Citations

BACKGROUND Pheochromocytomas are rare catecholamine-producing tumors derived in more than 30% of cases from mutations in 9 tumor-susceptibility genes identified to date, including von Hippel-Lindau tumor suppressor (VHL); succinate dehydrogenase complex, subunit B, iron sulfur (Ip) (SDHB); and succinate dehydrogenase complex, subunit D, integral membrane protein (SDHD). Testing of multiple genes is often undertaken at considerable expense before a mutation is detected. This study assessed whether measurements of plasma metanephrine, normetanephrine, and methoxytyramine, the O-methylated metabolites of catecholamines, might help to distinguish different hereditary forms of the tumor. METHODS Plasma concentrations of O-methylated metabolites were measured by liquid chromatography with electrochemical detection in 173 patients with pheochromocytoma, including 38 with multiple endocrine neoplasia type 2 (MEN 2), 10 with neurofibromatosis type 1 (NF1), 66 with von Hippel-Lindau (VHL) syndrome, and 59 with mutations of SDHB or SDHD. RESULTS In contrast to patients with VHL, SDHB, and SDHD mutations, all patients with MEN 2 and NF1 presented with tumors characterized by increased plasma concentrations of metanephrine (indicating epinephrine production). VHL patients usually showed solitary increases in normetanephrine (indicating norepinephrine production), whereas additional or solitary increases in methoxytyramine (indicating dopamine production) characterized 70% of patients with SDHB and SDHD mutations. Patients with NF1 and MEN 2 could be discriminated from those with VHL, SDHB, and SDHD gene mutations in 99% of cases by the combination of normetanephrine and metanephrine. Measurements of plasma methoxytyramine discriminated patients with SDHB and SDHD mutations from those with VHL mutations in an additional 78% of cases. CONCLUSIONS The distinct patterns of plasma catecholamine O-methylated metabolites in patients with hereditary pheochromocytoma provide an easily used tool to guide cost-effective genotyping of underlying disease-causing mutations.

BACKGROUND The limits of chromatographic speed and mechanical frontend capabilities have been reached for many high-volume liquid chromatography–tandem mass spectrometry (LC-MS/MS) tests, curtailing the maximal achievable sample throughput. To overcome these boundaries, we developed and validated a derivatization-based sample-multiplex LC-MS/MS assay for detection of 25-hydroxyvitamins D2 and D3 [25(OH)D2 and 25(OH)D3], which increased sample throughput 5-fold. METHODS After separate derivatization with 1 of 5 different triazoline-diones (TADs), 5 calibrators, controls, or patient specimens were combined and injected together into an LC-MS/MS. On the basis of mass differences between TADs, the MS/MS quantified analyte and stable isotope internal standards for 25(OH)D2 and 25(OH)D3 for each respective multiplexed sample within the injection. Limits of detection and quantification, spiked recovery, linearity, imprecision, and patient results were determined and compared against our standard LC-MS/MS assay. RESULTS TAD multiplexing increased throughput on an LC-quadruplexed LC-MS/MS system from 60 samples/h to 300 samples/h. Limits of detection and quantification were 4.9 nmol/L [2 μg/L, 25(OH)D2], 2.2 nmol/L [0.9 μg/L, 25(OH)D3], and 10 nmol/L [4 μg/L, 25(OH)D2], 5 nmol/L [2 μg/L, 25(OH)D3], respectively. The assay was linear to 250 nmol/L (100 μg/L). Interassay CVs across the reportable range were 3.7%–15.2%. Spiked recoveries were 94%–119%. The method comparison with the standard LC-MS/MS method showed slopes of 0.96 and 0.97 (Deming regression) for 25(OH)D2 (n = 1733) and 25(OH)D3 (n = 7614) (R2=0.96 and 0.97), respectively. CONCLUSIONS Multiplexing samples by differential mass tagging in LC-MS/MS measurement of 25(OH)D2 and 25(OH)D3 allows for reliable quantification, with throughput increased over standard methods by the multiplexing factor.

The colonic mucus layer serves as an important barrier and prevents colonic bacteria from invading the mucosa and cause inflammation. The regulation of colonic mucus secretion is poorly understood. The aim of this study was to investigate the role of the mucus barrier in induction of colitis. Furthermore, regulation of mucus secretion by luminal bacterial products was studied. The colon of anesthetized Muc2 −/− , Muc1 −/− , wild-type (wt), and germ-free mice was exteriorized, the mucosal surface was visualized, and mucus thickness was measured with micropipettes. Colitis was induced by DSS (dextran sodium sulfate, 3%, in drinking water), and disease activity index (DAI) was assessed daily. The colonic mucosa of germ-free and conventionally housed mice was exposed to the bacterial products LPS (lipopolysaccharide) and PGN (peptidoglycan). After DSS induction of colitis, the thickness of the firmly adherent mucus layer was significantly thinner after 5 days and onward, which paralleled the increment of DAI. Muc2 −/− mice, which lacked firmly adherent mucus, were predisposed to colitis, whereas Muc1 −/− mice were protected with significantly lower DAI by DSS compared with wt mice. The mucus barrier increased in Muc1 −/− mice in response to DSS, whereas significantly fewer T cells were recruited to the inflamed colon. Mice housed under germ-free conditions had an extremely thin adherent colonic mucus layer, but when exposed to bacterial products (PGN or LPS) the thickness of the adherent mucus layer was quickly restored to levels observed in conventionally housed mice. This study demonstrates a correlation between decreasing mucus barrier and increasing clinical symptoms during onset of colitis. Mice lacking colonic mucus (Muc2 −/− ) were hypersensitive to DSS-induced colitis, whereas Muc1 −/− were protected, probably through the ability to increase the mucus barrier but also by decreased T cell recruitment to the afflicted site. Furthermore, the ability of bacteria to regulate the thickness of the colonic mucus was demonstrated.

Purpose The appropriate treatment for MSCC is controversial. A small randomized trial showed that decompressive surgery followed by radiotherapy was superior to radiotherapy alone. That study was limited to highly selected patients. Additional studies comparing surgery plus radiotherapy to radiotherapy could better clarify the role of surgery. Methods Data from 108 patients receiving surgery plus radiotherapy were matched to 216 patients (1:2) receiving radiotherapy alone. Groups were matched for 11 potential prognostic factors and compared for post-treatment motor function, ambulatory status, regaining ambulatory status, local control, and survival. Subgroup analyses were performed for patients receiving adequate surgery (direct decompressive surgery plus stabilization of involved vertebrae), patients receiving laminectomy, patients with solid tumors, patients with solid tumors receiving adequate surgery, and patients with solid tumors receiving laminectomy. Results Improvement of motor function occurred in 27% of patients after surgery plus radiotherapy and 26% after radiotherapy alone (P = .92). Post-treatment ambulatory rates were 69% after surgery plus radiotherapy and 68% after radiotherapy alone (P = .99). Of the nonambulatory patients, 30% and 26%, respectively, (P = .86) regained ambulatory status after treatment. One-year local control rates were 90% after surgery plus radiotherapy and 91% after radiotherapy alone (P = .48). One-year overall survival rates were 47% and 40%, respectively (P = .50). The subgroup analyses did not show significant differences between both groups. Surgery-related complications occurred in 11% of patients. Conclusion In this study, the outcomes of the end points evaluated after radiotherapy alone appeared similar to those of surgery plus radiotherapy. A new randomized trial comparing both treatments is justified.

Abstract Context: Prenatal androgen excess can cause a phenocopy of polycystic ovary syndrome (PCOS) in mammals. Retrospective studies have suggested that girls at risk for PCOS have low birth weight, and prospective studies have suggested an increased prevalence of small-for-gestational-age offspring in women with PCOS. Objective: The objective of the study was to determine whether infants of women with PCOS have reduced birth weight or increased intrauterine androgen levels. Design: This was a prospective case-control study. Participants: Thirty-nine PCOS and 31 control women and their infants participated in the study. Main Outcome Measures: Birth weight and mixed cord blood testosterone, androstenedione (A), dehydroepiandrosterone, 17-hydroxyprogesterone, estradiol (E2), and dihydrotestosterone levels were measured. Results: Mean birth weight did not differ, but there was a significant increase in the prevalence of large-for-gestational-age infants in the PCOS group. Cord blood E2 and A levels were lower (P < 0.05), but testosterone to E2 ratios did not differ in female PCOS compared with control offspring. There was no difference in E2 and A levels in the male PCOS and control offspring. There was no difference in 17-hydroxyprogesterone or other androgen levels in either male or female PCOS offspring compared with their respective control group. Conclusion: Infants of women with PCOS were more likely to be large for gestational age. Female offspring of affected women have lower cord blood A levels; other cord blood androgen levels do not differ compared with female control offspring. Cord blood E2 levels are also significantly decreased in PCOS, without any difference in the testosterone to E2 ratio, suggesting decreased fetal or placental production of steroids.

Abstract Background: Molecular testing of thyroid malignancies, in combination with cytologic and histologic examination, is becoming increasingly attractive as a tool for refining traditional morphologic diagnosis. The molecular changes associated with follicular thyroid carcinoma (FTC) are point mutations in RAS oncogenes or the presence of PAX8/PPARG (paired box 8/peroxisome proliferator-activated receptor gamma) rearrangement. Methods: We developed and validated a clinical assay for the detection of PAX8/PPARG rearrangements that uses a 4-color reverse-transcription PCR (RT-PCR) assay and high-resolution fragment analysis. Results: The RT-PCR assay is applicable for detecting the various described fusion transcripts of PAX8/PPARG in formalin-fixed, paraffin-embedded thyroid tissue and in fine-needle aspirate biopsy washes from thyroid nodules. The analytical sensitivity of the assay is 1 abnormal cell in a background of 100–10 000 translocation-negative cells. A comparison of the RT-PCR assay with dual-fusion fluorescence in situ hybridization showed an overall concordance of 95%. With this assay, we obtained a prevalence for the PAX8/PPARG rearrangement in FTC of 62% (13 of 21 cases), compared with a 5% prevalence (3 of 55) for other follicular cell–derived neoplasms. Conclusions: The introduction of this assay into clinical practice could provide useful information for the diagnosis and possibly for the prognosis and treatment of thyroid cancer in the future.

Abstract Background: Immunoassays specific for 1–84 parathyroid hormone (PTH) reportedly reflect the bioactivity of PTH; however, PTH immunoassays can be susceptible to interference by cross-reacting PTH fragments. In addition, these assays currently lack standardization. A methodology using immunocapture purification with liquid chromatography–tandem mass spectrometry (LC-MS/MS) detection, along with a stable isotope–labeled internal standard, may help address these issues. Methods: We isolated 1–84 PTH from 1 mL serum by immunocapture on a 6.5-mm polystyrene bead. The immobilized PTH was digested in situ and analyzed by LC-MS/MS. For quantification, we used the selected reaction monitoring response from the N-terminal tryptic peptide 1–13 PTH (1SVSEIQLMHNLGK13). Results: The linear range of the assay was 39.1–4560 ng/L, and the limit of detection and limit of quantification were 14.5 ng/L and 39.1 ng/L, respectively. The intraassay CVs ranged from 6% to 11%, and the interassay CVs ranged from 7% to 17%. Interference by PTH fragments 1–44 PTH, 7–84 PTH, 43–68 PTH, 52–84 PTH, 64–84 PTH, and PTH-related protein (PTHrP) was ≤1% to ≤0.001%. Method comparison of LC-MS/MS vs the Roche Cobas® immunoassay yielded Deming fit of LC-MS/MS = 1.01x immunoassay – 13.21. The mean bias by Bland–Altman plot was −9.4%. Conclusions: In patients with hyperparathyroidism, the immunocapture in situ digestion LC-MS/MS method can provide accurate and precise PTH results compared with immunoassay.