Molecular basis of hereditary methaemoglobinaemia, types I and II: two novel mutations in the NADH-cytochrome b5 reductase gene

Hereditary methaemoglobinaemia, caused by deficiency of NADH-cytochrome b₅ reductase (b5R), has been classified into two types, an erythrocyte (type I) and a generalized (type II). We analysed the b5R gene of two Thai patients and found two novel mutations. The patient with type II was homozygous for a C-to-T substitution in codon 83 that changes Arg (CGA) to a stop codon (TGA), resulting in a truncated b5R without the catalytic portion. The patient with type I was homozygous for a C-to-T substitution in codon 178 causing replacement of Ala (GCG) with Val (GTG). To characterize effects of this missense mutation, we investigated enzymatic properties of mutant b5R (Ala 178 Val). Although the mutant enzyme showed normal catalytic activity, less stability and different spectra were observed. These results suggest that this substitution influenced enzyme stability due to the slight change of structure. In conclusion, the nonsense mutation led to type II because of malfunction of the truncated protein. On the other hand, the missense mutation caused type I, due to degradation of the unstable mutant enzyme with normal activities in patient's erythrocytes, because of the lack of compensation by new protein synthesis during the long life-span of erythrocytes.     

Study for determination of the optimal cessation period of therapy with anti-platelet agents prior to invasive endoscopic procedures

Background Anti-platelet agents are widely used for the treatment and prevention of thrombotic diseases. On the other hand, continuation of anti-platelet agents increases the risk of hemorrhagic complications in gastrointestinal endoscopy, and cessation of anti-platelet agents exposes the patient to the risk of thromboembolism. Only a few studies have actually studied the whether a cessation period is required prior to endoscopic procedures and if so, the optional duration of the period. The present study assessed the time course of primary hemostasis after the cessation of anti-platelet agents.Methods Eleven healthy men (age range, 19–29 years) were assigned to each of the following regimens: aspirin (ASA; 100 mg/day), ticlopidine (TP; 300 mg/day), and a combination of ASA (100 mg/day) and TP (300 mg/day) for 7 days. There was a washout period of more than 3 weeks between each regimen. A quantitative bleeding time test (QBT test) and platelet aggregation test were performed before the beginning of administration, on the last day of administration, and at 1, 3, and 5 days after cessation, and also at 7 days after cessation for the combination regimen.Results The average bleeding time (BT) and total bleeding loss volume (Tv) of the 11 subjects after administration of the three regimens were significantly increased compared with those before administration. With the administration of ASA, increases of BT and Tv at 3 days after cessation were not significant. The Tv at 5 days after cessation of TP was not significantly increased. With the combination regimen, the BT and Tv at 7 days after cessation were not significantly increased.Conclusions A 3-day cessation period for ASA, a 5-day cessation period for TP, and a 7-day cessation period for ASA + TP administration seem to be sufficient.     

Diagnosis and assessment of monkeypox virus (MPXV) infection by quantitative PCR assay: differentiation of Congo Basin and West African MPXV strains

Human monkeypox, an infectious disease caused by monkeypox virus (MPXV), is endemic to western and central Africa. A LightCycler quantitative PCR (LC-qPCR) system was developed for the diagnosis of this disease, targeting the A-type inclusion body gene (ATI gene) of MPXV. One naive monkey was infected with MPXV Zr-599 (Congo Basin strain) and one with MPXV Liberia (West African strain). Another three monkeys were immunized with smallpox vaccine on 0, 3, or 7 days, respectively, before infection with MPXV Zr-599. Peripheral blood cell (PBC) and throat swab (TS) specimens were serially collected. The LC-qPCR was validated for the diagnosis of monkeypox using virus isolation. Sequencing of the partial ATI gene revealed the insertion of a unique 453-nucleotide residue in the West African strains but not in the Congo Basin strains. Specific reverse primers for Congo Basin and West African strains were designed based on the unique sequence insertion. The LC-qPCR detected the MPXV genome, but not those of the other orthopoxviruses tested nor the varicella-zoster virus. Both the sensitivity and specificity of the LC-qPCR were over 90% in comparison to virus isolation when TS specimens were tested. Fourteen of the 15 virus isolation-positive PBC specimens showed positive reactions in the assay. Further, most PBC specimens collected from symptomatic monkeys in the later stage of illness showed positive reactions in the assay but negative reaction in virus isolation. It was possible to differentiate between these two groups with the LC-qPCR. Thus, the newly developed LC-qPCR is a useful and reliable diagnostic tool for MPXV infection.     

Effect of infarcted myocardium on diagnostic accuracy of exercise echocardiography for detecting noninfarct-related coronary artery lesions

Background The utility of exercise echocardiography for evaluating remote ischemia due to noninfarct-related artery (n-IRA) lesions in patients with prior myocardial infarction has not been established.Methods Quantitative coronary angiography and treadmill exercise echocardiography were performed within 2 weeks in 115 patients with prior myocardial infarction (>6 weeks) and 224 patients without myocardial infarction. Coronary lumen diameter stenosis ≥50% (by angiography) and the lack of a hyperdynamic response on exercise echocardiography were considered significant. Myocardial infarction size was defined as the number of myocardial segments with severe hypokinesis, akinesis, or dyskinesis on echocardiography at rest.Results For detection of n-IRA lesions in patients with prior myocardial infarction, the sensitivity of exercise echocardiography was similar (78% vs 79%, P = not significant), however, the specificity was significantly lower (77% vs 91%, P < .01) than for detection of significant stenoses in patients without prior myocardial infarction. Angiographic percent-diameter stenosis, presence of collateral vessel, achieved exercise level, and presence of peri-infarct ischemia did not affect the specificity of exercise echocardiography. However, the specificity of exercise echocardiography was significantly lower (69% vs 84%, P < .05) in patients with echocardiographically large infarction (infarction size ≥2) than in patients with small infarction (infarction size <2).Conclusion In patients with prior myocardial infarction, exercise echocardiography showed low specificity for detection of noninfarct-related artery lesions, especially in patients with echocardiographically large myocardial infarction. These characteristics of treadmill exercise echocardiography should be considered when this technique is applied for patients with healed myocardial infarction. (Am Heart J 2003;145:162-8.)     

Unmyelinated fiber sensory neuropathy differs in type 1 and type 2 diabetes

BACKGROUND: Neuropathic pain is common in diabetic patients. Degeneration of sensory C-fibers in peripheral nerve plays a prominent role in the generation of neuropathic pain. We examined degenerative changes of C-fibers in two rat models with type 1 and type 2 diabetes. METHODS: Type 1 insulinopenic BB/Wor and type 2 hyperinsulinemic diabetic BBZDR/Wor-rats of 8 months duration with equal exposure to hyperglycemia were examined. Thermal hyperalgesia was monitored using an infrared thermal probe. C-fiber size, number, frequencies of denervated Schwann cells, regenerating C-fibers, type 2 axon/Schwann cell relationship and collagen pockets in the sural nerve were examined morphometrically. Neurotrophic receptor expression was examined by Western blotting. Neurotrophins and neuropeptides were examined by ELISA. RESULTS: Type 1 rats showed increased thermal hyperalgesia followed by a decrease. Hyperalgesia in type 2 rats showed a slower progression. These findings were associated with a 50% (p < 0.001) loss of C-fibers, increased frequencies of denervated Schwann cells (p < 0.001), regenerating fibers (p < 0.001), collagen pockets (p < 0.001) and type 2 axon/Schwann cell relationship (p < 0.001) in type 1, but not in type 2 rats. Expression of insulin receptor, IGF-1R, TrkA and C was decreased in BB/Wor rats, whereas BBZDR/Wor rats showed milder or no deficits. NGF and NT-3 in sciatic nerve and substance P and calcitonin gene-related peptide in dorsal root ganglia were decreased in type 1, but not in type 2 rats. CONCLUSION: The more severe molecular, functional and morphometric abnormalities of nociceptive C-fibers in type 1 insulinopenic rats compared to type 2 hyperinsulinemic rats suggest that impaired insulin action may play a more important pathogenetic role than hyperglycemia per se.     

Effect of statin on restenosis after radius stent implantation in patients with acute coronary syndrome

Despite reports that statin treatment reduces the rate of coronary restenosis with a balloon expandable stent, there is no evidence that statins affect the incidence of restenosis with a self-expanding Radius stent. Ninety-five patients with acute coronary syndrome who had been implanted with a Radius stent were classified into two groups: those with hyperlipidemia and initial statin treatment (statin group, n = 38) and those without statin treatment (comparative group, n = 57). At six months after stent implantation, the rate of coronary restenosis was significantly lower in the statin group (10.5%) than control group (28.1%) (p = 0.033), while there were no differences in morphology, maximal inflation pressure or stent size between the two groups. Interestingly, there was no difference in the serum lipid profile between the two groups at the 6-month follow-up, although the statin group had a significantly lower rate of restenosis. In conclusion, initial statin therapy reduced the rate of coronary restenosis even when a Radius stent was implanted.     

Hepatitis B virus markers and antibodies to hepatitis C virus in Japanese patients with hepatocellular carcinoma

Sera from Japanese patients with chronic liver disease were tested for hepatitis B virus (HBV) markers and antibodies to hepatitis C virus (anti-HCV), and the results were correlated to the presence of hepatocellular carcinoma. In chronic non-A, non-B liver disease, anti-HCV prevalence was high both in patients with hepatocellular carcinoma (78/89, 88%) and without it (66/84, 79%), while previous HBV infection was more common in patients with hepatocellular carcinoma (65/89, 73%) than in those without it (46/84, 55%) (P<0.05). Coexistence of anti-HCV and antibodies to HBV was observed frequently in patients with hepatocellular carcinoma (56/89, 63%) compared with patients without it (39/84, 46%) (P<0.05). In chronic HBV carriers, anti-HCV was more common in patients with hepatocellular carcinoma (12/38, 32%) than in those without it (3/62, 5%) (P<0.01). These results suggest that infection with the two viruses may be a risk factor for more serious liver disease.This work was supported by a Grant-in-Aid from the Ministry of Education, Science and Culture, Japan.     

Subacute cor pulmonale due to tumor embolism

We describe a patient wih subacute cor pulmonale caused by tumor emboli in the lungs. A 64-year-old female suffering from a subacute progressive cough and shortness of breathing died of severe pulmonary hypertension seven days after admission. Neither chest CT scans nor lung perfusion scintigraphy showed any abnormal findings. Microscopic examination after an autopsy revealed diffuse intravascular tumor emboli occluding not only the small pulmonary arteries and arterioles, but also the lymphatic vessels, which were suggested to be metastases of a breast carcinoma resected five years previously. Thus, pulmonary tumor embolism should be considered in the differential diagnosis of primary pulmonary hypertension, particularly in patients with a past history of cancers.     

Quantitative magnetic resonance perfusion imaging detects anatomic and physiologic coronary artery disease as measured by coronary angiography and fractional flow reserve.

OBJECTIVES: To evaluate the ability of quantitative perfusion cardiac magnetic resonance (CMR) to assess the hemodynamic significance of coronary artery disease (CAD) compared with well-established anatomic and physiologic techniques. BACKGROUND: Fractional flow reserve (FFR) is considered by many investigators to be a reliable stenosis-specific method to determine hemodynamically significant CAD. Quantitative perfusion CMR is a promising noninvasive approach to detect CAD but has yet to be validated against FFR. METHODS: This is a prospective study in patients with suspected CAD who underwent coronary angiography, FFR, and CMR assessments. The quantitative myocardial perfusion reserve (MPR) was calculated in 720 myocardial sectors (8 sectors/slice). The MPR was calculated from the ratio between stress and rest myocardial flow based on signal intensity time curves using deconvolution analysis. Stress was simulated with adenosine for both FFR and MPR. The MPR assessments were compared to FFR (n = 44 coronary segments) and quantitative coronary angiography (n = 108 segments) in the corresponding coronary territories. RESULTS: The MPR was 1.54 +/- 0.36 in segments with FFR < or =0.75 (n = 14) and 2.11 +/- 0.68 in those with FFR >0.75 (n = 30; p = 0.0054). An MPR cutoff of 2.04 was 92.9% (95% CI 77.9 to 100.0) sensitive and 56.7% (95% CI 32.8 to 80.6) specific in predicting a coronary segment with FFR < or =0.75. The MPR was 1.54 +/- 0.49 in coronary segments with > or =50% diameter stenosis (DS) (n = 47) and 2.13 +/- 0.80 in segments with <50% DS (n = 61; p < 0.001). An MPR cutoff of 2.04 was 85.1% (95% CI 71.1 to 99.2) sensitive and 49.2% (95% CI 33.6 to 64.8) specific in predicting CAD with > or =50% DS. CONCLUSIONS: Quantitative perfusion CMR is a safe noninvasive test that represents a stenosis-specific alternative to determine the hemodynamic significance of CAD.