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Biomedical subjects

B Reid

Publications and source records attributed to B Reid.

At least 55 records · Page 3Linked to original sources
PubMed1990

DNA primase. Processivity and the primase to polymerase alpha activity switch.

Calf thymus DNA primase was examined to determine the kinetic parameters that define its unusual processivity. At 37 degrees C, the major products were 8-9 and 2-3 nucleotides long. The 2-mer was the predominant product when considered on a molar basis. At each polymerization cycle en route to synthesis of a unit length primer (7-10 nucleotides), processivity was defined by competition of enzyme dissociation with ATP binding as well as an ATP independent step(s). Reducing the temperature to 25 degrees C had relatively little effect on the production of primers less than or equal to 6 nucleotides long, but greatly enhanced production of primers twice (16-18 nucleotides) the normal unit length. Kinetic analysis revealed that synthesis of these longer primers largely involves dissociation of the primase after completion of the unit length primer. After synthesis of a primer, the primase-polymerase complex normally switches to polymerase activity. Only primers greater than or equal to 7 nucleotides long were utilized by the polymerase regardless of the dNTP concentration, indicating that the signal for the primase to polymerase activity switch is primer completion. During the switch, either the primer-template does not dissociate from the complex or the complex has extraordinarily high affinity for the primers. At 25 degrees C and physiological dNTP concentrations the activity switch is very efficient, greater than 90% of the primers are elongated. However, at 37 degrees C the switch is much less efficient, likely due to primer-template denaturation.

Adenosine Triphosphate↗
PubMed1990

DNA restriction fragment length polymorphism of HLA-DR2 haplotypes in normal individuals and in patients with rheumatoid arthritis.

A strong association between HLA-DR4 and rheumatoid arthritis (RA) has been found in a number of populations. In contrast, the incidence of DR2 is decreased in patients with RA, suggesting that this specificity may confer some protection against the disease. A number of subtypes of DR2 have been defined by serology, by responses in mixed lymphocyte culture reaction, and, more recently, by restriction fragment length polymorphism. These subtypes of DR2 are in linkage disequilibrium with different subspecificities of DQw1. It is thus likely that the distribution of these subtypic DR,DQ haplotypes in DR2 positive patients with RA may be important in understanding the genetic basis of susceptibility/resistance to RA. In this paper a study of the subtypes of DR2,DQw1 haplotypes in 18 patients with RA, who required sodium aurothiomalate as a disease remitting drug, and unrelated healthy individuals is reported. Three subtypes of DR2 haplotypes, DRw15 (Dw2),DQw1.2(DQw6), DRw15(Dw12),DQw1.12(DQw6), and DRw16(Dw21),DQw1, AZH (DQw5), were analysed with a cDNA probe for the DQ beta gene. The data show that DR2 positive patients with RA carried either the DRw15(Dw2),DQw6 or DRw15(Dw12),DQw6 haplotype. No patient with RA was positive for the DRw16(Dw21),DQw5 subspecificity. In contrast, six of 29 (21%) normal healthy DR2,DQw1 positive individuals carried the DRw16(Dw21),DQw5 haplotype. These data together with earlier results on the distribution of the DR4,DQw7 haplotype in patients with RA support the hypothesis that DQB1 chain polymorphism may be important in determining susceptibility to severe RA.

Arthritis, Rheumatoid↗
PubMed1990

Polymorphism of major histocompatibility complex extended haplotypes bearing HLA-DR3 in patients with rheumatoid arthritis with gold induced thrombocytopenia or proteinuria.

The distribution of DR3 and of extended haplotypes bearing DR3 was studied in three groups of subjects: 35 patients with rheumatoid arthritis (RA) with gold induced thrombocytopenia or proteinuria, 185 patients with RA without these side effects, and 300 normal healthy controls. The extended haplotypes bearing DR3 were analysed with cDNA probes for DR alpha, DR beta, DQ alpha, and DQ beta genes. The data showed that the prevalence of DR3 was significantly higher in patients who developed gold induced thrombocytopenia or proteinuria than in normal controls or patients with RA without these side effects. Distribution of three extended haplotypes bearing DR3 (B8, DR3; B18,DR3; non-B8,non-B18,DR3) in patients with RA with thrombocytopenia or proteinuria was significantly different from that in normal controls, but not from that in patients with RA without these toxic reactions. Southern blot analysis of DR, DQ genes with cDNA probes showed that the extended haplotype bearing B8,DR3, which carries DQA2.1 and DQB2.1 genes, was present in a significantly higher proportion of patients with RA with gold induced thrombocytopenia or proteinuria (22/24, 92%) than in patients with RA without these side effects (32/45, 71%) or normal subjects (40/61, 66%). The data suggest that the genomic region on chromosome 6 involved in susceptibility to gold induced thrombocytopenia or proteinuria should be extended to the DQA2, DQB2 gene loci.

Arthritis, Rheumatoid↗
PubMed1990

Comparative efficacy of dietary treatments on renal function in rats with sub-total nephrectomy: renal polyunsaturated fatty acid incorporation and prostaglandin excretion.

The efficacy of dietary intervention with either 6% protein restriction, fish oil or safflower oil was assessed in the remnant nephron model. Female Munich Wistar rats were prefed for one week prior to 5/6 nephrectomy and followed for the ensuing 28 days. Fish oil, safflower oil and protein restriction prevented the gammaglobulinuria but only fish oil lessened the albuminuria in this model. The remnant nephrons of the fish oil treated rats contained less arachidonic acid and greater quantities of eicosapentaenoic and docosahexaenoic acid than the safflower oil or lab chow fed control rats. The fish oil, and to a lesser extent the safflower oil, treated animals had a higher ratio of 6 keto PGF1 alpha to TX B2 metabolites in their urine. We suggest these changes may be responsible for the lessening in urine protein excretion. Fish oil feeding was more effective than severe protein restriction or safflower oil dietary supplementation in lessening both the gammaglobulinuria and albuminuria of the remnant nephron model.

6-Ketoprostaglandin F1 alpha↗
PubMed1989

Solid-phase synthesis and high-resolution NMR studies of two synthetic double-helical RNA dodecamers: r(CGCGAAUUCGCG) and r(CGCGUAUACGCG).

Ten-micromole solid-phase RNA synthesis has been successfully performed on an automated nucleic acid synthesizer with coupling efficiencies up to 99%, using the tert-butyldimethylsilyl group to protect the 2'-hydroxyl. The tert-butyldimethylsilyl group was easily removed by tetrabutylammonium fluoride under conditions in which virtually no 2'- to 3'-isomerization was found to occur. By use of this approach, the self-complementary RNA dodecamers r(CGCGAAUUCGCG) and r(CGCGUAUACGCG) were synthesized on an automated nucleic acid synthesizer, purified by TLC, and studied by high-resolution NMR. Imino protons were assigned from one-dimensional nuclear Overhauser effects. The nonexchangeable base, H1', and H2' protons were assigned by the sequential NOESY connectivity method. The NOE data from these two oligomers were analyzed qualitatively and compared to the ideal A- and B-type helix models of Arnott et al. (1972a,b). The internucleotide H6/H8 NOEs to the preceding H1' in r(CGCGUAUACGCG) were found to be sequence-dependent and probably reflect the roll angles between adjacent bases. The internucleotide H6/H8 to H2' NOEs of these oligomers correspond very well to an A-type conformation, but the interstrand adenine H2 NOEs to the following H1' were much stronger than those predicted from the fiber model. These srong interstrand NOEs can be rationalized by base pair slide to favor more interstrand base overlap, as predicted by Callidine and Drew (1984).

Base Composition↗
PubMed1989

High-resolution NMR study of a synthetic DNA-RNA hybrid dodecamer containing the consensus pribnow promoter sequence: d(CGTTATAATGCG).r(CGCAUUAUAACG).

The nonsymmetrical double-helical hybrid dodecamer d(CGTTATAATGCG).r(CGCAUUAUAACG) was synthesized with solid-phase phosphoramidite methods and studied by high-resolution 2D NMR. The imino protons were assigned by one-dimensional nuclear Overhauser methods. All the base protons and H1', H2', H2", H3', and H4' sugar protons of the DNA strand and the base protons, H1', H2', and most of the H3'-H4' protons of the RNA strand were assigned by 2D NMR techniques. The well-resolved spectra allowed a qualitative analysis of relative proton-proton distances in both strands of the dodecamer. The chemical shifts of the hybrid duplex were compared to those of the pure DNA double helix with the same sequence (Wemmer et al., 1984). The intrastrand and cross-strand NOEs from adenine H2 to H1' resonances of neighboring base pairs exhibited characteristic patterns that were very useful for checking the spectral assignments, and their highly nonsymmetric nature reveals that the conformations of the two strands are quite different. Detailed analysis of the NOESY and COSY spectra, as well as the chemical shift data, indicate that the RNA strand assumes a normal A-type conformation (C3'-endo) whereas the DNA strand is in the general S domain but not exactly in the normal C2'-endo conformation. The overall structure of this RNA-DNA duplex is different from that reported for hybrid duplexes in solution by other groups (Reid et al., 1983a; Gupta et al., 1985) and is closer to the C3'-endo-C2'-endo hybrid found in poly(dA).poly(dT) and poly(rU).poly(dA) in the fiber state (Arnott et al., 1983, 1986).

Computer Graphics↗
PubMed1989

Polymorphism of three HLA-DR7 bearing major histocompatibility complex extended haplotypes.

We have studied the complexity of HLA class II region in DR7 bearing extended haplotypes by restriction fragment length polymorphism (RFLP). Genomic DNA from homozygous cell lines and from unrelated individuals was digested with a number of restriction endonucleases and probed with DR alpha, DR beta, DQ alpha and DQ beta cDNA probes. We detected RFLPs that distinguished subspecificities of DRA, DRB1, DQA1 and DQB1 chain genes. On the basis of polymorphism in these genes, three distinct types of DR7 bearing extended haplotypes could be identified: (1) B44 or Bw47 or B14, DR7a (DRA1, B1.1), DRw53a (DRA1,B4), DQw2 (DQA1.1, B1.1); (2) B13 or B40, DR7b (DRA1, B1.2), DRw53a (DRA1, B4), DQw2 (DQA1.1, B1.1); and (3) Bw57, DR7c (DRA2, B1.2), DRw53b (DRA2, B4), DQw9 (DQA1.2, B1.2). Available evidence indicates that independent examples belonging to a haplotype were similar in RFLP patterns, suggesting that most examples of an extended haplotype belonging to a subtype are similar. The results in the present study have important implications for immune function and disease susceptibility.

Blotting, Southern↗
PubMed1989

Omega-3 fatty acid dietary supplementation in systemic lupus erythematosus.

The effect of dietary fish oil (Omega-3 fatty acids--eicosapentenoic acid [EPA] and docosahexaenoic acid [DHA] on several mechanisms involved in immune, inflammatory and atherosclerotic vascular disease was determined in 12 subjects with systemic lupus erythematosus (SLE) and nephritis. These out-patients supplemented their usual diet for five weeks with daily doses of 6 g of fish oil, followed by a five-week washout period, then five weeks of 18 g of fish oil daily. The platelet EPA content rose six-fold with the lower and 15-fold with the higher dose of fish oil, and similar changes occurred to the platelet DHA content. The platelet arachidonic acid incorporation was reduced by 16 and 20%, respectively. These changes were associated with a reduction in collagen-induced platelet aggregation and an increase in red cell flexibility and a decrease in whole blood viscosity. Prostacyclin (PGI2) production was unaffected by the fish oil, but PGI3 formation correlated with its administration and dosage. Neutrophil leukotriene B4 release was reduced 78 and 42%, respectively, by the low and higher doses of fish oil. The higher fish oil dose induced a 38% decrease in triglyceride and a 39% reduction in VLDL cholesterol associated with a 28% rise in HDL, cholesterol. The fish oil had no effect on immune complex or anti-DNA antibody titer, albuminuria, intraplatelet serotonin or [14C]-serotonin release from platelets. We conclude that in patients with lupus nephritis, dietary supplementation with fish oil affects the mechanisms involved in inflammatory and atherosclerotic vascular disease.

Adult↗
PubMed1989

Frozen shoulder and other shoulder disturbances in Parkinson's disease.

The frequency of shoulder disturbances, particularly frozen shoulder, has not been assessed previously in Parkinson's disease. In a survey of 150 patients compared with 60 matched control subjects a significantly higher incidence of both a history of shoulder complaints (43% vs. 23%) and frozen shoulder (12.7% vs. 1.7%) was found in the Parkinson's disease population. Those developing a frozen shoulder had initial disease symptoms indicative of akinesia twice as frequently as tremor while the ratio was reversed in those without frozen shoulder. In at least 8% of the patients frozen shoulder was the first symptom of disease, occurring 0-2 years prior to the onset of more commonly recognised features. Parkinson's disease should be added to the list of causes of frozen shoulder, and clinicians must be aware that the latter is often the presenting symptom of Parkinson's disease.

Activities of Daily Living↗
PubMed1987

Binding of aggregated immunoglobulins to the human platelet Fc receptors: a mechanism of platelet to platelet bridging.

Aggregated immunoglobulins react with human platelets by occupying the Fc receptors present on their surface, inducing aggregation and the release reaction. We studied the effect of heat aggregated gammaglobulins (HAGG) on ADP-induced aggregation of platelets. We used the minimum concentration of ADP required to induce a reversible aggregation of platelets without any substantial amount of serotonin (14C-5HT) release. EDTA (5 mM) added at the peak of platelet aggregation resulted in rapid deaggregation of these platelets. However, incubation of platelets with HAGG at a dose that did not by itself induce any aggregation or release reaction, followed by ADP addition resulted in an irreversible platelet aggregation of greater magnitude accompanied by a substantial release of 14C-5HT. The addition of EDTA at the peak of platelet aggregation failed to deaggregate these platelets. To determine whether the augmented aggregation response and the inhibition of deaggregation was due to HAGG or a consequence of platelet release products, we used thrombin-degranulated platelets. The augmented aggregation response and the inhibition of deaggregation due to HAGG and ADP could be demonstrated using these platelets. To confirm that the binding of HAGG to the platelet Fc receptors was responsible for these observations, we incubated platelets with an excess of Fc fragments of IgG prior to the addition of HAGG and ADP. This abolished the aggregation response observed previously. From this study we conclude that interplatelet bridging by HAGG renders the platelets hyperaggregable and appears to be a mechanism involved in maintaining platelet aggregates.

Adenosine Diphosphate↗
PubMed1987

HLA-DQ beta-chain polymorphism in HLA-DR4 haplotypes associated with rheumatoid arthritis.

With a cDNA probe for the DQ beta gene, two variants of the DR4-linked DQw3 (3.1 and 3.2) allele were analysed in patients with rheumatoid arthritis (RA), healthy individuals, and homozygous cell lines. The DQw3.1 allele, identified by 3.4 kb (HindIII), 2.3 kb (SstI), and 3.7 kb and 6.9 kb (BamHI) restriction fragment lengths, was expressed in 100% (of 18) DR4-positive patients, compared with only 19% (of 16) of DR4-positive controls including one of five homozygous cell lines. This DQ beta variant showed a highly significant association (relative risk = 78; p less than 10(-6) with RA and may therefore play an important part in susceptibility to RA.

Arthritis, Rheumatoid↗