MEDULLARY THYROID CANCER THAT STAINS NEGATIVE FOR CA 19-9 HAS DECREASED METASTATIC POTENTIAL.

OBJECTIVE: Presently, no clinical tools are available to diagnose the metastatic potential of medullary thyroid cancer (MTC) at disease presentation. Surveillance with calcitonin (Ct) and carcinoembryonic antigen (CEA) is currently recommended for the observation and diagnosis of metastatic disease after initial treatment of MTC. Recently, carbohydrate antigen (CA)19-9 staining has been associated with aggressive forms of MTC and metastatic spread. This pilot study explored whether positive CA19-9 staining of MTC tissue is associated with its metastatic potential. METHODS: Sixteen cases of MTC were identified, and tissue specimens were immunostained for CA 19-9 and other MTC tumor markers. Clinical information about patients' MTC was collected through a retrospective chart review. RESULTS: Overall, 63% of the specimens stained positive for CA19-9. The median size of positively staining specimens was 2.6 cm (interquartile range [IQR] 1.2-3.2) compared to 0.7 cm (0.5-1.2) in negatively staining MTC specimens (P = .04). All specimens from patients diagnosed with stage IV MTC stained positive for CA19-9, compared to only 40% of cases that were classified as stages I to III (P = .03). Furthermore, 100% of the primary specimens that were documented to have metastatic spread stained positive for CA19-9. The sensitivity for ruling out stage IV MTC based on negative staining for CA 19-9 was 100%. CONCLUSION: Based on these results, we conclude that negative staining of MTC for CA19-9 may be associated with its decreased metastatic potential.

Potent humanin analog increases glucose-stimulated insulin secretion through enhanced metabolism in the ß cell.

Humanin (HN) is a 24-aa polypeptide that offers protection from Alzheimer's disease and myocardial infarction, increases insulin sensitivity, improves survival of ß cells, and delays onset of diabetes. Here we examined the acute effects of HN on insulin secretion and potential mechanisms through which they are mediated. Effects of a potent HN analog, HNGF6A, on glucose-stimulated insulin secretion (GSIS) were assessed in vivo and in isolated pancreatic islets and cultured murine ß cell line (ßTC3) in vitro. Sprague-Dawley rats (3 mo old) that received HNGF6A required a significantly higher glucose infusion rate and demonstrated higher insulin levels during hyperglycemic clamps compared to saline controls. In vitro, compared to scrambled peptide controls, HNGF6A increased GSIS in isolated islets from both normal and diabetic mice as well as in ßTC3 cells. Effects of HNGF6A on GSIS were dose dependent, K-ATP channel independent, and associated with enhanced glucose metabolism. These findings demonstrate that HNGF6A increases GSIS in whole animals, from isolated islets and from cells in culture, which suggests a direct effect on the ß cell. The glucose-dependent effects on insulin secretion along with the established effects on insulin action suggest potential for HN and its analogs in the treatment of diabetes.

Pancreatic beta-cell overexpression of the glucagon receptor gene results in enhanced beta-cell function and mass.

In addition to its primary role in regulating glucose production from the liver, glucagon has many other actions, reflected by the wide tissue distribution of the glucagon receptor (Gcgr). To investigate the role of glucagon in the regulation of insulin secretion and whole body glucose homeostasis in vivo, we generated mice overexpressing the Gcgr specifically on pancreatic beta-cells (RIP-Gcgr). In vivo and in vitro insulin secretion in response to glucagon and glucose was increased 1.7- to 3.9-fold in RIP-Gcgr mice compared with controls. Consistent with the observed increase in insulin release in response to glucagon and glucose, the glucose excursion resulting from both a glucagon challenge and intraperitoneal glucose tolerance test (IPGTT) was significantly reduced in RIP-Gcgr mice compared with controls. However, RIP-Gcgr mice display similar glucose responses to an insulin challenge. beta-Cell mass and pancreatic insulin content were also increased (20 and 50%, respectively) in RIP-Gcgr mice compared with controls. When fed a high-fat diet (HFD), both control and RIP-Gcgr mice developed similar degrees of obesity and insulin resistance. However, the severity of both fasting hyperglycemia and impaired glucose tolerance (IGT) were reduced in RIP-Gcgr mice compared with controls. Furthermore, the insulin response of RIP-Gcgr mice to an IPGTT was twice that of controls when fed the HFD. These data indicate that increased pancreatic beta-cell expression of the Gcgr increased insulin secretion, pancreatic insulin content, beta-cell mass, and, when mice were fed a HFD, partially protected against hyperglycemia and IGT.

EVOLVING ADRENAL DYSFUNCTION AFTER BILATERAL ADRENAL INFARCTION: A CASE REPORT.

OBJECTIVE: To describe a case of sequential bilateral adrenal infarction and hemorrhage resulting in an unusual pattern of adrenal function over time. METHODS: A 50-year-old male with autoimmune antiphospholipid syndrome (APS) presented to the emergency room with severe abdominal pain. Diagnostic studies performed included contrast-enhanced computerized tomographic (IV-CT) imaging of abdomen and pelvis, and laboratory assessment of the hypothalamic-pituitary-adrenal axis. RESULTS: IV-CT of abdomen and pelvis on day 1 showed acute left adrenal gland infarction; cortisol level was 19.9 µg/dL and serum sodium was 133 mEq/L. The patient subsequently developed hyponatremia and hypotension. Repeat IV-CT of abdomen and pelvis on day 3 showed hemorrhagic conversion of the left infarcted adrenal gland and a new right adrenal gland infarction. Cosyntropin stimulation test (CST) confirmed primary glucocorticoid insufficiency. Plasma renin activity and the serum aldosterone level were within normal limits with normokalemia. At 7-month follow-up, CST demonstrated cortisol and aldosterone deficiency. CONCLUSION: Adrenal infarction is a rare complication of APS but is the most common endocrine complication. Evidence of bilateral adrenal infarction on imaging does not predict the type of adrenal dysfunction that might ensue, as demonstrated in this case. Thorough evaluation of glucocorticoid, mineralocorticoid, and androgen deficiency should be conducted both at the time of the event and in follow-up.

Hepatitis C virus infection is associated with insulin resistance among older adults with or at risk of HIV infection.

OBJECTIVES: To determine the associations of hepatitis C virus (HCV) infection with insulin resistance and abnormal glucose tolerance in a cohort of older adults with or at risk of HIV infection. DESIGN: A cross-sectional study of 267 HIV-infected and 179 at-risk-uninfected adults without a history of diabetes mellitus. METHODS: HCV antibody assays and RNA levels were performed to assess HCV status. Antiretroviral use, family history of diabetes, sedentary behavior, and sociodemographic data were obtained using standardized interviews. Fasting insulin levels and oral glucose tolerance tests were performed to assess two outcomes, the homeostasis model assessment of insulin resistance and abnormal glucose tolerance [impaired glucose tolerance (IGT) or diabetes]. RESULTS: Of 446 participants, 265 (59%) were HCV seropositive; of these, 199 (75%) had detectable HCV-RNA levels. Insulin resistance was greater among HCV-seropositive compared with seronegative participants, adjusting for body mass index, Hispanic ethnicity, age greater than 55 years, sedentary behavior (watching television > 4 h/day), HIV status, HAART, and protease inhibitor (PI) use. Ninety-eight participants (22%) had abnormal glucose tolerance (69 with IGT and 29 with diabetes). Among HIV-infected participants, 25% were on non-PI HAART and 52% were on PI HAART, but HAART and PI use were not associated with insulin resistance or abnormal glucose tolerance. Among obese participants, abnormal glucose tolerance was more common in HCV-seropositive than seronegative individuals, whereas among non-obese participants there was no association. CONCLUSION: The potential impact of HCV co-infection and obesity on glucose metabolism should be recognized in clinical care, and addressed in future research studies of HIV-infected individuals.

Disorders of glucose metabolism among HIV-infected women.

BACKGROUND: Abnormal glucose metabolism in HIV-infected patients has largely been attributed to the use of protease inhibitors. However, most studies of glucose metabolism in HIV-infected patients have focused on men or have lacked appropriate control groups. METHODS: We assessed the factors associated with previously diagnosed diabetes among 620 middle-aged women with or at risk for HIV infection. For a subset of 221 women without previously diagnosed diabetes, we performed an oral glucose tolerance test (OGTT) to measure glucose and insulin levels, and we assessed factors associated with abnormal glucose tolerance, insulin resistance, and insulin secretion. RESULTS: Thirteen percent of the women in the present study had previously diagnosed diabetes. Among women without previously diagnosed diabetes who underwent an OGTT, 6% had previously undiagnosed diabetes, and 12% had impaired glucose tolerance (IGT). According to multivariate analysis, factors that were associated with previously diagnosed diabetes included current methadone treatment, body mass index of > or =25, family history of diabetes, and physical inactivity. Factors that were independently associated with an abnormal result of an OGTT (i.e., a result consistent with IGT or diabetes) included age > or =50 years, family history of diabetes, physical inactivity, and a high number of pack-years of smoking. Factors independently associated with insulin resistance included waist circumference, Hispanic ethnicity, physical inactivity, and, among HIV-infected women, use of HAART that did not include protease inhibitors. Factors associated with lower levels of insulin secretion included current opiate use (i.e., methadone or heroin) and older age. CONCLUSIONS: Abnormal glucose metabolism is highly prevalent among middle-aged women with or at risk for HIV infection, particularly women who use opiates. Screening for diabetes in the HIV primary care setting should occur for women who have classic risk factors for diabetes, rather than solely for women who are taking PIs. Interventions that target modifiable risk factors, including obesity and physical inactivity, are also warranted.

Metastatic medullary thyroid cancer presenting with elevated levels of CA 19-9 and CA 125.

BACKGROUND: Calcitonin and carcinoembryonic antigen (CEA) are established markers of medullary thyroid cancer (MTC), used in the diagnosis and monitoring of disease and its progression. In clinical practice, various other tumor markers are utilized in the follow-up of different malignancies, although their utility has not been well described in MTC. CA 19-9 antigen, routinely used in the monitoring of pancreatic cancer, also has been detected in the tissue of approximately 6% of MTCs. However, its presence has never been reported in the serum of these patients. Elevation of CA 125 antigen, utilized as a tumor marker for ovarian cancer, has never been reported in MTC. We report a novel finding of metastatic MTC presenting with elevated CA 19-9 and CA 125 serum levels, with concurrent tissue staining for these antigens. SUMMARY: A 56-year-old woman with multiple endocrine neoplasia 2B syndrome, post subtotal thyroidectomy for MTC in childhood, presented with extensive metastatic spread of MTC to the lungs and liver, 47 years after the original diagnosis. The patient's calcitonin level decreased from 2950 to 261 pg/mL (reference range: <20 pg/mL) over a 20-year period. The serum CEA level was elevated at 6800 ng/mL (reference range: <5.1 ng/mL). Because of a concern for an alternate malignancy, serum CA 19-9 and CA 125 tumor markers were measured and found to be significantly elevated, at 39,334 U/mL (reference range: <35.1 U/mL) and 96.2 U/mL (reference range: 7-41 U/mL), respectively. Immunostaining of the metastatic MTC tissue showed patchy staining for calcitonin, strongly positive staining for CEA and CA 19-9, and weakly positive staining for CA 125. CONCLUSION: Drawing from experience with CA 19-9 and CA 125 tumor markers in other malignancies, we propose that they may be associated with aggressive forms of MTC with significant metastatic potential.

Switching of mesodermal and endodermal properties in hTERT-modified and expanded fetal human pancreatic progenitor cells.

INTRODUCTION: The ability to expand organ-specific stem/progenitor cells is critical for translational applications, although uncertainties often arise in identifying the lineage of expanded cells. Therefore, superior insights into lineage maintenance mechanisms will be helpful for cell/gene therapy. METHODS: We studied epithelial cells isolated from fetal human pancreas to assess their proliferation potential, changes in lineage markers during culture, and capacity for generating insulin-expressing beta cells. Cells were isolated by immunomagnetic sorting for epithelial cell adhesion molecule (EpCAM), and characterized for islet-associated transcription factors, hormones, and ductal markers. Further studies were performed after modification of cells with the catalytic subunit of human telomerase reverse transcriptase (hTERT). RESULTS: Fetal pancreatic progenitor cells efficiently formed primary cultures, although their replication capacity was limited. This was overcome by introduction and expression of hTERT with a retroviral vector, which greatly enhanced cellular replication in vitro. However, we found that during culture hTERT-modified pancreatic progenitor cells switched their phenotype with gain of additional mesodermal properties. This phenotypic switching was inhibited when a pancreas-duodenal homeobox (Pdx)-1 transgene was expressed in hTERT-modified cells with a lentiviral vector, along with inductive signaling through activin A and serum deprivation. This restored endocrine properties of hTERT-modified cells in vitro. Moreover, transplantation studies in immunodeficient mice verified the capacity of these cells for expressing insulin in vivo. CONCLUSIONS: Limited replication capacity of pancreatic endocrine progenitor cells was overcome by the hTERT mechanism, which should facilitate further studies of such cells, although mechanisms regulating switches between meso-endodermal fates of expanded cells will need to be controlled for developing specific applications. The availability of hTERT-expanded fetal pancreatic endocrine progenitor cells will be helpful for studying and recapitulating stage-specific beta lineage advancement in pluripotent stem cells.

Reversal of hyperglycemia in mice by using human expandable insulin-producing cells differentiated from fetal liver progenitor cells.

Beta-cell replacement is considered to be the most promising approach for treatment of type 1 diabetes. Its application on a large scale is hindered by a shortage of cells for transplantation. Activation of insulin expression, storage, and regulated secretion in stem/progenitor cells offers novel ways to overcome this shortage. We explored whether fetal human progenitor liver cells (FH) could be induced to differentiate into insulin-producing cells after expression of the pancreatic duodenal homeobox 1 (Pdx1) gene, which is a key regulator of pancreatic development and insulin expression in beta cells. FH cells possess a considerable replication capacity, and this was further extended by introduction of the gene for the catalytic subunit of human telomerase. Immortalized FH cells expressing Pdx1 activated multiple beta-cell genes, produced and stored considerable amounts of insulin, and released insulin in a regulated manner in response to glucose. When transplanted into hyperglycemic immunodeficient mice, the cells restored and maintained euglycemia for prolonged periods. Quantitation of human C-peptide in the mouse serum confirmed that the glycemia was normalized by the transplanted human cells. This approach offers the potential of a novel source of cells for transplantation into patients with type 1 diabetes.