Showing papers by "John Radcliffe Hospital published in 1989"

Antigen Recognition by Class I-Restricted T Lymphocytes

Abstract: The work discussed here offers a unified view of T-cell recognition and suggests that class-I and class-II molecules have a closely related function in the presentation of peptides to T lymphocytes. The epitopes recognized by class I-restricted T cells that have been defined with peptides in the 4-6 hr lysis assay have all been derived from endogenously synthesized proteins expressed by virus infected or transfected cells. Evidence is accumulating that a cytoplasmic degradation system may be involved in the generation of these epitopes. The analysis of the specificity of CTL responses with synthetic peptides has demonstrated the control of immune responses to isolated epitopes by class-I genes and the great diversity of the receptor repertoire for individual class-I-restricted epitopes.

Association of class I major histocompatibility heavy and light chains induced by viral peptides.

Abstract: We describe a cell in which association of a major histocompatibility complex class I heavy chain with beta 2-microglobulin is induced by a peptide derived from influenza nucleoprotein. Association of antigenic peptides with the binding site of class I molecules may be required for correct folding of the heavy chain, association with beta 2-microglobulin and transport of the antigen-MHC complex to the cell surface.

Intercellular adhesion molecule-1 is an endothelial cell adhesion receptor for Plasmodium falciparum.

Abstract: The primary event in the pathogenesis of severe malaria in Plasmodium falciparum infection is thought to be adherence of trophozoite- and schizont-infected erythrocytes to capillary endothelium, a process called sequestration. Identifying the endothelial molecules used as receptors is an essential step in understanding this disease process. Recent work implicates the membrane glycoprotein CD36 (platelet glycoprotein IV; refs 2-5) and the multi-functional glycoprotein thrombospondin as receptors. Although CD36 has a widespread distribution on microvascular endothelium, it may not be expressed on all capillary beds where sequestration occurs, especially in the brain. The role of thrombospondin in cell adhesion, in vitro or in vivo, is less certain. We have noticed that some parasites bind to human umbilical-vein endothelial cells independently of CD36 or thrombospondin. To screen for alternative receptors, we have developed a novel cell-adhesion assay using transfected COS cells, which confirms that CD36 is a cell-adhesion receptor. In addition, we find that an endothelial-binding line of P. falciparum binds to COS cells transfected with a complementary DNA encoding intercellular adhesion molecule-1. As this molecule is widely distributed on capillaries and is inducible, this finding may be relevant to the pathogenesis of severe malaria.

An autosomal transcript in skeletal muscle with homology to dystrophin.

Abstract: The Duchenne muscular dystrophy (DMD) gene has been localized to chromosome Xp21 and codes for a 14-kilobase (kb) transcript and a protein called dystrophin, of relative molecular mass 427,000. Dystrophin is associated with the cytoplasmic face of muscle fibre membranes and its C-terminal domain is thought to mediate membrane attachment. Although N-terminal and central domain structures share common features with other cytoskeletal components, no significant sequence similarity between the C-terminal region of dystrophin and other previously characterized proteins has been described. Here we report that fragments from the C-terminal domain of the DMD complementary DNA detect a closely related sequence which exhibits nucleic-acid and predicted amino-acid identities with dystrophin of approximately 65 and 80%, respectively. The dystrophin-related sequence identifies a 13-kb transcript in human fetal muscle and maps to chromosome 6. Thus, dystrophin may be a member of a family of functionally related large structural proteins in muscle.

KP1: a new monoclonal antibody that detects a monocyte/macrophage associated antigen in routinely processed tissue sections.

Abstract: A new monoclonal antibody, KP1, raised against a lysosomal fraction of human lung macrophages, recognises a fixation-resistant epitope in a wide variety of tissue macrophages (such as Kupffer cells germinal centre, splenic, and lamina propria macrophages), and in granulocyte precursors. Its broad reactivity with cells of the mononuclear phagocytic lineage was established by testing on routinely processed samples of normal and reactive lymphoid tissues. Interdigitating reticulum cells were unstained or showed limited cytoplasmic staining while Langerhans' cells and follicular dendritic reticulum cells were unreactive. KP1 recognises a molecule of about 110 kilodaltons in macrophage-rich human tissue when tested by either immunoprecipitation or Western blotting (although the latter procedure also shows two additional components with molecular weights of 70 and 40 kilodaltons). KP1 should be of considerable value for studying disorders of the monocyte/macrophage system, including both reactive and neoplastic states (such as true histiocytic proliferations).

HLA-DR4 subtype frequencies in rheumatoid arthritis indicate that DRB1 is the major susceptibility locus within the HLA class II region.

Abstract: Susceptibility to rheumatoid arthritis (RA) may be due to the presence of shared functional epitopes common to the HLA-DR beta chains of several RA-associated haplotypes. We have obtained direct evidence for this hypothesis by using the polymerase chain reaction and sequencing the DRB1 and DQB1 genes from RA patients. A highly conserved epitope present on DR beta chains of DR4 and DR1 haplotypes was found in 83% of 149 patients with classical or definite RA but was found in only 46% of 100 control individuals (P less than 0.0001). Two Dw subtypes of DR4 (Dw4 and Dw14) were associated with disease susceptibility but two other subtypes (Dw10 and Dw13) were not. Sequence differences between these subtypes implicate those residues around the putative antigen binding site of the DR beta molecule in the pathogenesis of RA. These data provide a basis for understanding host susceptibility to RA at a molecular level.

Ancient bone DNA amplified

Abstract: Reports the successful extraction and amplification of DNA from human bones between 300 and 5500 years of age. Genetic information can be recovered from ancient skeletal material if contamination by modern DNA is avoided. Describes experimental technique and results on a range of bone samples.

The penetration of antibiotics into aggregates of mucoid and non-mucoid Pseudomonas aeruginosa.

Abstract: Cells of mucoid and non-mucoid Pseudomonas aeruginosa in colonies were at least one-thousandfold less sensitive to the antibiotics tobramycin or cefsulodin than were cells of the same bacteria in dispersed suspension. We did not detect any difference between the mucoid form and the non-mucoid form in the antibiotic sensitivity of colonies, from which we infer that the exopolysaccharide of the mucoid form does not contribute to colony-resistance by forming a barrier to antibiotic diffusion. Mathematical models were constructed in order to estimate time-courses of penetration of tobramycin and cefsolodin into biofilms and microcolonies of mucoid and non-mucoid P. aeruginosa. For tobramyen penetration, adsorption of antibiotic to the exopolysaccharide of the glycocalyx and antibiotic uptake by cells were taken into account in the calculations. The longest time-period for the concentration of tobramycin at the base of a biofilm 100 µm deep to rise to 90% of the concentration outside the biofilm was predicted to be 2·4 h. For cefsulodin penetration, irreversible hydrolysis catalysed by β-lactamase was taken into account, using β-lactamase levels taken from the literature. The calculations predicted that the cefsulodin concentration at the base of antifilm 100 µm deep would rise to 90% of the external concentration in 29 s when the β-lactamase was synthesized at the basal level. For a similar biofilm of bacteria synthesizing enhanced levels of β-lactamase (‘derepressed’), the concentration of cefsulodin at the base was calculated to rise to 41% of the external concentration in about 50s and then remain at that level. This was despite the fact that cefsulodin is a poor substrate for this β-lactamase.

A translocation involving a specific breakpoint (q35) on chromosome 5 is characteristic of anaplastic large cell lymphoma ('Ki-1 lymphoma').

Abstract: Summary Two cases of non-Hodgkin's lymphoma are reported in which a chromosomal translocation was observed involving the same site (q35) on the long arm of chromosome 5. The other breakpoint involved in the translocation was chromosome 2 (p23) in one case and chromosome 3 (q12) in the other. Both cases were large cell lymphomas expressing CD30 antigen (‘Ki-1 lymphoma'). One was clearly of T lymphoid origin, the other probably B cell derived. One other case of a Ki-1 lymphoma with 2;5 translocation (involving the same breakpoint on chromosome 5) has been reported previously, and it is suggested that this cytogenetic abnormality may be specifically associated with Ki-1 lymphoma. The literature contains a further eight cases of lymphoid neoplasms with a translocation involving a breakpoint at q35 on chromosome 5. They have all been described as cases of‘malignant histiocytosis’, but the present findings make it likely that these cases were in reality also examples of Ki-1 lymphoma. The breakpoint at the q35 region on chromosome 5 is close to the position of the fms proto-oncogene, suggesting that an abnormality affecting this gene might possibly play a causal role in ‘Ki-1 lymphoma’. However, DNA restriction fragment analysis of the present cases showed no evidence that the breakpoint on chromosome 5 involves the fms gene or its immediate vicinity.

Identification of susceptibility loci for insulin-dependent diabetes mellitus by trans-racial gene mapping

Abstract: INSULIN-dependent (type I) diabetes mellitus (IDDM) follows an autoimmune destruction of the insulin-producing β-cells of the pancreas1,2. Family and population studies indicate that predisposition is probably polygenic3. At least one susceptibility gene lies within the major histocompatibility complex and is closely linked to the genes encoding the class II antigens, HLA-DR and HLA-DQ (refs 3,4). Fine mapping of susceptibility genes by linkage analysis in families is not feasible because of infrequent recombination (linkage disequilibrium) between the DR and DQ genes. Recombination events in the past, however, have occurred and generated distinct DR–DQ haplotypes, whose frequencies vary between races4–6. DNA sequencing and oligonucleotide dot-blot analysis of class II genes from two race-specific haplotypes indicate that susceptibility to IDDM is closely linked to the DQA1 locus and suggest that both the DQB1 (ref. 7) and DQA1 genes contribute to disease predisposition.

Sliding hip screws: modes of failure

Abstract: The modes of failure of the sliding hip screw devices were investigated by reviewing 223 cases. There were 35 mechanical failures. Two of these occurred when the components separated in highly comminuted fractures. The use of the locking screw is recommended to prevent this. The other 33 occurred when the device had lost its sliding action. The reasons for this included jamming, insufficient slide being available and additional fixation. To reduce the complication rate it is recommended that any additional fixation (such as cerclage wires) should be used with care to ensure that they do not block the barrel. For patients with short femoral necks, a shorter barrelled version of the device should be used as it would have a greater sliding capacity. Guidelines for its use are given.

Snake venoms in science and clinical medicine 1. Russell's viper: biology, venom and treatment of bites

Abstract: Russell's viper, Vipera russelli (Shaw), is distributed erratically in 10 south Asian countries and is a leading cause of fatal snake bite in Pakistan, India, Bangladesh, Sri Lanka, Burma and Thailand. In Burma it has been the 5th most important cause of death. Its venom is of great interest to laboratory scientists and clinicians. The precoagulant activity of the venom was used by Macfarlane and others to elucidate the human clotting cascade. Up to 70% of the protein content is phospholipase A2, present in the form of at least 7 isoenzymes. Possible clinical effects of the enzyme include haemolysis, rhabdomyolysis, pre-synaptic neurotoxicity, vasodilatation and shock, release of endogenous autacoids and interaction with monoamine receptors. Russell's viper bite is an occupational hazard of rice farmers throughout its geographical range. Defibrination, spontaneous haemorrhage, shock and renal failure develop with frightening rapidity. In several countries, Russell's viper bite is the commonest cause of acute renal failure. There is a fascinating geographical variation in the clinical manifestations, doubtless reflecting differences in venom composition. Conjunctival oedema is unique to Burma, acute pituitary infarction to Burma and south India, and rhabdomyolysis and neurotoxicity to Sri Lanka and south India. Treatment with potent specific antivenom rapidly controls bleeding and clotting disorders, but may not reverse nephrotoxicity and shock. Causes of death include shock, pituitary and intracranial haemorrhage, massive gastrointestinal haemorrhage and acute tubular necrosis or bilateral renal cortical necrosis. The paddy farmer and the Russell's viper coexist in fragile symbiosis. The snake controls rodent pests but inevitably interacts with man, often with mutually disastrous results.

A selective differential medium for the isolation of Listeria monocytogenes

Abstract: A new medium has been developed for the isolation of Listeria monocytogenes from clinical specimens with a mixed flora. Almost complete inhibition of unwanted organisms was achieved and recognition of colonies of Listeria spp. was usually possible after 24 h using the aesculin-ferric ammonium citrate indicator system. Compared to McBride agar the new medium was more inhibitory to representative contaminating species in pure culture and more successful in isolating small numbers of L. monocytogenes from artificially seeded clinical specimens.

Chromosome maps of man and mouse. IV.

Abstract: SUMMARY Current knowledge of man-mouse genetic homology is presented in the form of chromosomal displays, tables and a grid, which show locations of the 322 loci now assigned to chromosomes in both species, as well as 12 DNA segments not yet associated with gene loci. At least 50 conserved autosomal segments with two or more loci have been identified, twelve of which are over 20 cM long in the mouse, as well as five conserved segments on the X chromosome. All human and mouse chromosomes now have conserved regions; human 17 still shows the least evidence of rearrangement, with a single long conserved segment which apparently spans the centromere. The loci include 102 which are known to be associated with human hereditary disease; these are listed separately. Human parental effects which may well be the result of genomic imprinting are reviewed and the location of the factors concerned displayed in relation to mouse chromosomal regions which have been implicated in imprinting phenomena.

Detection of T cells in paraffin wax embedded tissue using antibodies against a peptide sequence from the CD3 antigen.

Abstract: Rabbit polyclonal antibodies were raised against a proline rich, peptide sequence, comprising 13 amino acids, in the cytoplasmic domain of the CD3 epsilon chain. Immunoprecipitation experiments showed that this antibody preparation recognised the CD3 antigen on human T lymphoblasts. The antibody stained normal T cells strongly in tissue sections which had been fixed in formalin or Bouin's solution and embedded in paraffin wax. Its reactivity with T cell lymphoma, when evaluated on a series of 96 previously phenotyped cases, closely agreed with the results obtained on cryostat sections. These results indicate that the specific detection of T cells in routinely processed tissue biopsy specimens is now technically feasible on a wide scale in diagnostic laboratories using CD3 peptide antibodies, and they also suggest that in future the use of anti-peptide antibodies may detect other lineage specific antigenic markers in paraffin wax sections.

Problems in determining the etiology of community-acquired childhood pneumonia.

Abstract: Fifty-seven children ages 1 month to 12 years hospitalized because of community-acquired pneumonia were compared with age-matched controls who had acute asthma without pneumonia to test the value of rapid bacterial antigen detection and clinical and radiographic criteria for diagnosis of bacterial pneumonia. Bacterial pneumonia, defined on the basis of positive cultures of blood or pleural fluid, was diagnosed in 4 children (7%), 1 of whom also had viral pneumonia. Viral pneumonia, defined as a positive nasopharyngeal sample or positive serology, was diagnosed in 20 children (35%). Serum and concentrated urine were tested by latex agglutination (Wellcogen) for Haemophilus influenzae type b and pneumococcal antigens and by countercurrent immunoelectrophoresis for pneumococcal antigens. Pneumococcal antigen could not be detected in serum or urine from 3 children with culture-proved pneumococcal pneumonia, indicating poor sensitivity of the tests. In contrast apparent H. influenzae type b antigenuria was detected by latex agglutination in 4 of 40 children with pneumonia but also in 5 of 57 controls, and a sensitive enzyme-linked immunosorbent assay for polyribosyl ribitol (PRP) phosphate antigen showed that all 9 cases were false positives. The specificity of H. influenzae type b antigen detection was thus poor. Children with viral and bacterial pneumonia could not be distinguished by radiographic or clinical criteria (symptoms, fever) or by total or differential white blood cell counts, serum C-reactive protein or nasal or serum interferon levels. It is not possible to distinguish reliably childhood viral from bacterial pneumonia clinically or by rapid diagnostic tests.

A human macrophage-associated antigen (CD68) detected by six different monoclonal antibodies.

Abstract: Antibodies grouped together by the Third Workshop on Leucocyte Differentiation Antigens on the basis of pan-macrophage reactivity on tissue sections were analysed in immunoprecipitation experiments. Antibodies Y2/131, EBM11, Ki-M6 and Ki-M7 all precipitated antigens of Mr 110,000 which were shown to be identical by preclearing experiments. In addition a recently produced antibody, KP1, which identifies macrophages in paraffin-embedded tissue, was shown to recognize the same antigen. The antibodies were tested on murine cells transfected with two clones, which had been isolated by screening a cDNA library with antibodies Y1/82A and EBM11. Cells transfected with the longer cDNA clone, coding for a molecule of Mr 110,000, reacted with antibodies Y2/131, EBM11, Y1/82A and Ki-M6, whilst the shorter clone, encoding a molecule of Mr 70,000 gave the same result except that it did not induce expression of the Ki-M6 epitope. KP1 antibody did not recognize any transfectants, possibly because of differences in glycosylation by the transfected cell line compared with human tissue. Five of the six antibodies appear to recognize different epitopes (the sixth, Ki-M7, not having been evaluated in this way). It was concluded that these six antibodies react with a macrophage-associated antigen for which the gene has been cloned. This group of antibodies has recently been designated CD68 by the Fourth Workshop on Human Leucocyte Differentiation Antigens.

Mucosal involvement in systemic and chronic cutaneous lupus erythematosus.

Abstract: The prevalence and pattern of mucosal involvement in 121 patients with lupus erythematosus (LE) was investigated. Fifty-three patients had systemic LE (SLE) and 68 patients had chronic cutaneous LE (CCLE). Twenty-one per cent (11/53) of patients with SLE and 24% (16/68) of patients with CCLE had signs of mucosal involvement, but the pattern of involvement differed in the two groups. Nasal mucosal lesions were a feature in 2% (I/53) of patients with SLE and 9% (6/68) of patients with CCLE. Hyperkeratotic lichen planus-like plaques on buccal mucosa and the palate occurred in 9% (6/68) of patients with CCLE and 4% (2/53) of patients with SLE. Episcleritis occurred in 9% (5/53) of patients with SLE and not seen in CCLE. Erythematous plaques on the lower eyelids were present in 6% (4/68) of patients with CCLE and these were associated with conjunctival scarring in two patients. Vulval lesions were present in 5% (2/42) of female patients with CCLE. Oral plaques may occur when the disease is relatively quiescent elsewhere. The prevalence of mucosal involvement in lupus is underestimated as the lesions may be asymptomatic.

Transcervical resection of endometrium in women with menorrhagia.

Abstract: As an alternative to hysterectomy 16 women with menorrhagia were treated with hysteroscopic transcervical resection of the endometrium with an unmodified urological resectoscope. Twelve patients requested total resection of the endometrial lining with the intention of producing amenorrhoea, and four chose partial resection and hypomenorrhoea. Surgery was completed successfully in 15; the remaining woman, who had an acutely retroflexed uterus, sustained a uterine perforation during insertion of the rigid hysteroscope. There were no important postoperative complications, and 13 patients were discharged from hospital the day after operation. Follow up for up to six months showed beneficial effects on the duration of menses and the subjective assessment of menstrual blood loss and pain in the treated women, six of them becoming amenorrhoeic after total resection. Hysteroscopy at three months in 13 patients showed fibrosis confined to the upper half of the uterine cavity. Endouterine biopsy specimens showed the presence of microscopic deposits of normal endometrium in 10 women. Although these results are preliminary, transcervical resection of the endometrium may have an important role in managing this common complaint.

Treatment of malaria: some considerations and limitations of the current methods of assessment

Abstract: The currently used methods for assessing the therapeutic response to antimalarial drugs are relatively imprecise and insensitive. These methods are inadequate in severe malaria when the objectives of treatment are to save life and prevent complications. Very large studies are needed to demonstrate significant differences in mortality, but measurement of the rates of clinical, biochemical, and parasitological response may provide useful comparative information. Definitions, assessment criteria, procedures, and data collection forms should be standardized and evaluated prospectively. Antimalarial drug treatment in different clinical situations should be assessed in terms of the balance between the risks of drug toxicity and the benefits of the antimalarial drug action. This balance is considerably different in severe falciparum malaria compared with uncomplicated malaria infections.

Tissue cyst rupture in mice chronically infected with Toxoplasma gondii. An immunocytochemical and ultrastructural study.

Abstract: The incidence and effect of tissue cyst rupture in the brains of mice chronically infected withToxoplasma gondii was studied by immunocytochemistry and electron microscopy. Cyst rupture was extremely rare (2 of 750 tissue cysts) irrespective of the interval post-infection. The event was associated with a rapid cell-mediated immune response, giving rise to microglial or inflammatory nodules. Macrophages were observed to engulf and degrade the cystozoites and cyst debris. Initially, the nodules contained large amounts of immunologically reactive material, but this was degraded with the majority (94%) of lesions containing no recognizable parasites orToxoplasma antigens. There was little evidence of parasite multiplication or new cyst formation associated with cyst rupture. This study shows that although intermittent cyst rupture occurs, in immunocompetent individuals the immune response limits the potential damage from the release of large numbers of infective organisms to small microglial/inflammatory nodules.

Studies on morphine disposition: influence of renal failure on the kinetics of morphine and its metabolites

Abstract: The influence of renal failure on the disposition of morphine and its metabolites was studied in nine patients with end-stage renal failure undergoing transplantation, and compared with five healthy anaesthetized patients. All patients received morphine sulphate pentahydrate 10 mg i.v. over 30 s, as part of a balanced anaesthetic technique. Venous blood samples were collected for up to 24 h, and plasma concentrations of morphine, morphine-3-glucuronide (M3G), and morphine-6-glucuronide (M6G) assayed by a differential radioimmunoassay method. There were no differences between the two groups for morphine elimination half-life (renal failure: 290 min; anaesthetized controls: 286 min), or clearance (renal failure: 533 ml min-1; controls 741 ml min-1). However, the volume of distribution at steady state was greater in the control group (241 litre v. 141 litre; P = 0.002). The peak concentrations of M3G and M6G were greater in the renal transplant patients (P = 0.001 and P = 0.01, respectively), as were the AUC (0-24 h) (P = 0.002 and P = 0.002). M6G has been shown to possess analgesic properties in both man and experimental animals, and therefore the increased AUC for M6G may contribute to the prolonged effect seen with morphine when given to patients with impaired renal function.

Systemic and forearm vascular resistance changes after upright bicycle exercise in man.

Abstract: 1. Blood pressure, cardiac function and forearm blood flow following voluntary maximal upright bicycle exercise were studied in thirteen normal volunteers in a cross-over design against a control day. 2. After exercise there was a short-lived (5-10 min) increase in systolic blood pressure, peak aortic blood velocity and aortic acceleration suggesting a persistence of the positive inotropic influence of exercise. 3. Systemic vasodilation, which was seen immediately exercise stopped, lasted at least 60 min. This was associated with a reduction in diastolic blood pressure for the whole hour. After 30 min systolic blood pressure was also reduced. Heart rate and cardiac output were still significantly elevated and systemic vascular resistance still reduced at 60 min post-exercise. 4. A non-exercising limb vascular bed (forearm) showed a marked vasodilation for 1 h after predominately leg exercise indicating the presence of a vasodilatory influence affecting vascular beds other than the exercising muscle groups.