatine kinase (MtCK) in some patient serum may render CK-MB activity measured by conventional method abnormally high. Thus, to improve the specificity and accuracy of the CK-MB assay, we developed two types of monoclonal anti-MtCK antibodies against sarcomeric MtCK and ubiquitous MtCK, and present herein the performance of a new method using these antibodies. Material and methods: The performance of our test for detecting CK-MB activity was compared with other methods, and the range of CK-MB activities in normal human serum was investigated. Results: The two types of monoclonal antibodies developed by us were isoenzyme-specific to sMtCK or uMtCK. The correlation coefficients of our method and conventional method to electrophoresis were 0.973 and 0.873, respectively. The mean CK-MB activity in normal human serum by our method and the conventional method was 2.4 and 11.7 U/L, respectively. Thus, our data indicated that about 80% of CK-MB activity, determined using the conventional method, seems to correspond to the MtCK activity. Conclusion: Our method is novel in offering higher accuracy of measuring true CK-MB contents in human serum as compared to the conventional method. The possibility of accurately estimating CK-MB activity by our method which can inhibit MtCKs in healthy person and patient serum is likely to bring a break-through in clinical diagnostics.

A case of Benign familial hyperphosphatasemia of intestinal origin

We recently encountered a case of hyperphosphatasemia, in which > 90% of serum alkaline phosphatase (ALP) was of intestinal origin. The patient, a 51-year-old man, was found to have hyperphosphatasemia (2,341 U/L) during a routine medical check-up. All other laboratory tests and physical findings were normal. The agarose gel electrophoresis pattern of the patients serum ALP was identical to that of common intestinal ALP from healthy adults, and only a single band of intestinal ALP was detected by immunoaffinity electrophoresis. In addition, 89% of total ALP was defined as intestinal ALP by an immunoprecipitation method. The molecular mass of the ALP was 154 kDa, almost identical with that of adult duodenal ALP. Analysis of the sugar chain structure showed an increased la fraction (74%) compared with adult duodenal ALP. Genealogical study revealed that two persons in the 5 members of the probands family had hyperphosphatasemia of intestinal origin, indicating possible autosomal dominant inheritance.

Abnormal alkaline phosphatase of hepatic type in cerebrospinal fluid of a patient with intracranial metastasis from lung cancer.

High alkaline phosphatase (ALP) activity was found in the cerebrospinal fluid of a patient with intracranial metastases from adenocarcinoma of the lung. On agarose gel electrophoresis of the major ALP isoenzyme found in the cerebrospinal fluid, its mobility was different from those of the usual serum ALP isoenzymes. This abnormal mobility might be due to the linked glycan phosphatidylinositol anchor in the ALP molecule, as the mobility became the same as that of the common liver type ALP after treatment with phosphatidylinositol specific phospholipase. The immunochemical antigenicity of the cerebrospinal fluid ALP was identical with that of the common serum liver type ALP, but its sugar moiety was similar to the membranous liver-type ALP rather than the serum liver type ALP. The molecular size of the cerebrospinal fluid ALP was 140 kilodaltons, 12 less than the common serum liver type ALP, suggesting that the ALP in the patients cerebrospinal fluid was derived from the intracranial metastatic carcinoma.

Evaluation of Serological Diagnosis Tests for Tuberculosis in Hemodialysis Patients

Abstract:  Patients receiving hemodialysis are generally considered to be at increased risk of developing tuberculosis. In the current study, in order to evaluate the usefulness of serological tests in dialysis patients, serum antibodies for tuberculous glycolipids antigen (TBGL) and for lipoarabinomannan (LAM) were measured in hemodialysis patients. The present study included 243 hemodialysis patients. Serum antibodies for TBGL and LAM were measured. Tuberculin skin tests were carried out and chest X‐rays evaluated at the same time. There were no patients with active tuberculosis at the time of blood sampling. Thirty‐six patients (14.8%) and 25 patients (10.3%) were positive for anti‐TBGL antibody and anti‐LAM antibody, respectively. One hundred and fifty‐five patients (63.8%) were positive for tuberculin skin testing and 123 patients (50.6%) had old pulmonary tuberculosis on their chest X‐ray. There was no significant correlation between the results of anti‐TBGL antibody and anti‐LAM antibody. There were no relationships among the results of tuberculin skin test and the two serological tests. However, positivity of anti‐TBGL antibody and anti‐LAM antibody was significantly higher in patients with findings of old tuberculosis on the chest X‐ray than those without findings. The current results show that these serological tests are positive more frequently in hemodialysis patients without any proof of active tuberculosis than in healthy subjects (2%) and careful interpretation is necessary for relevant results.

Increased activity of serum mitochondrial isoenzyme of creatine kinase in hepatocellular carcinoma patients predominantly with recurrence

BACKGROUND & AIMS Mitochondrial isoenzyme of creatine kinase (MtCK) is reportedly highly expressed in hepatocellular carcinoma (HCC). Clinical relevance of serum MtCK activity in patients with HCC was assessed using a novel immuno-inhibition method. METHODS Among patients with cirrhosis caused by hepatitis B or C virus, 147 patients with HCC (12 with the first occurrence and 135 with recurrence) and 92 patients without HCC were enrolled. RESULTS Serum MtCK activity was higher in cirrhotic patients with HCC than in those without HCC or healthy subjects. Elevated serum MtCK activity in HCC patients decreased after radiofrequency ablation. In case of prediction of HCC, MtCK had a sensitivity of 62.6% and a specificity of 70.7% at a cut-off point of 8.0 U/L, with an area under the receiver operating curve of 0.722 vs. 0.713 for alpha-fetoprotein (AFP) and 0.764 for des-gamma-carboxy prothrombin (DCP). Among the HCC patients, serum MtCK activity was elevated in 52.9% individuals with serum AFP level < 20 ng/ml and 63.2% individuals with serum DCP level < 40 mAu/ml. Even in patients with a single HCC ≤ 2 cm, the sensitivity of serum MtCK activity for the prediction of HCC was 64.4%, which was comparable to the overall sensitivity. This increased activity was due to an increase in ubiquitous MtCK, not sarcomeric MtCK, and the enhanced mRNA expression of ubiquitous MtCK was observed in cell lines originating from HCCs in contrast to healthy liver tissues. CONCLUSIONS Serum MtCK activity merits consideration as a novel marker for HCC to be further tested as for its diagnostic and prognostic power.

Properties of IgG conjugated with LDH having slowγ mobility

We have described a case of Lactate dehydrogenase (LDH) linked to IgG (kappa) immunoglobulin which LDH isoenzyme pattern shows as if six bands are present. Of these bands, one additional is located at slow gamma region and such an anomalous appearance has not previously reported. The serum contains monoclonal immunoglobulin G (kappa) of which electrophoretic mobility is at slow gamma region (same as for abnormal LDH).From reconstitution experiments, we concluded that all five LDH isoenzymes could bind to IgG prepared from the patient and those mobilities of the linked LDHs changed to cathodic side; LDH1, tailed to cathodic side; LDH2, moved to cathodic side; LDH3, located at slow LDH4; LDH4 located at fast LDH5; LDH5, located it slow gamma region; respectively. The affinity constant of each LDH isoenzyme was estimated and the values obtained from LDH1 to 5 were 0.026, 0.079, 0.166, 3.715, and 0.218. (Keg×109 liters/mol) was respectively. LDH4 evoked the highest affinity, it suggests that the site of antigen recognition of LDH linked to IgG was not associated with the structure of individual LDH-H and LDH-M subunits.