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Biomedical subjects

L Hood

Publications and source records attributed to L Hood.

At least 379 records · Page 21Linked to original sources
PubMed1980

Partial N-terminal amino acid sequences of guinea pig classic histocompatibility antigens.

Partial N-terminal amino acid sequences were determined by microsequencing for three of the guinea pig GPLA-B classic histocompatibility antigens, which are presumably allelic products. The sequences of GPLA-B.1 derived from the noncongenic inbred strain 2 and strain 13 animals showed no differences a their N-termini, suggesting that these molecules are chemically as well as serologically identical. Two residues, isoleucine and leucine, were found at position 5 of the sequence of GPLA-B.1, suggesting that GPLA-S, the product of the second classic histocompatibility locus, was being cosequenced. GPLA-B.2 and GPLA-B.3 antigens showed distinct sequence differences from GPLA-B.1 and from each other. The sequences of GPLA-B.3 derived from a random-bred guinea pig and from the inbred DHCBA strain showed no differences and showed a possible species specific residue. All sequences showed significant homology with histocompatibility antigens of other species, suggesting a common evolutionary origin.

Amino Acid Sequence↗
PubMed1979

Partial N-terminal amino acid sequence analyses and comparative tryptic peptide maps of murine Ia molecules encoded by the I-A subregion.

The partial N-terminal amino acid sequences and tryptic peptide maps of I-A subregion products from the H-2b, H-2d, H-2k and H-2s haplotypes demonstrate that haplotype-associated differences are present in both alpha and beta polypeptides. The genetic and evolutionary implications of these multiple amino acid substitutions and the homology relationships among Ia molecules from human, guinea pig and the I-E subregion of the mouse are discussed.

Alleles↗
PubMed1979

Dynorphin-(1-13), an extraordinarily potent opioid peptide.

We describe the opioid properties of a tridecapeptide, the sequence of which corresponds to the NH2-terminal sequence of dynorphin, a novel porcine pituitary endorphin. It contains [Leu]enkephalin. In the guinea pig ileum longitudinal muscle preparation it is about 700 times more potent than [Leu]enkephalin. Its effects in this tissue are blocked completely by naloxone, but the apparent affinity of naloxone is 1/13th that for blockade of [Leu]enkephalin or normorphine. In the mouse vas deferens, this peptide is 3 times more potent than [Leu]enkephalin. Well-washed rat brain membranes degrade the peptide rapidly, suggesting the presence of a membrane-bound degradative enzyme. The peptide displays considerable immunoreactivity in assays with antisera that have been used for the immunohistochemical localization of [Leu]enkephalin. The remarkable enhancement of the potency of [Leu]enkephalin by the COOH-terminal extension -Arg-Arg-Ile-Arg-Pro-Lys-Leu-Lys-OH suggests new interpretations concerning the structure of opiate receptors and the function of the enkephalin pentapeptides.

Amino Acid Sequence↗
PubMed1979

Immunoglobulin heavy chain gene organization in mice: analysis of a myeloma genomic clone containing variable and alpha constant regions.

We have isolated a myeloma genomic DNA clone containing the variable and constant regions of a mouse alpha chain. Restriction enzyme analyses and electron microscopic R loop mapping have demonstrated that the variable region is separated from the constant region by 6.8 kilobases of intervening DNA. In addition, two intervening DNA sequences of 100--200 bases separate the constant region into three approximately equal units. These intervening sequences may separate each of the segments coding for the three constant region domains of the alpha heavy chain. Southern blot analysis of embryo and myeloma DNA suggests that DNA rearrangement of heavy chain variable and constant regions occurs during the differentiation of antibody-producing cells.

Animals↗
PubMed1979

Myeloma proteins from NZB and BALB/c mice: structural and functional differences.

Structural and functional analyses of myeloma immunoglobulins from inbred BALB/c mice and humans have provided important insights into the structure of the antibody molecule and the expression and evolution of antibody genes. One important question concerning these analyses is whether the myeloma process selects, in a nonrandom manner, the lymphocytes to be transformed. The availability of myeloma tumors in a second inbred strain of mouse, NZB, permits us to approach this question. In this respect. the NH2-terminal amino acid sequences of 27 kappa light chains as well as data relating to the antigen-binding properties and immunoglobulin class distribution of NZB myeloma proteins are presented and compared with similar data from the BALB/c mouse. These studies suggest that the myeloma proteins from the BALB/c and NZB mice constitute two populations of immunoglobulins with distinct functional and structural properties. The implication of this observation are discussed.

Amino Acid Sequence↗
PubMed1979

Comparisons of myeloma proteins from NZB and BALB/c mice: structural and functional differences of heavy chains.

The N-terminal sequences from heavy variable regions of 47 myeloma proteins of the NZB mouse have been analyzed. Sixteen of these VH regions have unblocked alpha amino groups and have been analyzed over their N-terminal 20 residues by automatic sequence analysis. These sequence data along with the antigen-binding profiles and immunoglobulin class distribution are compared with comparable data from BALB/c myeloma proteins. These comparisons suggest that the NZB and BALB/c populations of myeloma proteins are distinct from one another. The genetic implications of this conclusion are discussed.

Amino Acid Sequence↗
PubMed1979

Analysis of the diversity of murine antibodies to dextran B1355: N-terminal amino acid sequences of heavy chains from serum antibody.

The N-terminal amino acid sequences of two gamma and two mu chains from normally induced serum antibodies to dextran in BALB/c mice are presented. These heavy chains are derived from antibodies with three distinguishable idiotypes. These variable region (VH) sequences are all identical as far as they have been analyzed (27 to 53 residues). The light chains from these antibodies are all of the lambda type and are identical by isoelectric focusing analysis. Accordingly, the diversity of dextran antibodies appears to reside primarily in the heavy chains. The implications of these observations for antibody diversity are discussed.

Amino Acid Sequence↗
PubMed1979

What, when, and how about why: a longitudinal study of early expressions of causality.

Children's expressions of causality in natural discourse with adults were examined in terms of linguistic, contextual, and pragmatic influences. Specifically, the causal statements, questions, and responses to causal questions of eight 2-3-year-old children were examined in terms of developments in language content, form, and use. With respect to content, the referential and functional uses of causal expressions for both children and adults were to ongoing or imminent situations, with the speaker commenting on his or her intention to act, or requesting the listener to act. The major categories of reference in all three utterance types were negation, direction, and intention. In terms of form, there were (a) increasing use of connectives to link clauses for all the children, and (b) three main patterns of clause order differentiating among the children: cause/effect, effect/cause, and equal use of both orders. The use of expressions of causality developed in the order: child statements less than adult questions less than child responses less than child questions. The relationship of the linguistic context to these developments was found to be one of mutual influence between child and adult. The results are discussed in terms of previous hypotheses concerning (a) causal reasoning (especially those put forth by Piaget, and by Werner & Kaplan in 1963), (b) the relationship between language and conceptual development, (c) the constraints involved in different discourse situations, and (d) variation in child language.

Child Language↗
PubMed1978

Silkmoth chorion proteins: sequence analysis of the products of a multigene family.

Five polypeptide components have been isolated from the eggshell (chorions) of a silkmoth. Two are homogeneous on sodium dodecyl sulfate and isoelectric focusing gels, and three contain predominantly two proteins each. Amino acid analyses show that all five components are similar to each other. These proteins have been sequenced from the amino terminus. Homogeneous components yielded single sequences; heterogeneous components yielded two residues at some positions, consistent with their containing two major electrophoretic components. Striking similarities are apparent among all these sequences. These similarities can be increased dramatically by separating each of the three protein mixtures into two sequences and introducing a small number of gaps or insertions. This is due in part to bringing into register a portion that contains short repeating subunits found in all sequences. All proteins are also characterized by a region of high cysteine content near the amino terminus followed by a longer low-cysteine region. The data suggest that these proteins share a common evolutionary origin and are encoded by a multigene family.

Amino Acid Sequence↗
PubMed1977

The area-code hypothesis: the immune system provides clues to understanding the genetic and molecular basis of cell recognition during development.

Numberous studies of embryogenesis have provided evidence for highly specific cell-surface recognition phenomena. These include both the interactions of neighboring cells and the specific cellular migrations which occur as the developmental program of the embryo progresses. The area-code hypothesis elaborate here is an attempt to provide a framework for understanding cell-recognition phenomena in development. This hypothesis is based on extensive genetic, molecular, and cellular studies of the immune system. These studies suggest that the following events occur during the differentiation of antibody-producing cells. 1) Somatic cell lines of antibody-producing cells undergo a modification of their DNA as they become committed to synthesize a particular type of antibody molecule. This chromosomal modification event is probably a DNA translocation which leads to a somatic rearrangement of certain antibody genes. 2) In each of the specific cell lineages the new arrangement of DNA is inherited by all subsequent generations of cells. 3) The developmental programs which control these genetic alterations may be employed in a programmed and reproducible fashion. This programming of antibody development is suggested because different embryos appear to become committed to the production of identical antibody molecules in the same developmental sequence. 4) Antibody molecules are initially displayed on the cell surface where they serve as highly specifici receptors to trigger the cell to proliferate and differentiate upon interacting with appropriate external molecular signals. 5) Antibody-producing cells display combinations of different molecules on their surfaces which cause each of a very large number of different cells to interact differently with their environment. 6) The genes which code for many of these cell-surface molecules are organized into multigene families. These observations as well as information from other developmental systems have led us to propose the area-code hypothesis. This hypothesis is concerned with the structure, function, and regulation of cell-surface molecules that mediate recognition phenomena during embryogenesis. Area-code molecules are cell-surface molecules which are involved in the specific recognition phenomena during growth and development. These molecules provide cells with distinct cell-surface addresses or phenotypes, and provide the basis for the specificity in cell-cell recognition during cell migrations and cell-cell interactions, as well as serving as receptors for diffusible differentiation signals. The area-code hypothesis has 3 main postulates. i) There is a progressive display of specific combinations of area-code molecules on the surfaces of cells during development. ii) The genetic programs which determine the specific expression of area-code molecules are in part controlled by DNA modifications. These chromosomal modifications are believed to channel cells into specific lineages uith progressively restricted developmental options...

Animals↗
PubMed1977

Structure of murine Ia antigens: partial NH2-terminal amino acid sequences of products of the I-E or I-C subregion.

Partial amino acid sequence of the Ia molecule encoded by the I-E or I-C (I-EC) subregion of the major histocompatibility complex of the mouse are presented. The Ia molecule appears to be comprised of two noncovalently associated polypeptides. The larger subunit, alpha, has an approximate molecular weight of 35,000 and the smaller subunit, beta, an approximate molecular weight of 28,000. Several interesting homology relationships (or the lack thereof) are apparent when the Ia polypeptides from the I-EC subregion are compared both with their counterparts from man and guinea pig and with the molecules encoded in the I-A subregion. Clearly the most impressive homology relationship is that seen between the alpha polypeptide from the I-EC subregion of mouse and its human counterpart. This is in striking contrast to the beta polypeptide, which bears no apparent homology to its human counterpart.

Amino Acid Sequence↗