Epitope-specific glutamic acid decarboxylase-65 autoantibodies in intravenous immunoglobulin preparations

Intravenous immunoglobulin (IVIG) has been used to treat many autoimmune disorders including Stiff-Man Syndrome (SMS). SMS is a neurological disorder associated with an immune-mediated deficiency of gamma-aminobutyric acid (GABA) due to autoantibodies against the GABA synthesizing enzyme glutamic acid decarboxylase-65 (GAD65). GAD65 autoantibodies are present among 1-2% of healthy individuals. It can therefore not be excluded that GAD65 autoantibodies may be present in IVIG, which is prepared from multiple blood donors. We report here that GAD65 but not IA-2 autoantibodies were present in commercial IVIG preparations. The presence of autoantibodies may affect the outcome of IVIG treatment and screening commercial preparations of IVIG for GAD65 autoantibodies is therefore recommended before treating patients.

Mortality risks of peritoneal dialysis and hemodialysis

Studies of outcomes associated with dialysis therapies have yielded conflicting results. Bloembergen et al showed that prevalent patients on continuous ambulatory peritoneal dialysis (CAPD) or continuous cycling peritoneal dialysis (CCPD) had a 19% higher mortality risk than hemodialysis patients, and Fenton et al, analyzing Canadian incident patients, found a 27% lower risk. Attempting to reconcile these differences, we evaluated incident Medicare patients (99,048 on hemodialysis, 18,110 on CAPD/CCPD) from 1994 through 1996, following up to June 30, 1997. Patients were followed to transplantation, death, loss to follow-up, 60 days after modality change, or end of the study period. For each 3-month survival period, we used an interval Poisson regression to compare death rates, adjusting for age, gender, race, and primary renal diagnosis. A Cox regression was used to evaluate cause-specific mortality, and proportionality was addressed in both regressions by separating diabetic and nondiabetic patients. The Poisson regressions showed CAPD/CCPD to have outcomes comparable with or significantly better than hemodialysis, although results varied over time. The Cox regression found a lower mortality risk in nondiabetic CAPD/CCPD patients (women younger than 55 years: risk ratio [RR] = 0. 61; Cl, 0.59 to 0.66; women age 55 years or older: RR = 0.87; Cl, 0. 84 to 0.91; men younger than 55 years: RR = 0.72; Cl, 0.67 to 0.77; men age 55 years or older: RR = 0.87; Cl, 0.83 to 0.92) and in diabetic CAPD/CCPD patients younger than 55 (women: RR = 0.88; Cl, 0. 82 to 0.94; men: RR = 0.86; Cl, 0.81 to 0.92). The risk of all-cause death for female diabetics 55 years of age and older, in contrast, was 1.21 (Cl, 1.17 to 1.24) for CAPD/CCPD, and in cause-specific analyses, these patients had a significantly higher risk of infectious death. We conclude that, overall, within the first 2 years of therapy, short-term CAPD/CCPD appears to be associated with superior outcomes compared with hemodialysis. It also appears that patients on the two therapies have different mortality patterns over time, a nonproportionality that makes survival analyses vulnerable to the length of follow-up. Further investigation is needed to evaluate both the potential explanations for these findings and the use of more advanced statistical methods in the analysis of mortality rates associated with these dialytic therapies.

AP180 and AP-2 interact directly in a complex that cooperatively assembles clathrin

Clathrin-coated vesicles are involved in protein and lipid trafficking between intracellular compartments in eukaryotic cells. AP-2 and AP180 are the resident coat proteins of clathrin-coated vesicles in nerve terminals, and interactions between these proteins could be important in vesicle dynamics. AP180 and AP-2 each assemble clathrin efficiently under acidic conditions, but neither protein will assemble clathrin efficiently at physiological pH. We find that there is a direct, clathrin-independent interaction between AP180 and AP-2 and that the AP180-AP-2 complex is more efficient at assembling clathrin under physiological conditions than is either protein alone. AP180 is phosphorylated in vivo, and in crude vesicle extracts its phosphorylation is enhanced by stimulation of casein kinase II, which is known to be present in coated vesicles. We find that recombinant AP180 is a substrate for casein kinase II in vitro and that its phosphorylation weakens both the binding of AP-2 by AP180 and the cooperative clathrin assembly activity of these proteins. We have localized the binding site for AP-2 to amino acids 623-680 of AP180. The AP180/AP-2 interaction can be disrupted by a recombinant AP180 fragment containing the AP-2 binding site, and this fragment also disrupts the cooperative clathrin assembly activity of the AP180-AP-2 complex. These results indicate that AP180 and AP-2 interact directly to form a complex that assembles clathrin more efficiently than either protein alone. Phosphorylation of AP180, by modulating the affinity of AP180 for AP-2, may contribute to the regulation of clathrin assembly in vivo.

Nitric oxide mediates IL-1beta stimulation of heat shock protein but not IL-1beta inhibition of glutamic acid decarboxylase

Interleukin-1beta (IL-1beta) has been implicated to play an important role in the autoimmune beta cell lesion of insulin-dependent diabetes mellitus (IDDM) because of its inhibition of insulin secretion, direct islet cytotoxicity and alteration of islet cell antigen expression. We have previously demonstrated that IL-1beta inhibits glutamic acid decarboxylase-65 (GAD-65) and increases heat shock protein-70 (HSP-70) expression in islet cells. IL-1beta stimulates the inducible form of nitric oxide (NO) synthase and the resultant increased NO mediates many of IL-1beta's effects. In this study we investigated the role of the NO pathway in mediating the effects of IL-1beta on GAD-65 and HSP-70 expression and on insulin secretion. Islets isolated from Sprague-Dawley rats were cultured with IL-1beta and aminoguanidine (AG), an inhibitor of inducible NO synthase, individually and in combination for 24 h. Accumulated nitrite production, insulin release and islet expression of GAD-65 and HSP-70 were measured. We found that (1) IL-1beta at 10 U/ml increased nitrite production, inhibited insulin release, increased HSP-70 expression and decreased GAD-65 expression. (2) AG alone at 1 mM/ml had no effect on nitrite production, insulin release, GAD-65 and HSP-70 expression. (3) In combination, AG completely blocked IL-1beta increased nitrite production, reversed IL-1beta inhibited insulin release by approximately 50%, completely reversed IL-1beta increased HSP-70 expression, but did not reverse IL-1beta inhibited GAD-65 expression. Our findings indicate that the effect of IL-1beta on HSP-70 expression is mediated by NO production, whereas a NO-independent pathway is involved in the effect of IL-1beta on GAD-65 expression and insulin secretion.

The endogenous chromophore of retinal G protein-coupled receptor opsin from the pigment epithelium

The recent identification of nonvisual opsins has revealed an expanding family of vertebrate opsin genes. The retinal pigment epithelium (RPE) and Müller cells contain a blue and UV light-absorbing opsin, the RPE retinal G protein-coupled receptor (RGR, or RGR opsin). The spectral properties of RGR purified from bovine RPE suggest that RGR is conjugated in vivo to a retinal chromophore through a covalent Schiff base bond. In this study, the isomeric structure of the endogenous chromophore of RGR was identified by the hydroxylamine derivatization method. The retinaloximes derived from RGR in the dark consisted predominantly of the all-trans isomer. Irradiation of RGR with 470-nm monochromatic or near-UV light resulted in stereospecific isomerization of the bound all-trans-retinal to an 11-cis configuration. The stereospecificity of photoisomerization of the all-trans-retinal chromophore of RGR was lost by denaturation of the protein in SDS. Under the in vitro conditions, the photosensitivity of RGR is at least 34% that of bovine rhodopsin. These results provide evidence that RGR is bound in vivo primarily to all-trans-retinal and is capable of operating as a stereospecific photoisomerase that generates 11-cis-retinal in the pigment epithelium.

Sunlight mutagenesis: changes in mutational specificity during the irradiation of phage M13mp2

We reported previously that the mutations in phage M13mp2, a single-stranded DNA phage, induced by sunlight exposure are predominated by G-to-C transversions. We have now made an unexpected observation that an exposure to sunlight for a short period of time results in induction mainly of C-to-T transitions while a longer exposure results in the induction of G-to-C transversions. This peculiar phenomenon suggests that DNA damage formed by initial sunlight exposure can be transformed during an elongated exposure. 7, 8-Dihydro-8-oxoguanine (8-oxoG) in DNA might be involved in the shift of the mutational specificity, as 8-oxoG was formed in the phage DNA upon the sunlight exposure. We also compared the mutagenic activity of UVB irradiation with that of sunlight exposure. The results demonstrate that the genotoxic properties of sunlight and UVB in phage M13mp2 mutagenesis are different. The shift in the mutational specificity associated with the dose of the sunlight may call for general cautions in the studies of agent-induced mutagenesis.

Radioimmunoassay for glutamic acid decarboxylase-65

BACKGROUND

Glutamic acid decarboxylase-65 (GAD65), the enzyme that catalyzes the formation of gamma-aminobutyric acid (GABA), is the major autoantigen in both type 1 (insulin-dependent) diabetes and stiff-man syndrome (SMS). The observation that GAD65 autoantibodies may be present for years before the clinical onset of diabetes raises the question of when GAD65 is available to initiate an immune response to allow the formation of autoantibodies. In order to address this question it will be necessary to measure GAD65 in tissue, cells, and plasma.

METHODS

A radioimmunoassay (RIA) was developed for GAD65 based on the use of a polyclonal rabbit antiserum directed to the N-terminus of GAD65.

RESULTS

Using the GAD65 RIA, we have determined the GAD65 content in a human GAD65 gene transfected cell line and in beta-cell preparations from different species. The assay detects an increase of immunoreactive GAD65 after glucose-stimulation and GAD65 that is discharged from rat beta cells after their exposure to the diabetogenic agent streptozotocin. It also measures good recovery of GAD65 added to human plasma samples.

CONCLUSIONS

The GAD65 RIA makes it possible to determine both cellular and extracellular levels of GAD65; this might be useful in investigating the mechanisms leading to the formation of GAD65 autoantibodies in type 1 diabetes and SMS patients.

Structure and developmental expression of the mouse RGR opsin gene

PURPOSE

The aim of this study is to isolate and characterize cDNA clones and the genes that encode mouse RPE retinal G protein-coupled receptor (RGR) and to analyze expression of the RGR gene in the developing mouse retina. The conserved amino acid sequences of RGR from various mammals can be compared to the amino acid sequence motif of G protein-coupled receptors.

METHODS

Mouse RGR cDNA and gene clones were isolated from a retina cDNA library and 129SV genomic DNA library, respectively. The expression of RGR in the developing C57BL/6J mouse retina was analyzed by immunohistochemical staining with a polyclonal antipeptide antibody.

RESULTS

The deduced amino acid sequence of mouse RGR is 78% and 81% identical to that of bovine and human RGR, respectively. The mouse RGR gene is split into seven exons and extends about 11 kb. Two predominant mRNA transcripts, 1.9 and 1.7 kb in length, and a third, relatively faint, 5.5-kb transcript were detected in mouse eye by hybridization to a RGR cDNA probe. Frozen sections of C57BL/6J mouse retina at various stages of development were incubated with a mouse RGR antipeptide antibody. RGR immunoreactivity was first seen at postnatal day 2 (P2) in centrally located RPE cells. From day P6 to P12, there was an increase in the number and intensity of immunoreactive RPE cells in the central and mid-peripheral regions of the retina, while the most peripheral RPE cells were still negative. By day P16, the length of the RPE monolayer was immunoreactive, and staining of the central RPE cells was markedly more intense than at younger ages.

CONCLUSIONS

Mouse and human RGR are highly conserved. A gradient of RGR expression in RPE extends from the central to the peripheral retina during development. In reference to the appearance of melanin-positive differentiated RPE cells, the induction of RGR expression is a relatively late event in the maturation of the retina.

Psychoactive substance use in three sites in China: gender differences and related factors

One year prevalence rates for psychoactive substance use are reported based on community surveys performed in three sites in China: Hunan, Heilongjiang and Jiangsu. The data were gathered on more than 14,000 respondents (15-65 years old). The drinking rates were from 58.3 to 82.6% for men and from 16.3 to 31.4% for women. Smoking rates range from 64.9 to 68.1% for men and from 0.1 to 20.5% for women. Most drinkers were light users and most smokers were heavy users. Illicit drug use was observed at Hunan. Regarding frequency and quantity of psychoactive substance use, women are lighter consumers than their male counterparts except for use of minor tranquilizers and analgesics. The psychosocial factors related to drinking and smoking were also investigated in this study.

Detection of Chlamydia trachomatis antibodies by 2 novel tests: rELISA and peptide EIA

The performance of 2 newly developed enzyme immunoassays (EIAs) intended for the routine serological diagnosis of chlamydial infections was evaluated. rELISA is based on a recombinant lipopolysaccharide antigen which detects chlamydia genus-specific antibodies, and Chlamydia trachomatis EIA is based on a peptide derived from major outer membrane protein and is therefore species-specific. Both tests distinguished patients with tubal factor infertility (TFI) or pelvic inflammatory disease (PID) from the controls. The prevalence of IgA antibodies was higher for the PID patients than for the TFI patients; the finding indicates a more active state of infections for the PID patients. Furthermore, C. trachomatis EIA detected more IgG antibodies in the TFI patients than in patients with non-tubal factor infertility. In conclusion, rELISA detected chlamydial antibodies in general, and C. trachomatis EIA detected species-specific antibodies. These EIA tests may be useful in the serodiagnosis of chlamydial infection.

[Regulatory role of 5-hydroxytryptamine and motilin in migrating motor complex of small bowel in dogs]

Migrating motor complex (MMC) was recorded by chronically implanted strain gauge transducers on the serosa of small bowel in conscious dogs. Two silastic catheters for injecting drugs and taking blood samples were put respectively in a vena jugularis externa and in a jejunal artery which perfused a 10-15 cm intestinal segment. The present study was undertaken to observe the effect of drugs administered intravenously and intraarterially on MMC and alterations of plasma 5-hydroxytryptamine (5-HT) and motilin in different phases of MMC. The results showed: (1) Levels of plasma 5-HT and motilin showed cyclical fluctuations in different phases of MMC, and 5-HT reached peak before peak of motilin. Plasma 5-HT level reached a peak [(41.2 +/- 1.3) ng/ml] in the later period of phase II, which increased significantly as compared with phase I [(22.4 +/- 1.1) ng/ml] (P < 0.01), but plasma motilin level had a peak [(580.0 +/- 30.2) pg/ml] in phase III of MMC, which was higher than that in phase I [(140.0 +/- 21.0) pg/ml] (P < 0.01). (2) Intravenous motilin and intraarterial 5-HT and motilin could induce phase III contraction in the canine proximal small bowel and in the perfused segment respectively. Amplitude of contractions caused by motilin was higher than that by 5-HT in the perfused segment. (3) 5-HT receptor antagonist, motilin antiserum, 5,6-dihydroxytryptamine and tetrodotoxin perfused intra-arterially inhibited expression of MMC in the perfused segment and its caudal propagation. We conclude that plasma 5-HT and motilin may be dominant factors which initiate MMC of canine small bowel, and 5-HT peak appears before peak of motilin. 5-HT neurons and motilin neurons in enteric nervous system may play an important role in controlling MMC of canine small bowel.

[Antagonistic action of organic selenium on lead poisoning]

Ninety white rats were treated with liquid lead acetate. When the concentration of lead in urine was more than (0.81 +/- 0.26) mg/L and blood lead was more than (4.8 +/- 0.33) mg/L, the rats were divided into three groups randomly. The oxygenic damage indicators in serum showed SOD activity decreased and MDA content increased. In one group of lead rats fed with an organic selenium compound (code FCQY) the SOD activities were high and the lipid peroxidation was inhibited compared with controls without selenium supplementation. The lead contents of bone, kidney and liver were measured. The results suggested that the organic selenium compound could interfere with the absorption and accumulation of lead.

[Detection of rotavirus RNA using DIG labelled probe prepared by polymerase chain reaction]

The digoxigenin (DIG) labelled cDNA probe of rotavirus was directly prepared by polymerase chain reaction (PCR). The results of cDNA-RNA hybridization showed that the DIG-cDNA probe exhibits rotavirus specificity and can detect as tiny as 10 pg rotavirus RNA. 120 fecal samples of diarrhea from infants and young children were tested by dot-blot hybridization. It was shown that the positive rate of dot-blot hybridization(65.0%) was significantly higher than that of PAGE(49.1%). This study indicated that direct preparation of DIG-labelled rotavirus-cDNA probe by PCR is much faster and simpler than common method of labeling.

[Effects of heat, noise, and their combination on plasma atrial natriuretic peptides, cardiodilatin, endogenous digitalis like substance, angiotensin II and endothelin in rats]

Plasma contents of atrial natriuretic peptides (ANP), cardiodilatin (CDD), endogenous digitalis like substance (EDLS), angiotensin II (A II) and endothelin (ET) were determined in rats following exposure to high temperature, noise and a combination of the two. It was found that plasma content of ANP after heat exposure decreased significantly, CDD and A II content after heat or noise exposure increased obviously, ET content decreased significantly after exposure to combined factors. ANP and CDD have the same physiological function and changes. ANP, CDD and A II observed in the present study were considered to be compensatory responses. It is harmful if exposure to high temperature or noise lasts for a long time.

[Comparison of immunity improving effects of different processed cortex Eucommiae]

The immunity improving effects of different processed Cortex Eucomiae was compared. The results show that the effect of post-processed drugs is obviously stronger than that of pre-processed ones. No obvious difference have been found in the action of the post-processed drugs.

Immunosuppression by metastatic lymphoma derived altered retroviral gp70 molecule

In this report we describe the characteristics of an immunosuppressive molecule from an Abelson Leukemia Virus transformed highly malignant and metastatic RAW117-H10 murine large cell lymphoma cells. Our studies have shown that the mitomycin-c treated or irradiated RAW117-H10 cells very significantly (p < 0.001) inhibited the nitrogen induced proliferation of normal Balb/c splenocytes. The cell surface extracts from the immunosuppressive RAW117-H10 lymphoma cells significantly inhibited the in vitro T cell or NK/LAK cell functions. Our in vivo studies demonstrated that there was a significant suppression of immune response in the Balb/c mice bearing RAW117-H10 cells when compared with mice bearing low metastatic parental RAW117-P cells or control mice. Subsequently we isolated and purified the main molecule responsible for this immunosuppression and found that the molecule is a glycoprotein with a molecular weight of 70 kD with an isoelectric point of 4.3, which cross reacted with antibodies to murine leukemia virus envelope gp70 molecules. Further analysis using immunoelectrophoresis, molecular probing techniques, and mannose specific lectin binding assay revealed that the immunosuppressive 70 kD molecule, is different from the wild type MLV envelope gp70 molecule and thus appears to be an altered gp70 molecule. These studies demonstrate that the metastatic lymphoma associated immunosuppression may facilitate the growth and metastasis of tumor cells. Our results also elucidate the possible mechanism(s) of retrovirus induced immunosuppression and the molecular basis of this retroviral envelope-mediated process in viral pathogenesis and tumor progression.

[Analysis of vectorcardiogram (VCG) in 150 healthy pilots]

150 healthy male pilots, aged 22-46 years (31 +/- 5) were examined with the HBD-II A instrument. The results showed that vectorcardiogram (VCG) parameters of pilots were within the normal value by clinical diagnosis standard of VCG, but some indexes of VCG appeared different from the normal people, these might be the characteristics of VCG of pilots. The present study provided some new parameters of VCG such as P loop. The results of this study may be used for pilots selection and real-time medical monitoring for pilots on ground training.

Regulation of AP-3 function by inositides. Identification of phosphatidylinositol 3,4,5-trisphosphate as a potent ligand

As part of the growing effort to understand the role inositol phosphates and inositol lipids play in the regulation of vesicle traffic within nerve terminals, we determined whether or not the synapse-specific clathrin assembly protein AP-3 can interact with inositol lipids. We found that soluble dioctanoyl-phosphatidylinositol 3,4,5-trisphosphate (DiC8PtdIns(3,4, 5)P3) was only 7.5-fold weaker a ligand than D-myo-inositol hexakisphosphate in assays that measured the displacement of D-myo-[3H]inositol hexakisphosphate. In functional assays we found that both of these ligands inhibited clathrin assembly, but DiC8-PtdIns(3,4,5)P3 was more potent and exhibited a larger maximal effect. We also examined the structural features of DiC8-PtdIns(3,4, 5)P3 that establish specificity. Dioctanoyl-phosphatidylinositol 3, 4-bisphosphate, which does not have a 5-phosphate, and 4, 5-O-bisphosphoryl-D-myo-inosityl 1-O-(1, 2-O-diundecyl)-sn-3-glycerylphosphate, which does not have a 3-phosphate, were, respectively, 2-fold and 4-fold less potent than DiC8-PtdIns(3,4,5)P3 as inhibitors of clathrin assembly. Deacylation of DiC8-PtdIns(3,4,5)P3 reduced its affinity for AP-3 almost 20-fold, and also dramatically lowered its ability to inhibit clathrin assembly. The deacylated products of the soluble derivatives of phosphatidylinositol 3,4-bisphosphate and phosphatidylinositol 4, 5-bisphosphate were both not significant inhibitors of clathrin assembly. It therefore appears that the interactions of inositides with AP-3 should not be considered simply in terms of electrostatic effects of the highly charged phosphate groups. Ligand specificity appears also to be mediated by hydrophobic interactions with the fatty-acyl chains of the inositol lipids.

[Effect of heat, noise and their combination on plasma and myocardial angiotensin II in rats]

Effects of heat (40 degrees C, relative humidity 82%), noise (115dB) and the combination of heat and noise on angiotensin (A II) content in plasma and myocardia was observed in rats. The results showed: (1) plasma A II in control group, heat group, noise group and combined group were 358.72 +/- 35.78, 624.08 +/- 36.32, 783.27 +/- 34.32 and 619.65 +/- 37.72 pg/ml respectively. The A II content in heat group, noise group and combined group are significantly higher than that of the control group (P<0.01). The increase in noise group was significant as compared with those in the heat group and combined group (P<0.05). (2) The myocardia A II in control group, heat group, noise group and combined group were 594.78 +/- 82.46, 935.10 +/- 15l.51, 326.22 +/- 28.45, and 438.37 +/- 58.63 pg/mg W.W respectively. The myocardial A II content in heat group was significantly higher (P<0.01), but that in noise group than the control was significantly lower(P<0.O5).

[Evaluation study on determination of ZPP in blood with hematofluorometer]

The authors studied the normalization and evaluation of the method detecting the zinc protoporphyrin (ZPP) by direct displaying blood fluorescent. The results revealed that this method was highly accurate and precise. The relative humidity not more than 90% had no influence to the results. The detection limit of this method was 0.1 microg/g. The linear range of standard curve was 0-15 microg/g, and the precision in batch RSD=0.27%-1.93%. On the accuracy side, the three concentration curving values of ZPP standard material in blood were all within the range of indefinition of given values. If the samples were not detected rapidly and the blood was diluted by heparin, it might be preserved at 4 degrees C for 3 days, at -8 degrees C for 8 days. The blank fluorescent value of glassy cover made in China is less than 3.5 microg/g, Hb can substitute KLI glassy cover. This method can analyse one sample per minute, has advantage of rapidity, convenience, accuracy and reliablity.

Cloning and characterization of cDNA for adenosine kinase from mammalian (Chinese hamster, mouse, human and rat) species. High frequency mutants of Chinese hamster ovary cells involve structural alterations in the gene

The enzyme adenosine kinase constitutes the major purine nucleoside phosphorylating activity in mammalian cells. In view of its central role in adenosine metabolism, which is an important physiological regulator, an understanding of the primary structure of adenosine kinase is of much interest. Using microsequence information from peptides derived from purified Syrian hamster liver enzyme, we have succeeded in isolating full length cDNA clones encoding adenosine kinase from Chinese hamster ovary cells and mouse 3T3 cells. The open reading frames in these clones consist of 334 and 335 amino acids and encode proteins of molecular masses 37364 Da and 37489 Da, respectively. In addition, the coding and upstream sequences for adenosine kinase from human (HeLa cells) and rat liver have also been cloned and sequenced. Transfection of an adenosine-kinase-deficient mutant (selected for resistance to the adenosine analog toyocamycin) of Chinese hamster ovary cells with a plasmid containing the cloned adenosine kinase cDNA, leads to regaining of adenosine kinase activity in the transformed cell. The adenosine kinase transformants also simultaneously lost their toyocamycin resistance and became similarly sensitive to the analog as the parental wild-type Chinese hamster ovary cells. The cloned adenosine kinase cDNA was also used to examine structural changes in mutants affected in adenosine kinase. In Chinese hamster ovary cells, one type of mutant that lacks adenosine kinase activity and displays high degree of resistance to various adenosine analogs, is obtained at an unusually high spontaneous frequency (10(-4)-10(-3)). Results of Southern and northern-blot analysis provide evidence that this group of mutants involves gross structural alterations affecting the adenosine kinase gene. Such structural alterations are not observed in another type of mutant which exhibits increased resistance only to C-adenosine analogs. Sequence similarity searches indicate that several of the bacterial and yeast sugar kinases (ribokinase, fructokinase and inosine-guanosine kinase) exhibit limited but significant similarity to the mammalian adenosine kinase. The sequence similarity data support the possibility that adenosine kinase shares a common evolutionary ancestor with these protein sequences.

Major histocompatibility complex class I molecule expression is normal on peripheral blood lymphocytes from patients with insulin-dependent diabetes mellitus

Recent work from one laboratory has shown, in both nonobese diabetic mice and humans, an association between insulin-dependent diabetes mellitus (IDDM) and quantitative difference in MHC class I molecule expression. This reported decrease in MHC class I molecule expression is very controversial in the nonobese diabetic mouse model of IDDM, but to our knowledge, it has not been evaluated by another group in human IDDM. To evaluate this question, we studied 30 patients with IDDM and 30 age- and sex-matched normal controls. MHC class I molecule expression was measured by flow cytometry with conformational-dependent MHC class I mAbs. The mean antigen density of MHC class I molecule expression in IDDM vs. normal control is 454+/-34 vs. 440+/-28 for lymphocytes and 1,440+/-117 vs. 1,494+/- 117 for monocytes, both P > 0.05. Three conformational-dependent MHC class I antibodies showed consistent results. To estimate the biological variation of MHC class I molecule expression in normal controls, we also studied 10 age- and sex-matched normal control pairs. Using X +/-SD of the percentage difference of mean antigen density in the normal control pairs as our definition of normal, we found that 70% (21/30) of IDDM patients had normal, 13% (4/30) of IDDM patients had decreased, and 17% (5/30) of IDDM patients had increased MHC class I molecule expression on lymphocytes. All IDDM patients showed normal MHC class I expression on monocytes. In conclusion, we find that there is no consistent decrease in MHC class I molecule expression on either lymphocytes or monocytes from patients with IDDM. The MHC class I molecule expression observed in IDDM patients is largely within the expected biological variation of MHC class I molecule expression that has been observed in normal controls.

[Effect of processing of the contents of pinoresinol diglucoside in cortex Eucommiae]

The contents of pinoresinol diglucoside in different processed products of Cortex Eucommiae were determined by HPLC. The result has shown that the contents of pinoresinol diglucoside in post-processed drugs are higher than those in pre-processed ones.

Blue and ultraviolet light-absorbing opsin from the retinal pigment epithelium

The retinal pigment epithelium (RPE) contains an abundant opsin that is distinct from rhodopsin and cone visual pigments and is able to bind the retinaldehyde chromophore. The putative retinal G protein-coupled receptor (RGR) was isolated in digitonin solution from bovine RPE microsomes and copurified consistently with a minor 34-kDa protein. The absorption spectrum of RGR revealed endogenous pH-sensitive absorbance in the blue and near-ultraviolet regions of light. Membrane-bound RGR was incubated with exogenously added all-trans-retinal and formed two long-lived pH-dependent photopigments with absorption maxima of 469 +/- 2.4 and 370 +/- 7.3 nm. The effects of hydrogen ion concentration suggest that the blue and near-UV photopigments are tautomeric forms of RGR, in which an all-trans-retinal Schiff base is protonated or unprotonated, respectively. The RPE pigment was also demonstrable by its reactivity to hydroxylamine in the dark. The retinaldehyde-RGR conjugate at neutral pH favors the near-UV pigment and is a novel light-absorbing opsin in the vertebrate eye.

Pentavalent ions dependency of mammalian adenosine kinase

The enzyme adenosine kinase (AK) has been purified to homogeneity from Syrian hamster and bovine livers. The purified enzymes from both these sources have a Mr of approximately 38 kDa, as determined by gel-filtration and SDS-polyacrylamide gel electrophoresis. A novel characteristic of AK observed here is that its catalytic activity shows a nearly complete dependence upon the presence of pentavalent ions such as phosphate (P(i)), arsenate or vanadate. Maximal AK activity was observed in the presence of either 2-3 mM P(i), or 5-10 mM arsenate, or 10-20 mM vanadate. A low basal level of AK activity (1-5% of maximal) observed in the absence of these ions is attributed to P(i) contamination in the adenine nucleotides preparations. The presence of P(i) had no effect on the K m for ATP (0.4 mM), but it markedly increased the affinity of the enzyme for adenosine. The K(m) of AK for adenosine in presence of 0, 0.1 mM and 2 mM P(i) was estimated to be 1.4 mu M, 0.77 mu M and 0.095 mu M, respectively. Free P(i) showed no exchange with any of the reactants during the assay conditions, and its presence had no effect on the thermostability of the enzyme. These observations suggest that the pentavalent ions such as phosphate may be playing an important role in the enzyme's catalytic mechanism by facilitating either binding of adenosine to the enzyme or in the formation of an enzyme-ATP-adenosine complex.

Recombinant human transforming growth factor beta does not inhibit the effects of interleukin-1 beta on pancreatic islet cells

The macrophage-derived cytokine, interleukin-1 beta (IL-1 beta), has been implicated to play an important role in the autoimmune beta cell lesion of insulin-dependent diabetes mellitus (IDDM) because of its inhibition of insulin secretion, direct cytotoxicity, and alteration of islet cell antigen expression. Because transforming growth factor beta (TGF-beta) has been reported to inhibit IL-1 receptor expression in several lymphoid and progenitor cell lines, to induce IL-1 receptor antagonist protein (IRAP) production in human peripheral blood monocytes, and to antagonize several effects of inflammatory cytokines and because oral tolerance may be mediated in part by TGF-beta released by regulatory T lymphocytes, we investigated whether TGF-beta counteracted the effects of IL-1 beta on islet cells. Islets isolated from Sprague-Dawley rats were cultured with or without recombinant human IL-1 beta and TGF-beta. Accumulated insulin secretion, cytokine-induced cytotoxicity, and islet cell expression of glutamic acid decarboxylase 65 (GAD-65) and heat-shock protein 70 (HSP-70) were measured in this study. We found that (1) IL-1 beta at 50 and 100 pg/ml inhibited insulin secretion by 41.9 +/- 14.8 and 52.6 +/- 3.5% and induced cytotoxicity by 46.5 +/- 17.3 and 54.1 +/- 6.1%, respectively. IL-1 beta at 1000 pg/ml significantly increased HSP-70 expression and decreased GAD-65 expression. (2) TGF-beta at 0.1, 1, 10, and 40 ng/ml had no significant effect on insulin secretion and did not induce cytotoxicity, TGF-beta at 40 ng/ml had no effect on the expression of either HSP-70 or GAD-65. (3) In combination, TGF-beta at 1, 10, and 40 ng/ml did not antagonize the IL-1 beta (50 and 100 pg/ml)-induced inhibition of insulin secretion or cytotoxicity; TGF-beta (40 ng/ml) did not block the effects of IL-1 beta (1000 pg/ml) on HSP-70 or GAD-65 expression. In conclusion, recombinant human TGF-beta does not counteract these effects of recombinant human IL-1 beta on rat pancreatic islet cells.

The effect of cytokines on expression of glutamic acid decarboxylase-65 in cultured islets

Insulin dependent diabetes mellitus (IDDM) is an autoimmune disease characterized by lymphocytic infiltration of the pancreatic islets (insulitis). Cytokines released as part of the insulitis process have been suggested to play an important role in the beta cell lesion of IDDM. A possible diabetogenic effect of cytokines may be mediated by their inducing abnormal expression of islet cell autoantigens. Since glutamic acid decarboxylase-65 (GAD-65) is a target autoantigen in IDDM, we investigated whether the cytokines IL-1 beta, TNF alpha IFN gamma altered islet cell expression of GAD-65 and whether the effect of cytokines on GAD-65 expression was similar to their effect on insulin secretion. We found that: 1) IL-1 beta at low dose (1 U/ml) which stimulated insulin secretion, had no effect on GAD-65 expression, whereas higher doses of IL-1 beta (10, 100, 1000 U/ml) which inhibited insulin secretion, decreased GAD-65 expression. 2) TNF alpha at doses of 10, 100, 1000 U/ml which stimulated insulin secretion had no effect on GAD-65 expression. 3) IFN gamma at doses of 10, 100, 1000 U/ml had no effect on insulin secretion or on GAD-65 expression. 4) In combination, IL-1 beta plus TNF alpha and IFN gamma showed a similar inhibitory effect on GAD-65 expression as IL-1 beta alone. In summary: 1) IL-1 beta dramatically inhibits GAD-65 expression. 2) TNF alpha and IFN gamma have no effect on GAD-65 expression. Of these three cytokines, IL-1 beta is the primary cytokine affecting GAD-65 expression.

A human opsin-related gene that encodes a retinaldehyde-binding protein

The ligand-binding property of a cytoplasmic membrane-bound protein from bovine retinal pigment epithelium (RPE) has been demonstrated. The putative RPE-retinal G protein coupled receptor (RGR) covalently binds both all-trans- and 11-cis-retinal after reduction by sodium borohydride. The 32-kDa receptor binds all-trans-retinal preferentially, rather than the 11-cis isomer. The amino acid sequence of the opsin-related protein in humans is 86% identical to that of bovine RGR, and a lysine residue, analogous to the retinaldehyde attachment site of rhodopsin, is conserved in the seventh transmembrane domain of RGR in both species. The human gene that encodes the novel retinaldehyde receptor spans 14.8 kb and is split into seven exons. The structure of the gene is distinct from that of the visual pigment genes. These findings support the notion that the rgr gene represents the earliest independent branch of the vertebrate opsin gene family. A second form of human RGR in retina is predicted by alternative splicing of its precursor mRNA. This RGR variant results from the alternative use of an internal acceptor splice site in the second intron of the human gene, and it contains an insertion of four amino acids in the connecting loop between the second and thrid transmembrane domains. Since RGR binds all-trans-retinal preferentially, one of its functions may be to catalyze isomerization of the chromophore by a retinochrome-like mechanism.

Functional state of the beta cell affects expression of both forms of glutamic acid decarboxylase

Glutamic acid decarboxylase (GAD) is a candidate target autoantigen involved in the pathogenesis of insulin-dependent diabetes mellitus (IDDM). The functional state of the beta cells has been suggested to play a pathogenic role in IDDM by altering beta-cell autoantigen expression. In this study, we investigated expression of GAD-65 and GAD-67 in isolated Sprague-Dawley rat islets cultured at different glucose concentrations. Using GAD isoform-specific antibodies in an immunoblot assay, we found that expression of both GAD-65 and GAD-67 in cultured islets was glucose dependent and that increased expression of both forms of GAD correlated with increased functional state of the beta cell. Our data indicate that the functional state of the beta cell influences islet cell expression of GAD. Thus, decreasing islet cell expression of GAD by suppressing beta cells activity may have a potential role in blunting the autoimmune destruction of pancreatic islet beta cells.

Low-dose interleukin 1 and tumor necrosis factor individually stimulate insulin release but in combination cause suppression

The macrophage-derived cytokines interleukin 1 (IL-1) and tumor necrosis factor (TNF) have direct effects on pancreatic beta cells and have been hypothesized to play important roles in the autoimmune beta cell lesion of type I diabetes because of two major effects on beta cells: altered insulin secretion and beta cell cytotoxicity. High doses of IL-1 are cytotoxic to beta cells and strongly inhibit insulin release; high-dose IL-1 plus TNF acts synergically to suppress further the insulin release. In contrast, we observed that the predominant effect of low-dose IL-1 and TNF when administered separately was the stimulation of insulin release. We therefore asked whether the combination of low-dose IL-1 plus TNF would act synergistically to stimulate or suppress insulin release. Studies were performed on cultured rat islets and both insulin release and cytotoxicity (51Cr release) were measured. After 2 days of culture, increasing doses of IL-1-25, 50, 75 and 100 ng/l--caused progressively increased cytotoxicity and impaired insulin release. In contrast, the lowest dose of IL-1 tested, 10 ng/l, increased insulin release but was still slightly cytotoxic. Tumor necrosis factor at doses of 10, 25, 62.5, 75 and 100 micrograms/l also was slightly cytotoxic but increased insulin release. The augmented insulin release declined progressively with increasing TNF dose. However the combination of insulin stimulatory doses of IL-1 (10 ng/l) and TNF (62.5 micrograms/l) suppressed insulin release. The effects of these two cytokines on insulin release demonstrated a similar pattern after 4 and 6 days of culture.(ABSTRACT TRUNCATED AT 250 WORDS)

Interleukin-2 therapy of lymphoma-bearing immunosuppressed mice

In the present study, the immune status of syngeneic Balb/c animals bearing a poorly metastatic RAW117-P lymphoma and the highly malignant liver metastatic variant RAW117-H10 lymphoma were measured and compared to control animals with no known tumor. The immune status was evaluated by performing various analyses of spleen cells for the frequencies of immune cells using flow cytometry, in vitro mitogen response and in vitro NK cell-mediated cytotoxicity assays on days 6, 9 and 12 after tumor transplantation. The results of these studies indicated that from day 9 onwards, some of the immune response of the RAW117 lymphoma-bearing animals appeared to decrease compared to control animals. In order to boost the immune response of the tumor-bearing immunosuppressed animals, recombinant interleukin-2 (rIL-2) was administered to RAW117-H10 lymphoma-bearing animals. The immune status of tumor-bearing animals treated with rIL-2 was evaluated on days 5, 10 and 15 after tumor transplantation using similar analyses of spleen cells as described above. The results of these experiments indicated that IL-2 treatment increased splenic levels of cytotoxic cells, and decreased the in vivo tumorigenicity/metastasis of metastatic RAW117-H10 lymphoma cells. rIL-2 administration resulted in a significant increase in survival of tumor-bearing animals, and histological studies showed significantly lower tumor burdens in treated animals: it appears that rIL-2 has a beneficial therapeutic effect on immunosuppressive metastatic RAW117 lymphoma.

Insulin (auto)antibodies from human IDDM cross-react with retroviral antigen p73

In NOD mice, endogenous retroviruses including intracisternal type A particles (IAP) are expressed in the pancreatic beta cells. Furthermore, in these mice, insulin autoantibodies (IAA) cross-react with retroviral protein p73 (the IAP gag gene product), suggesting molecular mimicry between insulin and p73. We therefore investigated whether IAA and insulin antibodies (IA) associated with human IDDM cross-reacted with p73. Fifty IAA positive sera from 30 newly diagnosed IDDM before insulin therapy and 20 non-diabetic first degree relatives of IDDM and 27 IA positive sera from insulin treated IDDM, initially defined as IAA or IA positive by radioimmunoassay, were evaluated. Binding to insulin and to p73 of these sera were analysed by ELISA. Approximately 65% of sera which bound insulin by ELISA also bound p73. Only one sample negative for insulin binding was positive for p73 binding. Preabsorption with either insulin or p73 inhibited binding to both insulin and p73. However, preabsorption with mouse hemoglobin had no effect on their binding. Repeat measurement of binding to insulin and p73 in 10 non-diabetic first degree relatives of IDDM over an average of 16.6 months showed that each individual's reactivity to insulin and to p73 was relatively stable over time. Furthermore, in different individuals, binding to p73 and to insulin was closely correlated over time. In addition, 75 healthy teenagers (IAA negative by RIA) were used as normal controls in this study. p73 binding was found in only two (2.7%) of the 75 subjects. These results indicate that approximately 65% of ELISA (+) IAA and IA subjects have antibodies which recognize both insulin and p73, suggesting that IAA and IA from some subjects recognize an epitope shared between human insulin and the murine gag gene product. This raises the possibility that for some subjects who are IAA positive, the immunizing antigen may be antigenically similar to p73, rather than insulin, and that endogenous retroviruses may be involved in human IDDM.

The functional state of the beta cell modulates IL-1 and TNF-induced cytotoxicity

Insulin-dependent diabetes is an autoimmune disease specifically targeting the pancreatic beta cells and several observations, both experimental and clinical, suggest that the interaction of the immune system with the beta cells is in part determined by the functional state of the target cells, increased beta cell activity resulting in augmented immunologic mechanisms and vice versa for suppressed beta cell activity and decreased immune attack. In this study we investigated whether cytokine induced islet cell cytotoxicity in vitro was in part dependent on the functional state of the beta cells. Cytotoxicity of cultured rat islets was induced by IL-1 (100 pg/ml) and TNF (62.5 ng/ml) individually and in combination and beta cell activity was modulated by culturing the islets in media containing 3.3, 5.5, 11, and 20 mmol/liter glucose. Both IL-1 and TNF were cytotoxic when administered individually and the combination of IL-1 and TNF was more cytotoxic than either cytokine alone. Maximum cytotoxicity was observed at 11 mmol/liter glucose with cytotoxicity being reduced at 5.5 mmol/liter glucose and further reduced at 3.3 mmol/liter glucose. Interestingly, the degree of cytotoxicity was lower in 20 mmol/liter glucose compared to 11 mmol/liter. These results firmly establish that islet cytotoxicity of IL-1 and TNF is highly dependent on the functional state of the beta cells. This suggests that during the IDDM disease process as some beta cells are destroyed, the compensatory increased activity of the remaining beta cells may increase their susceptibility to cytokine attack. Furthermore, our observations provide rational support for the use of beta cell rest as intervention therapy for IDDM.

Enhanced immunosuppressive activity associated with metastatic lymphoma cells

Earlier reports from our laboratory showed that Abelson virus-induced, highly malignant and liver metastatic RAW117-H10 cells, but not the parental, less metastatic RAW117-P cells, inhibited both T-cell and B-cell mitogen-induced proliferation of syngeneic normal murine spleen cells. Similar inhibition was also noted when RAW117-H10 cell surface molecules extracted with butanol were used instead of whole tumor cells. In this report we describe the suppressive properties of the butanol-extracted RAW117-H10 cell surface molecules on other immune functions and the isolation/purification of a molecule from RAW117-H10 cell butanol extract which shows inhibitory activity. The immunosuppressive molecules also inhibit natural killer cell-mediated cytotoxicity, lymphokine-activated killer cell-mediated cytotoxicity, and bone marrow colony-forming unit-granulocyte-macrophage colony formation, but not colony-forming unit-fibroblast colony formation. The suppressive molecules inhibit interleukin 2 production by the T-lymphocytes. One of the molecules responsible for some of the immunosuppressive activity has been isolated and purified from butanol extracts of the metastatic RAW117-H10 cells by preparative isoelectrofocusing techniques. The suppressive molecule has an isoelectric point of 4.3 with an approximate molecular weight of 70,000. Metastatic RAW117-H10 lymphoma cells therefore express immunosuppressive molecules, which may facilitate their growth and metastasis in vivo.