Atrial natriuretic peptide in human urine

Summary A highly sensitive radioimmunoassay to measure atrial natriuretic peptide (ANP) concentration in urine has been established, and its clinical usefulness is presented. ANP in urine was stable at 4° C for several days and was easily measured by our radioimmunoassay. The average ANP excretion in 65 healthy persons was 25.0±1.4 ng/day (mean ± SEM) and the fractional excretion of ANP was 0.7±0.05%. In 14 patients with congestive heart failure, the average ANP excretion was 119.2±29.4 ng/day, which decreased to 53.3±11.0 after successful treatment.Abbreviations ANP atrial natriuretic peptide - hANP human atrial natriuretic peptide - RIA radioimmunoasay - NSB non specific bound - FE_ANP the fractional excretion of atrial natriuretic peptide - FE_Na the fractional excretion of sodium - SIADH the syngrome of inappropriate secretion of antidiuretic hormone     

Interleukin-1 receptor antagonist attenuates airway hyperresponsiveness following exposure to ozone

The role of an interleukin (IL)-1 receptor antagonist (IL-1Ra) on the development of airway hyperresponsiveness (AHR) and airway inflammation following acute O(3) exposure in mice was investigated. Exposure of C57/BL6 mice to O(3) at a concentration of 2.0 ppm or filtered air for 3 h resulted in increases in airway responsiveness to inhaled methacholine (MCh) 8 and 16 h after the exposure, and an increase in neutrophils in the bronchoalveolar lavage (BAL) fluid. IL-1beta expression, assessed by gene microarray, was increased 2-fold 4 h after O(3) exposure, and returned to baseline levels by 24 h. Levels of IL-1beta in lung homogenates were also increased 8 h after O(3) exposure. Administration of (human) IL-1Ra before and after O(3) exposure prevented development of AHR and decreased BAL fluid neutrophilia. Increases in chemokine levels in lung homogenates, tumor necrosis factor-alpha, MIP-2, and keratinocyte chemoattractant following O(3) exposure were prevented by IL-1Ra. Inhalation of dexamethasone, an inhibitor of IL-1 production, blocked the development of AHR, BAL fluid neutrophilia, and decreased levels of IL-1 following O(3) exposure. In summary, acute exposure to O(3) induces AHR, neutrophilic inflammation, epithelial damage, and IL-1. An IL-1Ra effectively prevents the development of altered airway function, inflammation, and structural damage.     

Administration of thyroxine in treated Graves' disease. Effects on the level of antibodies to thyroid-stimulating hormone receptors and on the risk of recurrence of hyperthyroidism

BACKGROUND. Antibodies to thyroid-stimulating hormone (TSH) receptors that stimulate the thyroid gland cause hyperthyroidism in patients with Graves' disease, and their production during antithyroid drug treatment is an important determinant of the course of the disease. One factor that might contribute to the persistent production of antibodies to TSH receptors is stimulation of the release of thyroid antigens by TSH during antithyroid drug therapy. We therefore studied the effect of the suppression of TSH secretion by thyroxine on the levels of antibodies to TSH receptors after thyroid hormone secretion had been normalized by methimazole. METHODS AND RESULTS. The levels of antibodies to TSH receptors were measured during treatment with methimazole, either alone or in combination with thyroxine, in 109 patients with hyperthyroidism due to Graves' disease. The patients first received 30 mg of methimazole daily for six months. All were euthyroid after six months, and their mean (+/- SD) level of antibodies to TSH receptors decreased from 64 +/- 9 percent to 25 +/- 15 percent (P less than 0.01; normal, 2.9 +/- 1.4 percent). Sixty patients then received 100 micrograms of thyroxine and 10 mg of methimazole and 49 received placebo and 10 mg of methimazole daily for one year. In the thyroxine-treated group, the mean serum thyroxine concentration increased from 108 +/- 16 nmol per liter to 145 +/- 11 nmol per liter (P less than 0.01), and the level of antibodies to TSH receptors decreased from 28 +/- 10 percent to 10 +/- 3 percent after one month of combination therapy. In the patients who received placebo and methimazole, the mean serum thyroxine concentration decreased and the level of antibodies to TSH receptors did not change. Methimazole, but not thyroxine or placebo, was discontinued in each group 1 1/2 years after the beginning of treatment. The level of antibodies to TSH receptors further decreased (from 6.6 +/- 3.2 percent at the time methimazole was discontinued to 2.1 +/- 1.2 percent one year later) in the patients who continued to receive thyroxine, but it increased (from 9.1 +/- 4.8 percent to 17.3 +/- 5.8 percent during the same period) in the patients who received placebo. One patient in the thyroxine-treated group (1.7 percent) and 17 patients in the placebo group (34.7 percent) had recurrences of hyperthyroidism within three years after the discontinuation of methimazole. CONCLUSIONS. The administration of thyroxine during antithyroid drug treatment decreases both the production of antibodies to TSH receptors and the frequency of recurrence of hyperthyroidism.     

Lamivudine and IFN-beta sequential therapy in HBe antigen-positive patients with chronic hepatitis B virus genotype C infection.

Sequential treatment with lamivudine and interferon (IFN) has induced sustained biochemical and virologic responses in the majority of patients with chronic hepatitis B in France. However, the efficacy of sequential treatment in patients with chronic hepatitis B virus (HBV) genotype C infection has not been evaluated. Twenty-four HBe antigen-positive patients were treated with 100 mg lamivudine alone for 16-32 weeks, then with both 6 MU IFN-beta and lamivudine for 4 weeks, and lastly with IFN-beta alone for 20 weeks. Sustained response was achieved in 7 (29%) patients 24 weeks after the end of therapy. No lamivudine-resistant variants emerged in any patient. Hepatitis flare occurred in 3 patients after the withdrawal of lamivudine, but none had decompensation. The patients with sustained response were significantly younger at baseline (p = 0.033) and had a significantly lower HBV DNA level at the start of IFN (p = 0.020) than those without sustained response. In conclusion, the rate of response to sequential therapy with lamivudine and IFN in HBe antigen-positive patients with HBV genotype C infection was lower than the rate reported previously. Patients who were young or who had a favorable virologic response to lamivudine were more likely to have a sustained response.     

Stable micro-dystrophin gene transfer using an integrating adeno-retroviral hybrid vector ameliorates the dystrophic pathology in mdx mouse muscle

The ability to transfer the dystrophin gene stably to the skeletal muscle of DMD patients is a major confounding issue in establishing an effective gene therapy for this disease. To overcome this problem, we have examined the ability of muscle fibres from mdx mice to act as in situ factories of retroviral vector production. Tibialis anterior (TA) muscles from 4-week-old mdx mice were injected with an adenoviral vector expressing LacZ within a retroviral expression cassette (AdLZIN). Retroviral vector production was induced by the inclusion of two additional adenoviral vectors expressing retroviral gag-pol (AdGagPol) and 10A1 env genes (Ad10A1). Upon introduction of infected muscles into cell culture, colonies of beta-galactosidase-expressing myotubes formed only in cultures where the muscle was injected with AdLZIN, AdGagPol and Ad10A1, but not from muscle injected with AdLZIN only. Muscles from mdx/nude mice producing retroviral vector displayed a 4.6-fold increase in beta-galactosidase-positive myofibres after 1 month, compared with contralateral muscle in the same animal injected with AdLZIN and AdGagPol only. By constructing a hybrid adeno-retroviral vector expressing a truncated micro-dystrophin construct (AdmicroDyIN), we were able to partially correct the mdx dystrophic phenotype. AdmicroDyIN-mediated expression of micro-dystrophin in mdx TA muscle restored the formation of the dystrophin-associated glycoprotein complex and significantly reduced the level of muscle degeneration over uninjected controls. By stimulating in situ production of retroviral vector expressing micro-dystrophin, we achieved 92%+/-6% transduction of myofibres in the TA muscle by 4 weeks. Strikingly, by 3 months post injection, micro-dystrophin was still expressed to high levels in nearly all the myofibres of the TA muscle. By comparison, there was a pronounced drop in the levels of micro-dystrophin expressed by muscles injected with AdmicroDyIN only. Finally, using a novel PCR approach, we detected reverse-transcribed, integrated proviral sequences in TA muscle genomic DNA by 4 weeks post injection, the levels of which were found to increase after 3 months.     

The blocking effects of omega-conotoxin on Ca current in bovine chromaffin cells

The effects of omega-conotoxin (omega-CgTX) on voltage-sensitive Ca currents (ICa) were studied in cultured bovine adrenal chromaffin cells. A maximal block of ICa of 40-50% was obtained with omega-CgTX in the microM range, and was independent of the holding potential. The onset of block was both concentration- and time-dependent. In bovine chromaffin cells, Ca channels, both sensitive and insensitive to omega-CgTX, appear to be present.     

An interleukin-4-dependent precursor clone is an intermediate of the differentiation pathway from an interleukin-3-dependent precursor clone into myeloid cells as well as B lymphocytes

An interleukin-3-dependent progenitor clone LyD9 and its interleukin-4-dependent derivative clone K-4 were shown to differentiate into myeloid cells as well as B lymphocytes by coculture with bone marrow stroma cells. The K-4 clone is an intermediate between myeloid/lymphoid cells and the LyD9 clone that requires interleukin-4 for differentiation into B lymphocytes and myeloid cells. Granulocyte-macrophage colony stimulating factor-dependent derivatives (LS-1 and K-GM) were also established from induced LyD9 cells. LS-1 and K-GM were myeloid-committed cells.     

Correlation dimension analysis of the artificial circulation

Artificial circulation has been analyzed by decomposing it into parts. However, the sum of the decomposed parts is not equal to the whole system, especially in nonlinear dynamic systems such as biological systems. To evaluate prosthetic circulation as an entity, not as decomposed parts, nonlinear mathematical analytic techniques, including fractal dimension analyzing theory, were used. Two pneumatically actuated ventricular assist devices were implanted as biventricular bypasses (BVB) in chronic animal experiments using four healthy adult goats. For comparison between natural and prosthetic circulation in the same experimental animals, the BVB-type complete prosthetic circulation model with ventricular fibrillation was adopted. All hemodynamic parameters with natural and prosthetic circulation were recorded under awake conditions and calculated by a personal computer system. By the use of nonlinear mathematical techniques, time-series data of the hemodynamics were embedded into the phase space, and correlation dimension analysis was performed to evaluate the reconstructed attractor. Our results suggest that the correlation dimension of the arterial blood pressure does not linearly increase according to the increase of the embedding dimension, even during artificial circulation, suggesting those are the fractal time series data. Dimensional analysis of the hemodynamics revealed that lower dimensional fractal dynamics were observed during prosthetic circulation. Fractal time series data are suggested to have robustness and error resistance. Thus, our results suggest that the circulatory regulatory system with the artificial heart may have these desirable characteristics. Accepted: July 14, 1995     

ASK1 is essential for endoplasmic reticulum stress-induced neuronal cell death triggered by expanded polyglutamine repeats

Expansion of CAG trinucleotide repeats that encode polyglutamine is the underlying cause of at least nine inherited human neurodegenerative disorders, including Huntington's disease and spinocerebellar ataxias. PolyQ fragments accumulate as aggregates in the cytoplasm and/or in the nucleus, and induce neuronal cell death. However, the molecular mechanism of polyQ-induced cell death is controversial. Here, we show the following: (1) polyQ with pathogenic repeat length triggers ER stress through proteasomal dysfunction; (2) ER stress activates ASK 1 through formation of an IRE1-TRAF2-ASK1 complex; and (3) ASK1(-/-) primary neurons are defective in polyQ-, proteasome inhibitor-, and ER stress-induced JNK activation and cell death. These findings suggest that ASK1 is a key element in ER stress-induced cell death that plays an important role in the neuropathological alterations in polyQ diseases.     

Redox-linked signal transduction pathways for protein tyrosine kinase activation

The signaling for activation of protein tyrosine kinases (PTKs) is usually started by binding of ligands to cell-surface receptors. However, recent evidence suggests the presence of ligand binding-independent signaling pathways that are mediated by oxidative stress. Oxidation and reduction of protein cysteine sulfhydryl (SH) groups may work as a molecular switch to start or to stop the signaling. It is known that oxidation of cysteine SH groups on protein tyrosine phosphatases switches off the action of protein tyrosine phosphatases. This event may not, however, signal for initial autophosphorylation of previously unphosphorylated PTKs, whereas it certainly prevents dephosphorylation of once-phosphorylated PTKs. We have suggested new mechanisms for oxidative stress-mediated PTK activation. First, cell-surface glycosylphosphatidylinositol-anchoring proteins and a phosphoglycolipid/cholesterol-enriched membrane microdomain termed a "raft" can be the direct targets of oxidative stress for inducing their clustering through an S-S-bonded or S-X-S-bonded crosslinking of cell-surface proteins and subsequent activation of raft-associating Src family PTKs. Second, intracellular specific cysteine SH groups on PTK proteins can be another target of oxidative stress for inducing a conformational change necessary for initial activation of PTKs. A possible relationship between cell-surface and intracellular events is that the former frequently induces superoxide production as the second messenger for the latter.