CALML5 is a novel diagnostic marker for differentiating thymic squamous cell carcinoma from type B3 thymoma

BACKGROUND

Thymic squamous cell carcinoma and type B3 thymoma are primary neoplasms of the anterior mediastinum that are sometimes difficult to differentiate from one another histologically. However, only a few immunohistochemical markers are available for the differential diagnosis. The purpose of this study was to discover a novel marker for differentiating between thymic squamous cell carcinoma and type B3 thymoma.

METHODS

We used histological samples of thymic carcinomas (n = 26) and type B3 thymomas (n = 38) which were resected between 1986 and 2017. To search for candidates of differential markers, gene expression levels were evaluated in samples using promoter analysis by cap analysis of gene expression (CAGE) sequencing.

RESULTS

Promoter level expression of CALML5 genes was significantly higher in thymic carcinomas than in type B3 thymomas. We further validated the results of the CAGE analysis in all 26 thymic carcinomas and 38 type B3 thymomas by immunohistochemistry (IHC). CALML5 was strongly expressed in the cytoplasm in 19 of 26 cases with thymic carcinoma, whereas positivity at the protein level was shown in two of 38 type B3 thymomas. Thus, the sensitivity (73.1%) and specificity (94.7%) of CALML5 as markers for immunohistochemical diagnosis of thymic carcinoma were extremely high.

CONCLUSION

We identified CALML5 as a potential marker for differentiating thymic squamous cell carcinoma from type B3 thymoma. It is assumed that future clinical use of CALML5 may improve the diagnostic accuracy of differentiating between these two diseases.

Multiple Types of Taste Disorders among Patients with COVID-19

Objective Based on the increasing incidence of smell and taste dysfunction among coronavirus disease 2019 (COVID-19) patients, such issues have been considered an early symptom of infection. However, few studies have investigated the type of taste components that are most frequently affected in COVID-19 patients. This study investigated the difference in frequencies of the types of taste component disorders among hospitalized COVID-19 patients. Methods In this retrospective, single-center, observational study, patients' background characteristics, clinical course, laboratory and radiological findings, and details on taste and/or smell disorders were collected and analyzed from medical records. Patients A total of 227 COVID-19 patients were enrolled, among whom 92 (40.5%) complained of taste disorders. Results Multiple types of taste disorders (hypogeusia/ageusia and hypersensitivity, or hypersensitivity and changing tastes) were reported in 10 patients. In particular, 23 patients reported hypersensitivity to at least 1 type of taste, and 2 patients complained of a bitter taste on consuming sweet foods. Impairment of all taste components was found in 48 patients (52.2%). The most frequent taste disorder was salty taste disorder (81 patients, 89.0%). Hypersensitivity to salty taste was most frequently observed (19 patients, 20.9%). Conclusion Patients with COVID-19 develop multiple types of taste disorders, among which salty taste disorder was the most frequent, with many patients developing hypersensitivity to salty taste. As smell and taste are subjective senses, further studies with the combined use of objective examinations will be required to confirm the findings.

A case of negative-pressure pulmonary oedema after first-time electroconvulsive therapy

Electroconvulsive therapy (ECT) has been used for many years as an important treatment modality in patients with schizophrenia. Recently, many new oral medications have become available to treat schizophrenia. However, ECT remains a valuable therapy for patients who are resistant to oral medications. A 16-year-old girl with schizophrenia was admitted to our hospital with hypoxaemia due to negative-pressure pulmonary oedema (NPPE) after her first ECT. NPPE is an exceedingly rare complication after ECT. However, it can result in serious morbidity if not immediately recognized and treated. This case illustrates the importance of recognizing this rare complication.

Nintedanib inhibits epithelial-mesenchymal transition in A549 alveolar epithelial cells through regulation of the TGF-β/Smad pathway

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic lung disorder. Recent studies have suggested that epithelial-mesenchymal transition (EMT) of alveolar epithelial cells influences development of pulmonary fibrosis, which is mediated by transforming growth factor β (TGF-β). Tumor necrosis factor α (TNF-α), an important proinflammatory cytokine in IPF, has been shown to enhance TGF-β-induced EMT. Nintedanib, a multiple tyrosine kinase inhibitor that is currently used to treat IPF, has been shown to suppress EMT in various cancer cell lines. However, the mechanism of EMT inhibition by nintedanib and its effect on TGF-β and TNF-α signaling pathways in alveolar epithelial cells have not been fully elucidated.

METHODS

A549 alveolar epithelial cells were stimulated with TGF-β2 and TNF-α, and the effects of nintedanib on global gene expression were evaluated using microarray analysis. Furthermore, Smad2/3 phosphorylation was assessed using western blotting.

RESULTS

We found that in A549 cells, TGF-β2 and TNF-α treatment induces EMT, which was inhibited by nintedanib. Gene ontology analysis showed that nintedanib significantly attenuates the gene expression of EMT-related cellular pathways and the TGF-β signaling pathway, but not in the TNF-α-mediated signaling pathway. Furthermore, hierarchical cluster analysis revealed that EMT-related genes were attenuated in nintedanib-treated cells. Additionally, nintedanib was found to markedly suppress phosphorylation of Smad2/3.

CONCLUSION

Nintedanib inhibits EMT by mediating EMT-related gene expression and the TGF-β/Smad pathway in A549 alveolar epithelial cells.

Activation of insulin-like growth factor-1 receptor confers acquired resistance to osimertinib in non-small cell lung cancer with EGFR T790M mutation

Background

Osimertinib (AZD9291) is a third‐generation EGFR‐tyrosine kinase inhibitor (TKI) that selectively inhibits the activating EGFR mutation and T790M mutation, and is currently used globally to treat EGFR‐mutant non‐small cell lung cancer (NSCLC). However, acquired resistance to osimertinib is inevitable.

Methods

We established osimertinib‐resistant cells (PC9/T790M/AZDR and H1975/AZDR) derived from EGFR‐mutant NSCLC cells harboring T790M mutation, and investigated the mechanism of acquired resistance to osimertinib by whole‐exome sequencing and multiple phospho‐receptor tyrosine kinase (RTK) array. A tumor specimen from an EGFR‐mutant NSCLC patient with acquired resistance to osimertinib was also subjected to immunohistochemical analysis.

Results

Whole‐exome sequencing analysis demonstrated that genetic alterations, such as acquisition of EGFR C797S, loss of T790M mutation, MET amplification, or mutated KRAS, MEK, BRAF, PIK3CA, were not detected. Analysis of phospho‐RTK array revealed that insulin‐like growth factor‐1 receptor (IGF1R) was activated in PC9/T790M/AZDR and H1975/AZDR cells. Knockdown of IGF1R by siRNA as well as inhibition of IGF1R activation by linstinib (IGF1R inhibitor) significantly restored the sensitivity to osimertinib. Immunohistochemical analysis revealed that the expression level of phosphorylated IGF1R was higher in the tumor specimen from the EGFR‐mutant NSCLC patient with acquired resistance to osimertinib than in the specimen collected prior to the treatment.

Conclusions

IGF1R activation could occur following treatment with osimertinib in EGFR‐mutant NSCLC with T790M mutation, and might be one of the mechanisms underlying osimertinib resistance. Combined treatment of osimertinib and IGF1R inhibitor might be effective in overcoming the acquired resistance to osimertinib induced by IGF1R activation.

Key points

Significant findings of the study: Using osimertinib‐resistant cells, we found that IGF1R activation induced by osimertinib treatment in EGFR‐mutant NSCLC with T790M mutation is involved in resistance. Increased phosphorylation of IGF1R was observed in the tumor specimen from an EGFR‐mutant NSCLC patient with acquired osimertinib resistance.

What this study adds: IGF1R activation might be one of the mechanisms of osimertinib resistance. A combination therapy with osimertinib and an IGF1R inhibitor might be an optimal approach for overcoming the acquired resistance to osimertinib induced by IGF1R activation.

Malignant Pleural Mesothelioma with Bone Marrow Metastases

A 64-year-old man with the bone marrow metastasis due to malignant pleural mesothelioma (MPM) was diagnosed with anemia, leukoerythroblastosis, thrombocytopenia, and lower back pain. A bone marrow biopsy demonstrated infiltrative malignant mesothelioma lesions in the bone marrow. The patient died within 15 days of the detection of the bone marrow involvement. Physicians should consider performing a bone marrow biopsy to diagnose bone marrow metastasis and treat patients with palliative chemotherapy at an earlier phase of the disease. To our knowledge, this is the first report of an MPM patient having bone marrow metastasis with anemia, leukoerythroblastosis, and thrombocytopenia.

Nanostructured titanium phosphates prepared via hydrothermal reaction and their electrochemical Li- and Na-ion intercalation properties

A series of titanium phosphates with various morphologies are fabricated via a simple hydrothermal reaction of TiO₂ in H₃PO₄ aq.

Glucose-6-Phosphate Dehydrogenase in the Pentose Phosphate Pathway Is Localized in Vanadocytes of the Vanadium-Rich Ascidian, Ascidia sydneiensis samea

Ascidians are sessile marine animals known to accumulate high levels of vanadium selectively in vanadium-containing blood cells (vanadocytes). Almost all the vanadium accumulated in the vacuoles of vanadocytes is reduced to the +3 oxidation state via the +4 oxidation state, although vanadium is dissolved in the +5 oxidation state in sea water. Some of the reducing agents that participate in the reduction have been proposed. By chemical study, vanadium in the +5 oxidation state was reported to be reduced to the +4 oxidation state in the presence of NADPH. The present study revealed the existence of glucose-6-phosphodehydrogenase (G6PDH), the first enzyme to produce NADPH in the pentose phosphate pathway, in vanadocytes of a vanadium-rich ascidian. The results suggested that G6PDH conjugates the reduction of vanadium from the +5 through to the +4 oxidation state in vanadocytes of ascidians.

Benzoate catalysis in the hydrolysis of endo-5-[4'(5')imidazolyl]-bicyclo[2.2.1]hept-endo- 2-yl trans-cinnamate: Implications for the charge-transfer mechanism of catalysis by serine proteases

The acceleration, by a factor of 2500, of the hydrolysis of endo-5-[4'(5')imidazolyl]bicyclo[2.2.1]hept-endo- 2-yl trans-cinnamate by 0.5 M sodium benzoate in 42 mol% dioxane in water can be explained without resort to operation of a "charge-relay" mechanism similar to that often postulated to account for the enzymatic activity of serine proteases. The degree of ionization of 4-methylimidazole and of sodium benzoate in 42 mol% dioxane in water at 60 degrees C have been measured by NMR spectroscopy.

13C enrichment of extracellular neurotransmitter glutamate in rat brain--combined mass spectrometry and NMR studies of neurotransmitter turnover and uptake into glia in vivo

13C-enrichment analysis of glutamate in the extracellular fluid (GLU(ECF): 2-3 microM) by gas-chromatography/mass-spectrometry (GCMS) was combined with in vivo NMR observation of whole-brain GLU (approximately10 mM) to study neurotransmitter uptake. Brain GLU C5 was 13C-enriched by intravenous [2,5-13C]glucose infusion. GLU(ECF) was collected by microdialysis from the cortico-striatal region of awake rats. The 13C-enrichment of basal dialysate GLU C5 during 0.75-1.25 hr of infusion was 0.263 +/- 0.01, very close to the enrichment of whole-brain GLU C5. The result strongly suggests that dialysate GLU consists predominantly of neurotransmitter GLU. For selective 13C-enrichment of neurotransmitter GLU, the whole-brain 13C-enrichment was followed by [12C]glucose infusion to chase 13C from the small glial GLU pool. This leaves [5-13C]GLU mainly in the large neuronal metabolic pool and the vesicular neurotransmitter pool. The uptake of synaptic [5-13C]GLU(ECF) into glia and metabolism to glutamine (GLN) were monitored in vivo by NMR observation of [5-13C,15N]GLN formed during 15NH4Ac infusion. The rate of GLN synthesis, derived from neurotransmitter GLU(ECF) (which provided 80-90% of the substrate) was 6.4 +/- 0.44 micromol/g/hr. Hence, the observed rate represents a reasonable estimate for the rate of glial uptake of GLU(ECF), a process that is crucial for protecting the brain from GLU excitotoxicity.

The first in vivo observation of (13)C-(15)N coupling in mammalian brain

[5-(13)C,(15)N]Glutamine, with (1)J((13)C-(15)N) of 16 Hz, was observed in vivo in the brain of spontaneously breathing rats by (13)C MRS at 4.7 T. The brain [5-(13)C]glutamine peak consisted of the doublet from [5-(13)C,(15)N]glutamine and the center [5-(13)C,(14)N]glutamine peak, resulting in an apparent triplet with a separation of 8 Hz. The time course of formation of brain [5-(13)C,(15)N]glutamine was monitored in vivo with a time resolution of 20-35 min. This [5-(13)C,(15)N]glutamine was formed by glial uptake of released neurotransmitter [5-(13)C]glutamate and its reaction with (15)NH(3) catalyzed by the glia-specific glutamine synthetase. The neurotransmitter glutamate C5 was selectively (13)C-enriched by intravenous [2,5-(13)C]glucose infusion to (13)C-label whole-brain glutamate C5, followed by [(12)C]glucose infusion to chase (13)C from the small and rapidly turning-over glial glutamate pool, leaving (13)C mainly in the neurotransmitter [5-(13)C]glutamate pool, which is sequestered in vesicles until release. Hence, the observed [5-(13)C,(15)N]glutamine arises from a coupling between (13)C of neuronal origin and (15)N of glial origin. Measurement of the rate of brain [5-(13)C,(15)N]glutamine formation provides a novel noninvasive method of studying the kinetics of neurotransmitter uptake into glia in vivo, a process that is crucial for protecting the brain from glutamate excitotoxicity.

Syntheses, structures, stability, and insulin-like activities of peroxovanadium(V) complexes with a heteroligand

Several peroxovanadium(V) complexes were prepared with a tripodal or a quasi-tripodal tetradentate ligand. The structures of K(2)[VO(O(2))(nta)].2H(2)O and K[VO(O(2))(DL-cmhist)].H(2)O have been determined by X-ray crystallography (nta, nitrilotriacetate; cmhist, N-carboxymethylhistidinate). The structure of Cs[VO(O(2))(pda)].2H(2)O (pda, N-pyridylmethyliminodiacetate) has been estimated to be similar to that of K[VO(O(2))(DL-cmhist)].H(2)O. Each complex anion in these compounds adopts a distorted pentagonal bipyramidal structure, which is typical for heptacoordinate oxoperoxovanadium(V) complexes. The peroxide ion binds in a side-on fashion to the vanadium(V) center in the pentagonal plane. The peroxide anion in the cmhist complex dissociates rather easily in an acidic solution (pH approximately 3), while that in the other complexes stays intact under similar conditions. The in vitro insulin mimetic effect of the peroxovanadium(V) complexes has been evaluated by the inhibitory effect on free fatty acid (FFA) release in isolated rat adipocytes treated with epinephrine. The cmhist complex is effective, while the others are almost totally ineffective.

Subunit C of the vacuolar-type ATPase from the vanadium-rich ascidian Ascidia sydneiensis samea rescued the pH sensitivity of yeast vma5 mutants

A vanadium-accumulating ascidian, Ascidia sydneiensis samea, expresses vacuolar-type H(+)-ATPases (V-ATPases) on the vacuole membrane of the vanadium-containing blood cells known as vanadocytes. Previously, we showed that the contents of their vacuoles are extremely acidic and that a V-ATPase-specific inhibitor, bafilomycin A(1), neutralized the contents of the vacuoles. To understand the function of V-ATPase in vanadocytes, we isolated complementary DNA encoding subunit C of V-ATPase from vanadocytes because this subunit has been known to be responsible for the assembly of V-ATPases and to regulate the ATPase activity of V-ATPases. The cloned cDNA was 1443 nucleotides in length, and encoded a putative 384 amino acid protein. By expressing the ascidian cDNA for subunit C under the control of a galactose-inducible promoter, the pH-sensitive phenotype of the corresponding vma5 mutant of a budding yeast was rescued. This result showed that the ascidian cDNA for subunit C functioned in yeast cells.

Exclusive expression of transketolase in the vanadocytes of the vanadium-rich ascidian, Ascidia sydneiensis samea

Ascidians, especially those belonging to the Ascidiidae, are known to accumulate extremely high levels of vanadium in vanadocytes, one type of blood (coelomic) cell. Vanadium, which exists in the +5 oxidation state in seawater, is accumulated in the vanadocytes and reduced to the +3 oxidation state. We have been trying to characterize all of the polypeptides specific to vanadocytes and to specify the proteins that participate in the accumulation and reduction of vanadium. To date, we have localized three enzymes in vanadocytes: 6-phosphogluconate dehydrogenase (6-PGDH: EC 1.1.1.44), glucose-6-phosphate dehydrogenase (G6PDH: EC 1.1.1.49), and glycogen phosphorylase (GP: EC 2.4.1.1), all of which are involved in the pentose phosphate pathway. In the current study, we cloned a cDNA for transketolase, an essential and rate-limiting enzyme in the non-oxidative part of the pentose phosphate pathway, from vanadocytes. The cDNA encoded a protein of 624 amino acids, which showed 61.8% identity to the human adult-type transketolase gene product. By immunocytochemistry and immunoblot analyses, the transketolase was revealed to be a protein that was expressed only in vanadocytes and not in any of the more than ten other types of blood cell. This finding, taken together with the localized expression of the other three enzymes, strongly supports the hypothesis that the pentose phosphate pathway functions exclusively in vanadocytes.

[{Pt]

Prolonged evacuation of [{Pt(CO)(3)}(2)](2+) (1), the first homoleptic, dinuclear, cationic platinum(I) carbonyl complex, results in reversible disproportionation. Complex 1 was formed by dissolution of PtO(2) in concentrated H(2)SO(4) under an atmosphere of CO [Eq. (a)], and completely characterized by NMR ((13)C, (195)Pt), IR, and Raman spectroscopy.

In vivo detection of (15)N-coupled protons in rat brain by ISIS localization and multiple-quantum editing

Three-dimensional image-selected in vivo spectroscopy (ISIS) was combined with phase-cycled (1)H-(15)N heteronuclear multiple-quantum coherence (HMQC) transfer NMR for localized selective observation of protons J-coupled to (15)N in phantoms and in vivo. The ISIS-HMQC sequence, supplemented by jump-return water suppression, permitted localized selective observation of 2-5 micromol of [(15)N(indole)]tryptophan, a precursor of the neurotransmitter serotonin, through the (15)N-coupled proton in 20-40 min of acquisition in vitro at 4.7 T. In vivo, the amide proton of [5-(15)N]glutamine was selectively observed in the brain of spontaneously breathing (15)NH(4)(+)-infused rats, using a volume probe with homogeneous (1)H and (15)N fields. Signal recovery after three-dimensional localization was 72-82% in phantoms and 59 +/- 4% in vivo. The result demonstrates that localized selective observation of (15)N-coupled protons, with complete cancellation of all other protons except water, can be achieved in spontaneously breathing animals by the ISIS-HMQC sequence. This sequence performs both volume selection and heteronuclear editing through an addition/subtraction scheme and predicts the highest intrinsic sensitivity for detection of (15)N-coupled protons in the selected volume. The advantages and limitations of this method for in vivo application are compared to those of other localized editing techniques currently in use for non-exchanging protons.

Localized 15N NMR spectroscopy of rat brain by ISIS

Three-dimensional image-selected in vivo spectroscopy (ISIS), combined with proton-decoupled nuclear-Overhauser-enhanced 15N nuclear magnetic resonance (NMR), was used to localize [15N]metabolites, observed by a head coil, to the brain in rats. In spontaneously breathing anesthetized rats given intravenous [15N]ammonium acetate infusion, brain [5-15N]glutamine was observed in the localized spectrum with a v1/2 of 5 Hz in 19-28 min at 4.7 T, while the signal from blood [15N]urea was eliminated by the localization process. In rats given [15N]leucine infusion, the peak representing predominantly (89%) brain [15N]glutamate was observed, with elimination of the signal from muscle [15N]alanine. In vivo peak areas of the brain [15N]metabolites in the localized spectra were proportional to their concentrations. The advantages and limitations of localization by ISIS using a volume coil with a homogeneous B1 field are compared with those of localization by a surface coil for in vivo 15N NMR study of neurotransmitters in the brain.

A new insulin-mimetic vanadyl complex, (N-pyridylmethylaspartate)oxovanadium(IV) with VO(N2O2) coordination mode, and evaluation of its effect on uptake of D-glucose by Ehrlich ascites tumour cells

Because it has been confirmed that the vanadyl(IV) ion and its complexes act as insulin mimetics, a new organic vanadyl complex, (N-pyridylmethylaspartate)oxovanadium (VOPASP) with VO(N2O2) coordination mode, was prepared. Development of a simple and rapid in-vitro assay is needed for recognition of potent insulin-mimetic complexes. Treatment of Ehrlich ascites tumour cells with 2-deoxyglucose in the presence of vanadyl sulphate, or other vanadyl complexes with the same coordination mode (VOPASP, bis(picolinate)oxovanadium (VOPA) and bis(6-methyl picolinate)oxovanadium (VOMPA)), in the presence of 2-deoxy-D-[1-3H]glucose ([3H]deoxyglucose), resulted in concentration-dependent uptake of 2-deoxyglucose by the cells. The responses of the cells to the vanadyl complexes were reflected, in part, by results obtained from the free fatty acid-releasing assay using rat adipocytes. These results show that the in-vitro assay with Ehrlich ascites tumour cells provides an accurate and rapid assessment of glucose uptake by the cells. The assay is proposed as a means of predicting the insulin-mimetic activity of the vanadyl complexes and for studying the mechanism of action of the complexes.

6-Phosphogluconate dehydrogenase is a 45-kDa antigen recognized by S4D5, a monoclonal antibody specific to vanadocytes in the vanadium-rich ascidian Ascidia sydneiensis samea

We previously prepared a monoclonal antibody, S4D5, specific to vanadocytes, vanadium-containing blood cells, in the vanadium-rich ascidian Ascidia sydneiensis samea. Here, we demonstrate that a 45-kDa antigen recognized by S4D5 is 6-phosphogluconate dehydrogenase (6-PGDH), an enzyme of the pentose phosphate pathway, based on cDNA isolation of RNA samples from blood cells of the ascidian. Western blot analysis confirmed an abundance of 6-PGDH protein in the vanadocytes and localization of 6-PGDH in the soluble extract of the blood cells. Soluble protein exhibited a correspondingly high level of 6-PGDH enzymatic activity. Ascidians are known to selectively accumulate high levels of vanadium in vanadocytes, and the highest recorded concentration of accumulated vanadium is 350 mM, which is 10(7) times the concentration in sea water. Almost all vanadium ions are reduced to the +3 oxidation state via the +4 oxidation state in vanadocytes, indicating that reducing agents must participate in the accumulation. On the other hand, vanadium ions in the +5 oxidation state are reduced to the +4 oxidation state by the presence of NADPH in vitro. Together, these observations suggest that NADPH produced in the pentose phosphate pathway may conjugate the reduction of vanadium from the +5 oxidation state through the +4 oxidation state in vanadocytes of ascidians.

Rate of glutamate synthesis from leucine in rat brain measured in vivo by 15N NMR

The rate of glutamate synthesis from leucine by the branched-chain aminotransferase was measured in rat brain in vivo at steady state. The rats were fed exclusively by intravenous infusion of a nutrient solution containing [15N]leucine. The rate of glutamate synthesis from leucine, determined from the rate of increase of brain [15N]glutamate measured by 15N NMR and the 15N enrichments of brain and blood leucine analyzed by gas chromatography-mass spectrometry, was 0.7-1.8 micromol/g/h at a steady-state brain leucine concentration of 0.25 micromol/g. A comparison of the observed fractional 15N enrichments of brain leucine (0.42 +/- 0.03) and glutamate (0.21 +/- 0.015) showed that leucine provides approximately 50% of glutamate nitrogen under our experimental condition. From the observed rate (0.7-1.8 micromol/g) and the known Km of the branched-chain aminotransferase for leucine (1.2 mM), the rate of glutamate synthesis from leucine at physiological brain leucine concentration (0.11 micromol/g) was estimated to be 0.35-0.9 micromol/g/h, with leucine providing approximately 25% of glutamate nitrogen. The results strongly suggest that plasma leucine from dietary source, transported into the brain, is an important external source of nitrogen for replenishment of brain glutamate in vivo. Implications of the results for treatment of maple-syrup urine disease patients with leucine-restricted diet are discussed.

Glial alkalinization detected in vivo by 1H-15N heteronuclear multiple-quantum coherence-transfer NMR in severely hyperammonemic rat

Brain [5-15N] glutamine amide protons were selectively observed in vivo by 1H-15N heteronuclear multiple-quantum coherence-transfer NMR in spontaneously breathing, severely hyperammonemic rats during intravenous [15N]ammonium acetate infusion and the subsequent recovery period. The linewidth of brain [5-15N]-glutamine amide proton Hz increased from 36 +/- 2 Hz at 3.4 h to 58 +/- 6 Hz after 5.7 h of infusion, a net increase of 22 +/- 6 Hz. Concomitantly, brain ammonia concentration increased from 1.7 to 3.5 +/- 0.2 mumol/g and the rat progressed from grade III to grade IV encephalopathy. On recovery to grade III and decrease of brain ammonia concentration to 1.3 mumol/g, the linewidth returned to 37 +/- 2 Hz. In aqueous solution, [5-15N]glutamine amide proton Hz underwent a 17-Hz linebroadening when pH was raised from 7.1 to 7.5 at 37 degrees C, due to the increased rate of base-catalyzed exchange with water proton. Hence, linebroadening is a sensitive measure of changing intracellular pH. The 22-Hz linebroadening observed in vivo in severely hyperammonemic grade IV rats strongly suggests that the intracellular pH increases from 7.1 to about 7.4-7.5 in astrocytes where glutamine is synthesized and mainly stored. Probable mechanisms for the ammonia-induced alkalinization and decreased intraglial buffering capacity, as well as implications of the result for pathogenesis of hepatic encephalopathy, are discussed.

Severity of hyperammonemic encephalopathy correlates with brain ammonia level and saturation of glutamine synthetase in vivo

Correlation among in vivo glutamine synthetase (GS) activity, brain ammonia and glutamine concentrations, and severity of encephalopathy was examined in hyperammonemic rats to obtain quantitative information on the capacity of GS to control these metabolites implicated in the etiology of hepatic encephalopathy. Awake rats were observed for neurobehavioral impairments after ammonium acetate infusion to attain a steady-state blood ammonia concentration of 0.9 (group A) or 1.3 mumol/g (group B). As encephalopathy progressed from grade III to IV, brain ammonia concentration increased from 1.9 to 3.3 mumol/g and then decreased to 1.3 mumol/g on recovery to grade III. In contrast, brain glutamine concentration was 26, 23, and 21 mumol/g, respectively. NH(4+)-infused rats pretreated with L-methionine DL-sulfoximine reached grade IV when brain ammonia and glutamine concentrations were 3.0 and 5.5 mumol/g, respectively; severity of encephalopathy correlates with brain ammonia, but not glutamine. In vivo GS activity, measured by NMR, was 6.8 +/- 0.7 mumol/h/g for group A and 6.2 +/- 0.6 mumol/h/g for group B. Hence, the in vivo activity, shown previously to increase with blood ammonia over a range of 0.4-0.64 mumol/g, approaches saturation at blood ammonia > 0.9 mumol/g. This is likely to be the major cause of the observed accumulation of brain ammonia and the onset of grade IV encephalopathy.

[Effects of pulmonary rehabilitation in patients with chronic respiratory failure]

To evaluate the effects of pulmonary rehabilitation in patients with chronic respiratory failure, 43 patients with stable chronic respiratory failure were enrolled in a pulmonary rehabilitation program. The program included education, instruction in diaphragmatic breathing, respiratory muscle training, and exercise training (walking and riding a stationary bicycle). Patients were divided into 2 groups by the lowest SpO2 during a 12-minute-walk test done before rehabilitation: lowest SpO2 < 90% (Group A, 32 patients) and lowest SpO2 > or = 90% (Group B, 11 patients). In group A, SpO2 during exercise training was maintained over 90% by O2 inhalation, by load reduction, or by maintaining a slower walking speed. During 2 months of rehabilitation, the distance walked in 12 minutes and the maximum distance walked with an SpO2 > or = 90% significantly increased in both groups, but PaO2, VC, and FEV1 increased only in group A. In group A, the patients with chronic obstructive pulmonary disease had significant increases in PaO2, VC, and FEV1, but those with old tuberculosis sequelae had significant increases in PaO2 only. Pulmonary rehabilitation in patients with chronic respiratory failure may not only increase exercise tolerance but may also improve arterial oxygenation and pulmonary function.

Steady-state in vivo glutamate dehydrogenase activity in rat brain measured by 15N NMR

The in vivo activity of glutamate dehydrogenase (GDH) in the direction of reductive amination was measured in rat brain at steady-state concentrations of brain ammonia and glutamate after intravenous infusion of the substrate 15NH4+. The in vivo rate was determined from the steady-state fractional 15N enrichment of brain ammonia, measured by selective observation of 15NH4+ protons in brain extract by 1H-15N heteronuclear multiple-quantum coherence transfer NMR, and the rate of increase of brain [15N]glutamate and [2-15N]glutamine measured by 15N NMR. The in vivo GDH activity was 0.76-1.17 mumol/h/g, and 1.1-1.2 mumol/h/g at 1.0 +/- 0.17 mumol/g. Comparison of the observed in vivo GDH activity with the in vivo rates of glutamine synthesis and of phosphate-activated glutaminase suggests that, under mild hyperammonemia, GDH-catalyzed de novo synthesis can provide a minimum of 19% of the glutamate pool that is recycled from neurons to astrocytes through the glutamate-glutamine cycle.

Dependence of in vivo glutamine synthetase activity on ammonia concentration in rat brain studied by 1H - 15N heteronuclear multiple-quantum coherence-transfer NMR

The dependence of the in vivo rate of glutamine synthesis on the substrate ammonia concentration was studied in rat brain by 1H-15N heteronuclear multiple-quantum coherence-transfer NMR in combination with biochemical techniques. In vivo rates were measured at various steady-state blood and brain ammonia concentrations within the ranges 0.4-0.55 mumol/g and 0.86-0.98 mumol/g respectively, after low-rate intravenous 15NH4+ infusion (isotope chase). The rate of glutamine synthesis at steady state was determined from the change in brain [5-15N]glutamine levels during isotope chase, observed selectively through the amide proton by NMR, and 15N enrichments of brain glutamine and of blood and brain ammonia measured byN gas chromatography-MS. The in vivo rate (v) was 3.3-4.5 mumol/h per g of brain at blood ammonia concentrations (s) of 0.40-0.55 mumol/g. A linear increase of 1/v with 1/s permitted estimation of the in vivo glutamine synthetase (GS) activity at a physiological blood ammonia concentration to be 0.4-2.1 mumol/h per g. The observed ammonia-dependence strongly suggests that, under physiological conditions, in vivo GS activity is kinetically limited by sub-optimal in situ concentrations of ammonia as well as glutamate and ATP. Comparison of the observed in vivo GS activity with the reported in vivo rates of glutaminase and of gamma-aminobutyrate (GABA) synthesis suggests that, under mildly hyperammonaemic conditions, glutamine is synthesized at a sufficiently high rate to serve as a precursor of GABA, but glutaminase-catalysed hydrolysis of glutamine is too slow to be the sole provider of glutamate used for GABA synthesis.

Selective, in vivo observation of [5-15N]glutamine amide protons in rat brain by 1H-15N heteronuclear multiple-quantum-coherence transfer NMR

The amide protons of [5-15N]glutamine were selectively observed in vivo in the brains of anesthetized, spontaneously breathing rats after intravenous 15NH4+ infusion by 1H-15N heteronuclear multiple-quantum-coherence (HMQC) transfer NMR at 200 MHz for 1H. The peak intensity of the upfield amide proton was proportional to brain [5-15N]glutamine concentration. The 15N-decoupled amide-proton signal was observed in vivo in 2 min of acquisition at a brain [5-15N]glutamine concentration of 7.7 +/- 0.4 mumol/g, in < 8 min at 4.35 +/- 0.15 mumol/g, and in 17-34 min at 2.0 +/- 0.1 mumol/g. 1H signals not coupled to 15N were suppressed by phase cycling. The result suggests that 1H-15N HMQC will be useful for kinetic study of glutamine synthesis in rat brain in vivo at physiological concentrations of brain ammonia.

In vivo activity of glutaminase in the brain of hyperammonaemic rats measured by 15N nuclear magnetic resonance

The in vivo activity of phosphate-activated glutaminase (PAG) was measured in the brain of hyperammonaemic rat by 15N n.m.r. Brain glutamine was 15N-enriched by intravenous infusion of 15NH4+ until the concentration of [5-15N]glutamine reached 6.1 mumol/g. Further glutamine synthesis was inhibited by intraperitoneal injection of methionine-DL-sulphoximine, an inhibitor of glutamine synthetase, and the infusate was changed to 14NH4+ during observation of decrease in brain [5-15N]glutamine due to PAG and other glutamine utilization pathways. Progressive decrease in brain [5-15N]glutamine, PAG-catalysed production of 15NH4+ and its subsequent assimilation into glutamate by glutamate dehydrogenase were monitored in vivo by 15N n.m.r. Brain [5-15N]glutamine (15N enrichment of 0.35-0.50) decreased at a rate of 1.2 mumol/h per g of brain. The in vivo PAG activity, determined from the observed rate and the quantity of 15NH4+ produced and subsequently assimilated into glutamate and aspartate, was 0.9-1.3 mumol/h per g. This activity is less than 1.1% of the reported activity in vitro measured in rat brain homogenate at a 10 mM concentration of the activator Pi. Inhibition by ammonia (brain level 1.4 mumol/g) alone does not account for the observed low activity in vivo. The result strongly suggests that, in intact brain, PAG activity is maintained at a low level by a suboptimal in situ concentration of Pi and the strong inhibitory effect of glutamate. The observed PAG activity in vivo is lower than the reported in vivo activity of glutamate decarboxylase which converts glutamate into gamma-aminobutyrate (GABA). The result suggests that PAG-catalysed hydrolysis of glutamine is not the sole provider of glutamate used for GABA synthesis.

[Effects of inhaled furosemide after indomethacin premedication on bronchial hyperresponsiveness in patients with chronic congestive heart failure]

We studied the effects of inhaled furosemide (40 mg) on bronchial responsiveness to acetylcholine (ACh) in patients with chronic congestive heart failure who had been premedicated with indomethacin (75 mg/day) for five days. The measurement of bronchial responsiveness was performed by inhaling doses of ACh and calculating the provocative concentration of ACh needed to cause a 20% fall in FEV1.0 (PC20-ACh). Inhaled furosemide (N = 11) had no effect on resting pulmonary function but did cause a significant increase in the median value of PC20-ACh, from 7.58 to 11.9 mg/ml (p < 0.01). Irrespective of premedication with indomethacin, inhaled furosemide reduces bronchial hyperresponsiveness to ACh in patients with chronic congestive heart failure. Therefore, we speculate that the mechanism of bronchial hyperresponsiveness noticed in our patients is not related to prostaglandins such as PGE2 or PGI2.

Bronchial hyperresponsiveness to acetylcholine in patients with vasospastic angina pectoris

STUDY OBJECTIVE

To investigate the similarity between coronary vasospasm and bronchial spasm.

DESIGN

Nonrandomized, case-control study.

SETTING

Referral-based clinics for cardiac and pulmonary disease at one secondary care center.

PATIENTS

Seventeen patients with vasospastic angina pectoris (VSAP) and 14 patients with chest pain syndrome (CPS).

INTERVENTIONS

Medications prohibited: those with known effects on bronchial responsiveness.

MEASUREMENT

Induction of coronary vasospasm: ergonovine maleate (10, 20, 40 micrograms) injection into coronary arteries during coronary angiography. Bronchial responsiveness to acetylcholine (ACh): acetylcholine chloride (0.08 to 20 mg/ml) inhalation and calculation of the provocative concentration of ACh (PC20-ACh) that revealed 20 percent fall in FEV1.

RESULTS

The median value for PC20-ACh in patients with VSAP, 7.80 mg/ml, was significantly lower than that in patients with CPS, > 20.0 mg/ml (p < 0.01 by Mann-Whitney U test). The PC20-ACh in patients with VSAP, however, was correlated neither with the responsive threshold of ergonovine maleate, which induced coronary vasospasm, nor with the duration from the latest angina attack.

CONCLUSION

These results suggest that bronchial responsiveness was increased in most patients with VSAP, but not with CPS. We therefore speculate that patients with VSAP may also have hypercontractibility to ACh of noncoronary systemic smooth muscles.

[The appearance and enlargement of localized pulmonary granuloma with eosinophilic infiltration during tuberculosis chemotherapy]

A pulmonary tumorous shadow appeared and enlarged in a 25 years-old male patient undergoing intensive chemotherapy for tuberculosis. The chest X-rays taken on admission revealed effused pleura in the right lung and nodular shadows in the upper area of the right lung. After 40 days of using isoniazid (INH), rifampicin (RFP) and streptomycin (SM), a homogeneous opacity, not previously observed, appeared in the middle area of the right lung (S5). Microscopic examination of the tissues obtained during a transbronchial lung biopsy disclosed epithelioid cell granulomas with marked eosinophilic infiltration. The presence of eosinophilic infiltration due to the admission of antituberculosis agents was disregarded because no change was observed in the new granulomatous shadows during the drug challenge tests and the lymphocyte stimulation test to INH, RFP and SM was negative. Transient aggravation during the initial phase of chemotherapy for pulmonary tuberculosis, such as in this case, is suspected cause by some eosinophilic allergic-induced mechanisms, against bacillary components.

15N n.m.r. measurement of the in vivo rate of glutamine synthesis and utilization at steady state in the brain of the hyperammonaemic rat

The rate of glutamine synthesis and utilization at steady state was measured in vivo in the brains of hyperammonaemic rats by 15N n.m.r. in combination with biochemical techniques. Rats were given an intravenous 15NH4+ infusion at the rate of 4.8 +/- 0.3 mmol/h per kg body wt. for 3.5 +/- 0.2 h, followed by 14NH4+ infusion at the same rate for an additional 5.1 h (chase period). During the chase period, blood ammonia (0.61 +/- 0.015 mumol/g), brain ammonia (2.9 +/- 0.3 mumol/g), glutamate (9.4 +/- 0.8 mumol/g) and glutamine (15N + 14N; 14.4 +/- 1.3 mumol/g) were at steady state. The rate of change in the cerebral [5-15N]glutamine concentration was measured in vivo by 15N n.m.r. at 20.27 MHz. To estimate 15N enrichment of precursor ammonia for glutamine synthetase (GS) in astrocytes which are interposed between cerebral capillaries and neurons, 15N enrichments of blood and brain ammonia were measured by gas chromatography-mass spectrometry. The in vivo rate of glutamine synthesis, which is equal to the rate of glutamine utilization at steady state, was estimated, from the observed rate of change in [5-15N]glutamine concentration and 15N enrichment of brain glutamine, to be 4.8 +/- 1.1 mumol/h per g of brain if 15N enrichment of ammonia at the site of GS in astrocytes is equal to that of blood-borne ammonia, and 13.0 +/- 3.9 mumol/h per g if it is equal to that measured for the whole brain. The observed GS activity in vivo in the brain of the hyperammonaemic rat is 2-5% of the reported optimum activity in vitro measured at enzyme-saturating concentrations of all substrates. The result suggests that substrates and/or cofactors other than ammonia kinetically limit GS activity in vivo. The g.c. chromatogram and mass spectrum of ammonia-derived N-trifluoroacetyl-dibutylglutamate (TAB-glutamate) are shown in Supplementary Publication SUP 50170 (4 pages), which has been deposited at the British Library Document Supply Centre, Boston Spa, Wetherby, West Yorkshire, U.K., from whom copies can be obtained on the terms indicated in Biochem. J.

[Clinical usefulness of newly developed urine protein dipstick (URINE-TP)]

We assessed the clinical usefulness of a newly developed urine protein dipstick (URINE-TP; U-TP) which can detect gamma-globulin and other proteins as well as albumin. Semiquantitative values of urine protein evaluated with U-TP were compared with those evaluated with ordinary urine protein dipsticks (BM-TEST) in 966 urine samples. The two tests showed the same semiquantitative values in 572 of 966 samples (59.2%; Group A). However, U-TP showed a more positive reaction two gradations higher in 89 samples (9.2%; Group B), and showed a more positive value with one gradation higher in 283 samples (29.3%; Group C) compared with BM-TEST. We then measured total protein, alpha 1-microglobulin (alpha 1-M), NAG and beta 2-microglobulin (beta 2-M) in urine, and serum beta 2-M, urea nitrogen (UN) and creatinine (CRE) in both Group A and Group B. In BM-TEST negative patients, urinary total protein, tubular proteins (alpha 1-M, beta 2-M) and NAG were significantly higher (p < 0.01) in Group B than in Group A. Moreover, among patients who had trace or positive results by BM-TEST, serum UN was significantly higher (p < 0.01) in Group B than in Group A. These results suggest that U-TP, a newly developed urine protein dipstick, can detect tubular proteins which cannot be detected by ordinary dipsticks. U-TP may be useful for early detection of renal tubular damage, especially when use is the combined with conventional dipsticks.

A 15N NMR study of in vivo cerebral glutamine synthesis in hyperammonemic rats

Rats were given intravenous 15NH4+ infusion at a rate of 2.2 or 5.5 mmol/h/kg body wt to induce hyperammonemia, as animal models of hepatic encephalopathy. Its effect on cerebral amino acid metabolism was studied in vivo by 15N NMR spectroscopy at 20.27 MHz for 15N. Cerebral [gamma-15N]glutamine (present at a tissue concentration of 4-9 mumol/g) and [alpha-15N]glutamate/glutamine (6 mumol/g) were clearly observed in living rats within 9-18 min. In portacaval-shunted rats, final cerebral [gamma-15N]glutamine concentrations were higher than those in controls after the same infusion period, presumably because decreased 15NH4+ removal in the liver led to increased 15NH3 diffusion into the astrocytes. In control rats, cerebral [gamma-15N]glutamine pool increased at a rate of 1.7 mumol/h/g when blood ammonia concentration was 0.8 mM. 15N enrichment in gamma-15N was 71%. From these observations, in vivo activity of glutamine synthetase in rat brain was estimated to be 3.5 mumol/h/g. Comparison with reported optimum in vitro activity suggests that in situ concentrations of some substrates and cofactors limit the activity of glutamine synthetase in vivo.

[Theophylline toxicity in a patient with status asthmaticus]

A 70-year-old woman was hospitalized for status asthmaticus. The level of CRP was high and chest roentgenogram showed infiltrative shadows in the left middle lung field. Artificial respiration and continuous infusion of methylprednisolone and aminophylline 750 mg/24 hr were performed. Eight hours after admission, seizures suddenly occurred. At this time, brain CT showed no abnormal findings. The seizures were thought to be induced by theophylline toxicity, since serum theophylline concentration was high at 69.9 micrograms/ml. Because theophylline clearance of the patient in a clinically stable condition was normal, it was speculated that theophylline clearance was reduced during status asthmaticus. It is thought that this rare case of theophylline toxicity occurred due to reduction of theophylline clearance during status asthmaticus associated with pneumonia.

Real-time study of the urea cycle using 15N n.m.r. in the isolated perfused rat liver

1. Isolated rat liver was perfused with 10 mM-15NH4Cl, 5 mM-lactate and 1 mM-ornithine, or with 3 mM-[15N]alanine and 1 mM-ornithine, in haemoglobin-free medium. The liver was physiologically stable for over 3 h and synthesized urea at the rate of 1.15 mumol.min-1.g of liver-1 (15NH4(+)-perfused) or 0.41 mumol.min-1.g-1 ([15N]alanine-perfused). 2. The perfused liver was continuously monitored by 15N n.m.r. spectroscopy at 20.27 MHz for 15N. Well-resolved 15N resonances of precursors and intermediates of the urea cycle, present at tissue concentrations of 0.2-3.0 mumol/g, were observed from the intact liver in 5-40 min of acquisition. Key metabolites in liver extract and the final perfusion medium were analysed by n.m.r. and by biochemical assays to determine fractional 15N enrichment and the total 15N recovery. 3. In 15NH4(+)-perfused liver (n = 6), 15N incorporation into glutamate and alanine (1.0-1.3 mumol/g), as well as progressive formation of [15N2]urea, was observed during the first 2 h of perfusion. In the second and third hour, hepatic concentrations of [omega-15N]citrulline and [omega,omega'-15N]argininosuccinate increased to n.m.r.-detectable levels (0.3-0.9 mumol/g). The [15N]aspartate pool was large in the absence of added ornithine, but on its addition was rapidly incorporated into argininosuccinate (n = 3). 4. In [15N]alanine-perfused liver, major metabolites were [15N]glutamate, [gamma-15N]glutamine and [15N]urea. Urea-cycle intermediates were undetectable. 5. The results suggest that, in intact liver provided with excess ammonia, low concentrations of cytosolic argininosuccinate synthetase and argininosuccinate lyase limited the rate of metabolite flux in the urea cycle. By contrast, in alanine-perfused liver at a physiological rate of urea synthesis, mitochondrial carbamoylphosphate synthetase was rate-limiting. 6. The potential utility of 15N n.m.r. for study of metabolite channelling through urea-cycle enzymes in intact liver is discussed.