Showing papers by "John Radcliffe Hospital published in 1983"

Alpha-thalassaemia caused by a polyadenylation signal mutation.

Abstract: Most eukaryotic messenger RNAs have the sequence AAUAAA 11–30 nucleotides from the 3′-terminal poly(A) tract1,2. Since this is the only significant sequence homology in the 3′ non-coding region it has been suggested that it may be a recognition site for enzymes involved in polyadenylation and/or termination of polymerase II transcription2–4. This idea is strengthened by observations on the effect of deletion mutations in or around the AATAAA sequence on polyadenylation of late simian virus 40 (SV40) mRNA; removal of this sequence prevents poly(A) addition3. Naturally occurring variants ofthis hexanucleotide are rare5–11 and hitherto their functional significance has not been assessed. We have now identified a human α2-globin gene which contains a single point mutation in this hexanucleotide (AATAAA → AATAAG). The paired α1 gene on the same chromosome is completely inactivated by a frame-shift mutation. This unique combination has enabled the expression of the mutant α2 gene to be studied in vivo where it has been found that the accumulated level of α2-specific mRNA in erythroid cells is reduced. Furthermore, readthrough transcripts extending beyond the normal poly(A) addition site are detected in mRNA obtained from HeLa cells transfected with cloned DNA from the mutant α2 gene, suggesting that the single nucleotide change in the AATAAA sequence is the cause of its abnormal expression.

A human lymphocyte‐associated antigen involved in cell‐mediated lympholysis

Abstract: Human lymphocyte function antigen (HLFA) is a cell surface protein defined by two monoclonal antibodies MHM23 and MHM24. It is present on both B and T lymphocytes but in greater amounts on the latter. Both antibodies precipitated antigen, from radiolabeled HSB-2 cells, which ran as two chains on sodium dodecyl sulfate polyacrylamide gel electrophoresis at 180 and 94 kDa. Neither antibody inhibited binding of the other, indicating that distinct epitopes were recognized. Both antibodies were shown to inhibit HLA-restricted lysis of influenza virus-infected and Epstein-Barr virus-transformed target cells by cytotoxic T lymphocytes. Blocking occurred at the level of the effector cells and in the presence of subsaturating concentrations of antibody. Both reagents also inhibited lysis of K562 cells, mediated by natural killer cells. These blocking effects differ from the inhibitory effects of monoclonal anti-HLA ABC and anti-suppressor cytotoxic T cell antibodies which inhibit only HLA-restricted lysis when present in saturating amounts. It is concluded therefore that HLFA is likely to be involved in the nonspecific adherence or lytic functions of killer cells rather than specific antigen recognition.

Interaction of L. pneumophilia and a free living amoeba (Acanthamoeba palestinensis).

Abstract: Co-cultivation of Legionella pneumophila serogroup I and Acanthamoeba palestinensis in Neff's medium at 35 degrees C resulted in the intracellular multiplication of the bacteria as demonstrated by electron microscopy and immunofluorescence. In the closed experimental system used, the number of legionellae rose from 10(7) colony forming units (c.f.u.)/ml initially to a maximum of 10(10) c.f.u./ml on day 5. Legionellae were seen in expelled phagosomes, in some amoebae filling the cytoplasm and in others in which the process of encystment appeared to have commenced. At 20 degrees C the acanthamoebae phagocytosed and digested the legionellae. The bacteria disappeared from the co-cultivation flask by day 2 but reappeared in low numbers (10(2) c.f.u./ml) by day 6 suggesting that even at this temperature some intra-amoebal multiplication occurred.

Immunoenzymatic staining of haematological samples with monoclonal antibodies.

Abstract: Summary. This paper describes the use of immunoenzymatic techniques (and in particular a recently developed immuno-alkaline phosphatase procedure) for labelling haematological samples with monoclonal antibodies. Since cells are smeared and fixed before staining it is possible to combine optimal preservation of cellular detail with visualization of positive labelling. Additional advantages over conventional immunofluorescent procedures for detecting cellular antigens include the fact that samples may be stored for long periods both before and after staining, and that double labelling may readily be performed (either by combining immunoenzymatic staining with T cell resetting or by performing immunoperoxidase and immuno-alkaline phosphatase techniques sequentially). Furthermore, these methods may be applied to samples containing too few cells for conventional examination (e.g. samples of cerebrospinal fluid). A total of 16 different antigens (including HLA-DR, common ALL antigen and antigens associated with T cells, B cells, erythroid cells and megakaryocytes) were demonstrated by immuno-enzymatic staining on a range of normal and neoplastic haematological samples. It is concluded that this approach to cellular antigen labelling is of potential value not only in routine haematological diagnosis, but also for research in many immunological and haematological fields.

Metabolic and endocrine consequences of depriving preterm infants of enteral nutrition.

Abstract: Plasma enteroglucagon, pancreatic polypeptide, gastrin, motilin, neurotensin, gastric inhibitory polypeptide, secretin, vasoactive intestinal peptide and blood glucose, alanine, ketone bodies, lactate and pyruvate were measured on the sixth postnatal day in (a) a group of 10 preterm infants who on account of hyaline membrane disease had not received enteral feeding since birth and (b) before and at 55, 90, and 120 minutes after feeding in a group of healthy preterm infants fed three-hourly on human milk. Gut hormones were also measured in umbilical venous cord blood. The infants receiving regular boluses of milk from birth demonstrated postnatal surges in preprandial concentrations of gut hormones together with cyclical hormonal responses to feeding. None of these changes were seen in infants receiving intravenous fluids. The latter infants also had lower concentrations of blood alanine, glycerol and hydroxybutyrate and lacked the phasic changes in intermediary metabolites seen in the infants receiving enteral boluses of milk. Thus deprivation of enteral feeding results in a profound alteration of the metabolic and endocrine milieu which may have important effect on the process of adaptation to postnatal life.

Thalassaemia intermedia in Cyprus: the interaction of α and β thalassaemia

Abstract: Summary. Restriction endonuclease analysis has been performed on the α and β globin gene clusters of 57 Cypriots homozygous for β thalassaemia, 30 with the transfusion dependent form of the condition (thalassaemia major) and 27 who are less severely affected (thalassaemia intermedia). There was a significant difference in the incidence of α thalassaemia between the two groups: 14/27 of the patients with thalassaemia intermedia also had deletion forms of a thalassaemia, while only 4/30 of the patients with thalassaemia major were similarly affected. Thus in Cypriot patients who are homozygous for β thalassaemia the co-inheritance of a thalassaemia is an important factor in determining the clinical course.

Lectin-like polypeptides of P. falciparum bind to red cell sialoglycoproteins.

Abstract: Attempts to control human malaria by immunological means could be compromised by antigenic variability within and between different strains of malarial parasites1 A useful alternative approach might be to block parasite antigens which are important in the mechanisms of invasion of red cells As the major human parasite Plasmodium falciparum is highly specific for human red cells, isolation of the proteins involved in the recognition of red cells by this parasite might be of particular value Recent studies suggest that the major red cell sialoglycoproteins (SGPs), glycophorins A, B and possibly C, may carry the sites recognized by the parasite2-4 Furthermore, because certain carbohydrates present on SGPs such as N-acetylglucosamine are able to block invasion by the parasite5, they may be involved in the initial interaction between parasite and red cell We have now identified parasite proteins which bind to SGP or N-acetylglucosamine on Sepharose 4B columns Three proteins, of molecular weights (MWs) 140,000 (140K), 70K and 35K, seem to be specifically bound by N-acetylglucosamine

β + Thalassaemia—Portuguese type: clinical, haematological and molecular studies of a newly defined form of β thalassaemia

Abstract: We have characterized 14 patients in 10 families with a mild form of homozygous beta thalassemia which has not been previously well defined. As these patients originate from a small area of northern Portugal we propose to call this beta + thalassaemia--Portuguese type. Clinically, the homozygotes range from asymptomatic to thalassaemia intermedia and they are characterized by low levels of HbF, less than 20%, indicating only a mild deficit in beta globin production. Heterozygotes are indistinguishable from those with the more common types of beta thalassaemia as regards red cell morphology, haemoglobin analysis and globin chain synthesis studies. Globin gene mapping excluded the presence of alpha thalassaemia in these patients and demonstrated no abnormalities in the beta-like globin gene cluster. Restriction enzyme site polymorphisms around the beta gene cluster are identical on both chromosomes in all of the homozygotes, confirming their homogeneity.

Comparative distribution of fibronectin and type III collagen in normal human tissues

Abstract: The distribution of fibronectin (FN) and type III collagen (IIIC) in normal adult human tissues have been directly compared using immunofluorescence and immunoperoxidase techniques on fresh frozen and formalin-fixed paraffin embedded material. Although in many tissues localisation of these two proteins appeared similar, two major differences were identified: (1) Where the ratio of extracellular matrix to cells is high (e.g. in breast, intestinal submucosa), FN was scanty and present predominantly in association with cells, whether of epithelial, endothelial or mesenchymal origin. IIIC was present diffusely throughout interstitial connective tissue. (2) In the highly specialised vascular beds of spleen and renal glomeruli, FN was abundant and accompanied by little or no IIIC. It is postulated that these differences reflect a generalised more intimate association of FN with cell surfaces and basal laminae which is not always discernible by light microscopy. Proximity of FN and IIIC may nevertheless be important for cell-matrix interactions. It was also noted that "reticulin" fibres as defined by silver impregnation do not all have an identical composition.

Clinical importance of acquired cystic disease of the kidney in patients undergoing dialysis

Abstract: From 1976 to 1982 five patients undergoing haemodialysis at Oxford Renal Unit suffered serious complications from acquired cystic disease of the kidney and two died as a direct result. Clinical features seen were pain, haematuria, palpable renal enlargement, massive haemorrhage, resolution of anaemia, and metastatic malignancy. The clinical histories emphasise the features of a disease that is likely to assume increasing importance in patients undergoing haemodialysis.

The anaemia of Plasmodium falciparum malaria.

Abstract: Anemia is an important complication of P. falciparum malaria infection. This paper describes recent studies that have attempted to define some of the pathophysiological mechanisms involved in different forms of infection and at different stages of the illness. After an acute infection there is a steady fall in the haemoglobin level with an inappropriate reticulocyte response. Current evidence indicates that this form of anaemia may result from a combination of acute sequestration of iron in the reticuloendothelial system associated with a shortened red cell survival. Recent studies indicate that there may be a dyserythropietic component as well. The mechanism for the shortened red cell survival is uncertain; although it may be due in part to sequestration of parasitized cells, the haemoglobin level continues to fall for several weeks after the acute episode and other factors must be involved. The role of immune haemolysis appears to be relatively small. It is becoming apparent that severe dyserythropoiesis with minimal haemolysis plays a major role in the anaemias of Plasmodium falciparum infection, particularly in immune individuals. This phenomenon has been studied by both light and electron microscopy and by assessing the in vitro kinetics of erythroid precursor proliferation. The results indicate a major defect in erythroid maturation with a significant degree of erythrophagocytosis. Although these studies have provided a clearer picture of the pathophysiology of anaemia at different phases of P. falciparum infection, there is still little indication of how the basic changes in red cell production and survival are mediated.

Effect of alpha thalassaemia on the rheology of homozygous sickle cell disease

Abstract: A study of rheological determinants (plasma viscosity, whole-blood viscosity, and erythrocyte deformability) was made in 24 matched pairs of patients with homozygous sickle cell disease, with and without homozygous alpha-thalassaemia 2. Patients with coexisting alpha-thalassaemia showed a significant increase in erythrocyte deformability measured as filtration of washed erythrocytes through 5 micron diameter pores and also as viscosity of whole blood at high shear rate (230s-1) and standard haematocrit (0.45). This rheological advantage may explain the beneficial effect of alpha-thalassaemia 2 on haematological parameters and clinical events in homozygous sickle cell disease.

Quantitative morphology of endocrine cells in human fetal pancreas.

Abstract: Sections of pancreas from human fetuses, 6–20 weeks gestation, were stained with immunoperoxidase for insulin (B cells), glucagon (A cells), pancreatic polypeptide or somatostatin (D cells). Morphometric analyses were performed on sections from head and tail regions of each fetus. No stained cells were found at 7 weeks. A, B, pancreatic polypeptide and D cells were found at 9 weeks in primitive islets or as isolated cells adjacent to duct cells. There was no relationship between the density of each endocrine cell type and fetal age, but there was a significant increase in the relative density (percentage total endocrine cells) of D cells from 10–20 weeks (p<0.01). The tail contained significantly more A cells (p< 0.05) and less pancreatic polypeptide cells (p<0.01) than the head but similar densities of B and D cells. Lobules containing a high density of pancreatic polypeptide cells and few A cells were found in the posterior part of the head in six fetuses, aged 10–20 weeks.