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Biomedical subjects

A Brock

Publications and source records attributed to A Brock.

At least 19 recordsLinked to original sources
PubMed2006

Mortality from all cancers and lung, colorectal, breast and prostate cancer by country of birth in England and Wales, 2001-2003.

Mortality from all cancers combined and major cancers among men and women aged 20 years and over was compared by country of birth with that of the whole of England and Wales as the reference group. Population data from the 2001 Census and mortality data for 2001-2003 were used to estimate standardised mortality ratios. Data on approximately 399 000 cancer deaths were available, with at least 400 cancer deaths in each of the smaller populations. Statistically significant differences from the reference group included: higher mortality from all cancers combined, lung and colorectal cancer among people born in Scotland and Ireland, lower mortality for all cancers combined, lung, breast and prostate cancer among people born in Bangladesh (except for lung cancer in men), India, Pakistan or China/Hong Kong, lower lung cancer mortality among people born in West Africa or the West Indies, higher breast cancer mortality among women born in West Africa and higher prostate cancer mortality among men born in West Africa or the West Indies. These data may be relevant to causal hypotheses and in relation to health care and cancer prevention.

Adult↗
PubMed2005

Expression and characterization of six clinically relevant uroporphyrinogen decarboxylase gene mutations.

The functional consequence of six uroporphyrinogen decarboxylase (UROD) gene mutations found in Danish patients with familial porphyria cutanea tarda was investigated. Wild-type UROD and the 6 mutants (3 missense, 1 nonsense and 2 frameshift mutants) were cloned and expressed using the prokaryotic gGEX-6P system, in which the protein is produced in fusion with glutathione S-transferase (GST). Enzymatic activity of the purified recombinant mutant fusion proteins ranged from undetectable to less than 12% of the recombinant wild-type protein. Mutant proteins cleaved from the GST part did not retain any catalytic activity. These observations can be ascribed to the structure/function relationships of the enzyme, and the fact that the enzyme is a dimer in its active form. Although the clinical manifestation of familial porphyria cutanea tarda is complex, the findings support the notion that different mutations may affect individuals differently.

Gene Expression↗
PubMed2001

Expanding the genetic code of Escherichia coli.

A unique transfer RNA (tRNA)/aminoacyl-tRNA synthetase pair has been generated that expands the number of genetically encoded amino acids in Escherichia coli. When introduced into E. coli, this pair leads to the in vivo incorporation of the synthetic amino acid O-methyl-l-tyrosine into protein in response to an amber nonsense codon. The fidelity of translation is greater than 99%, as determined by analysis of dihydrofolate reductase containing the unnatural amino acid. This approach should provide a general method for increasing the genetic repertoire of living cells to include a variety of amino acids with novel structural, chemical, and physical properties not found in the common 20 amino acids.

Anticodon↗
PubMed2001

A novel multifunctional labeling reagent for enhanced protein characterization with mass spectrometry.

Individual peptides with lysine at the C-terminus as well as protein tryptic digests were reacted with 2-methoxy-4,5-dihydro-1H-imidazole, converting lysine residues to their 4,5-dihydro-1H-imidazol-2-yl derivatives. The mass spectra of derivatized digests exhibit a greater number of more intense features than their underivatized counterparts, thus increasing the information obtained in peptide mapping experiments. Additionally, MS/MS spectra of the derivatized peptides are greatly simplified in comparison to their native species, yielding primarily an easily interpretable series of y-ions. Finally, this novel label also enables differential quantitation studies, as a stable isotopic form containing four deuterium atoms can readily be produced.

Amino Acid Sequence↗
PubMed2000

[Acute porphyria].

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Acute Disease↗
PubMed2000

[Acute porphyria].

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Acute Disease↗
PubMed2000

DGGE analysis of the coproporphyrinogen oxidase gene: two new mutations in DNA from Danish patients with hereditary coproporphyria.

The knowledge of at least 21 different mutations and several polymorphisms in the coproporphyrinogen oxidase (CPO) gene demonstrates that the molecular basis of hereditary coproporphyria is heterogeneous. We developed a DGGE-based assay for the analysis of exons 2 to 7, including 14-96 nucleotides of the flanking intronic sequences of the CPO gene. To render it suitable for the clinical diagnostic laboratory, we designed the assay to allow use of identical PCR conditions and the same DGGE gel for analyses of all the regions. Using this assay, and subsequent sequencing of gene regions containing interallelic variations, two novel mutations in the CPO gene were identified: a missense mutation (607G-->A), leading to the substitution of an alanine with a threonine, and a nonsense mutation (1281G-->A), giving rise to a stop codon 28 codons upstream to the wild-type stop codon.

Amino Acid Sequence↗
PubMed2000

Determination of porphobilinogen deaminase activity in human erythrocytes: pertinent factors in obtaining optimal conditions for measurements.

Determination of porphobilinogen deaminase (PBGD; EC 4.3.1.8) activity in erythrocytes can contribute to the identification of patients suspected of acute intermittent porphyria. PBGD catalyses the polymerization of four molecules of porphobilinogen (PBG) to the highly unstable 1-hydroxymethylbilane. The 1-hydroxymethylbilane is transformed into uroporphyrinogen III by uroporphyrinogen III synthase. When this enzyme is inactivated, 1-hydroxymethylbilane cyclizes non-enzymatically to uroporphyrinogen I, which can be oxidized to uroporphyrin I. PBGD activity can be measured by quantitation of uroporphyrin I formed from PBG under conditions where this is the only end product. The purpose of the present study was to define the optimal conditions for quantitating PBGD activity in human erythrocytes. The preanalytical factors examined were: anticoagulants and methods for disruption of the erythrocytes. The analytical factors examined were: duration of preincubation, reaction time, reaction temperature, pH, ionic strength and conditions for the oxidation of uroporphyrinogen I to uroporphyrin I. Based on the results, we propose an optimized method for determination of PBGD activity in erythrocytes.

Adult↗
PubMed2000

Activity and immunohistochemical localization of porphobilinogen deaminase in rat tissues.

Porphobilinogen deaminase (PBGD) is an enzyme involved in the synthesis of heme. Acute intermittent porphyria (AIP) is an inherited disease resulting from a reduced activity of PBGD. The symptoms seem to be due to a neurological dysfunction. Attacks of AIP are often provoked by conditions where the PBGD activity becomes insufficient as a result of an increased synthesis of heme in the liver. How this affects the nervous tissue is still unknown. It may well be that a reduced activity of PBGD in other tissues than the liver is of importance too. The aim of the present study was to examine the activity and the immunohistochemical localization of PBGD in the following tissues of wistar female rats: brain, heart, submandibular gland, liver, kidney, pancreas, ovary, stomach, duodenum, jejunum, ileum, colon and musculature. The PBGD activity varied considerably among the tissues. It was highest in the liver, 14 pkat/g, and lowest in the jejunum, 0.7 pkat/g. The immunohistochemical localization of PBGD was studied by antibodies raised against a 40 amino acid synthetic peptide that corresponds to a segment in the C-terminal part of PBGD. The study demonstrated that the PBGD immunoreactivity was not evenly distributed among the various cell types in a given tissue. Immunohistochemical reactions were pronounced in Kupffer cells in the liver, in smooth muscle cells of arteries and arterioles, in distal and collecting tubules in the kidney, in nerve axons in the brain and in ganglionic cells in the intestine. Especially, the immunohistochemical reaction in nerve cells is notable considering the nervous dysfunction in AIP.

Amino Acid Sequence↗
PubMed2000

Porphyrins, porphyrin metabolism and porphyrias. II. Diagnosis and monitoring in the acute porphyrias.

The acute porphyrias constitute a group of metabolic disorders engaging enzymes in the haem synthetic chain and generally following dominant inheritance patterns. Some gene carriers are vulnerable to a range of exogenous and endogenous factors, which may trigger neuropsychiatric symptoms. Early diagnosis is of prime importance since it makes way for counselling with the aim to block the development of acute, as well as late, disease. The medical and psycho-social consequences of a porphyria diagnosis are considerable and the freedom for maldiagnosis correspondingly small. The strain imposed upon the diagnostic process makes management in specialized laboratories necessary. Inadvertent handling of the diagnostic procedures in laboratories lacking in knowledge, experience and technical competence is repeatedly the reason for harmful underdiagnosis and overdiagnosis. Gene diagnosis of the carrier condition, principally within reach in all types of acute porphyria, is of incomparable versatility and accuracy. However, despite recent great achievements in the molecular biology of porphyric disease, genomic procedures cannot replace biochemical methods in monitoring the activity and progress of the disease, or the effects of therapy. The classical methods are also useful when it comes to screening for the associated disease states. In these tasks, professional handling of the methods and skillful interpretation of the results are of paramount importance. Knowledge of the limitations and pitfalls of the procedures is a guard against maldiagnosis, which may be fatal. In the article the main diagnostic challenges are discussed; the strategy for early detection of the gene carrier state, the recognition and surveillance of the acute porphyric crisis, the evaluation of subacute/subchronic symptoms, the differential diagnoses of the cutaneous porphyrias and the monitoring of late complications.

Acute Disease↗
PubMed1997

[Alcohol consumption and liver enzymes in persons 30-50 years of age. Cross-sectional study from Ebeltoft].

In a representative population sample of 905 persons we examined the prevalence of raised levels of liver-derived enzymes and its possible association with self-reported alcohol consumption adjusted for smoking and BMI applying logistic regression analyses. A large proportion of 12% (women 8%; men 16%) presented raised liver-derived enzymes. Below 21 units per week (one unit equals 12 grams of alcohol) there was no association with self-reported alcohol consumption. However, the risk of abnormal liver enzymes increased with higher consumption for both sexes; if the intake was above 28 units per week, the odds ratio for raised liver enzymes increased dramatically. Whether this subclinical biochemical liver condition is an early marker of alcohol-related liver damage remains to be seen, but the long-term consequences of the reported alcohol consumption and the frequency of raised liver enzymes require follow-up.

Adult↗
PubMed1997

Iopentol (Imagopaque 250) compared with diatrizoate (Urografin 219) in endoscopic retrograde cholangio-pancreatography (ERCP). A clinical trial assessing safety (adverse events and S-pancreatic iso-amylase) and diagnostic information (VAS).

The efficacy and safety of the non-ionic contrast medium iopentol, 250 mg I/ml (Imagopaque, Nycomed Imaging AS, Oslo, Norway) were evaluated and compared to those of the ionic contrast medium diatrizoate 219 mg I/ml (Urografin, Schering AG, Berlin, Germany). The trial was carried out as a randomized, double-blind comparative two-group study. One hundred and sixteen patients completed the study: 59 received iopentol and 57 received diatrizoate, the contrast medium used according to routine hospital procedure for ERCP. Demographic data and details of the ERCP procedure were comparable for the two contrast medium groups. Safety was assessed by monitoring serum pancreatic iso-amylase and by recording adverse events. Efficacy was evaluated through assessment of the diagnostic information and the quality of radiographs. Twenty-one of the patients receiving iopentol and 27 of the patients receiving diatrizoate reported adverse events during the ERCP procedure. Pain was the kind of procedure-related event most frequently reported. Three patients experienced serious adverse events with a fatal outcome 2, 10 and 12 days after the ERCP procedure, respectively. The principal investigator concluded for all three serious adverse events that any causal relationship with the contrast medium injected was unlikely. A mean change in serum pancreatic iso-amylase after contrast medium injection was noted in both contrast medium groups. However, statistical analysis did not show any significant difference between mean changes for the two groups. The efficacy results, both in terms of diagnostic information and quality of radiographic visualisation, were comparable for the two contrast media. In conclusion, the study did not show any statistically significant differences between the two contrast media as regards safety or efficacy in ERCP.

Amylases↗
PubMed1997

Alcohol consumption and serum liver-derived enzymes in a Danish population aged 30-50 years.

BACKGROUND: Based on the increased consumption of alcohol in Denmark the aim of this study was to measure prevalence of abnormal liver-derived enzymes in a homogeneous Danish population and possible associations with alcohol consumption, smoking and body mass index (BMI). METHOD: In a representative population sample of 905 people (aged 30-50) from the baseline survey of the Ebeltoft Health Promotion Project in Denmark, we examined prevalence of abnormal liver-derived enzymes and its possible association with self-reported alcohol consumption, smoking and BMI, applying logistic regression analyses. RESULTS: In a significant proportion, 12% (women 8%; men 16%) of the cohort we found raised levels of liver-derived enzymes associated with moderate self-reported alcohol intake adjusted for BMI and smoking. If the intake was higher than moderate, i.e. > 28 units per week (one unit equals 12 g of alcohol), the odds ratio (OR) for raised liver enzymes increased further; S-gamma-glutamyltransferase (GGT) (OR: for women 24.4; men 18.4). S-aspartate-aminotransferase (ASAT) (24.2; 5.8) and S-alanine-aminotransferase (ALAT) (27.2; 3.0). Furthermore, daily smoking increased the risk of raised liver enzymes in women (OR: 3.4-4.2), and obesity (BMI > or = 30 kg/m2) in men showed a positive association with all three enzymes (OR: 3.0-9.0). CONCLUSIONS: The occurrence of raised liver-derived enzymes was frequent in the Danish population sample and associated with moderate self-reported alcohol consumption adjusted for BMI and smoking.

Adult↗
PubMed1996

Optimizing nursing through reorganization: mandates for the new millennium.

The issues surrounding health care reform are mandating change for every health care profession. Nursing as it has been configured over the last several decades will not work for the millennium. This article discusses the recommendations specific to nursing for accommodating the health care needs of the American people reported by the most recent study of the Pew Health Care Commission. The authors present a three-level nursing care delivery model based on educational preparation.

Education, Nursing↗
PubMed1995

[The initial results on the radiobiological comparability of continuous LDR irradiation and PDR irradiation using a guinea pig skin animal model].

AIMS: The classic continuous low dose rate (LDR) brachytherapy was very important in such cases with a higher risk of severe especially late radiation reactions. From clinical experiences and radiobiological considerations it is known, that the therapeutic ratio of LDR is higher than HDR. Another way to combine the therapeutic ratio of LDR and the possibility of optimisation is the use of pulse dose rate (PDR) technique. The PDR-technique is a method, which can be compared with continuous LDR-therapy. PDR should have biological effects equivalent to conventional LDR. MATERIAL AND METHODS: We have tried to compare the classic continuous LDR-technique with 2 PDR-regimes by means of the guinea pig skin model. In this test series we involved 20 female animals with an initial weight of 400 to 500 g. We compared radiation reactions of following regimes: 1. Continuous LDR regimen with a cobalt-60 source with an activity of 5.5 mCi 30 Gy in 60 hours. 2. PDR regimen 0.5 Gy hourly, pulse length minimal 10 minutes, 30 Gy in 60 hours with an Ir-192 source with an activity of nearly 40 mCi. 3. PDR-regimen 0.8 Gy hourly with 9 hours night break (10.00 p. m. to 7.00 a. m.). The radiation reaction was controlled by the help of an evaluation table in which the criteria of radiation reaction were classified according to the degree of seriousness. The observation time is now minimal 14 and maximal 24 months. RESULTS: The findings shows a significant coincidence of early and late radiation reactions of the skin fields irradiated with the continuous LDR-technique and fields irradiated with the PDR-technique. There was not a difference of the radiation reactions between PDR-irradiation with and without night break. CONCLUSIONS: Generally it is possible to compare the radiation reactions of PDR-irradiation and the classic continuous LDR-brachytherapy. It is also possible to use a PDR-regimen with a night break of 9 hours. But results must be calculated for each tissue of interest, in our test consequently for guinea pig skin.

Animals↗
PubMed1994

Parathyroid hormone in blood pressure and volume homeostasis in healthy subjects, hyperparathyroidism, liver cirrhosis and glomerulonephritis. A possible interaction with angiotensin II and atrial natriuretic peptide.

In order to elucidate a participation of intact parathyroid hormone (PTH(1-84)) in blood pressure (BP) and body fluid homeostasis, we studied fluctuations of PTH(1-84) during manipulations of BP in hyperparathyroid and healthy subjects, and during manipulations of blood volume in patients with glomerulonephritis or liver cirrhosis and in controls. Angiotensin II induced BP elevation was associated with increased values of PTH(1-84) both in healthy subjects (12-25 ng l-1, medians, p < 0.01), in patients with primary hyperparathyroidism (94-125 ng l-1, p < 0.01), in patients with low calcium due to end stage renal disease before requirement of dialysis (95-151 ng l-1, p < 0.02), and in patients with tertiary hyperparathyroidism (221-264 ng l-1, p < 0.05), but not in dialysis patients without hypercalcaemia (126-174 ng l-1, NS). The changes could not be attributed to reduction of serum calcium, but probably to the increase of plasma angiotensin II, which was positively correlated to the increase of serum PTH(1-84) in the healthy subjects (p = 0.619, n = 15, p < 0.05) and in the patients with primary hyperparathyroidism (p = 0.549, n = 18, p < 0.05). Noradrenaline induced BP elevation did not have a similar effect on PTH(1-84), and changes of PTH(1-84) were not related to changes of BP. Volume depletion after furosemide injection, also accompanied by increased levels of angiotensin II, resulted in elevation of PTH(1-84) in controls, cirrhotics, patients with glomerulonephritis without the nephrotic syndrome, but not in nephrotic patients. Volume depletion induced by bolus injection of atrial natriuretic peptide (ANP) was associated with decreased PTH(1-84) in healthy subjects (20-18 ng l-1, p < 0.02), but not in patients with nephrotic syndrome and liver cirrhosis. Volume expansion induced by albumin infusion caused increased plasma levels of ANP, but PTH(1-84) was unaltered. Thus, angiotensin II may be able to stimulate, and ANP to inhibit release of PTH(1-84), and PTH(1-84) may be involved in the regulation of BP and body fluid homeostasis. BP changes or changes in blood volume per se do not seem to influence PTH(1-84) levels.

Adolescent↗