Congenital stationary night blindness in briards in the UK.
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Animals↗
Biomedical subjects
N Holmes
Publications and source records attributed to N Holmes.
Fetal surgery for posterior urethral valves: long-term postnatal outcomes.
OBJECTIVE: Fetal intervention for obstructive uropathy was first performed at the University of California, San Francisco in 1981. Indications for treatment were bilateral hydronephrosis with oligohydramnios. Preintervention criteria included fetal urinary electrolytes with beta-microglobulin levels, karyotyping, and detailed sonography specifically looking for renal cortical cysts. We reviewed the outcomes of children who underwent fetal intervention with specific long-term follow-up in patients who were found postnatally to have posterior urethral valves. METHODS: A retrospective review of the University of California, San Francisco fetal surgery database was performed for patients with a prenatal diagnosis of obstructive uropathy. Medical records from 1981 to 1999 were reviewed. Long-term follow-up was documented if the cause of the urinary tract obstruction was posterior urethral valves. We collected data points, focusing on time and type of intervention, fetal urinary electrolytes, appearance of fetal kidneys, present renal function, length of follow-up, and present status of the urinary tract. RESULTS: Forty patients were evaluated for fetal intervention; 36 fetuses underwent surgery during this time period. Postnatal confirmation of posterior urethral valves was demonstrated in 14 patients. All patients had favorable fetal urinary electrolytes. Mean gestational age at intervention was 22.5 weeks. The procedures performed included creation of cutaneous ureterostomies in 1, fetal bladder marsupialization in 2, in utero ablation of valves in 2, and placement of vesicoamniotic catheter in 9. Six deaths occurred before term delivery with premature labor and the newborns succumbing to respiratory failure. One pregnancy was terminated electively because of shunt failure and declining appearance of fetal lungs and kidney. The remaining 8 living patients had a mean follow-up of 11.6 years. Chronic renal disease with abnormal serum creatinine was present in 5 patients. Two patients have undergone renal transplantation, and 1 is awaiting organ donation. Five of the 8 living patients have had urinary diversion with vesicostomy, cutaneous ureterostomy, or augmentation cystoplasty with later reconstruction. CONCLUSIONS: Fetal intervention for posterior urethral valves carries a considerable risk to the fetus with fetal mortality rate of 43%. The long-term outcomes indicate that intervention may not change the prognosis of renal function or be a predictor for possible urinary diversion. Despite all of these patients' having favorable urinary electrolytes, this did not seem to have any implication postnatally. When counseling families about fetal intervention, efforts should be focused on that intervention may assist in delivering the fetus to term and that the sequelae of posterior urethral valves may not be preventable. Fetal surgery for obstructive uropathy should be performed only for the carefully selected patient who has severe oligohydramnios and "normal"-appearing kidneys.
Adolescent↗
Acute myocardial infarction and the 12-lead ECG.
It is important that critical care nurses are able to identify the location of cardiac muscle ischemia, injury, and infarction on the electrocardiogram. Knowing the site of infarction is essential in anticipating clinical manifestations and, therefore, has implications for the patient's plan of care. This article includes an overview of four sites of infarction: inferior, posterior, anterior, and lateral. The coronary artery source of each, as well as the ECG findings and clinical signs and symptoms are discussed.
Electrocardiography↗
Changes in skills for people with intellectual disability: a follow-up of the Camberwell Cohort.
The skills of a total population of children with severe intellectual disability and/or autism from Camberwell, South London, UK, and the initial follow-up data, taken when the subjects were adolescents and young adults (Shah 1986), are described in the present study. Changes in skills over time are presented within the categories of communication, self-care, and educational and cognitive skills, as assessed by the Handicaps, Behaviours and Skills schedule. The results indicated that skills had improved in many areas between times 1 and 2, but that this improvement was more noticeable for the children who had been youngest at time 1. The implications of these results and predictions for a further follow-up study are discussed.
Adolescent↗
Cell-specific glycoforms of sialoadhesin and CD45 are counter-receptors for the cysteine-rich domain of the mannose receptor.
We previously reported that CR-Fc, an Fc chimeric protein containing the cysteine-rich (CR) domain of the mannose receptor, binds to marginal zone metallophilic macrophages (Mo) and B cell areas in the spleen and to subcapsular sinus Mo in lymph nodes of naive mice (CR-Fc(+) cells). Several CR-Fc ligands were found in spleen and lymph node tissue lysates using ligand blots. In this paper we report the identification of two of these ligands as sialoadhesin (Sn), an Mo-specific membrane molecule, and the leukocyte common antigen, CD45. CR-Fc bound selectively to Sn purified from spleen and lymph nodes and to two low molecular weight isoforms of CD45 in a sugar-dependent manner. CR-Fc binding and non-binding forms of Sn, probably derived from CR-Fc(+) and CR-Fc(-) cells respectively, were selected from spleen lysates. Analysis of the glycan pool associated with the CR-Fc-binding form revealed the presence of charged structures resistant to sialidase, absent in the non-binding form, that could correspond to sulfated structures. These results confirm the identification of the CR region of the mannose receptor as a lectin. We also demonstrate that the same glycoprotein expressed in different cells of the same organ can display distinct sugar epitopes that determine its binding properties.
Animals↗
The CD45 tyrosine phosphatase regulates CD3-induced signal transduction and T cell development in recombinase-deficient mice: restoration of pre-TCR function by active p56(lck).
The pre-TCR complex regulates the transition from CD4(-)CD8(-) double-negative (DN) to CD4(+)CD8(+) double-positive (DP) thymocytes during T cell development. In CD45(-/-) mice there is an accumulation of DN cells, suggesting a possible role for CD45 in pre-TCR signaling. We therefore crossed CD45(-/-) with Rag-1(-/-) mice to investigate the signaling functions of the CD3 complex in DN thymocytes. Remarkably, treatment of Rag-1(-/-)/CD45(-/-) mice with a CD3 mAb caused maturation to the DP stage at only 3% of the level measured in Rag-1(-/-) mice. Furthermore, ligation of the CD3 complex on Rag-1(-/-) /CD45(-/-) thymocytes in vitro induced less tyrosine phosphorylation in specific proteins when compared to Rag-1(-/-) thymocytes. CD45(-/-) mice were also crossed with pLGFA mice expressing a constitutively active form of the lck tyrosine kinase which restored the DN to DP transition to near normal levels. Our results are consistent with a model in which CD45-activated p56(lck) is critical for pre-TCR signal transduction.
Animals↗
Induction in transgenic mice of HLA-A2.1-restricted cytotoxic T cells specific for a peptide sequence from a mutated p21ras protein.
Cytotoxic T cells (CTL) recognize short peptides that are derived from the proteolysis of endogenous cellular proteins and presented on the cell surface as a complex with MHC class I molecules. CTL can recognize single amino acid substitutions in proteins, including those involved in malignant transformation. The mutated sequence of an oncogene may be presented on the cell surface as a peptide, and thus represents a potential target antigen for tumour therapy. The p21ras gene is mutated in a wide variety of tumours and since the transforming mutations result in amino acid substitutions at positions 12, 13 and 61 of the protein, a limited number of ras peptides could potentially be used in the treatment of a wide variety of malignancies. A common substitution is Val for Gly at position 12 of p21ras. In this study, we show that the peptide sequence from position 5 to position 14 with Val at position 12-ras p5-14 (Val-12)-has a motif which allows it to bind to HLA-A2.1. HLA-A2.1-restricted ras p5-14 (Val-12)-specific CTL were induced in mice transgenic for both HLA-A2.1 and human beta2-microglobulin after in vivo priming with the peptide. The murine CTL could recognize the ras p5-14 (Val-12) peptide when they were presented on both murine and human target cells bearing HLA-A2.1. No cross-reactivity was observed with the native peptide ras p5-14 (Gly-12), and this peptide was not immunogenic in HLA-A2.1 transgenic mice. This represents an interesting model for the study of an HLA-restricted CD8 cytotoxic T cell response to a defined tumour antigen in vivo.
Amino Acid Sequence↗
Evaluation of ROM1 as a candidate gene in generalised progressive retinal atrophy in dogs.
Generalised progressive retinal atrophy (gPRA) is a heterogeneous group of hereditary diseases causing degeneration of the retina in dogs and other animals. The genetic origin is unknown in most cases. We have screened the coding sequence of the ROM1 gene for disease causing mutations in Tibetan Terriers, Miniature Poodles, Dachshunds and Chesapeake Bay Retrievers by single strand conformation polymorphism analysis (SSCP). Two polymorphisms have been identified by sequencing, one in exon 1 in all examined breeds (position 210: G-->A; Gly40Arg and position 252: G-->T; Ala53-Ser). Another polymorphism was present in exon 2 (position 1150: C-->T and position 1195: C-->T) segregating in Miniature Poodles. None of these polymorphisms were cosegregating with gPRA rendering a disease causing mutation in the ROM1 gene unlikely.
Animals↗
Aberrant TCR-mediated signaling in CD45-null thymocytes involves dysfunctional regulation of Lck, Fyn, TCR-zeta, and ZAP-70.
CD45 is a transmembrane phosphotyrosine phosphatase expressed on all nucleated hemopoietic cells. Targeting of CD45 exon 9 has generated a mouse line completely lacking CD45 expression (CD45-null) in which there are severe abnormalities in T cell development. Defects in TCR-mediated signals underlying these abnormalities have now been investigated using CD45-null T cells. No T cell proliferation was detected in response to a CD3 mAb. In thymocytes the p56(lck) and p59(fyn) tyrosine kinases were hyperphosphorylated, and p56(lck) was in its inactive conformation. Both basal and TCR-stimulated tyrosine phosphorylation of TCR-zeta and CD3-epsilon were much reduced, and TCR stimulation induced an abnormal p18 phosphoisomer of TCR-zeta previously noted in T cells stimulated by altered peptide ligands. These defects were associated with the failure of ZAP-70 kinase recruitment to the TCR-zeta chain. TCR coupling to the tyrosine phosphorylation of several proteins, including HS1 and p120(cbl), was also much reduced. However, TCR-induced signaling was not ablated, and significant inositol phosphate and calcium signals were observed in CD45-null thymocytes. Our molecular analysis suggests that the threshold for TCR signal transduction is greatly increased in CD45-null T cells, thus explaining the profound defects in thymic development.
Animals↗
Human histocompatibility leukocyte antigen (HLA)-G molecules inhibit NKAT3 expressing natural killer cells.
The crucial immunological function of the classical human major histocompatibility complex (MHC) class I molecules, human histocompatibility leukocyte antigen (HLA)-A, -B, and -C, is the presentation of peptides to T cells. A secondary function is the inhibition of natural killer (NK) cells, mediated by binding of class I molecules to NK receptors. In contrast, the function of the nonclassical human MHC class I molecules, HLA-E, -F, and -G, is still a mystery. The specific expression of HLA-G in placental trophoblast suggests an important role for this molecule in the immunological interaction between mother and child. The fetus, semiallograft by its genotype, escapes maternal allorecognition by downregulation of HLA-A and HLA-B molecules at this interface. It has been suggested that the maternal NK recognition of this downregulation is balanced by the expression of HLA-G, thus preventing damage to the placenta. Here, we describe the partial inhibition of NK lysis of the MHC class I negative cell line LCL721.221 upon HLA-G transfection. We present three NK lines that are inhibited via the interaction of their NKAT3 receptor with HLA-G and with HLA-Bw4 molecules. Inhibition can be blocked by the anti-NKAT3 antibody 5.133. In conclusion, NK inhibition by HLA-G via NKAT3 may contribute to the survival of the fetal semiallograft in the mother during pregnancy.
Cells, Cultured↗
Characterization of the Lancefield group C streptococcus 16S-23S RNA gene intergenic spacer and its potential for identification and sub-specific typing.
The 16S-23S RNA gene intergenic spacers of isolates of Streptococcus equi (n = 5), S. zooepidemicus (n = 5), S. equisimilis (n = 3) and S. dysgalactiae (n = 2) were sequenced and compared. There were distinct regions within the spacer, arranged in the order 1-9 for all S. equi and one S. zooepidemicus isolate and 1,2 and 4-9 for the remaining isolates. Region 4 was identical to the tRNA(ala) gene found in the 16S-23S intergenic spacers of other streptococci. Regions 1, 5, 6 and 7 had distinct variations, each conserved in different isolates. However, amongst the intergenic spacers there were different combinations of variant regions, suggesting a role for DNA recombination in their evolution. The intergenic spacer of all isolates of S. equi and one S. zooepidemicus isolate were almost identical. Primers derived from the variant sequences of regions 1 and 5 to 6 were used to group all S. zooepidemicus (n = 17) and S. equi (n = 5) into 1 of 8 types by polymerase chain reaction; three S. zooepidemicus isolates typed the same as S. equi. S. equi and S. zooepidemicus were clearly distinguishable from S. equisimilis and S. dysgalactiae which had shorter regions 5 and 6 and no region 7. Most homology for the group C sequences was found in previously published sequences for the 16S-23S intergenic spacers of S. anginosis, S. constellatus, S. intermedius, S. salivarius and S. agalactiae. A 75-90 nucleotide length shared with S. anginosus and S. intermedius in opposite orientations in the two main variants of region 6 supported the role for DNA recombination in the evolution of the spacer. The 16S-23S intergenic spacers indicate that S. zooepidemicus was the archetypal species for S. equi and that both are genetically more distant from S. equisimilis and S. dysgalactiae. The intergenic spacer can be used to identify specifically the group C streptococci and as an epidemiological marker for S. zooepidemicus.
Animals↗
Tyrosine phosphatases in T-cell development and signalling.
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Animals↗
T-cell antigen receptor signal transduction in CD45-/- thymocytes.
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Animals↗
Evaluation of trophoblast HLA-G antigen with a specific monoclonal antibody.
A monoclonal antibody to HLA-G has been generated by immunizing HLA-A2.1/human beta 2-microglobulin (beta 2 m) double transgenic mice with murine L cells transfected with both human beta 2 m and HLA-G. This monoclonal antibody, designated as G233, has been found not to cross-react with other HLA class I antigens when tested on numerous cell lines by flow cytometry. With immunohistology, all populations of extravillous trophoblast (cell columns, interstitial trophoblast, endovascular trophoblast, placental bed giant cells) were stained. An extensive range of adult and fetal tissues was also tested but none reacted with monoclonal antibody G233, including those previously reported to express HLA-G mRNA, indicating that the protein has a highly restricted distribution. Failure to detect HLA-G in the fetal thymus raises the question as to how T-cell tolerance to this antigen is induced. Immunoprecipitation of trophoblast surface proteins with monoclonal antibody G233 revealed a heavy chain of 39 kDa and a light chain of 12 kDa, indicating that HLA-G expressed on the surface of trophoblast is complexed with beta 2 m. However, sequential immunoprecipitation with monoclonal antibody W6/32 followed by monoclonal antibody G233 continued to detect a residual band of 39 kDa, suggesting that trophoblast surface HLA-G may also occur as free heavy chains not associated with beta 2 m. Immunoprecipitation followed by two dimensional gel electrophoresis showed that monoclonal antibody G233 recognizes several isoforms of HLA-G from trophoblast similar to the characteristic spot array previously described for HLA-G. This monoclonal antibody G233 will be highly useful in future experiments to elucidate the function of HLA-G.
Adult↗
Narratives of risk in occupational health and safety: why the 'good' boss blames his tradesman and the 'good' tradesman blames his tools.
Risk and its control are important themes in occupational health and safety. In the current regulatory framework, risk is conceptualised as a probabilistic expression of hazard potential. However, social meanings of risk in the workplace may be different. The social context of work shapes the ways that risk is understood in the workplace, yet little research in occupational health and safety acknowledges it. A few studies of risk have used qualitative research methods to elicit understandings of risk at work; however, little research explores the experiences of both employers and employees. This study describes the narratives of risk in occupational health and safety of employers and employees in the Victorian painting industry. Using ethnographic methods, we collected data about the contexts in which risk is experienced and the sources of risk that each group identifies. These narratives reveal that risk in the painting industry is constructed through the interactions of three factors: the social context, the hierarchical structure of the industry and the shared assumptions about risk control through the individual skills and responsibilities. The narratives explain why occupational health and safety strategies focusing solely on individual behaviour change or technical measures will be unsuccessful.
Accidents, Occupational↗
CD45-null transgenic mice reveal a positive regulatory role for CD45 in early thymocyte development, in the selection of CD4+CD8+ thymocytes, and B cell maturation.
The CD45 transmembrane glycoprotein has been shown to be a protein phosphotyrosine phosphatase and to be important in signal transduction in T and B lymphocytes. We have employed gene targeting to create a strain of transgenic mice that completely lacks expression of all isoforms of CD45. The spleens from CD45-null mice contain approximately twice the number of B cells and one fifth the number of T cells found in normal controls. The increase in B cell numbers is due to the specific expansion of two B cell subpopulations that express high levels of immunoglobulin (IgM) staining. T cell development is significantly inhibited in CD45-null animals at two distinct stages. The efficiency of the development of CD4-CD8- thymocytes into CD4+ CD8+ thymocytes is reduced by twofold, subsequently the frequency of successful maturation of the double positive population into mature, single positive thymocytes is reduced by a further four- to fivefold. In addition, we demonstrate that CD45-null thymocytes are severely impaired in their apoptotic response to cross-linking signals via T cell receptor (TCR) in fetal thymic organ culture. In contrast, apoptosis can be induced normally in CD45-null thymocytes by non-TCR-mediated signals. Since both positive and negative selection require signals through the TCR complex, these findings suggest that CD45 is an important regulator of signal transduction via the TCR complex at multiple stages of T cell development. CD45 is absolutely required for the transmission of mitogenic signals via IgM and IgD. By contrast, CD45-null B cells proliferate as well as wild-type cells to CD40-mediated signals. The proliferation of B cells in response to CD38 cross-linking is significantly reduced but not abolished by the CD45-null mutation. We conclude that CD45 is not required at any stage during the generation of mature peripheral B cells, however its loss reveals a previously unrecognized role for CD45 in the regulation of certain subpopulations of B cells.
ADP-ribosyl Cyclase↗
Nonclassical HLA-G molecules are classical peptide presenters.
BACKGROUND: The physiological functions of the classical HLA (human leukocyte antigen) molecules, HLA-A, HLA-B and HLA-C, are to present peptides to T cells and to inhibit the activity of natural killer cells. In contrast, the functions of nonclassical HLA-molecules, such as HLA-E, HLA-F and HLA-G, remain to be established. The expression of HLA-G is largely limited to the placental trophoblast, where it might mediate protection of the fetus from rejection by the mother. Achieving the aim of understanding the function of HLA-G should be facilitated by information on the biochemical properties of HLA-G molecules, especially on their potential ability to act as peptide receptors. RESULTS: To study peptide presentation by HLA-G, we used stably transfected LCL721.221 cells as a source of HLA-G molecules and analysed the spectrum of extracted peptides by individual and pool sequencing. Our results indicate that HLA-G molecules, like classical HLA molecules, are associated with a wide array of peptides derived from cellular proteins. Peptides presented by HLA-G usually consisted of 9 amino acids, and adhered to a specific sequence motif, with anchor residues at position 2 (isoleucine or leucine), position 3 (proline) and the carboxy-terminal position 9 (leucine). Thus, the HLA-G peptide ligand motif follows the principles of classical HLA motifs, although it displays its own unique features. Peptide-binding assays indicated that two of the three anchor residues were sufficient for binding, and that the three natural HLA-G ligands that we identified bound, not only to HLA-G, but also to HLA-A2. This was not surprising, because the binding pockets of HLA-A2 and HLA-G overlap in their ability to recognize anchor residues at positions 2 and 9. Likewise, some, but not all, HLA-A2 peptide ligands could also bind to HLA-G. CONCLUSIONS: Nonclassical HLA-G molecules present peptides essentially in the same way as classical HLA molecules do. We determined the peptide motif that is specifically recognized by HLA-G; its basic features are described by the sequence XI/LPXXXXXL: This information should help to elucidate the physiological role of HLA-G molecules at the fetal-maternal interface. Most likely, this role is to protect fetal cells from lysis by natural killer cells, and possibly to present foreign peptides to a class of T cells that has not yet been identified.
Amino Acid Sequence↗