Management of primary and renal hyperparathyroidism: guidelines from the German Association of Endocrine Surgeons (CAEK).

BACKGROUND AND AIMS: The purpose of this review is to provide updated recommendations for the surgical management of primary (pHPT) and renal (rHPT) hyperparathyroidism, formulating a new guideline of the German Association of Endocrine Surgeons (CAEK). METHODS: Evidence-based recommendations for the diagnosis and therapy of pHPT and rHPT were assessed by a multidisciplinary panel using PubMed for a comprehensive literature search together with a structured consensus dialogue (S2k guideline of the Association of the German Scientific Medical Societies, AWMF). RESULTS: During the last 20 years, a variety of new preoperative localization procedures, such as sestamibi-SPECT, 4D-CT, and various PET/CT procedures, were established for pHPT. High-resolution imaging, together with intraoperative parathyroid hormone (IOPTH) measurement, enabled focused or minimally invasive surgery to become the most favored surgical technique. Patients with pHPT and nonlocalizing imaging have a higher risk of multiglandular disease. Surgical therapy provides very high cure rates, with a clear relation to the surgeon's experience in parathyroid procedures. Reoperative parathyroidectomy, children with pHPT or familial forms, and parathyroid carcinoma are addressed and require special surgical expertise. A multidisciplinary team of experienced nephrologists, transplant, and endocrine surgeons should assess the diagnosis and treatment of renal HPT. CONCLUSION: Surgery is the only curative treatment for pHPT and should be considered for all patients with pHPT. For rHPT, a more selective approach is required, and parathyroidectomy is indicated only when conservative treatment options fail. In parathyroid carcinoma, the adequacy of local resection influences local disease control.

Surgical therapy of adrenal tumors: guidelines from the German Association of Endocrine Surgeons (CAEK).

BACKGROUND AND AIMS: Previous guidelines addressing surgery of adrenal tumors required actualization in adaption of developments in the area. The present guideline aims to provide practical and qualified recommendations on an evidence-based level reviewing the prevalent literature for the surgical therapy of adrenal tumors referring to patients of all age groups in operative medicine who require adrenal surgery. It primarily addresses general and visceral surgeons but offers information for all medical doctors related to conservative, ambulatory or inpatient care, rehabilitation, and general practice as well as pediatrics. It extends to interested patients to improve the knowledge and participation in the decision-making process regarding indications and methods of management of adrenal tumors. Furthermore, it provides effective medical options for the surgical treatment of adrenal lesions and balances positive and negative effects. Specific clinical questions addressed refer to indication, diagnostic procedures, effective therapeutic alternatives to surgery, type and extent of surgery, and postoperative management and follow-up regime. METHODS: A PubMed research using specific key words identified literature to be considered and was evaluated for evidence previous to a formal Delphi decision process that finalized consented recommendations in a multidisciplinary setting. RESULTS: Overall, 12 general and 52 specific recommendations regarding surgery for adrenal tumors were generated and complementary comments provided. CONCLUSION: Effective and balanced medical options for the surgical treatment of adrenal tumors are provided on evidence-base. Specific clinical questions regarding indication, diagnostic procedures, alternatives to and type as well as extent of surgery for adrenal tumors including postoperative management are addressed.

Severe Graves' ophthalmopathy may be a risk factor for the development of postthyroidectomy hypocalcaemia.

PURPOSE: The aim of this study was to compare the rate of hypocalcaemia after thyroid resection in patients with versus patients without Graves' Ophthalmopathy (GO). PATIENTS AND METHODS: 153 patients following thyroid surgery for Grave's disease were studied. Patients were divided into three groups according to the severity of GO at the time of surgery using the NOSPECS classification. Subgroup I comprised of 70 patients without GO, subgroup II comprised of 63 patients with moderate GO and 20 patients with severe GO were assigned to Subgroup III. Association between severe ophthalmopathy and postoperative hypocalcaemia after thyroidectomy was investigated. RESULTS: 12/70 patients complained transient and 3/70 permanent hypocalcemia within subgroup I. 14/63 patients developed transient and 4/63 patients permanent hypocalcaemia within subgroup II. There were 7/20 patients with transient and 5/20 cases with permanent hypocalcaemia in the patient group with severe GO (subgroup III). The incidence of permanent postthyroidectomy hypocalcaemia was significantly higher in the subgroup III with severe GO when compared to the subgroup I without GO (p=0.004). CONCLUSION: Although postthyroidectomy hypocalcemia seems to be a multifactorial phenomenon, this study implicates unknown role of severe GO at time of surgery in the development of hypocalcaemia after thyroid surgery for Graves' disease. Therefore, patients with GO should be considered for surgery at high volume centres specialised in thyroid and parathyroid surgery.

Long-term results of surgical treatment in Graves' disease orbitopathy. Is there a correlation between the extent of thyroidectomy and the course of orbithopathy?

UNLABELLED: The place of thyroidectomy in the management of the Graves' disease patients with endocrine orbitopathy (EO) is still controversial. The aim of this study was to evaluate the course of EO according to the extent of thyroid resection. METHODS: A retrospective cross-sectional study was performed on a series of 171 cases of Graves'disease, operated in the period 1987-2002 in the Department of Surgery of the Philipps University, Marburg. The severity of EO at the time of operation was assessed according to NOSPECS classification and a structured telephone interview was conducted in order to appraise the long term results. RESULTS: Complete data acquisition was possible in 153 patients (89%). There were 123 women with a median age of 36 years (range 10-75) and 30 men with a median age of 33 years (range 22-65). Concerning the severity of EO, 70 patients (45.8%) had no ocular symptoms (group I). The 83 patients with clinical eye disease were divided in group II--63 patients (76%) with moderate syndrome and group III--20 patients (24%) with marked symptoms of EO. 12 patients received total thyroidectomy, 96 had Dunhill-resection and in 45 patients subtotal resection was performed. A median follow-up period of 96 months (range 12-216 months) was recorded. Post-operatively, of the 83 patients with EO, 53 patients (63.8%) declared an improvement of EO, in 29 patients (34.9%) the disease was stable and only one patient declared the worsening of EO. The extent of thyroid resection did not correlate with the postoperative course of orbitopathy. CONCLUSION: Thyroid surgery for GD improves the course of EO, independent of the extent of resection.

Analysis by cDNA microarrays of gene expression patterns of human adrenocortical tumors.

OBJECTIVES: Adrenocortical carcinoma (ACC) is a rare malignant neoplasm with extremely poor prognosis. The molecular mechanisms of adrenocortical tumorigenesis are still not well understood. The comparative analysis by cDNA microarrays of gene-expression patterns of benign and malignant adrenocortical tumors allows us to identify new tumor-suppressor genes and proto-oncogenes underlying adrenocortical tumorigenesis. DESIGN AND METHODS: Total RNA from fresh-frozen tissue of 10 ACC and 10 benign adrenocortical adenomas was isolated after histologic confirmation of neoplastic cellularity of at least 85%. The reference consisted of pooled RNA of 10 normal adrenal cortex samples. Amplified RNA of tumor and reference was used to synthesize Cy3- and Cy5-fluorescently labeled cDNA in a flip-color technique. D-chips containing 11 540 DNA spots were hybridized and scanned and the images were analyzed by ImaGene 3.0 software. RESULTS: The comparative analysis of gene expression revealed many genes with more than fourfold expression difference between ACC and normal tissue (42 genes), cortical adenoma and normal tissue (11 genes), and ACC and cortical adenoma (21 genes) respectively. As confirmed by real-time PCR, the IGF2 gene was significantly upregulated in ACCs versus cortical adenomas and normal cortical tissue. Genes that were downregulated in adrenocortical tumors included chromogranin B and early growth response factor 1. CONCLUSIONS: Comprehensive expression profiling of adrenocortical tumors by the cDNA microarray technique is a very powerful tool to elucidate the molecular steps associated with the tumorigenesis of these ill-defined neoplasms. To evaluate the role of identified genes, further detailed analyses, including correlation with clinical data, are required.

Antisense p53 oligonucleotides inhibit proliferation and induce chemosensitivity in follicular thyroid cancer cells.

BACKGROUND: The potential of MTp53 knockout by oligodesoxyribonucleotide phosphothioates (ODNs) to affect proliferation, apoptosis and chemosensitivity in undifferentiated thyroid cancer (UTC) cells with a recessive MTp53 mutation was evaluated. MATERIALS AND METHODS: Transient transfections with ODNs complementary to p53 and control ODN (HIV-RT) were carried out in FTC 133 cells. In vitro proliferation was evaluated by cell counting of 10 random fields and by the MTT assay. A single pulse of 100 microg/ml Cytarabine was added to each well and the cells were incubated for an additional day. Chemosensitivity was calculated as the ratio of apoptotic and necrotic cells versus viable cells by flow cytometry (FACS). RESULTS: Transfection of UTC cells with ODN decreased the cell number by up to 70% (p < 0.002). The proliferation rate also decreased up to 35% (p < 0.03), without inducing apoptosis. ODNs rendered FTC cells sensitive to treatment with Cytarabine, inducing apoptosis in 35% of cells, as compared to 17% of cells transfected with the reverse transcriptase gene of HIV (ODN-HIV) and less than 10% of non-transfected cells (p < 0.05). CONCLUSION: Transient MTp53 knockout with ODNs complementary to p53 nucleotide sequences inhibited proliferation and increased chemosensitivity in the UTC cell line FTC133.

Clinical background is required for optimum performance with a VR laparoscopy simulator.

OBJECTIVE: To determine the role of clinical background when assessing the learning effect using a virtual-reality (VR) laparoscopy simulator (LapSim). MATERIALS AND METHODS: Test subjects were 12 final-year medical students (Group A) and 12 inexperienced residents (Group B) with no previous experience of VR simulators. First, to establish a baseline, both groups performed the "clip application" task twice. They then completed a training program of increasing difficulty (coordination, cutting and clip application), after which both groups were re-tested using a difficult level of the "cutting" task as an endpoint measurement. Time to complete the tasks, as well as trauma and precision parameters, were scored. RESULTS: Before training, times to complete the baseline task, as well as parameters of trauma and precision, were similar for both groups. After training, Group B (residents) completed the cutting task significantly faster than Group A (students). However, the former group also showed significant improvement in trauma and precision parameter scores in the endpoint measurement. CONCLUSION: These results suggest that clinical background and understanding of the clinical value of a training program lead to faster acquisition and improvement of laparoscopic skills as performed on the laparoscopy simulator. Thus, medical students or other personnel not involved in practical surgery may be unsuitable as candidates for assessing the value of a VR training program.

Differential pattern of integrin receptor expression in differentiated and anaplastic thyroid cancer cell lines.

Adhesion of tumor cells to the extracellular matrix (ECM) is a crucial step for the development of metastatic disease and is mediated by specific integrin receptor molecules (IRM). The pattern of metastatic spread differs substantially among the various histotypes of thyroid cancer (TC). However, IRM have only occasionally been characterized in TC until now. IRM expression was investigated in 10 differentiated (FTC133, 236, 238, HTC, HTC TSHr, XTC, PTC4.0/4.2, TPC1, Kat5) and two anaplastic TC cell lines (ATC, C643, Hth74), primary cultures of normal thyroid tissue (Thy1,3), and thyroid cancer specimens (TCS). Expression of 16 IRM (beta1-4, beta7, alpha1-6, alphaV, alphaIIb, alphaL, alphaM, alphaX) and of four IRM heterodimers (alpha2beta1, alpha5beta1, alphaVbeta3, alphaVbeta5), was analyzed by fluorescent-activated cell sorter (FACS) and immunohistochemical staining. Thyroid tumor cell adhesion to ECM proteins and their IRM expression in response to thyrotropin (TSH) was assessed. Follicular TC cell lines presented high levels of integrins alpha2, alpha3, alpha5, beta1, beta3 and low levels of alpha1, whereas papillary lines expressed a heterogenous pattern of IRM, dominated by alpha5 and beta1. ATC mainly displayed integrins alpha2, alpha3, alpha5, alpha6, beta1 and low levels of alpha1, alpha4 and alphaV. Integrin heterodimers correlated with monomer expression. Evaluation of TCS largely confirmed these results with few exceptions, namely alpha4, alpha6, and beta3. The ability of TC cell lines to adhere to purified ECM proteins correlated with IRM expression. TSH induced TC cell adhesion in a dose-dependent fashion, despite an unchanged array of IRM expression or level of a particular IRM. Thyroid carcinoma cell lines of different histogenetic background display profoundly different patterns of IRM expression that appear to correlate with tumor aggressiveness. In vitro adhesion to ECM proteins and IRM expression concur. Finally, TSH-stimulated adhesion of thyroid tumor cell lines to ECM may not be associated with altered IRM expression.

An authentic malignant epithelioid hemangioendothelioma of the thyroid: a case report and review of the literature.

Hemangioendotheliomas of the thyroid are neoplasms that are rarely encountered in the Alpine region in Europe. The endemic goiter in this iodine-deficient region can be considered as a predisposing factor. We report the second case of an epithelioid hemangioendothelioma (EHE) of the thyroid gland and the first clinical case with malignant behavior. A 73-year-old woman with a long history of multinodular goiter presented with a rapidly growing thyroid mass, free of distant metastases. A total thyroidectomy was performed. Histologically the lesion had characteristic epithelioid and spindle cell proliferation in a background of chondromyxoid stroma. Cytoplasmic vacuolization in the epithelioid and spindle cells were present. Tumor cells were positive for factor VIII-related antigen, MNF116, PAN-ceratin, CD 34, and CD 31 and negative for cytokeratin allowing the diagnosis of EHE. Nine months after the primary resection the tumor locally recurred. A palliative resection was performed in a second operation followed by interferon-alpha therapy. The patient rapidly developed a second local relapse and died 13 months after the diagnosis of an EHE had been made. An improvement of the very poor prognosis of this rare tumor may depend on early tumor diagnosis and surgery combined with a multimodal treatment.

Endoscopic ultrasound imaging of insulinomas: limitations and clinical relevance.

Compared to other imaging methods, endoscopic ultrasound is the best procedure to localize insulinomas preoperatively. Positive finding furthermore confirms endocrinological diagnosis, especially considering the differential diagnosis of hypoglycaemia factitia by oral antidiabetics. However, it always has to be considered that endoscopic ultrasound imaging may reveal false positive and false negative results, and quality of the findings obtained by endoscopic ultrasound imaging depends to a large extent on the examiner's experience. An important issue of endoscopic ultrasound imaging in insulinomas nowadays is planning surgical strategy. As illustrated by three cases, endoscopic ultrasound imaging enables to identify patients that qualify for laparoscopic, minimal invasive surgery.

[Reoperation for primary hyperparathyroidism]. / Reoperationen beim primären Hyperparathyreoidismus Erfahrungen aus der Literatur und 106 eigenen Reoperationen.

While the initial treatment for primary hyperparathyroidism (pHPT), if managed by an experienced surgeon, is almost always successful, reoperations are challenging. Patients are at high risk for complications and the rates of success are plainly below those of primary cervical explorations. In this paper the reasons for failure during initial procedures are reviewed, as are the most important localization procedures and the prerequisites with regard to technical infrastructure as well as personnel, when planning repeat operations for a missed parathyroid adenoma. Provided that a standardized diagnostic and surgical approach is used, the surgeon is experienced, and up-to-date technical equipment is available, permanent normocalcemia following reoperations in pHPT is more frequently achieved than it used to be. The best option to avoid reoperations and associated complications is a successful initial intervention by an experienced surgeon. However, reoperations should always be performed by an experienced surgeon.

[Zollinger-Ellison syndrome]. / Zollinger-Ellison-Syndrom Das gewandelte Verständnis der Chirurgie.

The preoperative localization of gastrinomas often fails despite all modern imaging methods. Therefore, after biochemical confirmation of the diagnosis and exclusion of diffuse metastases, a meticulous surgical exploration including intraoperative ultrasound (IOUS) and duodenal exploration after duodenotomy should be performed. The experienced surgeon will be able to identify more than 90% of the primary tumors. Depending on the localization, excision of the tumor in the duodenal wall or enucleation from the pancreatic head should be performed. If the tumor is localized in the tail of the pancreas, distal pancreatectomy is the treatment of choice. Complete resection of the tumor is the only curative approach for the patients. For MEN-1 gastrinomas a spleen-preserving distal pancreatectomy with enucleation of tumors of the pancreatic head and duodenotomy with excision of duodenal gastrinomas should be performed. If the source of gastrin secretion can be regionalized to the pancreatic head by a preoperative SASI angiography, a pylorus-preserving partial pancreaticoduodenectomy might be the treatment of choice.

[A virtual reality simulator for objective assessment of surgeons' laparoscopic skill]. / Laparoskopiesimulator Abbildung der manuellen Geschicklichkeit in der laparoskopischen Chirurgie.

BACKGROUND: The aim of this study was to validate computed virtual reality simulation as a tool to assess laparoscopic skills and to establish whether the simulator allows differentiating between surgeons with different laparoscopic experience. METHODS: 27 physicians at the surgical department of the University of Marburg, Germany, with different experience in laparoscopic surgery were divided into three groups: experienced (group I), intermediate (group II), and novices (group III). Following a brief introduction to the virtual reality simulator (LapSim), each participant performed twice a training program consisting of seven tasks (examinations I and II). RESULTS: Comparison of experienced surgeons with less experienced laparoscopic physicians showed a significant (P<0.05) superiority of group I at examinations I and II in most exercises. The groups' difference was more obvious in examination II, since the technique was new for all participants during examination I. Tasks of low complexity in virtual reality such as camera navigation, which are performed by young, not yet responsible surgeons in real surgery, did not show significantly different results between the three groups. CONCLUSION: Differences in laparoscopic experience can be visualised with a virtual reality simulator, and thus a simulator is helpful for assessing surgeons' laparoscopic skills.

Transforming growth factor-beta 1 is a negative regulator for differentiated thyroid cancer: studies of growth, migration, invasion, and adhesion of cultured follicular and papillary thyroid cancer cell lines.

Invasion and metastasis may be caused by the escape of tumor cells from the negative control of growth factors. We analyzed the effects of transforming growth factor-beta 1 (TGF beta 1) on growth, migration, invasion, and adhesion in three follicular thyroid cancer cell lines (FTC133, primary; FTC236, lymph node metastasis; FTC238, lung metastasis) from one patient and in a papillary line (PTC-UC3). Cell growth was measured by dimethylthiazol-diphenyltetrazolium bromide assays, and migration (basal or epidermal growth factor stimulated) was determined by the ability of cells to penetrate 8-microns pore membranes that were covered with Matrigel for invasion assays. Moreover, we studied tumor cell adhesion to collagen type IV, fibronectin, and laminin. TGF beta 1 inhibited growth in FTC (FTC133, by 31%; FTC236, 15%; FTC238, 17%; P < 0.008), but not in PTC. Migration was inhibited in all cell lines. TGF beta 1 inhibited epidermal growth factor-stimulated migration of FTC133 by 43% vs. 29% without epidermal growth factor (P < 0.03). TGF beta 1 also inhibited invasion (FTC133, 32%; FTC236, 18%; FTC238, 16%; PTC-UC3, 32%; P < 0.02). All cell lines adhered preferably to collagen type IV and fibronectin. TGF beta 1 enhanced adhesion. Again, these effects were less pronounced in the FTC metastases. In conclusion, TGF beta 1 inhibits the growth, migration, and invasion of thyroid cancer cells in vitro. It enhances adhesion to components of the extracellular matrix. Metastatic thyroid tumors may be less responsive to the negative regulation of TGF beta 1.

A unique allogenic model of metastatic pheochromocytoma: PC12 rat pheochromocytoma xenografts to nude mice and establishment of metastases-derived PC12 variants.

Local invasion and metastatic spread to distant sites are major causes of death in patients with malignant pheochromocytoma. Since appropriate in vivo models do not exist, little is known about the underlying mechanisms of tumor growth and invasion. We, therefore, developed an animal model of malignant pheochromocytoma and established organotropic metastatic variants of PC12 rat pheochromocytoma cells. PC12 cells were established as xenografts to BALB/c NCR-NU mice. Subsequent to development of tumors or metastases, primary cultures from local tumors, metastases to lymph nodes, lungs and liver were established. These were subcultured in vitro and reinjected for up to five successive in vivo/in vitro cycles. Xenografted PC12 cells grew tumors with a doubling time of 6.78 +/- 0.58 days during log phase of tumor growth, killing hosts within 5-12 weeks depending on the experimental conditions. Tumors reproducibly metastasized to lymph nodes and the lung. Spontaneous metastases to the liver were not observed, but were achieved by intrasplenic injection of parent PC12 cells. In vitro, the metastatic cell lines displayed striking differences in morphology, overall growth patterns and nutritional requirements as well as binding to purified extracellular matrix proteins compared to the parent cell line. In vivo, the metastatic variants showed marked enhancement of metastatic ability. This is the first report of PC12 rat pheochromocytoma cells to exhibit the malignant phenotype in vivo. We also established variant PC12 cell lines that preferentially metastasized to specific sites and that had acquired different in vitro behavior and ability to metastasize. This unique model system should be useful for further studies relating to the invasion and metastases of pheochromocytoma and may prove valuable for investigations of novel antineoplastic therapies in vitro and in vivo.

Aberrations of growth factor control in metastatic follicular thyroid cancer in vitro.

The aggressiveness of follicular thyroid cancer (FTC) varies widely, and metastasis is the primary cause of death. Uncontrolled proliferation of cancer cells may be associated with loss of growth factor control. We investigated the effects of stimulating (epidermal growth factor [EGF]; thyreotropin [TSH] in low concentrations) and inhibiting growth factors (transforming growth factor beta 1 [TGF beta 1]; TSH in high concentrations) on invasion and growth of FTC cell lines from the thyroid tumor (FTC133) and from the lymph node (FTC236) and lung (FTC238) metastases of the same patient. Invasion-penetration through an 8 microns pore membrane, covered by Matrigel (basement membrane)-and growth were measured using the MTT-method. EGF (10 ng/ml) and TSH in low concentrations (1 mU/ml) stimulated invasion and growth of all FTC cell lines, but the amplitude of stimulation differed significantly. The parental cell line FTC133 was considerably more responsive to growth factor stimulation than the metastatic clones. Invasion of FTC133 was enhanced by 42% (EGF; p < 0.02) and 21% (TSH; p < 0.01), invasion of FTC236 by 8% (EGF; p < 0.02) and 8% (TSH; p < 0.01), and invasion of FTC238 by 9% (EGF; p < 0.02) and 8% (TSH; p < 0.01). Conversely, invasion and growth of FTC133 were significantly more inhibited by TGF beta 1 (10 ng/ml) and supraphysiologic concentrations of TSH (100 mU/ml) than the cell lines from the lymph node and lung metastases. At day 7, invasion of FTC133 was inhibited by 32% (TGF beta 1; p < 0.02) and 21% (TSH; p < 0.01), invasion of FTC236 by 18% (TGF beta 1; p < 0.02) and 11% (TSH; p < 0.01), and invasion of FTC238 by 16% (TGF beta 1; p < 0.02) and 12% (TSH; p < 0.01). Moreover, we analyzed growth factor independence in minimally supplemented or unsupplemented medium. Growth, but no invasion was evident when cells were cultured completely unsupplemented over 7 days. These results suggest that metastatic FTCs may have developed by escaping from the normal control of TSH and other growth factors.

Octreotide: effective treatment for hyperparathyroidism? A prospective, randomized, controlled clinical trial.

BACKGROUND: Recent studies suggest a role for somatostatin in the medical treatment of hyperparathyroidism. In a prospective, randomized, controlled, triple blinded clinical trial in patients with primary or secondary hyperparathyroidism, we evaluated the response of biochemical parameters relevant in hyperparathyroidism to the somatostatin analog octreotide. METHODS: Forty patients each with primary or secondary hyperparathyroidism were studied. Among other parameters, serum calcium and serum phosphate, parathyroid hormone, calcitonin, osteocalcin, and octreotide were assessed before and repeatedly for 4 hours after a single intravenous application of 200 micrograms octreotide or placebo. Subsequent to operation, which was performed on all patients, somatostatin-receptor autoradiography of parathyroid tissue was performed. RESULTS: After administration of octreotide, which resulted in an increase of plasma levels to pharmacologic levels, no significant changes in any of the biochemical parameters investigated for were observed. Multivariate analysis did not identify patient subpopulations that responded to either drug or placebo (p > 0.05). Forty-five percent of patients receiving octreotide reported side effects: Parathyroid tissue samples of patients with primary or secondary hyperparathyroidism were negative for somatostatin-receptor expression. CONCLUSIONS: Octreotide has no discernible effect on biochemical parameters of patients with primary or secondary hyperparathyroidism. Absence of somatostatin receptors, together with lack of octreotide effects, suggests that somatostatin is not effective in the medical therapy of hyperparathyroidism.

Establishment of a highly differentiated thyroid cancer cell line of Hürthle cell origin.

Hürthle cell carcinomas (HCC) of the thyroid are a variant of follicular thyroid tumors. In contrast to follicular thyroid carcinoma, HCC rarely take up radioiodine and frequently metastasize to the lymph nodes. Histologically they are indistinguishable from Hürthle cell adenomas except for evidence of invasion and metastasis. How these carcinomas develop and why they behave differently than other follicular tumors is not known. Although some differentiated thyroid cancer cell lines exist, none are from Hürthle cell tumors. We have established a well-differentiated thyroid cancer cell line from a metastasis of a HCC, designated XTC.UC1. In vitro, XTC cells display epitheloid morphology, grow with a population doubling time of 4.3 +/- 0.3 days, migrate, and invade through reconstituted basement membranes. The cells are immunoreactive for and release thyroglobulin, respond to thyrotropin (TSH) with increase of intracellular cyclic adenosine monophosphate (cAMP), proliferation, and invasion of reconstituted basement membrane, thus exhibiting characteristics of well-differentiated thyroid carcinoma. In vivo, xenografted XTC cells grow with a doubling time of 9.8 +/- 0.8 days. Tumors spontaneously metastasize to the lymph nodes and less frequently to the lungs and the liver. The cells retained their differentiated function in vivo as assessed by human thyroglobulin (hTG) secretion and immunohistochemistry. This is a first report of the establishment of a unique, highly differentiated thyroid carcinoma cell line derived from an HCC. Based on the ability to invade through reconstituted basement membrane in vitro and the potential to metastasize in vivo, this cell line may provide a unique model to study invasion and metastazation of well-differentiated thyroid cancer.

In vitro and in vivo angiogenesis in PC12 pheochromocytoma cells is mediated by vascular endothelial growth factor.

Angiogenesis, the formation of new blood vessels from existing vascular endothelium, is essential for tumor growth. Vascular endothelial growth factor (VEGF) is an endotheliumspecific mitogen and regulator of angiogenesis. Angiogenesis has been associated to the malignant phenotype of pheochromocytomas and is readily observed in experimental pheochromocytomas. Although VEGF gene expression has already been demonstrated in the rat PC12 cell line, the detailed mechanisms of action are not known. We have, therefore, studied angiogenesis in the rat PC12 pheochromocytoma cell line in vitro and in vivo. VEGF gene expression and accumulation of VEGF protein in cytoplasm and conditioned medium of PC12 cells was found. Conditioned medium from PC12 cells significantly increased proliferation of VEGF-dependent endothelial cells from human umbilical veins, and this effect reversed upon addition of a neutralizing anti-VEGF antibody. Dexamethasone and nerve growth factor (NGF) increased VEGF mRNA expression and accumulation of VEGF protein of PC12 subclones with established metastatic activity in vivo. PC12 cells xenotransplanted to nude mice had marked VEGF expression and induced host angiogenesis, confirmed by the presence of CD34-positive endothelial cells in the experimental PC12 tumors. When NGF-primed PC12 cells were immobilized in Matrigel supplemented with rising concentrations of the growth factor and xenotransplanted, increasing NGF resulted in tumors with smaller areas of necrosis and increased vital tumor volume. These results suggest that VEGF is a mediator of angiogenesis in the PC12 pheochromocytoma cell line, and that dexamethasone and NGF affect VEGF expression. Our data further suggest that NGF may contribute to angiogenesis in experimental pheochromocytoma.

Isotransplantation of microencapsulated parathyroid tissue in rats.

Permanent hypoparathyroidism is one of the most difficult of all endocrine disorders to treat medically. While autotransplantation of parathyroid tissue is clinically established, allotransplantation without immunosuppression is still at the level of animal experiments. Although persons affected by hypoparathyroidism are facing a clearly reduced quality of life, hypoparathyroidism rarely is a life threatening condition. Therefore, systemic immunosuppression for recipients of allotransplants is not justified. A conceptional alternative would be protecting the tissue to be transplanted from the immunologic response by coating it with a semipermeable membrane (microencapsulation). In 1994, we succeeded in iso-, allo- and xenotransplantation of microencapsulated parathyroid tissue in an animal model. Unfortunately, prior to the first clinical use, further analysis of the coating substance (alginate) demonstrated that it has mitogenic properties. Here, we report on the first successful transplantation of microencapsulated parathyroid tissue using a purified, non-mitogenic alginate which is suitable for clinical use.