Ginkgo biloba leaf extract (EGb 761®) and its specific acylated flavonol constituents increase dopamine and acetylcholine levels in the rat medial prefrontal cortex: possible implications for the cognitive enhancing properties of EGb 761®.

Experimental and clinical data suggest that the Ginkgo biloba standardized extract EGb 761® exerts beneficial effects in conditions which are associated with impaired cognitive function. However, the neurochemical correlates of these memory enhancing effects are not yet fully clarified. The aim of this study was to examine the effect of repeated oral administration of EGb 761® and some of its characteristic constituents on extracellular levels of dopamine (DA), noradrenaline (NA), serotonin (5-HT), acetylcholine (ACh) and the metabolites 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) in the medial prefrontal cortex (mPFC) of awake rats by use of in vivo microdialysis technique. Subacute (14 days, once daily), but not acute, oral treatment with EGb 761® (100 and 300 mg/kg) or the flavonoid fraction, which represents about 24% of the whole extract caused a significant and dose-dependent increase in extracellular DA levels in the mPFC. Repeated administration of EGb 761® also caused a modest but significant increase in the NA levels, whereas the concentrations of 5-HT and those of the metabolites DOPAC, HVA and 5-HIAA were not affected. The same treatment regimen was used in a subsequent study with the aim of investigating the effects of two Ginkgo-specific acylated flavonols, 3-O-(2''-O-(6'''-O-(p-hydroxy-trans-cinnamoyl)-ß-D-glucosyl)-α-L-rhamnosyl)quercetin (Q-ag) and 3-O-(2''-O-(6'''-O-(p-hydroxy-trans-cinnamoyl)-ß-D-glucosyl)-α-L-rhamnosyl)kaempferol (K-ag). Both compounds together represent about 4.5% of the whole extract. Repeated oral treatment with Q-ag (10 mg/kg) for 14 days caused a significant increase in extracellular DA levels of 159% and extracellular acetylcholine (ACh) levels of 151% compared to controls. Similarly, administration of K-ag (10 mg/kg) induced a significant rise of DA levels to 142% and ACh levels to 165% of controls, whereas treatment with isorhamnetin, an O-methylated aglycon component of EGb 761® flavonol glycosides had no effect. None of the tested flavonoids had a significant effect on extracellular DOPAC and HVA levels. The present findings provide evidence that the subacute treatment with EGb 761® and its flavonol constituents increases DA and ACh release in the rat mPFC, and suggest that the two Ginkgo-specific acylated flavonol glycosides Q-ag and K-ag are active constituents contributing to these effects. As seen for isorhamnetin, the effect on neurotransmitter levels seems not to be a general effect of flavonols but rather to be a specific action of acylated flavonol glycosides which are present in EGb 761®. The direct involvement of these two flavonol derivatives in the increase of dopaminergic and cholinergic neurotransmission in the prefrontal cortex may be one of the underlying mechanisms behind the reported effects of EGb 761® on the improvement of cognitive function.

Determination of histamine in microdialysis samples from Guinea pig skin by high-performance liquid chromatography with fluorescence detection.

AIM: To develop a sensitive and selective liquid-chromatographic method for the determination of histamine in microdialysis samples from guinea pig skin following allergenic provocation. METHODS: The novel fluorescence derivatization method is based on an intramolecular excimer-forming reaction between 2 amino moieties of histamine and 2 molecules of 4-(1-pyrene)butanoyl chloride (PBC) yielding the corresponding dipyrene-labeled derivative. RESULTS: The PBC derivative of histamine was separated within 20 min, and the detection limit (signal-to-noise ratio = 3) of histamine was 0.6 fmol/20 µl volume injected. The basal extracellular levels of histamine in guinea pig skin microdialysates were 20.6 ± 1.7 fmol/10 µl. Subcutaneous administration of histamine liberator compound 48/80 (3 mg/kg) increased the extracellular histamine levels in the skin dialysates by about 860%, whereas ovalbumin challenge (2 mg/kg i.v.) in the sensitized guinea pigs increased the extracellular histamine levels by about 3,030%. CONCLUSION: The novel technique for histamine determination in microdialysis samples from the guinea pig skin may be utilized in preclinical research of antihistaminergic drugs and evaluation of allergenic properties of various dermal preparations such as transdermal drug delivery systems.

Diffusion and clearance of superparamagnetic iron oxide nanoparticles infused into the rat striatum studied by MRI and histochemical techniques.

The purpose of the present study was to investigate, by MRI and histochemical techniques, the diffusion and clearance abilities of superparamagnetic iron oxide nanoparticles (SPION) coated with dextran (Dextran-SPION) and gold (Au-SPION) following their local infusions into the rat brain. In separate groups of anesthetized rats, the Dextran-SPION and Au-SPION were infused at concentrations of 0.01, 0.1, 1 and 5 µg Fe/0.5 µl and at the flow rate of 0.5 µl min(-1) into the left and right striata, respectively. Repetitive T2-weighted spin-echo MRI scans were performed at time intervals of 1, 6, 12, 24, 48, 72 h, and one, two and eight weeks after inoculation. Following infusion of Dextran-SPION (0.1 µg and 1 µg Fe), the maximal distribution volume was observed at about 12-24 h after inoculation and two weeks later the Fe signals were undetectable for the lower dose. On the other hand, Au-SPION remained tightly localized in the closest vicinity of the infusion site as revealed by unchanged MRI signal intensities and strong histochemical staining of Fe(2+) and Fe(3+) ions in the corresponding brain slices. Immunohistochemical staining of astrocytic and microglial reactions revealed that there were no marked differences in GFAP, VIM or OX-42 labeling observed between the nanoparticle types, however the astrocytic reaction was more pronounced in rats receiving nanoparticles compared to the control (aCSF-infused) rats. In conclusion, the present data demonstrate that the viral-sized Dextran-SPION were able to diffuse freely through the interstitial space of the brain being progressively cleared out from the infusion site within two weeks. Thus, Dextran-SPION could be beneficially used in MRI-guided diagnostic applications such as in experimental oncology or as labels and carriers for targeted drug delivery, whereas Au-SPION could be used for labeling and tracking the transplanted stem cells in experimental MRI.

Diabetes and cardiovascular disease in a prospective population survey in Japan: The Hisayama Study.

To elucidate the effect of glucose intolerance on cardiovascular disease in the current Japanese population, we performed a 75-g oral glucose tolerance test in 2,427 Hisayama residents aged 40-79 years in 1988, who were free from a previous history of stroke or myocardial infarction, and followed them prospectively for 5 years. The prevalence of diabetes (NIDDM) among men was 13% and that of impaired glucose tolerance (IGT) was 20%; the corresponding values for women were 9 and 19%, respectively. The age- and sex-adjusted incidence of cerebral infarction (6.5 per 1,000 person-years, P < 0.01) and coronary heart disease (5.0 per 1,000 person-years, P < 0.05) was significantly higher in subjects with NIDDM than in those with normal glucose tolerance (1.9 and 1.6 per 1,000 person-years, respectively). In addition, subjects with IGT and NIDDM had a higher risk of cardiovascular disease including stroke and coronary heart disease than did those with normal glucose tolerance after adjustment for age and sex, namely the relative risk for IGT was 1.9 (95% CI 1.2-3.2), and the relative risk for NIDDM was 3.0 (95% CI 1.8-5.2). These associations remained significant even after controlling for six other risk factors including hypertension in multivariate analysis. Our data suggest that NIDDM is a significant risk factor for both cerebral infarction and coronary heart disease and also that IGT itself is a risk factor for cardiovascular disease in the general Japanese population today.

Comparison of a digital flat-panel versus screen-film, photofluorography and storage-phosphor systems by detection of simulated lung adenocarcinoma lesions using hard copy images.

The purpose of this study was to compare hard copy images from a flat-panel detector digital radiography system with conventional radiography, photofluorographic radiography and storage phosphor radiography for the detection of simulated lung adenocarcinoma lesions and also for radiation dose. To test the diagnostic performance of these four systems, the authors used 15 types of lung adenocarcinoma phantom according to Noguchi's classification and an anthropomorphic chest phantom. The visual evaluation of tumour detectability by four radiologists and two general thoracic surgeons was examined with a five-level confidence scale. Lung doses were measured with glass dosemeters for the chest radiology systems under the conditions used by each hospital and centre. Our results indicated that flat-panel detector digital radiography and storage phosphor radiography are not necessarily superior to conventional radiography and photofluorographic radiography for detecting lung adenocarcinomas when only hard copy images are used, and this suggests a need to carefully optimize chest radiography.

Incidence and risk factors of vascular dementia and Alzheimer's disease in a defined elderly Japanese population: the Hisayama Study.

We followed 828 nondemented residents of Hisayama Town, Kyushu, Japan, aged 65 years or older (88.3% of the elderly population) for 7 years starting in 1985 in order to determine the type-specific incidence of dementia and its risk factors in the general Japanese population. Only two subjects were lost to the follow-up, during which period 103 subjects developed dementia. Morphologic examination of the brains of 89 subjects (86.4%) was made by autopsy or CT. We made the initial diagnosis of dementia based on the DSM-III-R criteria, with the diagnoses of vascular dementia (VD) being based on the NINDS-AIREN criteria and Alzheimer's disease (AD) on the NINCDS-ADRDA criteria. The incidence of VD and AD increased with age for both sexes. The age-adjusted total incidence (per 1,000 person-years) of dementia was 19.3 for men and 20.9 for women. The corresponding rates for VD were 12.2 for men and 9.0 for women, and for AD, 5.1 for men and 10.9 for women. Among the VD subjects whose brain morphology we examined, the most frequent type of stroke was multiple lacunar infarcts (42%), but half these subjects lacked a stroke episode in their histories. Multivariate analysis showed that age, prior stroke episodes, systolic blood pressure, and alcohol consumption were significant independent risk factors for the occurrence of VD. In contrast, age and a low score on Hasegawa's dementia scale were significant risk factors for AD, and physical activity was a significant preventive factor for AD.(ABSTRACT TRUNCATED AT 250 WORDS)

Activation of 5-HT(1A) autoreceptors enhances the inhibitory effect of galanin on hippocampal 5-HT release in vivo.

The microdialysis technique was used to examine interactions between 5-HT(1A) and galanin receptors in the dorsal raphe nucleus (DRN), by measuring the extracellular levels of 5-HT in the ventral hippocampus of awake rats. The rats were pretreated with the 5-HT(1A) receptor agonist (R,S)-8-OH-DPAT (0.3 mg/kg, s.c.) or saline. 8-OH-DPAT caused a time-dependent reduction of basal 5-HT levels down to 43-48% at 40 min while at 140 min, the hippocampal 5-HT had returned to control values. At that time point, the rats received a second injection of 8-OH-DPAT or galanin (0.15, 0.5 and 1.5 nmol/0.5 microl) infused into the lateral ventricle. The second injection of 8-OH-DPAT caused a significantly smaller reduction of hippocampal 5-HT levels. In contrast, galanin at all three doses in the 8-OH-DPAT-pretreated groups, was significantly more potent in reducing 5-HT levels (maximal reduction to 74%, 52% and 49%, respectively) than it was in saline-pretreated rats (maximal reduction to 96%, 85% and 69%, respectively). The inhibitory effect of galanin (1.5 nmol) on extracellular 5-HT levels in the rat hippocampus was significantly attenuated by co-administration of the 5-HT(1A) receptor antagonists WAY-100635 (0.3 and 0.6 mg/kg s.c.) and, to a lesser extent, with pindolol (20 mg/kg s.c.). These data provide direct in vivo evidence of agonistic 5-HT(1A)-galanin receptor interaction at the presynaptic level. Furthermore, the findings indicate that a down-regulation of the somato-dendritic 5-HT(1A) autoreceptors, following their stimulation with 8-OH-DPAT and possibly also indirectly with 5-HT reuptake inhibitors, may be compensated by a subsequent 'sensitization' of the inhibitory galanin receptors in the DRN. Thus, the enhanced galanin receptor-mediated inhibition of 5-HT neurotransmission may contribute to the pathophysiology of depression or to the reduced and delayed efficacy of antidepressant therapies.

Hyperinsulinaemia and blood pressure in a general Japanese population: the Hisayama Study.

OBJECTIVES: To study the relationship between serum insulin and blood pressure, as well as the prevalence of hypertension according to the insulin level in a general Japanese population. DESIGN: In 1988 a cross-sectional community survey was conducted among Hisayama residents aged 40-79 years. METHODS: A total of 1073 males and 1407 females (72.5 and 80.5% of the total population, respectively) underwent comprehensive investigation, including a 75-g oral glucose-tolerance test. Fasting and 2-h serum insulin levels were measured by radioimmunoassay. RESULTS: The sum of the fasting and 2-h postloading insulin levels was significantly correlated with the systolic blood pressure (SBP; r = 0.18 and 0.26 for males and females, respectively) and the diastolic blood pressure (DBP; r = 0.24 and 0.19, respectively) in the subjects not receiving antihypertensive drugs. In multiple regression analysis the correlation with blood pressure remained significant in both sexes even after controlling for age, body mass index, alcohol intake, smoking, a family history of hypertension, serum total cholesterol and fasting plasma glucose. The age- and sex-adjusted prevalence of hypertension (SBP > or = 160 mmHg or DBP > or = 95 mmHg, or both, or receiving drug treatment) increased significantly with an increase in the sum of fasting and 2-h postload insulin levels in both the non-obese subjects (body mass index < 25 kg/m2) and the obese subjects (body mass index > or = 25 kg/m2). Multiple logistic regression showed that the sum of fasting and 2-h postload insulin levels was a significant factor with an independent relationship to hypertension, even after taking the other risk factors into account. CONCLUSION: The present study suggests that hyperinsulinaemia is related to hypertension in a general Japanese population.

Intraseptal muscarinic ligands and galanin: influence on hippocampal acetylcholine and cognition.

The cholinergic neurons in the septohippocampal projection are implicated in hippocampal functions such as spatial learning and memory. The aim of this study was to examine how septohippocampal cholinergic transmission is modulated by muscarinic inputs and by the neuropeptide galanin, co-localized with acetylcholine (ACh) in septohippocampal cholinergic neurons, and how spatial learning assessed by the Morris water maze test is affected. Muscarinic inputs to the septal area are assumed to be excitatory, whereas galanin is hypothesized to inhibit septohippocampal cholinergic function. To test these hypotheses, compounds were microinjected into the medial septum and hippocampal ACh release was assessed by microdialysis probes in the ventral hippocampus of the rat. Blockade of septal muscarinic transmission by intraseptal scopolamine increased hippocampal ACh release suggesting that septal cholinergic neurons are under tonic inhibition. Stimulation of septal muscarinic receptors by carbachol also increased hippocampal ACh release. Despite this increase, both scopolamine and carbachol tended to impair hippocampus-dependent spatial learning. This finding also suggests a revision of the simplistic notion that an increase in hippocampal ACh may be facilitatory for learning and memory. Galanin infused into the medial septum enhanced hippocampal ACh release and facilitated spatial learning, suggesting that septal galanin, contrary to earlier claims, does not inhibit but excites septohippocampal cholinergic neurons. Galanin receptor stimulation combined with muscarinic blockade in the septal area resulted in an excessive increase of hippocampal ACh release combined with an impairment of spatial learning. This finding suggests that the level of muscarinic activity within the septal area may determine the effects of galanin on hippocampal cognitive functions. In summary, a limited range of cholinergic muscarinic transmission may contribute to optimal hippocampal function, a finding that has important implications for therapeutic approaches in the treatment of disorders of memory function.

Reduced expression of apoptosis-related antigens in thymuses from patients with myasthenia gravis.

Expression of the apoptosis-related antigens, Fas and BM-1, in thymuses from patients with myasthenia gravis (MG) was examined using immunohistochemistry and reverse transcription-polymerase chain reaction (RT-PCR). Fas antigen was markedly decreased in lymphoid follicles in thymuses from patients with MG, but was expressed diffusely in the remaining thymus tissues and in neonatal thymuses. BM-1 antigen was not expressed in the lymphoid follicles or other parts of the thymus. Fas mRNA was also decreased to various degrees in the thymuses from MG patients. Therefore, Fas antigen may play an important role in autoimmune diseases including MG.

Malignant neoplasms in the Japanese community of Hisayama: mortality and changing pattern during a 30-year observation period based on a consecutive autopsy series.

To obtain a relatively true mortality from malignant neoplasms, we studied the frequency of cancers in the different sites and the changing patterns of the frequency and sites over time among residents of the community of Hisayama, where an autopsy-based population survey (autopsy rate, 80%) has been conducted since 191. During the 30-year period from 1962 to 1991, we found 438 malignant neoplasms in 407 cases among 1,250 consecutive autopsies. Stomach cancer was not frequent in type of cancer, with 123 cases (9.8%), followed by lung cancer in 62 (5.0%), colorectal cancer in 42 (3.4%), liver cancer in 37 (3.0%), and pancreatic cancer in 30 (2.4%). We compared the mortality from cancers for both autopsy and nonautopsy cases (the proportional mortality) among three 10-year periods. The proportional mortality from all cancers, as well as for lung, colorectal, and liver cancers, showed an increase in recent years, while stomach and pancreatic cancer showed a decrease. These figures were nearly similar to the mortality statistics for the Japanese population as a whole except for the observed decreasing trend in mortality from pancreatic cancer.

Modulation of acetylcholine and serotonin transmission by galanin. Relationship to spatial and aversive learning.

This paper presents evidence that galanin is a potent in vivo modulator of basal acetylcholine release in the rat brain with qualitatively and quantitatively differential effects in the dorsal and ventral hippocampus. Galanin perfused through the microdialysis probe decreased basal acetylcholine release in the ventral hippocampus, while it enhanced acetylcholine release in the dorsal hippocampus. Galanin (3 nmol/rat) infused into the ventral hippocampus impaired spatial learning acquisition, while it tended to facilitate acquisition when injected into the dorsal hippocampus. These effects appear to be related to activation of GAL-R1 (ventral hippocampus) and GAL-R2 (dorsal hippocampus) receptors, respectively. However, the effects of galanin on acetylcholine release and on spatial learning appear not to be directly related to cholinergic mechanisms, but they may also involve interactions with noradrenaline and/or glutamate transmission. Galanin administered into the lateral ventricle failed to affect acetylcholine release, while this route of administration produced a long-lasting reduction in 5-HT release in the ventral hippocampus, indicating that galanin is a potent inhibitor of mesencephalic 5-HT neurotransmission in vivo. Subsequent studies supported this hypothesis, showing that the effects on 5-HT release in vivo are most likely mediated by a galanin receptor in the dorsal raphe. The implications of these findings are discussed in relation to the role of acetylcholine in cognitive functions in the forebrain and the role of the raphe 5-HT neurons in affective disorders.

Determination of serotonin in microdialysis samples from rat brain by microbore column liquid chromatography with post-column derivatization and fluorescence detection.

The present paper describes a new method for on-line determination of 5-HT in brain microdialysates from awake rats by microbore column liquid chromatography with post-column derivatization and fluorescence detection. The derivatization reagent contained 1 mM benzylamine and 0.5 mM potassium hexacyanoferrate (III), both dissolved in a mixture of acetonitrile and 25 mM borate buffer (pH 11.0) (1:1, v/v). The limit of detection (S/N=3) for 5-HT was 0.5 fmol/20 microl. The samples were injected every 20 min onto a microbore column packed with C18 silica gel. The method exhibits an excellent stability over the periods of at least 12-24 h. The basal levels of 5-HT from 25 awake rats were 7.10+/-1.06 fmol/20 microl in the dorsal hippocampus and 4.64+/-0.91 fmol/20 microl (mean+/-SD) in the striatum. The 5-HT release increased to about 1500% during the perfusion with 100 mM K(+) containing Ringer solution or it was reduced to 60 or 40% during the perfusion with 1 microM tetrodotoxin or calcium free Ringer, respectively. The new method can be used to monitor extracellular 5-HT following acute systemic drug administration.

Microdialysis in freely moving mice: determination of acetylcholine, serotonin and noradrenaline release in galanin transgenic mice.

In the present study, we describe micro-surgical methods for simultaneous implantation of a microdialysis probe and an intraventricular injection cannula via their respective guide cannulas into the mouse brain. Basal and stimulated release of acetylcholine (ACh), serotonin (5-HT) and noradrenaline (NA) was determined in the ventral hippocampus of freely moving mice. NA and 5-HT were determined in one run by a newly developed HPLC method based on precolumn derivatization with benzylamine and fluorescence detection. The mice with a loss-of-function mutation of the galanin gene (KO) and the mice that over-expressed galanin (OE) were studied. No significant differences in basal, potassium-stimulated or scopolamine-induced extracellular ACh levels were observed in 4-month-old wild-type (WT) and KO mice. In the aged, 10-month-old animals, the basal extracellular ACh levels were significantly reduced in both WT and KO groups. Galanin (1 nmol i.c.v.) caused a significant reduction of basal extracellular NA by about 40% in both WT and galanin OE mice, however, in the latter group the effect was delayed by almost 2 h. A 10-min forced swimming stress caused a higher increase in release of NA and 5-HT in the OE group than in the corresponding WT mice. Finally, venlafaxin (10 mg/kg i.p.) increased extracellular NA to 400% of the control values in the CBA mice, but only to 250% in the C57BL mice. It is concluded that galanin may play an important role in the cholinergic mechanisms underlying cognitive disorders. Furthermore, modulation by galanin and by behavioral activation, of NA and 5-HT neurotransmission in galanin over-expressing mice indicates its possible role in the aetiology of mood disorders.

Significance of haemorrhages in central parts of the tongue found in the medicolegal autopsy.

The tongue was examined for the presence of haemorrhages in 264 medicolegal autopsy cases. The tongue was sectioned transversely and examined macroscopically and microscopically. Haemorrhages were found in marginal and/or central parts of the tongue in 104 cases. Among them, 28 cases showed haemorrhages in central parts of the tongue. Those haemorrhages in central parts of the tongue were seen only in cases of severe 'congestive death'. The possibility must therefore be considered of a severe 'asphyxial death', if haemorrhages are found in central parts of the tongue during autopsy.

Ideal anticoagulation for use with a left ventricular assist device.

To establish ideal anticoagulation therapy for use with a left ventricular assist device, a study was done administering various anticoagulants: heparin, argatroban, a prostacyclin analogue combined with a protease inhibitor, or a protease inhibitor alone. Cardiac asisting by LVAD without any anticoagulants results in marked activation of blood coagulation or fibrinolysis. Administration of argatroban, as well as heparin, produces a bleeding tendency. Administration of a protease inhibitor (nafamostat mesilate, FUT-175) as a sole anticoagulant induces activation of the blood coagulation system to some extent, but it is within acceptable limits. Combined administration of a prostacyclin analogue (PG) and FUT-175 is most effective in maintaining balanced blood coagulation and fibrinolysis.

Danger of urokinase as an anticoagulant with left ventricular assist devices.

The sole administration of urokinase causes no initial prolongation of activated partial thromboplastin time (A-PTT), but thereafter produces serious progressive prolongation of A-PTT; it also causes a progressive, severe decrease in fibrinogen levels and alpha 2-plasmin inhibitor activity by depletion. The antithrombogenicity of urokinase is not caused by prevention of blood coagulation system activation by antithrombin effect, but by secondary fibrinolysis by plasmin. Consequently, the administration of urokinase as a sole anticoagulant results in activation of coagulation and fibrinolysis, and, as a result, induces disseminated intravascular coagulation. Therefore, it is concluded that administration of urokinase is an inadequate anticoagulation therapy unless it is combined with other antithrombin agents.

[Primary mediastinal germ cell tumors].

The most frequent site of extragonadal germ cell tumors is the mediastinum. The majority (80%) of mediastinal germ cell tumors are benign mature teratomas, which can be easily removed. Malignant germ cell tumors account for approximately 20% of all cases and are clinically classified into seminoma and non-seminomatous germ cell tumors. Seminomas are radiosensitive and have relatively a good prognosis. Patients with non-seminomatous germ cell tumors had a very poor prognosis, however, the introduction of cis-platinum based chemotherapy has improved the prognosis of patients with these tumors. Three hundred twenty nine cases of malignant mediastinal germ cell tumors have been described in the literature and reports up to 1988 in Japan. The types and cases are following: [table: see text] Multi-drug chemotherapy with cis-platinum has improved the prognosis of patients with embryonal carcinoma and yolk sac tumors, although patients with choriocarcinoma have yet a poor response to the combination chemotherapy. Five year survivors have consisted of 19 patients with seminomas and five patients with non-seminomatous germ cell tumors. Most long survival patients have undergone surgical resection of tumors. The results suggested that the improvement for prognosis requires earlier prognosis and complete surgical removal of tumors associated with chemotherapy combining further effective regimens.

[B cell population and its autoimmune activity in the thymus of patients associated with myasthenia gravis].

Immunohistochemical studies using antibodies to B lymphocyte and to immunoglobulin G bearing cell were carried out for resected thymus-specimens of 10 patients associated with myasthenia gravis. In each case, abundant B cells (L26 positive cell) resided in the follicles and the medulla of thymus, especially, were congregated in the follicles developing germinal center and around Hassall's corpuscles. Amount of B cell population was various among each case regardless of type of myasthenia gravis or age. B cells were greatly increased in the thymus of patients with values of anti-acetylcholine receptor antibody titers over 100 nmol/l. Although numerous B cells were present in the thymus of these patients, IgG bearing cells were extremely rare. In the most cases, B cells lacked IgG expression. From the results, numerous B cells pre-activating autoimmune antibody production were accumulated in the thymus of patients associated with myasthenia gravis.

[Reoperation in patients with thymoma].

For past seven years, reoperations were carried out for six patients with thymoma and myasthenia gravis (MG). Of six patients, five patients were suspected recurrent thymoma and remaining one patient was diagnosed as the residual thymus after thymothymectomy or thymomectomy. Myasthenia gravis has been progressing in five patients after initial operation except for one patient. Two cases of pleural dissemination tumors, one case of local recurrent thymoma and one case of the residual thymus were confirmed by surgery, remaining two patients had no recurrent tumor. As surgical procedure, median sternotomy using for reoperation has a great surgical risk, because left brachiocephalic vein closely adhered to the sternum is apt to be injured. Clinical symptoms of MG were improved in all the patients after reoperation regardless of recurrent tumor.