Evidence for platelet-activating factor receptors in several B lymphoblastoid cell lines

Previous studies have shown that Raji, an Epstein-Barr virus (EBV)-immortalized Burkitt lymphoma B cell line, contains functional platelet-activating factor (PAF) receptors. Twelve other lymphoid cell lines, including Burkitt and non-Burkitt B cell lines, T cell lines, and a non B, non T cell line were tested for the presence of PAF receptors. Radioligand binding studies conducted at 4 degrees C revealed that six lymphoid cell lines of B cell origin (Raji, P3HR-1, BJAB, BJA/HR-1, Dakiki and PB-1) could specifically bind [3H]PAF. Treatment of four (Raji, P3HR-1, Dakiki and PB-1) of the above lymphoid cell lines with PAF resulted in an increase in free intracellular calcium, indicating that these specific PAF binding sites were functional PAF receptors. Other B cell lines (Daudi, B95-8, sfBT, CB-1), T cell lines (MOLT-4, CCRF-CEM) and a non B, non T cell line (NALM-6) had no PAF binding sites and showed no PAF-induced increase in intracellular calcium levels. These studies demonstrate evidence for the presence of PAF receptors on several B lymphocyte cell lines.

[Electrophysiological effects of berbamine on ischemic ventricular tachyarrhythmia]

The effects of berbamine (Ber, 10 mg.kg-1 iv) on ischemic ventricular tachyarrhythmia and electrophysiologic consequences in both normal and ischemic myocardia were studied in the open-chest dogs subjected to programmed electrical stimulation (PES) on 5-8 d after acute myocardial infarction. Its effects were compared with procainamide's (PA). Both drugs distinctly lengthened the QTc interval and the effective refractory period (ERP) of normal and infarct ventricular myocardium, decreased the dispersion of ERP in infarct myocardium (IDR) and the dispersion of ERP in left ventricle (VDR), and increased the diastolic excitability threshold (DET) of normal and infarct ventricular myocardium remarkably. The PES-induced ventricular tachycardia (VT) or ventricular fibrillation (VF) was prevented in 5 out of 6 dogs treated with berbamine and procainamide respectively. (Normal saline did not prevent PES-induced VT or VF). The results suggest that berbamine may be effective in preventing the onset of reentrant ventricular tachyarrhythmia after myocardial ischemic damage.

Role of sulphation in post-translational processing of rat salivary mucins

Segments of rat submandibular salivary gland were incubated in MEM supplemented with 10-800 microM sulphate in the presence of [3H]-glucosamine, [3H]-proline and [35S]-Na2SO4, with 0-8 mM chlorate, an inhibitor of 3'-phosphoadenosine-5'-phosphosulphate formation. Incorporation of glucosamine and sulphate depended upon the sulphate content of the medium and reached a maximum at 400 microM sulphate. The introduction of chlorate into the medium, while having no effect on the protein synthesis as shown by [3H]-proline incorporation, caused, at its optimal concentration of 4 mM, a 90% decrease in mucin sulphation and a 29% drop in mucin glycosylation. At low sulphate content in the medium and in the presence of chlorate the incorporation of sulphate and glucosamine was mainly into the low molecular-weight form of mucin. An increase in sulphate in the medium caused an increase in the high molecular-weight form of mucin and in the extent of sulphation in its carbohydrate chain. This effect of sulphate was, however, inhibited by chlorate. The results suggest that sulphation takes place at an early stage of mucin assembly and that sulphate availability is essential for the formation of the high molecular-weight mucin.

An assay procedure for solubilized thyroid hormone receptor: use of Lipidex

A method using Lipidex-1000 is reported for the assay of thyroid hormone receptor activity. The receptor was extracted from rat liver nuclei, incubated with [125I]T3, and applied to 1-ml disposable pipet tip columns containing a small volume of Lipidex. The resin absorbed the free hormone, and the receptor-bound hormone was recovered in the eluate. The method allowed accurate assay of the receptor activity, satisfying a linear relationship between the activity and the receptor protein concentration. The usefulness of this method was demonstrated by determining the pH optimum and the Kd and Bmax of T3 binding by the receptor. The Lipidex column can be used for the preparation of an unoccupied receptor after dissociation of the endogenously bound hormone.

[The preparation and properties of catechol-1,2-dioxygenase from Pseudomonas putida]

Catechol-1,2-dioxygenase (EC 1.13.11.1) catalyzes the degradation of catechol to cis, cis-muconic acid. The biochemical properties of catechol-1,2-dioxygenase from Pseudomonas putida 84103 were investigated. The optimum pH and temperature is 7.5-8.0 and 25-30 degrees C, respectively. Cu2+, Zn2+ inhibit the enzyme activity. The paper chromatograph and UV absorption spectrum of enzymatic reaction product are accordance with those of the standard muconic acid.

Immunological abnormalities in HTLV-I-associated myelopathy: spontaneous release of interleukin-2 and interleukin-2 receptor by peripheral blood lymphocytes

Ten patients with human T lymphotropic virus type I-associated myelopathy (HAM), 5 asymptomatic HTLV-I carriers and 11 healthy normal volunteers were studied to determine if peripheral blood lymphocytes spontaneously release IL-2 and soluble IL-2 receptors. Peripheral blood lymphocytes obtained from HAM patients proliferated spontaneously when cultured for 5 days in vitro. Proliferating cells were CD3+ lymphocytes and both CD4+ cells and CD8+ cells as shown by morphologic and immunohistochemical observations. These T cell responses were also found in asymptomatic carriers, but the responses were not as marked as those of HAM patients. IL-2 activity in the culture supernatants was much higher in HAM patients than in asymptomatic carriers; IL-2 activity correlated well with the intensity of spontaneous proliferation of lymphocytes. Furthermore, soluble IL-2 receptors in the cell-free supernatants from HAM patients were markedly increased compared to those from asymptomatic carriers. These results indicate that spontaneous proliferation of T cells is intimately related to HTLV-I infection and is probably due to autocrine or paracrine pathways which involve IL-2 and IL-2 receptor system.

Transforming growth factor-beta 1 (TGF-beta 1) is a bifunctional immune regulator for mucosal IgA responses

Porcine transforming growth factor-beta 1 (TGF-beta 1) exerts a unique bifunctional immunoregulatory effect on IgA responses in murine mesenteric and Peyer's patches lymphocyte cultures. TGF-beta 1 is a potent costimulator of LPS-induced IgA responses. The enhancement was observed at TGF-beta 1 at 0.1 to 10 ng/ml in both early and late phases of IgA responses from Day 5 to Day 14 in cultures. On the contrary, TGF-beta 1 exerts a profound immunosuppressive effect on IL-5-induced IgA synthesis. TGF-beta 1 is a natural cytokine produced by intestinal epithelial cells and may account for the polyclonal production and secretion of IgA at the mucosal surface and ensure the integrity of the primary host defense by mucosa-associated lymphoid tissues (MALT).

[The changes of beta-glucuronidase in rabbit model with calcium bilirubinate stone]

The aim of the present study is to determine the beta-glucuronidase changes in bile and hepatobiliary tissue of rabbit model having pigment gallstone by means of biochemical and enzymehistochemical assay methods. The result showed both of the bacterial and non-bacterial beta-glucuronidase take part in the course of pigment gallstone formation. The bacterial beta-glucuronidase level increased quickly before the formation of gallstone, then decreased with control of bacterial infection. Non-bacterial beta-glucuronidase increased slowly in pro-formation stage of gallstone, then kept high level for long period of time. The relationship between beta-glucuronidase and pigment gallstone formation is also discussed.

Motoneurons innervating the external anal and urethral sphincters of the female cat have different patterns of dendritic arborization

The locations and dendritic arbors of sacral motoneurons (MNs) innervating the striated external anal and urethral sphincters (EAS and EUS, respectively) of the cat were investigated using muscle injections of cholera toxin-conjugated HRP (CT-HRP). Serial reconstructions showed that all cells labelled after EAS injections were located in the dorsomedial (DM) subdivision of Onuf's nucleus, whereas all cells labelled from the EUS were located in the ventrolateral (VL) subdivision. The dendritic arbors of EAS and EUS MNs were very different, suggesting differences in afferent control. In addition, prominent bundles of dendrites extended preferentially into the regions occupied by functionally appropriate preganglionic neurons (PGNs) in the sacral parasympathetic nucleus (SPN) which innervate the colon and bladder.

[Diterpenoid constituents in bulbs of Fritillaria anhuiensis S.C. Chen et S.F. Yin]

The bulb of Fritillaria anhuiensis, a substitute for the traditional Chinese medicine Beimu, has been used as antibechic and expectorant. From the either soluble part of the bulb, four constituents were isolated and identified by spectral analysis (IR, MS, 1HNMR, 13CNMR) as beta-sitosterol, daucosterol, ent-kaur-15-en-17-ol and ent-kauran-16 beta, 17-diol.

[Influence of iron deficiency anemia on development of thymus and spleen and adenosine deaminase activity in rats]

Models of rats with iron deficiency anemia (IDA) were established, and changes in development of the thymus and spleen and adenosine deaminase (ADA) activity in them studied. The size and weight of the thymus in IDA rats were decreased, which suggested that the development of the thymus was lowered; but the size and weight of the spleen in IDA group were increased. ADA activities of the thymus and the spleen in IDA rats were significantly decreased by 32.98% and 25.89%, respectively. One week after iron supplement, the weight of the thymus and spleen in IDS group returned to normal level (P greater than 0.05), and their ADA activity also significantly increased, but ADA activity of the thymus tissue did not return to the normal. The results suggested that the changes in ADA activity of the thymus and spleen tissues were related to iron deficiency. Stepwise regression analysis suggested that there was a negative correlation between ADA activity of the thymus tissue and FEP/Hb ratio.

[Effects of alpha-adrenoceptor agonists on cardiac function and blood pressure in rats]

In rat working hearts, alpha 1-adrenoceptor agonist phenylephrine increased LVP, +/- dP/dtmax, ABF and HR in the presence of propranolol. But alpha 2-adrenoceptor agonist B-HT 920 was ineffective. The changes induced by phenylephrine were antagonized by prazosin. In normotensive pithed rats, iv methoxamine dose-dependently increased LVP, +/- dP/dtmax, LVEDP, SAP and DAP. The changes in haemodynamics elicited by iv methoxamine were also antagonized by pretreatment with prazosin, and were attenuated by nifedipine (1 mg/kg, ia). In these two experiments, the increase in HR developed more slowly. The results suggest that postjunctional alpha 1-adrenoceptors, which exist in rat myocardium, produce a positive inotropic effect, which is possibly dependent on influx of extracellular calcium. Postjunctional alpha 2-adrenoceptors-mediated effects were not found in rat myocardium in our functional studies.

Identification of functional platelet-activating factor receptors in Raji lymphoblasts

The binding and metabolism of platelet-activating factor (PAF) were characterized in Raji, a human Burkitt's lymphoma-derived cell line. Raji lymphoblasts readily metabolized PAF by deacetylation-reacylation at 37 degrees C, but not at 4 degrees C. Binding studies conducted at 4 degrees C demonstrated specific binding that reached saturation within 80 min. This binding was only partially reversible. Scatchard analysis of PAF binding data revealed a single class of PAF binding sites (17,800 +/- 3,600/cell) with a K of 2.3 +/- 0.3 nM. These high-affinity PAF binding sites were shown to be functional receptors, as 100 pM to 1 microM PAF increased free intracellular calcium in a dose-dependent manner. The dose of PAF necessary to achieve half maximal calcium mobilization response was 6.3 nM, which was in the range of the K for the receptor calculated from the binding studies. The structurally dissimilar PAF receptor antagonists CV-3988 and BN52021 inhibited the PAF-induced calcium changes at doses that competed with PAF binding. These studies provide the first evidence for a functional PAF receptor expressed on a lymphocyte cell line.

Identification of functional platelet-activating factor receptors in Raji lymphoblasts

The binding and metabolism of platelet-activating factor (PAF) were characterized in Raji, a human Burkitt's lymphoma-derived cell line. Raji lymphoblasts readily metabolized PAF by deacetylation-reacylation at 37 degrees C, but not at 4 degrees C. Binding studies conducted at 4 degrees C demonstrated specific binding that reached saturation within 80 min. This binding was only partially reversible. Scatchard analysis of PAF binding data revealed a single class of PAF binding sites (17,800 +/- 3,600/cell) with a K of 2.3 +/- 0.3 nM. These high-affinity PAF binding sites were shown to be functional receptors, as 100 pM to 1 microM PAF increased free intracellular calcium in a dose-dependent manner. The dose of PAF necessary to achieve half maximal calcium mobilization response was 6.3 nM, which was in the range of the K for the receptor calculated from the binding studies. The structurally dissimilar PAF receptor antagonists CV-3988 and BN52021 inhibited the PAF-induced calcium changes at doses that competed with PAF binding. These studies provide the first evidence for a functional PAF receptor expressed on a lymphocyte cell line.

Hyperthyroid adult rat cardiomyocytes. II. Single cell electrophysiology and free calcium transients

The effects of hyperthyroidism on electrophysiological properties and intracellular free calcium transients in single adult rat cardiomyocytes were studied using conventional microelectrodes and time-resolved single cell fura-2 fluorescence microscopy. Under control conditions, resting membrane potentials and triggered action potentials were not different in euthyroid and hyperthyroid myocytes. Calcium transients produced by electrical stimulation, however, were markedly abbreviated in hyperthyroid myocytes. During a train of stimuli, the duration of the calcium transients at half peak amplitude (half time) was 124 +/- 14 ms at the fifth beat in hyperthyroid cells vs. 287 +/- 35 ms in euthyroid cells. Isoproterenol (1 microM) prolonged time to 50% repolarization (APD50) of the action potentials and increased the peak calcium transients in both euthyroid and hyperthyroid myocytes. It also shortened the half time of the calcium transients in euthyroid myocytes but had little effect on the half time in hyperthyroid cells. These data are consistent with the electrophysiology and mechanical performance in intact euthyroid and hyperthyroid cardiac tissues, and the intrinsic changes in hyperthyroid tissues can therefore be illustrated in single ventricular myocytes. Furthermore, the results suggest that alterations in intracellular calcium handling by sarcoplasmic reticulum may account for contractile changes of the heart induced by hyperthyroidism.

Lateral diffusion in the plasma membrane of maize protoplasts with implications for cell culture

Plasma-membrane dynamics in live protoplasts from maize (Zea mays L.) roots were characterized and examined for relationships as to the ability of the protoplasts to synthesize new cell walls and develop to cells capable of division. The lateral diffusion-coefficients and mobile fractions of fluorescence-labeled plasma-membrane proteins and lipids were measured by fluorescence photobleaching recovery. Small but significant effects on the diffusion of membrane proteins were observed after treatments with oryzalin or amiprophosmethyl, microtubule-disrupting drugs that increased the mobile fraction, and after treatments with cytochalasins B or D, microfilament-disrupting drugs that decreased the diffusion coefficient. A number of parameters were tested for correlative effects on membrane dynamics and protoplast performance in culture. Protoplasts isolated with a cellulase preparation from Trichoderma viride showed faster membrane-protein diffusion and a lower frequency of development to cells capable of division than did protoplasts isolated with a cellulase preparation from T. reesei. Membrane proteins in maize A632, a line less capable of plant regeneration from callus, diffused with a smaller diffusion coefficient but a greater mobile fraction than did membrane proteins in maize A634, a line with greater regeneration capacity. The plasma membranes of A632 and A634 protoplasts also differed with regard to lateral-diffusion characteristics of phospholipid and sterol probes, although the presence of both rapidly and slowly diffusing lipid components indicated the apparent existence of lipid domains in both A632 and A634. The protoplasts of the two lines did not differ significantly, however, in either wall regeneration or frequency of development to cells capable of division.

Vasoactive intestinal peptide (VIP) may reduce the removal rate of cytosolic Ca2+ after transient elevations in clonal rat lactotrophs

The prolactin-producing rat anterior pituitary GH4C1 cells possess Ca2+-activated K channels which are activated by physiological elevations of the cytosolic Ca2+ concentration even at membrane potentials more negative than the normal level of about -50 mV. Whole-cell current recordings showed a marked outward tail current following depolarizing voltage steps to 0 mV from a holding potential close to the normal membrane potential. The half-time of this tail current was about 1.3 s after a 4-s depolarization step. The GH4C1 cells also possess voltage-activated Ca channels, and we conclude that this tail current is a Ca2+-activated K+ current for the following reasons: (1) The reversal potential for the tail current was close to the K+ equilibrium potential for a range of transmembrane K+ gradients. (2) The tail current was blocked by a Ca2+ antagonist, and the voltage dependence of this current closely mirrored the voltage dependence of the isolated Ca2+ current. The time-course of the decline of the tail current thus reflects the removal rate of the Ca2+ entering the cytosol through voltage-dependent Ca channels during the depolarizing voltage step. VIP stimulates prolactin secretion from GH4C1 cells, and this peptide prolonged the half-time of the tail current by about 47% in 63% of the cells. This indicates that VIP may prolong the transient cytosolic Ca2+ elevations following the action potentials in these cells. Such a mechanism might be an important factor for the control of the cytosolic Ca2+ level, and hence hormone secretion.

Energy depletion-repletion and calcium transients in single cardiomyocytes

Rapid fluctuations of intracellular free calcium in single adult rat heart myocytes were monitored by time-resolved fura-2 fluorescence microscopy. Under controlled aerobic conditions (35 degrees C, pH 7.3), electrical stimulation at 0.5 Hz produced a concave negative staircase of calcium transients. When the myocytes were challenged with 3 mM amobarbital (Amytal) and 2 microM carbonyl cyanide m-chlorophenylhydrazone (CCCP) to deplete ATP, the cells became unresponsive to electrical stimulation within 1 min but responded to 10 mM caffeine with a large increase in free calcium. After the development of rigor contracture, the cellular response to caffeine was blunted. Free calcium increased at a variable rate in individual cells, reaching values of 300-1,000 nM after 15 min. When the inhibitors were removed, calcium declined toward control values, and spontaneous contractile activity and calcium transients were invariably observed. During subsequent electrical stimulation, there was a decrease in the half-widths of the calcium transients and an attenuation of the negative staircase. Parallel experiments with cells in suspension indicated that Amytal and CCCP caused ATP to fall from 27.6 +/- 1.6 to 0.7 +/- 0.2 nmol/mg protein, and the percent rod-shaped cells to fall from 70 to 0% in 5 min. Removal of the inhibitors after 15 min caused a rebound in ATP to 5.3 +/- 1.5 nmol/mg within 2 min and 6.6 +/- 1.3 nmol/mg after 10 min.

[Protective effects of berberine on spontaneous ventricular fibrillation in dogs after myocardial infarction]

The effects of berberine (Ber 5 mg/kg iv) on ventricular tachyarrhythmias and electrophysiologic consequences in both normal and ischemic myocardium were studied in the open-chest dogs subjected to programmed electrical stimulation (PES) and intimal surface anodal direct current stimulation of the circumflex coronary artery on 5-8 d after acute myocardial infarction. Its effects were compared with procainamide (PA). Both drugs distinctly lengthened the QTc interval and the effective refractory period (ERP) of normal and infarct myocardium in both ventricles and decreased the dispersion of ERP in infarct myocardium (IDR) as well as the dispersion of ERP in left ventricle (VDR). The PES-induced ventricular tachycardia (VT) or ventricular fibrillation (VF) was prevented in 4 out of 6 Ber treated and 5 out of 6 PA treated dogs. Ber prevented spontaneous VF in 4 dogs (n = 5). PA prevented spontaneous VF in 3 dogs (n = 5). Normal saline (NS) did not prevent PES-induced VT/VF and spontaneous VF. The results suggest that Ber may be effective in preventing the onset of reentrant ventricular tachyarrhythmias and sudden coronary death after myocardial ischemic damage.

[Screening of strains producing extracellular catechol 1,2-dioxygenase and fermentation conditions]

Two strains of Pseudomonus sp. having the extracellular catechol 1, 2-dioxygenase activity were selected from 112 bacterial strains. The conditions for enzyme production of the strains were examined. The optimal temperature and pH for enzyme formation were 30 degrees C and pH 6.8-7.0 respectively. Enzyme formation was enhanced by sodium benzoate, and was markedly inhibited by glucose, maltose and glycerol. Ammoniacal nitrogen sources were essential for cell growth and enzyme production. Sodium succinate was an effective inducer for enzyme formation. When the organism was grown in 0.15% sodium benzoate medium (pH 6.8-7.0) at 30 degrees C for 72 hours, about 10 units of catechol 1,2 dioxygenase per ml was obtained.

Fluorescence and Delayed Light Emission from Mesophyll and Bundle Sheath Cells in Leaves of Normal and Salt-Treated Panicum miliaceum

A modified fluorescence microscope system was used to measure chlorophyll fluorescence and delayed light emission from mesophyll and bundle sheath cells in situ in fresh-cut sections from leaves of Panicum miliaceum L. The fluorescence rise in 3-(3,4-dichlorophenyl)-1, 1-dimethylurea (DCMU)-treated leaves and the slow fluorescence kinetics in untreated leaves show that mesophyll chloroplasts have larger photosystem II unit sizes than do bundle sheath chloroplasts. The larger photosystem II units imply more efficient noncyclic electron transport in mesophyll chloroplasts. Quenching of slow fluorescence also differs between the cell types with mesophyll chloroplasts showing complex kinetics and bundle sheath chloroplasts showing a relatively simple decline. Properties of the photosynthetic system were also investigated in leaves from plants grown in soil containing elevated NaCl levels. As judged by changes in both fluorescence kinetics in DCMU-treated leaves and delayed light emission in leaves not exposed to DCMU, salinity altered photosystem II in bundle sheath cells but not in mesophyll cells. This result may indicate different ionic distributions in the two cell types or, alternatively, different responses of the two chloroplast types to environmental change.

Studies of beta-thalassemia mutations in families living in three provinces in southern China

beta-Thalassemia is a common disease in Southern China and 10 different mutations or frameshifts are responsible for most types of beta-thalassemia in this area. We studied 126 chromosomes of 80 beta-thalassemia patients from the Guangxi, Guangdong, and Sichuan Provinces using the polymerase chain reaction followed by dot-blot hybridization with specific oligonucleotide probes. The most common mutation in the three provinces is the frameshift at codons 41-42, followed by the A----T mutation at codon 17. The A----G mutation at nt -29 of the promoter is common in Sichuan but not in the other two provinces. Three mutations (T----C at nt -30; G----T at IVS-I-1, and G----C at IVS-I-5) were not observed. These data were used to initiate a prenatal diagnosis program using the same techniques for identification. Eleven fetuses at risk for beta-thalassemia have been diagnosed.

Cisapride in gastro-oesophageal reflux disease: effects on oesophageal motility and intra-oesophageal pH

Since gastro-oesophageal reflux disease is due to disturbances of oesophageal motility, motor and pH measurements are an important means to test a new anti-reflux drug, cisapride. In oesophageal manometry cisapride increased the pressure of the lower oesophageal sphincter in healthy volunteers and patients, and in the majority of studies it also strengthened the amplitude of oesophageal contractions. Cisapride lowered the total duration of acid exposure in the lower oesophagus in both volunteers and reflux patients. Thus cisapride may be useful in the treatment of gastro-oesophageal reflux disease.

[Immunohistochemical study of alpha-1-antichymotrypsin and GFAP in glioma]

GFAP is a specific antigen of glial element, but Alpha-1-antichymotrypsin has not been reported in the literature Alpha-1-antichymotrypsin was guided by GFAP using PAP method to the astrocytes of 137 gliomas. 120 (87%) gliomas were positive for Alpha-1-antichymotrypsin. Of these 120 gliomas, 86 (72%) gave diffuse distribution, 17 (14%) gave focal distribution, and 17 (14%) gave scattered distributions. Alpha-1-antichymotrypsin in glioma tissue may be an important tumor marker for diagnosis.