Ioannis Christakis

Minimally invasive parathyroidectomy in patients with previous neck surgery.

OBJECTIVEPrevious neck surgery (PNS) in patients with primary hyperparathyroidism (PHP) is considered as a contraindication for minimally invasive parathyroidectomy (MIP). The purpose of our study was to determine the effectiveness of MIP in such patients.DESIGNFrom January 2003 to June 2011, 380 patients with PHP were treated in our department; 42 had had previous neck surgery. Twenty-seven (27/42) were selected to have MIP; the remaining 15 patients had traditional neck explorations. Selection criteria for MIP were unilateral single or two gland disease localized preoperatively with at least two imaging techniques and patient’s informed consent. Imaging studies included high resolution neck ultrasound and sestamibi scan in the majority, and CT scan, selective venous sampling and MRI in seven patients. The type of operation done included unilateral approach under local anesthesia (UALA) (22 cases) with one conversion to general anesthesia and minimally invasive parathyroidectomy under general anesthesia (MIPG) (5 cases).RESULTSTwenty-six of the 27 patients became normocalcemic after the operation. The patient with persistent hypercalcemia underwent successful parathyroidectomy 8 months later via mesothoracoscopy, since the parathyroid gland was localized correctly but was beyond access via neck. A single adenoma was found in 21 cases and hyperplasia in six. There were no conversions to traditional exploration and no postoperative complications. Mean duration of the procedure and length of stay were similar to MIP in patients without PNS. Mean follow-up of 40 months (4–89 months) did not reveal any recurrence.CONCLUSIONThese results illustrate that MIP is a valuable option in selected patients with PHP and PNS associated with no morbidity (0%), high biochemical cure rate (96.3% in this series) and rapid recovery, while it also substantially lowers the cost of the procedure. Preoperative localization with two or more agreeing imaging techniques eliminates the need for intraoperative sestamibi or qPTH test.

Minimally invasive techniques for giant parathyroid tumours; An oxymoron?

Aim-BackgroundOn rare occasions, a parathyroid tumour weighing more than 3.5 grams is removed; such a tumour is referred to as a “giant” tumour. We report 47 cases of giant parathyroid tumours, the second largest published series so far.Patients-MethodsWe retrospectively reviewed all prospectively collected data of operations performed for primary hyperparathyroidism over a period of 16 years. The duration of the operation, length of hospital stay, conversions and complications rates were recorded prospectively.ResultsGiant parathyroid tumours were removed in 47 out of the 457 cases (10.28%). The mean weight of the parathyroid tumour in the group receiving minimally invasive surgery was 8.9 grams (3.5–20 grams) with a mean size of 5.4 cm (1.7–7 cm). Twenty-seven patients had a minimally invasive parathyroidectomy and 20 underwent a classical procedure. There were no complications or recurrences. Mean hospital stay was approximately 20 hours (19–23 hours), and mean follow-up was 33 months (3–70 months).ConclusionThese results illustrate that minimally invasive techniques are a valuable option in selected patients with giant parathyroid tumours. Surgical expertise in the endocrine field cannot be overemphasized.

Measuring the Pharmacokinetic Properties of Drugs with a Novel Surgical Rat Model

ABSTRACT Purpose/aim of the study: The pharmacokinetic (PK) parameters in animal models can help optimize novel candidate drugs prior to human trials. However, due to the complexity of pharmacokinetic experiments, their use is limited in academia. We present a novel surgical rat model for investigation of pharmacokinetic parameters and its use in an anti-obesity drug development program. Materials and methods: The model uses anesthetized male Wistar rats, a jugular, a femoral catheter, and an insulin pump for peptide infusion. The following pharmacokinetic parameters were measured: metabolic clearance rate (MCR), half-life, and volume of distribution (Vd). Glucagon-like peptide 1 (GLP-1), glucagon (GCG), and exendin-4 (Ex-4) were used to validate the model. The pharmacokinetic parameters of anti-obesity drug candidates X1, X2, and X3 were measured. Results: GLP-1 had a significantly higher MCR (83.9 ± 14.1 mL/min/kg) compared to GCG (40.7 ± 14.3 mL/min/kg) and Ex-4 (10.1 ± 2.5 mL/min/kg) (p < .01 and p < .001 respectively). Ex-4 had a statistically significant longer half-life (35.1 ± 7.4 min) compared to both GCG (3.2 ± 1.7 min) and GLP-1 (1.2 ± 0.4 min) (p < .01 for both GCG and GLP-1). Ex-4 had a statistically significant higher volume of distribution (429.7 ± 164.9 mL/kg) compared to both GCG (146.8 ± 49.6 mL/kg) and GLP-1 (149.7 ± 53.5 mL/kg) (p < .01 for both GCG and GLP-1). Peptide X3 had a statistically significant longer half-life (21.3 ± 3.5 min) compared to both X1 (3.9 ± 0.4 min) and X2 (16.1 ± 2.8 min) (p < .001 for both X1 and X2). Conclusions: We present an affordable and easily accessible platform for the measurement of PK parameters of peptides. This novel surgical rat model produces consistent and reproducible results while minimizing animal use.

Metastasis to the thyroid gland from a tonsil squamous cell carcinoma

We present a case of rare metastasis of tonsil squamous cell carcinoma to the thyroid gland, after 2 years of treatment without recurrence at the primary site. The patient had incidental finding of a nodule in the left lobe of the thyroid gland during a screening scan for his previous tonsil squamous cell carcinoma that was treated surgically 2 years ago. The patient was completely asymptomatic with normal thyroid function tests. After further investigations and discussion in the MDT meeting, the patient underwent left thyroid lobectomy as a definitive treatment for his thyroid metastasis.

Proglucagon-Derived Peptides Do Not Significantly Affect Acute Exocrine Pancreas in Rats

Objectives Reports have suggested a link between treatment with glucagon-like peptide 1 (GLP-1) analogs and an increased risk of pancreatitis. Oxyntomodulin, a dual agonist of both GLP-1 and glucagon receptors, is currently being investigated as a potential antiobesity therapy, but little is known about its pancreatic safety. The aim of the study was to investigate the acute effect of oxyntomodulin and other proglucagon-derived peptides on the rat exocrine pancreas. Methods Glucagon-like peptide 1, oxyntomodulin, glucagon, and exendin-4 were infused into anesthetized rats to measure plasma amylase concentration changes. In addition, the effect of each peptide on both amylase release and proliferation in rat pancreatic acinar (AR42J) and primary isolated ductal cells was determined. Results Plasma amylase did not increase postpeptide infusion, compared with vehicle and cholecystokinin; however, oxyntomodulin inhibited plasma amylase when coadministered with cholecystokinin. None of the peptides caused a significant increase in proliferation rate or amylase secretion from acinar and ductal cells. Conclusions The investigated peptides do not have an acute effect on the exocrine pancreas with regard to proliferation and plasma amylase, when administered individually. Oxyntomodulin seems to be a potent inhibitor of amylase release, potentially making it a safer antiobesity agent regarding pancreatitis, compared with GLP-1 agonists.

Do flow volume loops alter surgical management in patients with a goitre

Flow volume loops (FVLs) are considered part of the workup of patients with thyroid enlargement presenting to the endocrinology clinic. They are used to detect upper airway obstruction (UAO) secondary to tracheal compression (TC) from a goitre. Surgical assessment in contrast tends to focus on clinical evaluation supplemented when required by imaging. The aim of this study was to investigate whether FVLs influence the decision to operate in patients with a goitre.

Non-endocrine tumors causing endocrine syndromes: a brief review

In the early decades of the 20th century it was established that some non neuro-endocrine malignant tumors and their metastasis, were secreting substances with biologic properties and causing clinical syndromes similar to the ones caused by naturally occurring hormones. The most known syndromes are caused by substances mimicking the biologic properties of ACTH, erythropoietin, insulin and PTH. Many theories have been postulated in an attempt to explain the synthesis process of hormone mimetic substances. Ectopic secretion of ACTH syndrome comprises 10%-20% of all cases presenting with Cushings syndrome. The clinical picture manifests in a variable way. The increased plasma levels of cortisol in these cases, cause symptoms distinct from the ones of true Cushings syndrome. In general these patients have an ominous prognosis. Survival is limited to 6-12 months and is attributed to hypercortisolemia that is known to increase the risk of metastasis. Hypercalcemia syndrome from ectopic secretion of hypercalcemic factors is a severe complication of cancer patients with an incidence of 5-10%. Increased serum calcium is caused either by the osteolytic metastasis of malignant tumors or by their secretions. The clinical picture caused is similar to the findings of primary hyperparathyroidism. Treatment options in case of acute and severe hypercalcemia in patients with malignancy are limited. The endocrine syndromes produced by non-endocrine tumors not only affect patients quality of life but also occasionally cause severe complications and can disrupt surgical or medical treatment of the primary tumor. Searching for the occurrence of such syndromes demands a high index of suspicion. This paper brings the spotlight back to the clinical syndromes of hypercortisolemia and hypercalcemia caused by ectopic ACTH and hypercalcemic factors respectively, re-iterating the need for early diagnosis and prompt management in such cases.