Anomalous ion channeling in AlInN/GaN bilayers: determination of the strain state

Monte Carlo simulations of anomalous ion channeling in near-lattice-matched AlInN/GaN bilayers allow an accurate determination of the strain state of AlInN by Rutherford backscattering or channeling. Although these strain estimates agree well with x-ray diffraction (XRD) results, XRD composition estimates are shown to have limited accuracy, due to a possible deviation from Vegard's law, which we quantify for this alloy. As the InN fraction increases from 13% to 19%, the strain in AlInN films changes from tensile to compressive with lattice matching predicted to occur at [InN] = 17.1%.

Das familiäre Nebenschilddrüsenkarzinom

In contrast to primary hyperparathyroidism, parathyroid carcinoma is a rare disease. In patients with hyperparathyroidism jaw tumor (HPT-JT) syndrome, caused by germline mutations in HRPT2, the development of parathyroid carcinoma is estimated to be 10-15%. This review summarizes the clinical and molecular genetic data of about 100 patients in the literature and three of our own cases. Unfortunately, osteofibromas, which might enable timely diagnosis of HPT-JT syndrome, occur in only about 30% of patients; about 80% have uniglandular disease. Based on the current data, a general recommendation to perform prophylactic parathyroidectomy cannot be given. However, thorough screening of patients at risk is mandatory. Of note in patients thought to have sporadic parathyroid carcinoma, germline HRPT2 mutations are found in up to 20%. Hence, any patient with parathyroid carcinoma should undergo HRPT2 mutation analysis.

TAp73/Delta Np73 influences apoptotic response, chemosensitivity and prognosis in hepatocellular carcinoma

We investigated the mechanisms by which TAp73 beta and dominant-negative p73 (Delta Np73) regulate apoptosis. TAp73 beta transactivated the CD95 gene via the p53-binding site in the first intron. In addition, TAp73 beta induced expression of proapoptotic Bcl-2 family members and led to apoptosis via the mitochondrial pathway. Endogenous TAp73 was upregulated in response to DNA damage by chemotherapeutic drugs. On the contrary, DeltaNp73 conferred resistance to chemotherapy. Inhibition of CD95 gene transactivation was one mechanism by which DeltaNp73 functionally inactivated the tumor suppressor action of p53 and TAp73 beta. Concomitantly, DeltaNp73 inhibited apoptosis emanating from mitochondria. Thus, DeltaNp73 expression in tumors selects against both the death receptor and the mitochondrial apoptosis activity of TAp73 beta. The importance of these data is evidenced by our finding that upregulation of DeltaNp73 in hepatocellular carcinoma patients correlates with reduced survival. Our data indicate that Delta Np73 is an important gene in hepatocarcinogenesis and a relevant prognostic factor.

Ambulante und kurzzeitstation�re Schilddr�sen- und Nebenschilddr�senchirurgie

Outpatient or short-stay thyroid and parathyroid surgery is still uncommon in Germany. Although a substantial number of these operations are performed with low morbidity, nearly zero mortality, and short operation time, some potentially lethal complications, especially postoperative hemorrhage, are strong arguments against liberal shortening of hospital stay. Symptomatic hematomas after thyroid and parathyroid surgery are observed in about 1-2% of cases. They frequently occur during the first 8 h after operation (40%). However, two thirds of these major complications occur later, about 20% of them more than 24 h postoperatively. Therefore, an outpatient procedure cannot be generally recommended. Short-stay (<23 h, overnight) thyroid and parathyroid surgery may be attractive, but this concept requires clear release-criteria and professional outpatient structures. Compared to general anesthesia, local and regional anesthesia did not emerge as helpful to shorten hospital stay. Also, prophylactic calcium supplementation is not recommended to enhance early hospital discharge after bilateral thyroid or parathyroid surgery.

High diagnostic accuracy of adrenal core biopsy: results of the German and Austrian adrenal network multicenter trial in 220 consecutive patients

Incidentally detected adrenal tumors are a common finding during abdominal ultrasonography, computed tomography, and magnetic resonance imaging. Although most of these lesions are benign adenomas, adrenocortical carcinomas and metastases constitute 5% to 10% of all tumors. Adrenal biopsy may be helpful, but its diagnostic value is controversial and disputed, and prospective studies have not yet been performed. Therefore, the diagnostic accuracy of adrenal core biopsy was evaluated in a prospective multicenter study involving 8 surgical centers in Germany and Austria. A total of 220 biopsies from surgical specimens of the adrenal gland were punctured in an ex vivo approach and processed for pathohistologic diagnosis using paraffin sections, routine staining, and immunohistochemistry (keratin KL1, vimentin, S100 protein, chromogranin A, synaptophysin, neuron-specific enolase, D11, MiB-1, and p53 protein). The evaluating pathologist was blinded for clinical data from the patients. A total of 89 adrenal adenomas (40.5%), 22 adrenal carcinomas (10.0%), 55 pheochromocytomas (25.0%), 15 metastases (6.8%), 16 adrenal hyperplasias (7.2%), and 23 other tumors (10.5%) were studied. Nine cases were excluded due to incomplete data (n = 2) or insufficient biopsy specimen (n = 7). In the remaining 211 tumors, compared with the final diagnoses of the surgical specimen, bioptic diagnoses were absolutely correct in 76.8% of the cases, nearly correct in 13.2% of the cases, and incorrect in 10% of the cases. Pheochromocytomas were correctly diagnosed in 96% of the cases, cortical adenomas were correctly or nearly correctly reported in 91% of the cases, cortical carcinomas were correctly or nearly correctly reported in 76% of the cases, and metastases were correctly or nearly correctly reported in 77% of the cases. Of the 39 malignant lesions, only 4 were misclassified, 2 as benign and 2 as possibly malignant. This resulted in an overall sensitivity for malignancy of 94.6% and specificity of 95.3%. Our findings suggest that adrenal core biopsy is a useful method for identifying and classifying adrenal tumorous lesions if sufficient biopsy specimens can be obtained. However, in clinical practice it remains to be shown whether the benefits of biopsy outweigh the risks of the procedure.

Color Doppler sonography of the lateral thoracic (breast-feeding) arteries: a new approach to the diagnosis of breast disease?

OBJECTIVE

The main arteries to the breast are the lateral thoracic artery and to a lesser extent the internal thoracic artery. In this prospective open diagnostic study involving 94 women, we compared the intraindividual differences of Doppler indices in the lateral thoracic (breast-feeding) artery of breasts affected by cancer with those unaffected by disease.

METHODS

Sixty-seven consecutive patients were recruited from an outpatient unit for breast surgery and 27 volunteers were studied who were known to be without any breast disease (controls). In each patient we attempted to obtain Doppler indices from the lateral thoracic artery of both breasts. The difference in Doppler indices in each individual was assessed and statistical analysis was performed to assess whether these differences were significantly altered in women with cancer compared to healthy women.

RESULTS

Lateral thoracic arteries could be visualized in 88% of the study population. Significantly lower values for pulsatility and resistance indices and systolic/diastolic ratios were obtained in the lateral thoracic arteries of breasts affected by cancer as compared to the contralateral breasts (1.73 +/- 0.39 vs. 2.05 +/- 0.47, P = 0.003; 0.78 +/- 0.06 vs. 0.84 +/- 0.06, P < 0.0001; 4.71 +/- 1.24 vs. 6.75 +/- 3.38, P = 0.0008, respectively). Using the intraindividual difference of pulsatility index, resistance index and systolic/diastolic ratio to screen for malignancy, sensitivities for breast cancer of 78%, 85% and 83%, respectively, were achieved. Depending on the cut-off level, specificity reached 94%.

CONCLUSION

The intraindividual difference in Doppler indices in women with breast cancer may be a useful test for the diagnosis of breast lesions.

Minimally invasive video-assisted parathyroidectomy: multiinstitutional study

Unilateral and minimally invasive parathyroidectomies with endoscopic and video-assisted technique have been introduced. Most of these procedures utilize preoperative localization and intraoperative monitoring of parathyroid hormone. There are only a few reports on these procedures. The objective of this study was to evaluate video-assisted parathyroidectomy (MIVAP) for surgery in patients with primary hyperparathyroidism (pHPT). From February 1997 to June 1999 a series of 123 consecutive patients with pHPT at four surgical centers were evaluated. The patients' ages ranged from 18 to 77 years (median 50 years). Preoperatively, sestamibi scintigraphy and ultrasonography for localization were performed for all patients. Selection criteria for a MIVAP procedure excluded patients with negative localization, suspicion of multiglandular disease (MGD) or thyroid malignancy, a large thyroid mass, and prior surgery or irradiation to the neck. MIVAP was performed with a 1.5 cm suprasternal incision; the operation was then done through this incision with a 30 degree 5 mm endoscope and microsurgical instruments with brief CO2 insufflation for adenoma identification. We then proceeded with an open technique through the small incision under video-assistance. Intraoperative monitoring of intact parathyroid hormone (iPTH) assays was used in all patients. Among the 123 patients in whom MIVAP was attempted, the procedure was accomplished in 109 (89%). Conversion to conventional cervicotomy was required in 14 (11%) patients because of failed localization, failure of the iPTH level to fall appropriately, or technical problems. There was no persistent or recurrent HPT during the 3 to 12-month follow-up. Oral calcium replacement for symptomatic hypocalcemia postoperatively was given in 7 (6%) cases. A unilateral transient laryngeal nerve palsy, resolving within 6 months postoperatively, occurred in two (2%) patients. The median hospital stay was 1.5 days (range 0.5-5.0 days). This study showed the feasibility of MIVAP as an alternative surgical treatment for pHPT in a selected group of patients. Further studies are necessary to evaluate the efficacy and rationale of MIVAP compared to other techniques for parathyroidectomy in pHPT patients.

Differential neutrophil traffic in gut and lung after scald injury

Neutrophil recruitment to the lung after thermal injury has been reported by various laboratories. Changes in neutrophil populations in the gut and lung have not been examined simultaneously after burn injury. Mice aged 8 to 10 weeks were anesthetized and subjected to 15% topical scald injury. Animals were sacrificed at 30 minutes and 1, 2, 4, 8, 16, and 32 hours after injury with harvesting of terminal ileum and lung for myeloperoxidase (MPO) assay. Lungs were evaluated after bronchoalveolar lavage and lavage of the vascular bed to remove neutrophils in these compartments. Myeloperoxidase activity was compared between groups of sham-injured and burned animals. Although pulmonary neutrophil recruitment was obvious after scald burn; in the ileum, burned animals showed diminished MPO activity. Histology and bronchoalveolar lavage revealed no evidence of gross organ injury apart from obvious changes in cellular content in the lung. Thermal injury is associated with differential neutrophil movement in the lung and the gut in this model. Pulmonary neutrophil recruitment is confirmed, whereas the gut seems to lose neutrophils as indicated by diminished MPO activity in the initial hours after dorsal scald injury.

Differential regulation of two thiolase genes from Clostridium acetobutylicum DSM 792

Thiolase of Clostridium acetobutylicum is an important enzyme involved in both, acid and solvent fermentation. Two thiolase genes (thlA and thIB) have been cloned and sequenced from Clostridium acetobutylicum DSM 792, showing high homology to each other and to thiolases of PHA-synthesizing bacteria. The thlA gene is identical to the gene already cloned and sequenced from strain ATCC 824 (Stim-Herndon et al., 1995, Gene 154: 81-85). Using primer extension and S1 nuclease analysis a transcriptional start site was identified 102 bp upstream of the thlA start codon. This site was preceded by a region that exhibits high similarity to the sigma70 consensus promoter sequences of Gram-positive and -negative bacteria. Regulation of thlA and thlB was studied at the transcriptional level to elucidate the specific function of each gene. Non-radioactive primer extension analysis using fluorescein-labelled oligonucleotides and Northern blot analysis revealed high levels of thlA transcripts in acid- and solvent-producing cells. During an induced shift of a continuous culture from acid to solvent formation, the transcript level transiently decreased to a minimum, 3 to 7 h after induction. The thlA transcript length is about 1.4 kb, indicating a monocistronic organisation, whereas genetic organization and reverse transcription (RT)-PCR analysis indicated that thlB forms an operon with two other adjacent genes, thlR and thlC. Transcription and regulation of the thlB operon was studied using RTPCR and showed a very low expression in acid- and solvent-producing cells. Heterologously expressed clostridial ThlB showed high thiolase activity in Escherichia coli. The N-terminal part of ThlR possesses a potential helix-turn-helix motif and shows significant homology to regulatory proteins belonging to the TetR/AcrR family of transcriptional regulators. ThlR possibly acts as a transcriptional repressor of thlB operon expression. The data provide strong evidence that ThlA is involved in the metabolism of both acid and solvent formation, whereas the physiological function of ThlB has yet to be elucidated.

Concept of and preliminary trial protocol for adjuvant treatment of mediastinitis with immunoglobulins after cardiac surgery (ATMI): response to comments and criticism

During the consensus-based process of protocol development external experts were invited to comment on a proposal for a trial protocol on adjuvant immunotreatment of patients with wound infection after median sternotomy (ATMI). Controversies and arguments can be divided into five main areas: 1) rationale and objectives; 2) criteria for patient selection; 3) adjuvant treatment; 4) measures of efficacy; and 5) course and timetable of the study. We present and summarise the experts comments and criticism as well as the result of the final discussion of the study group with respect to these areas.

[A new standard method for experimental for measuring cement coat strength in endoprosthesis implantation]

The distribution of bone cement around an endoprosthesis influences its stability over the long term. We have developed a new method for the experimental measurement of the cement mantle thickness of an endoprosthesis. The use of this computer-aided procedure is described in a hip prosthesis. Transverse sections of a human femur containing a cemented stem were prepared, recorded with a CCD camera and the images fed into a computer. The image-processing software differentiated the metal and bone cement on the basis of the different colours. Radial lines were drawn from the calculated centre of gravity of the stem, and the cement thickness was measured automatically along these lines. In our experiment, the accuracy of the method was 0.2 mm. This method of measuring the thickness of the cement mantle is accurate, rapid and practical.

Axillary lymph nodes in breast cancer: is size related to metastatic involvement?

Usually when using imaging procedures, such as axillary mammography or ultrasonography, a cutoff level of 5 mm for lymph node size is postulated to be not only the limit of lymph node visibility but also a sign of metastatic involvement. The aim of this study was to evaluate whether this assumption, used as a basic hypothesis in many reports, is true. A series of 72 axillary specimens from 71 breast carcinoma patients operated at the university hospital of Vienna were analyzed. A comparison of histologically noninvolved axillary specimens with those showing metastatic involvement revealed that the two groups did not differ significantly according to the number or size of lymph nodes per axilla. For lymph nodes <5 mm the probability of being metastatically involved was still 10%. Enlarged lymph nodes (5-20 mm) had a slightly higher risk of being malignant (20%). In contrast, the probability of metastatic involvement for lymph nodes >20 mm was only 40%. We suggest that many reports dealing with the prediction of malignancy in axillary lymph nodes may have used misleading basic assumptions, so the results of these studies must be viewed critically.

Unilateral open and minimally invasive procedures for primary hyperparathyroidism: a review of selective approaches

The currently established procedure for surgical treatment of primary hyperparathyroidism is bilateral exploration and visualization of all four glands to identify an adenoma and exclude multiglandular disease. With the development of improved preoperative localization imaging of the parathyroids using high-resolution ultrasonography and sestamibi scintigraphy, on the one hand, and perioperative control of surgical success with a rapid parathyroid hormone assay on the other, unilateral and minimally invasive techniques have become feasible. For patients with unequivocal localization in preoperative sestamibi scintigraphy and high-resolution ultrasonography of the parathyroid adenoma in probable single-gland disease, the unilateral and minimally invasive parathyroidectomy present a therapeutic option. Perioperative rapid parathyroid hormone assays, although costly, offer immediate supervision of adenoma extirpation and differentiation of single- and multiglandular disease. These methods demonstrate advantages with favorable cosmetic results and lower reported rate of postoperative hypoparathyroidism. These methods are already being practiced in some places under local anesthesia and in an ambulatory setting. This contribution provides an introduction and overview of the currently practiced unilateral and minimally invasive techniques of parathyroidectomy for primary hyperparathyroidism, discussing indications, advantages and disadvantages, and technical differences in the practiced methods.

Dendrimers: relationship between structure and biocompatibility in vitro, and preliminary studies on the biodistribution of 125I-labelled polyamidoamine dendrimers in vivo

Dendrimers are highly branched macromolecules of low polydispersity that provide many exciting opportunities for design of novel drug-carriers, gene delivery systems and imaging agents. They hold promise in tissue targeting applications, controlled drug release and moreover, their interesting nanoscopic architecture might allow easier passage across biological barriers by transcytosis. However, from the vast array of structures currently emerging from synthetic chemistry it is essential to design molecules that have real potential for in vivo biological use. Here, polyamidoamine (PAMAM, Starburst), poly(propyleneimine) with either diaminobutane or diaminoethane as core, and poly(ethylene oxide) (PEO) grafted carbosilane (CSi-PEO) dendrimers were used to study systematically the effect of dendrimer generation and surface functionality on biological properties in vitro. Generally, dendrimers bearing -NH(2) termini displayed concentration- and in the case of PAMAM dendrimers generation-dependent haemolysis, and changes in red cell morphology were observed after 1 h even at low concentrations (10 microg/ml). At concentrations below 1 mg/ml CSi-PEO dendrimers and those dendrimers with carboxylate (COONa) terminal groups were neither haemolytic nor cytotoxic towards a panel of cell lines in vitro. In general, cationic dendrimers were cytotoxic (72 h incubation), displaying IC(50) values=50-300 microg/ml dependent on dendrimer-type, cell-type and generation. Preliminary studies with polyether dendrimers prepared by the convergent route showed that dendrimers with carboxylate and malonate surfaces were not haemolytic at 1 h, but after 24 h, unlike anionic PAMAM dendrimers they were lytic. Cationic 125I-labelled PAMAM dendrimers (gen 3 and 4) administered intravenously (i.v.) to Wistar rats ( approximately 10 microg/ml) were cleared rapidly from the circulation (<2% recovered dose in blood at 1 h). Anionic PAMAM dendrimers (gen 2.5, 3.5 and 5.5) showed longer circulation times ( approximately 20-40% recovered dose in blood at 1 h) with generation-dependent clearance rates; lower generations circulated longer. For both anionic and cationic species blood levels at 1 h correlated with the extent of liver capture observed (30-90% recovered dose at 1 h). 125I-Labelled PAMAM dendrimers injected intraperitoneally were transferred to the bloodstream within an hour and their subsequent biodistribution mirrored that seen following i.v. injection. Inherent toxicity would suggest it unlikely that higher generation cationic dendrimers will be suitable for parenteral administration, especially if they are to be used at a high dose. In addition it is clear that dendrimer structure must also be carefully tailored to avoid rapid hepatic uptake if targeting elsewhere (e.g. tumour targeting) is a primary objective.

Chlorpromazine modulates cytokine expression in the liver and lung after burn injury and endotoxemia

BACKGROUND

Previous data from our laboratory have demonstrated that alterations in cytokine production occur in the lung and liver as the result of a two-hit model of injury, i.e., burn with subsequent endotoxin administration. The purpose of this study was to determine whether the phenothiazine derivative chlorpromazine would alter cytokine production in a sequential model of injury.

METHODS

By using a sublethal burn/endotoxemia model, B2D6F1 mice (n = 40) were assigned to two groups and subjected to a 15% full-thickness burn. Three days after burn injury, one group (BURN/ETX) received 2.5 mg/kg Escherichia coli endotoxin intraperitoneally, and the other group (CPZ) received 4 mg/kg chlorpromazine 1 hour before the administration of 2.5 mg/kg E. coli endotoxin intraperitoneally. At selected time points, the animals were killed and lung and liver were removed and processed for protein and total RNA. Northern blots and enzyme-linked immunosorbent assays were used to assess the production of tumor necrosis factor-alpha, macrophage inflammatory protein-1alpha, and interleukin-10.

RESULTS

Chlorpromazine significantly reduced tumor necrosis factor-alpha mRNA and protein expression in the liver. Macrophage inflammatory protein-1alpha mRNA was reduced by chlorpromazine in both liver and lung. Interleukin-10 production was not altered by chlorpromazine.

CONCLUSION

The reduction of tumor necrosis factor-alpha and macrophage inflammatory protein-1alpha by chlorpromazine in the liver and lungs may have potential as a pharmaceutical agent that may dampen the inflammatory response in a model of sequential injury.

Borderless teleradiology with CHILI

Teleradiology is one of the most evolved areas of telemedicine, but one of the basic problems which remains unsolved concerns system compatibility. The DICOM (Digital Imaging and Communications in Medicine) standard is a prerequisite, but it is not sufficient in all aspects. Examples of other currently open issues are security and cooperative work in synchronous teleconferences. Users without a DICOM radiological workstation would benefit from the ability to join a teleradiology network without any special tools. Drawbacks of many teleradiology systems are that they are monolithic in their software design and cannot be adapted to the actual user's environment. Existing radiological systems currently cannot be extended with additional software components. Consequently, every new application usually needs a new workstation with a different look and feel, which must be connected and integrated into the existing infrastructure. This paper introduces the second generation teleradiology system CHILI. The system has been designed to match both the teleradiology requirements of the American College of Radiology (ACR), and the functionality and usability needs of the users. The experiences of software developers and teleradiology users who participated in the first years of the clinical use of CHILI's predecessor MEDICUS have been integrated into a new design. The system has been designed as a component-based architecture. The most powerful communication protocol for data exchange and teleconferencing is the CHILI protocol, which includes a strong data security concept. The system offers, in addition to its own secure protocol, several different communication Methods: DICOM, classic e-mail, Remote Copy functions (RCP), File Transfer Protocol (FTP), the internet protocols HTTP (HyperText Transfer Protocol) and HTTPS (HyperText Transfer Protocol Secure),and CD-ROMs for off-line communication. These transfer METHODS allow the user to send images to nearly anyone with a computer and a network. The drawbacks of the non-CHILI protocols are that teleconferences are not possible, and that the user must take reasonable precautions for data privacy and security. The CHILI PlugIn mechanism enables the users or third parties to extend the system capabilities by adding powerful image postprocessing functions or interfaces to other information systems. Suitable PlugIns can be either existing programs, or dedicated applications programmed with interfaces to the CHILI components. The developer may freely choose programming languages and interface toolkits. The CHILI architecture is a powerful and flexible environment for Picture Archiving and Communications Systems (PACS)and teleradiology. More than 40 systems are currently running in clinical routine in Germany. More than 300,000 images have been distributed among the communication partners in the last two years. Feedback and suggestions from the users influenced the system architecture by a great extent. The proposed and implemented system has been optimized to be as platform independent, open, and secure as possible.

Minimally invasive video-assisted parathyroidectomy--selective approach to localized single gland adenoma

BACKGROUND

The valid operative standard for primary hyperparathyroidism (pHPT) consists of cervicotomy and presentation of all parathyroid glands. This operative technique features the macroscopic identification of the responsible adenoma. It also has the advantage of detecting multiglandular disease. The increasing sensitivity of preoperative localization methods and the possibility of intra-operative measurement of parathyroid hormone prepared the way for minimally invasive procedures.

METHODS

All patients with pHPT were examined by cervical sonography and sestamibi scintigraphy of the parathyroid glands. Patients eligible for the described procedure had to comply to the following inclusion criteria: biochemical evidence of pHPT, localization of one unequivocally enlarged parathyroid gland on two corresponding imaging results; no former surgery or radiation to the neck; no multinodular goiter; no suspected carcinoma of the thyroid; and no secondary or recurrent hyperparathyroidism. We used an operative technique first described by Miccoli in 1997. Before preparation and at 2, 10 and 15 min after exstirpation of the parathyroid adenoma, peripheral blood was drawn. The operation was terminated when a 50% decrease of preoperative PTH levels was reached.

RESULTS

During a 12-month period (1 December 1997 to 30 November 1998), 13 patients with pHPT of a total of 59 patients (22%) with hyperparathyroidism (pHPT and sHPT) were operated on employing this minimally invasive procedure. In three patients, the operative technique had to be converted to the conventional procedure due to superior adenomas in two cases and a dorsoesophageal adenoma in one case. The procedure could thus be successfully completed in ten patients. The overall failure rate was zero in all patients with regard to the underlying disease. There was one temporary, recurrent laryngeal-nerve palsy. The mean overall length of the hospital stay was 3 days.

CONCLUSION

The minimally invasive video-assisted parathyroidectomy for localized single-gland adenoma is a new and attractive surgical therapy option for primary hyperparathyroidism due to improved patient comfort, shortened length of hospital stay and favorable cosmetic results. This may lead to one-day surgery and, therefore, to a reduction of overall costs.

Diagnostic strategies and surgical procedures in persistent or recurrent primary hyperparathyroidism

The incidence of persistent or recurrent primary hyperparathyroidism reported in the literature lies between 1 and 10%. The main causes are represented by atypical locations or incorrect diagnosis of primary parathyroid hyperplasia. Since primary parathyroidectomy by an experienced surgeon has a success rate of 95%, there is no need for extended imaging studies prior to initial bilateral exploration. After confirming diagnosis of persistent or recurrent hyperparathyroidism exact localization studies are necessary. The most important procedures are ultrasonography, magnetic resonance imaging, technetium Tc99m sestamibi scintigraphy with a combined sensitivity of approximately 90%. In case of negative imaging results selective venous catheterization before reoperation can be performed. Reoperation by an experienced surgeon will be successful in 95% of cases.