26
|
Carpenter EM, Goddard JM, Davis AP, Nguyen TP, Capecchi MR. Targeted disruption of Hoxd-10 affects mouse hindlimb development. Development 1997; 124:4505-14. [PMID: 9409668 DOI: 10.1242/dev.124.22.4505] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Targeted disruption of the Hoxd-10 gene, a 5′ member of the mouse HoxD linkage group, produces mice with hindlimb-specific defects in gait and adduction. To determine the underlying causes of this locomotor defect, mutant mice were examined for skeletal, muscular and neural abnormalities. Mutant mice exhibit alterations in the vertebral column and in the bones of the hindlimb. Sacral vertebrae beginning at the level of S2 exhibit homeotic transformations to adopt the morphology of the next most anterior vertebra. In the hindlimb, there is an anterior shift in the position of the patella, an occasional production of an anterior sesamoid bone, and an outward rotation of the lower part of the leg, all of which contribute to the defects in locomotion. No major alterations in hindlimb musculature were observed, but defects in the nervous system were evident. There was a decrease in the number of spinal segments projecting nerve fibers through the sacral plexus to innervate the musculature of the hindlimb. Deletion of a hindlimb nerve was seen in some animals, and a shift was evident in the position of the lumbar lateral motor column. These observations suggest a role for the Hoxd-10 gene in establishing regional identity within the spinal cord and imply that patterning of the spinal cord may have intrinsic components and is not completely imposed by the surrounding mesoderm.
Collapse
|
27
|
Abstract
Nitrilotriacetic acid (NTA) is extensively used in different industries because of its excellent chelating properties. Introduction of NTA into the natural environment is a concern because of mobilization of heavy metal species that may be otherwise bound to natural particulate matter. The present study investigates the adsorption behavior of Pb(II) and NTA, both as individual species and as complex species onto titanium dioxide. This adsorption information is important in considering the TiO2-assisted photocatalytic treatment of these metal-organic complexes. Pb(II) shows a typical cationic type of adsorption behavior, whereas NTA demonstrates an anionic type of adsorption trend. Results from stoichiometric ternary systems show a gradual increase in Pb(II) adsorption and a decrease in NTA removal with an increase in pH. However, for the cases of Pb(II) > NTA, increased NTA adsorption as compared to pure NTA systems was noted even at higher pH. Model predictions employing MINTEQA2 software followed the experimental trends. Experimental and model results from ternary systems suggest adsorption of free Pb(II) and NTA, as well as ternary Ti-NTA-Pb(II) and Ti-O-Pb(II)-NTA2- species. The cationic-type complexation, i.e., Ti-O-Pb(II)-NTA2-, was essential for the successful NTA adsorption modeling, especially at higher pH and for Pb > NTA systems, where significant NTA adsorption was noted even at very high pH values. Most of the previous metal-ligand adsorption studies did not consider such a surface complexation. However, the present results indicate that any groundwater transport modeling of such pollutants will require the inclusion of cationic-type surface complexation, in addition to other surface species. Copyright 1997 Academic Press. Copyright 1997Academic Press
Collapse
|
28
|
Schajer GS, Green SI, Davis AP, Hsiang YN. Influence of elastic nonlinearity on arterial anastomotic compliance. J Biomech Eng 1996; 118:445-51. [PMID: 8950647 DOI: 10.1115/1.2796030] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
This study illustrates how the highly nonlinear elastic behavior of artery wall material can cause unusual structural characteristics that do not occur with a linear-elastic material. An example mathematical model of an end-to-end anastomosis successfully predicts the experimentally observed area of elevated elastic compliance, called the "Para-anastomotic Hypercompliant Zone" (PHZ). The elastic hypercompliance is shown to occur because the anastomosis locally restricts the arterial diameter, thus forcing the adjacent material to remain in a lower strain, and correspondingly a lower stiffness, part of its non-linear stress-strain curve. Elevated elastic compliance can be avoided by locally matching both the arterial diameter and the elastic compliance within the physiological pressure range.
Collapse
|
29
|
Abstract
BACKGROUND Emergencies such as wars and natural disasters increase the vulnerability of affected populations and expose these populations to risks such as disease, violence, and hunger. Emergency public health interventions aim to mitigate these effects by providing basic minimum requirements, reducing vulnerability, and reducing exposure to risk. Targeted services are generally aimed at children under 5. Mortality rates among young children are higher than the crude mortality rate (CMR) among the whole population in emergency settings, so attention is focused on this age group. However, even under normal conditions mortality is higher in young children. This analysis compared the relative risk of death for young children with that for older children and adults under normal conditions and in emergency settings. METHODS Mortality data from refugee camps set up in response to three different emergencies were examined. Baseline mortality rates in the refugees' countries of origin were calculated from published data. Relative risks between normal and emergency conditions were calculated and compared. FINDINGS Mortality rates were higher among children under 5 than among older children and adults both under normal circumstances and in the emergency setting in camps in Tanzania, Uganda, and Zaire. However, the relative risk for under-5 versus over-5 mortality was smaller under emergency conditions than under normal circumstances. Thus, children over 5 and adults are disproportionately more affected by exposure to emergency risks than are younger children. INTERPRETATION If the objective of intervention, to reduce mortality, is to be achieved, the population over the age of 5 cannot be ignored. Emergency public health needs to develop specific tools to investigate risk in other age groups (as well as children under 5), to identify causes, and to design programmes to address such needs.
Collapse
|
30
|
Davis AP, Capecchi MR. A mutational analysis of the 5' HoxD genes: dissection of genetic interactions during limb development in the mouse. Development 1996. [PMID: 8620844 DOI: 10.1016/0168-9525(96)81460-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Using gene targeting in mice, we have undertaken a systematic mutational analysis of the homeobox-containing 5' HoxD genes. In particular, we have characterized the limb defects observed in mice with independent targeted disruptions of hoxd-12 and hoxd-13. Animals defective for hoxd-12 are viable, fertile, and appear outwardly normal yet have minor autopodal defects in the forelimb which include a reduction in the bone length of metacarpals and phalanges, and a malformation of the distal carpal bone d4. The limb phenotypes observed in hoxd-13 mutant mice are more extensive, including strong reductions in length, complete absences, or improper segmentations of many metacarpal and phalangeal bones. Additionally, the d4 carpal bone is not properly formed and often produces an extra rudimentary digit. To examine the genetic interactions between the 5' HoxD genes, we bred these mutant strains with each other and with our previously characterized hoxd-11 mouse to produce a series of trans-heterozygotes. Skeletal analyses of these mice reveal that these genes interact in the formation of the vertebrate limb, since the trans-heterozygotes display phenotypes not present in the individual heterozygotes, including more severe carpal, metacarpal and phalangeal defects. Some of these phenotypes appear to be accounted for by a delay in the ossification events in the autopod, which lead to either the failure of fusion or the elimination of cartilaginous elements. Characteristically, these mutations lead to the overall truncation of digits II and V on the forelimb. Additionally, some trans-animals show the growth of an extra postaxial digit VI, which is composed of a bony element resembling a phalange. The results demonstrate that these genes interact in the formation of the limb. In addition to the previously characterized paralogous interactions, a multitude of interactions between Hox genes is used to finely sculpt the forelimb. The 5' Hox genes could therefore act as a major permissive genetic milieu that has been exploited by evolutionary adaptation to form the tetrapod limbs.
Collapse
|
31
|
Davis AP, Capecchi MR. A mutational analysis of the 5′ HoxD genes: dissection of genetic interactions during limb development in the mouse. Development 1996; 122:1175-85. [PMID: 8620844 DOI: 10.1242/dev.122.4.1175] [Citation(s) in RCA: 179] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Using gene targeting in mice, we have undertaken a systematic mutational analysis of the homeobox-containing 5′ HoxD genes. In particular, we have characterized the limb defects observed in mice with independent targeted disruptions of hoxd-12 and hoxd-13. Animals defective for hoxd-12 are viable, fertile, and appear outwardly normal yet have minor autopodal defects in the forelimb which include a reduction in the bone length of metacarpals and phalanges, and a malformation of the distal carpal bone d4. The limb phenotypes observed in hoxd-13 mutant mice are more extensive, including strong reductions in length, complete absences, or improper segmentations of many metacarpal and phalangeal bones. Additionally, the d4 carpal bone is not properly formed and often produces an extra rudimentary digit. To examine the genetic interactions between the 5′ HoxD genes, we bred these mutant strains with each other and with our previously characterized hoxd-11 mouse to produce a series of trans-heterozygotes. Skeletal analyses of these mice reveal that these genes interact in the formation of the vertebrate limb, since the trans-heterozygotes display phenotypes not present in the individual heterozygotes, including more severe carpal, metacarpal and phalangeal defects. Some of these phenotypes appear to be accounted for by a delay in the ossification events in the autopod, which lead to either the failure of fusion or the elimination of cartilaginous elements. Characteristically, these mutations lead to the overall truncation of digits II and V on the forelimb. Additionally, some trans-animals show the growth of an extra postaxial digit VI, which is composed of a bony element resembling a phalange. The results demonstrate that these genes interact in the formation of the limb. In addition to the previously characterized paralogous interactions, a multitude of interactions between Hox genes is used to finely sculpt the forelimb. The 5′ Hox genes could therefore act as a major permissive genetic milieu that has been exploited by evolutionary adaptation to form the tetrapod limbs.
Collapse
|
32
|
Davis AP, Witte DP, Hsieh-Li HM, Potter SS, Capecchi MR. Absence of radius and ulna in mice lacking hoxa-11 and hoxd-11. Nature 1995; 375:791-5. [PMID: 7596412 DOI: 10.1038/375791a0] [Citation(s) in RCA: 477] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Mice with targeted disruptions in Hox genes have been generated to evaluate the role of the Hox complex in determining the mammalian body plan. This complex of 38 genes encodes transcription factors that specify regional information along the embryonic axes. Early in vertebrate evolution an ancestral complex shared with invertebrates was duplicated twice to give rise to the four linkage groups (Hox A, B, C and D). As a consequence, corresponding genes on the separate linkage groups, called paralogues, are most closely related to each other. Based on sequence similarities, the Hox genes have been subdivided into 13 paralogous groups. The five most 5' groups (Hox 9-13) pattern the posterior region of the vertebrate embryo and the appendicular skeleton. Mice with individual mutations in the paralogous genes hoxa-11 and hoxd-11 have been described. By breeding these two strains together we have generated double mutants which have dramatic phenotypes not apparent in mice homozygous for the individual mutations. The radius and the ulna of the forelimb are almost entirely eliminated, the axial skeleton shows homeotic transformations, and there are severe kidney defects not present in either single mutant. The limb and axial phenotypes are quantitative: as more mutant alleles are added to the genotype, the phenotype becomes progressively more severe. The appendicular skeleton defects suggest that paralogous Hox genes function together to specify limb outgrowth and patterning along the proximodistal axis.
Collapse
|
33
|
Davis AP, Capecchi MR. Axial homeosis and appendicular skeleton defects in mice with a targeted disruption of hoxd-11. Development 1994; 120:2187-98. [PMID: 7925020 DOI: 10.1242/dev.120.8.2187] [Citation(s) in RCA: 185] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Using gene targeting, we have created mice with a disruption in the homeobox-containing gene hoxd-11. Homozygous mutants are viable and the only outwardly apparent abnormality is male infertility. Skeletons of mutant mice show a homeotic transformation that repatterns the sacrum such that each vertebra adopts the structure of the next most anterior vertebra. Defects are also seen in the bones of the limb, including regional malformations at the distal end of the forelimb affecting the length and structure of phalanges and metacarpals, inappropriate fusions between wrist bones, and defects at the most distal end in the long bones of the radius and ulna. The phenotypes show both incomplete penetrance and variable expressivity. In contrast to the defects observed in the vertebral column, the phenotypes in the appendicular skeleton do not resemble homeotic transformations, but rather regional malformations in the shapes, length and segmentation of bones. Our results are discussed in the context of two other recent gene targeting studies involving the paralogous gene hoxa-11 and another member of the Hox D locus, hoxd-13. The position of these limb deformities reflects the temporal and structural colinearity of the Hox genes, such that inactivation of 3′ genes has a more proximal phenotypic boundary (affecting both the zeugopod and autopod of the limb) than that of the more 5′ genes (affecting only the autopod). Taken together, these observations suggest an important role for Hox genes in controlling localized growth of those cells that contribute to forming the appendicular skeleton.
Collapse
|
34
|
Boyle PH, Borchert M, Davis AP, Heaney FM, Ziegler I. Modulation of interleukin 2 high affinity binding to human T cells by a pyrimidodiazepine insect metabolite. FEBS Lett 1993; 334:309-12. [PMID: 8243638 DOI: 10.1016/0014-5793(93)80700-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
An insect metabolite containing the little known pyrimido[4,5-b][1,4]diazepine ring system has been found to act as an effective mimic of tetrahydrobiopterin in its ability to modulate the affinity of interleukin 2 (IL-2) for its receptors on human T cells. Semi-empirical molecular orbital calculations reveal that while tetrahydrobiopterin has considerable flexibility, the pyrimidodiazepine has rather few conformational options and offers a useful model for exploring the nature of the pterin binding site.
Collapse
|
35
|
Roopenian DC, Davis AP, Christianson GJ, Mobraaten LE. The functional basis of minor histocompatibility loci. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 1993; 151:4595-605. [PMID: 8409421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
This work addresses the functional basis of classical minor histocompatibility (H) loci. We focus on the H-3 locus, which is actually a complex genetic unit to which the phenotypic trait of tissue rejection, genes whose products stimulate specific subsets of T cells, and Ir genes have been mapped. To clarify how these genes relate to one another and to the trait of tissue rejection, strains of intra-H-3 recombinant mice were produced and analyzed. These mice allowed us to selectively elicit immune responses to Ag (referred to as type I Ag) that stimulate MHC class I-restricted CTL, or Ag (referred to as type II Ag) that stimulate MHC class II-restricted Th. The splitting of H-3 in this manner resulted in a dramatic diminution of the skin allograft response, and with rare exception, an elimination of the CTL response after spleen cell immunization. A selective response to type I Ag resulted in slow, incomplete skin allograft rejection that demonstrated both CD4+ cell-dependent and -independent components. A selective response to the type II Ag failed to result in allograft rejection. The type II Ag did, however, act as an Ir gene that determined whether responses to type I Ag could occur. Altogether, the results indicate that the trait of tissue rejection associated with H-3 is a consequence of the strongly synergistic effects of Th-CTL collaboration induced by products of type I and type II genes. Moreover, the results suggest a genetic explanation for some of the Ir gene effects associated with H-3.
Collapse
|
36
|
Roopenian DC, Davis AP, Christianson GJ, Mobraaten LE. The functional basis of minor histocompatibility loci. THE JOURNAL OF IMMUNOLOGY 1993. [DOI: 10.4049/jimmunol.151.9.4595] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
This work addresses the functional basis of classical minor histocompatibility (H) loci. We focus on the H-3 locus, which is actually a complex genetic unit to which the phenotypic trait of tissue rejection, genes whose products stimulate specific subsets of T cells, and Ir genes have been mapped. To clarify how these genes relate to one another and to the trait of tissue rejection, strains of intra-H-3 recombinant mice were produced and analyzed. These mice allowed us to selectively elicit immune responses to Ag (referred to as type I Ag) that stimulate MHC class I-restricted CTL, or Ag (referred to as type II Ag) that stimulate MHC class II-restricted Th. The splitting of H-3 in this manner resulted in a dramatic diminution of the skin allograft response, and with rare exception, an elimination of the CTL response after spleen cell immunization. A selective response to type I Ag resulted in slow, incomplete skin allograft rejection that demonstrated both CD4+ cell-dependent and -independent components. A selective response to the type II Ag failed to result in allograft rejection. The type II Ag did, however, act as an Ir gene that determined whether responses to type I Ag could occur. Altogether, the results indicate that the trait of tissue rejection associated with H-3 is a consequence of the strongly synergistic effects of Th-CTL collaboration induced by products of type I and type II genes. Moreover, the results suggest a genetic explanation for some of the Ir gene effects associated with H-3.
Collapse
|
37
|
Moxley RA, Olson LD, Davis AP. Experience with a planned exposure program for the control of enzootic transmissible gastroenteritis in swine. J Am Vet Med Assoc 1993; 202:1861-4. [PMID: 8391524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Oral inoculation of pregnant sows and gilts with a homogenate of pig intestines containing live, virulent transmissible gastroenteritis (TGE) virus was associated with significant (P < 0.01) reduction of mortality in nursery pigs in a herd affected with enzootic TGE. The mortality of weaned pigs from April through June 1981, when sows were not vaccinated or inoculated, was 9.3%. Mortality of weanling pigs from July through December 1981 was 5.7% (P < 0.01), and stayed consistently between 2.6 and 4.8% from 1982 through 1990. After beginning the exposure program, there were no clinical signs attributable to TGE in the farrowing house or nursery until 1986, when recrudescence of TGE was evident in the nursery. Although the source of the virus could not be substantiated, recrudescence suggested that TGE virus would not be eradicated as long as exposure was continued. The most plausible explanation for the decrease in the incidence of diarrhea and mortality in the nursery pigs after initiation of the planned exposure program is that a higher, longer lasting amount of lactogenic immunity was provided to suckling pigs. Presumably over time, this resulted in less TGE virus carryover into the nursery by weanling pigs, thereby reducing and confining the environmental challenge to the nursery. Strict all-in, all-out pig movement in the nursery with thorough cleaning and disinfecting presumably further reduced the environmental challenge.
Collapse
MESH Headings
- Administration, Oral
- Animals
- Disease Outbreaks/veterinary
- Female
- Gastroenteritis, Transmissible, of Swine/epidemiology
- Gastroenteritis, Transmissible, of Swine/mortality
- Gastroenteritis, Transmissible, of Swine/prevention & control
- Immunity, Maternally-Acquired
- Incidence
- Injections, Intramuscular/veterinary
- Pregnancy
- Swine
- Transmissible gastroenteritis virus/immunology
- Vaccination/veterinary
- Vaccines, Attenuated/administration & dosage
- Viral Vaccines/administration & dosage
- Weaning
Collapse
|
38
|
Roopenian DC, Christianson GJ, Davis AP, Zuberi AR, Mobraaten LE. The genetic origin of minor histocompatibility antigens. Immunogenetics 1993; 38:131-40. [PMID: 7683307 DOI: 10.1007/bf00190900] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The purpose of this study was to elucidate the genetic origin of minor histocompatibility (H) antigens. Toward this end common inbred mouse strains, distinct subspecies, and species of the subgenus Mus were examined for expression of various minor H antigens. These antigens were encoded by the classical minor H loci H-3 and H-4 or by newly identified minor H antigens detected as a consequence of mutation. Both minor H antigens that stimulate MHC class I-restricted cytotoxic T cells (Tc) and antigens that stimulate MHC class II-restricted helper T cells (Th) were monitored. The results suggested that strains of distinct ancestry commonly express identical or cross-reactive antigens. Moreover, a correlation between the lack of expression of minor H antigens and ancestral heritage was observed. To address whether the antigens found on unrelated strains were allelic with the sensitizing minor H antigens or a consequence of antigen cross-reactivity, classical genetic segregation analysis was carried out. Even in distinct subspecies and species, the minor H antigens always mapped to the site of the appropriate minor H locus. Together the results suggest: 1) minor H antigen sequences are evolutionarily stable in that their pace of antigenic change is slow enough to predate subspeciation and speciation; 2) the minor H antigens originated in the inbred strains as a consequence of a rare polymorphism or loss mutation carried in a founder mouse stock that caused the mouse to perceive the wild-type protein as foreign; 3) there is a remarkable lack of antigenic cross-reactivity between the defined minor H antigens and other gene products.
Collapse
|
39
|
Ziegler I, Borchert M, Heaney F, Davis AP, Boyle PH. Structural requirements for the modulatory effect of 6-substituted pterins on interleukin 2 receptor binding. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1135:330-4. [PMID: 1535794 DOI: 10.1016/0167-4889(92)90239-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
(6R)-5,6,7,8-Tetrahydrobiopterin is produced by stimulated human T lymphocytes, and is known to affect various aspects of interleukin-2-directed T cell proliferation. Using an increased apparent affinity of interleukin 2 receptor to interleukin 2 as a measure of activity, this study explores whether other 6-substituted pterins might have the same effect, and what structural features are necessary for activity. Of the compounds tested, only the T-lymphocyte-derived (6R)-5,6,7,8-tetrahydrobiopterin was active. The diastereomeric (6S)-5,6,7,8-tetrahydrobiopterin was inactive, as were 7,8-dihydrobiopterin, sepiapterin, 5,6,7,8-tetrahydroneopterin, 6,7-dimethyl-5,6,7,8-tetrahydropterin and 6-hydroxymethylpterin. 7,8-Dihydroneopterin and neopterin were also found to be inactive. It follows that neither of these compounds participates in the feedback modulation of IL-2 receptor affinity, although both of them can be detected upon IFN-gamma stimulation of human monocytes/macrophages. A computer-based molecular modelling study of (6R)-5,6,7,8-tetrahydrobiopterin and (6R)-5,6,7,8-tetrahydroneopterin revealed substantial differences in overall shape between the two molecules, with certain features figuring prominently in the low-energy conformers of (6R)-5,6,7,8-tetrahydrobiopterin.
Collapse
|
40
|
Abstract
The fine immunogenetics of the chromosome 7 mouse minor histocompatibility (H) locus H-4 was investigated. Both class I major histocompatibility complex (MHC)-restricted cytotoxic T lymphocytes (CTL) and class II MHC-restricted "helper" T cells (TH) specifically reactive with H-4 antigens were isolated as clones and were used as genetic probes for classical backcross segregation analysis. Results of a four point cross indicated that the H-4 locus was actually comprised of two genes, that have been designated H-46 and H-47. The former encodes antigens recognized by the TH and the latter encodes antigens recognized by the CTL. Moreover, these two genes could be separated from the gene pink-eyed dilution (p) which was found to be "sandwiched" between them. The functional significance of a minor H congenic strain differing by both TH-defined H-46 and CTL-defined H-47 was addressed using F1 complementation tests. Such studies indicated that immune responses against H-46 antigens was required for generation of H-47-specific CTL. Altogether, these results suggest selective presentation of different minor H gene products by class I or class II MHC proteins and that the minor H "locus" H-4 may have necessarily included both TH and CTL-defined genes because of requisite TH-CTL collaboration.
Collapse
|
41
|
Roopenian DC, Davis AP. Responses against antigens encoded by the H-3 histocompatibility locus: antigens stimulating class I MHC- and class II MHC-restricted T cells are encoded by separate genes. Immunogenetics 1989; 30:335-43. [PMID: 2530167 DOI: 10.1007/bf02425273] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The purpose of this work was to study the genetic basis of histocompatibility antigens encoded by the mouse minor histocompatibility (H) locus H-3. Both class I major histocompatibility complex (MHC)-restricted cytotoxic T lymphocytes (CTL) and class II MHC-restricted helper T cells (TH) specific for antigens encoded by genes within the H-3 locus were isolated and analyzed. Typing a number of mouse strains for expression of antigens recognized by these TH and CTL suggested that there was a different strain distribution pattern of expression of the antigens recognized by TH compared with those recognized by CTL. Separation of the genes whose products stimulate TH from those whose products stimulate CTL was suggested by: (1) analysis of the strain B10.FS(92NX)/Grf that has undergone recombination within the H-3 region; (2) genetic segregation studies of (B10.UW-H-3b/Sn x C57BL/10Sn)F2 mice; and (3) F1 complementation studies in which CTL specific for products of the TH-defined gene(s) could not be detected, even in the absence of immune responses to products of the CTL-defined genes. Taken together, these data suggest that in addition to two genes (B2m and Cd-1) within the H-3 region whose products typically stimulate class I MHC-restricted CTL, there is at least one additional gene whose product selectively stimulates class II MHC-restricted TH. This new gene is located telomeric from the CTL-defined genes and between the loci we and un on chromosome 2. These data demonstrate a novel degree of complexity of the H-3 "locus" and suggest selective presentation of minor H gene products in the context of class I or class II MHC proteins.
Collapse
|
42
|
Davis AP, Graham JK, Foote RH. Homospermic versus heterospermic insemination of zona-free hamster eggs to assess fertility of fluorochrome-labeled acrosome-reacted bull spermatozoa. GAMETE RESEARCH 1987; 17:343-54. [PMID: 3507357 DOI: 10.1002/mrd.1120170407] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Fresh spermatozoa from six bulls, with fertility ranging from 64% to 78%, (based upon 59-day nonreturn rates for 159,448 cows inseminated) were mixed with zona-free hamster eggs in 15 heterospermic pair inseminations. Five of the bulls were used in homospermic insemination studies. Prior to incubation, spermatozoa from each bull were labeled with contrasting fluorescent stains pretested for effects on spermatozoa. Equal numbers of spermatozoa were mixed and treated with liposomes of dilauroylphosphatidylcholine to induce the acrosome reaction. Spermatozoa from split ejaculates within a male competed against each other equally in the hamster egg test, indicating that the staining procedure did not affect egg penetration rates. Bulls differed in their egg penetration rates when their sperm were inseminated either homospermically or heterospermically, but the differences in the homospermic inseminations were not significantly correlated with sire fertility. The number and percentage of sperm which penetrated eggs, and the number of eggs penetrated in the heterospermic competitive tests were highly correlated with fertility (r greater than or equal to 0.86). Therefore, egg penetration rates from heterospermic inseminations appear to be valuable indicators of fertility and much more sensitive predictors than results from homospermic inseminations.
Collapse
|
43
|
Davis AP, Foote RH. Relationship of sire fertility to acrosome-reacted and motile spermatozoa after treatment with liposomes. J Dairy Sci 1987; 70:850-7. [PMID: 3584619 DOI: 10.3168/jds.s0022-0302(87)80083-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The relationship between bull non-return rate and percent acrosome-reacted and percent motile sperm treated with 24.8, 34.8, and 44.8 microM dilauroylphosphatidylcholine liposomes was examined. Frozen-thawed spermatozoa from six bulls, with fertility ranging from 64 to 78%, were incubated at 39 degrees C with the liposomes for 0, 7, and 15 min. Bulls differed in percentages of motile sperm, and this decreased over time, especially at the highest concentration of lipids (44.8 microM). Bulls differed initially in their percentage of sperm with intact acrosomes and in their linear rate of increase in percent acrosome-reacted sperm. At 24.8 microM of lipid the rate of increase was nearly linear, whereas at higher concentrations the maximum acrosome reaction was approached during short incubations. The variables 1) decline in percent motile sperm and 2) increase in percent acrosome-reacted sperm, used singly, predicted fertility most accurately when measured on sperm treated with 44.8 and 24.8 microM of lipids, respectively. However, the highest relationship (R2 greater than or equal to .97) was established by combining the acrosome and motility measurements of sperm exposed to 34.8 microM of lipids. Thus, potential fertility of bulls may be predicted by application of this assay to frozen-thawed semen.
Collapse
|
44
|
Rather PN, Davis AP, Wilkinson BJ. Slime production by bovine milk Staphylococcus aureus and identification of coagulase-negative staphylococcal isolates. J Clin Microbiol 1986; 23:858-62. [PMID: 3711274 PMCID: PMC268737 DOI: 10.1128/jcm.23.5.858-862.1986] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Staphylococcus aureus isolates from bovine milk were assessed for capsule or slime production. When pure S. aureus cultures in milk were inoculated directly into serum-soft agar constituted with a modified staphylococcus 110 medium, 100% of the isolates grew with diffuse colony morphology. Diffuse colony morphology was rapidly lost on subculture and was more rapidly lost in brain heart infusion-serum-soft agar. No evidence was seen for encapsulation in India ink preparations or by the clumping factor test. It was concluded that freshly isolated S. aureus strains produce slime, not true capsules. During examination of the 84 milk samples that grew staphylococci in addition to S. aureus (27.4%), a significant number of coagulase-negative staphylococcal species were encountered and identified by conventional tests as S. simulans (41.7%), S. xylosus (11.9%), S. epidermidis (3.6%), S. saprophyticus (3.6%), S. hyicus (2.9%), S. cohnii (1.2%), S. haemolyticus (1.2%), and S. warneri (1.2%). Five isolates (6.0%) were not identified. Attempts were also made to identify the isolates by the API Staph-Ident system, which gave an overall accuracy of 45.2%. The susceptibilities of the isolates to a variety of antibiotics were determined, and they appeared to be less resistant than human clinical isolates.
Collapse
|
45
|
Davis AP. Project HITE (health individualization and teacher education): a health curriculum for 3-, 4- and 5-year olds. THE JOURNAL OF SCHOOL HEALTH 1983; 53:433-434. [PMID: 6556396 DOI: 10.1111/j.1746-1561.1983.tb03156.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
South Carolina has been a national leader in such health problems as cardiovascular disease, syphillis and gonorrhea. Since many of the problems could be attributed to poor health habits, education of the state's residents seemed in order. The education/re-education of inaccessible adults with firmly established health habits--poor or otherwise--was not feasible, but the education of impressionable, readily accessible three-, four- and five-year olds was possible. Through a grant from the federal government, an individualized health curriculum that could accommodate the differences of the learners and include vital health content was developed. This project of developing and distributing the health curriculum to teachers of young children was called Project HITE (Health Individualization and Teacher Education).
Collapse
|
46
|
Davis AP, Gropper L, Shimkin MB. Response of Wistar rats with breast cancer induced by 3-methylcholanthrene to thirty-one compounds. Cancer Res 1966; 26:19-33. [PMID: 5910922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
|
47
|
Davis AP, Gruenstein M, Shimkin MB. Evaluation of chemotherapeutic agents in mammary carcinoma induced by 3-methylcholanthrene in Wistar rats. Cancer Res 1966; 26:1-18. [PMID: 5212551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
|
48
|
Davis AP. President's Column. J Natl Med Assoc 1954; 46:198. [PMID: 20893700 PMCID: PMC2617455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
|
49
|
Davis AP. President's Column. J Natl Med Assoc 1954; 46:133-134. [PMID: 20893693 PMCID: PMC2617356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
|
50
|
Davis AP. President's Column. J Natl Med Assoc 1954; 46:67. [PMID: 20893686 PMCID: PMC2617423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
|