[Introduction: chronic myelogenous leukemia leading advanced clinical oncology]

Our understanding of the pathological molecular events underlying chronic myelogenous leukemia(CML) has rapidly grown over the past 2 decades. At the same time, new therapeutic modalities for CML which can cure or prolong survival in this formerly incurable disease, including interferon alpha administration and allogeneic hematopoietic stem cell transplantation, have been established. Now, a new molecule-specific drug, a ABL tyrosine kinase inhibitor(STI571), are developing, which is offering new hope for expanded treatment options for patients with CML. Clinical investigators and medical doctors will have responsibility in helping newly diagnosed patients with CML to properly elect treatment planning among the increased options available now. This specific number of JJ CO will be hoped to provide information to many medical oncologists beyond the hematology speciality.

HSH2: a novel SH2 domain-containing adapter protein involved in tyrosine kinase signaling in hematopoietic cells

We isolated a cDNA clone encoding a novel Src homology (SH)2 domain-containing protein of 47 kDa from a human cDNA library. As its transcript was predominantly expressed in hematopoietic cells, this gene was termed HSH2 for hematopoietic SH2 protein. This protein contains several putative protein-binding motifs, SH3-binding proline-rich regions, and phosphotyrosine sites, but lacks enzymatic motifs. In a yeast two-hybrid screen, we identified a cytokine-regulated tyrosine kinase c-FES and an activated Cdc42-associated tyrosine kinase ACK1 as HSH2 interactors. HSH2 bound c-FES via its C-terminal region as well as its N-terminal region including the SH2 domain, whereas it bound ACK1 via its N-terminal proline-rich region. Furthermore, these two kinases bound and tyrosine-phosphorylated HSH2 in mammalian cells. Hence, we postulate that HSH2 functions as an adapter protein involved in tyrosine kinase signaling, and possibly regulates cytokine signaling and cytoskeletal reorganization, in hematopoietic cells.

STAT5 induces macrophage differentiation of M1 leukemia cells through activation of IL-6 production mediated by NF-kappaB p65

We recently demonstrated that STAT5 can induce a variety of biological functions in mouse IL-3-dependent Ba/F3 cells; STAT5-induced expression of pim-1, p21(WAF/Cip1), and suppressor of cytokine signaling-1/STAT-induced STAT inhibitor-1/Janus kinase binding protein is responsible for induction of proliferation, differentiation, and apoptosis, respectively. In the present study, using a constitutively active STAT5A (STAT5A1*6), we show that STAT5 induces macrophage differentiation of mouse leukemic M1 cells through a distinct mechanism, autocrine production of IL-6. The supernatant of STAT5A1*6-transduced cells contained sufficient concentrations of IL-6 to induce macrophage differentiation of parental M1 cells, and STAT3 was phosphorylated on their tyrosine residues in these cells. Treatment of the cells with anti-IL-6 blocking Abs profoundly inhibited the differentiation. We also found that the STAT5A1*6 transactivated the IL-6 promoter, which was mediated by the enhanced binding of NF-kappaB p65 (RelA) to the promoter region of IL-6. These findings indicate that STAT5A cooperates with Rel/NF-kappaB to induce production of IL-6, thereby inducing macrophage differentiation of M1 cells in an autocrine manner. In summary, we have shown a novel mechanism by which STAT5 induces its pleiotropic functions. Cytokines

Inhibitory effect of interleukin 3 on early development of human B-lymphopoiesis

Interleukin 3 (IL-3) is known as a stimulator of proliferation and differentiation of non-lymphoid cells, but information about the activity of IL-3 in lymphopoiesis is limited. In the present study, we examined the effect of IL-3 on human B-lymphopoiesis using the co-culture system on a murine stromal cell line, MS-5, with stem cell factor (SCF) and granulocyte colony-stimulating factor (G-CSF). Although a large number of CD45+CD19+ B cells were generated in the co-culture of cord blood CD34+ cells, the addition of IL-3 to the co-culture suppressed the B-cell generation in a dose-dependent manner. In the co-culture, CD34+IL-3 receptor alpha-chain (IL-3Ralpha)+ cells, but not IL-3Ralpha- cells, produced B cells, and IL-3 suppressed the B-cell generation from CD34+IL-3Ralpha+ cells, suggesting that IL-3 exerts an inhibitory effect through the binding to IL-3Ralpha on CD34+ cells. Because the delayed addition of IL-3 and the short-term exposure to IL-3 showed that IL-3 acted as an inhibitor at an early stage of B-cell development from CD34+ cells, before the generation of CD19+ B cells, the effect of IL-3 on the early development of B cells from immature CD34+CD38- cells was examined. Individual colonies, produced from clone-sorted CD34+CD38- cells by SCF, thrombopoietin and a complex of IL-6/soluble IL-6R with or without IL-3, were divided into two fractions and analysed for B-cell potential using co-culture on MS-5 with SCF and G-CSF, and haematopoietic potential using methylcellulose clonal culture. Although some colonies cultured without IL-3 showed both B-cell and haematopoietic potential, all the colonies cultured with IL-3 showed only haematopoietic potential. These results indicate that IL-3 has an inhibitory effect on the B-cell generation from human lymphohaematopoietic progenitor cells.

Glucocorticoid-regulated expression of exogenous human growth hormone gene in rats

The aim of this study was to control in vitro and in vivo expression of the growth hormone (GH) gene using a glucocorticoid-sensitive promoter, the mouse mammary tumor virus long terminal repeat (MMTV LTR). We inserted the cDNA encoding the 20-kDa form of human GH (20K-GH) downstream of the MMTV LTR of plasmid pMSG, and used lipofection to transfer it to 3Y1 cells together with plasmid pMX, which contains a puromycin-resistant element. The secretion of GH from the selected transformants was dose-dependently augmented by the application of hydrocortisone, corticosterone, or dexamethasone, among which dexamethasone was the most potent. Analysis of the time course showed that 20K-GH secretion began to increase within 2 hours after the addition of glucocorticoid and reached a maximal level of about threefold over the unstimulated control at 3 hours; secretion then gradually declined and returned to near basal levels at 19 hours. Repeated glucocorticoid application led to repeated increases in GH secretion. When GH-producing cells were microcapsulated and transplanted into the abdominal cavities of rats, 20K-GH was detected in the plasma under control conditions and increased about 3.3-fold after administration of dexamethasone. We suggest that GH expression driven by the MMTV LTR promoter may be under the control of an endogenous glucocorticoid in vivo.

Unrelated cord blood transplantation for adult patients with myelodysplastic syndrome-related secondary acute myeloid leukaemia

Seven adult patients with myelodysplastic syndrome (MDS)-related secondary acute myeloid leukaemia (AML) were treated with total body irradiation (TBI), cytosine arabinoside (Ara-C) and cyclophosphamide (CY), followed by unrelated human leucocyte antigen (HLA)-mismatched cord blood transplantation (CBT). Granulocyte colony-stimulating factor (G-CSF) was infused continuously from 12 h before until the end of Ara-C therapy to enhance the antileukaemia effect of Ara-C. Five patients are alive and free of disease at 7-31 months after transplantation. These preliminary results suggest that adult MDS-related secondary AML patients without suitable related or unrelated bone marrow donors should be considered as candidates for CBT.

Alanine-scanning mutagenesis of the sixth transmembrane segment of gastric H+,K+-ATPase alpha-subunit

The sixth transmembrane (M6) segment of the catalytic subunit plays an important role in the ion recognition and transport in the type II P-type ATPase families. In this study, we singly mutated all amino acid residues in the M6 segment of gastric H(+),K(+)-ATPase alpha-subunit with alanine, expressed the mutants in HEK-293 cells, and studied the effects of the mutation on the functions of H(+),K(+)-ATPase; overall K(+)-stimulated ATPase, phosphorylation, and dephosphorylation. Four mutants, L819A, D826A, I827A, and L833A, completely lost the K(+)-ATPase activity. Mutant L819A was phosphorylated but hardly dephosphorylated in the presence of K(+), whereas mutants D826A, I827A, and L833A were not phosphorylated from ATP. We found that almost all of these amino acid residues, which are important for the function, are located on the same side of the alpha-helix of the M6 segment. In addition, we found that amino acids involved in the phosphorylation are located exclusively in the cytoplasmic half of the M6 segment and those involved in the K(+)-dependent dephosphorylation are in the luminal half. Several mutants such as I821A, L823A, T825A, and P829A partly retained the K(+)-ATPase activity accompanying the decrease in the rate of phosphorylation.

Severe autoimmune thrombocytopenia after allogeneic bone marrow transplantation for aplastic anemia

Autoimmune thrombocytopenia (AITP) after bone marrow transplantation (BMT) was suggested to occur by immune dysregulation mainly in association with graft-versus-host disease (GVHD). Here we present a patient who developed severe AITP after BMT. A 40-year-old woman with severe aplastic anemia received a BMT from a partially HLA-matched brother. Despite myeloid and erythroid engraftments, platelet recovery was delayed. All bone marrow cells were 46,XY and were derived from the donor. Grade I acute GVHD involving skin developed from day 34 posttransplantation, but promptly responded to prednisolone in addition to a prophylactic dose of tacrolimus. With the tapering of prednisolone, thrombocytopenia progressed without substantial changes in the white blood cell count, hemoglobin concentration, or reticulocyte count. On day 188, the patient developed chronic GVHD involving skin and liver, which promptly responded to the readministration of prednisolone and increased tacrolimus. However, the patient's platelet count decreased to 9 x 10(9) cells/L on day 222. The platelet-associated immunoglobulin G (PAIgG) values were elevated. Bone marrow examination showed hypercellularity with plentiful megakaryocytes. The number of colony-forming units-megakaryocyte was within the normal range. The elevated PAIgG values and a correlation between thrombocytopenia and the intensity of the immunosuppressive agents strongly suggested a causative role of the autoimmune mechanisms for thrombocytopenia in this patient.

Generation of definitive hematopoietic stem cells from murine early yolk sac and paraaortic splanchnopleures by aorta-gonad-mesonephros region-derived stromal cells

There is controversy as to whether murine definitive hematopoiesis originates from yolk sac (YS) or the intraembryonic region. This study reports the generation of definitive hematopoietic stem cells (HSCs) from both early YS and intraembryonic paraaortic splanchnopleures (P-Sp) on AGM-S3 stromal cells derived from the aorta-gonad-mesonephros (AGM) region at 10.5 days post coitum (dpc). YS and P-Sp cells at 8.5 dpc generated no definitive hematopoiesis-derived colony-forming cells in cocultures with AGM-S3 cells, but spleen colony-forming cells and HSCs capable of reconstituting definitive hematopoiesis in adult mice simultaneously appeared on day 4 of coculture. Precursors for definitive HSCs were present in YS and P-Sp at 8.0 dpc, a time when YS and embryo were not connected by blood vessels. It is proposed that precursors with the potential to generate definitive HSCs appear independently in YS and intraembryonic P-Sp and that the P-Sp or AGM region affords the microenvironment that facilitates generation of definitive hematopoiesis from precursors.

Decreased tensile strength of an epidural catheter during its removal by grasping with a hemostat

IMPLICATIONS

Our case suggests that gripping an epidural catheter with a hemostat during the removal might result in accidental breakage of the catheter. To demonstrate the effect of the use of a hemostat, tensile strengths of catheters were measured while they were being held with either a stainless steel or rubber-sleeved hemostat.

Tandem repetition of baculovirus ie1 promoter results in upregulation of transcription

In order to improve a virus-independent gene expression system in insect cells, the effect of the repetition of the promoter sequence of a baculovirus immediate early gene, BmNPV ie1, on the gene expression activity was examined. Tandem repetition of ie1 promoter resulted in about a 4-fold increase of the reporter gene expression activity. Primer extension analysis revealed that the repetition increased not only the amount of transcripts (4 to 5-times) but also the number of sites of transcription initiation (at least 3 extra initiation sites). A mutational experiment demonstrated the involvement of independent cis-acting elements in these two different promoter-enhancing effects.

Development of human lymphohematopoietic stem and progenitor cells defined by expression of CD34 and CD81

In this study, cord blood CD34(+) cells expressed CD81, a member of the transmembrane 4 superfamily, and were classified into 3 subpopulations on the basis of their expression levels: CD34(+)CD81(+), CD34(low)CD81(+), and CD34(+)CD81(high). The lymphohematopoietic activity of each subpopulation was then examined by using suspension and clonogenic cultures for hematopoietic potential, coculture with MS-5 cells for B-cell potential, organ cultures of thymus lobes from nonobese diabetic/severe combined immunodeficiency disease (NOD/SCID) fetal mice, coculture with stromal cells derived from NOD/SCID fetal-mouse liver tissue for natural killer (NK) cell and mast cell potentials, and xenotransplantation into NOD/SCID mice for long-term repopulating (LTR) ability. CD34(+)CD81(+) cells represented a heterogeneous population that had all the lymphohematopoietic activities, including NOD/SCID mouse-repopulating ability. CD34(low)CD81(+) cells were enriched in erythroid, megakaryocytic, and NK lineage potentials but had lost T-cell and B-cell potentials and LTR ability. The CD34(+)CD81(high) fraction was depleted of most lymphohematopoietic potentials except NK cell and mast cell potentials. Thus, along the differentiation cascade from CD34(+)CD81(+) lymphohematopoietic stem cells, an up-regulation of CD81 or a down-regulation of CD34 results in a change in lymphohematopoietic properties. CD81 may serve as a marker for defining developmental stages of lymphohematopoietic stem cells. (Blood. 2001;97:3755-3762)

[Present status and future problems of clinical laboratory from view points of an anatomical pathologist]

The medical situation surrounding laboratory examinations has changed remarkably. We, the staff of laboratory divisions, must offer the best medical care for patients and operate efficiently. Fertility management service(FMS) and branch laboratory(Branch Lab.) are examples of useful contributions to our hospital from the perspective of economy and personnel expenditure including staff attrition.

A novel secreted form of immune suppressor factor with high homology to vacuolar ATPases identified by a forward genetic approach of functional screening based on cell proliferation

In the search for stromal-derived growth factors, we have identified a novel secreted short form of immune suppressor factor (ISF) using a combination of a genetic approach and retrovirus-mediated functional screening. This protein, which we termed ShIF, was isolated based on its ability to support proliferation of a mutant clone S21, which was established from Ba/F3 cells that are usually interleukin-3-dependent but became dependent on a stroma cell line ST2 after chemical mutagenesis. ISF, a membrane protein harboring six transmembrane domains, was reported to have immunosuppressive functions. The coding region of ShIF started from the third transmembrane domain of ISF. Biochemical analysis demonstrated that ShIF was expressed in both the secreted and membrane-bound forms of 27-kDa protein, which was supposed to have an internal ATG present in the third transmembrane domain of ISF as a start codon. In addition to the full-length form of ISF, a major protein with a molecular size of 27 kDa was also expressed through the proteolytic process of ISF. ShIF resembles this naturally occurring short form of ISF (sISF). Deletion analysis of the major domains of ISF cDNA revealed that ShIF is an active functional domain of ISF with a capability to support proliferation of S21 cells. Enforced expression of ShIF in MS10 cells, bone marrow stroma cells that do not express endogenous ShIF or ISF, conferred on the cells an ability to support the growth of S21 cells as well as bone marrow cells. Interestingly, ShIF shows a high sequence homology to the C-terminal part of a 95-kDa yeast vacuolar H (+)-ATPase subunit, Vph1p (39%), and a 116-kDa proton pump (VPP1) (54%) of the rat and bovine synaptic vesicle. Therefore, it is possible that ShIF also acts as a proton pump and somehow prevents the cells from undergoing apoptosis.

Prompt and durable hematopoietic reconstitution by unrelated cord blood transplantation in a child with Fanconi anemia

We describe here the case of an 8-year-old girl with Fanconi anemia (FA) whose hematopoiesis was successfully restored by unrelated umbilical cord blood (UCB) transplantation. The patient became resistant to androgen therapy, and developed intracranial hemorrhage and dyserythropoiesis. Her hematopoietic recovery after the transplantation was excellent and a complete chimerism has been durably maintained. UCB should be considered as a stem cell source for transplantation when a patient with FA does not have an HLA-identical unaffected sibling donor.

Phosphatidylinositol-specific-phospholipase C cleaves urokinase plasminogen activator receptor from the cell surface and leads to inhibition of pemphigus-IgG-induced acantholysis in DJM-1 cells, a squamous cell carcinoma line

We showed previously that pemphigus IgG enhanced both the activity of urokinase plasminogen activator (uPA) in cultured cells and the expression of its receptor (uPAR) on uPA-binding keratinocytes. In the present study, to clarify whether uPAR and uPA-activated plasmin are actually involved in the blistering process after pemphigus IgG binding to the cell surface, we examined the effects of the following on uPAR expression and on cell-cell detachment in DJM-1 cells, a squamous cell carcinoma line: (i) phosphatidylinositol-specific phospholipase C (PI-PLC) - which releases uPAR from the membrane surface into the culture medium by cleaving the glycosylphosphatidylinositol anchor thus inhibiting uPAR activity, and (ii) uPA inhibitors (tranexamic acid, aprotinin, p-aminobenzonic acid and dexamethasone). Preincubation with PI-PLC decreased dramatically the pemphigus IgG-induced uPAR expression in a dose-dependent manner, and inhibited pemphigus IgG-induced cell-cell detachment at 10 microg/mL. On the other hand, tranexamic acid (15 mM) inhibited pemphigus IgG-induced cell-cell detachment without reduction of uPAR expression, although aprotinin, p-aminobenzonic acid and dexamethasone failed to alter either of these parameters. Although uPAR expression on the pemphigus IgG-bound cell surface and uPA activation may contribute significantly to the pathogenesis of acantholysis in pemphigus, the mechanisms are complicated and should be defined further.

[Septic shock due to pyonephrosis-calculosa: a case report]

A 69-year-old female was admitted to hospital with the complaint of high-grade fever and clouding of consciousness. Physical examination and laboratory data revealed septic shock, disseminated intravascular coagulation and multiple organ failure. Ultrasonography demonstrated left hydronephrosis and a cystic mass in peri-renal fatty tissue. KUB showed a left ureteral stone. A diagnosis of septic shock due to pyonephrosis-calculosa and peri-renal abscess was considered. A left nephrectomy, endotoxin removal therapy and continuous hemodiafiltration was performed. Thereafter all morbidities improved. A nephrectomy and intensive treatment are the good alternative method for such a case.

Dissecting aneurysms at the A1 segment of the anterior cerebral artery--two case reports

Two rare cases of dissections which involve the anterior cerebral artery (ACA) are reported. A 58-year-old woman presented with a ruptured dissecting aneurysm manifesting as sudden onset of severe headache and consciousness disturbance followed by aphasia, right hemiparesis, paresis of the left lower extremity, and choreoathetotic movements of the upper arms and face. Computed tomography and angiography revealed subarachnoid hemorrhage due to a dissecting aneurysm at the left A1 segment. The dissecting aneurysm was trapped surgically on the day of onset. Her neurological deficits disappeared within a month. A 39-year-old woman experienced continuous dull headache from the day before onset, and then suffered right hemiparesis. Magnetic resonance (MR) imaging revealed cerebral infarction at the left globus pallidus. Angiography and MR imaging revealed a dissecting aneurysm at the left A1 segment and occlusion of the left Heubner's artery. She received conservative treatment and her neurological findings were improved. Dissections or dissecting aneurysms involving the ACA can be classified into three types: Extension of a dissection to the ACA from the internal carotid artery, dissection at the A1 segment, and dissection at the A2-A4 segments. These types of dissection have distinct uniform clinical features.

Evidence for the presence of murine primitive megakaryocytopoiesis in the early yolk sac

During mouse embryogenesis, primitive erythropoiesis occurs in blood islands of the yolk sac (YS) on the seventh day of gestation. This study demonstrated for the first time the presence of unique primitive megakaryocytic (Mk) progenitors in the early YS, which disappeared by 13.5 days postcoitum (dpc). When 7.5 dpc YS cells were incubated in the presence of stem cell factor (SCF), interleukin (IL)-3, IL-6, erythropoietin (EPO), thrombopoietin (TPO), and granulocyte colony-stimulating factor in methylcellulose clonal culture, not only erythroid bursts but also megakaryocyte colonies were observed. The megakaryocytes in the colonies matured to proplatelet stages and produced platelets as early as day 3 of culture, much earlier than those from adult bone marrow, although their ploidy class was lower. These megakaryocytes were stained with acetylcholine esterase, and expressed platelet glycoprotein (GP)Ib beta, GPIIIa, and platelet factor 4 by reverse transcription-polymerase chain reaction analysis. The analysis of hemoglobin types in erythrocytes obtained from hematopoietic multilineage colonies containing the megakaryocytes indicated that the Mk progenitors originated from primitive hematopoiesis. The primitive Mk progenitors formed colonies in the absence of any cytokines in fetal bovine serum (FBS)-containing culture, and SCF, IL-3, EPO, and TPO significantly enhanced the Mk colony formation. In FBS-free culture, however, no colony formation was induced without these cytokines. Because megakaryocytes were detected in 8.5-dpc YS, these unique primitive Mk progenitors may rapidly mature and give rise to platelets to prevent hemorrhage in the simultaneously developing blood vessels until definitive hematopoiesis begins to produce platelets. (Blood. 2001;97:2016-2022)

Haematopoietic progenitor cells from the common marmoset as targets of gene transduction by retroviral and adenoviral vectors

To establish a new non-human primate model for human cytokine and gene therapy, we characterized lymphocytes and haematopoietic progenitor cells of the small New World monkey, the common marmoset. We first assessed the reactions of marmoset bone marrow (BM) and peripheral blood (PB) cells to mouse anti-human monoclonal antibodies (mAbs) for the purpose of isolating marmoset lymphocytes and haematopoietic progenitor cells. Both cell fractions stained with CD4 and CD8 mAbs were identified as lymphocytes by cell proliferation assay and morphological examination. Myeloid-specific mAbs such as CD14 and CD33 did not react with marmoset BM and PB cells. No available CD34 and c-kit mAbs could be used to purify the marmoset haematopoietic progenitor cells. Furthermore, we studied the in vitro transduction of the bacterial beta-galactosidase (LacZ) gene into CFU-GM derived from marmoset BM using retroviral and adenoviral vectors. The transduction efficiency was increased by using a mixed culture system consisting of marmoset BM stromal cells and retroviral producer cells. It was also possible to transduce LacZ gene into marmoset haematopoietic progenitor cells with adenoviral vectors as well as retroviral vectors. The percentage of adenovirally transduced LacZ-positive clusters was 15% at day 4 (multiplicity of infection=200), but only 1-2% at day 14. The differential use of viral vector systems is to be recommended in targeting different diseases. Our results suggested that marmoset BM progenitor cells were available to examine the transduction efficiency of various viral vectors in vitro.

Coronin forms a stable dimer through its C-terminal coiled coil region: an implicated role in its localization to cell periphery

BACKGROUND

Coronin is an actin-binding protein, which contains WD (Trp-Asp) repeats and a coiled-coil motif, and plays a role in regulating organization of the actin cytoskeletal network. Coronin localizes to the cell periphery, is involved in lamellipodium extension, and has an implicated role in cytokinesis, cell motility and phagocytosis.

RESULTS

Our experiments with two different tagged forms of Xenopus coronin (Xcoronin) have shown that Xcoronin forms an oligomer. This oligomer complex is stable, resistant to 2.4 M NaCl, 0.6 M KI or 2 M urea. Physiochemical analysis of endogenous Xcoronin and the protein expressed in COS7 cells or in bacteria has revealed that the oligomer complex is an Xcoronin dimer. A C-terminal coiled-coil motif of Xcoronin is necessary and sufficient for the dimerization. Mutations in the coiled-coil motif generated dimerization deficient mutants of Xcoronin. Moreover, these mutant forms of Xcoronin failed to localize to the cell periphery, suggesting that dimerization is important for the proper subcellular localization of Xcoronin.

CONCLUSION

Xcoronin forms a stable dimer via its C-terminal coiled-coil region. We propose that coronin dimerization is necessary for its proper subcellular localization and function.

Management of nodular goiters and their operative indications

It remains controversial whether or not nodular goiters should be treated surgically or conservatively. This report reviews our 9-year experience of treating nodular goiters in 334 patients, 44 of whom underwent surgery, and compares the methods of treatment employed from 1990 to 1999 with those employed from 1971 to 1989 when 171 operations were carried out. In accordance with diagnoses made using fine-needle aspiration biopsy (FNAB) and ultrasonography, patients were treated as follows. Those with cysts were given percutaneous ethanol injection therapy (PEIT), and those with solid tumors underwent surgery if cancer of >class 3 was suspected or if the tumors were >3 cm. Consequently, 44 patients with solid tumors underwent surgery and 72 with cysts were treated by PEIT. The number of operations performed annually decreased to half of the pre-1990 figure. During the follow-up of those patients who did not undergo surgery, four with solid tumors and two with cysts later required surgery due to suspected carcinoma of >class 3 in 3 patients or as a result of personal choice in 3 patients. The growth of solid tumors was not able to be measured in most cases. These results indicate that the number of operations performed for nodular goiters can be reduced by PEIT. An accurate cytological diagnosis supports this therapeutic strategy.