Cerebral blood flow measurement with iodine-123-IMP SPECT, calibrated standard input function and venous blood sampling

We previously reported simple methods for measuring cerebral blood flow (CBF) with 123l-labeled N-isopropyl-p-iodoamphetamine (IMP) and SPECT: table look-up method and autoradiography. With these methods, the arterial input function is obtained by calibrating the standard input function using one-point arterial blood sampling 10 min after IMP infusion. In this study, we sought to determine if these approaches can be as successful when used with venous blood sampling.

METHODS

After IMP infusion, simultaneous arterial and venous blood samples were drawn from 30 subjects without heart or lung disease.

RESULTS

The activity ratios of venous whole blood from the cubital vein to arterial blood were 0.75 +/- 0.09, 0.77 +/- 0.10, 0.78 +/- 0.03 and 0.83 +/- 0.11, respectively, at 10, 20, 30 and 50 min after IMP infusion. Venous blood activities were always 20% lower than the artery values over 50 min. When blood was sampled from the dorsal hand vein, however, the respective ratios were 0.92 +/- 0.03, 0.93 +/- 0.05, 0.97 +/- 0.04 and 0.98 +/- 0.08 after 10, 20, 30 and 50 min. Furthermore, when the palm was exposed to heat during the sampling period, blood activity levels increased to 0.92 +/- 0.04, 0.96 +/- 0.04, 0.99 +/- 0.05 and 0.98 +/- 0.03. Thus, venous blood activities were consistent with arterial activity, presumably because of the numerous arteriovenous anastomoses in the palm. Optimal times for venous blood sampling, with and without palm heating, were determined by error analysis to be 15 and 20 min, respectively, after IMP infusion.

CONCLUSION

Venous blood sampling from the dorsal hand can be substituted for arterial blood sampling in IMP-CBF studies.

Existing variations on the gene structure of hepatitis E virus strains from some regions of China

The isolation and identification of the 87A strain of hepatitis E virus (HEV) by means of cell culture have been described previously. This paper reports the nucleotide sequence of a portion of this HEV strain. The RNA extracted from the supernatants of the different passages of the 87A strain cultured in the A549 cell line was reverse-transcribed (RT) to cDNA, and then the polymerase chain reaction (PCR) amplification was carried out using the primers of HEV ET1.1 region. The PCR products from 1) the supernatant of the infected cells at the fourth passage, 2) the virus concentrated by polyethylene glycol (PEG) precipitation at the tenth passage, and 3) the virus purified by a sucrose gradient at the tenth passage were sequenced. In addition, three other PCR products obtained from sera of acute hepatitis E patients in Beijing (B-9) and Guangzhou (G-9 and G-20) were also sequenced. The nucleotide sequences of the above four strains of HEV (located in the genome from positions 4545-4754) were compared to those of some reported HEV strains. The nucleotide sequences of the B-9 strain and the 87A strain were similar to the Burmese strain and may belong to the same branch of HEV. The nucleotide sequences of the G-9 strain and the G-20 strain were a novel and unique branch. The Chinese HEV strains are multiplex and variable in gene structure.

Bilateral common iliac artery aneurysms secondary to fibromuscular dysplasia accompanied with a coronary aneurysm. A case report

Fibromuscular dysplasia (FMD) is found in various arteries but the common iliac arteries and the coronary arteries are seldom involved. A 49-year-old woman was referred to our hospital with a pulsatile mass in her right lower quadrant. She had subdural hemorrhage in a postpartum state at the age of 27. After admission angiography diagnosed the bilateral iliac artery aneurysms and coronary angiography revealed a coronary artery aneurysm, the size of which was 12 mm x 19 mm in the region of the left main trunk. The bilateral iliac artery aneurysms were resected and Y-shaped vascular prosthesis was replaced. Microscopic sections of the aneurysm showed remarkable decrease of elastic fibers and thinning of the media, but no increase occurred in the smooth muscle. Histopathological diagnosis was FMD (periarterial fibroplasia). To our knowledge, no patient with a iliac arterial aneurysm caused by FMD has been reported and only a few cases with coronary arterial FMD have been described. This is the first report of iliac arterial aneurysm due to FMD. Since this case has multiple aneurysms, a long-term follow-up is definitely required, especially focusing on the coronary aneurysm.

Hepatitis E virus (87A strain) propagated in A549 cells

A strain of hepatitis E virus (HEV), the 87A strain isolated in 2BS cells from the feces of a patient with hepatitis E, has been reported previously. In this study, the 87A strain was propagated in A549 cells, and the marked cytopathic effect (CPE) appeared in the infected monolayer cells. The size of this virus is about 30 nm in diameter. Furthermore, HEV-RNA from the supernatants of the virus of different passages was detected by polymerase chain reaction (PCR) amplification using ET1.1 HEV primers. A band of HEV for 239 bp from PCR products was revealed by electrophoresis. PCR products of the fourth passage were sequenced. These results show that the 87A virus replicates in the A549 cell line.

Cerebral metabolism of oxygen and glucose in a patient with MELAS syndrome

We studied cerebral oxygen and glucose metabolism as well as cerebral blood flow using positron emission tomography (PET) in a case with MELAS showing dementia, diabetes mellitus, ataxia and lactic acidosis without any signs of stroke. This case, confirmed to have a point mutation at position 3243 in the transfer RNA gene of mitochondrial DNA, developed a stroke-like episode 8 months after the PET study. Uncoupling was observed between cerebral oxygen metabolism and cerebral blood flow with reduced fractional oxygen extraction ratio, indicating "hyperemia", not ischemia. The "hyperemia" may be closely related to the malfunction of mitochondria in aerobic energy production. A drastic decrease in cerebral oxygen metabolism (CMRO2) was found globally in contrast to preserved cerebral glucose metabolism (CMRglu), resulting in a remarkable decrease in the metabolic ratio (CMRO2/CMRglu). The dissociation between cerebral glucose and oxygen metabolism may be characteristic of MELAS.

Cloning of a cDNA encoding a 190-kDa insulin receptor substrate-1-like protein of simian COS cells

Major insulin signals such as stimulation of glucose uptake and DNA synthesis and modification of hexose metabolism are mediated by the tyrosine-phosphorylated insulin receptor substrate-1 (IRS-1; pp180) in many species of cells. We cloned cDNA encoding a 190-kDa IRS-1-like protein (pp190) in simian COS cells and which is slightly larger than IRS-1 (pp180) of human, rat, and mouse cells. The deduced amino acid sequence of COS pp190 consisted of 1251 amino acids and was 96.4%, 87.9% and 88.7% identical to human, mouse and rat IRS-1. The COS pp190 bound to SH2 (src-homology 2) domains of p85, Grb2/Ash, and SH-PTP2, as did IRS-1. In IRS-1-knockout mice, insulin signals are thought to be mediated by IRS-2 (pp190), which is an alternative signaling molecule and is slightly larger than IRS-1. However, the COS pp190 may be a simian homologue of IRS-1, but not of IRS-2. The results of Southern blotting suggested the possibility that Chinese hamster ovary (CHO) cells have not only the IRS-1 gene but also a gene related to the COS pp190.

Factors related to stress in patients with non-insulin-dependent diabetes mellitus

Stress was assessed using State-Trait Anxiety Inventory scores in 40 non-insulin-dependent diabetes mellitus (NIDDM) patients, and the results were compared with those for 40 sex- and age-matched healthy controls. Fludiazepam was administered to the patients for 12 weeks and stress was reassessed. The Manifest Anxiety Scale score correlated with Trait (r = 0.548, P < 0.0001) and State (r = 0.474, P = 0.0001) scores, validating the latter as measurements of stress. Both Trait (43.4 vs 35.8, P < 0.001) and State (41.6 vs 33.8, P < 0.001) scores were significantly higher in NIDDM patients than in healthy controls. Administration of an anxiolytic, fludiazepam (0.25 mg, three times daily, orally) for 12 weeks lowered Trait score (43.5 to 36.9, P < 0.0001), State score (41.6 to 35.8, P < 0.0002), glycosylated haemoglobin (8.4 to 7.3%, P < 0.0001), systolic blood pressure (151.2 to 143.4 mmHg, P < 0.0017) and diastolic blood pressure (84.2 to 77.7 mmHg, P < 0.0018). Multiple regression analysis revealed that the significant explanatory variables for the change in State score during anxiolytic administration were the changes in total cholesterol, high-density lipoprotein cholesterol, triglycerides, apolipoprotein B:A1 and glycosylated haemoglobin (R2 = 0.3224, P < 0.0022). The results indicate that stress is detected at a higher frequency in patients with NIDDM than in healthy controls, and that blood glucose and lipid metabolic factors are significant explanatory variables for this stress. This stress is correlated with glucose metabolism and blood pressure and, moreover, these factors could all be proved concomitantly by the administration of an anxiolytic.

Error analysis of autoradiography method for measurement of cerebral blood flow by 123I-IMP brain SPECT: a comparison study with table look-up method and microsphere model method

N-isopropyl-p-[123I]iodoamphetamine (IMP) has been commonly used as a cerebral blood flow tracer, but, significant clearance of IMP from the brain to the blood causes underestimation of cerebral blood flow (CBF) as compared with true CBF when the conventional microsphere model method is applied. Previously, we reported an "Autoradiography method" (ARG method) for measuring CBF by using IMP in which this clearance effect was corrected. This method was based on a two-compartment model (influx: K1, efflux: k2, K1/k2 = distribution volume of IMP (Vd)), the K1 (corresponding to CBF) being obtained form the table which showed a correlation between CBF and the brain counts of SPECT scan with a constant Vd value. Arterial input data used were obtained by one point blood sampling 10 min after IMP infusion against the standard input function. In the present study, the ARG method was compared with the table look-up method (TLU method) and the conventional microsphere model method (MS method) for 30 subjects. When the Vd value in the ARG method was assumed to be 50 ml/ml, CBF values obtained by the ARG method were correlated well with those obtained by the TLU method (Y = 1.04X-2.5; X: TLU, Y: ARG r = 0.97) and those obtained by the MS method (Y = 0.82X + 12.1; X: ARG, Y: MS, r = 0.84). But, when the Vd value was assumed to be more or less than 50 ml/ml, ARG method CBF were under- or overestimated compared with the TLU method. This indicated that the ARG method could be a reliable method for CBF measurement if the Vd was determined properly. CBF values obtained by the MS method were actually 13.2% higher than those obtained by the ARG method against previous studies. As reasons for this, errors in the effects of gray-white matter mixture in the ARG method and in estimation of the SPECT brain counts at 8 min in the MS method were considered.

[Analysis of infiltrating lymphocytes in choroidal melanoma]

We performed immunohistochemistry on tumor infiltrating lymphocytes (TILs) in a 78-year-old man with choroidal malignant melanoma. Cell suspensions of TILs from fresh specimens and peripheral blood lymphocytes (PBLs) were stained with anti-CD3, anti-CD4, anti-CD8, anti-CD29, anti-CD45RA, and anti-human leukocyte antigen (HLA)-DR monoclonal antibodies and analyzed using three-color flow cytometry. In light microscopy, the number of infiltrating lymphocytes around the tumor was very small. Immunohistochemically, T lymphocytes were more numerous than B lymphocytes. Flow cytometric analysis showed that CD8+ cells were more numerous than CD4+ cells in CD3+ cells in TILs, and most of these cells also expressed HLA-DR antigen. CD29+ (memory) cells were increased and CD45RA+ (naive) cells were decreased in CD4+ cells in TILs as compared with PBLs. We concluded that the increase in the percentage of activated memory T lymphocytes and the decrease of naive T lymphocytes may reflect a localized antigen-specific immunological response in choroidal malignant melanoma.

Mechanism of bradykinin-induced cyclic GMP accumulation in bovine tracheal smooth muscle

Bradykinin (10(-8) - 10(-5) M) caused a concentration-dependent increase in cyclic GMP (cGMP) production in bovine tracheal smooth muscle in the absence of epithelium. The effect was calcium-dependent and was inhibited by pyrogallol (10 microM) and methylene blue (10 microM). The inhibition of pyrogallol was reversed by superoxide dismutase (100 U/ml). Nitric oxide (NO) synthase inhibitors, NG-methyl-L-arginine (10-100 microM) and NG-nitro-L-arginine (10-100 microM) reduced cGMP accumulation induced by bradykinin in a concentration-dependent fashion, and the inhibition was reversed by L-arginine. Immunohistochemistry with a specific antibody against neuronal NO synthase from rat cerebellum showed positive staining localized in some nerve fibers. Bradykinin-induced cGMP accumulation appears to be related to the release of NO, part of which is probably synthesized in nonadrenergic noncholinergic nerve in bovine trachea.

Can alpha-glucosidase inhibitors reduce the insulin dosage administered to patients with non-insulin-dependent diabetes mellitus?

For 10 patients (three women and seven men) with noninsulin-dependent diabetes mellitus, who had been given insulin (22.6 +/- 19.6 U/day) and had frequently shown hypoglycaemia, the insulin dose was slightly reduced and the administration of an alpha-glucosidase inhibitor was simultaneously started. Hypoglycaemic symptoms disappeared immediately and completely, and sugar metabolism immediately before the withdrawal of treatment was not aggravated: the glycosylated haemoglobin level was unchanged and the post-prandial blood glucose level was increased though not significantly. The results of the present study indicate that the combined used of an alpha-glucosidase inhibitor with a reduced insulin dose improves the quality of life of patients and may improve hyperinsulinaemia.

Is there a correlation between cardiac sympathetic neuropathy or diabetic somatic neuropathy and glycosylated haemoglobin or blood pressure in patients with non-insulin-dependent diabetes mellitus?

The possibility that glycosylated haemoglobin levels and/or blood pressure might correlate with cardiac sympathetic neuropathy and/or diabetic somatic neuropathy was investigated in patients with non-insulin-dependent diabetes mellitus. Sympathetic nerve function was quantified by analysis of [123I]metaiodobenzylguanidine accumulation in the cardiac muscle. Somatic nerve function was assessed by measuring the motor nerve conduction velocities of the peroneal and tibial nerves, and the sensory nerve conduction velocity of the sural nerve. None of the parameters of cardiac sympathetic neuropathy or diabetic somatic neuropathy showed any correlation with blood pressure, nor was there any evidence of a correlation between cardiac sympathetic neuropathy and glycosylated haemoglobin levels; there was, however, a significant correlation between diabetic somatic neuropathy (as indicated by tibial nerve conduction velocity) and glycosylated haemoglobin levels. The results are consistent with the view that different mechanisms are involved in the two types of neuropathies.

Effect of alpha-glucosidase inhibitor in combination with sulphonylurea compounds on lipid profile in patients with non-insulin-dependent diabetes mellitus

The effects of administration of an alpha-glucosidase inhibitor and a sulphonylurea compound on lipid profile were investigated in patients with non-insulin-dependent diabetes mellitus, (NIDDM) previously treated with sulphonylurea compounds alone, but in whom metabolic control was inadequate. A group of patients (n = 10) were treated with the alpha-glucosidase inhibitor at a dose of 0.2 mg, three times daily, for 4 weeks. Treatment significantly reduced the post-prandial glucose level and the serum total cholesterol level. In addition, there were non-significant reductions in the triglyceride and very low density lipoprotein levels. These preliminary results suggest that administration of alpha-glucosidase inhibitors might improve the lipid profile of patients with NIDDM.

In vitro dissolution tests corresponding to the in vivo dissolution of clarithromycin tablets in the stomach and intestine

The correlation between in vivo and in vitro dissolution of clarithromycin (CAM) tablets was examined. In vivo dissolution rate constants in the stomach and the intestine were obtained from analysis of the urinary excretion data of CAM following oral administration to humans in the fasting or postprandial state using a pharmacokinetic model including gastrointestinal transit. In the present study, the flow-through cell method with moderate agitation was used, as the in vitro dissolution test related to the in vivo dissolution rate constants. Both the effects of pH of the dissolution medium and the volumetric solvent flow rate on the dissolution rate in the flow-through cell method were examined. The pH of the dissolution medium and the flow rate were related to the in vitro dissolution rate. Therefore, the conditions of the flow-through cell method in correlation with the in vivo dissolution rates in the stomach and intestine were determined by controlling the flow rate at pH 3.0 and 6.8 dissolution medium. The urinary excretion of CAM, simulated by substituting the in vitro dissolution rate constants into the equation, were consistent with the in vivo data. The in vitro tests corresponding to the in vivo dissolution in the stomach and intestine following a single oral administration in the fasting or postprandial state for a CAM tablet were established.

[Regional cerebral glucose metabolism associated with ataxic gait--an FDG-PET activation study in patients with olivopontocerebellar atrophy]

We studied changes in regional cerebral glucose metabolism during bipedal gait in 7 patients with olivopontocerebellar atrophy (OPCA) and 7 control subjects without neurological disease. All OPCA patients in this study were able to walk on the treadmill without a support or handrails. We used 18F-2-fluoro-2-deoxy-D-glucose (18F-FDG) and positron emission tomography (PET) to evaluate glucose metabolism under two different conditions; 30 minutes' treadmill walking, and supine resting. The two sets of PET images were three-dimensionally registered to the magnetic resonance image (MRI) in each subject. Then, the PET images were normalized by the global value. Regions of interest (ROIs) were drawn on the cerebellar vermis, cerebellar hemispheres, pons, and thalamus, and FDG uptake was obtained to calculate the activation ratio (= [FDG uptake under walking]/[FDG uptake under resting]) for each region. We used unpaired t-test for statistical analysis to compare the OPCA patients and the normal control subjects. Normalized resting FDG uptake had no significant difference between control subjects and OPCA patients in any region. Activation ratio of OPCA patients was significantly decreased in the cerebellar vermis compared with the control subjects. In the control subjects, FDG uptake had little difference between resting and walking in the cerebellar hemisphere, pons and thalamus. On the other hand, the FDG uptake of OPCA patients was moderately increased by walking in these regions. In the cerebellar vermis, in spite of no significant difference between the normals and the patients during resting, the activation ratio in OPCA patients was significantly decreased. We speculate that the reduction of activation ratio in the cerebellar vermis reflects the dysfunction caused by degeneration. The result suggests that the PET activation study can demonstrate cerebellar dysfunction in the early phase of OPCA, in which other neuro-imaging methods cannot detect the tissue atrophy, hypometabolism or hypoperfusion in the resting state. In the cerebellar hemisphere, pons and thalamus, the activation ratio was nearly equal to one in control subjects, while it was larger in OPCA patients. We speculate that the instability during the ataxic gait increases the inputs from the vestibular, somatosensory and visual systems to these regions and outputs from these regions to the other neural systems. In conclusion, PET activation study is a useful and noninvasive technique for investigating the brain function associated with human gait.

Insulin secretion levels necessary for efficacy of an alpha-glucosidase inhibitor on glucose metabolism in patients with non-insulin-dependent diabetes mellitus

Twenty patients with non-insulin-dependent diabetes mellitus whose glucose metabolism was unsatisfactory, even though they were receiving appropriate dietary therapy, were treated with an alpha-glucosidase inhibitor (0.6 mg/day) for 12 weeks. The connecting peptide immunoreactivity value (selected as the evaluation criterion of post-prandial endogenous insulin secretion) was compared in patients with and without improved glycosylated haemoglobin levels. A significant difference was found between the connecting peptide immunoreactivity value of the group with improved glycosylated haemoglobin levels (5.0 +/- 1.0 ng/ml) and that in the group without the improvement (2.7 +/- 0.9 ng/ml).

Case report: thyrotropin-releasing hormone-induced myoclonus and tremor in a patient with Hashimoto's encephalopathy

The authors investigated the possibility of a thyrotropin-releasing hormone-related mechanism in a 43-year-old Japanese woman with Hashimoto's encephalopathy who experienced three relapses closely associated with the menstrual cycle. Her symptoms began at ovulation, worsened during the luteal phase, and improved during the menstruation phase. No abnormalities were found by brain magnetic resonance imaging and cerebral angiography. Intravenous administration of thyrotropin-releasing hormone induced symptoms of myoclonus and tremor similar to those observed during an exacerbation. The intensity and duration of involuntary movements induced by thyrotropin-releasing hormone were dose-dependent. The patient's symptoms were controlled effectively by thyroxine replacement therapy. On the basis of these findings, thyrotropin-releasing hormone may have an important role in Hashimoto's encephalopathy.

Can alpha-glucosidase inhibitors reduce the dosage of sulphonylurea compounds needed by patients with non-insulin-dependent diabetes mellitus?

The effects of treatment with an alpha-glucosidase inhibitor and a reduced dose of sulphonylurea were investigated in patients with non-insulin-dependent diabetes mellitus who had previously been treated with sulphonylurea compounds but who were hypoglycaemic at times. Treatment with a daily dose of 0.6 mg alpha-glucosidase inhibitor and a reduced dose of the previously used sulphonylurea compound for 4 weeks did not significantly affect the glycosylated haemoglobin level. The post-prandial blood-glucose concentration of the patients was unchanged after treatment compared with its value immediately before treatment but differed significantly compared with the value 4 weeks before treatment (P < 0.03); it was considered likely that this change was due to a seasonal increase in calorie intake at the end of the treatment period. Symptoms related to hypoglycaemia disappeared in all of the treated patients.

[Influence on glycemic control of improved diabetic gastroparesis by long-term cisapride therapy]

To investigate the effect on glycemic control of improving diabetic gastroparesis, we evaluated symptoms (scored), gastric motor functions (solid and liquid gastric emptying studies and electrogastrography), and glycemic control in 11 patients with diabetic gastroparesis (5 men, 6 women, 50.4 +/- 4.5 years old) before and after treatment with cisapride (15 mg/day p.o., 12 weeks). None of the patients had organic abnormalities on gastrointestinal endoscopy. The dysmotility symptom score (maximum: 18) on cisapride significantly improved from 13.1 to 4.0 (p < 0.01). Retention rates at 15 and 80 minutes after ingestion improved in a solid-food gastric emptying study using a test meal of instant noodles labeled with 37 MBq (1 mCi) technetium-99m (both p < 0.05). Liquid gastric emptying, evaluated using a sulfamethizole technique, also improved but not significantly. Electrogastrography revealed no significant changes after treatment, but the postprandial rate of normal frequency waves tended to increase. Glycemic control was assessed based on HbA1C, fructosamine and M value. There were no significant changes in glycemic control after treatment with cisapride. We conclude that long-term administration of cisapride reduced dysmotility symptoms and improved solid and liquid gastric emptying without adversely affecting glycemic control.

Determination of KA values by controlled receptor expression in Xenopus oocytes

1. In the present study we estimated the KA value of endothelin-1 (ET-1) for ETA-receptors by a new method in which the level of expression of ETA-receptors in Xenopus oocytes was altered in a controlled way. 2. Kvl.2 (a delayed rectifier type K channel) c RNA at the fixed concentration of 0.2 micro g micro l(-1) was mixed with ETA-receptor cRNA at various concentration ratios (10(-3)-3). Oocytes were examined 2-4 days after the injection of the cRNA mixtures. 3. In these oocytes, ET-1 suppressed the amplitude of Kvl.2 current in a dose-dependent manner in the range of 0.1-100 nM; the maximum inhibition produced by ET-1 was larger and the EC50 value for the inhibition by ET-1 was smaller as the mixture ratio was increased. Double-reciprocal plots of equiactive concentrations of ET-1 in 1/1- and 1/30-injected oocytes yielded a KA for ET-1 of 7.4 nM. The number of ETA-receptors in 1/30-injected oocytes was 13% of that in 1/1-injected oocytes, whereas the inhibition of the current in 1/30-injected oocytes was about 60% of that in 1/1-injected oocytes. This suggests the presence of spare receptors of ETA in the latter. 4. A saturation binding experiment estimated a KD value of 0.1 nM for ET-1 at ETA-receptors and the number of ETA-receptors in 1/30-injected oocytes was 23% of that in 1/1-injected ones. This value was not significantly different from that estimated by the above new method. However, there was a discrepancy between KA and KD, which could be due to factors unique to the expression system employed in the present study.

The voltage-dependent K+ channel (Kv1.5) cloned from rabbit heart and facilitation of inactivation of the delayed rectifier current by the rat beta subunit

We have isolated a cDNA coding for a delayed rectifier K+ channel (RBKV1.5) from rabbit heart. The amino acid sequence of RBKV1.5 displays a homology to that of other K+ channels of Kv1.5 class. Overall amino acid identity between RBKV1.5 channel and Kv1.5 channel of other species is about 85%. RNA blot analysis revealed the expression of the primary transcript in various rabbit tissues, at the highest level in both the atrium and ventricle. When expressed in Xenopus oocytes, RBKV1.5 current showed a delayed rectifier type characteristics, which was converted to rapidly inactivating currents upon coexpression with a beta subunit.