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P F Bray

Publications and source records attributed to P F Bray.

At least 73 records · Page 4Linked to original sources
PubMed1990

Identification of an abnormal gene for the GPIIIa subunit of the platelet fibrinogen receptor resulting in Glanzmann's thrombasthenia.

The platelet fibrinogen receptor, which is composed of glycoproteins IIb (GPIIb) and IIIa (GPIIIa), belongs to a large family of receptors that participate in a multitude of biologically important adhesive interactions. Platelets from most patients with the autosomal recessive bleeding disorder, Glanzmann's thrombasthenia, are deficient in GPIIb and GPIIIa. We have used cDNA probes to analyze the GPIIb and GPIIIa genes in four patients from three kindreds with Glanzmann's thrombasthenia. Southern analysis of their DNA was identical to that observed in normals when probed with a full-length GPIIb cDNA or a 3' GPIIIa cDNA. However, in one family, a 5' 2.0 kb GPIIIa cDNA identified abnormal DNA fragments in the father and two affected siblings' genes. A series of restriction digests resulting in small genomic fragments were probed with portions of the 5' 2.0 kb GPIIIa cDNA and indicated that the abnormal sequences are flanked by normal fragments of the GPIIIa gene. To analyze further the genetic defect in this family, RNA was prepared from their platelets. Northern analysis revealed normal levels of GPIIb mRNA compared to control platelets. We were unable to identify GPIIIa mRNA of any size in the clinically affected family members. We also identified an EcoRI restriction fragment length polymorphism (RFLP) that permitted carrier status determination in the clinically unaffected siblings. These studies indicate that Glanzmann's thrombasthenia can be caused by heterogeneous defects in the GPIIIa gene. Furthermore, we have shown that platelets can be used to characterize normal and abnormal GPIIIa and GPIIb mRNA, and RFLPs may be used to determine the carrier status in some families with Glanzmann's thrombasthenia. The specific gene abnormality in this family appears to represent an example of an insertional mutation resulting in a human disease.

Blood Platelet Disorders↗
PubMed1990

Carotid thrombosis following neck irradiation.

Therapeutic irradiation may accelerate atherosclerosis, increasing the risk of vascular stenosis or occlusion several to many years following radiation. However, intimal damage following irradiation may result earlier in thrombosis without stenosis. This report discusses three cases of carotid occlusion that occurred within 3 years of moderate dose irradiation. Angiographic studies showed that occlusion occurred in the absence of atherosclerotic stenosis. A review of the literature supports the conclusion that people who receive neck irradiation are at risk not only for the delayed development of diffuse atherosclerosis but also for thrombotic occlusion within months to several years. We suggest that patients who develop neurological symptoms or signs following neck irradiation, regardless of age, dose of radiation, or interval since radiation, should be evaluated for carotid or vertebral artery disease.

Adult↗
PubMed1988

Physical linkage of the genes for platelet membrane glycoproteins IIb and IIIa.

The fibrinogen receptor on human platelets is a prototypic member of the integrin family and is composed of subunit glycoproteins IIb (gpIIb) and IIIa (gpIIIa) in a 1:1 stoichiometric ratio. We have isolated cDNA clones for gpIIb and gpIIIa and localized both genes to chromosome 17. In the current study, several approaches were used to localize and map the genes for gpIIb and gpIIIa. A preliminary evaluation of subchromosomal localization was performed by using a panel of mouse-human somatic cell hybrids that contain different amounts of the long arm of human chromosome 17. Southern hybridization to the DNA of these hybrids shows that both genes map near the thymidine kinase gene. In situ hybridization to intact human chromosomes localized both genes to the 17q21-22 region. To better define the physical distance between the two genes, we examined the genomic hybridization pattern of each cDNA probe to high molecular weight restriction fragments separated by pulsed-field gel electrophoresis. Serial hybridizations of the same filter have allowed construction of long-range Mlu I and Sfi I restriction maps spanning more than 500 kilobases. Finally, nonoverlapping portions of the cDNAs for both gpIIb and gpIIIa were used to probe Sfi I digests of genomic DNA separated by field-inversion gels. This confirmed that the genes are physically linked within the same 260-kilobase Sfi I fragment and suggests that the gene for gpIIb is located on the 3' side of the gene for gpIIIa. These results suggest that coordinate expression of gpIIb and gpIIIa may depend on physical proximity.

Animals↗
PubMed1988

Cloning of glycoprotein IIIa cDNA from human erythroleukemia cells and localization of the gene to chromosome 17.

Platelet aggregation requires the binding of adhesive proteins such as fibrinogen to the heterodimer of membrane glycoproteins IIb (GPIIb) and IIIa (GPIIIa). Human erythroleukemia (HEL) cells synthesize both GPIIb and GPIIIa. Using poly(A+) RNA purified from HEL cells, we constructed a cDNA library in the lambda gt10 phage vector. This library was screened with a 38mer oligonucleotide derived from a platelet GPIIIa peptide, and three overlapping cDNAs were isolated. The three inserts encompassed 3.5 kilobases (kb), including the entire coding region of mature GPIIIa (2,286 basepairs, bp) and 1.3 kb of 3' untranslated sequence. All 222 residues determined directly from platelet GPIIIa tryptic peptides exactly matched the HEL cell-deduced amino acid sequence. The HEL cell sequence matched a previously reported endothelial cell cDNA sequence except for eight nucleotides. Five of these nucleotide differences were silent changes consistent with genetic polymorphisms. The other three differences resulted in changes in the deduced amino acid sequence of GPIIIa; reexamination of the endothelial cell cDNA sequence in these three areas revealed that it is actually identical to the HEL cell sequence. The virtual identity of the endothelial and HEL cell cDNA sequences provides direct evidence that GPIIIa is a subunit common to cell-adhesion receptors present in more than one cell type. We localized the gene for GPIIIa to chromosome 17, the same chromosome to which we had previously mapped the gene for GPIIb.

Amino Acid Sequence↗
PubMed1987

Platelet glycoprotein IIb. Chromosomal localization and tissue expression.

The GPIIb-IIIa complex functions as a receptor for cytoadhesive proteins on the platelet surface. Both GPIIb and GPIIIa are synthesized by a human erythroleukemia (HEL) cell line. We isolated several cDNA clones by screening a HEL cell cDNA library with an oligonucleotide derived from amino acid sequence of GPIIb. Nucleotide and amino acid sequences were determined from 703 bp of one of these clones. Amino acid sequence of purified platelet GPIIb peptides confirmed the identity of the clone. The cDNA encodes the carboxyl terminus of the large (alpha) subunit of GPIIb and all of the smaller (beta) subunit of GPIIb. By hybridizing the cDNA directly to chromosomes separated by dual laser chromosome sorting, the gene for GPIIb was mapped to chromosome 17. Northern blot analysis showed a approximately 3.4-kb GPIIb mRNA in HEL cells. We also compared the amino acid sequences determined from eight additional platelet GPIIb peptides with the derived amino acids from a published HEL cell GPIIb cDNA, and the platelet and HEL cell proteins appear to be the same. Despite previous reports that vascular endothelial cells and monocytes contain GPIIb, no GPIIb mRNA was observed in either type of cell. Thus, GPIIb appears to be specific for the platelet-megakaryocyte membrane and is distinct from the alpha subunits of the adhesion receptors in other normal tissues.

Amino Acid Sequence↗
PubMed1986

Biogenesis of the platelet receptor for fibrinogen: evidence for separate precursors for glycoproteins IIb and IIIa.

Congenital absence of platelet glycoproteins IIb and IIIa (GPIIb and GPIIIa) results in a severe bleeding disorder characterized by defective platelet aggregation and failure of fibrinogen to bind to platelets. GPIIb is a two-chain protein containing disulfide-linked alpha and beta subunits. GPIIb and GPIIIa are present as a heterodimeric, noncovalent complex in the platelet plasma membrane and function as the fibrinogen receptor. To characterize synthesis of these two proteins, RNA isolated from a human leukemia cell line that contains GPIIb and GPIIIa was translated in a wheat germ cell-free system. Polyclonal antibodies specific for each protein immunoprecipitated distinct [35S]methionine-labeled precursors, indicating that GPIIb and GPIIIa are translated from separate mRNAs. Moreover, using specific antibodies against either intact unreduced GPIIb or the beta subunit, we obtained evidence for synthesis of a common polypeptide precursor for GPIIb alpha and GPIIb beta. Based on experiments using microsomal membranes, it appears that GPIIb is integrated into the platelet membrane with little or no cytoplasmic component. These results suggest that precursors of GPIIb and GPIIIa may be encoded by separate genes and that each precursor is processed before delivery to the plasma membrane.

Cell Line↗
PubMed1985

Epstein-Barr nuclear antigen and viral capsid antigen antibody titers in multiple sclerosis.

To characterize the antibody response to the Epstein-Barr virus (EBV) in MS, we studied serum anti-EBV nuclear antigen (anti-EBNA) and anti-EBV capsid antigen (anti-EBVCA) titers. Both titers were assayed in 93 age- and sex-matched pairs of MS patients and controls. Anti-EBVCA titers were measured by indirect immunofluorescence and anti-EBNA titers by anticomplement immunofluorescence. The seropositivity rate of both anti-EBVCA and anti-EBNA in MS patients was 100%, compared with 84% in controls (p less than 0.0001). Both anti-EBVCA and anti-EBNA titers were significantly higher in MS patients than in controls (p less than 0.0001). The data suggest that EBV has a significant seroepidemiologic association with MS, but they do not define what role EBV antibodies play in the pathogenesis of the disease.

Adolescent↗
PubMed1983

Epstein-Barr virus infection and antibody synthesis in patients with multiple sclerosis.

We studied infectious and immune mechanisms in demyelinating disease. The clinical diagnosis in this study of 313 consecutive cases of multiple sclerosis (MS) was based on the clinical conclusions of two or more neurologists and definite abnormalities in CSF IgG. Measurement of antibodies to six microbial agents was compared in 313 patients with MS and 406 controls in the same age range. Using a standardized immunofluorescent antibody (IFA) technique, we found a significantly higher prevalence of Epstein-Barr virus (EBV) infection and a higher level of serum viral capsid antigen IgG antibody titer in the MS population than in the controls. The MS population had a lower cytomegalovirus (CMV) infection rate and lower CMV complement fixing antibody production than controls. Except for the higher measles infection rate and antibody titer in patients with MS, data on the other viruses did not differ from controls.

Antibodies, Viral↗
PubMed1983

Recurrent polyneuropathy with multiple herpesvirus infections.

A 4-year-old boy developed typical acute polyneuritis at 2 years of age and returned to fully normal status in 2 months. When he was 4 years old, an identical neurologic syndrome recurred at the same time that his sister was determined to have classic infectious mononucleosis. Both siblings then had positive Monospot tests. The boy with recurrent symmetrical neuropathy had an initial Epstein-Barr virus-viral capsid antibody (EBV-VCA) serum titer of 1:160 and this dropped to 1:40 after 1 month. A persistent complement fixation titer to cytomegalovirus (CMV) of 1:64 was measured in his serum and his concentrated CSF contained a CMV complement fixation antibody titer of 1:32, a rare finding in an age-matched control group. Cultures of his urine, buffy coat, and saliva for CMV were negative. Electrophoresis of his CSF revealed oligoclonal bands, several of which were also present in his serum. It seems most likely, but not proven, that the clinical paralysis was caused initially by a CMV infection and that the Epstein-Barr virus infection reactivated the latent CMV to produce the recurrent weakness.

Antibodies, Viral↗
PubMed1981

Progressive neurological disease associated with chronic cytomegalovirus infection.

Cytomegalovirus (CMV), the most common infectious cause of nervous system damage in the fetus and newborn infant, generally has been thought to exert its teratogenic effect during early pregnancy, and it has been assumed that clinical or postmortem abnormalities reflect static insults incurred earlier. Over the past two years we have identified two infants who presented with various clinical signs suggesting CMV infection. Serial CT head scans showed mild hydrocephalus progressing to extensive loss of brain substance and hydrocephalus in one and a normal scan going on to polycystic encephalomalacia in the other. Both infants had urine or leukocyte cultures that were repeatedly positive for CMV. These data suggest that CMV can cause progressive central nervous system damage after birth. The findings may account for some unexplained brain malformations and for a portion of the neurodegenerative disorders occurring in babies who appear normal at birth.

Brain Diseases↗
PubMed1981

Relative value of three laboratory methods in the diagnosis of multiple sclerosis.

We compared three methods of analysis for IgG in cerebrospinal fluid, using samples from 158 patients with clinically suspected multiple sclerosis and from 200 neurological controls. The tests were: search for oligoclonal bands, calculation of rate of synthesis of IgG in the cerebrospinal fluid, and determination of the IgG/albumin ratio. Paired cerebrospinal fluid and serum samples were collected and their IgG and albumin concentrations measured. Oligoclonal bands were detected by electrophoresis on agarose. Positive results were obtained in 94, 75, and 67% of patients with probable or definite multiple sclerosis by the three respective methods. In contrast, for patients for whom the clinical diagnosis of multiple sclerosis was considered possible, positive results were obtained in 10, 43, and 13%, respectively. Evidently, detection of oligoclonal bands remains the best single test for the presence of abnormal IgG in suspected multiple sclerosis patients. A combination of the first two tests is most sensitive for both probable and definite multiple sclerosis (97%) and possible multiple sclerosis (50%). Some infectious or immunologic disorders can also produce these IgG abnormalities, but they can usually be distinguished from multiple sclerosis by other clinical and laboratory data.

Diagnosis, Differential↗
PubMed1980

Cytomegalovirus and dual infection in infants.

In four unrelated infants without underlying immunodeficiency, dual infections with cytomegalovirus (CMV) and another microorganism developed. The patients included the following: (1) a 3-month-old girl with congenital CMV and perinatal cutaneous herpes simplex virus; (2) a 5-week-old girl with CMV and Pneumocystis carinii; (3) a 12-week-old girl with CMV and Haemophilus influenzae meningitis; and, (4) a 2 1/2-month-old girl with CMV and Escherichia coli meningitis. In all four cases, the patient's initial symptoms were referable not to CMV, but to the companion infecting organism. The diagnoses of CMV infection were made, respectively, by a high index of clinical suspicion in the first three cases and on the basis of a lucent parenchymal defect on computerized tomographic scan in the fourth patient. These cases provide additional evidence that CMV infection may predispose to secondary infection. We recommend that infants who have signs of infection and evidence of CNS abnormalities have cultures made for CMV. Both human CMV and experimental murine CMV infections have been associated with suppressed cellular and possibly humoral immunity.

Cytomegalovirus Infections↗
PubMed1980

Encephalopathy in young children with moderate chronic renal failure.

We studied three boys who had a similar encephalopathy develop during moderate chronic renal failure. The features included cerebellar system dysfunction, seizures, and intellectual and motor retardation. Extensive laboratory investigation failed to disclose an etiology other than chronic azotemia. These cases suggest that the developing nervous system is particularly sensitive to the effects of chronic azotemia. Early dialysis and/or transplantation should be considered in such children in an attempt to modify the serious nervous system abnormalities.

Brain Diseases↗
PubMed1980

Metrizamide ventriculography in syringomyelia.

Computed tomography (CT) both with and without contrast agents has been used to diagnose syringomyelia. We report a case in which the diagnosis was made by injection of metrizamide into a ventriculoperitoneal shunt. Continuity of the syringomyelic cavity with the ventricular system was demonstrated. This case supports the hydrodynamic concept of syringomyelia formation and illustrates a potentially useful approach to its diagnosis.

Biomechanical Phenomena↗