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Biomedical subjects

S M Richards

Publications and source records attributed to S M Richards.

At least 73 records · Page 4Linked to original sources
PubMed1995

Multiple types of ryanodine receptor/Ca2+ release channels are expressed in vascular smooth muscle.

Functional studies on vascular smooth muscle suggest the presence of ryanodine receptors (RyRs) with differing properties. In an attempt to understand such differences we investigated, using reverse transcription-polymerase chain reaction (RT-PCR), the possibility that smooth muscle cells express multiple types of RyRs. RNA was extracted from rat aorta, superior and small mesenteric arterial vessels, purified aortic smooth muscle media, or cultured aortic smooth muscle cells for cDNA synthesis. The cDNAs encoding RyR1, RyR2, and RyR3 were amplified using PCR primers based on sequences close to the 3' coding region of the RyR genes and PCR products verified by restriction endonuclease analysis. All three members of the RyR gene family were found to be present in vascular smooth muscle. This finding of multiple types of RyRs expressed in the same cell type indicates a complex mechanism of RyR Ca2+ channel regulation involving the formation of homo- and/or heterotetrameric complexes.

Animals↗
PubMed1995

UK Medical Research Council randomised, multicentre trial of interferon-alpha n1 for chronic myeloid leukaemia: improved survival irrespective of cytogenetic response. The UK Medical Research Council's Working Parties for Therapeutic Trials in Adult Leukaemia.

Interferon-alpha may be better than cytotoxic drugs in the long-term management of patients with chronic myeloid leukaemia (CML) in chronic phase. To test this possibility 587 patients with CML in chronic phase were randomly allocated to receive lymphoblastoid cell-line interferon-alpha n1 (IFN-alpha, n = 293) or chemotherapy with busulphan or hydroxyurea (no IFN-alpha, n = 294) as maintenance after initial induction treatment with cytotoxic drugs. There was a significant survival benefit for patients in the IFN-alpha arm when analysed on the basis of intention to treat (2p = 0.0009). The median survival for those allocated IFN-alpha was 61 months and no IFN-alpha was 41 months. Out of 269 patients with Philadelphia-positive CML in the IFN-alpha arm with at least 6 months follow-up, 211 were evaluable for haematological response: 145 (68%) achieved good responses (A+ or A type), 37 (18%) had partial responses (B type) and 29 (14%) had poor responses (C type). Patients with types A and B responses had a better survival than those in the no IFN-alpha arm; patients with type C responses had survival equivalent to the no IFN-alpha arm. Of these 269 patients, 26 of whom had not started IFN-alpha, 59 (22%) achieved a significant degree of cytogenetic response but 210 (78%) did not have a response. Cytogenetic responders survived significantly longer than non-responders and even non-responders survived longer than patients in the no IFN-alpha arm. Since cytogenetic non-responders had worse than average prognostic features, they may also benefit from IFN-alpha therapy. We conclude that treatment with IFN-alpha prolongs the survival of patients with CML; benefits of IFN-alpha are not confined to cytogenetic responders but may extend to most, if not all patients receiving IFN-alpha treatment; and cytogenetic response to IFN-alpha treatment identifies patients with a relatively good prognosis.

Adult↗
PubMed1995

Intensification of treatment and survival in all children with lymphoblastic leukaemia: results of UK Medical Research Council trial UKALL X. Medical Research Council Working Party on Childhood Leukaemia.

The UK Medical Research Council trial MRC UKALL X was designed to investigate the benefit of one or two courses of additional intensification therapy in children with acute lymphoblastic leukaemia receiving standard treatment. From 1985 to 1990 1612 children, comprising more than 90% of eligible cases in the UK, were treated with intensive induction therapy, central nervous system directed therapy with cranial irradiation and intrathecal methotrexate, and continuing treatment for 2 years. 1171 children were randomised to receive additional intensification therapy at 5 weeks, 20 weeks, both, or neither. At follow-up of at least 3 years disease-free survival for all children at 5 years was 62% (95% confidence interval [Cl] 60.0-64.4), a significant improvement over the 56% (53.0-59.6) found in the preceding MRC UKALL trial. The 5-year disease-free survival was 71% (65.5-76.1) for children randomised to two blocks of intensification therapy, this being significantly better than the 62% (56.6-68.0), 61% (55.7-67.1), and 57% (50.9-62.7) rates for the groups randomised to one intensification block at 5 weeks, one at 20 weeks, and no intensification, respectively. The benefits of intensification therapy were seen irrespective of clinical factors known to influence outcome such as age, sex, and initial leucocyte count. We conclude that the addition of two courses of intensification therapy has produced a 14% improvement in disease-free survival and an 11% improvement in overall survival for the randomised patients. This additional treatment is of benefit to all children with acute lymphoblastic leukaemia, even those traditionally deemed at lower risk of relapse.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1995

Differing protection with aspartate and glutamate cardioplegia in the isolated rat heart.

Aspartate and glutamate each have been shown to improve cardiac recovery after hypoxia or ischemia under normothermic conditions, but whether their effects are additive and to what extent they are modified by hypothermia has not been studied systematically. We set out to compare the individual and combined protective effects of aspartate and glutamate during cardioplegic arrest under normothermic and hypothermic conditions in the rat. Using isolated working rat hearts, functional and metabolic recovery was assessed after 0.5 hours of potassium arrest at 37 degrees C or 5 hours at 2 degrees C in control hearts (C) and in hearts in which 20 mmol/L glutamate (G), 20 mmol/L aspartate (A), or both (A + G) was added to the cardioplegic solution. Under normothermic conditions, percentage recovery of prearrest work (mean +/- standard error of the mean) was as follows: C = 31.7 +/- 2.8, G = 34.8 +/- 0.2, A = 49.6 +/- 2.8*, A + G = 53.7 +/- 2.3*. Under hypothermic conditions, the values were as follows: C = 40.4 +/- 4.0, G = 45.2 +/- 2.3, A = 59.4 +/- 1.8*, A + G = 54.1 +/- 1.2* (*p < 0.01 versus C and G). Recovery of postischemic high-energy phosphate content followed the same pattern: A = A + G > G or C. Measurement of postischemic myocardial content of amino acids showed that recovery of function and energy status correlated with maintenance of myocardial levels of aspartate (r = 0.9; p < 0.01) but not glutamate.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenine Nucleotides↗
PubMed1995

Meta-analyses and overviews of randomised trials.

The number of meta-analyses or overviews appearing in the literature is rapidly increasing. Because of the problems inherent in non-randomised studies, which are not diminished by using meta-analysis techniques, this paper only refers to meta-analyses of randomised trials. Examples are given of the value of meta-analyses of randomised trials in many different circumstances and the different methods that have been used are discussed. The most reliable type of meta-analysis uses individual patient data and includes all trials fitting the pre-defined criteria, published and unpublished. As with a single randomised trial, large numbers of randomised patients are needed to give reliable results. Well-conducted meta-analyses or overviews are the best method of summarising all available unbiased evidence on the relative effects of treatments.

Humans↗
PubMed1995

A technique for accurate use of CD4+ cell counts.

Despite uncertainty over their reliability, CD4+ cell counts are used extensively in both clinical and research settings to document progression in HIV infection. We examined, therefore, whether the performance of a simple statistical test would facilitate greater accuracy in the use of this marker. CD4+ cell count data were collected from a cohort of deceased (N = 60) and living HIV-positive gay men (N = 100). Pearson's product moment correlation coefficients were calculated for each individual in order to examine the association between CD4+ counts and time since diagnosis. Correlations of 0.7 or greater were obtained in approximately 50 percent of cases in each cohort. For these individuals, CD4+ cell counts were deemed to be a reliable indicator of rate of progression. The results suggest that the proposed technique ensures greater precision in the use of CD4+ cell counts and that the technique cna be used in individuals with either complete (deceased patients) or partial (living patients) CD4+ data.

CD4 Lymphocyte Count↗
PubMed1995

Gender and treatment outcome in childhood lymphoblastic leukaemia: report from the MRC UKALL trials.

We have examined the factors influencing prognosis in over 4000 children with acute lymphoblastic leukaemia (ALL) aged 1-14 who have been treated on consecutive MRC UKALL trials from 1972 to 1990. During this time the results of treatment have improved steadily but are consistently superior in girls when compared with boys; the 5-year event-free survival in girls improving from 51% to 71% and in boys from 31% to 57%. These results were independent of age and presenting leucocyte count. Boys not only had a testicular relapse rate of 10% but an excess of bone marrow relapse, particularly evident after 2 years from diagnosis. Other prognostic factors included organomegaly and the morphology of leukaemic blast cells; immunophenotype of the leukaemia, however, had no independent significance after allowance for age, sex and leucocyte count. The influence of sex on prognosis was reaffirmed when we examined various methods of identifying children at highest risk of treatment failure for whom alternative therapy such as bone marrow transplantation might be justified. In MRC UKALL X children had been deemed 'high risk' on the basis of leucocyte count alone, but with further follow-up it has become apparent that girls with an initial leucocyte count of > 100 x 10(9)/l have a similar prognosis to boys with a lower count. We therefore derived a risk score based on sex, age and count which has given better discrimination between standard risk (66% 5-year survival) and poor risk (39%) survival than other methods. This group of worse-risk children includes 16% of boys but only 3% of all girls. Gender remains an important prognostic factor in UKALL trials and there are very few girls who are at highest risk of treatment failure. The reasons for this remain unclear, but the pattern of relapses suggests that boys more often get inadequate systemic therapy. We postulate that the reasons for treatment failure may relate to sensitivity to continuing (maintenance) chemotherapy.

Adolescent↗
PubMed1995

Infection of a human respiratory epithelial cell line with rhinovirus. Induction of cytokine release and modulation of susceptibility to infection by cytokine exposure.

Rhinovirus infections cause over one third of all colds and are a contributing factor to exacerbations of asthma. To gain insights into the early biochemical events that occur in infected epithelial cells, we develop, for the first time, a model in which a pure respiratory epithelial cell population can be routinely infected by rhinovirus. Viral infection was confirmed by demonstrating that viral titers of supernatants and lysates from infected cell increased with time and by PCR. Infection by rhinovirus 14 was inhibited by homotypic antiserum and by antibodies to intercellular adhesion molecule-1 (ICAM-1), the receptor for this virus. Susceptibility of epithelial cells to infection by rhinovirus 14 (but not rhinovirus 2, an ICAM-1 independent strain) can be increased by preexposure of cells to TNF alpha, whereas IFN gamma reduces susceptibility to infection by both rhinovirus strains. Rhinovirus infection per se does not markedly alter ICAM-1 expression on epithelial cells. Finally, we demonstrate that rhinovirus infection induced increased production of IL-8, IL-6, and GM-CSF from epithelial cells. Production of IL-8 correlated with viral replication during the first 24 h after infection. This model should provide useful insights into the pathogenesis of rhinovirus infections.

Base Sequence↗
PubMed1995

Studies on the microheterogeneity and in vitro activity of glycosylated and nonglycosylated recombinant human prolactin separated using a novel purification process.

Recombinant human PRL was produced in a murine C127 cell expression system and purified to greater than 97% homogeneity using anion and cation exchange chromatography. This material was biologically equivalent to pituitary-derived PRL in both an enzyme-linked immunosorbent assay and the Nb2 lymphoma cell proliferation assay. The predominant PRL forms were identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting as being 23 and 25 kilodaltons (kDa). These mass values were confirmed by electrospray mass spectroscopy. Glycosidase digestions indicated that the 25-kDa PRL is N-glycosylated and sialylated, whereas 23-kDa PRL is nonglycosylated. Glycosylated and nonglycosylated forms of the hormone were individually purified to greater than 95% homogeneity using novel cation exchange chromatography. Isoelectric focusing demonstrated that both forms consist of multiple charge isomers, with the charge heterogeneity of the glycosylated form primarily due to differences in sialylation. Monosaccharide analysis of the glycosylated form suggested a minimal complex oligosaccharide chain that may be fucosylated and partially sialylated. Oligosaccharide mol wt were determined by electrospray ionization mass spectroscopy. Analysis of the oligosaccharides by fluorophore-assisted carbohydrate electrophoresis indicated that bi- and triantennary oligosaccharide forms are predominant and have multiple combinations of terminal sialylation. Both forms of PRL were active in the Nb2 lymphoma cell proliferation assay; however, the 23-kDa nonglycosylated form was 3-4 times more active in this assay than the 25-kDa glycosylated form.

Amino Acid Sequence↗
PubMed1994

Vasoconstrictor-mediated release of purines and pyrimidines from perfused rat hindlimb, perfused mesenteric arcade and incubated de-endothelialized aorta.

1. Reperfusion of hindlimbs that had previously been exposed to either 10 or 60 min global ischaemia resulted in transient washouts of uracil and uric acid in approximate proportion to the interval of ischaemia. However, changing the interval of sequential angiotensin II infusions from 10 to 60 min did not affect the magnitude of sustained uracil and uric acid release. 2. Perfused rat mesenteric artery arcade released uracil and uric acid and each was further increased approximately 2-fold by exposure to the vasoconstrictor, serotonin (6.7 microM). 3. Incubated de-endothelialized rat aorta also released purines and pyrimidines and this was increased further when subjected to increased work loads. 4. The increased rates of release of purines and pyrimidines from hindlimb, and the simpler vascular preparations of mesenteric arcade and aorta, were in proportion to the relative rates of increase in oxygen consumption under maximum vascular load. 5. It is concluded that the release of purine and pyrimidine nucleosides and their catabolites from perfused rat hindlimb occurring as a consequence of vasoconstriction is not the result of release from previously ischaemic tissue. In addition, release of purines and pyrimidines appears to be a general feature of vascular smooth muscle subjected to high workloads.

Analysis of Variance↗
PubMed1994

A second course of treatment for childhood acute lymphoblastic leukaemia: long-term follow-up is needed to assess results.

We report the results of long-term follow-up of 94 children who completed treatment for acute lymphoblastic leukaemia (ALL) between 1974 and 1986 and subsequently experienced a bone marrow relapse before 1992. 91 children received further induction, intensification and CNS directed therapy; 19 proceeded to BMT or ABMT and the remainder were treated on one of three protocols which increased in intensity. The duration of second remission improved significantly with increasing intensity of treatment and bone marrow transplantation was followed by fewer relapses than chemotherapy. Analysis of factors influencing the duration of second remission showed that only length of first remission was of additional significance; the median duration of second remission being only 19 months in children with a first remission of less than 4 years and 62 months in those with longer first remissions. 29 children electively stopped chemotherapy a second time but only 11 of these remain still in second remission with recurrences occurring for up to 7 years from the the time first relapse. Only three of the 24 long-term survivors had no significant late effects of treatment; these were most marked in children who had received a second course of radiotherapy. We conclude that very long follow-up is necessary to determine whether patients may be successfully re-treated following late bone marrow relapse and that all such treatment is associated with a high incidence of late effects.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1994

Periodic acid Schiff reaction in childhood lymphoblastic leukaemia. The Medical Research Council Working Party on Childhood Leukaemia.

AIMS: To assess the prevalence and degree of periodic acid Schiff (PAS) positivity in blast cells from children with lymphoblastic leukaemia (ALL); its association with other disease characteristics; and its clinical importance in predicting the outcome of treatment. METHODS: Marrow slides from entrants to a large United Kingdom multicentre ALL trial (UKALL X) were batch processed and assessed blind for PAS positivity by one morphologist. Patients were classified into groups A, B, and C, corresponding to less than 1% PAS positive cells, 1-10%, and over 10%, respectively. Their PAS pattern was then compared with other clinical and pathological features of ALL and with treatment outcome. RESULTS: Slides from 921 children were examined of which 371 (40%) were categorised as group A, 324 (35%) as group B, and 226 (25%) as group C. There was a clear association between the presence of blast cell vacuoles on Romanowsky staining and PAS positivity. Group A (PAS negative) patients included a disproportionate excess of those with L2 morphology, those under 2 or over 6 years of age, those with an initial white cell count over 50 x 10(9)/l, those with a T or null cell immunophenotype, and those with chromosomal abnormalities other than "high hyperdiploidy". Four years from diagnosis, group C patients had an 8% disease free survival advantage over those in group A (2p = 0.01). This was irrespective of initial white cell count, but not of immunophenotype or the presence of vacuoles. CONCLUSIONS: Strong PAS positivity is a feature of "common" ALL and is particularly associated with blast cell vacuoles. It does occasionally occur in other disease subtypes with or without vacuoles. It predicts a better response to current treatment, but not independently of other cell characteristics.

Adolescent↗
PubMed1994

Characterization of perfused periaortic brown adipose tissue from the rat.

A technique was developed for the perfusion of periaortic brown adipose tissue (BAT) with a view to assessing vascular system involvement in BAT thermogenesis. The procedure involved cannulation of the thoracic aorta and ligation of the intercostal branches and the distal thoracic aorta. Perfusion was conducted in a buffer-filled chamber using constant flow at 37 degrees C. Lactate dehydrogenase leakage was less than 2%/h, and after 30 min of perfusion the energy charge was 0.72 +/- 0.05 (n = 4) and differed little from freshly sampled interscapular BAT (0.71 +/- 0.03 (n = 7)). Periaortic BAT was indistinguishable from interscapular BAT in enzyme content, mitochondrial size, mitochondrial cristae, lipid content, and cell size. Basal oxygen consumption (VO2) was 64.3 +/- 7.4 mumol.h-1.g-1 wet weight, and basal perfusion pressure was 65 +/- 3 mmHg (1 mmHg = 133.3 Pa). Norepinephrine and isoproterenol each increased VO2 of perfused periaortic BAT in a time-dependent and reversible manner. Half-maximal stimulation of VO2 occurred at 12 nM norepinephrine and 8 nM isoproterenol; maximally stimulated tissue had a VO2 of approximately 150 mumol.h-1.g-1 wet weight. Norepinephrine (50 nM) had no consistent effect on perfusion pressure, but the increase in VO2 by this agonist was completely blocked by 10 microM DL-propranolol and unaffected by phentolamine (1-20 microM) or nitroprusside (0.01-1 mM). Increasing the perfusion flow rate increased pressure and had no effect on basal VO2 but increased the VO2 response due to norepinephrine.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue, Brown↗
PubMed1994

Acute lymphoblastic leukaemia in infancy: experience in MRC UKALL trials. Report from the Medical Research Council Working Party on Childhood Leukaemia.

Acute lymphoblastic leukaemia (ALL) is rare under 1 year and has a poor prognosis. Only 14 of 48 infants treated on two consecutive MRC UKALL trials remain alive in first remission. Forty infants have subsequently been treated on a protocol incorporating further intensification with an option for high-dose chemotherapy and autologous or allogeneic bone marrow transplantation. The results show no improvement over previous trials largely due to the number of remission deaths; four of nine being associated with toxicity of 5 days of etoposide and cytarabine. Only three of 11 children treated by high-dose chemotherapy and transplantation remain alive in remission. Multivariate analysis of the factors influencing prognosis in all 88 infants showed that only age was significant. Event-free survival was 40% at 5 years for children over 26 weeks but under 10% for younger children. These results show the susceptibility of infants to the toxicity of intensive chemotherapy and do not support the use of short term high-dose chemotherapy alone in the management of infant leukaemia. Despite the unique biological features of infant ALL it appears that these patients also may benefit from longer courses of treatment with a maintenance (continuing) phase.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1993

Antibody response in patients with Gaucher disease after repeated infusion with macrophage-targeted glucocerebrosidase.

Recent clinical data have shown that enzyme replacement therapy with macrophage-targeted glucocerebrosidase (GCR) can be effective in treating type 1 Gaucher disease. Sera from 262 patients, repeatedly infused with GCR, were assessed for the presence of antibodies to this therapeutic protein. Patient serum samples obtained at 3-month intervals were assessed by enzyme-linked immunosorbent assay and those with values greater than two standard deviations above the mean value obtained with a pool of normal human sera were further characterized by radioimmunoprecipitation. At the time of these analyses, the duration of patient treatment varied from 3 months to approximately 3 years. Of the 262 patients analyzed, 34 (12.9%) showed IgG antibodies, as confirmed by radioimmunoprecipitation. All patients who seroconverted did so within 1 year of treatment. The predominant antibody developed was the IgG1 subclass. Fourteen patients in the study experienced periodic symptoms suggestive of immediate hypersensitivity. Nine of these 14 patients had antibody to GCR as determined by radioimmunoprecipitation, whereas 5 patients were antibody negative. There was no evidence of the development of IgE antibodies in these 14 patients. The presence of GCR antibodies did not appear to effect efficacy of therapy in any of the patients treated to date.

Antibodies↗
PubMed1993

[32P]phosphate autoradiography as an indicator of regional myocardial oxygen consumption?

The present study was undertaken to assess whether [32P]uptake and autoradiography could be used as an indicator of regional myocardial oxygen consumption. Rat hearts were perfused in the Langendorff mode with medium containing [32P]orthophosphate (32Pi) and the incorporation of label into ATP, perchloric acid-insoluble and soluble material and total tissue was determined. Oxygen uptake and perfusion pressure were continuously monitored. For control hearts the rate of incorporation of radioactivity into all four fractions was linear. Isoproterenol and pressure loading each increased total 32Pi uptake rate and the incorporation rate of 32Pi into ATP. Significant positive correlations were noted between the rates of total 32Pi uptake and oxygen uptake (r = 0.895; P < 0.001) and between the rates of 32P incorporation into ATP and oxygen uptake (r = 0.890; P < 0.001). Autoradiography of diffusible radioactive material (representing total 32Pi uptake) indicated that label correlated with oxygen uptake (r = 0.850; P < 0.001) and was distributed uniformly across the ventricle wall. Hearts subjected to 30 min of regional ischemia followed by reperfusion were indistinguishable from the control group in terms of either total 32Pi uptake or total oxygen uptake, but showed a marked necrotic area that was unlabeled surrounded by an area that was intensely labeled. It is concluded that autoradiography of diffusible radioactive material representing total 32Pi uptake may be applicable for assessing regional myocardial oxygen uptake. The technique has identified a region of tissue in reperfused ischemic hearts that surrounds necrotic tissue and which may have a compensatory increase in a oxidative metabolism.

Animals↗
PubMed1993

Results of Medical Research Council trial UKALL IX in acute lymphoblastic leukaemia in adults: report from the Medical Research Council Working Party on Adult Leukaemia.

The MRC UKALL IX trial for patients with untreated ALL aged 14 years and over was open to new patients from July 1980 to April 1985. 266 patients were randomized between two induction schedules. M (involving intermediate dose methotrexate with folinic acid rescue) and D (involving daunorubicin). Schedule M resembled that used in the previous MRC adult ALL trial (UKALL VI), while schedule D was somewhat more intensive. No difference in disease-free survival was found between the treatment arms, but patients on the daunorubicin arm went into remission earlier. The overall remission rate was 87%, which is at least as good as in contemporary studies elsewhere; factors predictive of a lower remission rate were older age and higher WBC. For those who entered remission. WBC, age and sex were the most important prognostic factors. Time to achieve remission was not a significant factor after allowance was made for these. An historical comparison does not show any improvement over the preceding MRC adult trial, although the subsequent trial does show a modest improvement at present. Because the improved outlook seen in children is not apparent in adults, and no other randomized trial has demonstrated substantial benefit for any particular regimen, the next trial, UKALL XII, will be investigating the benefit or otherwise of bone marrow transplantation.

Adolescent↗