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Biomedical subjects

A J Nelson

Publications and source records attributed to A J Nelson.

At least 37 records · Page 2Linked to original sources
PubMed1996

Head and neck pain review: traditional and new perspectives.

A variety of conditions are frequently associated with the occurrence of head and neck pain. The purposes of this review are: to describe the characteristics of several musculoskeletal, neurological, and systemic conditions frequently cited as possible causes of head and neck pain and to suggest a new technique for treating head and neck pain. The characteristics of musculoskeletal conditions, such as muscle spasm, tendinitis, trigger points, and joint inflammation, and their relationship to head and neck pain are considered. The features and clinical implications of neurologic conditions, such as atypical facial pain, trigeminal and glossopharyngeal neuralgia, reflex sympathetic dystrophy, and neurogenic inflammation, are also described. The distinguishing characteristics of headaches, including cluster, tension, chronic daily, rebound, posttraumatic, and postlumbar puncture, are detailed. This review also addresses the contributions of systemic disorders, such as osteoarthritis, rheumatoid arthritis and the variants, and rheumatoid-related conditions, like dermatomyositis, temporal arteritis, Lyme's disease, and fibromyalgia, to head and neck pain. The results of a recent pilot study of the effectiveness of intraoral circulating ice water for resolving symptoms related to head and neck pain secondary to neurogenic inflammation are presented in this work. Ice water circulating through hollow metal tubes was placed intraorally for 15 minutes in the posterior maxillary area on 12 individuals with cervical pain and muscle spasm. In nine of these individuals, reduced cervical pain perception, upper trapezius electromyography signal reduction, and increased cervical range of motion was produced. Six out of 12 individuals had accompanying headache, which was reduced or eliminated in four cases. These findings suggest a strong trigemino-cervical relationship to neck pain and headache.

Headache↗
PubMed1994

Expression of two structurally identical viral superantigens results in thymic elimination at distinct developmental stages.

Mouse mammary tumor virus proviral integrants encode superantigens. Developing thymocytes bearing TCRs with particular V beta elements encounter these endogenous viral superantigens as self molecules in the thymus and are consequently clonally eliminated. To study this mechanism of tolerance induction, we have bred B10.BR-Mtv-1 and B10.BR-Mtv-6 mice, which carry either Mtv-1 or Mtv-6 proviruses but are otherwise genetically identical. The protein products of these mouse mammary tumor virus integrants, vSAG1 and vSAG6, both interact with V beta 3+ T cells and have identical amino acid sequences. Interestingly, vSAG6 expression results in the complete deletion of V beta 3+ peripheral T cells, whereas vSAG1 expression results in only partial deletion. Flow cytometric analyses indicate that B10.BR-Mtv-6 mice delete V beta 3+ thymocytes at the immature CD4+8+ stage, whereas B10.BR-Mtv-1 mice delete only mature CD4+ or CD8+ cells. In addition, the two strains exhibit different time courses of thymic deletion: neonatal B10.BR-Mtv-6 mice eliminate V beta 3+ T cells by day 2, in contrast to B10.BR-Mtv-1 mice in which deletion does not occur until day 15. RNase protection assays demonstrate that B10.BR-Mtv-6 mice have significantly greater thymic vSAG6 mRNA expression levels than vSAG1 levels in B10.BR-Mtv-1 animals, correlating with a more complete deletion of reactive thymocytes at an earlier point in the maturational sequence.

Animals↗
PubMed1994

Characterization of a CD6 ligand(s) expressed on human- and murine-derived cell lines and murine lymphoid tissues.

CD6, a type I cell surface glycoprotein expressed predominantly by thymocytes and mature T lymphocytes, becomes phosphorylated on tyrosine residues following T cell activation and has been implicated as an accessory molecule in T cell activation. The purpose of this study was to identify cell lines and tissues which express CD6 ligand(s), determine the requirements for CD6 binding, and biochemically characterize the putative CD6 ligand(s). Binding studies with a CD6 immunoglobulin fusion protein, CD6-Rg, allowed the identification of a number of human cell lines which express a CD6 ligand(s). The binding to these cell lines was trypsin sensitive, in part required divalent cations, was blocked by an anti-CD6 mAb, and could be downregulated by tumor necrosis factor alpha (TNF alpha), interleukin-1 beta (IL-1 beta) and interferon-gamma (IFN-gamma). Among the cell lines tested, the human breast carcinoma-derived cell line HBL-100 expressed the highest levels of CD6 ligand(s) and was used for immunoprecipitation studies. Following metabolic labeling, CD6-Rg immunoprecipitated glycoproteins of approximately 100, approximately 90, and approximately 45 kDa from HBL-100 cells. Using CD6-Rg we were able to show that murine thymus, lymph nodes, and skin express high levels of CD6 ligand(s) and that CD6-Rg bound to a murine thymic epithelial cell line and to cultured human epidermal keratinocytes.

Animals↗
PubMed1994

Isolation of a monocot 3-hydroxy-3-methylglutaryl coenzyme A reductase gene that is elicitor-inducible.

The rice (Oryza sativa) phytoalexins, momilactones and oryzalexins, are synthesized by the isoprenoid pathway. An early step in this pathway, one that is rate-limiting in mammalian systems, is catalyzed by the enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR). A gene that encodes this enzyme has been isolated from rice, and found to contain an open reading frame of 1527 bases. The encoded protein sequence of the rice HMGR appears to be conserved with respect to other HMGR proteins, and 1 or 2 membrane-spanning domains characteristic of plant HMGRs are predicted by a hydropathy plot of the amino acid sequence. The protein is truncated at its 5' end, and shows reduced sequence conservation in this region as compared to other plant sequences. The rice genome contains a small family of HMGR genes. The isolated gene, HMGR I, is expressed at low levels in both vegetative and floral organs of rice plants. It is not induced in plants by wounding, but is strongly and rapidly induced in suspension cells by a fungal cell wall elicitor from the pathogen Magnaporthe grisea, causal agent of rice blast disease. This suggests that HMGR I may be important in the induction of rice phytoalexin biosynthesis in response to pathogen attack, and therefore may play a key role as a component of the inducible defense mechanism in rice.

Amino Acid Sequence↗
PubMed1994

Information needs of the dairy industry for health and nutrition management.

Current DHI records usage is demonstrated with lactation curves, peak milk production versus rolling average peak milk production, and linear score monitoring sensitivity. Suggestions for the future of DHI records include national congruity, reduction in DHI fees, increased use of electronic transfer of information, increased availability of records from all testing centers, decreased use of DHI supervisors, milk urea nitrogen testing, and tracking of metabolic diseases.

Animal Nutritional Physiological Phenomena↗
PubMed1993

Medullary thymic epithelium expresses a ligand for CTLA4 in situ and in vitro.

A fusion protein consisting of the extracellular domain of CTLA4 and an Ig C gamma 1 chain (CTLA4-Ig) was used to examine the distribution of the ligands for CTLA4 within the murine thymus and to characterize the nature of these ligands. Two-color immunofluorescence of thymus tissue revealed binding of the fusion protein to medullary thymic epithelial cells and dendritic cells within the corticomedullary and medullary areas of the thymus. Medullary cells binding the fusion protein also expressed MHC class II products and ICAM-1. Thymus tissue sections treated with cross-linking fixatives, such as glutaraldehyde, paraformaldehyde, or 1-ethyl-3(3-dimethylaminopropyl)-carbodiimide no longer bound the CTLA4 fusion protein, indicating that binding was very sensitive to the tertiary structure of the tissue ligand. The ability of thymic tissue to bind the fusion protein was developmentally regulated. At day 14 of gestation, only scattered single cells were labeled. Clusters of labeled cells, which were detected by day 16 of gestation, increased in frequency with advancing gestational age. Consistent with the in situ labeling studies, CTLA4-Ig also labeled several thymic epithelial cell lines previously shown to have a medullary phenotype. Polymerase chain reaction analysis of mRNA extracted from these cells indicated they contained mRNA for B7, a known counter receptor for CTLA4 and CD28. Immunoprecipitation of 125I-labeled thymic epithelial cells with the CTLA4-Ig detected a M(r) 65,000 to 70,000 species under reducing conditions, consistent with previous studies of B7. These data suggest that the ligand for CTLA4 expressed by thymic epithelial cells in vitro is B7 and that the expression of this ligand in situ is largely restricted to the medullary compartment and is associated with epithelial cells and dendritic cells.

Abatacept↗
PubMed1992

Characterization and cloning of a novel glycoprotein expressed by stromal cells in T-dependent areas of peripheral lymphoid tissues.

A novel glycoprotein (gp) expressed by stromal cells of peripheral lymphoid tissue has been characterized immunohistochemically, biochemically, and at the molecular level. This molecule, gp38, was identified with a monoclonal antibody (mAb) (clone 8.1.1) previously shown to react with a subpopulation of thymic epithelium. This mAb generated a reticular labeling pattern in medullary and paracortical areas of lymph nodes and in splenic white pulp. At the ultrastructural level, labeling by the 8.1.1 mAb was restricted to fibroblastic reticular stromal cells. Serial sections of lymph node and spleen labeled with anti-CD3, anti-B220, and 8.1.1 mAbs clearly showed that the 8.1.1+ cells were associated with T cell-dependent areas. In severe combined immunodeficiency (SCID) or Nu/Nu mice, splenic white pulp also exhibited reticular labeling with the 8.1.1 mAb in the absence of detectable numbers of T cells, indicating that the appearance of 8.1.1-reactive stromal cells in discrete areas of peripheral lymphoid tissue was T cell independent. The cDNA encoding this stromal cell molecule was cloned by direct expression in COS cells and found to encode a 172 amino acid sequence with the typical features of a type I integral membrane protein. COS cells transfected with the gp38 clone direct the expression of an approximately 38-kD protein that reacts with the 8.1.1 mAb but not with isotype-matched controls. Comparison of the predicted amino acid sequence of 8.1.1 mAb but not with isotype-matched controls. Comparison of the predicted amino acid sequence of 8.1.1 with proteins in the National Biomedical Research Foundation (NBRF) data base showed that gp38 is very closely related to the early response protein OTS-8 obtained from a cDNA library of tumor promoting agent (TPA)-induced murine osteoblastic cell line, MC3T3-E1.

Amino Acid Sequence↗
PubMed1989

The key role of records in a production medicine practice.

The needs of dairy farmers for veterinary assistance have changed and are still changing. It appears that many future opportunities in dairy practice will involve active consultation on herd management factors. The ability to evaluate herd records will be crucial to this effort. This article discusses organizing and then utilizing a production medicine program based on systematic records analysis.

Animals↗
PubMed1988

Hyperthermia.

Explore the source record for details and available documents.

Humans↗
PubMed1988

Antihypertensive thiadiazoles. 1. Synthesis of some 2-aryl-5-hydrazino-1,3,4-thiadiazoles with vasodilator activity.

Some 2-aryl-5-hydrazino-1,3,4-thiadiazoles have been synthesized and screened for antihypertensive activity. In general, compounds with a 2-substituted phenyl ring had higher activity than their 3- or 4-substituted counterparts or those containing heteroaryl groups. The 2-methylphenyl and 2-ethylphenyl derivatives 7 and 18 were the most potent members of the series. Preliminary studies indicated that the hypotensive action of these compounds was due to a direct relaxant effect on vascular smooth muscle.

Animals↗
PubMed1988

Antihypertensive thiadiazoles. 2. Vasodilator activity of some 2-aryl-5-guanidino-1,3,4-thiadiazoles.

Some 2-aryl-5-guanidino-(or N-substituted guanidino)-1,3,4-thiadiazoles and closely related analogues were found to lower blood pressure in metacorticoid (DOCA) hypertensive rats. In the unsubstituted guanidines that exhibited low toxicity, optimum activity resulted when the aryl group was a 2-methylphenyl ring (11). Modifications to the guanidine group did not increase antihypertensive activity, but, in the 2-methylphenyl series, the N-n-butyl- and N-(2-methoxyethyl)guanidines (63 and 78) and the related iminoimidazolidine 93 were of comparable activity to that of the unsubstituted guanidine 11. The iminoimidazolidine 93 showed a somewhat longer duration of action than the guanidine derivatives. Preliminary studies in a pithed rat preparation indicated that these thiadiazole derivatives (11, 63, and 93) lowered blood pressure by a direct relaxant effect on vascular smooth muscle.

Animals↗
PubMed1988

The effect of early functional activities on experimentally tenotomized Achilles tendons in rats.

Muscle atrophy, joint stiffness, osteoarthritis, infection, skin necrosis, atrophy and ulceration of joint cartilage and tendocutaneous adhesion are familiar complications produced by prolonged immobilization of surgically repaired tendon ruptures. Because these complications may be minimized by limited immobilization and early functional activities, we studied the effects of early weight bearing on the maximum breaking strength of tenotomized tendons in 30 Wistar rats. After tenotomy, the right hind limb of the first group of 10 rats was immobilized for the first 5 days. Thereafter their casts were removed to permit weight bearing for the next 3 days. In a second group of 10 rats, casts were removed 2 days after surgery, the animals were allowed 3 days of unrestricted use of the limb, and then the limbs were re-casted for another 3 days. In a third group of 10 rats the right hind limbs were casted throughout the first 8 days of healing. At the end of this time, strain gauge measurements showed that tendons in the second group healed significantly stronger and without rerupture than those in either of the two groups. Although healing time in rats does not directly translate to humans, our findings suggest that function may return faster in humans, as, for example, following Achilles tendon rupture, if a better combination of immobilization and activity could be found than is currently employed.

Achilles Tendon↗
PubMed1987

Low-intensity pulsed galvanic current and the healing of tenotomized rat achilles tendons: preliminary report using load-to-breaking measurements.

The possible beneficial effects of low-intensity, pulsed galvanic currents on the healing of tenotomized Achilles tendons was investigated in three groups (20 animals each) of male Sprague-Dawley rats. Treatments via implanted electrodes were given once daily for 15 minutes over a two-week period. Although a portable high-voltage galvanic stimulator was used, stimulus intensity was only 75 microA at a frequency of 10/sec. Tendons were tested after two weeks for the load required to rebreak them at the original tenotomy site. The group treated with anodal current withstood significantly greater loads (p less than 0.001) than did either the group which healed normally (ie, without stimulation) or the group treated with cathodal current.

Achilles Tendon↗
PubMed1986

Analysis of growth patterns during gravitropic curvature in roots of Zea mays by use of a computer-based video digitizer.

A computer-based video digitizer system is described which allows automated tracking of markers placed on a plant surface. The system uses customized software to calculate relative growth rates at selected positions along the plant surface and to determine rates of gravitropic curvature based on the changing pattern of distribution of the surface markers. The system was used to study the time course of gravitropic curvature and changes in relative growth rate along the upper and lower surface of horizontally-oriented roots of maize (Zea mays L.). The growing region of the root was found to extend from about 1 mm behind the tip to approximately 6 mm behind the tip. In vertically-oriented roots the relative growth rate was maximal at about 2.5 mm behind the tip and declined smoothly on either side of the maximum. Curvature was initiated approximately 30 min after horizontal orientation with maximal (50 degrees) curvature being attained in 3 h. Analysis of surface extension patterns during the response indicated that curvature results from a reduction in growth rate along both the upper and lower surfaces with stronger reduction along the lower surface.

Computer Systems↗