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G Blundell

Publications and source records attributed to G Blundell.

At least 19 recordsLinked to original sources
PubMed2001

Multiple pathways in the trafficking and assembly of connexin 26, 32 and 43 into gap junction intercellular communication channels.

The assembly of gap junctions was investigated in mammalian cells expressing connexin (Cx) 26, 32 and 43 fused to green, yellow or cyan fluorescent proteins (GFP, YFP, CFP). Targeting of Cx32-CFP and 43-GFP to gap junctions and gap junctional communication was inhibited in cells treated with Brefeldin A, a drug that disassembles the Golgi. However gap junctions constructed of Cx26-GFP were only minimally affected by Brefeldin A. Nocodazole, a microtubule disruptor, had little effect on the assembly of Cx43-GFP gap junctions, but perturbed assembly of Cx26-GFP gap junctions. Co-expression of Cx26-YFP and Cx32-CFP in cells treated with Brefeldin A resulted in assembly of gap junctions constructed of Cx26-YFP. Two amino acids that distinguish Cx26 from Cx32 in transmembrane domains were mutated in Cx32 to investigate underlying mechanisms determining trafficking routes to gap junctions. One mutation, Cx32I28L, conferred on it partial Cx26-like trafficking properties as well the post-translational membrane insertion characteristics of Cx26, suggesting that a key determinant regulating trafficking was present in the first transmembrane domain. The results provide a protein trafficking basis for specifying and regulating connexin composition of gap junctions and thus selectivity of intercellular signaling, with Cx32 and 43 trafficking through the secretory pathway and Cx26 also following an alternative pathway.

Animals↗
PubMed1999

Clinical follow-up of high mid-trimester maternal serum intact human chorionic gonadotrophin concentrations in singleton pregnancies.

Mid-trimester biochemical screening of 38 143 pregnancies in south-east Scotland revealed 127 cases (0.34 per cent) in which the maternal serum (MS) intact human chorionic gonadotrophin (hCG) concentration was > or = 4 multiples of the median in singleton pregnancies (MOM). Three were lost to follow-up but in 72 (58 per cent) complications developed or there were associated fetal abnormalities. This percentage was greatest at very high hCG concentrations, 92 per cent with hCG > or = 10 MOM (n = 12) compared with 48 per cent with hCG concentrations of 4-4.99 MOM (n=69). 22 cases had an MS alpha-fetoprotein > or = 2 MOM in addition to an MS hCG > or = 4 MOM, and in only 3 of these was the pregnancy uneventful; 86 per cent were associated with abnormalities or pregnancy complications.

Chorionic Gonadotropin↗
PubMed1997

Detecting familial defective apolipoprotein B-100: three molecular scanning methods compared.

Familial defective apolipoprotein (apo) B-100 (FDB), a condition that may give rise to hypercholesterolemia, is caused by mutations around codon 3500 of the apo B gene. We have compared the ability of three molecular-scanning techniques, heteroduplex analysis, single-strand conformation polymorphism (SSCP) analysis, and denaturing gradient gel electrophoresis (DGGE), to detect these mutations in a cohort of 432 hypercholesterolemic individuals. Heteroduplex analysis and DGGE detected 11 individuals with apo B mutations, 9 of whom were heterozygous for apo B R3500Q and 2 who were heterozygous for apo B R3531C. Whereas DGGE was able to distinguish between these two mutations, heteroduplex analysis was technically simpler and gave a higher sample throughput. In contrast, SSCP analysis detected only 7 of the R3500Q and none of the R3531C heterozygotes and was the most complex of the three techniques. We believe heteroduplex analysis to be the method of choice for screening large numbers of samples for FDB.

Apolipoprotein B-100↗
PubMed1996

Homocysteine mediated endothelial cell toxicity and its amelioration.

In response to homocysteine induced toxicity in human umbilical vein endothelial cells, minimal changes in the concentration of cellular protein thiols but substantial changes in the concentration of intracellular soluble thiols were observed. The latter correlated closely with changes in cellular glutathione levels. No correlation existed between cellular glutathione levels and cell viability, whereas a close correlation between NAD+ levels and cell viability was demonstrated. Large decreases in cellular NAD+ occurred in response to homocysteine induced toxicity which were accompanied by the production of single stranded DNA. 3-Aminobenzamide, an inhibitor of poly (ADP-ribose) polymerase preserved cell viability and cellular NAD+ levels. Evidence that DNA synthesis was also compromised was revealed by the decreased capacity of homocysteine treated cells to incorporate deoxyuridine. Radical scavengers were also effective in preventing homocysteine induced toxicity. It is likely that the major threat to cells derives from radicals generated intracellularly. Eicosanoid metabolism and the xanthine oxidase system have been identified as two potential sources of radicals.

Benzamides↗
PubMed1996

Second trimester screening for Down's syndrome using maternal serum dimeric inhibin A.

BACKGROUND AND OBJECTIVE: Prenatal maternal serum screening for Down's syndrome has become an important and established part of modern antenatal care. Previously it has been reported that non-specific immunoreactive inhibin may be useful in this context. Using a novel assay we have evaluated dimeric inhibin A as a possible second trimester marker of Down's syndrome. METHODS: From 1992-1993 records, stored sera from women with Down's affected pregnancies and chromosomally normal control pregnancies were identified and retrieved for analysis. These sera had been prospectively collected at 15, 16 and 17 weeks gestation. SUBJECTS: Records revealed 21 women who had had a Down's syndrome pregnancy and who also had serum available for analysis. Sera from 150 chromosomally normal controls, matched for gestation and duration of storage, were also retrieved. MEASUREMENTS: Dimeric inhibin A was measured using a recently developed two-site enzyme-linked immunoassay. This employs a capture anti inhibin beta A-subunit monoclonal antibody, covalently bound to a microtitre plate and a second anti inhibin alpha-subunit antibody conjugated to alkaline phosphatase, allowing detection. RESULTS: The mean (95% CI) maternal serum dimeric inhibin A in the samples from control pregnancies was 237 (201.5-273.4) ng/l, 266.9 (235.4-298.5) ng/l and 207.2 (178.5-235.9) ng/l at 15, 16 and 17 weeks gestation respectively. Expressing the results from the Down's samples as multiples of the normal median (MoM), the median (95% CI) MoM was 2.6 (2.25-3.57), significantly higher than the controls (P < 0.0001, Mann-Whitney U-test). In the sample set tested, for a given false positive rate of 5.3% inhibin A alone afforded a detection rate of 62%, detecting cases previously undetected by routine screening. CONCLUSIONS: Dimeric inhibin A appears to be a promising new marker for the prenatal detection of Down's syndrome. Further prospective evaluation and assessment with other established markers would now be merited.

Adult↗
PubMed1996

Familial defective apolipoprotein B-100: a study of patients from lipid clinics in Scotland and Wales.

Familial defective apolipoprotein (apo) B-100 (FDB) is an autosomal codominant disorder, which may be associated with hypercholesterolaemia. The defect is caused by the substitution of glutamine for arginine at amino acid residue 3500 of apo B-100. A total of 357 hypercholesterolaemic patients, 48 with a clinical diagnosis of familial hypercholesterolaemia attending lipid clinics in Scotland and Wales, were screened for the presence of FDB. Seven unrelated individuals, five of whom had a family history of coronary heart disease, and a further 11 first-degree relatives, were shown to be heterozygous for the mutation. Pedigree analysis demonstrated the mutation to be present on a single haplotype, suggesting that in Britain it is inherited from a common ancestor. Treatment of 11 heterozygous individuals with lipid-lowering medication showed falls in total and low density lipoprotein cholesterol ranging from 11.6 to 38.8% and 5.3 to 49.5%, respectively. In view of the condition's association with coronary heart disease and hypercholester-olaemia, it may be worthwhile identifying carriers attending lipid clinics, so that affected siblings can be offered cholesterol-lowering treatment where necessary.

Adult↗
PubMed1993

Alpha-1-proteinase inhibitor and pulmonary haemorrhage in systemic vasculitis.

Alpha-1-proteinase inhibitor phenotypes and levels were examined in 40 antineutrophil cytoplasmic antibody positive cases of systemic vasculitis. An excess of PiZ and PiS alleles were associated with the development of pulmonary haemorrhage and alpha-1-proteinase inhibitor levels were lower in the subgroup with pulmonary haemorrhage. However, this allelic imbalance and reduced alpha-1-proteinase inhibitor level was not confined to antiproteinase 3 positive patients and did not appear to be associated with other organ involvement or disease severity.

Alleles↗
PubMed1993

Rare apolipoprotein E variant identified in a patient with type III hyperlipidaemia.

We report a rare apolipoprotein E variant in an Irish female with Type III hyperlipidaemia who has the phenotype E2E1 as determined by isoelectric focusing. Sequence analysis of the apolipoprotein E gene from the proband and from four other family members, using DNA amplified by the polymerase chain reaction, demonstrated the presence of a point mutation in the common epsilon 2 allele with a G-->A transition at nucleotide 3791. This was confirmed by digestion with the restriction endonuclease TaqI, which cuts at a new site within the apolipoprotein E gene, created by the base change. This mutation results in a substitution of aspartic acid for glycine at position 127 of the mature protein. We believe this to be the first description of this apolipoprotein E variant in a family from the British Isles. The mutation appears to be 'recessive' with respect to the expression of Type III hyperlipidaemia, although it may be somewhat more potent in this regard than the parent epsilon 2 allele. The Type III hyperlipidaemia is responsive to treatment with diet and gemfibrozil.

Adult↗
PubMed1992

High dose inhaled steroid therapy and the cortisol stress response to acute severe asthma.

Systemic absorption of inhaled corticosteroids taken in high doses (> or = 1500 micrograms beclomethasone dipropionate or budesonide daily), may cause suppression of the hypothalamo-pituitary-adrenal axis. Patients taking long-term high dose inhaled steroid therapy might therefore be at risk of adrenal crisis at times of stress. Plasma cortisol levels were measured in 24 adults with severe acute asthma who had not received treatment with systemic corticosteroids prior to hospital attendance. Seven were not taking inhaled steroids, four were taking 600-1200 micrograms and 13 were taking 1500-2400 micrograms beclomethasone dipropionate or budesonide daily. Plasma cortisol levels in these 13 (median 594 nmol l-1, interquartile range 399-620 nmol l-1) were similar to levels in those taking lower dose/no inhaled steroids (median 512 nmol l-1, interquartile range 287-1050 nmol l-1): there was no relationship between inhaled steroid dose and cortisol level. Nine of the 24 patients failed to achieve plasma cortisol values > 500 nmol l-1 (the normal response to an insulin stress test). When compared with the remaining 15, they had less severe asthma as indicated by higher arterial oxygen tension (P < 0.01) and peak expiratory flow (P < 0.03). Patients taking long-term high dose inhaled corticosteroids appear to be able to mount an appropriate adrenocortical response to the stress of severe acute asthma.

Acute Disease↗
PubMed1991

Hypothalamo-pituitary-adrenal axis suppression in asthmatics inhaling high dose corticosteroids.

The frequency of hypothalamo-pituitary-adrenal (HPA) axis suppression in asthmatics taking high dose (greater than 1000 micrograms daily) inhaled corticosteroids is unknown. HPA function was studied in 78 adult asthmatics taking long-term inhaled corticosteroids (median dose 1600 micrograms, range 1200-2650 micrograms daily). All patients except one were using metered dose aerosols; 15 were using large volume spacer devices. Median duration of high dose therapy was 13 months (range 1-54). Sixty-nine patients were taking beclomethasone dipropionate (1500 micrograms, n = 36; 2000 micrograms, n = 26, greater than 2000 micrograms, n = 7) and nine budesonide (1200 micrograms, n = 2; 1600 micrograms, n = 6; 1800 micrograms, n = 1). Four patients, all of whom were taking greater than 2000 micrograms beclomethasone dipropionate, were taking 200-400 micrograms of their total dose intranasally. Twenty-six patients had discontinued long term systemic corticosteroid treatment (at least 5 mg prednisolone daily, or equivalent, for a minimum of 6 months) between 7 months and 22 years prior to assessment. All patients had measurements of 9 am serum cortisol and 24-h urine free cortisol excretion and a short tetracosactrin test. Subnormal results were: 9 am cortisol less than 190 nmol l-1; rise in serum cortisol in response to tetracosactrin less than 200 nmol l-1 and/or achieved cortisol less than 500 nmol l-1; urine free cortisol less than 80 nmol 24 h-1. Hypothalamo-pituitary-adrenal suppression was defined as subnormal results in at least two of the three tests. Tests were performed at least 2 weeks after completion of any short course prednisolone treatments. Suppression was found in 16 (20.5%) patients (1500 micrograms, n = 6; 1600 micrograms, n = 1; 2000 micrograms, n = 7; 2400 micrograms, n = 2). Risk factors identified for this suppression were: (a) previous requirement for long-term systemic corticosteroids (10/26, chi 2 = 6.1, P less than 0.02); and (b) increasing duration of high dose inhaled therapy (median 28.5 months in suppressed vs. 12 months in normal, P less than 0.05). No clear relationship was identified between HPA function and dose, even when corrected for body surface area and there was no relationship between suppression and number of short courses of prednisolone in the preceding 12 months. Screening tests of HPA function should be performed in all asthmatics taking greater than or equal to 1500 micrograms inhaled corticosteroid daily. Unless function has been shown to be normal, all patients taking these doses should carry steroid cards.

Administration, Intranasal↗
PubMed1991

Screening for hypothalamo-pituitary-adrenal axis suppression in asthmatics taking high dose inhaled corticosteroids.

High dose inhaled corticosteroids may cause suppression of the hypothalamo-pituitary-adrenal (HPA) axis. Several tests are available to screen for this suppression but it is not clear which is the most useful. HPA function was assessed in 78 adult asthmatics inhaling long-term, high dose (median 1600 micrograms; range 1200-2650 micrograms) beclomethasone dipropionate (n = 69) or budesonide (n = 9). Screening tests performed in all patients were 9 am serum cortisol, short tetracosactrin test and 24-h urine free cortisol excretion. Eleven patients also underwent insulin stress tests. Subnormal results were: 9 am cortisol less than 190 nmol l-1; urine free cortisol less than 80 nmol 24 h-1; rise in cortisol in response to tetracosactrin or hypoglycaemia less than 200 nmol l-1 and/or achieved cortisol less than 500 nmol l-1. HPA suppression (defined as subnormal results of at least two of the three initial tests and/or subnormal response to hypoglycaemia), was found in 16 patients. In the 11 patients who underwent insulin stress tests, results of all initial tests were normal in three, one test was abnormal in three and two tests were abnormal in four patients. All three tests were abnormal in the remaining patient. The response to hypoglycaemia was normal in the three patients whose screening tests were all normal; HPA suppression was present in seven patients and one patient had a borderline result. Close correlation was observed between the maximum cortisol during hypoglycaemia and both urine free cortisol (rs = 0.84; P = 0.001) and post-tetracosactrin cortisol (r = 0.75; P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Inhalation↗
PubMed1990

Do large volume spacer devices reduce the systemic effects of high dose inhaled corticosteroids?

When used in high doses, inhaled corticosteroids may cause suppression of the hypothalamo-pituitary-adrenal axis. The influence of the mode of drug inhalation on the degree of this suppression is not clear. Hypothalamo-pituitary-adrenal function was assessed by measurement of 0900 h serum cortisol concentrations, a short tetracosactrin test, and 24 hour urine free cortisol excretion in 48 adults with asthma taking 1500-2500 micrograms beclomethasone dipropionate daily via a metered dose aerosol. Twelve patients had hypothalamo-pituitary-adrenal suppression, as judged by subnormal results from at least two of the three tests or (in one patient) by an abnormal insulin stress test response. These patients then changed to inhaling the same dose of beclomethasone dipropionate through a 750 ml spacer device (Volumatic). The endocrine tests were repeated from nine days to eight weeks later in 10 patients. Comparison with initial values showed that adding the spacing device caused an increase in the median 0900 h cortisol concentration from 126 nmol/l to 398 nmol/l, in the post-tetracosactrin cortisol concentration from 402 nmol/l to 613 nmol/l and in 24 hour urine free cortisol excretion from 54 nmol to 84 nmol. The rise in serum cortisol concentration in response to tetracosactrin did not change. Evidence of persisting hypothalamo-pituitary-adrenal axis suppression was present in only four of the 10 patients; the most pronounced improvements in function tended to occur in those who had never required long term oral corticosteroids. The results from this uncontrolled study suggest that asthmatic patients taking high dose beclomethasone dipropionate may minimise adverse effects by using a large volume spacer device.

Administration, Inhalation↗
PubMed1989

Soil particles in the tissues of the foot in endemic elephantiasis of the lower legs.

The presence of microparticles of clay is demonstrated in the dermis of the foot in a patient with endemic elephantiasis. The particles are seen to be in the phagosomes of macrophages or in the cytoplasm of other cells. The conducting lymphatic in the subdermal tissue is found to be impermeable to Patent Blue Violet dye and to be fibrosed. The failure to conduct lymph to the node produces a permanent deposit of silica in the dermal tissues; a parallel is drawn with similar deposits in the lung in pneumoconiosis.

Adult↗
PubMed1985

Emphysema, cirrhosis, and heart block in a young patient with partial alpha 1 antitrypsin deficiency (PiMZ phenotype).

Severe lung disease and liver disease are not recognised features of the PiMZ phenotype, which is associated with alpha 1 antitrypsin deficiency. A 31 year old woman with this phenotype was found to have emphysema and complete heart block and showed evidence of hepatic cirrhosis, although her three sisters, all of whom had the same phenotype, were clinically normal. This case supports the possibility of a causal relation between the PiMZ phenotype and chronic lung and liver disease, but an association between alpha 1 antitrypsin deficiency and complete heart block could not be proved in this patient.

Adult↗
PubMed1984

Alpha 1 antitrypsin and lung function in British coalminers.

Alpha 1 antitrypsin (alpha 1 AT) serum concentration was determined for a group of coalminers with particularly low levels of lung function, not thought to be explicable in terms of age and dust exposure, and compared with two other groups of coalminers who had average or above average lung function. There was no evidence for an alpha 1 AT deficiency in coalminers with poor lung function. On the contrary, a reactionary increase was evident, even in non-smokers, which may have resulted from the high frequency of chest disease in these men. Within the non-smoking group men with poor lung function had been exposed to higher mean levels of dust, and a greater proportion had early signs of bronchitis. There was no indication that the presence or degree of pneumoconiosis was affecting the results.

Coal Mining↗