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Biomedical subjects

J P Klein

Publications and source records attributed to J P Klein.

At least 19 recordsLinked to original sources
PubMed1992

Epitope mapping of Streptococcus mutans SR protein and human IgG cross-reactive determinants, by using recombinant proteins and synthetic peptides.

alpha-Hemolytic oral streptococci are known to possess a family of cell surface cross-reactive proteins termed Ag I/II, having a molecular mass of approximately 180 to 210 kDa. These proteins are implicated in bacterial adherence to various oral tissues, and we showed recently that the SR protein, an I/II Ag-related protein, from Streptococcus mutans OMZ 175 serogroup f possesses Ag mimicry with human IgG. In this study, regions of the SR protein encoding the cross-reactive epitope(s) were analyzed by expressing selected restriction fragments from the cloned sr gene. The three SR-derived polypeptides reacted in ELISA with anti-SR rabbit IgG, whereas only the two polypeptides located along the carboxyl-terminal two thirds of the SR protein reacted with anti-human IgG rabbit IgG. In order to locate more precisely the human IgG-cross-reactive region, we synthesized six peptides, on the basis of the recently determined complete nucleotide sequence of the sr gene. Among these peptides, peptide 2, corresponding to the alanine-rich repeating amino-terminal region, peptide 3, located in the three tandem proline-rich regions, and peptide 6, located near the cell wall-spanning region, were the most interesting in term of antigenicity and immunogenicity. Anti-peptide 2, 3, and 6 rabbit IgG reacted with free SR and with cell wall-associated SR. Peptide 1, located near the amino terminus, was poorly immunogenic. Peptides 4 and 5, located in the putative human IgG-cross-reactive region, were immunogenic; however, anti-peptide 4 rabbit IgG reacted only weakly with SR or human IgG, whereas anti-peptide 5 rabbit IgG reacted strongly with SR and human IgG, and peptide 5 was recognized by anti-SR and anti-human IgG rabbit IgG. These results confirm the cell surface accessibility of this epitope and its potential participation in eliciting, in rabbits, anti-SR IgG cross-reactive with human IgG.

Amino Acid Sequence↗
PubMed1992

Radiation-free preparation for allogeneic bone marrow transplantation in adults with acute lymphoblastic leukemia.

PURPOSE: The study was undertaken to investigate the effectiveness of allogeneic bone marrow transplantation from HLA-identical siblings after preparation with busulfan and cyclophosphamide in adults with acute lymphoblastic leukemia (ALL). PATIENTS AND METHODS: Thirty-nine patients aged 15 to 42 years underwent transplantation at three different centers from November 1984 through November 1990. All patients received 16 mg/kg busulfan and 120 mg/kg cyclophosphamide as preparative therapy. Cyclosporine plus methotrexate or cyclosporine plus corticosteroids with or without methotrexate were given for prevention of graft-versus-host disease (GVHD). RESULTS: Twelve patients died of treatment-related complications, 12 patients relapsed, and 15 patients are leukemia-free survivors. For 27 patients in group 1 (first remission, second remission, first relapse), the estimated leukemia-free survival (LFS) rate is 42.3% (95% confidence interval [CI], 22.9% to 71.7%) at 3 years. For 12 patients with more advanced disease (group 2), the 1-year LFS rate is 13.5% (95% CI, 0% to 37.1%). Chronic GVHD occurred at an estimated incidence of 63.3% and developed significantly more frequently among patients who received corticosteroids for prevention of acute GVHD. Chronic GVHD was associated with a significantly lower incidence of relapse and with improved LFS rates. CONCLUSION: LFS rate in this study is comparable to that obtained with radiation-containing regimens; however, the effectiveness of this preparative regimen in ALL requires further study.

Actuarial Analysis↗
PubMed1992

Semiparametric estimation of random effects using the Cox model based on the EM algorithm.

Consider a survival experiment where individuals within a certain subset of the population share a common, unobservable, random frailty. Such a frailty could be an unobservable genetic or early environmental effect if individuals were in sibling groups or an environmental effect if individuals were grouped by households. Suppose that if the frailty, omega, is known, the Cox proportional hazards model for the observable covariates is valid with the consequence of the random effect being a multiplicative factor on the hazard rate. Assuming tht the random frailties follow a gamma distribution, estimates of the fixed and random effects are obtained by using an EM algorithm based on a profile likelihood construction. The method developed is applied to the Framingham Heart Study to examine the risks of smoking and cholesterol levels, adjusting for potential random effects.

Adult↗
PubMed1991

Treatment for acute myelocytic leukemia with allogeneic bone marrow transplantation following preparation with BuCy2.

One hundred twenty-seven patients with acute myelocytic leukemia (AML) were given busulfan 4 mg/kg on each of 4 days and cyclophosphamide 60 mg/kg on each of 2 days (BuCy2) followed by allogeneic bone marrow transplantation from an HLA-identical or one antigen disparate sibling. For 71 patients in first complete remission, 23 in second complete remission or initial relapse, and 33 patients with primary refractory disease, second or subsequent relapse, or a preceding hematologic disorder, the 3-year leukemia-free survival (LFS) is 63.1%, 32.6%, and 24.2% respectively. The actuarial probability of relapse for each group is 14.1%, 40.6%, and 61.0%. In multivariate analyses, relapse and decreased LFS were associated with advanced disease phase and with M4/M5 French-American-British classification. The LFS of first remission patients was adversely associated with a short time interval from diagnosis to transplantation. This study indicates that BuCy2 is an attractive preparative regimen for marrow transplantation in patients with AML and that prognostic factors for relapse and LFS are similar those described for regimens containing total body irradiation.

Adult↗
PubMed1991

Urinary tract injuries in multiply-injured patients: a rational guideline for the initial assessment.

In a retrospective study involving 866 multiply-injured patients we demonstrated urinary tract injuries in 72 patients (8.3 per cent), 17 (2 per cent) of which were serious. Haematuria was a frequent finding in multiply-injured patients. In patients with serious lesions of the urinary tract, more than 35 RBCs/HPF in the sediment or macroscopic haematuria were found. All major injuries were demonstrated by the emergency intravenous urogram. Ultrasonography demonstrated contusions of the kidney or bladder and ruptures of the kidneys, but was not reliable in diagnosing ruptures of the bladder. Of 155 patients with a pelvic fracture 13 (8 per cent) had lower urinary tract injuries. In all these patients the fracture was located in the pubic arch. If a retrograde urethrogram was performed in these patients all urethral lesions were detected. We propose a rational guideline, which guarantees diagnostic accuracy of serious injuries of the urinary tract after blunt trauma, while interfering as little as possible with the resuscitative and diagnostic procedures in severely injured patients.

Hematuria↗
PubMed1991

Anti-IgG antibodies in rheumatic diseases cross-react with Streptococcus mutans SR antigen.

We have previously shown that SR protein, a S. mutans major cell wall protein, as well as the recombinant protein SR (rSR) share common epitopes with human IgG. Since this antigenic mimicry could play a role in the induction of anti IgG, we have examined, in k-ELISA, the presence of antibodies reacting with S. mutans SR proteins and S. mutans whole cells in sera from 36 patients with rheumatic diseases. The majority of the 36 sera showed a high reactivity with rSR when compared with control sera. Eight highly positive sera were further purified on rSR and human IgG sorbents and tested against both rSR and IgG in ELISA and Western blotting. The affinity-purified antibodies reacted strongly with rSR, IgG and IgG Fab fragments but failed to react with IgG Fc fragment. In Western blotting the addition of unlabelled IgG abolished the reactivity of affinity-purified biotinylated antibodies with all antigens, confirming the existence of a common epitope shared by rSR and human IgG heavy chain. We show the existence in rheumatic diseases of high titres of anti-human IgG antibodies cross-reactive with S. mutans SR proteins. Those antibodies are principally IgG and react with the Fd part of the Fab fragment. We can hypothesize from the above data that this antigenic mimicry existing between S. mutans SR-related antigens and human IgG could play a role in the synthesis of at least a part of the anti-IgG antibodies present in rheumatic diseases sera.

Antibodies, Anti-Idiotypic↗
PubMed1991

A 40-kilodalton cell wall protein-coding sequence upstream of the sr gene of Streptococcus mutans OMZ175 (serotype f).

Streptococcus mutans surface proteins may be important in immunization against dental caries. We report the existence of an open reading frame of 1,005 bp that lies 1,162 bases upstream of the S. mutans OMZ175 sr gene and that encodes a cell wall-associated protein. This open reading frame codes for 335 amino acid residues. The first 18-amino acid region is predominantly hydrophobic and resembles a signal peptide, and the hydrophobic C-terminal region may function as an anchor to the bacterial cell wall. On the basis of the predicted antigenic determinants of the deduced amino acid sequence, a 16-residue synthetic peptide corresponding to the middle hydrophilic coiled region was synthesized. Antibodies raised against this synthetic peptide reacted with a protein with an apparent Mr of 40,000 that was identified by Western immunoblotting in a cell wall extract from S. mutans OMZ175. The high reactivity in an enzyme-linked immunosorbent assay of the antibodies with whole S. mutans OMZ175 cells showed that this protein was located on the bacterial cell surface. Furthermore, the antipeptide immunoglobulin G recognized an identical determinant on the cell surface of other members of the S. mutans group. However, the function of this protein is not yet known.

Amino Acid Sequence↗
PubMed1991

Activation of human monocytes by Streptococcus mutans serotype f polysaccharide: immunoglobulin G Fc receptor expression and tumor necrosis factor and interleukin-1 production.

Streptococcus mutans serotype f polysaccharide (poly f) was prepared from S. mutans whole cells by autoclaving. The poly f was purified by chromatography on DEAE Trisacryl M and Bio-Gel P100, treated with insoluble pronase, and resubjected to chromatography on DEAE Trisacryl M. Normal human blood monocytes, stimulated in vitro with purified poly f, produced extracellular tumor necrosis factor alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta) in a dose-dependent fashion as determined by a heterologous two-site sandwich enzyme-linked immunosorbent assay. Poly f also increased the expression of monocyte cell surface receptors for the Fc part of human immunoglobulin G, activity which is correlated with an increase of the phagocytic activity of the stimulated monocytes. Polymyxin B had no effect on TNF-alpha and IL-1 beta release. Neutralization assays with anti-recombinant human TNF-alpha and anti-recombinant human IL-1 beta immunoglobulin G confirmed the fact that the cytotoxic and mitogenic mediators released by the poly f-stimulated monocytes were mainly TNF-alpha and IL-1 beta.

Antigens, Differentiation↗
PubMed1990

Purification and partial characterization of rat macrophage Fc receptor and binding factor for IgA.

By using a biotinylated ligand and Western blotting techniques, a receptor (RFc alpha) and a binding factor (BF) for IgA were detected, respectively, on membrane and in the cell-free culture supernatant of rat peritoneal macrophages. Extraction of the RFc alpha was obtained by solubilization of macrophages with Nonidet P-40, and purification was performed by HPLC affinity chromatography on a column derivatized with IgA. RFc alpha is formed of two subunits, with molecular masses of 56 and 70 kDa, which are both involved in the IgA binding ability of rat peritoneal macrophages. IgABF was recovered from the cell-free supernatant of a short-term culture of rat macrophages and was affinity-purified in the same manner as RFc alpha. Like RFc alpha, IgABF retained its IgA binding activity in its native, as well as denatured form. Since the molecular masses of RFc alpha and IgABF are similar, and IgABF competes with RFc alpha for IgA binding, one can assume that IgABF probably represents a shed RFc alpha.

Animals↗
PubMed1990

Complete nucleotide sequence of the sr gene from Streptococcus mutans OMZ 175.

The nucleotide sequence encoding the SR protein of Streptococcus mutans OMZ 175 (serotype f) has been determined. The sr gene consists of 4667 bp and codes for a 171177 Da protein. Comparison of the inferred amino acid sequence with the one of PAc antigen from S. mutans MT 8148 (serotype c) indicates a 88% conservation of amino acid residues which reflects the close relatedness of both proteins. Major differences in amino acid composition are located at the C-terminal part of the sequence where only 298 amino acids of the terminal 420 are conserved.

Amino Acid Sequence↗
PubMed1990

Molecular characterization of the gene sr of the saliva interacting protein from Streptococcus mutans OMZ175.

The saliva interacting protein (74KSR) from Streptococcus mutans serotype f, which is immunologically related to antigen I/II from serotype c, also termed B, P1, PAc, is probably involved in the adherence process of Strep. mutans to the tooth surface. A solid-phase adherence assay showed that 38% of the binding of salivary glycoproteins to Strep. mutans OMZ175 was due to this protein. We have cloned and sequenced the 74KSR gene (sr), which produces a recombinant protein (rec195K) with a relative molecular mass of 195,000, as estimated by SDS-PAGE. The strong immunological relationship and functional identity of the 74KSR and rec195K indicate that the Mr 195K protein is probably a precursor form, post-translationally processed, of the 74KSR produced in Strep. mutans. The gene sr consists of 4667 bp and codes for a 171,177 Mr protein. Biochemical features of the protein (density in proline residues and hydrophobicity) may explain the difference observed between the SDS-PAGE estimated molecular mass of the immature protein and the one deduced from the nucleotide sequence. Intra-species hybridization experiments using three contiguous restriction fragments isolated from gene sr as probes showed that the sequence is highly similar in strains from serotypes c and e. We have also shown that a fraction of the heart specific antibodies induced in rabbits during immunization with the 74KSR or rec195K reacts predominantly with human IgG and suggest the hypothesis of antigen mimicry as an explanation for the production of anti-IgG autoantibodies. It will be of great importance to identify the cross-reactive epitopes within the molecule before considering its use in protective immunization against oral streptococci.

Amino Acid Sequence↗
PubMed1990

Immunolabelling of SR protein and serotype polysaccharide in Streptococcus mutans.

Immunoelectron microscopy was used to determine the accessibility of gold-labelled monoclonal antibodies, specific for the SR protein and serotype polysaccharide, to the surface of viable cells of Streptococcus mutans. The results indicate that both antigens are simultaneously accessible to their respective antibodies.

Antibodies, Monoclonal↗
PubMed1990

A partially parametric estimator of survival in the presence of randomly censored data.

Many biological or medical experiments have as their goal to estimate the survival function of a specified population of subjects when the time to the specified event may be censored due to loss to follow-up, the occurrence of another event that precludes the occurrence of the event of interest, or the study being terminated before the event of interest occurs. This paper suggests an improvement of the Kaplan-Meier product-limit estimator when the censoring mechanism is random. The proposed estimator treats the uncensored observations nonparametrically and uses a parametric model only for the censored observations. One version of this proposed estimator always has a smaller bias and mean squared error than the product-limit estimator. An example estimating the survival function of patients enrolled in the Ohio State University Bone Marrow Transplant Program is presented.

Biometry↗
PubMed1989

Human IgG and Streptococcus mutans SR protein contain cross-reactive epitopes.

Antigen B, a glycoprotein present on the cell surface of "mutans streptococci," mediates bacterial adherence to teeth surfaces and has been implicated in cross-reactivity with human heart components. Elevated levels of anti-IgG antibodies were generally found in sera of rabbits immunized with protein SR, a B-related protein from Streptococcus mutans serogroup f, or recombinant protein SR (rSR). These anti-IgG antibodies could be involved in the previously mentioned heart cross-reactivities. Results from immunoblots and ELISA analyses demonstrate that these anti-IgG antibodies recognize common epitopes on SR, rSR, and human IgG2 and IgG4 probably located on the Fab region. Furthermore, control experiments with biotinylated human IgG show that the cross-reactions between IgG and SR were not mediated by an FcR mechanism. Direct competition between rSR and human IgG in binding to anti-IgG or anti-SR antibodies confirm that S. mutans SR protein possesses Ag mimicry with human IgG. Our studies provide some evidence that S. mutans SR protein and human IgG H chains share autoimmune epitopes which could play a role in the induction of anti-IgG antibodies and therefore could explain the enhancement of anti-IgG antibody levels observed in rabbits immunized with either S. mutans whole cells or purified B-related Ag.

Animals↗
PubMed1989

Purification and characterization of the expression product of the sr gene of Streptococcus mutans OMZ 175.

The subcloning in pBR322 of the gene of the S. mutans OMZ 175 74K SR protein, was performed after in vitro reconstitution, from two recombinant EMBL3 phages, lambda SmAD9 and lambda SmAD10. The gene is expressed in E. coli HB101 under the control of its own promoter and produces a protein with a molecular weight of 195 kDa. A strong immunological relationship between the expressed protein and the 74K SR protein was observed in ELISA, Western blotting and immunoprecipitation. The 195 kDa protein was purified by immunoaffinity chromatography to homogeneity as judged by SDS-PAGE and native PAGE. Its reactivity with monoclonal anti 74K SR antibodies indicates that it is probably a precursor form of the 74K SR protein produced in S. mutans. The adhesion properties of the two proteins, tested in solid phase adherence assays, are quite similar. This indicates that the additional peptide present in the precursor protein has little or no role in the adherence properties of protein 74K SR.

Adhesiveness↗
PubMed1989

Immunolocalization of Streptococcus mutans sr gene product in recombinant Escherichia coli.

A direct post-embedding immunogold method was used to determine the subcellular localization of the expression product of Streptococcus mutans sr gene in Escherichia coli cells. Immunolabelling was principally localized in the cytoplasm and was absent in the periplasmic space and extracellular compartment. We observed no difference in the localization of the labelling between bacteria originated from solid or liquid cultures. No difference in saliva binding could be observed between recombinant E. coli or control E. coli cells. These results showed that the cloned SR protein was not accessible at the surface of the host cell.

Bacterial Proteins↗
PubMed1989

Injuries of the lateral ankle ligaments: classification with tenography and arthrography.

To assess the value of tenography of the peroneal tendon sheaths and of arthrography of the tibiotalar joint for the diagnosis and classification of recent ruptures of the lateral ankle ligaments, the authors performed a prospective study on 108 patients with inversion trauma of the ankle. All patients underwent tenography. Arthrography was performed if results of tenography were negative. All patients with positive tenographic or arthrographic results underwent surgery. Tenography proved to be reliable in the diagnosis of injuries of the calcaneofibular ligament (sensitivity, 88%; specificity, 87%-94%). The positive predictive value of tenography in combination with arthrography was 100% for the diagnosis of lateral ligament ruptures. The authors conclude that a combination of arthrography and tenography is a reliable method for diagnosing recent ruptures of the lateral ankle ligaments and for differentiating between isolated ruptures of the talofibular ligament and combined lesions of both the talofibular and the calcaneofibular ligaments.

Adolescent↗