Involvement of human monogenic cardiomyopathy genes in experimental polygenic cardiac hypertrophy.

Hypertrophic cardiomyopathy thickens heart muscles, reducing functionality and increasing risk of cardiac disease and morbidity. Genetic factors are involved, but their contribution is poorly understood. We used the hypertrophic heart rat (HHR), a unique normotensive polygenic model of cardiac hypertrophy and heart failure, to investigate the role of genes associated with monogenic human cardiomyopathy. We selected 42 genes involved in monogenic human cardiomyopathies to study: 1) DNA variants, by sequencing the whole genome of 13-wk-old HHR and age-matched normal heart rat (NHR), its genetic control strain; 2) mRNA expression, by targeted RNA-sequencing in left ventricles of HHR and NHR at 5 ages (2 days old and 4, 13, 33, and 50 wk old) compared with human idiopathic dilated cardiomyopathy data; and 3) microRNA expression, with rat microRNA microarrays in left ventricles of 2-day-old HHR and age-matched NHR. We also investigated experimentally validated microRNA-mRNA interactions. Whole-genome sequencing revealed unique variants mostly located in noncoding regions of HHR and NHR. We found 29 genes differentially expressed in at least 1 age. Genes encoding desmoglein 2 ( Dsg2) and transthyretin ( Ttr) were significantly differentially expressed at all ages in the HHR, but only Ttr was also differentially expressed in human idiopathic cardiomyopathy. Lastly, only two microRNAs differentially expressed in the HHR were present in our comparison of validated microRNA-mRNA interactions. These two microRNAs interact with five of the genes studied. Our study shows that genes involved in monogenic forms of human cardiomyopathies may also influence polygenic forms of the disease.

Molecular mechanisms of cardiac pathology in diabetes - Experimental insights.

Diabetic cardiomyopathy is a distinct pathology independent of co-morbidities such as coronary artery disease and hypertension. Diminished glucose uptake due to impaired insulin signaling and decreased expression of glucose transporters is associated with a shift towards increased reliance on fatty acid oxidation and reduced cardiac efficiency in diabetic hearts. The cardiac metabolic profile in diabetes is influenced by disturbances in circulating glucose, insulin and fatty acids, and alterations in cardiomyocyte signaling. In this review, we focus on recent preclinical advances in understanding the molecular mechanisms of diabetic cardiomyopathy. Genetic manipulation of cardiomyocyte insulin signaling intermediates has demonstrated that partial cardiac functional rescue can be achieved by upregulation of the insulin signaling pathway in diabetic hearts. Inconsistent findings have been reported relating to the role of cardiac AMPK and ß-adrenergic signaling in diabetes, and systemic administration of agents targeting these pathways appear to elicit some cardiac benefit, but whether these effects are related to direct cardiac actions is uncertain. Overload of cardiomyocyte fuel storage is evident in the diabetic heart, with accumulation of glycogen and lipid droplets. Cardiac metabolic dysregulation in diabetes has been linked with oxidative stress and autophagy disturbance, which may lead to cell death induction, fibrotic 'backfill' and cardiac dysfunction. This review examines the weight of evidence relating to the molecular mechanisms of diabetic cardiomyopathy, with a particular focus on metabolic and signaling pathways. Areas of uncertainty in the field are highlighted and important knowledge gaps for further investigation are identified. This article is part of a Special issue entitled Cardiac adaptations to obesity, diabetes and insulin resistance, edited by Professors Jan F.C. Glatz, Jason R.B. Dyck and Christine Des Rosiers.

Medullary Thyroid Carcinoma: Survival Analysis and Evaluation of Mutation-Specific Immunohistochemistry in Detection of Sporadic Disease.

INTRODUCTION: Medullary thyroid cancer (MTC) is a rare tumour of neuroendocrine origin with a more aggressive profile than differentiated thyroid cancer. Familial cases of MTC are associated with RET mutations whilst RAS mutations appear to be a frequent finding in RET negative tumours. The aims of this study were to analyse survival outcomes in MTC and to evaluate the role of RAS immunohistochemistry in the identification of sporadic disease. MATERIALS AND METHODS: A retrospective cohort study of consecutive patients with MTC was undertaken. The primary outcome measures were overall survival and disease-free survival. Survival analysis was performed on the basis of sporadic and familial disease. Patients had routine RET testing using the capillary (Sanger) sequencing method. Histopathological MTC slides from 100 patients were tested for HRASQ61R, a common somatic RAS mutation in MTC, with mutation-specific immunohistochemistry (IHC). RESULTS: A total of 195 patients had surgical treatment of MTC in the period 1980 to 2016. There were 83 males and 112 females with a mean age of 53.0 years. A total of 39 (20%) patients had familial disease. Sporadic cases had a higher median pre-op calcitonin (969.5 vs. 257.5 pg/ml), greater mean primary tumour size (23.5 vs. 12.5 mm) and more distant metastases (12.8 vs. 10.3%). Multivariate analysis showed age (p = 0.005), Multiple Endocrine Neoplasia Type 2 (MEN2) status (p = 0.021) and distant metastasis (p = 0.002) to be significant independent predictors of survival. Significant independent predictors for disease-free survival were age (p = 0.015), MEN2 (p = 0.002), pre-op calcitonin (p = 0.033) and venous invasion (p = 0.001). The overall 5-year survival was 100% for familial MTC and 78% for sporadic MTC. The 10-year disease-free survival was 94% for familial MTC and 61% for sporadic cases. A total of 100 cases of MTC underwent mutation-specific IHC for HRASQ61R. Of these, 18 had confirmed MEN2. IHC had 100% specificity in excluding MEN2. Twelve (12%) of 100 patients stained positive for HRASQ61R mutation. CONCLUSION: In the era of genetic testing, RET status significantly influences disease-specific survival in MTC. Mutation-specific IHC for HRASQ61R may have a role in the identification of patients presenting with sporadic disease.

BRAF(V600E) Mutation is Associated with Decreased Disease-Free Survival in Papillary Thyroid Cancer.

BACKGROUND: The BRAF (V600E) mutation is a recognised molecular marker in papillary thyroid cancer (PTC), reported incidence from 30 to 80 %. BRAF(V600E) aberrantly activates the MAPK pathway, a central regulator of cell growth and proliferation. Previous studies have reported conflicting data regarding the impact of BRAF(V600E) on clinicopathological features of PTC. The study aims to determine whether BRAF(V600E) is useful as a prognostic biomarker in PTC. METHODS: A cohort study of patients undergoing surgery for PTC was undertaken. The primary outcome measure was disease-free survival. Secondary outcome measures were tumour size, nodal positivity and radioactive iodine ablation rate. All cases were re-examined to confirm PTC. Immunohistochemistry for BRAF(V600E) was performed on tissue microarrays. A single endocrine pathologist, blinded to clinicopathological data, interpreted staining. RESULTS: 496 patients with PTC were included, and 309 (62 %) were BRAF(V600E) positive. Tumour size was similar for BRAF(V600E)-positive and -negative tumours (21.3 vs. 23.2 mm, p = 0.23). BRAF(V600E)-positive patients were significantly older at first operation (mean age 45 versus 49 years, p = 0.003). BRAF(V600E)-positive PTCs had a higher rate of disease recurrence (12.9 vs. 5.6 %, p = 0.004), lymph node metastasis (44 vs. 29.4 %, p = 0.004) and extra-thyroidal extension (44 vs. 22 %, p < 0.001). Five-year disease-free survival was 89.6 % for BRAF(V600E) positive and 96.3 % for negative tumours, p < 0.001. There was no difference between groups for vascular invasion or multifocality. The mean follow-up was 57 months for both groups. CONCLUSION: BRAF(V600E) in PTC predicts an increased risk of lymph node metastasis, extra-thyroidal extension and reduced disease-free survival. It is an additional useful prognostic biomarker.

Long-term outcome after parathyroidectomy for lithium-induced hyperparathyroidism.

BACKGROUND: The accepted management of lithium-associated hyperparathyroidism (LiHPT) is open four-gland parathyroid exploration (OPTX). This approach has recently been the subject of controversy. A recent study has shown very high long-term recurrence rates after OPTX, whereas some have promoted unilateral focused parathyroidectomy as appropriate management. The aim was to evaluate long-term outcomes after surgery for LiHPT and to assess the accuracy of preoperative imaging. METHODS: This was a retrospective cohort study that comprised all patients undergoing initial surgery for LiHPT between 1990 and 2013. The cumulative recurrence rate was calculated by the Kaplan-Meier method. The sensitivity and specificity of sestamibi scintigraphy and ultrasound imaging for identification of single-gland versus multigland disease was investigated using intraoperative assessment as reference. RESULTS: Of 48 patients, 45 had OPTX and three underwent focused parathyroidectomy. Multiglandular disease was documented in 27 patients and 21 had a single adenoma. The median follow-up was 5·9 (range 0·3-22) years and 16 patients died during follow-up. The 10-year cumulative recurrence rate was 16 (95 per cent confidence interval 2 to 29) per cent. No permanent complications occurred after primary surgery for LiHPT. Twenty-four patients had at least one preoperative ultrasound or sestamibi scan. For concordant sestamibi scintigraphy and ultrasound imaging, the sensitivity and specificity for identifying single-gland versus multigland disease was five of nine and five of eight respectively. CONCLUSION: Surgery provided a safe and effective management option for patients with LiHPT in this series, with a long-term cure rate of well over 80 per cent.

Myocardial glycophagy - a specific glycogen handling response to metabolic stress is accentuated in the female heart.

Cardiac metabolic stress is a hallmark of many cardiac pathologies, including diabetes. Cardiac glycogen mis-handling is a frequent manifestation of various cardiopathologies. Diabetic females have a higher risk of heart disease than males, yet sex disparities in cardiac metabolic stress settings are not well understood. Oestrogen acts on key glycogen regulatory proteins. The goal of this study was to evaluate sex-specific metabolic stress-triggered cardiac glycogen handling responses. Male and female adult C57Bl/6J mice were fasted for 48h. Cardiac glycogen content, particle size, regulatory enzymes, signalling intermediates and autophagic processes were evaluated. Female hearts exhibited 51% lower basal glycogen content than males associated with lower AMP-activated-kinase (AMPK) activity (35% decrease in pAMPK:AMPK). With fasting, glycogen accumulated in female hearts linked with decreased particle size and upregulation of Akt and AMPK signalling, activation of glycogen synthase and inactivation of glycogen phosphorylase. Fasting did not alter glycogen content or regulatory proteins in male hearts. Expression of glycogen autophagy marker, starch-binding-protein-domain-1 (STBD1), was 63% lower in female hearts than males and increased by 69% with fasting in females only. Macro-autophagy markers, p62 and LC3BII:I ratio, increased with fasting in male and female hearts. This study identifies glycogen autophagy ('glycophagy') as a potentially important component of the response to cardiac metabolic stress. Glycogen autophagy occurs in association with a marked and selective accumulation of glycogen in the female myocardium. Our findings suggest that sex-specific differences in glycogen handling may have cardiopathologic consequences in various settings, including diabetic cardiomyopathy.

Ca2+-dependent proteolysis of junctophilin-1 and junctophilin-2 in skeletal and cardiac muscle.

Excessive increases in intracellular [Ca(2+)] in skeletal muscle fibres cause failure of excitation-contraction coupling by disrupting communication between the dihydropyridine receptors in the transverse tubular system and the Ca(2+) release channels (RyRs) in the sarcoplasmic reticulum (SR), but the exact mechanism is unknown. Previous work suggested a possible role of Ca(2+)-dependent proteolysis in this uncoupling process but found no proteolysis of the dihydropyridine receptors, RyRs or triadin. Junctophilin-1 (JP1; ∼90 kDa) stabilizes close apposition of the transverse tubular system and SR membranes in adult skeletal muscle; its C-terminal end is embedded in the SR and its N-terminal associates with the transverse tubular system membrane. Exposure of skeletal muscle homogenates to precisely set [Ca(2+)] revealed that JP1 undergoes Ca(2+)-dependent proteolysis over the physiological [Ca(2+)] range in tandem with autolytic activation of endogenous µ-calpain. Cleavage of JP1 occurs close to the C-terminal, yielding a ∼75 kDa diffusible fragment and a fixed ∼15 kDa fragment. Depolarization-induced force responses in rat skinned fibres were abolished following 1 min exposure to 40 µm Ca(2+), with accompanying loss of full-length JP1. Supraphysiological stimulation of rat skeletal muscle in vitro by repeated tetanic stimulation in 30 mm caffeine also produced marked proteolysis of JP1 (and not RyR1). In dystrophic mdx mice, JP1 proteolysis is seen in limb muscles at 4 and not at 10 weeks of age. Junctophilin-2 in cardiac and skeletal muscle also undergoes Ca(2+)-dependent proteolysis, and junctophilin-2 levels are reduced following cardiac ischaemia-reperfusion. Junctophilin proteolysis may contribute to skeletal muscle weakness and cardiac dysfunction in a range of circumstances.

Myocardial deformation imaging by 2D speckle tracking echocardiography for assessment of diastolic dysfunction in murine cardiopathology.

Diastolic dysfunction is increasingly identified as a key, early onset subclinical condition characterizing cardiopathologies of rising prevalence, including diabetic heart disease and heart failure with preserved ejection fraction (HFpEF). Diastolic dysfunction characterization has important prognostic value in management of disease outcomes. Validated tools for in vivo monitoring of diastolic function in rodent models of diabetes are required for progress in pre-clinical cardiology studies. 2D speckle tracking echocardiography has emerged as a powerful tool for evaluating cardiac wall deformation throughout the cardiac cycle. The aim of this study was to examine the applicability of 2D speckle tracking echocardiography for comprehensive global and regional assessment of diastolic function in a pre-clinical murine model of cardio-metabolic disease. Type 2 diabetes (T2D) was induced in C57Bl/6 male mice using a high fat high sugar dietary intervention for 20 weeks. Significant impairment in left ventricle peak diastolic strain rate was evident in longitudinal, radial and circumferential planes in T2D mice. Peak diastolic velocity was similarly impaired in the longitudinal and radial planes. Regional analysis of longitudinal peak diastolic strain rate revealed that the anterior free left ventricular wall is particularly susceptible to T2D-induced diastolic dysfunction. These findings provide a significant advance on characterization of diastolic dysfunction in a pre-clinical mouse model of cardiopathology and offer a comprehensive suite of benchmark values for future pre-clinical cardiology studies.

Reoperative surgery for bilateral multinodular goitre in the era of total thyroidectomy.

BACKGROUND: Total thyroidectomy, rather than bilateral subtotal thyroidectomy, is now accepted as the preferred management for bilateral benign multinodular goitre (BMNG) in order to reduce the need for reoperative surgery. The aim of this study was to examine whether this approach has had an impact on presentation for bilateral reoperative thyroid surgery. METHODS: This was a retrospective cohort study. The study group comprised patients presenting with recurrent BMNG who underwent bilateral reoperative thyroid surgery following previous bilateral subtotal or partial thyroidectomy. They were compared with patients undergoing unilateral reoperative thyroid surgery following previous lobectomy, and those undergoing primary total thyroidectomy for BMNG. RESULTS: Between 1 January 1987 and 31 December 2009, 12 354 consecutive thyroid procedures were undertaken. Among those with BMNG, primary total thyroidectomy was undertaken in 3298 patients, unilateral reoperative thyroidectomy in 337 and bilateral reoperative thyroidectomy in 191. Presentations of patients with recurrent BMNG declined gradually over the study period following the change in policy from subtotal to total thyroidectomy; only five patients (representing less than 0.5 per cent of all thyroid surgery) underwent bilateral reoperative surgery for BMNG in the last year of the study. Four of these patients had their initial operation before 1987 and in another unit, whereas the remaining patient initially had surgery overseas. CONCLUSION: The introduction of a policy of initial total thyroidectomy for bilateral BMNG has essentially eliminated the need for bilateral reoperative surgery for recurrent goitre.

Regulation of angiotensinogen by angiotensin II in mouse primary astrocyte cultures.

Astrocytes are the major source of angiotensinogen in the brain and play an important role in the brain renin-angiotensin system. Regulating brain angiotensinogen production alters blood pressure and fluid and electrolyte homeostasis. In turn, several physiological and pathological manipulations alter expression of angiotensinogen in brain. Surprisingly, little is known about the factors that regulate astrocytic expression of angiotensinogen. There is evidence that angiotensinogen production in both hepatocytes and cardiac myocytes can be positively regulated via the angiotensin type 1 receptor, but this effect has not yet been studied in astrocytes. Therefore, the aim of this project was to establish whether angiotensin II modulates angiotensinogen production in brain astrocytes. Primary astrocyte cultures, prepared from neonatal C57Bl6 mice, expressed angiotensinogen measured by immunocytochemistry and real-time PCR. Using a variety of approaches we were unable to identify angiotensin receptors on cultured astrocytes. Exposure of cultured astrocytes to angiotensin II also did not affect angiotensinogen expression. When astrocyte cultures were transduced with the angiotensin type 1A receptor, using adenoviral vectors, angiotensin II induced a robust down-regulation (91.4% ± 1.8%, p < 0.01, n = 4) of angiotensinogen gene expression. We conclude that receptors for angiotensin II are present in extremely low levels in astrocytes, and that this concurs with available data in vivo. The signaling pathways activated by the angiotensin type 1A receptor are negatively coupled to angiotensinogen expression and represent a powerful pathway for decreasing expression of this protein, potentially via signaling pathways coupled to Gα(q/11) .

Fructose Metabolism and Cardiac Metabolic Stress.

Cardiovascular disease is one of the leading causes of mortality in diabetes. High fructose consumption has been linked with the development of diabetes and cardiovascular disease. Serum and cardiac tissue fructose levels are elevated in diabetic patients, and cardiac production of fructose via the intracellular polyol pathway is upregulated. The question of whether direct myocardial fructose exposure and upregulated fructose metabolism have potential to induce cardiac fructose toxicity in metabolic stress settings arises. Unlike tightly-regulated glucose metabolism, fructose bypasses the rate-limiting glycolytic enzyme, phosphofructokinase, and proceeds through glycolysis in an unregulated manner. In vivo rodent studies have shown that high dietary fructose induces cardiac metabolic stress and functional disturbance. In vitro, studies have demonstrated that cardiomyocytes cultured in high fructose exhibit lipid accumulation, inflammation, hypertrophy and low viability. Intracellular fructose mediates post-translational modification of proteins, and this activity provides an important mechanistic pathway for fructose-related cardiomyocyte signaling and functional effect. Additionally, fructose has been shown to provide a fuel source for the stressed myocardium. Elucidating the mechanisms of fructose toxicity in the heart may have important implications for understanding cardiac pathology in metabolic stress settings.

Testosterone modulates cardiomyocyte Ca(2+) handling and contractile function.

The extent to which sex differences in cardiac function may be attributed to the direct myocardial influence of testosterone is unclear. In this study the effects of gonadal testosterone withdrawal (GDX) and replacement (GDX+T) in rats, on cardiomyocyte shortening and intracellular Ca(2+) handling was investigated (0.5 Hz, 25 oC). At all extracellular [Ca(2+)] tested (0.5-2.0 mM), the Ca(2+) transient amplitude was significantly reduced (by approximately 50 %) in myocytes of GDX rats two weeks post-gonadectomy. The time course of Ca(2+) transient decay was significantly prolonged in GDX myocytes (tau, 455+/-80 ms) compared with intact (279+/-23 ms) and GDX+T (277+/-19 ms). Maximum shortening of GDX myocytes was markedly reduced (by more than 60 %) and relaxation significantly delayed (by more than 35 %) compared with intact and GDX+T groups. Thus testosterone replacement completely reversed the cardiomyocyte hypocontractility induced by gonadectomy. These results provide direct evidence for a role of testosterone in regulating functional Ca(2+) handling and contractility in the heart.

Risk of needing completion thyroidectomy for low-risk papillary thyroid cancers treated by lobectomy.

Background: Low-risk differentiated thyroid cancers may, according to the American Thyroid Association (ATA) 2015 guidelines, be managed initially with lobectomy. However, definitive risk categorization requires pathological assessment of the specimen, resulting in completion thyroidectomy being recommended when discordance between preoperative and postoperative staging occurs. This study sought to establish the expected rate of completion thyroidectomy in patients with papillary thyroid cancer (PTC) treated by lobectomy. Methods: Patients with PTC treated over 5 years (2013-2017 inclusive) and meeting the ATA criteria for lobectomy were identified from the prospectively developed database of a high-volume, university department of endocrine surgery. Concordance between the ATA initial and final recommendation, and the putative rate of completion thyroidectomy were calculated. Multivariable analysis was used to assess preoperative factors as predictors of the need for total thyroidectomy. Results: Of 275 patients with PTC who met ATA preoperative criteria for lobectomy there was concordance between this and the final recommendation in 158 (57·5 per cent) and discordance in 117 (43·5 per cent). Most common reasons for discordance were: angioinvasion (30·8 per cent), local invasion (23·9 per cent) or both (20·5 per cent). Four patients (1·5 per cent) had permanent hypoparathyroidism. On multivariable analysis, age, sex, tumour size and family history did not independently predict the final treatment required. Conclusion: Although many patients may be treated adequately with lobectomy, just under half would require completion thyroidectomy. Further work is needed on preoperative risk stratification but, before this, total thyroidectomy remains the treatment of choice for low-risk 1-4-cm PTC in the hands of high-volume thyroid surgeons who can demonstrate low complication rates.

Functional and metabolic remodelling in GLUT4-deficient hearts confers hyper-responsiveness to substrate intervention.

Impaired glucose uptake is associated with both cardiac hypertrophy and contractile dysfunction, but whether there are common underlying mechanisms linking these conditions is yet to be determined. Using a 'gene dose' Cre-Lox GLUT4-deficient murine model, we examined the effect of suppressed glucose availability on global myocardial gene expression and glycolysis substrate bypass on the function of isolated perfused hearts. Performance of hearts from 22- to 60-week-old male GLUT4 knockout (KO, >95% reduction in GLUT4), GLUT4 knockdown (KD, 85% reduction in cardiac GLUT4) and C57Bl/6 wild-type (WT) controls was measured ex vivo in Langendorff mode perfusion. DNA microarray was used to profile mRNA expression differences between GLUT4-KO and GLUT4-KD hearts. At 22 weeks, GLUT4-KO hearts exhibited cardiac hypertrophy and impaired contractile function ex vivo, characterized by a 40% decrease in developed pressure. At 60 weeks, dysfunction was accentuated in GLUT4-KO hearts and evident in GLUT4-KD hearts. Exogenous pyruvate (5 mM) restored systolic pressure to a level equivalent to WT (GLUT4-KO, 176.8+/-13.2 mmHg vs. WT, 146.4+/-9.56 mmHg) in 22-week-old GLUT4-KO hearts but not in 60-week-old GLUT4-KO hearts. In GLUT4-KO, DNA microarray analysis detected downregulation of a number of genes centrally involved in mitochondrial oxidation and upregulation of other genes indicative of a shift to cytosolic beta-oxidation of long chain fatty acids. A direct link between cardiomyocyte GLUT4 deficiency, hypertrophy and contractile dysfunction is demonstrated. These data provide mechanistic insight into the myocardial metabolic adaptations associated with short and long-term insulin resistance and indicate a window of opportunity for substrate intervention and functional 'rescue'.

Minimally invasive parathyroidectomy and thyroidectomy--current concepts.

The introduction of various techniques for minimally invasive parathyroidectomy (MIP) and minimally invasive thyroid surgery (MITS) have changed both the conceptual and surgical approach to parathyroid disease and single thyroid nodules. Perceived advantages of minimally invasive surgery both among clinicians and patients, have been a major factor in the development of new surgical techniques, as well as refinement in preoperative localisation techniques. Worldwide the number of patients being operated on using MIP or MITS has steadily increased. At some major centres as many as 70% of patients with primary hyperparathyroidism have their operation using MIP. In this review we discuss the underlying pathology and investigative procedures, as well as the various techniques used, all of which now have excellent outcomes at a minimal cost and with minimal complications. Based on our own experience we recommend the use of a lateral focused mini-incision for both MIP and MIT since they both use standard equipment and standard dissection techniques familiar to all experienced endocrine surgeons.

Lymphadenectomy for papillary thyroid cancer: changes in practice over four decades.

AIMS: Lymphadenectomy in the management of papillary thyroid cancer (PTC) has evolved. The aim of this study was to examine the changing role of neck dissection as reflected in the practice of a large thyroid unit over four decades. METHODS: A retrospective cohort study of patients that underwent primary thyroid surgery for papillary cancer in a single unit in the period 1958-2002. Nine 5-year periods were considered and the data relevant to the treatment of the regional lymph nodes reviewed. RESULTS: Nine hundred patients with PTC underwent surgery between 1958 and 2002 of whom 32.7% underwent lymph node dissection (LND). The use of lymphadenectomy increased from 21.4% in 1958-1962 to 48.1% in 1998-2002 of which 84% underwent a selective lymph node dissection (SLND)-a dissection where the LND is determined by the extent of the disease encountered. The mean number of nodes removed during SLND was 12.6 (range 1-56) of which a mean of 3.1 (24.8%) (0-19) were involved by the disease. Cervical levels 6 and level 4 were those most frequently dissected. There was no statistically significant difference in the complication rates in patients undergoing neck dissection and those not. CONCLUSION: The four decade experience reflects a move away from modified radical neck dissection and cherry picking towards SLND. Growing evidence suggests that lymphadenopathy in adult PTC is an adverse prognostic factor. SLND, a lymphadenectomy tailored to the extent of the disease process, is the coherent treatment for PTC since it serves the dual purpose of staging as well as control of local disease. This can be achieved with little morbidity when performed in a specialist centre.

Sporadic and familial pheochromocytomas are associated with loss of at least two discrete intervals on chromosome 1p.

Pheochromocytomas are tumors of the adrenal medulla originating in the chromaffin cells derived from the neural crest. Ten % of these tumors are associated with the familial cancer syndromes multiple endocrine neoplasia type 2, von Hippel-Lindau disease (VHL), and rarely, neurofibromatosis type 1, in which germ-line mutations have been identified in RET, VHL, and NF1, respectively. In both the sporadic and familial form of pheochromocytoma, allelic loss at 1p, 3p, 17p, and 22q has been reported, yet the molecular pathogenesis of these tumors is largely unknown. Allelic loss at chromosome 1p has also been reported in other endocrine tumors, such as medullary thyroid cancer and tumors of the parathyroid gland, as well as in tumors of neural crest origin including neuroblastoma and malignant melanoma. In this study, we performed fine structure mapping of deletions at chromosome 1p in familial and sporadic pheochromocytomas to identify discrete regions likely housing tumor suppressor genes involved in the development of these tumors. Ten microsatellite markers spanning a region of approximately 70 cM (1pter to 1p34.3) were used to screen 20 pheochromocytomas from 19 unrelated patients for loss of heterozygosity (LOH). LOH was detected at five or more loci in 8 of 13 (61%) sporadic samples and at five or more loci in four of five (80%) tumor samples from patients with multiple endocrine neoplasia type 2. No LOH at 1p was detected in pheochromocytomas from two VHL patients. Analysis of the combined sporadic and familial tumor data suggested three possible regions of common somatic loss, designated as PC1 (D1S243 to D1S244), PC2 (D1S228 to D1S507), and PC3 (D1S507 toward the centromere). We propose that chromosome 1p may be the site of at least three putative tumor suppressor loci involved in the tumorigenesis of pheochromocytomas. At least one of these loci, PC2 spanning an interval of <3.8 cM, is likely to have a broader role in the development of endocrine malignancies.

Use of X-ray diffraction in study of human diabetic and aging collagen.

Extensive investigations of the solubility and fluorescence of collagen fibers in diabetes have revealed that there are significant changes in their physical properties. These changes are associated with increased cross-link formation. We used X-ray diffraction to study these changes in human extensor tendons at a molecular level in relation to both aging and diabetes. Our results indicate that diabetes induces significant alterations in the ultrastructure of collagen in the lateral packing of the molecules and the axial structure of the specimen. These changes can be induced in normal tendon by incubation in ribose and glucose-6-phosphate but are different from those associated with the normal process of aging.

The effect of salicylates on nonenzymatic glycosylation and thermal stability of collagen in diabetic rats.

The effects of glucose on the nonenzymatic glycosylation and thermal rupture time of rat tail collagen were examined by (1) in vitro incubation of collagen fibers in glucose and (2) in vivo in diabetic rats. In vitro, glucose caused a dose-dependent rise in both nonenzymatic glycosylation and thermal rupture time and there was a good correlation between these two parameters (r = 0.68, P less than 0.0001). Aspirin, a known inhibitor of nonenzymatic glycosylation, was effective in preventing the glucose-induced rise in nonenzymatic glycosylation and thermal rupture time when present at concentrations of 0.78, 1.56, and 3.12 mM. Sodium salicylate at concentrations of 1.56 and 3.12 mM was also effective. In vivo, the nonenzymatic glycosylation and thermal rupture time of collagen fibers were both increased by 2-3-fold in rats with streptozotocin-induced diabetes of 4 wk duration. Aspirin or sodium salicylate treatment for 4 wk (240 mg/kg/day) from the onset of diabetes was able to prevent the rise in thermal rupture time without affecting nonenzymatic glycosylation of collagen or glycosylated hemoglobin levels. Aspirin or sodium salicylate treatment did not have detectable effect on properties of collagen in normal rats. The in vitro findings are consistent with the hypothesis that nonenzymatic glycosylation leads to the increased thermal stability of collagen fibers. The significance of nonenzymatic glycosylation in vivo is less certain, as thermal rupture time can be altered independently. The action of aspirin and sodium salicylate in vivo suggests new therapeutic options in the prevention and treatment of diabetic complications.