Changing the inhibitory specificity and function of Cucurbita maxima trypsin inhibitor-V by site-directed mutagenesis

Cucurbita maxima trypsin inhibitor-V (CMTI-V) is also a specific inhibitor of human blood coagulation factor beta-factor XIIa. A recombinant version of CMTI-V has allowed probing of roles of individual amino acid residues including the reactive site residue, lysine (P1), by site-directed mutagenesis. The K44R showed at least a 5-fold increase in inhibitory activity toward human beta-factor XIIa, while there was no change toward bovine trypsin. This result demonstrates that beta-factor-XIIa prefers an arginine residue over lysine residue, while trypsin is non-specific to lysine or arginine in its binding pocket. On the other hand, the specificity of CMTI-V could be changed from trypsin to chymotrypsin inhibition by mutation of the P1 residue to either leucine or methionine (K44L or K44M).

Dynamic canal encroachment during thoracolumbar burst fractures

In the burst fractures seen clinically, often poor correlation exists between the neurological deficit and the canal encroachment measured on post-trauma radiographic images. The purpose of the present study was to determine whether the dynamic canal encroachment during the trauma is greater than the static canal encroachment posttrauma. We successfully produced burst fractures in nine of 15 fresh human cadaveric thoracolumbar spine specimens (T11-L1). The specimens were incrementally impacted in a high-speed trauma apparatus until fracture occurred. During the trauma, dynamic canal encroachments were measured using three specially designed transducers placed in the canal at the levels of the superior end-plates of the T12 and L1 and the T12/L1 disk. After the trauma, residual static spinal canal encroachments were measured from the radiographs of the specimens that were prepared with 1.6-mm diameter steel balls lining the canal in the midsagittal plane. We found that the average canal diameter was 16.6 +/- 1.3 mm and the static canal encroachment was 18.0% of the canal diameter. The corresponding dynamic canal encroachment was 33.3%. Thus, the dynamic canal encroachment was 85% more than the static measurement. The clinical significance of this study lies in providing awareness to the clinician that the dynamic canal encroachment is significantly greater than the static canal encroachment seen on posttrauma radiographs or computed tomography scans. The finding may also explain the clinical observation of poor correlation between the canal encroachment measured radiographically and the neurological deficit.

Lymphocyte proliferation in mice congenitally deficient in T-cell receptor alpha beta + cells

In mice and humans, T cells are characterized on the basis of T-cell receptor (TcR) expression and divided into the major TcR alpha beta + and minor TcR gamma delta + populations. TcR alpha beta + cells are considered to be the primary regulators of the immune response, whereas the function of TcR gamma delta + cells is unclear. Mice congenitally deficient in TcR alpha beta-expressing cells provide an ideal model for analyzing the independent in vivo function of TcR gamma delta + cells in the absence of TcR alpha beta + cells. Here we report that lymphoid organs in TcR alpha mutant mice undergo substantial enlargement after being challenged by environmental antigens. This organ expansion can be attributed in part to increases in the relative proportions and absolute numbers of TcR gamma delta + cells, but an expansion of the recently described TcR beta + alpha - population also has a role. The expansion of the TcR gamma delta + population is polyclonal, as evidenced by the usage of multiple gamma and delta variable chain segments. Furthermore, a substantial proportion of the cells appears to be activated and these activated cells express surface activation markers. The results clearly demonstrate that TcR gamma delta + cells proliferate independently in response to a broad spectrum of challenges. Moreover, since the expansion of the lymphoid tissues and the TcR gamma delta + cell population is excessive relative to that seen in wild-type animals, one role of TcR alpha beta + cells is directly or indirectly to limit the responses of the other lymphoid components.

Alphamethrin-impregnated bed nets for malaria and mosquito control in China

A community-based intervention trial was carried out to evaluate the effectiveness of alphamethrin-impregnated bed nets for control of Plasmodium vivax malaria and its vector in an area of moderate endemicity in southern Henan province, central China in 1990. Malaria incidence was significantly lower in the intervention group than in the comparison group (2.03 vs. 3.57 per 100 person-years at risk). The protective efficacy for malaria incidence was 43%. The prevalence of malaria parasitaemia among children under 10 years old in the intervention group was about one-quarter of that in the comparison group (0.93% vs. 3.25% and 0.71% vs. 1.96% after one and 4 months use of impregnated nets, respectively). Alphamethrin-impregnated bed nets had a mass killing effect on vector mosquitoes. The outdoor person-biting density of Anopheles anthropophagus and A. sinensis decreased by 70.3% and 29.3% respectively. The density of these 2 mosquito species found resting inside treated nets was close to zero. No side effect was found among users of impregnated bed nets. Impregnation with alphamethrin was more effective on polyester than on cotton netting and residual effects lasted at least one year. Use of alphamethrin is less expensive than permethrin and deltamethrin.

Differences in immune recognition of cytochrome P4502D6 by liver kidney microsomal (LKM) antibody in autoimmune hepatitis and chronic hepatitis C virus infection

LKM-1 antibody, which characterizes a subtype of autoimmune hepatitis (AIH), is also found in some patients with chronic hepatitis C virus (HCV) infection. It has been suggested that HCV initiates autoimmunity through molecular mimicry, because there is partial identity between HCV and cytochrome P4502D6 (CYP2D6), the putative target of LKM-1. Whether CYP2D6 is the target of LKM-1 in HCV-related liver disease, however, is controversial. To clarify this issue, we have studied by phage plaque assay and Western blot the reactivity to recombinant CYP2D6, isolated from a human liver cDNA library, in 55 patients with LKM-1, 18 (14 females, median age 12 years) anti-HCV-negative, with classical AIH, and 37 (27 females, median age 52 years) anti-HCV-positive. Reactivity to CYP2D6 was found in 72% of the anti-HCV-negative, but only in 27% of the anti-HCV-positive patients (P < 0.001), although immunofluorescence LKM-1 titres were similar in the two groups. In addition, to investigate whether the antibody responsible for the LKM-1 fluorescent pattern also reacts with CYP2D6, we have determined the specificity of LKM-1 antibodies present in the supernatant of lymphoblastoid B cell lines obtained from two patients with LKM-1-positive AIH. An oligo/monoclonal antibody thus generated gave both the typical fluorescent pattern and reacted with CYP2D6. Our results show that whilst antibodies producing the characteristic LKM-1 fluorescent pattern can react with CYP2D6, not all LKM-1-positive sera do so, particularly if obtained from patients with chronic HCV infection. This suggests that LKM-1 in HCV infection recognizes epitopes or antigens different from those targeted in AIH.

Immunoglobulin synthesis and generalized autoimmunity in mice congenitally deficient in alpha beta(+) T cells

Through cognate B-cell-T-cell interactions and provision of cytokines, CD4+ T-cell antigen receptor (TCR) alpha beta+ T cells regulate immunoglobulin isotype synthesis. Murine IgG1 and IgE secretion is therefore substantially T-cell-dependent, whereas IgM and IgG3 secretion is not. Here we report that in the absence of alpha beta T cells, B cells expand, differentiate and secrete copious amounts of antibodies of 'T-dependent' isotypes. Moreover, the antibodies are reactive towards self-antigens, as in patients with systemic lupus erythematosus, so autoantibodies of 'T-dependent' type can develop without the help of CD4+ alpha beta T cells. This phenotype is not evident in mice or humans that are congenitally deficient in specific alpha beta T-cell functions, but bears comparison with B-cell hyperactivity and autoimmunity in transplant rejection and in immunodeficiencies such as AIDS.

Estimates of trace element intakes in Chinese farmers

Epidemiologic data on the average daily human dietary intake of the trace elements nickel, cadmium, molybdenum and silicon are scarce, worldwide, primarily because foods consumed vary widely over days and seasons. Available full year food allocation records for farmers in rural areas of China provide an unique opportunity to estimate dietary trace elements. In 1988, we measured the concentration of zinc, copper, iron, cadmium, nickel, molybdenum, silicon and selenium in different foods by using food samples collected from 232 villages (distributed among 21 communes). These measurements, combined with the food consumption information from existing food allocation records in each commune for an entire year, allowed us to estimate the average daily consumption of these trace elements by Chinese farmers. With one exception (an association of zinc and esophageal cancer), the variation of dietary trace elements did not show any association with mortality from several common diseases. The estimates for some of the dietary trace elements from some subpopulations were either less or more than current recommendations. No increases in mortality were found, however, from diseases normally associated with either dietary deficiencies or excesses of these elements.

Analysis of the peripheral T-cell receptor V beta repertoire in newly diagnosed patients with type I diabetes

Type I diabetes is an autoimmune disease characterised by a marked activation of peripheral T cells around the time of clinical diagnosis. Studies of T-cell antigen receptor V beta (TCRBV) gene usage in type I diabetes have been conflicting. Using a semi-quantitative polymerase chain reaction technique and flow cytometry we have investigated the TCRBV gene usage of 13 newly diagnosed patients with type I diabetes and 11 normal healthy controls. No preferential TCRBV gene usage was found between patients and controls even after matching for HLA-DR3 and/or -DR4. In addition, no significant differences in TCRBV gene usage were found between sequential samples taken over a period of up to 7 months following diagnosis. These results suggest that the TCR repertoire of these patients is heterogeneous and it is unlikely that a single 'pathogenic' T-cell clone is dominant at the clinical onset of the disease.

T cell clones generated from patients with type 1 diabetes using interleukin-2 proliferate to human islet antigens

T lymphocytes are implicated in the pathogenesis of Type 1 (insulin dependent) diabetes. Activated T lymphocytes expressing IL-2 receptors are found at increased levels in the peripheral blood in the prediabetic period, at diagnosis and for several months after the onset of the disease, but their role in the pathogenesis of the disease is not known. We have used co-culture of peripheral blood lymphocytes with IL-2 alone to selectively generate T cell clones from the in vivo activated T cell population, and examined the phenotype and antigen specificity of the clones derived. From 3 patients with newly-diagnosed Type 1 diabetes 184 clones were generated, the majority of which (39%) were CD4+TCR alpha beta+, whilst 31% were CD8+TCR alpha beta+. From 2 healthy control subjects 90 clones were obtained, of which 62% were CD4+TCR alpha beta+ and 33% were CD8+TCR alpha beta+. Antigen specificity was examined in 46 clones from the patients and 44 from the control subjects in proliferation assays, using as antigens homogenate of human islets of Langerhans, human islet membrane preparation and human liver membrane preparation. Three clones (all CD4+TCR alpha beta+) from the patients, but none from the control subjects, proliferated in a dose dependent fashion in response to stimulation with human islet homogenate presented by autologous APCs, but to neither of the other autoantigen preparations. Our results demonstrate that a relatively high proportion (7%) of T lymphocytes activated in vivo recognise human islet antigens, indicating that they may have a role in the pathogenesis of the disease.

Chemical synthesis, molecular cloning, overexpression, and site-directed mutagenesis of the gene coding for pumpkin (Curcubita maxima) trypsin inhibitor CMTI-V

The gene encoding for a pumpkin (Curcubita maxima) trypsin inhibitor CMTI-V was synthesized chemically. The synthetic gene was prepared from four overlapping oligonucleotides by overlapping extension. The synthetic gene was amplified by polymerase chain reaction, cloned into a T7 expression vector and expressed in Escherichia coli as a fusion protein. The clone, namely 70-1, encoded a fusion protein containing 7 amino acid residues of the N-terminus of the bacterial protein rho 10 and the entire 68 residues of CMTI-V. The wild-type fusion protein constituted approximately 15% of the total bacterial protein mass and was purified to homogeneity in a single step by antibody affinity chromatography. The wild-type fusion protein possesses inhibitory activity toward trypsin and beta-Factor XIIa, but to a lesser extent when compared to the natural CMTI-V. A mutant, T43A, in which threonine at position 43 (P2 position) was replaced by alanine, was constructed. This mutant showed considerably lower specific inhibitory activity toward both trypsin and beta-Factor XIIa.

The human T cell receptor V beta repertoire of normal peripheral blood lymphocytes before and after mitogen stimulation

Mitogen stimulation of T cells in vitro has been employed in the analysis of the T cell antigen receptor (TCR) repertoire and as a method of generating T cell lines and clones. It has been suspected for some time that mitogen stimulation may bias the repertoire. We have addressed this problem employing a semi-quantitative technique utilizing the polymerase chain reaction (PCR) and flow cytometry. Using this PCR method and a panel of primers to 22 V beta subgroups, the V beta repertoire of both unstimulated and phytohaemagglutinin (PHA)-stimulated peripheral T cells from eight healthy individuals was investigated. The samples were also analysed by flow cytometry using anti-V beta 2, V beta 5 and V beta 8 MoAbs. A significant increase in the expression of V beta 6, V beta 7.2 and V beta 10.1 was found in all eight samples of PHA-stimulated T cells compared with unstimulated T cells using the PCR method. In contrast, no differences were found between unstimulated and PHA-stimulated T cells by flow cytometry. These results question the validity of using mitogen-stimulated T cells to investigate TCR gene usage.

[The experimental studies of the effect of Forskolin on the lowering of intraocular pressure]

The effect of the domestic Forskolin on lowering the intraocular pressure (IOP) of rabbits was studied. The results showed that the Forskolin significantly lowered the normal IOP of rabbits and blocked the ocular hypertension induced by water load in rabbits (p < 0.01). The maximum decrease value of 2%, 1% and 0.5% of the Forskolin was 0.59. 0.36 and 0.19 kPa (1 kPa = 7.5 mmHg), which showed the noticeable dose-effect relationship. Topical ocular application of Forskolin lowered IOP in 1/2 hour, reached to a peak in 2-3 hours and remained significantly for 10 hours. The pupillary diameter did not change when IOP were reduced. Furthermore, the Forskolin had potent stimulative properties to adenylate cyclase (AC). The greater the ability of the Forskolin to stimulate AC, the stronger the effect of IOP lowering.

Elevation of activated gamma delta T cell receptor bearing T lymphocytes in patients with autoimmune chronic liver disease

To study the possible role of T cells bearing the gamma delta T cell receptor (TCR) heterodimer in the pathogenesis of autoimmune chronic active hepatitis (AI-CAH) and primary sclerosing cholangitis (PSC) in children, we measured levels of gamma delta+ T cells in the peripheral blood, assessed the proportion of cells bearing the disulphide-linked (BB3+) and non-disulphide-linked (A13+) subtypes of the receptor, and studied the co-expression of TCR-gamma delta and the activation markers HLA-DR and IL-2 receptor (IL-2R), and the memory cell marker CD45RO. Percentage levels and absolute numbers of gamma delta +T cells were higher in both groups of patients than in controls (P less than 0.01), mainly as a result of an increase in both percentage levels and absolute numbers of the A13+ subtype (P less than 0.001). Co-expression of IL-2R and TCR-gamma delta was not found in controls but was present in some patients with AI-CAH (four out of 17) and PSC (six out of 12) at low levels (median 2.3%, range 1.7-5.0%). Expression of HLA-DR on gamma delta+ T cells was similar in both groups of patients and controls. The majority of gamma delta+ T cells in children with AI-CAH and PSC also expressed CD45RO (74.7 +/- 18.4% and 79.8 +/- 24.3%, respectively) at levels significantly higher than in controls (53.3 +/- 17.2%, P less than 0.01). These results suggest that autoimmune liver diseases in children are associated with an expansion and activation of gamma delta+ T cells in the peripheral blood, which may be important in the pathogenesis of these disorders.

Coding assignments of the genome of adult diarrhea rotavirus

Adult diarrhea rotavirus (ADRV) has caused epidemics of diarrhea in China since 1982 and remains the only group B rotavirus associated with widespread disease in humans. We recently characterized the proteins of ADRV and have now proceeded to identify the gene segments encoding each protein. Viral RNA transcripts were synthesized in vitro with the endogenous viral RNA polymerase and separated by electrophoresis in agarose. The individual transcripts were translated in a cell-free system using nuclease-treated rabbit reticulocyte lysates. The translation products were compared with polypeptides found in purified virus and were characterized by SDS-PAGE, immunoprecipitation, and Western blot analysis using antisera to double- and single-shelled virions, virus cores, and monoclonal antibodies. Furthermore, individual RNA transcripts were hybridized to total dsRNA to determine their genomic origin. Based on this analysis, the core polypeptides VP1, VP2 and VP3 are encoded by segments 1, 2, and 3, respectively. The main polypeptides in the inner capsid, VP6, and the outer capsid, VP4 and VP7, are encoded by segments 6, 4, and 8 respectively. Segments 5, 7, and 9 code for 60, 45, and 30 kDa nonstructural polypeptides. Two other nonstructural polypeptides (24 and 25 kDa) are derived from gene segment 11. Gene segment 10 codes for a 26 kDa polypeptide that is precipitated with serum to ADRV and may be a structural protein VP9. With this exception, gene coding assignments of ADRV are comparable to those of the group A rotaviruses. Our results have clear implications for further work in cloning, sequencing, and expression genes of ADRV and can provide direction towards understanding the origin and the evolution of this virus.

Rice cystatin: bacterial expression, purification, cysteine proteinase inhibitory activity, and insect growth suppressing activity of a truncated form of the protein

A cDNA clone that encodes oryzacystatin, a cysteine protease inhibitor from rice, was isolated and expressed in Escherichia coli BL-21 (DE3) using an expression plasmid under the control of a T7 RNA polymerase promoter. The construct pT7OC 9b encoded a fusion protein containing 11 amino acid residues of the NH2 terminus of the bacterial protein phi 10 and 79 residues of oryzacystatin lacking 23 NH2-terminal residues of the wild-type protein. Recombinant oryzacystatin (ROC) constituted approximately 10% of the total bacterial protein mass and was purified in a single step by anion-exchange chromatography. The inhibitory activity of ROC toward papain (Ki = 3 x 10(-8) M) was comparable with that of the naturally occurring protein isolated from rice. Caseinolytic activity in midgut homogenates from seven species of stored product insects was inhibited from 18 to 85% by ROC, whereas the same activity was inhibited from 14 to 69% by the serine proteinase inhibitor phenylmethylsulfonyl fluoride. Midguts of stored product insects apparently contain both cysteine proteinases and serine proteinases, but the relative amounts vary with the species. When fed to the red flour beetle, Tribolium castaneum, 10 wt% ROC in the diet suppressed growth approximately 35% relative to that of the control group of insects.

A novel cereal storage protein: molecular genetics of the 19 kDa globulin of rice

A lambda gt11 cDNA library, constructed from poly(A)+ RNA isolated from immature rice seed endosperm, was screened with affinity-purified antibodies against the rice storage protein called alpha-globulin (previously), or the 19 kDa globulin (our term). A positive clone was isolated and sequenced and shown to encode a 21 kDa precursor for the 19 kDa globulin, based on the identity of portions of the inferred amino acid sequence and the sequence of three cyanogen bromide peptides of the 19 kDa globulin. Analysis of genomic DNA by Southern blotting using the cDNA clone probe revealed one hybridizing band in Eco RI, Hind III, and Bam HI digests. This strongly suggests that the 19 kDa globulin is encoded by a single-copy gene. Because of its single-copy nature and its abundance of Arg and lack of Lys, the 19 kDa rice globulin appears to be a particularly attractive target for genetically engineering increased Lys content in rice seeds.

Structure of the human gene for monoamine oxidase type A

Monoamine oxidases, type A and type B, are principal enzymes for the degradation of biogenic amines, including catecholamines and serotonin. These isozymes have been implicated in neuropsychiatric disorders. Previously, cDNA clones for both MAO-A and MAO-B have been sequenced and the genes encoding them have been localized to human chromosome Xp11.23-Xp11.4. In this work, we isolated human genomic clones spanning almost all the MAOA gene from cosmid and phage libraries using a cDNA probe for MAO-A. Restriction mapping and sequencing show that the human MAOA gene extends over 70 kb and is composed of 15 exons. The exon structure of human MAOA is similar to that described by others for human MAOB. Exon 12 (bearing the codon for cysteine, which carries the covalently bound FAD cofactor) and exon 13 are highly conserved between human MAOA and MAOB genes (92% at the amino acid level). Earlier work revealed two species of MAO-A mRNA, 2.1 kb and 4.5-5.5 kb. We now report on further cDNA isolation and sequencing, which demonstrates that the longer message has an extension of 2.2 kb in the 3' noncoding region. This extended region is contained entirely within exon 15. The two messages therefore appear to be generated by the use of two alternative polyadenylation sites. Results from the present work should facilitate the mutational analysis of functional domains of MAO-A and MAO-B. Knowledge of the gene structure will also help in evaluating the role of genetic variations in MAO-A in human disease through the use of genomic DNA, which is more accessible than the RNA, as a template for PCR-amplification and sequencing.

Transient T and B cell activation after neonatal induction of tolerance to MHC class II or Mls alloantigens

The neonatal injection of semiallogeneic F1 spleen cells into newborn parental mice results in the induction of tolerance to the corresponding alloantigen (alloAg) and chimerism. In these F1 cell-injected mice, we have previously observed that this state of specific tolerance is associated with the development of a transient lupus-like autoimmune syndrome. In this study, we show that neonatal injection of mice with spleen cells differing from the host at major histocompatibility complex (MHC) class I, class II, class (I + II), or minor lymphocyte stimulating (Mls) alloAg induced a state of specific tolerance characterized by the absence of alloreactive CTL and/or Th cell responses in the spleen and the thymus of 6- to 12-week-old injected mice. However, in mice rendered tolerant to MHC class II or class (I + II) alloAg, the presence of high levels of IgG1 antibodies, of circulating immune complexes, of anti-ssDNA autoantibodies, and of tissue lesions were transiently observed. In these mice, an increased Ia Ag expression on lymphoid spleen cells was also detected at 1 wk. The elevated production of IgG1 and the overexpression of Ia Ag were almost completely prevented by treatment with an anti-IL-4 mAb. Such manifestations of B cell activation and autoimmunity were not observed in mice neonatally injected with F1 cells differing from the host only at MHC class I Ag. In mice neonatally tolerized to Mls Ag, a transient increase in IgG2a production and an overexpression of Ia Ag were detected without features of autoimmunity, and were prevented by anti-INF-gamma mAb treatment. In mice rendered tolerant to MHC class II, class (I + II), or Mls alloAg at birth, the manifestations of B cell activation were associated with the presence of in vivo-activated alloreactive CD4+ T cells in the spleen--but not the thymus--of 1-wk-old injected mice. Together, these results suggest that in mice neonatally injected with semiallogeneic F1 cells, the process of tolerance induction is not efficient during the early postnatal period, and could allow the maturation and peripheralization of some alloreactive CD4+ T cells, leading to transient B cell activation and, depending on the alloAg, to autoimmunity.

Transient T and B cell activation after neonatal induction of tolerance to MHC class II or Mls alloantigens

The neonatal injection of semiallogeneic F1 spleen cells into newborn parental mice results in the induction of tolerance to the corresponding alloantigen (alloAg) and chimerism. In these F1 cell-injected mice, we have previously observed that this state of specific tolerance is associated with the development of a transient lupus-like autoimmune syndrome. In this study, we show that neonatal injection of mice with spleen cells differing from the host at major histocompatibility complex (MHC) class I, class II, class (I + II), or minor lymphocyte stimulating (Mls) alloAg induced a state of specific tolerance characterized by the absence of alloreactive CTL and/or Th cell responses in the spleen and the thymus of 6- to 12-week-old injected mice. However, in mice rendered tolerant to MHC class II or class (I + II) alloAg, the presence of high levels of IgG1 antibodies, of circulating immune complexes, of anti-ssDNA autoantibodies, and of tissue lesions were transiently observed. In these mice, an increased Ia Ag expression on lymphoid spleen cells was also detected at 1 wk. The elevated production of IgG1 and the overexpression of Ia Ag were almost completely prevented by treatment with an anti-IL-4 mAb. Such manifestations of B cell activation and autoimmunity were not observed in mice neonatally injected with F1 cells differing from the host only at MHC class I Ag. In mice neonatally tolerized to Mls Ag, a transient increase in IgG2a production and an overexpression of Ia Ag were detected without features of autoimmunity, and were prevented by anti-INF-gamma mAb treatment. In mice rendered tolerant to MHC class II, class (I + II), or Mls alloAg at birth, the manifestations of B cell activation were associated with the presence of in vivo-activated alloreactive CD4+ T cells in the spleen--but not the thymus--of 1-wk-old injected mice. Together, these results suggest that in mice neonatally injected with semiallogeneic F1 cells, the process of tolerance induction is not efficient during the early postnatal period, and could allow the maturation and peripheralization of some alloreactive CD4+ T cells, leading to transient B cell activation and, depending on the alloAg, to autoimmunity.

T-cell-directed hepatocyte damage in autoimmune chronic active hepatitis

To investigate the function of activated T lymphocytes in autoimmune chronic active hepatitis, 7 of 15 T-cell clones from the peripheral blood of 8 patients were studied. These clones showed specificity for liver-membrane antigen with proliferation when stimulated by rabbit liver cell membranes. 6 of these clones reacted with liver-specific lipoprotein complex, and 1 clone (and 3 subclones) responded to the asialoglycoprotein receptor (ASGPR), both known targets of immune attack in autoimmune chronic active hepatitis. 2 of these clones stimulated autologous B lymphocytes to produce liver-membrane-specific autoantibodies and antibody to the ASGPR. These results suggest that liver-membrane-specific activated T lymphocytes in peripheral blood may be important in the autoimmune attack of chronic active hepatitis.

Recombinant DNA probe detecting Eperythrozoon suis in swine blood

A genomic library to Eperythrozoon suis DNA was constructed in lambda gt11, and from this library, E suis clone KSU-2 was identified as a potential diagnostic probe. In hybridization experiments that used 100-microliters samples of blood collected in chaotropic salt solutions, the KSU-2 probe hybridized strongly with purified E suis organisms and blood samples from splenectomized swine that were parasitized with E suis. However, the probe under stringent conditions did not give radiographic indications of hybridizing with equine blood DNA, bovine blood DNA infected with Anaplasma marginale, canine blood DNA infected with Ehrlichia canis, feline blood DNA infected with Haemobartonella felis, or uninfected swine blood DNA.

Autoimmune syndrome after induction of neonatal tolerance to alloantigens: analysis of the role of donor T cells in the induction of autoimmunity

The injection of (C57BL/6 x BALB/c) F1 spleen cells into BALB/c newborn mice leads to activation of persisting F1 donor B cells and development of a lupus-like syndrome in tolerized BALB/c mice. This syndrome is characterized by hypergammaglobulinaemia, high levels of anti-DNA and anti-Sm antibodies, circulating immune complexes and deposits of immunoglobulin in renal glomeruli. The role of donor T cells in this model was investigated by injecting the newborn mice with F1 cells depleted in different T cell subsets by using specific monoclonal antibodies (MoAbs). Tolerance, as shown by an absence of H-2b-specific CTL alloreactivity and persistence of immunoglobulin bearing the donor allotype were observed in mice injected with F1 cells previously depleted in the CD4+ and/or CD8+ T cell subsets as well as in those which received Thy-1+-depleted F1 spleen cells. In these mice, a typical autoimmune syndrome was found, including splenomegaly and lymphadenopathy, anti-ssDNA and anti-aortic myosin IgG antibodies and renal deposition of immunoglobulin. However, some quantitative changes were seen: the levels of anti-aortic myosin antibodies were lower in mice tolerized with CD4+-depleted F1 cells than in those receiving untreated F1 cells. Conversely, higher levels of these autoantibodies were observed in mice tolerized with CD8+-depleted F1 cells. These results suggest that mature donor T cells are not necessary neither for the establishment of neonatal tolerance to alloantigens nor for the activation of F1 donor B cells in the production of the autoimmune syndrome in tolerant mice, but they may contribute in the regulation of the expression of autoreactive B cell clones.

Investigation of an outbreak of adult diarrhea rotavirus in China

In 1987 an epidemic of diarrhea associated with adult diarrhea rotavirus (ADRV) occurred in Qinhuangdao City, China, affecting more than 200 persons and causing 2 deaths. The outbreak was introduced by a person returning from an epidemic area and was spread initially to his family members and subsequently to the entire community. Adults were at greater risk of diarrhea than children 0-4 y of age and, the duration of illness increased significantly with increasing age. ADRV was identified by ELISA and electron microscopy. The electropherotypes of all positive specimens were identical, consistent with the single point-source introduction of the virus. Seroconversion was detected in 6 of 7 ill persons with a blocking ELISA. Both asymptomatic infection and person-to-person spread identified in this epidemic suggest that current emphasis on preventing waterborne transmission may not control the introduction of ADRV into new areas. The predisposition of adults for more severe disease with ADRV is similar to the pattern observed with other enteric viruses such as the Norwalk agent and hepatitis A.

Rat ornithine decarboxylase gene. Nucleotide sequence, potential regulatory elements, and comparison to the mouse gene

Expression of ornithine decarboxylase is regulated by a variety of hormonal and other stimuli in rat cells and tissues. To study this phenomenon at the molecular level, we isolated and sequenced a cDNA-encoding rat ornithine decarboxylase and deduced its amino acid sequence. The cDNA clone was used to isolate a clone from a rat genomic library which contained the sequence of the entire rat ornithine decarboxylase gene. The gene comprised 12 exons and 11 introns and spanned 7.7 kilobases. Two polyadenylation signals (AATAAA) were located 310 and 697 base pairs 3' to the translational termination codon and were responsible for the occurrence of two hybridizing mRNA species in Northern blots of rat cells and tissues. S1 nuclease mapping suggested that there were multiple transcriptional start sites; the major one appeared to be located 2269 base pairs of genomic sequence 5' to the ATG translational initiation site, representing 274 bases of mRNA. Several potential regulatory elements were identified in the 5'-promoter regions or in the first intron: a TATA box, GC boxes, AP-1 and AP-2 binding sites, a cAMP-responsive element, a glucocorticoid regulatory element, and RNA polymerase III promoter sequences. The 5'-noncoding region of the mRNA was extremely rich in G + C; secondary structure predictions suggested that almost this entire region could form stable secondary structures, with an overall free energy of formation (delta G) of -114 kcal/mol. The potential regulatory elements identified in both the promoter region of the gene and the 5'-untranslated region of the mRNA may be involved in the complex regulation of rat ornithine decarboxylase expression.

Purification and characterization of adult diarrhea rotavirus: identification of viral structural proteins

Adult diarrhea rotavirus (ADRV) is a newly identified strain of noncultivable human group B rotavirus that has been epidemic in the People's Republic of China since 1982. We have used sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western (immuno-) blot analysis to examine the viral proteins present in the outer and inner capsids of ADRV and compared these with the proteins of a group A rotavirus, SA11. EDTA treatment of double-shelled virions removed the outer capsid and resulted in the loss of three polypeptides of 64, 61, and 41, kilodaltons (kDa). Endo-beta-N-acetylglucosaminidase H digestion of double-shelled virions identified the 41-kDa polypeptide as a glycoprotein. CaCl2 treatment of single-shelled particles removed the inner capsid and resulted in the loss of one polypeptide with a molecular mass of 47 kDa. The remaining core particle had two major structural proteins of 136 and 113 kDa. All of the proteins visualized on sodium dodecyl sulfate-polyacrylamide gel electrophoresis were antigenic by Western blot analysis when probed with convalescent-phase human and animal antisera. A 47-kDa polypeptide was most abundant and was strongly immunoreactive with human sera, animal sera raised against ADRV and against other group B animal rotaviruses (infectious diarrhea of infant rat virus, bovine and porcine group B rotavirus, and bovine enteric syncytial virus) and a monoclonal antibody prepared against infectious diarrhea of infant rat virus. This 47-kDa inner capsid polypeptide contains a common group B antigen and is similar to the VP6 of the group A rotaviruses. Human convalescent-phase sera also responded to a 41-kDa polypeptide of the outer capsid that seems similar to the VP7 of group A rotavirus. Other polypeptides have been given tentative designations on the basis of similarities to the control preparation of SA11, including a 136-kDa polypeptide designated VP1, a 113-kDa polypeptide designated VP2, 64- and 61-kDa polypeptides designated VP5 and VP5a, and several proteins in the 110- to 72-kDa range that may be VP3, VP4, or related proteins. The lack of cross-reactivity on Western blots between antisera to group A versus group B rotaviruses confirmed that these viruses are antigenically quite distinct.

A human placental cDNA clone that encodes nonhistone chromosomal protein HMG-1

From a human placental lambda gt11 cDNA library, we have isolated a cDNA clone that encodes the entire 215-residue amino acid sequence of HMG-1. Analysis of an internal sequence similarity suggests that the DNA-binding domains of HMG-1 are separated by a rather long and flexible linker segment. Southern blotting of DNA digested with BamHI indicated a highly variable number of genes (or pseudogenes) for HMG-1 in different species. Characterization of HMG-1 mRNA expression by Northern blotting showed that three mRNA species of approximately 1.0, 1.4 and 2.4 kb were expressed in all mammalian organs and cell lines examined. These included several rat organs at different stages of development. Northern analysis also suggested the occurrence of HMG-1 mRNA in an invertebrate and a plant species.

High level, cell-specific expression of ornithine decarboxylase transcripts in rat genitourinary tissues

We evaluated transcript levels for the rate-limiting enzyme in polyamine biosynthesis, ornithine decarboxylase (ODC), in rat tissues by Northern blotting and in situ hybridization histochemistry, using a rat cDNA probe. ODC transcripts were expressed at a high level, relative to levels in other tissues, in the kidney and testis of the adult rat; maximal levels of transcripts in these tissues occurred after sexual maturation had taken place, i.e. between 20 and 150 days of age. In situ hybridization histochemistry revealed high level expression in the kidney, testis, prostate, and seminal vesicles of the male rat; this high level expression was limited to certain cell types: kidney, S3 cells of the proximal convoluted tubule; prostate and seminal vesicles, glandular or luminal epithelial cells; and testis, early spermatogenic cells. High level expression of ODC mRNA disappeared from the prostate and seminal vesicle epithelial cells after castration and reappeared with testosterone treatment; in contrast, levels of kidney ODC mRNA were essentially unchanged by castration and were similar in male and female adult rats. We conclude that high level ODC mRNA expression occurs in specific cell types in the adult rat, where it appears to be regulated by both androgen-dependent and independent mechanisms.

Quantitative analysis of precursors frequency of rheumatoid factor (RF) producing human B cells

Recently, a new culture system has been devised which leads to activation, proliferation and differentiation into antibody secreting cells of at least 90% of human peripheral blood B-lymphocytes. The system uses mutant EL-4 thymoma cells of mouse origin for B cell activation and T cell/macrophage supernatant as source of cytokines (L. Wen et al., Eur. J. Immunol. 17, 887, 1987). By an ELISA system with Fc fragments as antigen and the F(ab)2 fragment of antibodies against human IgM labelled with alkaline phosphatase, we analysed the frequencies of B cells producing IgM-RFs. The mean frequency of IgM-RF producing cells in normal controls was 1/3100 (s.d. = 0.2 log; n = 5) of circulating B cells. In 2 patients with seropositive rheumatoid arthritis (RA) the frequencies were higher (1/492; 1/262), but in 2 other seropositive patients a normal (1/5540) or even a decreased (1/20000) frequency was observed. The possible relation between circulating and synovial RF producing B cells is currently being investigated.

Theoretical and practical aspects of B-cell activation: murine and human systems

We have reviewed observations which were made during studies of murine and human B-cell responses in vitro. One currently faces difficulties in drawing any clear schema as to which external signals elicit which responses (activation, proliferation, differentiation) in B cells. However, the most potent antigen-dependent or polyclonal B-cell responses in vitro occur when, in addition to various cytokines, accessory cells, serum etc., the cultures contain either a) intact T-helper cells which enter into cell-to-cell contact with B cells, or b) some B-cell "mitogen" (T-independent antigen). Murine B cells activated with LPS and anti-Ig antibodies represent a model for the study of IL2 receptor expression and function. LPS does not act on human B cells. Certain mutant EL-4 thymoma cells are potent activators of murine and human B cells via a direct cell-to-cell interaction. The majority of human B cells can be induced to proliferate and generate a few hundred antibody-secreting cells each in the presence of such thymoma cells and a mixture of cytokines. From a practical point of view, this observation should be useful in a variety of investigations such as the analysis of the human B-cell specificity repertoire.

Limiting dilution assay for human B cells based on their activation by mutant EL4 thymoma cells: total and antimalaria responder B cell frequencies

The analysis of human B cell responses at the clonal level (limiting dilution assay) is still technically difficult. In the present study we report on a culture system that leads to activation, proliferation and differentiation into antibody-secreting cells (ASC) of about 90% of B cells from peripheral blood or spleen. In this system, B cells are cultured in the presence of a mutant subclone of the mouse thymoma EL4 for B cell activation and human T cell plus macrophage supernatant as source of proliferation and differentiation factors. ASC precursors generating clonal responses of IgM only, IgM plus IgG, or IgG only occurred at a ratio of about 6:3:1. The mean clone size was 380 cytoplasmic Ig+ cells; the mean amount of Ig secreted per clone was 20 ng. Furthermore, it has been found using this system that a considerable proportion of peripheral blood B cells from individuals with a history of malaria infection could generate clones of anti-malaria (Plasmodium falciparum) ASC (range of 0.1 to 1%, n = 6). In a control group of blood donors the corresponding frequencies were 10 times lower (range of 0.01 to 0.1%, n = 9). These results show that the EL4 culture system can be applied to the investigation of the human B cell specificity repertoire and of priming effects such as result from infectious disease.

Protein kinase C-stimulated phosphorylation in vitro of a Mr 80,000 protein phosphorylated in response to phorbol esters and growth factors in intact fibroblasts. Distinction from protein kinase C and prominence in brain

In previous studies in intact 3T3-L1 fibroblasts and adipocytes, we demonstrated that the phosphorylation state of an acidic, multicomponent Mr 80,000 protein appeared to be a specific and useful marker for the activation state of protein kinase C (Blackshear, P.J., Witters, L.A., Girard, P.R., Kuo, J.F., and Quamo, S.N. (1985) J. Biol. Chem. 260, 13304-13315). In the present studies, we demonstrate that the Mr 80,000 protein from rat adipose tissue was a substrate for protein kinase C in vitro, and co-migrated on two-dimensional gels with the analogous protein from murine 3T3-L1 adipocytes labeled by exposure of intact cells to 32Pi and phorbol 12-myristate 13-acetate. Partial proteolytic maps of the two 32P-proteins were nearly identical, supporting the postulate that the sites phosphorylated by protein kinase C in vitro, and in response to phorbol 12-myristate 13-acetate in vivo, were similar or identical. Despite their similar apparent molecular weights, we were able to distinguish between the Mr 80,000 protein and protein kinase C by several physical criteria. The Mr 80,000 protein kinase C substrate was found in fractions of all rat tissues examined, but was most prominent in rat brain. Phorbol 12-myristate 13-acetate also stimulated phosphorylation of the Mr 80,000 protein in several types of cultured neuronal cells, suggesting a possible role for this protein in cholinergic neurotransmission. The Mr 80,000 protein appears to be a useful marker for protein kinase C activation in a variety of cell types.

Ionic interactions between proteins in nonequilibrium pH gradient electrophoresis: histones affect the migration of high mobility group nonhistone chromatin proteins

In two-dimensional gel electrophoresis of the high mobility group (HMG) proteins, it has proved necessary to use nonequilibrium pH gradient electrophoresis (NEPHGE) in the first dimension rather than isoelectric focusing, because of the basic character of most of the HMG proteins [D. Tyrell, P. J. Isackson, and G. R. Reeck (1982) Anal. Biochem. 119, 433-439]. In this paper it is reported that in samples that contain histones, the mobilities of HMG proteins (particularly HMG-1, HMG-2, and HMG-E) are severely distorted in NEPHGE. This presumably results from formation of complexes between histones and HMG proteins through ionic interactions. Analysis of HMG proteins by NEPHGE/sodium dodecyl sulfate-gel electrophoresis is thus precluded in samples containing histones. Our results raise the possibility of similar artifacts occurring in NEPHGE (or isoelectric focusing) analysis of other proteins with regions of high charge density.