Kohlenberg, Jacob

In this study, we propose two new mathematical models able to quantify glucagon secretion during a graded glucose infusion, in the presence and absence of amino acids. The models provide an index of α-cell responsivity, G 50 , i.e., the glucose increase required to suppress glucose secretion rate (GSR) by 50%. Results show that the presence of amino acids reduced α-cell responsivity to glucose.

CD36 is a microvascular endothelial cell (MVEC) receptor mediating angiostatic activity of TSP-1 and related proteins. We previously reported that lysophosphatidic acid (LPA), a biologically active lipid signaling mediator, inhibited MVEC CD36 transcription via PKD-1 signaling. Moreover, CD36 transcriptional repression abolished endothelial cell responses to TSP-1 in vitro and in vivo . We now show with luciferase transfection assays that LPA exposure significantly suppressed CD36 promoter activity in MVEC. Co-exposure to class II HDAC inhibitors SAHA or TSA reversed the inhibition of promoter activity and restored transcription. HDAC7 knockdown by shRNA also attenuated LPA-suppressed CD36 promoter activity and mRNA levels. Mechanistically, FoxO1 was found to directly interact with putative FoxO1 binding sites (FHRE) in proximal promoter in vitro by avidin-biotin-conjugated DNA-binding assay, and in vivo by chromatin IP assay. Furthermore, FHRE mutations significantly attenuated the promoter activity. Western blots and immunofluorescence microscopy showed increased nuclear accumulation of PKD-1, FoxO1 and HADC7 after MVEC were exposed to LPA. Co-IP of nuclear extracts showed a physical interaction of HDAC7 with FoxO1 that was attenuated with PKD-1 knockdown. These data demonstrate that HDAC7 modulation by LPA receptor/PKD-1 signaling pathway represses FoxO1-mediated CD36 transcriptional activity. Additionally, angiogenic transcription profiling of endothelial cells revealed significantly increased mRNA expression of 17 angiogenic genes in response to LPA, including ephrin B2 expression that was confirmed by Western Blots. Transduction of constitutively active PKD-1 (PKD-CA) into EC also increased ephrin B2 expression. Functionally, PKD-CA overexpression promoted branching morphogenesis of arterial endothelial cells in a three-dimensional spheroid assay. The data indicate that PKD-1 is a potent angiogenic and arteriogenic kinase in EC by down-regulating CD36 transcription and promoting arteriogenesis. PKD-1-FoxO1-CD36 signaling axis may have potential as an important target in cardiovascular ischemia and malignant tumors.

Abstract Introduction: Optimal initial antithyroid drugs (ATD) dosing may achieve rapid improvement in thyroid hormone levels while minimizing risk of adverse events. As ATD have become the most common first line therapy for the treatment of Graves’ disease (GD), we examined trends over time in initial ATD dosing, and the association between guideline-based ATD dosing with time to normalization of FT4 and frequency of adverse events. Methods: This is a single cohort retrospective study in Mayo Clinic, Rochester, MN. We identified adults (≥18 years old) diagnosed with new onset GD between January 1, 2002-December 31, 2019 treated with at least 14 days of ATD and with available initial follow up data within 3 months prior to a dose change. Propylthiouracil (PTU) doses were converted to Methimazole (MMI) equivalents at 10:1 ratio. Guideline concordant care was defined as initial ATD dosed based on 2016 American Thyroid Association guidelines (i.e. 5-10 mg for presenting FT4 between >1.7-2.55 ng/dL, 10-20 mg for 2.56-3.40 ng/dL, and 30-40 mg for 3.41 ng/dL and above). Based on the first follow up FT4 values, patients were grouped into categories of: normal range (FT4 0.9-1.7 ng/dL) and under treated (FT4 >1.7 ng/dL). Results: 398 patients were included; mean (SD) age was 49 years (16.6), and 75% were women. Mean initial (SD) Free T4 value was 3.9 ng/dL (2.8), with patients treated with ATD at mean (SD) starting dose of 21.9 mg (13.3) MMI equivalent. Over time there was a decrease in the starting ATD dose from 30 mg MMI equivalent in 2002-2004 to 20 mg in 2017-2019, despite steady presenting FT4 values (2.7 ng/dL in 2002-2005 and 3.1 ng/dL in 2017-2019). In the subset of 340 patients with overt hyperthyroidism, 181 (53%) received guideline concordant (GC) dosing. Patients receiving GC care had a higher initial FT4 (4.9 vs. 3.6 ng/dL, p=0.002), larger goiters (40 vs. 30 g, p<0.001) and higher initial ATD mean dose (SD) 25 mg (15.7) vs. 21.3 mg (9.9), p= 0.05. However at follow up (median 32 days vs 35 days respectively), both groups had similar proportion of patients with normal FT4 values (43% vs. 42%, p=0.79); undertreated patients (45% vs. 45%, p=0.99) and frequency of adverse events (4% vs. 6%, p=0.40). Conclusion: The initial dose of ATD for the treatment of GD has decreased over the past 2 decades. Most clinicians initiate ATD at a dose concordant to guidelines. Despite this, a significant proportion of patients have persistent hyperthyroidism on initial follow up. In light of evidence of risks associated with duration of hyperthyroidism, strategies to improve optimization of initial dosing are needed. Pending further subgroup analysis by presenting FT4 severity, these preliminary results suggest and approach factoring other variables apart from guideline based initial ATD dose is needed to optimize response. Our data will be utilized to pilot an individualized, patient specific predictive model to guide initial dosing to this end.

AbstractObjectiveTo describe the presentation and outcomes of patients with adrenal ganglioneuromas (AGNs).DesignSingle‐centre retrospective cohort study (1 January 1995 to 31 December 2019) and systematic review of literature (1 January 1980 to 19 November 2019).PatientsDiagnosed with histologically confirmed AGN.MeasurementsBaseline clinical, imaging and biochemical characteristics, recurrence rates and mortality. Subgroup analysis was performed on tumours with histologic elements of ganglioneuroma and pheochromocytoma (ie composite tumours).ResultsThe cohort study included 45 patients with AGN, 20 (44%) of which had composite tumours. Compared to pure AGN, patients with composite tumour were older (median age, 62.5 vs. 35 years, p < .001), had smaller tumours (median size, 3.9 vs. 5.7 cm, p = .016) and were discovered incidentally less frequently (65% vs. 84%, p = .009). No recurrences or ganglioneuroma‐specific mortality occurred during follow‐up (range, 0–266 months). The systematic review included 14 additional studies and 421 patients. The mean age of diagnosis was 39 years, and 47% were women. AGNs were discovered incidentally in 72% of patients, were predominantly unilateral (99%) and had a mean diameter of 5.8 cm and an unenhanced computed tomography (CT) attenuation of −118 to 49 Hounsfield units (HU). On imaging, 69% of AGNs were homogenous, 41% demonstrated calcifications, and 40% were lobulated.ConclusionsAGNs are rare benign tumours that present with variable imaging features including large size, unenhanced CT attenuation >20 HU, calcifications and lobulated shape. Imaging characteristics can assist in establishing a diagnosis and avoiding an unnecessary adrenalectomy. The association of pheochromocytomas with AGNs is frequent. Diagnosis should include biochemical testing.

Objective Our aim was to determine the radiologic and clinicopathologic characteristics of thyroid nodules with focal 68Ga-DOTATATE activity. Methods In this retrospective study of 1927 consecutive 68Ga-DOTATATE PET scans, 85 patients with incidental and nonincidental focal 68Ga-DOTATATE avid thyroid nodules were identified, of which 31 patients with 33 thyroid nodules underwent fine-needle aspiration (FNA) or surgery. These 33 nodules were reviewed for Krenning score and SUVmax of the thyroid nodule, contralateral thyroid lobe and left atrium. Results Cytology/histopathology included 58% (19/33) with benign findings, 18% (6/33) medullary thyroid carcinoma (MTC), 9% (3/33) atypia or follicular lesion of undetermined significance (AUS/FLUS), 9% (3/33) suspicious for follicular neoplasm and Hurthle cell adenoma (SFN/HCA) and 6% (2/33) nondiagnostic cytology. Median serum calcitonin was 1156 pg/mL (range, 460–1828) in MTC and was <5.0 pg/mL (<5.0–12.5) in patients with benign nodules. Nodules had Krenning score of 1, 2 and 3 in 46% (15/33), 27% (9/33) and 27% (9/33). The majority of MTC and AUS/FLUS nodules had a Krenning score of 3, and there was substantial intragroup variation in Krenning score among the benign nodules. The mean SUVmax for the entire cohort was 5.5 ± 2.9 (mean ± SD), and the range was 2.0–13.0. There was overlap in the nodule/contralateral thyroid SUVmax ratios between groups. The MTC and AUS/FLUS nodules tended to have a higher nodule/blood pool SUVmax ratio than the other pathologic groups. Conclusion There was considerable variation in radiologic characteristics among benign thyroid nodules. The ratio of thyroid nodule SUVmax/blood pool SUVmax may be useful to differentiate pathologic groups, but larger studies are needed to investigate this further. Given the potential for malignancy in thyroid nodules with focal 68Ga-DOTATATE activity, further evaluation with serum calcitonin and FNA may be considered. Video Abstract: http://links.lww.com/NMC/A186

Abstract Background: Pseudohypoparathyroidism (PHP) is a heterogeneous group of disorders characterized by end-organ resistance to PTH. Most subtypes are caused by pathogenic variants or epigenetic alterations in GNAS, which encodes the alpha subunit of the G protein regulating end-organ response to PTH. PHP type 1B (PHP1B) is caused by methylation defects in GNAS and presents with isolated renal PTH resistance. Clinical Case: A 29-year-old gentleman presented with intermittent muscle spasms, perioral and digital paresthesias, fatigue, and anxiety. Family history was notable for similar symptoms in his sister and nephew. Physical examination revealed normal stature, non-dysmorphic facies, and no soft tissue ossifications or skeletal anomalies. Chvostek sign was positive. Laboratory studies showed total calcium 6.0 mg/dL (n 8.6–10.0 mg/dL), phosphorus 6.8 mg/dL (n 2.5–3.5 mg/dL), creatinine 0.8 mg/dL (n 0.8–1.3 mg/dL), albumin 5.0 (n 3.5–5.0 mg/dL), PTH 231 pg/mL (n 15–65 pg/mL), total 25-hydroxyvitamin D 19 mg/mL (n 20–50 ng/mL), and 1,25-dihydroxyvitamin D 45 pg/mL (n 18–64 pg/mL). Additional endocrine testing showed TSH 6.4 mIU/L (n 0.3–4.2 mIU/L), free T4 1.1 ng/dL (n 0.9–1.7 ng/dL), and TPO antibody &lt;0.3 IU/mL (n &lt;9.0 IU/mL). Renal ultrasound was normal. CT head showed diffuse intracranial calcifications. He was diagnosed with PHP1B and started on calcitriol, cholecalciferol, and calcium carbonate. He declined genetic testing. Repeat laboratory studies were improved with total calcium 8.5 mg/dL, phosphorus 3.9 mg/dL, total 25-hydroxyvitamin D 49 mg/mL, PTH 124 pg/mL, and 24-hour urinary calcium 269 mg (n &lt;250 mg). Conclusion: International consensus guidelines for the diagnosis and management of PHP and related disorders were recently published by Mantovani et al. in 2018. Proposed clinical and biochemical major criteria include PTH resistance, ectopic ossifications, early-onset obesity, TSH resistance, and Albright hereditary osteodystrophy (AHO; round facies, short stature, brachydactyly, developmental delay). Unlike PHP type 1A, PHP1B often presents later in life and features of AHO are usually absent, so diagnosis requires a high degree of clinical suspicion. It is recommended that patients with suspected PHP have molecular confirmation with sequencing, methylation, and/or copy number variant analysis of GNAS. Routine monitoring of calcium, phosphorus, and PTH levels and treatment with active vitamin D analogues with or without calcium supplements are advised to maintain normal calcium and phosphorus and PTH &lt;2 times the upper limit of normal. Other recommendations include renal imaging for nephrocalcinosis, eye exam for cataracts, CT head imaging (in patients with neurological findings) for calcifications, regular dental care, and management of comorbid endocrinopathies. A multidisciplinary approach is needed in this complex, heterogeneous group of disorders.

Abstract Introduction: Anti-thyroid Drugs (ATD) have become the most frequently used treatment for Graves’ disease (GD) in the United States. However, the response to this therapy is variable. Factors that predict biochemically responsive vs. biochemically persistent disease remain unknown. Identifying predictors of disease poorly responsive to ATD can help guide treatment decision making, follow up planning and prognosis. Methods: From a database of patients with GD treated with ATD and receiving care at an academic medical center between 2009–2019, we selected adults with incident GD treated with ≥14 days of ATD. Results: 172 patients (from a database of 730 patients with GD on ATD) were sampled for the purpose of this pilot and 97 of these met inclusion criteria. Patients had a median age of 50 (18–90); female, 70.1%; never smokers, 64.9%; median goiter size of 40 g (15–100); and median TRAb on presentation of 8.1 mIU/L (1.0- 60). Graves’ orbitopathy (GO) was present in 13.4% at baseline. Patients (100%) were started on methimazole at a median dose of 20 mg (2.5–60). The median time from presentation until biochemical improvement (defined as the first instance of FT4 ≤1.7 ng/dL) was 120.9 days (18–1525), and to biochemical euthyroidism (normal TSH & FT4) was 251 days (41–1259) including a median of 3 (0–17) dose adjustments. In a univariate analysis, response to ATD was divided into two groups; biochemically responsive and biochemically persistent disease (based on reaching biochemical improvement in ≤6 months, or &gt;6 months respectively). Biochemically persistent disease was more common in those with GO at presentation (38.5% vs.11.1%) (p .024). There was a trend towards greater prevalence of biochemically persistent disease in those with TRAb ≥ 8.0 mIU/L (46.2% vs. 27.8%) (p .204), and goiter estimated 30 grams or above by physical examination (30.8% vs. 19.4%) (p .460). Biochemically responsive disease was associated with higher frequency of hypothyroidism during treatment (p .047). Conclusion: Our preliminary results illustrate the spectrum of response to ATD and predictors of biochemically persistent disease. We aim to expand this analysis utilizing a large database. As use of ATD increases, clinicians and patients can apply this data to estimate response to therapy, and identify patients that may require more aggressive therapy, thereby tailoring management plans.

Metastatic pheochromocytoma and paraganglioma (PPGL) are incurable neuroendocrine tumors. The goals of treatment include palliating symptoms and reducing tumor burden. Little is known about the use of radiofrequency ablation (RFA), cryoablation (CRYO), and percutaneous ethanol injection (PEI) to treat metastatic PPGL. We performed a retrospective study of patients age 17 years and older with metastatic PPGL who were treated with ablative therapy at Mayo Clinic, USA, between June 14, 1999 and November 14, 2017. Our outcomes measures were radiographic response, procedure-related complications, and symptomatic improvement. Thirty-one patients with metastatic PPGL had 123 lesions treated during 42 RFA, 23 CRYO, and 4 PEI procedures. The median duration of follow-up was 60 months (range, 0–163 months) for non-deceased patients. Radiographic local control was achieved in 69/80 (86%) lesions. Improvement in metastasis-related pain or symptoms of catecholamine excess was achieved in 12/13 (92%) procedures. Thirty-three (67%) procedures had no known complications. Clavien-Dindo Grade I, II, IV, and V complications occurred after 7 (14%), 7 (14%), 1 (2%), and 1 (2%) of the procedures, respectively. In patients with metastatic PPGL, ablative therapy can effectively achieve local control and palliate symptoms.

Abstract CD36 is an endothelial cell (EC) receptor that mediates angiostatic activity and oxidative stress, which are important in ischemic disease and tumor progression. CD36 interacts with TSR domain proteins including thrombospondin-1. This results in a signal that is likely to initiate an antiangiogenic “switch," subsequently converting a growth factor-mediated proangiogenic response to an antiangiogenic response. However, in pathologic settings including malignant tumors, robust angiogenesis occurs despite the abundance of TSR-containing proteins in the microenvironment. This suggests that there is a mechanism by which TSR-mediated antiangiogenesis could be blunted via the localized downregulation of EC CD36 transcription. We previously reported that lysophosphatidic acid (LPA), a bioactive signaling phospholipid mediator, down-regulates microvascular EC (MVEC) CD36 transcription by protein kinase PKD-1 signaling via G protein coupled receptor LPA1,3. However, further elucidating the CD36 transcriptional mechanisms is critical to understanding the antiangiogenic switch. To this end, we recently discovered that obesity-derived LPA inhibited CD36 expression in tumor-associated ECs (TAECs). Similarly, inducing the constitutively active PKD-1 or PKD-CA expression also resulted in CD36 downregulation. Mechanistically, LPA treatment led to nuclear accumulation of PKD-1, HDAC7 and FoxO1. Furthermore, LPA-mediated PKD-1 signaling enhanced FoxO1-HDAC7 interaction in the nucleus. This interaction was attenuated with PKD-1 silencing. Intriguingly, doxycycline induced PKD-CA expression increased ephrin B2 expression and ERK activation, which are two critical “molecular signatures” involved in arteriogenesis. Functionally, FGF-2 induced a potent proangiogenic response even in the presence of TSP-1 in ECs pre-treated with LPA. Doxycycline induced PKD-CA expression stimulated robust arterial EC branching in a 3D spheroid assay. This angiogenic response was inhibited by a novel PKD-1 specific inhibitor. Moreover, in a mouse Lewis lung carcinoma model, we detected a minimal level of endothelial CD36 expression with robust tumor angiogenesis. The role of PKD-1 signaling in CD36 transcriptional repression and tumor arteriogenesis is a critical yet underexplored and underappreciated field. We propose that the LPA-PKD-FoxO1 signaling axis is essential for CD36 transcriptional repression and arteriogenic signaling and responses. The PKD-1 stimulated nuclear signaling network is critical to epigenetic suppression of CD36 transcription and silencing of CD36 antiangiogenic switch, subsequently turning on the angiogenic switch and stimulating the arteriogenic responses. Targeting the LPA-PKD1-FoxO1 signaling axis could have therapeutic potential in the ischemic disease and malignant tumors. Citation Format: Jacob D. Kohlenberg, Yiliang Chen, Brad Best, Peter Storz, Randall T. Peterson, Roy Silverstein, Bin Ren. A novel LPA-PKD1-FoxO1 pathway in endothelial cells provides an angiogenic switch via down-regulation of CD36 transcription and induction of arteriogenic responses . [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-338. doi:10.1158/1538-7445.AM2013-LB-338