A novel missense mutation (Asn5-->Ile) in lecithin: cholesterol acyltransferase (LCAT) gene in a Japanese patient with LCAT deficiency

We identified a novel missense mutation in the lecithin:cholesterol acyltransferase gene in a new case of lecithin:cholesterol acyltransferase (LCAT) deficiency. The patient was a 64-year-old diabetic Japanese male who showed an extremely low level of serum high-density lipoprotein-cholesterol, corneal opacities, anemia, and proteinuria. Both the patient's LCAT activity and mass were markedly low. DNA sequence analysis of the LCAT gene showed an A-to-T transition at base 97 in exon 1, and predicted a change in asparagine to isoleucine at the 5th amino acid of the protein. Restriction analysis of polymerase chain reaction-amplified DNA using Ase I showed that the patient was homozygous for this mutation. Our results suggested that asparagine 5 was an important amino acid and substitution with isoleucine caused marked reduction of LCAT activity and mass, resulting in LCAT deficiency.

Clinicopathologic characteristics of hypertrophic cardiomyopathy detected during mass screening for heart disease

Between 1981 and 1992 a total of 10 patients with hypertrophic cardiomyopathy (HCM) were detected by mass screening for heart disease in Tokyo's Adachi Ward. Four were first grade elementary school children and six were first grade junior high school adolescents. Two-dimensional echocardiography at the initial evaluation revealed asymmetric septal hypertrophy in four patients, diffuse hypertrophy of the left ventricle in five, and poor left ventricular contractility with wall thinning in one (dilated phase). Three of the five patients with diffuse hypertrophy progressed to asymmetric septal hypertrophy during the average 4-year follow-up period. The degree of septal thickness and the left ventricular wall thickness index were significantly less than in those of young adult controls (12 +/- 3 versus 21 +/- 9 mm, p < 0.05; and 22 +/- 4 versus 28 +/- 16 mm, p < 0.05, respectively). Right ventricular endomyocardial biopsy specimens obtained from 9 of the 10 patients showed features typical of HCM (e.g., myocyte hypertrophy with myofibril disarray) in five patients and atypical features (mainly interstitial fibrosis with perivascular cell infiltration) in another four. One patient with dilated phase disease died of congestive heart failure 6 months after the initial evaluation. These results indicate that HCM detected during mass screening is a mild form of the disease and may have atypical pathologic features, such as interstitial fibrosis and perivascular cell infiltration, mimicking the sequela of chronic myocarditis.

A novel donor splice site mutation in the glycogen debranching enzyme gene is associated with glycogen storage disease type III

Analysis of glycogen debranching enzyme (debrancher) cDNA from a patient with glycogen storage disease type III revealed a deletion of 124 base pairs. A donor splice site mutation (IVS G+1 to T) was identified in the patient's debrancher gene, which caused exon skipping of the upstream exon and resulted in a truncated enzyme due to premature termination. Mutational analysis of the patient's family showed that this point mutation was inherited from the father. Southern blot analysis of the patient's genomic DNA showed an additional, unique EcoRI fragment of 5.8 kb, which was inherited from the mother. These results suggested that the patient was a compound heterozygote for the donor splice site mutation, which is the first identified in the debrancher gene, and had a genetic defect relating to an aberrant 5.8-kb EcoRI fragment.

Dose-dependent effect of niceritrol on plasma lipoprotein-a

Lipoprotein-a, Lp(a), is a variant form of low density lipoprotein (LDL) that contains apolipoprotein-a, whose structure has 75-85% homology with plasminogen. Elevated plasma levels of Lp(a) are considered to be one of the independent risk factors for cardiovascular disease. We studied the effects of niceritrol, a nicotinic acid derivative, on plasma Lp(a) levels in 72 patients with hypercholesterolaemia. The dose of niceritrol was increased every 4 weeks, from 750 to 1500 and then to 2250 mg day-1. The final dose was adjusted to obtain a plasma cholesterol level less than 5.69 mmol l-1. Niceritrol led to significant decreases in plasma levels of median Lp(a), from 16.1 mg dl-1 (interquartile intervals, 8.7 to 32.8) to 11.1 mg dl-1 (interquartile intervals, 6.6 to 21), the mean reduction rate being 17.6%. In the group with pretreatment Lp(a) levels of over 20 mg dl-1, Lp(a) decreased by 10.0, 22.0 and 31.8% at the doses of 750, 1500, and 2250 mg day-1, respectively. In the group with levels less than 20 mg dl-1, only the dose of 2250 mg day-1 was effective in the reduction of Lp(a). The results suggest that the reduction of Lp(a) was dependent on the dose of niceritrol and on the pretreatment level of Lp(a). In conclusion, niceritrol is effective, in a dose-dependent manner, for reducing Lp(a) levels.

Hypertriglyceridemia and low HDL cholesterol in Japanese patients with NIDDM

Diabetes is frequently associated with the combination of hypertriglyceridemia and low HDL cholesterol level, a known risk factor for cardiovascular disease. We evaluated the frequency of elevated serum triglyceride and the reduced HDL cholesterol levels in Japanese male NIDDM patients. Hypertriglyceridemia (>1.69 mmol/l) and low HDL cholesterol level (<0.91 mmol/l) were frequently found in Japanese male (NIDDM patients (30.4 and 14.2%, respectively). The combined abnormality, i.e., hypertriglyceridemia with concomitant low HDL cholesterol level, was more common in patients with poor glycemic control. We observed that inpatient diet therapy markedly reduced serum triglyceride but serum HDL cholesterol did not change significantly. This is in marked contrast to primary hypertriglyceridemia, in which HDL cholesterol level generally increases in parallel with a reduction in serum triglyceride level. We discuss the defective removal of triglyceride-rich lipoproteins and ineffective HDL production caused by lipoprotein lipase (LPL) deficiency. We also discuss possible correction of this combined abnormality by certain maneuvers that increase LPL activity.

Donor leukocyte transfusions and discontinuation of immunosuppressants to achieve an initial remission after allogeneic bone marrow transplantation in a patient with primary refractory acute leukemia

We present a female patient who received an allogeneic bone marrow transplantation for primary refractory Philadelphia-positive acute biphenotypic leukemia. Since leukemic blasts were persistently present in peripheral blood and bone marrow, in spite of the evidence for engraftment of male donor hematopoiesis, we performed donor leukocyte transfusions and discontinued immunosuppression. An initial complete remission was obtained 15 weeks after allogeneic bone marrow transplantation, and lasted for 24 weeks. We concluded that the prominent mechanism for the eradication of the refractory leukemic clone in the patient was the graft-versus-leukemia effect.

Increased serum concentrations of pro-gastrin-releasing peptide in patients with renal dysfunction

BACKGROUND

Gastrin-releasing peptide has a prominent role as a tumour marker in the diagnosis of small-cell lung carcinoma. This study was designed to assess the validity of a newly developed enzyme-linked immunosorbent assay (ELISA) for pro-gastrin-releasing peptide in patients with renal and systemic diseases.

METHODS

Pro-gastrin-releasing peptide concentrations in sera from normal subjects and patients with small-cell lung carcinoma, diabetes mellitus, rheumatoid arthritis, systemic lupus erythematosus, chronic glomerulonephritis, or undialysed or dialysed chronic renal failure were measured with the TND-4 Kit, a newly developed ELISA for pro-gastrin-releasing peptide.

RESULTS

All of the patients with normal renal function, whether they had diabetes mellitus (n=16), rheumatoid arthritis (n=10), systemic lupus erythematosus (n=12) or chronic glomerulonephritis (n=14), had serum pro-gastrin-releasing peptide concentrations less than 46 ng/l, the upper limit in normal subjects. In contrast, 14 or 16 patients (88%) with small-cell lung carcinoma, who had normal renal function, and 25 of 26 (96%) patients with chronic renal failure on haemodialysis had serum pro-gastrin-releasing peptide concentrations greater than 46 ng/l. The highest serum pro-gastrin-releasing peptide levels in patients with chronic renal failure, before and after initiating haemodialysis were 183 and 290 ng/l respectively. Ten of 16 (63%) small-cell lung carcinoma patients had serum pro-gastrin-releasing peptide concentrations greater than 290 ng/l, the highest level in haemodialysed patients. Serum pro-gastrin-releasing peptide concentrations were also elevated in patients with chronic glomerulonephritis or diabetes mellitus when their serum creatinine concentrations were greater than 120 micromol/l. And, there was a significant correlation, y=23.5+0.15x(n=22, r=0.82, P<0.001),between serum pro-gastrin-releasing peptide (y, in ng/l) and serum creatine (x in micromol/l) concentrations in those patients with renal dysfunction. The correlation between serum pro-gastrin-releasing peptide and serum urea nitrogen concentrations was likewise significant.

CONCLUSIONS

The evaluation of patients as to their renal functional state may be mandatory when serum pro-gastrin-releasing peptide levels are to be applied as one of the diagnostic tools for small-cell lung carcinoma or as a marker monitoring their clinical course.

Insulin stimulates protein synthesis of glycogen synthase in rat hepatoma H4 cells associated with acceleration of translation rate

To assess the regulatory mechanism of insulin action on the biosynthesis of glycogen synthase under long-term control, we investigated post-transcriptional and post-translational regulation by insulin of glycogen synthase in rat hepatoma H4 cells. Glycogen synthase protein gradually increased in response to insulin and peaked at 6 h during a 24-h insulin incubation (185% of the control), corresponding with the second peak of glycogen synthase activation measured by the activity ratio (low glucose 6-P/high glucose 6-P). The effect of insulin on synthesis of glycogen synthase protein was assessed by measuring the incorporation of [35S]-methionine into the enzyme protein during a 6-h insulin incubation. The amount of [35S]-methionine incorporation into glycogen synthase was increased in response to insulin with time, and peaked at 4 h (250% of the control). The degradation of glycogen synthase examined by measuring the rate of reduction of [35S]-methionine for 6 h after the tracer incubation for 12 h was not affected by insulin. The results indicate that (a) insulin induces glycogen synthase activity by accumulating the enzyme protein due to stimulation of protein synthesis rather than inhibition of protein degradation and (b) insulin-reduced stability of glycogen synthase mRNA is caused by acceleration of the translation rate.

Lipoprotein(a) is an independent risk factor for multiple cerebral infarctions

In an attempt to ascertain whether Lp(a) is a risk factor for multiple cerebral infarctions (MCI), we have studied 83 patients with proven MCI and 39 subjects without MCI by computed tomography (CT). Seventy-one patients with non-insulin-dependent diabetes mellitus (NIDDM) were included: 52 with and 19 without MCI. Serum Lp(a) levels were significantly higher in patients with MCI than in subjects without MCI. There were no differences in serum Lp(a) levels between NIDDM and non-diabetic patients with MCI. The logistic regression analysis revealed that Lp(a) and hypertension were independent risk factors for the cerebral event. The current study demonstrated that Lp(a) and hypertension are significant risk factors for multiple cerebral infarctions.

Enhancement of lymphokine-activated killer cell cytotoxicity implicated in the increased expression of surface adhesion molecules on tumor cells treated with anticancer agents

We investigated mechanisms underlying lymphokine-activated killer (LAK) cell cytotoxicity in terms of intensity of expression of intercellular adhesion molecule-1 (ICAM-1) and lymphocyte-function-associated antigen-3 (LFA-3) on Daudi and KATO-III cells treated with cis-diamminedichloroplatinum (II) (CDDP) and mitomycin-C (MMC). Enhancement (mean, 49.8%) of ICAM-1 or LFA-3 in mRNA and protein expression on treated tumor cells was found by flow cytometry, slot-blot RNA analysis, and reverse transcription-polymerase chain reaction (RT-PCR). Increases in adhesion and cytotoxicity of LAK cells to treated tumor cells were 10.1% and 17.7%, respectively. Results suggested that increased ICAM-1 or LFA-3 expression by low-dose CDDP or MMC binds LAK cells to tumor cells, helping to kill tumor cells. Thus, LAK cell therapy with anticancer agent pretreatment could be useful for treatment of cancer patients.