The effect of individual HLA-A and -B mismatches on the generation of cytotoxic T lymphocyte precursors

In order to study the correlation between HLA mismatches and the cytotoxic T lymphocyte precursor frequency, we used a limiting dilution analysis to determine the CTLp frequencies against individual mismatched HLA-A and -B alloantigens in 21 patients waiting for a renal transplant. Altogether, thirty-three mismatched HLA-A antigens and 55 HLA-B antigens were tested. The CTLp frequencies against mismatches of HLA-B locus antigens were found to be significantly higher than those against HLA-A antigens (P less than 0.002). This may explain why matching for HLA-B antigens is more important for a good renal allograft survival than matching for HLA-A antigens.

Post-translational modification of a monocyte-specific chemoattractant synthesized by glioma, osteosarcoma, and vascular smooth muscle cells

Chemotaxis is an important step in monocyte recruitment in inflammation, wound healing, and tumor growth. We reported previously that monocyte chemotactic activity secreted by malignant cells and normal smooth muscle cells is associated with a protein or family of proteins that are related to the monocyte-specific smooth muscle cell-derived chemotactic factor (SMC-CF) (Graves, D. T., Jiang, Y. L., Williamson, M. J., and Valente, A. J. (1989) Science 245, 1490-1493). Similar monocyte chemotactic proteins (MCP-1) produced by U-105MG human glioma cells have also been identified (Yoshimura, T., Robinson, E. A., Tanaka, S., Appella, E., Kuratsu, J., and Leonard, E. J. (1989) J. Exp. Med. 169, 1449-1459). We now report that the MCP-1 gene is expressed in MG-63 human osteosarcoma and vascular smooth muscle cells and that SMC-CF antiserum specifically immunoprecipitates proteins synthesized by U-105MG glioma cells. Experiments were undertaken to elucidate the processing pathway of MCP-1/SMC-CF-like proteins in each of these cell types. These experiments demonstrate that larger MCP-1/SMC-CF-like proteins are derived from a Mr = 9000 precursor. Post-translational modification involves the addition of O-linked carbohydrates and sialic acid residues. Differences in carbohydrate processing account for the heterogeneity in MCP-1/SMC-CF-like proteins produced by different cell types. Secretion of these proteins occurs rapidly following processing events in the endoplasmic reticulum-Golgi compartment.

[Establishment of standard strains of serotypes (groups) of Streptococcus pneumoniae in China]

Streptococcus pneumoniae is an important human pathogen which is responsible for life-threatening infections such as pneumonia, bacteremia and meningitis as well as for less severe but highly prevalent diseases such as otitis media and sinusitis. The number of serogroups (types) of Streptococcus pneumoniae found in the world is total 46 groups or 83 types according to typing system of Statens Serum Institute, Copenhagen, Denmark. The standard strains established in our lab of 42 groups or 67 types distributed in 17 different regions in China. The significance of this study is that two of the new serotypes (10C, 16A) are first reported in the literature in which the microbes were the agents causing pneumococcal infections. Our standard strains also include some serotypes on rare occasions such as 19C and 22A and 33C which have been found only in Asia. Our findings not only increase the total number of known types of pneumococci from 83 to 85, but also indicate that China has made progress in the field of pneumococcal research. It is the first time to report establishing a series of standard strains of pneumococci involving many serotypes (groups) in China. The work is necessary as a preliminary for pneumococcal disease prevention and treatment. The standard strains listed here with providing the resource of strain and scientific basis for developing vaccine and biological products.

Relation between plasma atrial natriuretic peptide (ANP) and glomerular ANP receptors in 5/6 nephrectomized rats

Chronic renal failure (CRF) was induced in male wistar rats (Group I) by 5/6 nephrectomy and the sham-operated ones served as control (Group II). The results showed that in Group I, plasma atrial natriuretic peptide (ANP) levels increased progressively as the Scr was elevated. Plasma R-A rose simultaneously compared to the normal (P less than 0.001). At the 20th week after operation, urine volume and Na decreased significantly (P less than 0.05). The number of glomerular receptors decreased markedly at the 12th week (P less than 0.05) and 20th week (P less than 0.01). Our data suggest that in 5/6 nephrectomized rats, the elevation of plasma ANP level might be partly caused by the damage of glomerular ANP receptors, and the elevated plasma ANP could not play its role in diuresis, natriuresis, blood pressure depression and R-A inhibition as a result of the damage of kidney ANP receptors.

Whole-cell patch study of GABAergic inhibition in CA1 neurons of immature rat hippocampal slices

Inhibitory processes mediated by gamma-aminobutyric acid (GABA) were studied in immature rat hippocampal slices using the whole-cell patch clamp technique. Orthodromically evoked hyperpolarizing inhibitory postsynaptic potentials (IPSPs) were observed in CA1 neurons of postnatal 2-5 (P2-5) and 7-13 (P7-13) day old rats under conditions of low internal [Cl-]. In the whole-cell voltage-clamp mode, applications of GABA evoked outwards currents which reversed at -55 mV and -62 mV in P2-5 and P7-13 CA1 neurons, respectively, with comparable reversal potential for the IPSPs for each age. An increase in internal [Cl-] caused a depolarizing shift of the GABA reversal potential which followed the Nernst equation. In both groups of neurons, the IPSPs and GABA currents were blocked with the bath applications of bicuculline (10 microM) and picrotoxin (100 microM). We conclude that the GABAA-mediated inhibitory synaptic process exists in P2-5 CA1 neurons and hypothesize that the absence of such IPSPs noted in previous studies of immature CA1 neurons was likely due to higher internal [Cl-] in the more immature neurons.

Potential of hypertonic medium treatment for embryo micromanipulation: II. Assessment of nuclear transplantation methodology, isolation, subzona insertion, and electrofusion of blastomeres to intact or functionally enucleated oocytes in rabbits

The objective of this research was to study efficiency of embryo development following transfer of blastomeres into the perivitelline space of oocytes. Single blastomeres from 8-, 16-, and 32-cell embryos were obtained following mucin coat and zona pellucida removal by combined treatments with pronase and acidic phosphate-buffered saline (PBS, pH = 2.5). Blastomeres were separated by pipetting with a fire-polished micropipette following incubation in Ca+(+)-free PBS for 15 min at 39 degrees C. This procedure resulted in over 97% blastomere separation. For ease of blastomere insertion, oocytes were placed in droplets of 0.5 M sucrose in PBS (SPBS) during micromanipulation. To functionally enucleate oocytes some were stained with Hoechst 33342 DNA stain and irradiated. A single 8- or 16-cell blastomere was aspirated into an injection pipette (35 microns or 25 microns at the tip, respectively) and inserted into the perivitelline space of an irradiated or non-irradiated oocyte, but not fused with the oocyte. This micromanipulation procedure did not affect development of individual blastomeres into blastocysts or trophectoderm vesicles when compared with cultured control single blastomeres (P greater than .05). When the inserted blastomere was induced to fuse with an intact non-irradiated oocyte under an electric field, 56-57% were fused and 39-45% of the fused and activated oocytes developed to morulae or blastocysts. When an inserted blastomere (from 8-32-cell embryos) was induced to fuse with a functionally enucleated oocyte treated by Hoechst 33342 staining, followed by washing and UV-light irradiation, 63-66% of them were fused, but only 15-22% developed to the morula or blastocyst stage. This research demonstrated that the use of hypertonic medium treated oocytes greatly improved the ease and success rate of blastomere subzona insertion, but the value of functionally enucleated oocytes as recipient cells for nuclear transfer requires further investigation.

Characterization of beta-adrenoreceptors on smooth muscle cells from guinea pig stomach

To characterize the beta-adrenergic receptors on guinea pig gastric smooth muscle cells, we examined the effects of beta-adrenergic agonists and antagonists on biological activity, cellular adenosine 3',5'-cyclic monophosphate (cAMP), and radioligand binding. Adrenergic agonists, isoproterenol (ISO), epinephrine (EPI), and norepinephrine (NE), inhibited carbachol-stimulated contraction of muscle cells, with relative potencies (IC50S) of ISO (0.1 microM) greater than EPI (1.4 microM) greater than NE (11 microM). Each agonist increased cellular cAMP, with relative potencies (IC50S) of ISO (0.5 microM) greater than EPI (6.3 microM) greater than NE (56 microM). Binding of the nonselective beta-antagonist 125I-pindolol was temperature-dependent, saturable, reversible, and specific. 125I-pindolol binding was inhibited by the three agonists, with relative potencies (IC50S) of ISO (0.9 microM) greater than EPI (9.6 microM) greater than NE (112 microM). Pindolol inhibited binding of 125I-pindolol with an IC50 of 100 nM. The IC50 for inhibition of binding of 125I-pindolol by the relatively beta 2-selective antagonist ICI 118,551 was 70 nM and for the relatively beta 1-selective antagonist betaxolol was 1,000 nM. Computer analysis of the dose-inhibition curves for binding of 125I-pindolol for the antagonists indicated that gastric smooth muscle cells possess exclusively beta 2-adrenergic receptors of two classes, one class with a high affinity for ICI 118,551 (Kd = 50 nM) and the other with a low affinity for ICI 118,551 (Kd = 30 microM). Our results indicate that beta-adrenergic agonists interact with beta 2-adrenergic receptors on gastric smooth muscle cells to increase cellular cAMP and inhibit muscle contraction.

[Modulation of norepinephrine release in sympathetic nerve endings in renal hypertensive dogs]

Experimental renal hypertensive and normal dogs with femoral arteries constantly perfused were studied. Cocaine was used to block the presynaptic norepinephrine (NE) reuptake and tyramine to initiate the release of NE in sympathetic nerve endings. NE spillover and infusion pressure were measured under basic conditions and during intraarterial infusion of cocaine, tyramine and in combination with alpha 1 and alpha 2 adrenoceptor antagonists. The extent of NE spillover increase induced by infusion of tyramine, the increased infusion pressure by cocaine and tyramine, and the reduced infusion pressure by prazosin were all greater in hypertensive dogs than those in normal dogs, but adrenoceptor antagonist idazoxan further increased tyramine-induced NE spillover in normal dogs only. It was suggested that reduced-regulation of presynaptic alpha 2 adrenoceptors to NE release and increased responsiveness of postsynaptic alpha 1 adrenoceptors to NE were present in hypertensive dogs.

Comparison of Rous sarcoma virus RNA processing in chicken and mouse fibroblasts: evidence for double-spliced RNA in nonpermissive mouse cells

Rous sarcoma virus, an avian retrovirus, transforms but does not replicate in mammalian cells. To determine to what extent differences in RNA splicing might contribute to this lack of productive infection, cloned proviral DNA derived from the Prague A strain of Rous sarcoma virus was transfected into mouse NIH 3T3 cells, and the viral RNA was compared by RNase protection with viral RNA from transfected chicken embryo fibroblasts by using a tandem antisense riboprobe spanning the three major splice sites. The levels of viral RNA in NIH 3T3 cells compared with those in chicken embryo fibroblasts were lower, but the RNA was spliced at increased efficiency. The difference in the ratio of unspliced to spliced RNA levels was not due to the increased lability of unspliced RNA in NIH 3T3 cells. Although chicken embryo fibroblasts contained equal levels of src and env mRNAs, spliced viral mRNAs in NIH 3T3 cells were almost exclusively src. In NIH 3T3 cells the env mRNA was further processed by using a cryptic 5' splice site located within the env coding sequences and the normal src 3' splice site to form a double-spliced mRNA. This mRNA was identical to the src mRNA, except that a 159-nucleotide sequence from the 5' end of the env gene was inserted at the src splice junction. Smaller amounts of single-spliced RNA were also present in which only the region between the cryptic 5' and src 3' splice sites was spliced out. The aberrant processing of the viral env mRNA in NIH 3T3 cells may in part explain the nonpermissiveness of these cells to productive Rous sarcoma virus infection.

Receptor mechanisms for 5-hydroxytryptamine (5-HT) in isolated ovine umbilical vein

5-Hydroxytryptamine (5-HT) and 2,5-dimethoxy-4-methyl-amphetamine (DOM) produced a concentration-dependent contraction in isolated umbilical veins obtained from fetal lambs within 2 weeks of term. Contractions to 5-HT were antagonized by ketanserin, mianserin and methiothepin with the dissociation constants (KB) being 2.17 +/- 0.36, 1.37 +/- 0.55 and 1.98 +/- 0.48 nM, respectively. The order of potency of serotonergic agonists in this tissue was: DOM greater than 5-HT greater than alpha-methyl-5-HT greater than 1(3-chlorophenyl) piperazine (mCPP) greater than m-trifluoromethyl-phenylpiperazine (TFMPP) greater than 8-hydroxy-dipropylaminotetralin (8-OH-DPAT) = 2-methyl-5-HT. alpha-Methyl-5-HT was a full agonist compared to 5-HT. DOM possessed greater affinity but less efficacy than that of 5-HT. The affinities and efficacies of the other agonists studied were lower than those of 5-HT. Variation in the sensitivity and potency of agonists is primarily due to variations in their affinity for 5-HT receptors. Assessment of receptor occupancy vs. functional response demonstrated very little, if any, receptor reserve for 5-HT receptors in this tissue. Contractile responses to DOM, 8-OH-DPAT, mCPP and 2-methyl-5-HT were effectively blocked by ketanserin. The dissociation constants (KB) of ketanserin against these agonists were as follows: DOM, 2.78 +/- 0.85 nM; 8-OH-DPAT, 3.47 +/- 1.12 nM; mCPP, 1.45 +/- 0.51 nM; 2-methyl-5-HT, 1.99 +/- 0.74 nM. The dissociation constant of MDL 72222 (3-tropanyl-3,5-dichlorobenzoate) vs. 5-HT was 13833 nM. No antagonism by prazosin (10(-7) M) or yohimbine (10(-7) M) of the responses to 5-HT was observed. These results indicate that 5-HT2 receptors are present in the ovine umbilical vein. 5-HT3 receptors were not present in this tissue. Activation of alpha-adrenoceptors was not involved in the contractions to 5-HT.

Effects of inositol, 1,4,5-trisphosphate injections into cat spinal motoneurons

Inositol 1,4,5-trisphosphate (IP3) was injected iontophoretically into cat spinal motoneurons in pentobarbital-anaesthetized cats and nonanaesthetized, decerebrate cats. Injections of IP3 induced a long-lasting, reproducible hyperpolarization without consistent change in input resistance. The peak amplitude of post-spike afterhyperpolarization (AHP) was significantly increased by IP3 when the membrane potential was adjusted to the control level. Intracellular injections of Ca2+ chelators, which depressed the Ca2(+)-activated AHP, prevented the IP3-induced long-lasting hyperpolarization, suggesting that IP3 acts by a Ca2(+)-dependent mechanism. Intracellular injections of myo-inositol did not consistently induce hyperpolarizations. Also intracellular injections of Li+, which blocks IP3 catabolism, did not prevent the IP3-evoked hyperpolarization. These data suggest that IP3 itself, rather than its breakdown product myo-inositol, is mainly responsible for the hyperpolarizing effect. Possible mechanisms for the IP3-induced hyperpolarization are discussed.

Plant regeneration from cotyledon protoplasts of Xinjiang muskmelon

Cotyledon protoplasts were isolated from seedlings of Xinjiang muskelon (Cucumis melo var.saccharinus) grown under sterile conditions and cultured in modified Miller medium. High frequency division of the protoplast-derived cells was observed. Agarose bead culture with B6S3 tobacco crown gall nurse cells was found most suitable for the cotyledon protoplasts when compared with other culture methods. Intact plants were regenerated from the protocalli by a two-step culture procedure with liquid and then solid media.

Virtual clock: a new traffic control algorithm for packet switching networks

A challenging research issue in high speed networking is how to control the transmission rate of statistical data flows. This paper describes a new algorithm, VirtualClock, for data traffic control in high-speed networks. VirtualClock maintains the statistical multiplexing flexibility of pocket switching while ensuring each data flow its reserved average throughput rate at the same time. The algorithm has been tested through simulation.

Heterogeneity in direct cytotoxic function of L3T4 T cells. TH1 clones express higher cytotoxic activity to antigen-presenting cells than TH2 clones

In the process of generating culture supernatant from T cell clones, with anti-CD3 antibodies and the B lymphoma A20 as APC, a striking difference in the stimulation of TH1 and TH2 clones was observed, i.e., TH2 clones produced higher levels of lymphokines than TH1 clones. This prompted us to test the hypothesis that differential killing of APC (thus the removal of stimuli) by T cells led to differential T cell activation. By studying a panel of five TH1 and seven TH2 clones, it was demonstrated that TH1 clones mediated significantly higher levels of cytotoxicity toward A20 cells in the presence of soluble anti-CD3 antibody (as opposed to immobilized anti-CD3). Although T cell clones could, when activated with immobilized anti-CD3, produce lymphokines cytotoxic to A20 cells, experiments in which lymphokine production was blocked indicated that T cell clones, in the presence of soluble anti-CD3, mediated killing of A20 through direct cytotoxicity. A higher level of cytotoxicity, by TH1 compared with TH2 clones, was not restricted to anti-CD3 or a particular target cell type, because it also occurred with Con A- or Ag-dependent killing (a monocyte-macrophage cell line), and LPS blasts. Furthermore, the higher cytotoxic activity of TH1 clones compared with TH2 clones was independent of the stage of T cell activation and was unlikely a result of the length of in vitro culture. High levels of killing of APC led to low levels of T cell activation, the significance of which may be as a negative feedback mechanism in the immune response. Other biologic relevancies of higher cytotoxic activity in TH1 vs TH2 cells were also discussed.

Heterogeneity in direct cytotoxic function of L3T4 T cells. TH1 clones express higher cytotoxic activity to antigen-presenting cells than TH2 clones

In the process of generating culture supernatant from T cell clones, with anti-CD3 antibodies and the B lymphoma A20 as APC, a striking difference in the stimulation of TH1 and TH2 clones was observed, i.e., TH2 clones produced higher levels of lymphokines than TH1 clones. This prompted us to test the hypothesis that differential killing of APC (thus the removal of stimuli) by T cells led to differential T cell activation. By studying a panel of five TH1 and seven TH2 clones, it was demonstrated that TH1 clones mediated significantly higher levels of cytotoxicity toward A20 cells in the presence of soluble anti-CD3 antibody (as opposed to immobilized anti-CD3). Although T cell clones could, when activated with immobilized anti-CD3, produce lymphokines cytotoxic to A20 cells, experiments in which lymphokine production was blocked indicated that T cell clones, in the presence of soluble anti-CD3, mediated killing of A20 through direct cytotoxicity. A higher level of cytotoxicity, by TH1 compared with TH2 clones, was not restricted to anti-CD3 or a particular target cell type, because it also occurred with Con A- or Ag-dependent killing (a monocyte-macrophage cell line), and LPS blasts. Furthermore, the higher cytotoxic activity of TH1 clones compared with TH2 clones was independent of the stage of T cell activation and was unlikely a result of the length of in vitro culture. High levels of killing of APC led to low levels of T cell activation, the significance of which may be as a negative feedback mechanism in the immune response. Other biologic relevancies of higher cytotoxic activity in TH1 vs TH2 cells were also discussed.

Analysis of HLA-DQB and HLA-DPB alleles in Graves' disease by oligonucleotide probing of enzymatically amplified DNA

We have tested the possible association of HLA-DQB and HLA-DPB alleles with Graves' thyrotoxicosis, with or without severe ophthalmopathy, by polymerase chain amplification of genomic DNA and allele-specific oligonucleotide probing. There was no significantly abnormal distribution of DQB alleles compared to 50 control subjects except for a reduced prevalence of DQw 3.1 in the Graves' patients with severe ophthalmopathy (X2 = 6.23, P less than 0.02). HLA-DPB 2.1/8 was found in only 1 of 40 of these patients compared with 15 of the controls (X2 = 11.49, P less than 0.001). Ten of 48 patients with Graves' disease but without clinically significant eye involvement were HLA-DPB 2.1/8 positive, not significantly different from controls, but significantly different from the ophthalmopathy group (X2 = 6.70, P less than 0.01). The other DPB alleles in both groups of Graves' disease patients were the same as controls. These results suggest that HLA-DPB 2.1/8 may confer a protective effect in Graves' disease with respect to ophthalmopathy.

Human suppressor T cell clones lack CD28

Previously we showed that certain T cell lines and clones from a lepromatous leprosy patient displayed a dose-dependent suppression of the proliferation of autologous T cells to Mycobacterium leprae (M. leprae) but not mitogen or an unrelated antigen. The latter cells were also cloned and did not display this suppressive activity, were CD4+ and proliferated vigorously to M. leprae presented by autologous HLA-DR molecules. We shall refer to these cells as T helper (Th) cells. Most of the suppressive T cell clones (Ts) were also CD4+ and also proliferated to M. leprae presented by HLA-DR, but much less strongly than Th cells. In this study we report on our search for (a) the mechanism of this apparently antigen-specific suppression by T cells, and (b) a possible phenotypic difference between Th and Ts clones. The two main conclusions are that Ts clones possess a lytic machinery, but that M. leprae-specific suppression and cytotoxicity can be clearly dissociated, and that the only phenotypic difference between Th and Ts is the presence of the CD28 marker on Th and its absence on Ts clones.

Characterization of 5-hydroxytryptamine receptors on isolated ovine uterine artery in late pregnancy

5-Hydroxytryptamine (5-HT) and 2,5-dimethoxy-4-methyl-amphetamine (DOM) are potent agonists on isolated ovine uterine arteries in late pregnancy. Similar pA2 values (8.56 and 8.33, respectively) of ketanserin, tested against 5-HT and DOM, indicate that responses produced by both agonists are mediated by the 5-HT2 receptor. The contractions produced by 8-OH-DPAT and 2-methyl-5-HT were also blocked by ketanserin (10(-8) M) with the dissociation constants (KB) being 2.49 and 2.88 nM, respectively. This provides evidence that these agonists are activating 5-HT2 receptors in the ovine uterine artery. DOM was more potent than 5-HT, but had a similar efficacy to that of 5-HT. The greater affinity of DOM may explain its greater potency. The dissociation constants (KA) of 5-HT and DOM acting on 5-HT receptors were determined by analysis of concentration-response data before and after fractional inactivation of receptors with dibenamine. The mean KA values for 5-HT and DOM were 3.7 +/- 0.7 x 10(-7) and 1.8 +/- 0.3 x 10(-7) M, respectively. Assessment of receptor occupancy vs. functional response demonstrated little or no receptor reserve in this tissue. Several other 5-HT receptor agonists caused contractions but were much less potent than 5-HT. The order of potency of these agonists was determined to be DOM greater than 5-HT greater than or equal to alpha-methyl-5-HT much greater than 8-hydroxy-dipropylaminotetralin (8-OH-DPAT) greater than 2-methyl-5-HT greater than 1-(3-chlorophenyl) piperazine (mCPP) greater than m-trifluoromethyl-phenylpiperazine (TFMPP).(ABSTRACT TRUNCATED AT 250 WORDS)

[Effect of high carbohydrate and high fat diets on plasma glucose, insulin and lipids in normal and hypertriglyceridemic subjects]

The fasting plasma glucose, insulin and lipids response to high-carbohydrate-low-fat diets and low-carbohydrate-high-fat diets in normal subjects and patients with endogenous hypertriglyceridemia was observed. The normal, high carbohydrate and high fat diets consisted of 60%, 80% and 40% carbohydrate, 25%, 5% and 45% fat and 15% protein of total calorie respectively. The fasting plasma glucose levels increased (P less than 0.01) on day 1, insulin increased on day 3 (P less than 0.01 and P less than 0.05) and TG levels increased on days 3 and 5 after taking high carbohydrate diets both in the normal and hypertriglyceridemic groups. The fasting plasma TC and HDL-C decreased on high carbohydrate diets mainly in the hypertriglyceridemic group. The fasting plasma glucose slightly decreased on day 5, TG decreased on day 1 (P less than 0.05) and TC increased on day 1 and 3 (P less than 0.01) after taking high fat diets, but no differences were observed in insulin levels. Fasting plasma HDL-C levels in the normal group remained unchanged, but significantly decreased 3 days after taking high fat diets in the hypertriglyceridemic group (P less than 0.001). Our results indicate that high carbohydrate intake may be an important cause of hypertriglyceridemia in our country. This diet may cause a slight increase in the blood glucose level, which in turn stimulates an increase in plasma lipids and decrease in HDL-C, which is associated with an increase in the incident of coronary heart disease.(ABSTRACT TRUNCATED AT 250 WORDS)