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C Kaplan

Publications and source records attributed to C Kaplan.

At least 55 records · Page 3Linked to original sources
PubMed1998

Human platelet antigen genotyping using a fluorescent SSCP technique with an automatic sequencer.

The typing of human platelet antigens (HPA) can be useful in many clinical situations such as neonatal alloimmune thrombocytopenia, post-transfusion purpura, and platelet transfusion refractoriness. The fluorescent-based single-strand conformation polymorphism (F-SSCP) technique is a fast and convenient way to perform HPA genotyping. Universal sequences from phage M13 were introduced at both ends of specific PCR-products by using 5'-tailed primers. A short second round of PCR with universal primers coupled to Cy-5 enabled the PCR-products to be fluorescently labelled. F-SSCP was performed by gel electrophoresis on an automated fluorescent DNA analyser. Genotyping of the three major HPA systems carried by the GP IIb-IIIa complex showed the F-SSCP technique to be accurate and reliable. A single gel procedure has been sufficient to detect HPA genetic polymorphisms tested to date. Neither restriction enzyme, radioactive material, nor any other hazardous chemicals such as ethidium bromide were required. This technique enabled us to genotype HPA-1, -3 and -4 alleles easily and to diagnose materno-fetal incompatibility in a rare alloantigenic system. F-SSCP is a promising technique for the detection of new mutations and/or DNA polymorphisms on a large scale.

Adult↗
PubMed1998

Report on the 1997 International Society of Blood Transfusion Workshop for Genotyping of Platelet Alloantigens. Platelet and Granulocyte Workshop ISBT.

The results from the 1997 International human platelet antigen- (HPA-) genotyping workshop are reported. Seventeen institutions participated to genotype for HPA polymorphisms of seven DNA samples. Most investigators used the polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) and PCR-sequence specific priming (SSP). A few participants applied both methods to confirm their results. All participants reported results for HPA-1, -2, -3 and -5 allotyping, while HPA-4 was determined in 12 and HPA-6 in nine laboratories, respectively. For HPA-1 to -6 there were 19 deviations from the consensus result. These deviations were not associated with any particular technique or allotype. Most frequently, however, deviation were reported for HPA-5 typing. These results were discussed at a meeting at the Joint Congress of the ISBT and the Deutsche Gesellschaft für Transfusionsmedizin und Immunhämatologie in Frankfurt, Germany, in September 1997. Based on the results and the comments, further workshops for HPA-allotyping are mandatory for quality assurance.

Antigens, Human Platelet↗
PubMed1998

Implementing a clinical pathway for congestive heart failure: experiences at a teaching hospital.

Clinical pathways are processes of care that use a multidisciplinary team effort to move patients toward a designed outcome. This article details the challenges of a Quality Enhancement and Clinical Resource Management Team in designing and implementing a successful congestive heart failure pathway at a teaching hospital. Academic institutions have the resources as part of their research mission, to enhance the development of clinical pathways and assess their outcomes.

Aged↗
PubMed1998

Severe neonatal alloimmune thrombocytopenia due to anti-HPA-3a.

BACKGROUND AND OBJECTIVES: Neonatal alloimmune thrombocytopenia is usually attributable to HPA-la antibodies. We report a case of parental platelet antigen incompatibility associated with a severe neonatal thrombocytopenia secondary to alloimmunization to HPA-3a. MATERIALS AND METHODS: Platelet antibodies were detected by the monoclonal antibody-specific immobilization of platelet antigens, genotyping of the platelets by PCR, and HLA typing by serologic procedures and PCR. RESULTS: Genotyping of maternal and paternal platelets confirmed the incompatibility in the HPA-3a system. It is noteworthy that the mother is of the HLA type DRB3*0101, is ABO-incompatible with her husband, and also has HLA class I antibodies. CONCLUSION: Severe neonatal thrombocytopenia associated with HPA-3a alloimmunization is infrequent and all the factors mentioned above could have played a role in the severity of the disease.

Adult↗
PubMed1997

Calibrating the physician. Personal awareness and effective patient care. Working Group on Promoting Physician Personal Awareness, American Academy on Physician and Patient.

Physicians' personal characteristics, their past experiences, values, attitudes, and biases can have important effects on communication with patients; being aware of these characteristics can enhance communication. Because medical training and continuing education programs rarely undertake an organized approach to promoting personal awareness, we propose a "curriculum" of 4 core topics for reflection and discussion. The topics are physicians' beliefs and attitudes, physicians' feelings and emotional responses in patient care, challenging clinical situations, and physician self-care. We present examples of organized activities that can promote physician personal awareness such as support groups, Balint groups, and discussions of meaningful experiences in medicine. Experience with these activities suggests that through enhancing personal awareness physicians can improve their clinical care and increase satisfaction with work, relationships, and themselves.

Attitude of Health Personnel↗
PubMed1997

A three amino acid deletion in glycoprotein IIIa is responsible for type I Glanzmann's thrombasthenia: importance of residues Ile325Pro326Gly327 for beta3 integrin subunit association.

Glanzmann's thrombasthenia (GT) is a recessive autosomal bleeding disorder characterized by abnormal platelet aggregation due to a qualitative or quantitative defect of the glycoprotein (GP) IIb-IIIa complex (integrin alphaIIb beta3). We describe a new mutation in the GPIIIa gene responsible for type I GT in a consanguineous Algerian family. A discordance between phenotyping and genotyping of the GPIIIa-related HPA-1 platelet alloantigen system in three family members heterozygous for the disease suggested a genetic defect in the GPIIIa gene and a normal GPIIb gene. Sequence analysis of amplified genomic DNA fragments showed a 6-bp deletion in exon 7 of the GPIIIa gene resulting in the amino acid deletion/substitution (Ile325pro326Gly327 --> Met) and creating a new BspHI restriction site. Expression of the mutated integrin beta3 subunit cDNA in Chinese hamster ovary cells showed that the cDNA gene was transcribed into a full-length beta3 protein with an apparent molecular weight identical to wild-type beta3 and accumulated as a single-chain molecule in the cell cytoplasm. The absence of heterodimeric complex formation of the mutant beta3 protein with endogenous alpha v was shown by immunoprecipitation experiments, intracellular immunofluorescent labeling, and a semiquantitative enzyme-linked immunosorbent assay using the alpha vbeta3 complex-specific monoclonal antibodies LM609 and 23C6. Substitution of the methionine residue by a proline, present at position 326 of wild-type beta3, did not restore the ability of the recombinant mutant beta3 protein to associate with alpha v , suggesting that the Ile-Pro-Gly motif is located in a beta3 domain important for integrin subunit interaction. The association of a BspHI restriction site with this newly identified mutation has allowed allele-specific restriction analysis of Algerian GT individuals and the identification of two new unrelated type I patients exhibiting the same mutation, suggesting that the described mutation might be significant in this population and that BspHI restriction analysis will provide a useful screening assay for antenatal diagnosis and genetic counselling.

Algeria↗
PubMed1997

Frequency of immune thrombocytopenia in newborns: a prospective study. Immune Thrombocytopenia Working Group.

Thrombocytopenia is a common condition in distressed newborns, but little is known about thrombocytopenia in an unselected cohort of neonates. In an attempt to address this issue, a multicenter prospective study was conducted in three obstetrical wards of AP-HP in Paris. We found the frequency of neonatal thrombocytopenia (<150 x 10(9)/L) to approximate 0.9% (48 of 5,632 appropriate samples). An immune mechanism was likely to be the cause of thrombocytopenia in 10 of the 33 cases studied, implying an incidence of 0.3% of immune neonatal thrombocytopenia in the general population. The frequency of alloimmune thrombocytopenia was 1.5/1,000 liveborn neonates, and 1/1,000 when considering anti-HPA-1a allo-immunization. Because thrombocytopenia, whatever its cause, was often silent and delayed, it appears that the only way to detect neonatal thrombocytopenia in time to prevent its potential disastrous complications would be to perform a systematic neonatal blood sampling for platelet count. All cases of ascertained thrombocytopenia should then be screened for an immune mechanism to enable early detection of autoimmune diseases in mothers and careful monitoring of subsequent pregnancies and deliveries, leading to appropriate prevention of potential severe deleterious effects in the offspring.

Adult↗
PubMed1997

HPA-10w(b) (La(a)): genetic determination of a new platelet-specific alloantigen on glycoprotein IIIa and its expression in COS-7 cells.

The heterodimeric complex glycoprotein (GP)IIb-IIIa, the fibrinogen receptor of platelets, carries numerous alloantigen systems. These polymorphisms are responsible for the immune response after transfusion or during pregnancy. In the latter case, the mother develops an antibody against an epitope present on fetal platelets, and this results in platelet destruction in the fetus. In this report, we describe the molecular characterization of a new alloantigen (La(a)) on GPIIIa responsible for neonatal alloimmune thrombocytopenia (NAIT). Using polymerase chain reaction (PCR)-single-strand conformation polymorphism (SSCP) and DNA sequencing, we found a point mutation (G to A) in a heterozygous state on the GPIIIa gene leading to amino acid substitution Arg to Gln at position 62 of the mature protein. Transient expression of GPIIb-IIIa complexes in Cos-7 cells using wild-type or mutated GPIIIa cDNA allowed us to demonstrate that this mutation was responsible for expression of the La(a) epitope.

Adult↗
PubMed1997

[Neonatal alloimmune thrombopenia in anti-HPA-3a (Baka) immunization].

BACKGROUND: Neonatal alloimmune thrombocytopenia (NAIT) in the HPA-3a system is responsible for less than 5% of all cases of NAIT. CASE REPORT: Thomas, a male infant, was born at 39 weeks of gestation after an uncomplicated pregnancy. Delivery was normal. The Apgar score was 9 at 1 minute, and 10 at 5 and 10 minutes. At 1 hour of age, he displayed extensive petechiae and purpura over the back. The platelet count was 8,000/mm3. Hematesis and extensive petechiae were noted, leading to an exchange transfusion followed by a transfusion of 0.5 U/kg of random donor platelets, 0.4 g/kg/d of intravenous immunoglobulin (IVIg) and 10 mg/kg/d of corticosteroids. IVIg were discontinued on d5 and corticosteroids on d10. There was no relapse of thrombocytopenia. A neonatal alloimmune thrombocytopenia with an HPA-3a (Baka) incompatibility was confirmed. CONCLUSION: HPA-3a incompatibility is certainly more frequent than the rare cases reported and must be searched for in all cases of neonatal thrombocytopenia.

Antigens, Human Platelet↗
PubMed1997

Analysis of CD9, CD32 and p67 signalling: use of degranulated platelets indicates direct involvement of CD9 and p67 in integrin activation.

The use of agonist monoclonal antibodies (mAbs) to probe the signalling function of platelet membrane proteins is severely limited by the dependence of the mAb effect on Fc-FcgammaRII interaction. Furthermore, in addition to its anchoring role, the FcgammaRII receptor itself generates a stimulation signal resulting in granule secretion. Platelet stimulation by the released granule contents can then further obscure the original activation signal. Here we demonstrate that these problems are largely overcome by the use of platelets which had been degranulated with thrombin prior to stimulation with mAbs. We found that, like intact cells, degranulated platelets could also be activated and induced to aggregate by mAbs against a 67 kD membrane protein (known as PTA1) and CD9, and by crosslinked CD32 (FcgammaRII). However, the signal generated by crosslinked FcgammaRII was weak compared with that induced by the other monoclonal antibodies. Thus, by diminishing the FcgammaRII signal contribution, we have succeeded for the first time to clearly dissect the target antigen signal from that generated by FcgammaRII. In addition to differences in the degree of aggregation, analysis of the signals generated by each mAb showed differences in Ca2+ fluxes and protein phosphorylation. Moreover, the signals generated by CD9 and PTA1 antigens differed significantly in their sensitivity to PKC inhibition or ADP-ribosylation of the small GTP-binding protein rhoA. Despite these differences, the signals initiated by all three antigens converged to a common signalling pathway which included activation of tyrosine kinase(s). The pattern of protein phosphorylation strongly resembled that induced by gpIIb/IIIa-mediated platelet interaction with macromolecular ligands and by mutual cell contact. The multiple intercellular links formed by mAb would have a similar effect since the Fc-receptor anchorage required for antigen stimulation is already known to be provided by adjacent cells. The present findings suggest that the function of both CD9 and PTA1 antigens is closely associated with gpIIb/IIIa activation.

Antibodies, Monoclonal↗
PubMed1997

International study to compare antigen-specific methods used for the measurement of antiplatelet autoantibodies.

Platelet-associated and plasma autoantibodies against platelet glycoproteins (GP) have been demonstrated in patients with autoimmune thrombocytopenia (AITP) using various methods. Eight laboratories in seven countries participated in this international study to evaluate the interlaboratory agreement using glycoprotein-specific immunoassays for these autoantibodies. The participating laboratories received blind samples of frozen washed platelets and plasma from 22 normal donors and 22 AITP patients. Platelet-associated and plasma autoantibodies against GPIIb-IIIa and GPIb-IX were measured by MAIPA, immunobead assay or modified antigen capture assay. Of the control samples, 96.0% and 97.2% of all results for platelet-associated and plasma autoantibodies to GPIIb-IIIa/ GPIb-IX, respectively, were negative. The mean variation coefficient of the control samples of platelet-associated and plasma autoantibodies was 89.5% (range 11.1-272.9%) and 46.5% (range 21.0-78.0%), respectively. In 20/22 patient samples, platelet-associated autoantibodies to either glycoprotein were noted by at least two laboratories. The mean degree of agreement in these samples was 74.0%. There was a significant correlation in the individual antibody measurements between all laboratories (Kendall coefficient of concordance 0.60 and 0.38, P < 0.001; Spearman rank order test, range of correlation coefficient 52.3-94.0% and 42.2-85.0%, P < 0.05, for anti-GPIIb-IIIa and anti-GPIb-IX, respectively). In contrast, plasma autoantibodies to either glycoprotein were noted by at least two laboratories in only 13/22 patient samples. Moreover, the degree of agreement was poor (50.1%) and a significant correlation was noted between only six pairs of laboratories. We conclude that methods used in this study yield good interlaboratory agreement in measuring platelet-associated autoantibodies against GPIIb-IIIa and GPIb-IX. In contrast, poor agreement was found in detecting plasma autoantibodies to the same glycoproteins.

Autoantibodies↗
PubMed1997

Spatially organized response zones in rat olfactory epithelium.

Electroolfactogram recordings were made with a four-electrode assembly from the olfactory epithelium overlying the endoturbinate bones facing the nasal septum. In this study we tested whether odors of different chemical structures produce maximal responses along longitudinally oriented regions following the olfactory receptor gene expression zones described in the literature. The distribution of responses along the dorsal-to-ventral direction of this epithelium (i.e., across the expression zones) was tested in two types of experiments. In one, four electrodes were fixed along the dorsal-to-ventral axis of one turbinate bone. In the other, four electrodes were placed in corresponding positions on four turbinate bones and moved together up toward the top of the bone. These experiments compared the odorants limonene and alpha-terpinene, which are simple hydrocarbons, with carvone and menthone, which differ from the hydrocarbons by the presence of ketone groups. All responses were standardized to an amyl acetate or ethyl butyrate standard. The responses to limonene and alpha-terpinene were often larger for the ventral electrodes. The responses to carvone and menthone were largest for the dorsal electrodes. Intermediate electrodes gave responses that were intermediate in amplitude for these odors. The possibility that direction of air flow caused the observed response distributions was directly tested in experiments with odor nozzles placed in two positions. The relatively larger dorsal responses to carvone and relatively larger ventral responses to limonene were present despite odor nozzle position. We conclude that the responses to this set of odors vary systematically in a fashion parallel to the four gene expression zones. The odorant property that governs this response distribution may be related to the presence of oxygen-containing functional groups. Certain odors evoked larger responses at the intermediate electrode sites than at other sites. Cineole was the best example of this effect. This observation shows that not all oxygen-containing functional groups produce the same effect. Although we cannot exclude other possible mechanisms, these three response gradients may be produced by the four receptor expression zones described for many of the putative olfactory receptor genes. Therefore many of the receptors in each zone may share common properties. It remains to be determined whether this zonal input is significant in central odor processing. However, the correlation of odor chemical properties with the structure of receptor molecules in each zone may provide significant leads to structure-function relationships in vertebrate olfaction.

Absorption↗
PubMed1997

[Thrombocytopenia after cardiac surgery due to anti-platelet allo-immunization. Apropos of a case].

Thrombocytopaenia is rare after cardiac surgery but carries a very high risk of bleeding and thrombotic complications. It is generally due to heparinisation but may be secondary to the surgical procedure itself (cardiopulmonary bypass, sepsis, platelet consumption by the prosthesis), or associated factors (massive blood transfusion, drug reaction, rare antiplatelet allo-immunisation). One case of post-transfusion thrombocytopenia with antiplatelet anti-HPA-la allo-antibodies with a favourable outcome with high dose polyvalent gammaglobulins is reported. The authors describe the diagnostic and therapeutic approaches to this problem.

Aged↗
PubMed1997

Practice guideline for examination of the placenta: developed by the Placental Pathology Practice Guideline Development Task Force of the College of American Pathologists.

The Placental Pathology Practice Guideline Development Task Force, a multidisciplinary group, has prepared this guideline to assist those involved with placental examination. It provides recommendations related to indications and methods for placental examination as well as sample worksheets. An algorithm for the handling of placentas summarizes the recommendations of the guideline. A summary of specific findings of placental examination together with their pathogenesis and clinical associations is also provided. Recommendations related to reporting with sample reporting formats are included. The guideline is intended as an educational tool, and its use should be guided by the individual circumstances and care setting of specific cases.

Humans↗
PubMed1996

Three secretory phospholipase A(2) genes that map to human chromosome 1P35-36 are not mutated in individuals with attenuated adenomatous polyposis coli.

Mutation of Pla2g2a, a secretory phospholipase A(2) gene, dramatically increases the number of intestinal polyps that develop in the multiple intestinal neoplasia (Min) mouse, a murine model for adenomatous polyposis coli in humans. We tested the hypothesis that mutation of the human homologue(s) of this gene might be responsible for the more severe phenotype (hundreds of polyps) seen in a subset of individuals with attenuated adenomatous polyposis coli (AAPC). DNA sequence analysis demonstrated that alterations of PLA2G2A, as well as related genes PLA2G2C and PLA2G5, were evenly distributed between three classes of AAPC subjects: those with small, intermediate, and large numbers of adenomatous colonic polyps. Among 67 additional unrelated AAPC subjects, a stop mutation in PLA2G2C did not correlate with an increased burden of adenomatous polyps. Therefore, mutation of the human homologue(s) of murine Pla2g2a does not appear to be responsible for phenotypic variation among subjects with AAPC.

Adenomatous Polyposis Coli↗