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E H Sasso

Publications and source records attributed to E H Sasso.

26 records · Page 2Linked to original sources
PubMed1990

Prevalence and polymorphism of human VH3 genes.

To better understand heterogeneity of human VH genes, we have studied polymorphism among three homologous genes from VH3, the most complex human VH gene family. Sequence-specific oligonucleotide probes were used to identify the germ-line source of each gene. The fetally expressed gene 56p1, and the germ-line VH element 1.9III, were identified and shown to be distinct. Also identified was T5M10, a VH element that resembles 56p1 and 1.9III, and likely corresponds to the previously described germ-line gene, hv3005. The elements 56p1, 1.9III, and T5M10 were each polymorphic, and in 52 unrelated individuals, their prevalences were 62%, 92%, and 35%, respectively. Among individuals lacking the hybridization bands characteristic of 56p1, 1.9III, or T5M10, alternative RFLP or coding region sequence variants were not found. In the population studied, these three VH elements were present in five different combinations, and at least three haplotypes. The distribution of these VH elements indicated they are not alleles of a single locus, and 56p1 and 1.9III are probably not alleles of each other. These results suggest that polymorphism is commonplace among human VH3 genes, but that a limited number of conserved alleles dominate each locus. We conclude that heterogeneity in the VH germ-line repertoire may derive more from diversity of haplotypes than from diversity of alleles.

Alleles↗
PubMed1989

Human IgM molecules that bind staphylococcal protein A contain VHIII H chains.

Staphylococcal protein A (SPA) is a bacterial membrane protein which has distinct binding sites for Fc gamma and for the Fab region of some IgM, IgG, IgA, and IgE molecules. This study establishes a structure-function correlation responsible for the binding of Ig Fab regions to SPA. Binding of 24 isolated human monoclonal IgM proteins to SPA was measured in a solid phase RIA. VH and V kappa subgroups of each IgM were determined by SDS-PAGE, transfer blotting, and detection with antisera prepared against specific first framework region peptides. Binding to SPA was seen with 10 of 11 VHIII IgM, but none of the 7 VHI or 6 VHII. Similarly, polyclonal IgM fractionated on a SPA-Sepharose CL4B column showed nearly complete partition of VHIII molecules into the SPA-binding fraction, and VHI and VHII subgroup proteins into the fall-through. We conclude that SPA binding is a functional marker for VHIII H chains in human IgM molecules.

Binding Sites↗
PubMed1988

Antigenic specificities of human monoclonal and polyclonal IgM rheumatoid factors. The C gamma 2-C gamma 3 interface region contains the major determinants.

The binding site specificity of 12 monoclonal and 11 polyclonal IgM rheumatoid factors (RF) isolated from human plasma or serum has been studied. All IgM RF bound best to sites on IgG and intact Fc. The monoclonal IgM RF did not bind at all to fragments lacking the C gamma 2 or C gamma 3 domains. In contrast, low level binding to the pFc' fragment, composed of the C gamma 3 domain, was seen with seven IgM RF, mainly from patients with rheumatoid arthritis (RA). IgG1 binding appeared to be a requisite specificity of all human IgM RF. IgM RF binding to IgG3 subclass was common among the monoclonal IgM RF. Most RA polyclonal IgM RF but only 2 of the monoclonal IgM RF possessed the IgG1, 2 and 4 binding pattern. Monoclonal IgM RF which bound best to histidine-modified IgG also bound well to IgG3. The 7-kDa fragment D of staphylococcal protein A inhibited the IgG binding of most monoclonal and to a lesser degree polyclonal IgM RF. Thus, the results indicate that the C gamma 2-C gamma 3 interface region of IgG contains the predominant determinants for monoclonal and polyclonal IgM RF. For some monoclonal IgM RF the binding site, even though at the interface of the C gamma 2 and C gamma 3 domains, is not the staphylococcal protein A site. Furthermore, polyclonal IgM RF possess specificities not encountered among the monoclonal IgM RF. These specificities may have special

Animals↗
PubMed1988

Fc epitopes for human rheumatoid factors and the relationships of rheumatoid factors to the Fc binding proteins of microorganisms.

Work from our laboratories has shown that the major antigenic determinants for rheumatoid factors (RFs) are in the C gamma 2-C gamma 3 interface region of IgG in the same area that binds staphylococcal protein A (SPA). Furthermore, the Fc binding proteins of groups A, C and G streptococci as well as the Fc binding proteins induced on cell surfaces by herpes simplex virus type I also bind to the same area of IgG. These binding site similarities between RFs and the microbial Fc binding proteins suggested conformational similarities between the RF antigen combining regions and the Fc binding regions of the microbial proteins. This hypothesis was supported by the observation that antibodies to SPA bind to the antigen combining regions of most RFs as well as to the Fc binding region of the T15 group A streptococcal Fc binding protein. These findings indicate that RFs bear the conformational internal image of these microbial proteins and suggest that RFs could arise as antibodies to the idiotypic determinants on antibodies to microbial Fc binding proteins. Alternatively, microbial Fc binding proteins could present IgG to the immune system in a way that renders specific areas of the C gamma 2-C gamma 3 interface region immunogenic. These relationships between RFs and microbial Fc binding proteins may prove to be important for our understanding of the generation of RFs in rheumatoid arthritis.

Binding Sites↗
PubMed1982

Prazosin depression of baroreflex function in hypertensive man.

Prazosin is a post synaptic alpha adrenergic blocker effective in hypertension, whose hypotensive effect is unaccompanied by reflex tachycardia or hyperreninemia, nor by other evidence of increased sympathetic activity. We studied the baroreceptor reflex arc as a potential mediator of these effects. Twenty-two essential hypertensive men were treated with prazosin alone versus placebo, and experienced a blood pressure fall (from 114.8 +/- 3.6 down to 101.1 +/- 2.5 mmHg, p less than 0.005) unaccompanied by any change in heart rate, plasma renin activity, or several other indices of sympathetic nervous system activity (plasma dopamine-beta-hydroxylase activity; urinary excretion of free catecholamines and vanillyl mandelic acid; all p less than 0.1). Concomitant with the blood pressure fall, there was a significant depression of baroreflex arc sensitivity, from 11.4 +/- 2.0 ms/mmHg down to 6.6 +/- 1.9 ms/mmHg (p less than 0.05), without an associated change in cardiac vagal inhibition (291.2 +/- 46.2 versus 300.3 +/- 19.2 ms, p greater than 0.1). Baroreflex arc sensitivity depression may in part explain the lack of reflex sympathetic outflow noted during prazosin treatment of hypertension.

Adult↗
PubMedDate not supplied

Renal perfusion changes during treatment of essential hypertension: prazosin versus propranolol.

To evaluate renal hemodynamic changes during therapy of essential hypertension, we treated 12 essential hypertensives in crossover fashion, with 1 month each of placebo, prazosin, and propranolol alone. During prazosin treatment, blood pressure was normalized with preservation of glomerular filtration rate, renal plasma flow, and renal blood flow. Propranolol, however, normalized blood pressure with an associated significant decline in glomerular filtration rate, renal plasma flow, and renal blood flow. The potential mechanisms are discussed.

Adult↗