The structure of graphite oxide: investigation of its surface chemical groups

The structure of graphite oxide (GO) has been systematically studied using various tools such as SEM, TEM, XRD, Fourier transform infrared spectroscopy (FT-IR), X-ray photoemission spectroscopy (XPS), (13)C solid-state NMR, and O K-edge X-ray absorption near edge structure (XANES). The TEM data reveal that GO consists of amorphous and crystalline phases. The XPS data show that some carbon atoms have sp(3) orbitals and others have sp(2) orbitals. The ratio of sp(2) to sp(3) bonded carbon atoms decreases as sample preparation times increase. The (13)C solid-state NMR spectra of GO indicate the existence of -OH and -O- groups for which peaks appear at 60 and 70 ppm, respectively. FT-IR results corroborate these findings. The existence of ketone groups is also implied by FT-IR, which is verified by O K-edge XANES and (13)C solid-state NMR. We propose a new model for GO based on the results; -O-, -OH, and -C=O groups are on the surface.

Single crystals of single-walled carbon nanotubes formed by self-assembly

We report the self-assembly of single crystals of single-walled carbon nanotubes (SWCNTs) using thermolysis of nano-patterned precursors. The synthesis of these perfectly ordered, single crystals of SWCNTs results in extended structures with dimension on the micrometer scale. Each crystal is composed of an ordered array of tubes with identical diameters and chirality, although these properties vary between crystals. The results show that SWCNTs can be produced as a perfect bulk material on the micrometer scale and point toward the synthesis of bulk macroscopic crystalline material.

Growth of Single-Crystalline KNbO3 Nanostructures

This communication reports on the growth of highly uniform KNbO3 nanowires exhibiting a narrow diameter distribution around 60 nm and a length-to-width ratio up to 100. The nanowires were prepared by a hydrothermal route, which enables simple, gram-scale production. A systematic study of the synthesized nanowires in terms of the morphological and chemical characteristics was carried out by varying the temperature-pressure conditions and the composition of the starting mixture. The results indicate that highly uniform single-crystalline nanowires form within a narrow window of the ternary phase diagram of KOH-Nb2O5-H2O.

Treatment of Depression and Effect of Antidepression Treatment on Nutritional Status in Chronic Hemodialysis Patients

BACKGROUND

Depression, which is the most common psychological complication in patients with end-stage renal disease (ESRD), has an impact on the clinical outcome and is associated with malnutrition in chronic hemodialysis patients. This study evaluated the effect of antidepression treatment on nutritional status in depressed chronic hemodialysis patients.

METHODS

Sixty-two ESRD patients who underwent dialysis for more than 6 months were interviewed and completed a Beck Depression Inventory assessment. Thirty-four patients who had scores greater than 18 on the Beck Depression Inventory score and met Diagnostic and Statistical Manual of Mental Disorders, 4th Edition criteria for major depressive disorder were selected to receive paroxetine 10 mg/day and psychotherapy for 8 weeks. The remaining 28 patients were assigned to the control group. Change in the severity of depressive symptoms was ascertained by administering the Hamilton Depression Rating Scale. Nutritional status was evaluated by normalized protein catabolic rate, serum albumin and blood urea nitrogen level.

RESULTS

All patients successfully completed 8 weeks of antidepression treatment. Antidepression treatment decreased the severity of depressive symptoms (Hamilton Depression Rating Scale score: 16.6 +/- 7.0 versus 15.1 +/- 6.6, P < 0.01) and increased normalized protein catabolic rate (1.04 +/- 0.24 versus 1.17 +/- 0.29 g/kg/day, P < 0.05), serum albumin (37.3 +/- 2.0 versus 38.7 +/- 3.2 g/l, P < 0.005), and prehemodialysis blood urea nitrogen level (24.3 +/- 5.6 versus 30.2 +/- 7.9 mmol/L, P < 0.001). In the control group, no change was noted during the study period.

CONCLUSION

This study suggests that antidepressant medication with supportive psychotherapy can successfully treat depression and improve nutritional status in chronic hemodialysis patients with depression.

Observation of antiferromagnetic domains in epitaxial thin films

Antiferromagnetic domains in an epitaxial thin film, LaFeO(3) on SrTiO(3)(100), were observed using a high-spatial-resolution photoelectron emission microscope with contrast generated by the large x-ray magnetic linear dichroism effect at the multiplet-split L edge of Fe. The antiferromagnetic domains are linked to 90 degrees twinned crystallographic regions in the film. The Neel temperature of the thin film is reduced by 70 kelvin relative to the bulk material, and this reduction is attributed to epitaxial strain. These studies open the door for a microscopic understanding of the magnetic coupling across antiferromagnetic-ferromagnetic interfaces.

Vascular leiomyoma of an extremity: MR imaging-pathology correlation

OBJECTIVE

The objective of our study was to analyze MR images of vascular leiomyoma of the extremity and to compare these images with histopathologic findings to determine if a correlation exists.

CONCLUSION

T2-weighted MR images of vascular leiomyoma of an extremity showed a mass with mixed areas that were both hyper- and isointense to skeletal muscle and also revealed a hypointense rim; these images correlate with histopathologic findings of smooth muscle, vessels, fibrous tissue, an intravascular thrombus, and a fibrous capsule.

Abnormal laterality and congenital cardiac anomalies. Relations of visceral and cardiac morphologies in the iv/iv mouse

BACKGROUND

In the management of hearts with deranged laterality, it is essential that the left and right atrial chambers are correctly identified. There are two major approaches, which are based on venous connections or on the morphology of the atrial appendages, and there is no consensus as to which is the most useful. We used the iv/iv mouse mutant, which is known to be pertinent to this problem, to evaluate the relations of cardiac defects with atrial, venous, and other visceral morphologies.

METHODS AND RESULTS

The morphology of the heart and other organs was examined in 275 iv/iv mice using criteria based on abnormal laterality in humans. The arrangement of the atrial appendages was determined by morphological examination of the junction between the appendage and the venous component of the atrium. On this basis, 45.1% of cases were shown to have usual atrial arrangement, 50.2% had mirror imagery, 1.5% had right isomerism, and 3.3% had left isomerism. Every case of atrial isomerism had a cardiac lesion; the morphological types were similar to those seen in human cases. Of cases with either usual or mirror-image arrangement of the appendages, 33.2% had abnormal spleens, but only 3.1% had cardiac defects. Similarly, venous abnormalities were much more common (30.1%) than cardiac defects.

CONCLUSIONS

Study results endorse the importance of the morphology of atrial appendages in predicting cardiac abnormalities and point to the marked inconsistency of the arrangement of other organs, including the spleen and the connections of the systemic veins.

Lobar bronchioloalveolar carcinoma: "angiogram sign" on CT scans

The authors reviewed computed tomographic (CT) scans of 12 patients with lobar bronchioloalveolar carcinoma. Seven patients had consolidation of the entire lobe, and five patients had segmental consolidation. After contrast material was administered intravenously, the consolidated lung typically appeared on the scan as an area of homogeneous low attenuation, within which were enhanced branching pulmonary vessels (the CT angiogram sign). To evaluate the specificity of this sign in the discrimination of bronchioloalveolar carcinoma, CT scans of 26 patients who had lobar consolidation from other diseases were randomly mixed with the CT scans of 11 patients with bronchioloalveolar carcinoma. Two independent observers who were unfamiliar with the cases classified 10 and nine of the 11 patients with bronchioloalveolar carcinoma, respectively, as positive for bronchioloalveolar carcinoma by applying the CT angiogram sign, and classified as negative 25 and 23 of the 26 patients without bronchioloalveolar carcinoma, respectively, for an overall specificity of 92.3%. The angiogram sign appeared on the CT scan because of the low-attenuating consolidation, which was caused by the production of mucin or other fluid and the intact bronchovascular framework within the tumor.

Extracellular Fluid/Intracellular Fluid Volume Ratio as a Novel Risk Indicator for All-Cause Mortality and Cardiovascular Disease in Hemodialysis Patients

Background

In hemodialysis patients, fluid overload and malnutrition are accompanied by extracellular fluid (ECF) expansion and intracellular fluid (ICF) depletion, respectively. We investigated the relationship between ECF/ICF ratio (as an integrated marker reflecting both fluid overload and malnutrition) and survival and cardiovascular disease (CVD) in the context of malnutrition-inflammation-arteriosclerosis (MIA) complex.

Methods

Seventy-seven patients from a single hemodialysis unit were prospectively enrolled. The ECF/ICF volume was measured by segmental multi-frequency bioimpedance analysis. MIA and volume status were measured by serum albumin, C-reactive protein (CRP), pulse wave velocity (PWV) and plasma B-type natriuretic peptide (BNP), respectively.

Results

The mean ECF/ICF ratio was 0.56±0.06 and the cut-off value for maximum discrimination of survival was 0.57. Compared with the low ECF/ICF group, the high ECF/ICF group (ratio≥0.57, 42%) had higher all-cause mortality, CVD, CRP, PWV, and BNP, but lower serum albumin. During the 5-year follow-up, 24 all-cause mortality and 38 CVD occurred (18 and 24, respectively, in the high ECF/ICF group versus 6 and 14 respectively in the low ECF/ICF group, P<0.001). In the adjusted Cox analysis, the ECF/ICF ratio nullifies the effects of the MIA and volume status on survival and CVD and was an independent predictor of all-cause mortality and CVD: hazard ratio (95% confidence interval); 1.12 (1.01–1.25) and 1.09 (1.01–1.18) for a 0.01 increase in the ECF/ICF ratio. The degree of malnutrition (albumin), inflammation (CRP), arteriosclerosis (PWV), and fluid overload (BNP) were correlated well with the ECF/ICF ratio.

Conclusions

Hemodialysis patients with high ECF/ICF ratio are not only fluid overloaded, but malnourished and have stiff artery with more inflammation. The ECF/ICF ratio is highly related to the MIA complex, and is a major risk indicator for all-cause mortality and CVD.

Morphology of the sinus node in human and mouse hearts with isomerism of the atrial appendages

BACKGROUND

The location of the sinus node is known to be at best abnormal, or at worst unknown, in patients with isomerism of the morphologically left atrial appendage. In contrast, the sinus node is known to be an excellent histological marker of the morphologically right appendage, being duplicated in those with right isomerism. The aim of the study was to investigate this condition further in fetal human and mouse hearts.

METHODS

Serial histological sections of the area anticipated to contain the sinus node were studied in hearts with isomerism of the atrial appendages taken from 14 human fetuses and 13 iv/iv mice, using 12 mouse hearts with normally arranged or mirror imaged atrial chambers for controls.

RESULTS

All hearts with isomerism of the right appendages (two human and four mouse) had bilateral sinus nodes. The cases with isomerism of the left appendages (12 human and nine mouse) showed absence of a recognisable sinus node except in four cases (19%) in which a small remnant of the node was found. In three of these cases, it was related postero-inferiorly to the superior cavoatrial junction.

CONCLUSIONS

The concept of isomerism of the atrial appendages is endorsed by findings on the morphology of the sinus node, this being the most reliable histological criterion for existence of a morphologically right atrium. A small proportion of hearts with left isomerism had a structure resembling the sinus node, but it was hypoplastic and displaced postero-inferiorly, distant from its expected position had the hearts possessed an incompletely formed morphologically right appendage.

Giant lymph node hyperplasia (Castleman's disease) in the chest

We have experienced 7 cases of giant lymph node hyperplasia in the chest from 1981 to 1992. The ages of the 1 male and 6 female patients ranged from 9.9 to 40.4 years (mean age, 29.2 +/- 10.4 years). In 4 patients, a mass was discovered in routine radiographs. Focal calcification suggesting continual enlargement over a long time was noted in 1 patient. The sites of lesions were unusual in 2 patients (intercostal space and intrapulmonary fissure). All patients underwent surgical removal of the mass. Five cases had typical features of the hyaline-vascular type, and 2 cases revealed a mixture of the hyaline-vascular type and the plasma-cell type. Follow-up was available in all patients (mean follow-up, 31.9 months). In 1 patient, recurrence was observed 9 years after surgical removal. In general, giant lymph node hyperplasia can occur anywhere in the chest, grow without symptoms, and recur in spite of complete resection. Surgical resection and close follow-up are advised.

Pathological changes according to the severity of asthma

BACKGROUND

There have been many studies concerning pathological changes in bronchial mucosa from asthmatics; however, few studies has been carried out to evaluate pathological changes according to the severity of asthma.

OBJECTIVE

This study was designed to evaluate the cellular components in bronchoalveolar lavage fluid (BALF) and histological abnormalities in asthmatics according to the severity of asthma.

METHODS

Bronchoalveolar lavages, bronchoscopic biopsies and ultrastructural examinations were performed in 13 asthmatics and 11 (BAL) or four (biopsies) non-asthmatic controls. The proportions of epithelial cells and correlations with PC20Meth which reflects bronchial hyperresponsiveness. Light microscopic examination revealed loss of epithelium, inflammatory cell infiltrations and thickening of the basement membrane which also showed significant correlation with PC20Meth. Hypertrophy of airway smooth muscles and hyperplasia of mucous glands were prominent in asthmatics but there was no difference according to the severity of asthma. Ultrastructural examination revealed that basement membrane thickening on light microscopic examination is due to the increased subepithelial collagen deposition with normal thickness of basal lamina.

CONCLUSION

These data suggest that loss of epithelial cells, infiltration of inflammatory cells, especially eosinophils, and increased deposition of subepithelial collagen play major roles in determining the severity of asthma and non-specific bronchial hyperresponsiveness.

Pulmonary lymphangioleiomyomatosis in Korea

BACKGROUND

Pulmonary lymphangioleiomyomatosis (LAM) is a rare disease occurring in women of reproductive age and leading to progressive respiratory failure in spite of treatment. In Korea the first case was reported in 1984 and by 1997 a total of 23 cases had been reported. The clinical findings of these Korean cases are reviewed.

METHODS

The details of 10 cases of LAM on file at Seoul National University Hospital were reviewed together with those of 13 cases previously reported from other Korean institutes. Two, including the only one to be reported in a man, were excluded after reviewing the clinical, radiological, and pathological findings, leaving a total of 21 cases in the present study.

RESULTS

All 21 patients were women and in all cases the disease was proven pathologically. The mean (SD) age at onset of symptoms was 32 (8.6) years. The most common symptoms were dyspnoea and pneumothorax which were seen in 19 (90%) and 13 (76%) patients, respectively. Pulmonary function tests showed decreased transfer factor (TLCO) (100%) and airflow limitation (67%). All the cases had characteristic cysts on high resolution computed tomographic (HRCT) scanning. The overall severity score based on HRCT scans correlated with the percentage predicted TLCO/VA (p = 0.03) and FEV1/FVC (p = 0.02). The patients were all treated with medroxyprogesterone and/or tamoxifen. Follow up was possible in 10 cases. Two of these patients appeared to stabilise with no appreciable change clinically or in lung function on medroxyprogesterone and/or tamoxifen, but the remaining patients all deteriorated with two dying of respiratory insufficiency and one of infection following lung transplantation.

CONCLUSIONS

As in other countries, in Korea LAM occurs exclusively in women and progresses despite hormonal treatment.

Adhesion mechanisms of the contact interface of TiO2 nanoparticles in films and aggregates

Fundamental knowledge about the mechanisms of adhesion between oxide particles with diameters of few nanometers is impeded by the difficulties associated with direct measurements of contact forces at such a small size scale. Here we develop a strategy based on AFM force spectroscopy combined with all-atom molecular dynamics simulations to quantify and explain the nature of the contact forces between 10 nm small TiO(2) nanoparticles. The method is based on the statistical analysis of the force peaks measured in repeated approaching/retracting loops of an AFM cantilever into a film of nanoparticle agglomerates and relies on the in-situ imaging of the film stretching behavior in an AFM/TEM setup. Sliding and rolling events first lead to local rearrangements in the film structure when subjected to tensile load, prior to its final rupture caused by the reversible detaching of individual nanoparticles. The associated contact force of about 2.5 nN is in quantitative agreement with the results of molecular dynamics simulations of the particle-particle detachment. We reveal that the contact forces are dominated by the structure of water layers adsorbed on the particles' surfaces at ambient conditions. This leads to nonmonotonous force-displacement curves that can be explained only in part by classical capillary effects and highlights the importance of considering explicitly the molecular nature of the adsorbates.

Cardiovascular system in conjoined twins: an analysis of 14 Korean cases

A new classification of cardiovascular system in conjoined twins is introduced. A special effort has been made to analyze the degree of fusion and symmetry of hearts and great vessels, based on 14 pairs of conjoined twins. The degree of cardiovascular union of the twins is classified into five types. Cases with no vascular union in cardiac, aortic, and inferior vena caval levels were grouped into type I (four cases). Cases with separate hearts and union between aortas or inferior venae cavae were grouped into type II (three cases). Cardiac fusion at the atrial level was grouped into type III (three cases). All of the three cases showed fusion between right atria (subtype IIIa). The theoretical fusion between the left atria or between the left and right atria is put into subtype IIIb. The type IV represents fusion of both atria and ventricles regardless of the number of the chambers (three cases). Type V represents single heart in one of the twins (one case). The external morphologic type and the situs of each twin pair were closely related to the cardiac abnormalities. Dicephalus and thoracopagus were more likely to be associated with abnormal situs and complex cardiac fusion. Abnormal situs was seen in seven out of 14 cases. Three cases with polysplenia and a case with asplenia showed more complex cardiac abnormalities than those with normal situs or situs inversus.

An optical and microPET assessment of thermally-sensitive liposome biodistribution in the Met-1 tumor model: Importance of formulation

The design of delivery vehicles that are stable in circulation but can be activated by exogenous energy sources is challenging. Our goals are to validate new imaging methods for the assessment of particle stability, to engineer stable and activatable particles and to assess accumulation of a hydrophilic model drug in an orthotopic tumor. Here, liposomes were injected into the tail vein of FVB mice containing bilateral Met-1 tumors and imaged in vivo using microPET and optical imaging techniques. Cryo-electron microscopy was applied to assess particle shape prior to injection, ex vivo fluorescence images of dissected tissues were acquired, excised tissue was further processed with a cell-digest preparation and assayed for fluorescence. We find that for a stable particle, in vivo tumor images of a hydrophilic model drug were highly correlated with PET images of the particle shell and ex vivo fluorescence images of processed tissue, R(2)=0.95 and R(2)=0.99 respectively. We demonstrate that the accumulation of a hydrophilic model drug is increased by up to 177 fold by liposomal encapsulation, as compared to accumulation of the drug at 24 hours.

Overexpression of HA-Bax but not Bcl-2 or Bcl-XL attenuates 6-hydroxydopamine-induced neuronal apoptosis

Bax, a member of the Bcl-2 gene family, is known to promote apoptosis in many cases but to block cell death under certain conditions. To investigate the potential role of Bax in 6-hydroxydopamine (6-OHDA)-induced cell death, we first established and characterized a dopaminergic neuronal cell line (MN9D) stably overexpressing hemagglutinin epitope-tagged Bax (MN9D/HA-Bax) as well as control clones (MN9D/Neo). Treatment of MN9D/Neo cells with 6-OHDA induced typical apoptotic cell death accompanied by shrinkage of the cell, nuclear condensation, and DNA fragmentation as demonstrated by light microscopy and agarose gel analysis. Overexpression of HA-Bax in MN9D cells was shown to attenuate 6-OHDA-induced cell death as determined by the MTT reduction assay and agarose gel analysis for DNA fragmentation. Western blot analysis revealed that cleavage of poly(ADP-ribose)polymerase induced by 6-OHDA was attenuated in MN9D/HA-Bax cells. In contrast, overexpression of a well-known cell death-inhibiting protein such as Bcl-2 or Bcl-XL did not attenuate 6-OHDA-induced cell death. Interestingly, cell death induced by hydrogen peroxide (0.25-2.0 mM) was significantly accelerated, whereas the rate of cell death induced by menadione (10-50 microM) was not affected in MN9D/HA-Bax cells. Thus, our present data suggest that the functionally diverse roles of Bax may be determined by the type of stress applied to the cell.

The first report of diffuse panbronchiolitis in Korea: five case reports

Diffuse panbronchiolitis (DPB), which is prevalent in Japan, is known to be rare outside Japan. Although a case of diffuse panbronchiolitis in a second generation Korean was reported in Japan in 1986, no case has been reported in Korea. Recently we found 5 cases of diffuse panbronchiolitis in Korea, two histologically proven and three clinically and radiologically suspected. All 5 cases had the typical respiratory symptoms and signs and a history of chronic sinusitis. In three clinically and radiologically suspected cases, high resolution computed tomography showed the typical findings of DPB and other diseases such as pulmonary emphysema, bronchial asthma, chronic bronchitis and bronchiectasis could be ruled out. More cases of DPB are expected to be found in Korea in the near future.

Apoptosis and regulation of Bax and Bcl-X proteins during human neonatal vascular remodeling

To verify that apoptosis is one of the possible mechanisms of neonatal vascular remodeling during the transition from fetal to neonatal circulation, we assayed for apoptosis and evaluated the expression of apoptosis-regulatory proteins in umbilical vessel versus ascending aorta, ductus arteriosus (DA) versus adjacent pulmonary artery and aorta, or aorta versus its branching arteries. Twenty-two umbilical cords (UCs), 6 DAs with adjacent aortas and pulmonary arteries, and 4 aortic arches with their branching great arteries were obtained from neonates. Smooth muscle cell (SMC) apoptosis in umbilical vessels was identified in all UCs. The expressions of Bax and Bcl-X were stronger in umbilical artery than in the neonatal aorta, but Bcl-2 was weak in both arteries in immunohistochemistry. In the immunoblot analysis of UCs, the expression of the proapoptotic short isoform of Bcl-X was stronger than in other tissue, and caspase-3 was selectively activated, whereas it was not in the other components of the cardiovascular system. In contrast, the expression patterns of the FasAg and Fas ligand were similar in umbilical artery and aorta. Regulation of Bcl-2 family proteins was also observed in other vascular sites at which SMCs undergo apoptosis on hemodynamic changes during birth, such as the DA and the branching points of the great arteries from the aortic arch. Apoptosis is involved in the regression of human umbilical vessels and the DA and in the remodeling of the branching great arteries during the neonatal period, when Bcl-2 family proteins are likely to play a key role.

Morphology of tricuspid valve in pulmonary atresia with intact ventricular septum

Pulmonary atresia with intact ventricular septum (PAIVS) is a rare congenital cardiac anomaly that has been classified into two types: one is a more frequent type having dysplasia of tricuspid valve (TV) with a small annulus, underdeveloped right ventricle (RV) with a hypoplastic cavity and a hypertrophic wall; the other type has severe dysplasia of TV and dilatation of RV, right atrium (RA), and right atrioventricular junction with thinning of the RV wall. We performed a morphologic study on 11 autopsied hearts with PAIVS, giving particular emphasis to the variation of morphology of the TV. We could classify these hearts into 3 groups according to the degree of right ventricular development. In the first group of 7 cases (type I), the RVs were underdeveloped. Thick leaflets, restricted valve apparatus with short chordae, and small annuli were characteristics of the TV. In the second group of 3 cases (type II), the RVs showed marked enlargement of the cavity and thinning of the wall. The TV showed redundant, dysplastic, sail-like anterior leaflets, and the downward displacement of septal leaflet and/or posterior leaflet, which are the findings frequently observed in Ebstein's malformation. The RVs were dilated and with partially unguarded tricuspid orifice. The septal leaflet of the TV was dysplastic and, in two cases, the septal leaflet showed chordal structure at the upper surface facing the RA, which is a peculiar finding that has not been described in the literature. The remaining case was a heart with a moderately developed RV (type III). The TV showed mildly dysplastic appearance and we classify this as a separate type, because we could expect the best surgical results in this type. This type had optimal size of RV and the mildest degree of dysplasia of TV. In PAIVS, the morphology of TV correlates well with the type of the right ventricular development.

Hearts with twisted atrioventricular connections: findings at MR imaging

The "crisscross" heart and the heart with "superoinferior ventricles" are closely related congenital cardiac malformations that are characterized by twisted atrioventricular connections. The authors studied the morphologic characteristics of three hearts with twisted atrioventricular connections as seen on magnetic resonance (MR) images. The most important clue to the diagnosis was the distorted atrioventricular connections that were demonstrated on serial images. The axes of the atrioventricular connections through the atrioventricular valves were not parallel to each other. The presence of unusual recesses in the cardiac chambers, the angulated or curved configuration of the atrial and ventricular septa, and the unexpected great arterial relationship for the given combination of segmental connections supported the findings of twisted atrioventricular connections. MR imaging facilitated the precise morphologic diagnosis of these hearts.

Microcystic adenomas of the pancreas. Report of three cases with two of multicentric origin

Three cases of microcystic adenomas of the pancreas with special reference to multicentric origin are described. The gross features and light microscopic findings were consistent with those described as being microcystic adenomas, but in two cases the gross examination and gelatin-embedded giant slices revealed multiple, isolated development of tumors ranging from submacroscopic nodules to tumors 4.5 cm in diameter. The larger tumors often showed ragged margins with small satellite nodules around the masses. A central fibrolamellar stellate core with centrifugally radiating septation was found in most of the tumor masses, even in the smaller ones. Ultrastructural and immunohistochemical findings revealed a single row of glycogen-rich epithelial cells, but participation of myoepithelial cells was not confirmed. Instead, vimentin-positive cells (pericytes) within the interstitial space incorporated closely with the basal lamina of the cyst wall. This study suggests that a small percentage of microcystic adenomas of the pancreas develop in multiple tumors, and some appear as a single tumor by their confluence.