Impact of a change to a novel chemiluminescent immunoassay for measuring plasma aldosterone on the diagnosis of primary aldosteronism.

In Japan, the standard method for measuring plasma aldosterone concentration (PAC) for primary aldosteronism (PA) diagnosis was changed from radioimmunoassay (RIA) to a novel chemiluminescent enzyme immunoassay (CLEIA). The purpose of this study is to simulate the possible impact of the change on PA diagnosis. This retrospective study assessed 2,289 PA patients. PACs measured by conventional RIA were transformed to estimated PACs (CLEIA) as follows: RIA (pg/mL) = 1.174 × CLEIA (pg/mL) + 42.3. We applied the estimated PAC (CLEIA) to the conventional cut-off of aldosterone-to-renin activity ratio ≥200 for screening and captopril challenge test (CCT) and PAC ≥60 pg/mL for saline infusion test (SIT). Application of the estimated PAC to screening and confirmatory tests decreased the number of PA diagnoses by 36% (743/2,065) on CCT and 52% (578/1,104) on SIT (discrepant cases). Among the discrepant cases, 87% (548/628) of CCT and 87% (452/522) of SIT were bilateral on adrenal venous sampling (AVS). Surgically treatable aldosterone-producing adenomas (APAs) were observed in 6% (36/579) and 5% (23/472) of discrepant cases on CCT and SIT, respectively; most were characterized by hypokalemia and/or adrenal nodule on CT imaging. Application of the PAC measured by the novel CLEIA to conventional cut-offs decreases the number of PA diagnoses. Although most discrepant cases were bilateral on AVS, there are some APA cases that were characterized by hypokalemia and/or adrenal tumor on CT. Further studies which evaluate PACs measured by both RIA and CLEIA for each patient are needed to identify new cut-offs for PAC measured by CLEIA.

Japan Endocrine Society clinical practice guideline for the diagnosis and management of primary aldosteronism 2021.

Primary aldosteronism (PA) is associated with higher cardiovascular morbidity and mortality rates than essential hypertension. The Japan Endocrine Society (JES) has developed an updated guideline for PA, based on the evidence, especially from Japan. We should preferentially screen hypertensive patients with a high prevalence of PA with aldosterone to renin ratio ≥200 and plasma aldosterone concentrations (PAC) ≥60 pg/mL as a cut-off of positive results. While we should confirm excess aldosterone secretion by one positive confirmatory test, we could bypass patients with typical PA findings. Since PAC became lower due to a change in assay methods from radioimmunoassay to chemiluminescent enzyme immunoassay, borderline ranges were set for screening and confirmatory tests and provisionally designated as positive. We recommend individualized medicine for those in the borderline range for the next step. We recommend evaluating cortisol co-secretion in patients with adrenal macroadenomas. Although we recommend adrenal venous sampling for lateralization before adrenalectomy, we should carefully select patients rather than all patients, and we suggest bypassing in young patients with typical PA findings. A selectivity index ≥5 and a lateralization index >4 after adrenocorticotropic hormone stimulation defines successful catheterization and unilateral subtype diagnosis. We recommend adrenalectomy for unilateral PA and mineralocorticoid receptor antagonists for bilateral PA. Systematic as well as individualized clinical practice is always warranted. This JES guideline 2021 provides updated rational evidence and recommendations for the clinical practice of PA, leading to improved quality of the clinical practice of hypertension.

The complexity of intercellular localisation of alkaloids revealed by single-cell metabolomics.

Catharanthus roseus is a medicinal plant well known for producing bioactive compounds such as vinblastine and vincristine, which are classified as terpenoid indole alkaloids (TIAs). Although the leaves of this plant are the main source of these antitumour drugs, much remains unknown on how TIAs are biosynthesised from a central precursor, strictosidine, to various TIAs in planta. Here, we have succeeded in showing, for the first time in leaf tissue of C. roseus, cell-specific TIAs localisation and accumulation with 10 µm spatial resolution Imaging mass spectrometry (Imaging MS) and live single-cell mass spectrometry (single-cell MS). These metabolomic studies revealed that most TIA precursors (iridoids) are localised in the epidermal cells, but major TIAs including serpentine and vindoline are localised instead in idioblast cells. Interestingly, the central TIA intermediate strictosidine also accumulates in both epidermal and idioblast cells of C. roseus. Moreover, we also found that vindoline accumulation increases in laticifer cells as the leaf expands. These discoveries highlight the complexity of intercellular localisation in plant specialised metabolism.

Cell-specific localization of alkaloids in Catharanthus roseus stem tissue measured with Imaging MS and Single-cell MS.

Catharanthus roseus (L.) G. Don is a medicinal plant well known for producing antitumor drugs such as vinblastine and vincristine, which are classified as terpenoid indole alkaloids (TIAs). The TIA metabolic pathway in C. roseus has been extensively studied. However, the localization of TIA intermediates at the cellular level has not been demonstrated directly. In the present study, the metabolic pathway of TIA in C. roseus was studied with two forefront metabolomic techniques, that is, Imaging mass spectrometry (MS) and live Single-cell MS, to elucidate cell-specific TIA localization in the stem tissue. Imaging MS indicated that most TIAs localize in the idioblast and laticifer cells, which emit blue fluorescence under UV excitation. Single-cell MS was applied to four different kinds of cells [idioblast (specialized parenchyma cell), laticifer, parenchyma, and epidermal cells] in the stem longitudinal section. Principal component analysis of Imaging MS and Single-cell MS spectra of these cells showed that similar alkaloids accumulate in both idioblast cell and laticifer cell. From MS/MS analysis of Single-cell MS spectra, catharanthine, ajmalicine, and strictosidine were found in both cell types in C. roseus stem tissue, where serpentine was also accumulated. Based on these data, we discuss the significance of TIA synthesis and accumulation in the idioblast and laticifer cells of C. roseus stem tissue.

Accuracy of adrenal computed tomography in predicting the unilateral subtype in young patients with hypokalaemia and elevation of aldosterone in primary aldosteronism.

CONTEXT: The current Endocrine Society Guideline suggests that patients aged <35 years with marked primary aldosteronism (PA) and unilateral adrenal lesions on adrenal computed tomography (CT) scan may not need adrenal vein sampling (AVS) before proceeding to unilateral adrenalectomy. This suggestion is, however, based on the data from only one report in the literature. OBJECTIVE: We sought to determine the accuracy of CT findings in young PA patients who had unilateral adrenal disease on CT with hypokalaemia and elevation of aldosterone. DESIGN AND PATIENTS: We retrospectively studied 358 PA patients (n = 30, aged <35 years; n = 39, aged 35-40 years; n = 289, aged ≥40 years) with hypokalaemia and elevation of aldosterone and unilateral disease on CT who had successful AVS. MAIN OUTCOME MEASURE: Accuracy of CT findings is determined by AVS findings and/or surgical outcomes in patients aged <35 years. RESULTS: Concordance of the diagnosis between CT and AVS was 90% (27/30) in patients aged <35 years, 79% (31/39) in patients aged 35-40 years and 69% (198/289) in those aged ≥40 years (trend for P < .01). Surgical benefit was confirmed in three patients aged <35 years and in three patients aged 35-40 years with the available surgical data who had discordance between CT and AVS findings. Collectively, the diagnostic accuracy of CT findings was 100% (30/30) if aged <35 years and 87% (34/39) if aged 35-40 years. CONCLUSION: Primary aldosteronism patients aged <35 years with hypokalaemia and elevation of aldosterone and unilateral disease on adrenal CT could be spared AVS.

Spatially resolved metabolic distribution for unraveling the physiological change and responses in tomato fruit using matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI).

Information on spatiotemporal metabolic behavior is indispensable for a precise understanding of physiological changes and responses, including those of ripening processes and wounding stress, in fruit, but such information is still limited. Here, we visualized the spatial distribution of metabolites within tissue sections of tomato (Solanum lycopersicum L.) fruit using a matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) technique combined with a matrix sublimation/recrystallization method. This technique elucidated the unique distribution patterns of more than 30 metabolite-derived ions, including primary and secondary metabolites, simultaneously. To investigate spatiotemporal metabolic alterations during physiological changes at the whole-tissue level, MALDI-MSI was performed using the different ripening phenotypes of mature green and mature red tomato fruits. Although apparent alterations in the localization and intensity of many detected metabolites were not observed between the two tomatoes, the amounts of glutamate and adenosine monophosphate, umami compounds, increased in both mesocarp and locule regions during the ripening process. In contrast, malate, a sour compound, decreased in both regions. MALDI-MSI was also applied to evaluate more local metabolic responses to wounding stress. Accumulations of a glycoalkaloid, tomatine, and a low level of its glycosylated metabolite, esculeoside A, were found in the wound region where cell death had been induced. Their inverse levels were observed in non-wounded regions. Furthermore, the amounts of both compounds differed in the developmental stages. Thus, our MALDI-MSI technique increased the understanding of the physiological changes and responses of tomato fruit through the determination of spatiotemporally resolved metabolic alterations. Graphical abstract ᅟ.

Development and Application of a High-Resolution Imaging Mass Spectrometer for the Study of Plant Tissues.

Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) or imaging mass spectrometry (imaging MS) has been a powerful tool to map the spatial distribution of molecules on the surface of biological materials. This technique has frequently been applied to animal tissue slices for the purpose of mapping proteins, peptides, lipids, sugars or small metabolites to find disease-specific biomarkers or to study drug metabolism. Recently, it has also been applied to intact plant tissues or thin slices thereof using commercial mass spectrometers. The present work is concerned with the refinement of MALDI/laser desorption/ionization (LDI)-Fourier transform ion cyclotron resonance (FTICR)-MS incorporating certain specific features namely, ultra-high mass resolution (>100,000), ultra-high molecular mass accuracy (<1 p.p.m.) and high spatial resolution (<10 µm) for imaging MS of plant tissues. Employing an in-house built mass spectrometer, the imaging MS analysis of intact Arabidopsis thaliana tissues, namely etiolated seedlings and roots of seedlings, glued to a small transparent ITO (indium tin oxide)-coated conductive glass was performed. A matrix substance was applied to the vacuum-dried intact tissues by sublimation prior to the imaging MS analysis. The images of various small metabolites representing their two-dimensional distribution on the dried intact tissues were obtained with or without different matrix substances. The effects of MALDI matrices on the ionization of small metabolites during imaging MS acquisition are discussed.

[ADRENAL HEMORRHAGE: 6 CASES AND A REVIEW OF 57 REPORTED CASES].

PURPOSE: The guidelines on adrenal hemorrhage has not established in Japan. In this article, we discuss the management of adrenal hemorrhage. OBJECTS AND METHODS: We experienced 6 patients from November 2004 to September 2013 in The University of Tokyo Hospital and The Fraternity Memorial Hospital, and we searched 57 cases already reported in Japan by using Japan Medical Abstracts Society (http://search.jamas.or.jp/). So we analyzed total 63 adrenal hemorrhage cases in Japan. RESULTS: In 63 cases, 5 cases were performed TAE, 3 cases were performed emergent surgeries, 13 cases were managed conservatively and elective surgeries were performed in the other cases. 5 cases were fulfilled criteria for Hb < 10 g/dl and the maximum diameter of the hematoma > 10 cm. Of 5 cases, 4 cases were performed emergent hemostasis. CONCLUSIONS: Adrenal hemorrhages caused by metastatic tumor tend to be serious anemia. In addition, the most patients with adrenal hemorrhages, who had Hb < 10 g/dl and the maximum diameter of the hematoma > 10 cm, required immediate medical treatment, e.g. TAE or surgical hemostasis.

Comparison of the antialbuminuric effects of benidipine and hydrochlorothiazide in Renin-Angiotensin System (RAS) inhibitor-treated hypertensive patients with albuminuria: the COSMO-CKD (COmbination Strategy on Renal Function of Benidipine or Diuretics TreatMent with RAS inhibitOrs in a Chronic Kidney Disease Hypertensive Population) study.

OBJECTIVE: This study evaluated the non-inferiority of renoprotection afforded by benidipine versus hydrochlorothiazide in hypertensive patients with chronic kidney disease (CKD). METHODS: In this prospective, multicenter, open-labeled, randomized trial, the antialbuminuric effects of benidipine and hydrochlorothiazide were examined in renin-angiotensin system (RAS) inhibitor-treated patients with blood pressure (BP) readings of ≥ 130/80 mmHg and ≤ 180/110 mmHg, a urinary albumin to creatinine ratio (UACR) of ≥ 300 mg/g, and an estimated glomerular filtration rate (eGFR) of ≥ 30 ml/min/1.73m(2). Patients received benidipine (n = 176, final dose: 4.8 mg/day) or hydrochlorothiazide (n = 170, 8.2 mg/day) for 12 months. RESULTS: Benidipine and hydrochlorothiazide exerted similar BP- and eGFR-decreasing actions. The UACR values for benidipine and hydrochlorothiazide were 930.8 (95% confidence interval: 826.1, 1048.7) and 883.1 (781.7, 997.7) mg/g at baseline, respectively. These values were reduced to 790.0 (668.1, 934.2) and 448.5 (372.9, 539.4) mg/g at last observation carried forward (LOCF) visits. The non-inferiority of benidipine versus hydrochlorothiazide was not demonstrated (benidipine/hydrochlorothiazide ratio of LOCF value adjusted for baseline: 1.67 (1.40, 1.99)). CONCLUSIONS: The present study failed to demonstrate the non-inferiority of the antialbuminuric effect of benidipine relative to that of hydrochlorothiazide in RAS inhibitor-treated hypertensive patients with macroalbuminuria.

Prevalence of unilateral hyperaldosteronism in primary aldosteronism: impact of a novel chemiluminescent immunoassay for measuring plasma aldosterone in Japan.

This study aims to evaluate the prevalence of unilateral hyperaldosteronism (UHA) and its clinical characteristics in patients with primary aldosteronism (PA), diagnosed using plasma aldosterone concentration (PAC) measured by chemiluminescent enzyme immunoassay (CLEIA). We retrospectively analyzed data of 199 PA patients from the Japan Primary Aldosteronism Study II (JPAS II) dataset, including patients who underwent adrenal venous sampling (AVS) and the captopril challenge test (CCT) and/or saline infusion test (SIT), with PAC measured by CLEIA. We focused on two categories: confirmed PA, where patients exhibit clear biochemical evidence of the disorder, and borderline PA, where patients present with marginal biochemical indicators, as outlined in the Japan Endocrine Society's clinical practice guideline for the diagnosis and management of PA. In confirmed PA cases, over the half of patients was UHA, while approximately 15 to 20% of borderline cases were found to be UHA. The prevalence of hypokalemia was identified as predictor of UHA among borderline cases. Among borderline cases with no hypokalemia and adrenal nodules on CT imaging, only 6 to 8% of patients were found to have UHA. Notably, some patients exhibited UHA despite negative results on one test but confirmed result on the other, particularly those with hypokalemia or adrenal nodules on CT imaging. In conclusion, the findings validate the importance of AVS in confirmed PA cases and the need for careful assessment in borderline cases. When feasible, conducting both CCT and SIT, and interpreting their results alongside other clinical indicators, could provide a more comprehensive assessment.

Infrared multiple photon dissociation spectroscopy and computational studies of O-glycosylated peptides.

The infrared multiple photon dissociation (IRMPD) spectra of O-glycosylated peptides in the gas phase were studied in the IR scanning range of 5.7-9.5 µm. Fragmentation of protonated and sodiated O-glycopeptides was investigated using electrospray ionization (ESI) Fourier-transform ion cyclotron resonance (FTICR) mass spectrometry (MS) with a free electron laser (FEL). FEL is used in the IRMPD technique as a tunable IR light source. In the IRMPD spectroscopic analysis of the protonated O-glycopeptide, fragment ions of the b/y and B/Y types were observed in the range of 5.7-9.5 µm, corresponding to the cleavage of the backbone in the parent amino acid sequence and glycosyl bonds, whereas the spectra of the sodiated glycopeptide showed major peaks of photoproducts of the B/Y type in the range of 8.4-9.5 µm. The IRMPD spectra of the O-glycopeptides were compared with simulated IR spectra for the structures obtained from the molecular dynamics.

Synergistic effects of high hydrostatic pressure, mild heating, and amino acids on germination and inactivation of Clostridium sporogenes spores.

The synergistic effects of high hydrostatic pressure (HHP), mild heating, and amino acids on the germination of Clostridium sporogenes spores were examined by determining the number of surviving spores that returned to vegetative growth after pasteurization following these treatments. Pressurization at 200 MPa at a temperature higher than 40°C and treatment with some of the 19 l-amino acids at 10 mM or higher synergistically facilitated germination. When one of these factors was omitted, the level of germination was insignificant. Pressures of 100 and 400 MPa were less effective than 200 MPa. The spores were effectively inactivated by between 1.8 and 4.8 logs by pasteurization at 80°C after pressurization at 200 MPa at 45°C for 120 min with one of the amino acids with moderate hydrophobicity, such as Leu, Phe, Cys Met, Ala, Gly, or Ser. However, other amino acids showed poor inactivation effects of less than 0.9 logs. Spores in solutions containing 80 mM of either Leu, Phe, Cys, Met, Ala, Gly, or Ser were successfully inactivated by pasteurization by more than 5.4 logs after pressurization at 200 MPa at 70°C for 15 to 120 min. Ala and Met reduced the spore viability by 2.8 and 1.8 logs, respectively, by pasteurization at a concentration of 1 mM under 200 MPa at 70°C. These results indicate that germination of the spores is facilitated by a combination of high hydrostatic pressure, mild heating, and amino acids.

Imaging MS Analysis in Catharanthus roseus.

To understand how the plant regulates metabolism, it is important to determine where metabolites localize in the tissues and cells. Single-cell level omics approaches in plants have shown remarkable development over the last several years, and this data has been instrumental in gene discovery efforts for enzymes and transporters involved in metabolism. For metabolomics, Imaging Mass Spectrometry (IMS) is a powerful tool to map the spatial distribution of molecules in the tissue. Here, we describe the methods which we used to reveal where secondary metabolites, primarily alkaloids, localize in Catharanthus roseus stem and leaf tissues.

Primary aldosteronism with mild autonomous cortisol secretion increases renal complication risk.

Objective: In primary aldosteronism (PA), renal impairment has been identified as an important comorbidity. Excess cortisol production also may lead to renal damage; thus, concomitant mild autonomous cortisol secretion (MACS) may predispose PA patients to renal disorders. However, there is limited evidence to support this claim. Therefore, this study aimed to determine whether the concurrence of MACS and PA increases the risk of renal complications. Design: This study is a retrospective cross-sectional study. Methods: A total of 1310 patients with PA were stratified into two groups according to 1 mg dexamethasone suppression test (DST) results (cut-off post-DST serum cortisol 1.8 µg/dL): MACS (n = 340) and non-MACS (n = 970). The prevalence of renal complications was compared between the group. We also performed multiple logistic regression analysis to determine factors that increase the risk for renal complications. Results: The prevalence of lowered estimated glomerular filtration rate (eGFR) and proteinuria was nearly twice higher in the MACS group than in the non-MACS group. Not only plasma aldosterone concentration (PAC) but also the presence of MACS was selected as independent factors that were associated with the two renal outcomes. The risk of lower eGFR or proteinuria in patients who had MACS and higher levels PAC was several folds higher than in those who had an absence of MACS and lower levels of PAC. Conclusions: MACS is an independent risk factor for renal complications in patients with PA, and MACS concomitant with higher aldosterone secretion in PA patients causes an increase in the risk of developing renal complications.

Case Report: Spontaneous Postpartum Quadruple Cervicocephalic Arterial Dissection With a Heterozygous COL5A1 Variant of Unknown Significance.

Pregnancy-associated cervicocephalic arterial dissection is rare, and its pathophysiology remains poorly understood. Despite the hypothesized contribution to pathogenesis, connective tissue diseases and genetic factors are rarely identified in clinical cases. We describe a case of postpartum arterial dissection involving all four cervicocephalic arteries resulting in acute cerebral infarction. The patient underwent successful endovascular thrombectomy and angioplasty and recovered fully without sequelae. Genetic screening for connective tissue diseases identified a heterozygous missense COL5A1 variant with unknown clinical significance. Two genetically related family members later developed arterial abnormalities, and one of them tested positive for the same COL5A1 gene variant as our patient, while the other was scheduled for genetic testing. The extensive clinical presentation of our patient and the prevalence of arterial abnormalities in her family warrant further assessment of the association between the identified COL5A1 gene variant and the pathogenesis of arterial dissections.

Guidelines for the diagnosis and treatment of primary aldosteronism--the Japan Endocrine Society 2009.

The Japan Endocrine Society (JES) attempted to develop guidelines for the diagnosis and treatment of primary aldosteronism (PA). The Task Force Committee (TFC) was composed of a chair, selected by the JES, and additional experts. Systematic reviews of available evidence for Japanese patients were used to recommend the key treatment and prevention. We have evaluated the methods of screening, confirmatory tests and imaging, plus adrenal vein sampling (AVS). Consensus was guided by systematic review of evidence and discussion during each annual meeting of the JES, plus its related meetings, and by e-mail communication. The drafts prepared by TFC were reviewed successively by the members of Research on Intractable Diseases provided by the Japanese Ministry of Health, Labour and Welfare, and in comments from the JES's councilors. At each stage of review, TFC received written comments and incorporated suggested changes. In conclusion, all patients with hypertension should be screened for PA, because of the high prevalence of cardiovascular disease and the current low case-detection rate in Japan. Case detection can be performed in hypertensive patients and those with hypokalemia by determining the aldosterone/renin ratio, and the diagnosis of PA can be confirmed by two of three confirmatory tests. The presence of a unilateral aldosterone-producing adenoma should be established/excluded by AVS by an experienced radiologist, optimally followed by laparoscopic adrenalectomy. In contrast, patients with bilateral adrenal hyperplasia, or those unsuitable for surgery, are optimally treated medically with mineralocorticoid receptor antagonists.

Efficacy and safety of esaxerenone (CS-3150), a newly available nonsteroidal mineralocorticoid receptor blocker, in hypertensive patients with primary aldosteronism.

Mineralocorticoid receptor (MR) blockers are very beneficial for patients with hypertension and primary aldosteronism (PA). We investigated the efficacy and safety of a newly available nonsteroidal MR blocker, esaxerenone, in Japanese patients with hypertension and PA. A multicenter, open-label study was conducted in Japan between October 2016 and July 2017. Patients with hypertension and PA received 12 weeks of treatment with esaxerenone, initiated at 2.5 mg/day and escalated to 5 mg/day during week 2 or 4 of treatment, based on individual response. The only other permitted antihypertensive therapies were stable dosages of a Ca2+ channel blocker or α-blocker. The primary efficacy outcome was a change in sitting systolic and diastolic blood pressure (SBP/DBP) from baseline to the end of treatment. Forty-four patients were included; dose escalation to 5 mg/day was implemented for 41 of these patients. Significant decreases in SBP and DBP were observed (point estimates [95% confidence interval] -17.7 [-20.6, -14.7] and -9.5 [-11.7, -7.3] mmHg, respectively; both p < 0.0001 at the end of treatment). Significant BP reductions were evident from week 2 and continued through to week 8; BP remained stable until week 12. The antihypertensive effect of esaxerenone on SBP was significantly greater in females and in patients receiving monotherapy. The major drug-related adverse events were serum K+ increase and estimated glomerular filtration rate decrease (both 4.5%, n = 2); no gynecomastia or breast pain was observed. We conclude that esaxerenone is a potent MR blocker with favorable efficacy and safety profiles in patients with hypertension and PA.

Prevalence of Germline Variants in a Large Cohort of Japanese Patients with Pheochromocytoma and/or Paraganglioma.

The high incidence of germline variants in pheochromocytoma and paraganglioma (PPGL) has been reported mainly in Europe, but not among Japanese populations in Asia. We aimed to study the prevalence of germline variants in Japanese PPGL patients and the genotype-phenotype correlation. We examined 370 PPGL probands, including 43 patients with family history and/or syndromic presentation and 327 patients with apparently sporadic (AS) presentation. Clinical data and blood samples were collected, and the seven major susceptibility genes (MAX, SDHB, SDHC, SDHD, TMEM127, VHL, and RET) were tested using Sanger sequencing. Overall, 120/370 (32.4%) patients had pathogenic or likely pathogenic variants, with 81/327 (24.8%) in AS presentation. SDHB was the most frequently mutated gene (57, 15.4%), followed by SDHD (27, 7.3%), and VHL (18, 4.9%). The incidence of metastatic PPGL was high in SDHB carriers (21/57, 36.8%). A few unique recurrent variants (SDHB c.137G>A and SDHB c.470delT) were detected in this Japanese cohort, highlighting ethnic differences. In summary, almost a quarter of patients with apparently sporadic PPGL in Japan harboured germline variants of the targeted genes. This study reinforces the recommendation in Western guidelines to perform genetic testing for PPGL and genotype-based clinical decision-making in the Japanese population.

A strategy for the determination of the elemental composition by fourier transform ion cyclotron resonance mass spectrometry based on isotopic peak ratios.

We propose a novel strategy for determining the elemental composition of organic compounds using the peak ratio of isotopic fine structure observed by high-magnetic field Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Using 3'-phosphoadenosine 5'-phosphosulfate and CTU guanamine as standard organic compounds, isotopic peaks derived from (15)N-, (34)S-, and (18)O-substituted forms were separated from (13)C-substituted species. Furthermore, these isotopic peaks were quantitatively detected and closely matched the natural abundance of each element. These data successfully led us to determine the one elemental composition in a standard independent manner. The approach should be particularly amenable to the metabolomics research field.

MALDI-MS-based high-throughput metabolite analysis for intracellular metabolic dynamics.

In the present study, a high-throughput analytical method for intracellular metabolites using MALDI-MS has been developed. As an analytical tool, the quantitative performance and dynamic range of MALDI-TOF-MS was confirmed to be suitable for characterizing the trends of intracellular metabolism. The technique was tested by investigating the intracellular metabolism of Escherichia coli by analyzing whole cell samples taken consecutively before and after a perturbation of the environmental carbon source. As the result, dramatic changes of metabolite concentrations responding to the perturbation were observed. The whole analysis process (i.e., sample preparation and MALDI-MS analysis for 24 time points in triplicate) was completed within 4 hours. MALDI-FTICR-MS was used to identify the elemental compositions of detected metabolites to support the reliability of the MALDI-MS-based analysis. The MALDI-MS-based analytical method developed herein should be suitable for high-throughput analysis of dynamic intracellular metabolism events.