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Biomedical subjects

J C Hunt

Publications and source records attributed to J C Hunt.

At least 37 records · Page 2Linked to original sources
PubMed1988

Immunoglobulin G in multiple sclerosis brain.

We extracted free and bound IgG from plaques and normal-appearing white matter of multiple sclerosis (MS) brains. By isoelectric focusing (IEF), three patterns of IgG distribution were seen: (A) a restricted high-pI distribution with a specific band at low pH, (B) a restricted high-pI pattern, and (C) a broad pI pattern similar to that of the unbound IgG extracted at neutral pH. In one MS brain, we compared the IEF pattern of plaque material with that of normal-appearing white matter (NAWM); the low-pH extract of plaque material (PM) had a restricted pattern at high pI. In another MS brain, a specific band of bound IgG was found. These data suggest that MS lesions expose an antigen(s) unique to MS. B cells consequently might be stimulated by a disease-related antigen(s) in the MS lesion.

Brain↗
PubMed1988

Reliable detection of individuals seropositive for the human immunodeficiency virus (HIV) by competitive immunoassays using Escherichia coli-expressed HIV structural proteins.

We molecularly cloned the gag and env genes of the human immunodeficiency virus (HIV) and expressed fragments of these genes in Escherichia coli. Using the recombinant core and envelope proteins, we developed two competitive immunoassays (CIAs). Samples that recognized either the envelope or core proteins were considered positive for antibodies to HIV. This test system was comparable with western blot in detecting antibodies in patients with AIDS or AIDS-related complex that were repeatably reactive in the HIV screening test. All 360 individuals who were positive by western blot were positive by the CIA. A total of 844 samples repeatably reactive by an ELISA screening test were negative both by western blot and by the CIA; 48 samples positive by ELISA, but negative or indeterminate by western blot, were positive by the CIA. Alternate research procedures verified the positivity of these individuals. These data indicate that the CIA described here may be useful as an adjunct or alternative to the western blot.

AIDS-Related Complex↗
PubMed1986

Galactosyl-binding lectins from the tunicate Didemnum candidum. Purification and physicochemical characterization.

The plasma of the ascidian Didemnum candidum possesses lectin activity directed toward galactosyl moieties. We report the purification by affinity chromatography, the physicochemical properties, amino acid composition, and partial N-terminal amino acid sequence of two galactosyl-binding lectins D. candidum lectins I and II (DCL-I and DCL-II) from the plasma of this protochordate species. Both lectins were purified by affinity chromatography (on acid-treated Sepharose 4B and asialofetuin conjugated to Sepharose 4B) to homogeneity as judged by immunoelectrophoresis, size exclusion chromatography on high performance liquid chromatography, and polyacrylamide gel electrophoresis. Isoelectric focusing in polyacrylamide gels revealed that DCL-I focuses as a family of bands at pH 3.8-5.2, while DCL-II focuses at pH 9.2-10.2. Gas chromatography analyses of alditol acetate derivatives indicated that no carbohydrate components are associated with the lectins. Approximate subunit molecular weights estimated by polyacrylamide gel electrophoresis and size exclusion chromatography on high performance liquid chromatography in 6 M guanidine HCl under reducing conditions were 13,400-14,500 for DCL-I and 14,500-15,500 for DCL-II. Native molecular weights estimated by sedimentation equilibrium were 56,600 (DCL-I) and 57,500 (DCL-II), indicating that both species are constituted by four equal-sized subunits. Frictional ratios suggested that both lectins are globular proteins. Using rabbit antisera, the two molecules appeared serologically distinct. The extinction coefficient for DCL-I was E280 mg/ml = 2.52 ml mg-1 cm-1. Circular dichroism analyses of DCL-I suggested 29% alpha-helix and 37% beta-structure in the protein. Excitation/emission fluorescence spectra for DCL-I yielded maximum excitation and emission wavelengths at 288 and 330 nm, respectively. Amino acid compositions of DCL-I and DCL-II differed mainly in the proportions of aspartic and glutamic acids, serine, alanine, cysteine, valine, phenylalanine, and histidine. Amino acid compositions of DCL-I and DCL-II were compared to each other and to immunoglobulins and putative recognition molecules by the parameter S delta Q. DCL-I exhibited similarities in amino acid composition to lectins from the tunicate Halocynthia pyriformis, the lamprey Petromyzon marinus, and the horseshoe crab Carcinoscorpius rotundicauda, rabbit C-reactive protein, and lamprey and carp immunoglobulin mu chains. DCL-II showed amino acid composition and similarities with several fish immunoglobulin light chains, immunoglobulin-related molecules isolated from mouse and marmoset T cells, and carp and goldfish immunoglobulin heavy chains.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1985

Migration and wage growth: a human capital approach.

"The purpose of this paper is to analyze migration as an investment in human capital using panel data. [The authors] focus on two issues. The first is the economic motivation for migration and the reasons some movers receive high returns relative to other migrants. The second issue, and the major focus of the paper, is a test of the human capital model explaining wage profiles of nonmovers, first-time, and repeat migrants." The data are from the National Longitudinal Survey of Young Males, 1966-1971 cross-section, and concern the United States.

Americas↗
PubMed1983

Rapid molecular weight estimation and separation of selected immunoglobulin chains by high speed gel filtration.

Rapid and reliable molecular weight estimations of reduced and alkylated immunoglobulin heavy or light chains were performed by high speed gel filtration in 6 M guanidinium chloride using a short (30 cm X 7.5 mm) TSK 3000 SW type column. Molecular weight estimations based on Kav values of eluted polypeptides and glycopolypeptides were generally unaffected by protein bound carbohydrate. Rapid separation of immunoglobulin H and L chains was also achieved during high speed gel filtration.

Animals↗
PubMed1983

Some T-cell leukemia lines express surface markers related to a restricted set of human VH determinants.

Serological studies were carried out to obtain information regarding the relationship of the VH-related determinants expressed by certain permanent in vitro T-cell leukemia lines and corresponding determinants expressed by characterized human serum immunoglobulins. A panel of conventional (goat and rabbit) antisera, produced against various Fab-related fragments of monoclonal human Waldenstrom macroglobulins and polyclonal IgG molecules, bound to certain in vitro T-cell leukemia lines, notably, 70-N2, MT-1, YT4E, and HUT78, as shown by microhemagglutination. Inhibition studies using characterized myeloma proteins to inhibit this agglutination indicated the expression of a restricted VH-related determinant by these T-cell lines. Parallel studies performed using conventional (rabbit) and murine monoclonal/hybridoma antibodies produced against the isolated 68,000-Da VH-related product synthesized by the 70-N2 line showed that the determinant expressed by this molecule was restricted in expression, comprising 2-3% of the normal, polyclonal human Fab pool, and that the determinants found on the other positive T-cell leukemias were cross-reactive rather than identical. The inhibition studies suggest that the determinant resides between residue 22 and the end of the VH region. These results further define the antigenic nature of the VH-related marker found on the surfaces of certain normal and neoplastic T-cell lines.

Animals↗
PubMed1983

Antigenic and structural characteristics of an immunoglobulin-related peptide purified from marmoset T-lymphoma cells.

A 7800 Mr peptide, apparently derived from a 70,000 Mr immunoglobulin-related protein synthesized by a marmoset T-lymphoma cell line, bears immunoglobulin-related determinants apparently contained in a disulfide-bonded loop comparable to that of the VH fragment of classical H chain. A membrane-enriched, crude particulate fraction was prepared from marmoset T-lymphoma cells, and peptides generated by papain digestion of the particulate fraction were selectively purified by affinity chromatography using IgG purified from serum of a goat immunized with the Fab fragment of a human Waldenstrom macroglobulin. The smallest of the affinity-purified peptides was particularly reactive with unfractionated goat anti Fab (G alpha Fab) serum, purified IgG from G alpha Fab serum, and with antibodies affinity purified from G alpha Fab serum using Waldenstrom macroglobulins. Partial specificity of G alpha Fab antibodies was determined by competition radioimmunoassay and radioimmunoprecipitation assays. High-performance reverse-phase liquid chromatography was used for final purification of the smallest peptide which retained its reactivity with G alpha Fab serum and affinity-purified G alpha Fab antibodies. The apparent molecular weight of the peptide, determined by gel filtration in 6 M guanidine, was estimated at 3900 in its native state but increased to 7800 after reduction and alkylation, indicating a role for a disulfide bond in the tertiary structure of the peptide. The amino acid composition of the peptide was presented, and its possible relationship to immunoglobulin-like T-cell surface proteins was discussed.

Amino Acids↗
PubMed1983

Regulation of alternate peripheral pathways of glucose catabolism during aerobic and anaerobic growth of Pseudomonas aeruginosa.

Glucose may be converted to 6-phosphogluconate by alternate pathways in Pseudomonas aeruginosa. Glucose is phosphorylated to glucose-6-phosphate, which is oxidized to 6-phosphogluconate during anaerobic growth when nitrate is used as respiratory electron acceptor. Mutant cells lacking glucose-6-phosphate dehydrogenase are unable to catabolize glucose under these conditions. The mutant cells utilize glucose as effectively as do wild-type cells in the presence of oxygen; under these conditions, glucose is utilized via direct oxidation to gluconate, which is converted to 6-phosphogluconate. The membrane-associated glucose dehydrogenase activity was not formed during anaerobic growth with glucose. Gluconate, the product of the enzyme, appeared to be the inducer of the gluconate transport system, gluconokinase, and membrane-associated gluconate dehydrogenase. 6-Phosphogluconate is probably the physiological inducer of glucokinase, glucose-6-phosphate dehydrogenase, and the dehydratase and aldolase of the Entner-Doudoroff pathway. Nitrate-linked respiration is required for the anaerobic uptake of glucose and gluconate by independently regulated transport systems in cells grown under denitrifying conditions.

Aerobiosis↗
PubMed1983

Sodium intake and hypertension: a cause for concern.

Cardiovascular disease is the leading cause of death worldwide. Hypertension--the leading cause of heart attack, stroke, and kidney failure--occurs in more than 20% of adults in most modern societies. Hypertensive patients have defective sodium metabolism. From childhood throughout adult life most acculturated peoples consume 10 to 20 g of salt daily and have more obesity. Populations with low blood pressure are more active, leaner, and consume a diet low in sodium and high in potassium; however, when members of these groups are exposed to western diets, blood pressure increases with age and hypertension occurs. Drug treatment to control blood pressure prevents deaths. Conservative management, including low-sodium, high-potassium diets, restores normal blood pressure in more than half of hypertensive patients. More information on the cause and mechanisms of this condition is needed, but our primary concern is for improved nutrition and drug treatment to prevent hypertension-related cardiovascular deaths.

Adolescent↗
PubMed1982

Antigenic polypeptide fragments of a receptor related to the Fab fragment of human immunoglobulin from thymus-derived lymphocytes.

Certain thymus-derived lymphocytes of man and other primates express surface components related to the variable region of immunoglobulin heavy chains but lack constant region determinants defining any known immunoglobulin class. To obtain structural information on this molecule that can be used for comparison with known immunoglobulins and other surface molecules, we isolated the T cell-derived molecule by affinity chromatography using an antiserum raised against the monomeric Fab fragment of a human Waldenström macroglobulin and subjected the isolated molecule to either proteolysis using enzymes or cleavage with cyanogen bromide, followed by isolation of polypeptides which bore the Fab- or heavy chain variable region (VH)-related antigenic markers. The intact T cell molecule had an apparent mass of 68,000 daltons and no evidence was found for covalent or noncovalent association with polypeptides resembling light chains in apparent mass. The pattern of fragments obtained by cleavage of the T cell heavy chain suggests that the molecule is comprised of domains of approximate mass 12,000 daltons. Isolation of fragments from the digests that bear Fab-related serological markers shows that the molecule can be degraded into fragments resembling the Fd and VH of standard immunoglobulin heavy chains. A procedure was developed enabling the isolation of milligram quantities of VH-related T cell products. These results support the concept of a sharing of combining site determinants between T cell receptors and immunoglobulin heavy chains and show a general formal similarity between the two classes of molecules, even though they lack shared constant region determinants. The susceptibility of the T cell molecule to be cleaved into discrete antigenic fragments by controlled proteolysis might help to explain the plethora of sizes observed for antigen-specific T cell factors.

Animals↗