Showing papers by "John Radcliffe Hospital published in 1985"

Hypervariable 'minisatellite' regions in human DNA.

Abstract: The human genome contains many dispersed tandem-repetitive 'minisatellite' regions detected via a shared 10-15-base pair 'core' sequence similar to the generalized recombination signal (chi) of Escherichia coli. Many minisatellites are highly polymorphic due to allelic variation in repeat copy number in the minisatellite. A probe based on a tandem-repeat of the core sequence can detect many highly variable loci simultaneously and can provide an individual-specific DNA 'fingerprint' of general use in human genetic analysis.

Individual-specific 'fingerprints' of human DNA.

Abstract: Simple tandem-repetitive regions of DNA (or 'minisatellites') which are dispersed in the human genome frequently show substantial length polymorphism arising from unequal exchanges which alter the number of short tandem repeats in a minisatellite. We have shown previously that the repeat elements in a subset of human minisatellites share a common 10-15-base-pair (bp) 'core' sequence which might act as a recombination signal in the generation of these hypervariable regions. A hybridization probe consisting of the core repeated in tandem can detect many highly polymorphic minisatellites simultaneously to provide a set of genetic markers of general use in human linkage analysis. We now show that other variant (core)n probes can detect additional sets of hypervariable minisatellites to produce somatically stable DNA 'fingerprints' which are completely specific to an individual (or to his or her identical twin) and can be applied directly to problems of human identification, including parenthood testing.

A highly polymorphic DNA marker linked to adult polycystic kidney disease on chromosome 16

Abstract: Adult polycystic kidney disease (APCKD) is a common and often lethal multi-organ disease with an autosomal dominant pattern of inheritance; approximately 1 in 1,000 people carry the mutant gene1. The major pathological abnormality is the development and progressive enlargement of cysts in several organs including the liver, pancreas and spleen as well as the kidneys. The basic biochemical defect which leads to the formation of cysts remains unknown2. Cyst development, which is not retarded by any known therapy, leads to irreversible renal failure and death at a mean age of 51 unless dialysis or transplantation are used3. Patients with the disease account for 9% of chronic dialysis requirement4. The first symptoms tend to occur in the fourth decade, after most patients have reproduced3. Presymptomatic diagnosis depends on the ultrasonographic detection of cysts, but exclusion cannot be achieved by this means; 34% of at-risk patients in the second decade and 14% in the third will go on to develop cysts after negative diagnosis5. The low sensitivity of diagnostic techniques in this critical age-range imposes severe limitations on genetic counselling and the condition cannot be identified prenatally. Hence we have searched for a linkage marker for APCKD; we show here that the APCKD locus is closely linked to the α-globin locus on the short arm of chromosome 16 (ẑ = 25.85, θ=0.05).

Alloimmunisation to HLA antigens following transfusion with leucocyte-poor and purified platelet suspensions.

Abstract: 24 previously non-transfused patients were given three transfusions of 200 times 108 platelets at 14-day intervals. Group I (12 patients) received leucocyte-poor platelet suspensions with a mean contamination of 15 times 106 leucocytes per transfusion. Group II (12 patients) received platelets with <5 times 106 leucocytes per transfusion. 5 patients in group I and no patients in group II developed lymphocytotoxic antibodies (p == 0.037). Platelets with fewer than 5 times 106 leucocytes did not seem to stimulate a response to major histocompatibility antigens, but with a small contaminating dose of leucocytes appeared to be highly immunogenic.

A premutation that generates a defect at crossing over explains the inheritance of fragile X mental retardation.

Abstract: The view that the Martin-Bell syndrome (X-linked mental retardation with fragile site at Xq27/8) is inherited in a regular X-linked fashion is becoming untenable with the increasing number of reports of transmission through phenotypically normal males. Analysis of the published pedigrees containing such males shows that their heterozygous daughters are never mentally retarded, and have either no fragile site or very few indeed. By contrast, in the next generation, a third of the female heterozygotes are mentally subnormal with an average of 29% fragile sites. These data suggest a premutation that generates the definitive mutation only when transmitted by a female. We propose an inherited sub-microscopic chromosome rearrangement involving the Xq27/8 region that causes no ill effect per se, but generates a significant genetic imbalance when involved in a recombination event with the other X chromosome. This hypothesis explains many of the puzzling genetic aspects of the Martin-Bell syndrome, but it also complicates the interpretation of linkage analysis with genetic markers.

Legionella pneumophila serogroup 1 subgrouping by monoclonal antibodies--an epidemiological tool.

Abstract: A panel of 10 monoclonal antibodies was used to subgroup 326 strains of Legionella pneumophila serogroup 1. All but two strains could be classified into three major subgroups named after their representative strains Pontiac 1, Olda and Bellingham 1. Of the 50 isolates from patients, 44 representing 32 separate incidents were of the Pontiac subgroup. This subgroup was also found in 16 of 18 buildings epidemiologically associated with Legionnaires' Disease. In contrast, strains of the Olda subgroup predominated in buildings where no infections had occurred. In 9 of the 11 incidents where isolates were available from at least one patient as well as from the suspected environmental source, the monoclonal antibody reaction patterns of strains from patients were identical to those of one or more of their environmental counterparts.

Neuropeptide Y: a novel renal peptide with vasoconstrictor and natriuretic activity.

Abstract: 1. A novel vasoconstrictor peptide, neuropeptide Y (NPY), has been identified in considerable quantities in the renal artery and kidney. Within the kidney, NPY was confined to the cortex and corticomedullary interface, the regions where the juxtaglomerular apparatus is most numerous. 2. In the isolated perfused rat kidney, NPY caused a prompt dose-dependent increase in perfusion pressure and reduction in flow, with only a small fall in glomerular filtration rate (GFR). In spite of the reduced renal perfusion, a dose-dependent natriuresis was observed. This response contrasts to the response of this preparation to noradrenaline, which causes sodium reabsorption. 3. The presence of a potent vasoconstrictor and natriuretic peptide within the rat renovascular system suggests that it may play a significant role in the control of renal function.

Control of haemoglobin switching by a developmental clock

Abstract: The pattern of haemoglobin production changes at the embryonic, fetal and postnatal stages of human development, reflecting the expression of different globin genes in both the alpha-like and beta-like gene clusters. Recent studies have identified alterations in the state of DNA methylation and sensitivity to nuclease digestion associated with developmental expression of the globin genes in red blood cell precursors, but the mechanism initiating these changes remains unknown. Despite the screening of large numbers of blood samples from newborn infants, no mutants have been found which affect the timing of these changes (with one possible exception involving a chromosomal translocation), thus necessitating alternative approaches to analysing the cellular basis for the timing of haemoglobin switching. Although many mechanisms are possible, the initiation of the switch from fetal to adult haemoglobin could be regulated essentially either by a developmental clock inherent to haematopoietic stem cells or by an inductive environment, and in an attempt to distinguish between these possibilities, we have transplanted sheep fetal haematopoietic tissue into adult animals. Although previous experiments of this type produced conflicting results, the accumulated results presented here demonstrate that the pattern of haemoglobin production after transplantation is determined largely by the gestational age of the fetal donor cells.

Characterization of blast cells in chronic granulocytic leukaemia in transformation, acute myelofibrosis and undifferentiated leukaemia. II. Studies with monoclonal antibodies and terminal transferase.

Abstract: Summary A panel of 19 monoclonal antibodies (McAb) and the enzyme terminal transferase (TdT) have been applied to the characterization of poorly differentiated blasts from 50 patients with chronic granulocytic leukaemia (CGL) and myelofibrosis in blast crisis (BC), acute myelofibrosis and undifferentiated leukaemia. These cells were also extensively studied by transmission electron microscopy (TEM) (see Polli et al, 1985a). McAb against platelet glycoproteins (GP) showed a high specificity for megakaryoblasts, in particular those reactive with the GPIIb/IIIa complex (J15) and GPIIIa (C15 and C1 7), which were positive in a higher proportion of blasts than the McAb to GPIb (AN51 and FMC25). Findings with these anti-platelet McAb paralleled those of the platelet-peroxidase (PPO) reaction in 76% of cases studied simultaneously. The PPO reaction was always positive in cases in which two or more of the McAb were reactive with the blast cells. The differences observed suggest, nevertheless, that PPO is more sensitive for megakaryoblasts than the McAb and that this TEM technique should be reserved for cases which are negative with the platelet specific McAb. Of the McAb against myeloid antigens used in this series OKM1 was positive in 50% of cases but the others failed to demonstrate early features of differentiation in myeloblasts and monoblasts. In only three cases were erythroid precursors demonstrated by TEM and these were the only ones reactive with a McAb to glycophorin-A (LICR LON/R10). TdT and the McAb J5 helped in the identification of lymphoblasts which were seen as a ‘pure’proliferation in 23% of CGL-BC and as case that showed frank reactivity with FMC10, 11 and 13 in this study the blasts were mast cell precursors and this may suggest that these leukaemic cells are more mature. The greater sensitivity of OKM1 to detect granulocytic/monocytic differentiation shown here confirms the findings of van der Reijden et al (1983) in AML and of Griffin et al (1983b) in CGL-BC with a similar McAb, Mol. The demonstration of TdT and the cALL antigen by the McAb J5 showed that blast cells which may be considered undifferentiated or even myeloid on light microscopy morphology were in fact lymphoblasts. In this respect our study confirms a 20–25% incidence of pure lymphoid phenotypes in Ph1-positive CGL-BC (Janossy et al, 1980; Greaves et al, 1982; Griffin et al, 1983b). If we consider also the minor populations of lymphoblasts seen in the mixed cases, the incidence of cells with a lymphoid phenotype in CGL-BC was 40% in this series. The use of McAb against early precursor cells (RFB1, FMC8 and OKIa) did not show a particular advantage for the clarification of the cell lineage of the blasts in the cases under study, although all of them were positive in lymphoblasts. It was of interest, however, that in the mixed cases these reagents usually detected the majority of blasts whilst the lineage specific McAb were reactive with some of the cell populations. A number of mixed blast cell proliferations were demonstrated in this study. TEM analysis has been valuable for distinguishing the morphology and cytochemical markers of the distinct cell populations involved (Polli et al, 1985a). Findings with the various lineage specific McAb were very often suggestive of the presence of more than one type of blast cell (Table VII). Light microscopy studies combining the demonstration of TdT in the cell nucleus with that of an antigen in the cell membrane have allowed us to distinguish megakaryoblasts (TdT negative, AN51 positive) from lymphoblasts (TdT positive, AN51 negative).

A Multiple Injection Regimen using an Insulin Injection Pen and Pre‐filled Cartridged Soluble Human Insulin in Adolescents with Diabetes

Abstract: A multiple insulin injection regimen using a self-contained injection device Novopen (Novo Industries, Bagsvaerd, Copenhagen, Denmark) was assessed in 11 adolescents (age range 12.1-16.9 years) with diabetes. Ten patients completed the 3-month study period and eight expressed a wish to continue with the regimen, finding that the advantages it offered out-weighed the inconvenience of multiple injections. Mean glycosylated haemoglobin fell over the 3 months of the study period from 13.7 +/- 2.7% to 11.7 +/- 3.4% (NS) and there was a trend towards lower mean blood values which reached significance at the pre-lunch measurement (p less than 0.02).

The role of baroreflex sensitivity in post-exercise hypotension

Abstract: We investigated whether changes in baroreflex sensitivity could explain the drop in blood pressure after exercise in 12 borderline hypertensive subjects. Intra-arterial blood pressure and baroreflex sensitivity (phenylephrine method) were measured before and 10, 20, 40 and 60 min after maximal exercise. Systolic blood pressure was lower at all stages after exercise. Baroreflex sensitivity was reduced at 10 min, recovered at 20 min and rose above control values at 40 and 60 min. Although the baroreflex sensitivity recovers slowly after exercise, at 40 and 60 min it is higher than the control value and could therefore contribute to the sustained reduction in blood pressure after a period of heavy exercise.