Thymic epithelial reticular cell subpopulations in mice defined by monoclonal antibodies

Thymic epithelial reticular cells (TER) are heterogeneous cell populations. Of 14 rat monoclonal antibodies (moAbs) raised against established cell lines of mouse thymic stromal cells (TSC), two were found to recognize TER subpopulations that exhibited distinct intrathymic distributions. MoAb B6TS-1 (IgG2a) recognized the cell-surface determinant mB6TS-1 on TSC in the subcapsular zone, cortico-medullary junction, and medulla. Double staining with antikeratin antiserum showed that, except in the cortex, the distribution of mB6TS-1 bearing cells highly corresponded with that of keratin-positive TER indicating that mB6TS-1 within the thymus was selectively expressed in a particular subpopulation of epithelial cells. Immunoelectronmicroscopy revealed clear polarity in the expression of mB6TS-1 on TER. In the subcapsular zone. TER adherent to fibrous capsule expressed mB6TS-1 on the cell surface that faced the lymphocytes. In the cortico-medullary junction, mB6TS-1 also was found on the side of the TER closely associated with the small blood vessels. The mB6TS-1-bearing cells in the medulla characteristically had cytoplasmic infoldings containing collagen fibrils and amorphous material but did not exhibit the polarity of mB6TS-1-bearing cells. The mB6TS-1-bearing TER were interconnected by desmosomes and tonofilaments, therefore, were easily distinguished from macrophages, dendritic cells, and other components of thymic stroma. In contrast, another moAb AKTS-1 (IgM) stained the keratin-positive TER localized in the subcapsular zone and cortex forming a fine meshwork but did not stain those in the medulla. MoAb B6TS-1 stained thymic nurse cells but not the central cells of thymic rosettes, whereas moAB AKTS-1 did neither. Formation of lymphoid-stromal cell complexes in vitro was not affected by either antibody.     

Renal sodium transport abnormality: Gitelman's syndrome and renal sodium transporter

Recent studies using molecular biological methods have enabled us to identify the genetic abnormality in renal electrolyte metabolism. In renal tubules, diuretic sensitive Na transporter systems are present, and key molecules have been cloned. Thiazide-sensitive Na-Cl contransporter (TSC) is one of the molecules localized in the distal convoluted tubule, whose genetic abnormality causes Gitelman's syndrome (a variant of Bartter's syndrome characterized by dehydration, hypokalemic metabolic alkalosis, secondary aldosteronism lacking hypertension, hypomagnesemia, and hypocalciuria). We identified a mutation in TSC (Leu to Pro change at 623 amino acid position, L623P) in familial Gitelman's syndrome, and we confirmed the loss of TSC function by this mutation in a functional expression system using mammalian cells. This L623P mutation has been found in other patients with Gitelman's syndrome living in the northern part of Japan.     

Inhibitory interaction between the vestibulo-ocular reflexes arising from semicircular canals of rabbits

Summary In anesthetized albino rabbits, electric pulse stimulation was applied to ampullary branches of the vestibular nerve. Reflex discharges evoked from a canal in an extraocular muscle were depressed very effectively by conditioning stimulation at a certain other canal. The present systematic survey revealed that this reflex depression occurred specifically in 3 combinations of conditioning and testing canals; 1. anterior and posterior canals of the same side; 2. anterior and posterior canals of the opposite sides; and 3. horizontal canals of the two sides. Occurrence of postsynaptic inhibition in oculomotor neurons, on the other hand, was indicated by appearance of slow muscle potentials in extraocular muscles. It was confirmed that this motoneuronal inhibition did not contribute to the reflex depression in the above combination (1). Even in combinations (2) and (3), the accompanying motoneuronal inhibition was eliminated by adjusting intensities of canal stimuli or by severing its pathway in the medulla, or it was discriminated from the reflex depression by their different latencies and time courses. Hence, it was concluded that the reflex depression was attributable, at least largely, to non-motoneuronal inhibition, presumably postsynaptic inhibition at relay neurons for vestibulo-ocular reflexes. Slow muscle potentials evoked from a canal were also used as testing responses, but their depression could not be detected after conditioning at other canals.     

Enhancement of an inhibitory input to the feeding central pattern generator in Lymnaea stagnalis during conditioned taste-aversion learning

To study the neuronal mechanism of a conditioned taste-aversion (CTA) learning in the pond snail Lymnaea stagnalis, we examined the synaptic connection between the neuron 1 medial (N1M) cell and the cerebral giant cell (CGC), the former is an interneuron in central pattern generator for the feeding response and the latter is a regulatory neuron to the central pattern generator. Inhibitory postsynaptic potential (IPSP) which was evoked in the N1M cell by activation of the CGC was larger and lasted longer in the conditioned animal than that in the control animal. The electrical properties of the cell body of CGC and the responses of the CGC to the chemosensory inputs were not changed during the CTA learning. These results, together with the previous report indicating the existence of excitatory projection from the N1M cell to the feeding motoneuron, suggest that enhanced IPSP in the N1M cell may underlie the suppression of feeding responses in the Lymnaea CTA learning.     

Modifying effects of 1'-acetoxychavicol acetate (ACA) and the novel synthetic retinoids Re-80, Am-580 and Am-55P in a two-stage carcinogenesis model in female rats

Effects of dietary administration of 1'-acetoxychavicol acetate (ACA) and the novel synthetic retinoids 4-[1-hydroxy-3-oxo-3-(5,6,7,8-tetrahydro-3-hydroxy-5,5,8,8-tetramethyl-2-naphthalenyl)-1-propenyl]benzoic acid (Re-80); 4-[(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthalenyl)carboxamido]benzoic acid (Am-580); and 6-[(3,5-di-tert-butylphenyl) carbamoyl]nicotinic acid (Am-55P) were examined using a two-stage rat carcinogenesis model. A total of 190 female SD rats was treated sequentially with 1,2-dimethylhydrazine (DMH, s.c.); 7,12-dimethylbenz(a)anthracene (DMBA, i.g.); and 2,2'-dihydroxy-di-n-propylnitrosamine (DHPN, in the drinking water) during the first three weeks (DDD-initiation), and an additional 60 rats received the vehicle alone (non-initiation). One week after the completion of the initiation period, they were divided into nine groups and administrated Re-80 (at dose levels of 1.0 or 0.4 ppm), Am-580 (20 or 4 ppm), Am-55P (20 ppm), ACA (100 ppm), all-trans-retinoic acid (10 or 2 ppm) or no supplement in the diet for 33 weeks, until survivors were euthanatized at week 37 weeks. After DDD-initiation, all-trans-retinoic acid at the high dose delayed the development of mammary tumors. The multiplicity of colon tumors in the group fed Am-55P and the incidences of nephroblastomas with ACA or Am-580 were decreased as compared with the control values, but the other chemicals had no modifying effects on tumor development in any organs. Thus, among ACA and the novel synthetic retinoids tested, only Am-55P showed a weak inhibitory effect on a neoplasm of general interest under the present experimental conditions.     

Nitrosative stress in the bronchial mucosa of severe chronic obstructive pulmonary disease

BACKGROUND: Reactive nitrogen species, formed via the reaction of nitric oxide (NO) with superoxide anion and via (myelo)peroxidase-dependent oxidation of NO(2)(-), have potent proinflammatory and oxidizing actions. Reactive nitrogen species formation and nitrosative stress are potentially involved in chronic obstructive pulmonary disease (COPD) pathogenesis. OBJECTIVES: To investigate the expression of markers of nitrosative stress, including nitrotyrosine (NT), inducible NO synthase (iNOS), endothelial NO synthase (eNOS), myeloperoxidase (MPO), and xanthine oxidase (XO) in bronchial biopsies and bronchoalveolar lavage from patients with mild to severe stable COPD compared with control groups (smokers with normal lung function and nonsmokers). METHODS: The expression of NT, iNOS, eNOS, MPO and XO in the bronchial mucosa and bronchoalveolar lavage of patients was measured by using immunohistochemistry, Western blotting, and ELISA and correlated with the inflammatory cell profile. RESULTS: Patients with severe COPD in stable phase had higher numbers of NT(+) and MPO(+) cells in their bronchial submucosa compared with mild/moderate COPD, smokers with normal lung function, and nonsmokers (P < .01). iNOS(+) and eNOS(+) but not XO(+) cells were significantly increased in smokers with COPD or normal lung function compared with nonsmokers (P < .05 and P < .01, respectively). In patients with COPD, the number of MPO(+) cells was significantly correlated with the number of neutrophils (r = +0.61; P < .0025) in the bronchial submucosa. Furthermore, the number of NT(+) and MPO(+) cells was negatively correlated with postbronchodilator FEV(1). CONCLUSION: These data suggest that nitrosative stress, mainly mediated by MPO and neutrophilic inflammation, may contribute to the pathogenesis of severe COPD.     

Transition between two forms of heterochromatin at plant subtelomeres

The manner of packing of the terminal DNA loci into nucleosomes and higher order structures may strongly influence their functional interactions. Besides the structural flexibility of telomeric DNA sequences, conserved features of their chromatin including short nucleosome phasing (157 bp) and nucleosome sliding have been described previously. To gain a complementary knowledge of subtelomeres, we have analysed the chromatin structure of two subtelomeric tandem repeats from the plant Silene latifolia: X43.1 and 15Ssp. X43.1 shows two distinct nucleosome periodicities – 157 and 188 bp. Preferred positions of its two nucleosomes have been mapped at both low and high resolution and the experimental results correspond to computer-predicted positions. 15Ssp is a newly-discovered sequence showing a telomere-associated position by PCR and a subtelomeric location by pulsed-field gel electrophoresis and fluorescence in situ hybridisation. Its 159 bp sequence unit shows a tandem arrangement and the presence of micrococcal nuclease-hypersensitive sites when either naked DNA or chromatin is digested. Use of a chemical nuclease results in a regular nucleosome ladder of 157 bp periodicity. Moreover, 15Ssp mononucleosomes show instability and absence of specific positioning, features typical for telomeric chromatin. This revised version was published online in July 2006 with corrections to the Cover Date.     

High expression of the CD30 molecule in human decidual cells.

CD30 is a receptor-type membrane protein that belongs to the nerve growth receptor superfamily. It is expressed on Hodgkin's cells and activated lymphocytes, as well as in some human malignancies including malignant lymphomas, embryonal carcinomas, and other mesenchymal tumors. However, whether it is expressed in normal tissues remains unclear. To study the expression and biological function of CD30, we first examined various human tissues by immunohistochemistry. The monoclonal antibody Ber-H2 intensely stained the membranes of decidual and endometrial cells with decidual change in frozen sections. Western blots of these tissues with Ber-H2 revealed bands of 120, 105, and 90 kd as found on CD30-expressing cells. Northern blots of these tissues using a CD30 cDNA probe detected mRNAs of the same molecular mass and variety as those in the positive control cell line HUT 102. These results indicated that CD30 is expressed in human endometrial tissue with decidual change and imply that CD30 expression in endometrial tissue is induced by hormonal control.     

Recent progress in electrocardiography

Recent advances in electrocardiography (ECG) have revealed new and useful information concerning the electrophysiologic properties of the normal and diseased heart. 1) Evaluation of the frequency of ventricular premature contractions (VPCs) as a function of underlying heart rate with Holter ECG recordings is a useful approach to elucidate the mechanisms of ventricular arrhythmias and to predict the response of ventricular arrhythmias to antiarrhythmic agents. 2) Decreased heart rate variability, presence of late potential, prolonged QT interval, increased QT interval dispersion, and T wave alternans indicate lethal ventricular tachyarrhythmias and sudden cardiac death. 3) The multiple reentrant wave hypothesis has been widely accepted for the mechanism of atrial fibrillation (AF). Recently, spontaneous initiation of AF by ectopic beats originating from the superior vena cava and the pulmonary veins has been reported. Radiofrequency ablation of the focal source of AF completely prevented the recurrence of AF.