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Biomedical subjects

A Brandt

Publications and source records attributed to A Brandt.

At least 73 records · Page 4Linked to original sources
PubMed2001

Ratios of multijet Cross Sections in p p collisions at radical(s) = 1.8 TeV.

We report on a study of the ratio of inclusive three-jet to inclusive two-jet production cross sections as a function of total transverse energy in p&pmacr; collisions at a center-of-mass energy sqrt[s] = 1.8 TeV, using data collected with the D0 detector during the 1992-1993 run of the Fermilab Tevatron Collider. The measurements are used to deduce preferred renormalization scales in perturbative O(alpha(3)(s)) QCD calculations in modeling soft-jet emission.

Journal Article↗
PubMed2001

Inclusive jet production in pp(macro) collisions.

We report a new measurement of the pseudorapidity (eta) and transverse-energy ( E(T)) dependence of the inclusive jet production cross section in pp(macro) collisions at square root of s = 1.8 TeV using 95 pb(-1) of data collected with the D0 detector at the Fermilab Tevatron. The differential cross section d(2)sigma/(dE(T)d eta) is presented up to eta = 3, significantly extending previous measurements. The results are in good overall agreement with next-to-leading order predictions from QCD and indicate a preference for certain parton distribution functions.

Journal Article↗
PubMed2001

Search for large extra dimensions in dielectron and diphoton production.

We report a search for effects of large extra spatial dimensions in pp collisions at a center-of-mass energy of 1.8 TeV with the D0 detector, using events containing a pair of electrons or photons. The data are in good agreement with the expected background and do not exhibit evidence for large extra dimensions. We set the most restrictive lower limits to date, at the 95% C.L. on the effective Planck scale between 1.0 and 1.4 TeV for several formalisms and numbers of extra dimensions.

Journal Article↗
PubMed2001

[Less pain on injection by a new formulation of propofol? A comparison with propofol LCT].

BACKGROUND: Pain on injection is a major disadvantage of propofol, experienced by the vast majority of patients. Since the traditional formulation has almost normal osmolality and pH, it is hypothesised that the concentration of free propofol in the aqueous phase of the emulsion is responsible for the pain and that reducing the amount of free propofol would also reduce the frequency and intensity of pain on injection. This study was designed to investigate whether pain on injection can be reduced in frequency and intensity by a new formulation of propofol. METHODS: We performed a monocentre, controlled, randomised, double-blind study to compare the pain produced by intravenous injection of a new propofol preparation (propofol-MCT/LCT) with standard propofol in patients undergoing elective surgical procedures. A total of 184 non-premedicated patients received either 1% propofol prepared in a mixture of medium and long chain triglycerides (Propofol-MCT/LCT, Propofol- Lipuro, B. Braum Melsungen AG) or standard 1% propofol prepared exclusively in long chain triglycerides (Propofol-LCT; Disoprivan, AstraZeneca) into a vein of the dorsal hand for induction of anaesthesia. Anaesthesia was maintained by TIVA with propofol and remifentanil. Pain on injection was recorded and graded as none, mild, moderate or severe. RESULTS: Patients receiving propofol-MCT/LCT had a significantly lower incidence of pain on injection compared to the standard propofol group (37% vs 64%) with the intensity of pain also being less severe. There were no differences between both groups in propofol dosage for induction (3.2 +/- 0.8 mg/kg vs 3.3 +/- 0.9 mg/kg) and maintenance of anaesthesia (3.4 +/- 0.6 mg/kg/h vs 3.2 +/- 0.5 mg/kg/h), remifentanil dosage (25 +/- 6 micrograms/kg/h vs. 24 +/- 6 micrograms/kg/h), intraoperative hemodynamics, recovery parameters and postoperative patient satisfaction. Postoperative thrombophlebitis at the injection site for propofol was not observed in any of the patients. CONCLUSIONS: Propofol-MCT/LCT produced significantly less pain on injection when compared to standard propofol in ASA I and II patients undergoing elective surgery. Pain was also significantly less severe, with both effects presumably being due to the lower concentration of free propofol in the MCT/LCT-preparation. With regard to injection pain propofol-MCT/LCT offers significant a advantage over standard propofol.

Anesthesia, Intravenous↗
PubMed2001

GLP-1-induced alterations in the glucose-stimulated insulin secretory dose-response curve.

The present study was undertaken to establish in normal volunteers the alterations in beta-cell responsiveness to glucose associated with a constant infusion of glucagon-like peptide-1 (GLP-1) or a pretreatment infusion for 60 min. A high-dose graded glucose infusion protocol was used to explore the dose-response relationship between glucose and insulin secretion. Studies were performed in 10 normal volunteers, and insulin secretion rates (ISR) were calculated by deconvolution of peripheral C-peptide levels by use of a two-compartmental model that utilized mean kinetic parameters. During the saline study, from 5 to 15 mM glucose, the relationship between glucose and ISR was linear. Constant GLP-1 infusion (0.4 pmol x kg(-1) x min(-1)) shifted the dose-response curve to the left, with an increase in the slope of this curve from 5 to 9 mM glucose from 71.0 +/- 12.4 pmol x min(-1) x mM(-1) during the saline study to 241.7 +/- 36.6 pmol x min(-1) x mM(-1) during the constant GLP-1 infusion (P < 0.0001). GLP-1 consistently stimulated a >200% increase in ISR at each 1 mM glucose interval, maintaining plasma glucose at <10 mM (P < 0.0007). Pretreatment with GLP-1 for 60 min resulted in no significant priming of the beta-cell response to glucose (P = 0.2). Insulin clearance rates were similar in all three studies at corresponding insulin levels. These studies demonstrate that physiological levels of GLP-1 stimulate glucose-induced insulin secretion in a linear manner, with a consistent increase in ISR at each 1 mM glucose interval, and that they have no independent effect on insulin clearance and no priming effect on subsequent insulin secretory response to glucose.

Adult↗
PubMed2000

[Increased clinical and economic advantages using PROSIT (proteinuria screening and intervention) in type 2 diabetic patients].

BACKGROUND AND OBJECTIVE: Even though there are simple and cost-effective means for the early diagnosis of diabetic nephropathy, only a small proportion of diabetics in Germany is regularly tests for microalbuminuria. On the basis of evidence-based knowledge and of international guidelines the PROSIT project (proteinuria screening and intervention) aims to make good this deficiency in the German Federal Republic by introducing nephropathy screening and a structured intervention to improve blood sugar and blood pressure regulation, optimizing lipid metabolism and nutritional intake. It was the aim of this study to assess with a computer-aided diabetes model the clinical value and cost-effectiveness of such an intervention. PATIENTS AND METHODS: From data collected for 589 diabetics who participated in the PROSIT project, the short-time effects after one year on HbA1c, systolic blood pressure and lipid levels were obtained and cost-effectiveness compared with that of standard care. Life expectancy, life-time costs to be met by health insurance and event frequency of the diabetic nephropathy stages were calculated with a Markov model for type 2 diabetics. RESULTS: PROSIT improved individual life expectancy by 0.23 years with reduction of life-time costs by DM 9,772 (ca. $4,900). The cumulative incidence of microalbuminuria was lowered by 30.5%, that of terminal renal failure by 55.9%. Even after discounting the results (i.e. the inclusion of time preference for cost and benefit) and stepwise changes of all variables by +/- 10%, PROSIT remained the more cost-effective variant. CONCLUSION: From a health economy viewpoint PROSIT is superior to standard management. Early recognition of albuminuria and the introduction of a multifactorial treatment strategy make it possible to delay progression to terminal renal failure. In addition to its clinical benefits, prevention of dialysis and transplantation would reduce the annual savings of the health care system by several billion DM.

Albuminuria↗
PubMed2000

Measurement of the W-->taunu production cross section in pp collisions at square root s=1.8 TeV.

We report on a measurement of sigma(pp-->W+X)B(W-->taunu) in pp collisions at sqrt[s]=1.8 TeV at the Fermilab Tevatron. The measurement is based on an integrated luminosity (lum) of 18 pb-1 of data collected with the D0 detector during 1994-1995. We find that sigma(pp-->W+X)B(W-->taunu)=2.22+/-0.09 (stat)+/-0. 10 (syst)+/-0.10 (lum) nb. Lepton universality predicts that the ratio of the tau and electron electroweak charged current couplings to the W boson, gWtau/gWe, be unity. We find gWtau/gWe=0.980+/-0.031, in agreement with lepton universality.

Journal Article↗
PubMed2000

Probing Balitsky-Fadin-Kuraev-Lipatov dynamics in the dijet cross section at large rapidity intervals in pp collisions at sqrt[s]=1800 and 630 GeV.

Inclusive dijet production at large pseudorapidity intervals (Deltaeta) between the two jets has been suggested as a regime for observing Balitsky-Fadin-Kuraev-Lipatov (BFKL) dynamics. We have measured the dijet cross section for large Deltaeta in pp collisions at sqrt[s]=1800 and 630 GeV using the D0 detector. The partonic cross section increases strongly with the size of Deltaeta. The observed growth is even stronger than expected on the basis of BFKL resummation in the leading logarithmic approximation. The growth of the partonic cross section can be accommodated with an effective BFKL intercept of alphaBFKL(20 GeV)=1.65+/-0.07.

Journal Article↗
PubMed2000

The cost-effectiveness of different management strategies for type I diabetes: a Swiss perspective.

AIMS/HYPOTHESIS: A computer model was developed to determine the health outcomes and economic consequences of different combinations of diabetes interventions in newly diagnosed patients with Type I (insulin-dependent) diabetes in Switzerland. METHODS: We modelled seven complications of diabetes: hypoglycaemia, ketoacidosis, acute myocardial infarction, stroke, lower extremity amputation, nephropathy, and retinopathy. Transition probabilities and costs were taken from published literature. The Swiss health insurance payer perspective was taken. Various combinations of diabetes management strategies, including intensive or conventional insulin therapy and screening and treatment strategies for renal and eye disease were defined. Life expectancy, cumulative incidences of complications, and mean expected total lifetime costs per patient were calculated under six different management strategies. Incremental cost-effectiveness ratios were calculated in terms of costs per life-year gained compared with conventional insulin therapy alone. RESULTS: The addition of screening for microalbuminuria and retinopathy followed by appropriate treatment, if detected, were cost saving, with reduction in cumulative incidence of end stage renal disease and blindness respectively, and, in the case of microalbulminuria screening and treatment, an improvement in life expectancy. Intensive therapy improved life expectancy but increased total lifetime costs. CONCLUSION/INTERPRETATION: Optimal management of Type I diabetic patients, including secondary and tertiary prevention, leads to reduced complications and improved life expectancy, with the increased costs of prevention offset to varying degrees by cost savings due to complications avoided.

Albuminuria↗
PubMed2000

Outline of a diabetes disease management model: principles and applications.

A complex interactive computer model was developed to determine the health outcomes and economic consequences of different diabetes interventions for user-defined observation periods. The interventions include intensive or conventional insulin therapy, different oral hypoglycaemic medications, different screening and treatment strategies for micro-vascular complications, different treatment strategies for end-stage complications, or multi-factorial interventions. The analyses can be performed on different sub-groups of type 1 and 2 diabetic patients, defined in terms of age, gender, baseline risk factors and pre-existing complications. The model performs real-time simulations. Full on-screen documentation of the model structure, logic, calculations and data sources is available to maximize the model's transparency. Economic and clinical data used in the disease management model are editable by the user, allowing the input of new data as they become available, the creation of country-specific, HMO-specific, or provider-specific versions of the model, and the exploration of new hypotheses ('what-if' analyses). The approach used allows maximum flexibility, adaptability, and transparency within the model structure. For the user-defined patient cohorts and intervention strategies the diabetes disease management model compares life expectancy, expected incidence and prevalence of complications as well as expected life-time (or shorter) treatment cost. Diabetes and complication management strategies can be compared in different patient populations in a variety of realistic clinical settings. The model allows extrapolation of results obtained from relatively short-term clinical trials to longer-term medical outcomes, and from trial populations to real-life populations providing a tangible yardstick to judge the quality of diabetes care. The model was used to evaluate diabetes care options in Germany, France, Switzerland, UK and US.

Computer Simulation↗
PubMed2000

Expression of mammalian RF-amide peptides neuropeptide FF (NPFF), prolactin-releasing peptide (PrRP) and the PrRP receptor in the peripheral tissues of the rat.

The mRNA expression of neuropeptide FF (NPFF), prolactin-releasing peptide (PrRP) and the UHR-1/GPR10 receptor were examined using in situ hybridization in rat peripheral tissues. In the hypophysis, modest expression of PrRP and receptor mRNA were seen in the anterior lobe. The trigeminal ganglion was devoid of expression signals. PrRP and UHR-1/GPR10 receptor mRNA:s were found in the adrenal medulla and PrRP mRNA was found in the pancreas. NPFF mRNA was detected in the spleen. In the testis and epididymis, PrRP and UHR-1/GPR10 receptor mRNA:s were detected. The results suggest a limited expression of mammalian RF-amide peptides in the peripheral organs.

Adrenal Glands↗
PubMed2000

Mutations in ARHGEF6, encoding a guanine nucleotide exchange factor for Rho GTPases, in patients with X-linked mental retardation.

X-linked forms of mental retardation (XLMR) include a variety of different disorders and may account for up to 25% of all inherited cases of mental retardation. So far, seven X-chromosomal genes mutated in nonspecific mental retardation (MRX) have been identified: FMR2, GDI1, RPS6KA3, IL1RAPL, TM4SF2, OPHN1 and PAK3 (refs 2-9). The products of the latter two have been implicated in regulation of neural plasticity by controlling the activity of small GTPases of the Rho family. Here we report the identification of a new MRX gene, ARHGEF6 (also known as alphaPIX or Cool-2), encoding a protein with homology to guanine nucleotide exchange factors for Rho GTPases (Rho GEF). Molecular analysis of a reciprocal X/21 translocation in a male with mental retardation showed that this gene in Xq26 was disrupted by the rearrangement. Mutation screening of 119 patients with nonspecific mental retardation revealed a mutation in the first intron of ARHGEF6 (IVS1-11T-->C) in all affected males in a large Dutch family. The mutation resulted in preferential skipping of exon 2, predicting a protein lacking 28 amino acids. ARHGEF6 is the eighth MRX gene identified so far and the third such gene to encode a protein that interacts with Rho GTPases.

Base Sequence↗
PubMed2000

Lipoxygenases in early Brassica napus germination.

We have identified transcripts of two lipoxygenase (LOXs) from 3-day-germinated etiolated cotyledons. One encodes a soluble and the other encodes a plastid LOX. They are 2520 bp and 2676 bp in size, respectively. Antibodies raised against the C-terminal 500 amino acids of the plastid LOX recognize a 90 kDa LOX in 5-day-old etiolated and green cotyledons. In mature leaves a LOX of 95 kDa is detected. LOX activity and protein was mainly located in the cytosol.

Brassica↗
PubMed2000

Active osmoregulatory ion uptake across the pleopods of the isopod Idotea baltica (Pallas): electrophysiological measurements on isolated split endo- and exopodites mounted in a micro-ussing chamber.

The mechanism of active, osmoregulatory ion uptake was investigated in the pleopods of the marine isopod Idotea baltica (Pallas). Using isolated split half-podites of isopods acclimated to brackish water (20 salinity) mounted in a micro-Ussing chamber and symmetrically superfused with identical haemolymph-like salines, a mean short-circuit current I(sc) of -445 microA cm(-)(2) was measured in endopodites 3-5, corresponding to an inwardly directed transcellular movement of negative charge. Application of ouabain (5 mmol l(-)(1)) to the basolateral superfusate resulted in the almost total abolition of the I(sc) (reduced from -531 to -47 microA cm(-)(2)), suggesting that the Na(+)/K(+)-ATPase is the driving force for active, electrogenic uptake of NaCl. In contrast, mean I(sc) values close to zero were found in preparations of all exopodites and in endopodites 1 and 2. The specific activities of Na(+)/K(+)-ATPase corresponded with these results. Specific activities were highest in posterior endopodites 3-5 and depended on ambient salinity. In all other rami, the activities were much lower and independent of ambient salinity. Activities in posterior endopodites 3-5 were lowest in isopods acclimated to 30 salinity (2-4 micromol P(i )mg(-)(1 )protein h(-)(1)), increased in individuals kept in 20 salinity (8.4 micromol P(i )mg(-)(1 )protein h(-)(1)) and were highest in isopods acclimated to 15 salinity (18.2 micromol P(i )mg(-)(1 )protein h(-)(1)). When specimens were transferred from 30 to 40 salinity, Na(+)/K(+)-ATPase activity increased in the posterior endopodites. The electrophysiological and Na(+)/K(+)-ATPase activity measurements show that active electrogenic ion transport in this species occurs almost exclusively in posterior endopodites 3-5. The endopodite of the fifth pleopod of I. baltica exhibited a microscopic structure remarkably similar to that described for the lamellae of the phyllobranchiae of brachyurans. It is composed of two opposed epithelial monolayers of ionocytes, each covered by cuticle. Bundles of pillar cells are located within the ionocyte layers, which are separated by a fenestrated lamellar septum of connective tissue. The results obtained in this study indicate that endopodites 3-5 play the main role in osmoregulatory ion uptake of the isopod I. baltica. Moreover, the Na(+)/K(+)-ATPase is the only driving force behind active electrogenic ion uptake across the epithelial cells.

Animals↗
PubMed1999

Sequence and analysis of chromosome 4 of the plant Arabidopsis thaliana.

The higher plant Arabidopsis thaliana (Arabidopsis) is an important model for identifying plant genes and determining their function. To assist biological investigations and to define chromosome structure, a coordinated effort to sequence the Arabidopsis genome was initiated in late 1996. Here we report one of the first milestones of this project, the sequence of chromosome 4. Analysis of 17.38 megabases of unique sequence, representing about 17% of the genome, reveals 3,744 protein coding genes, 81 transfer RNAs and numerous repeat elements. Heterochromatic regions surrounding the putative centromere, which has not yet been completely sequenced, are characterized by an increased frequency of a variety of repeats, new repeats, reduced recombination, lowered gene density and lowered gene expression. Roughly 60% of the predicted protein-coding genes have been functionally characterized on the basis of their homology to known genes. Many genes encode predicted proteins that are homologous to human and Caenorhabditis elegans proteins.

Animals↗
PubMed1999

Neuropeptide FF and modulation of pain.

Neuropeptide FF (NPFF) and the related longer peptide neuropeptide AF (NPAF) derive from a single gene in several mammalian species. The gene product is expressed mainly in the CNS, where the posterior pituitary and dorsal spinal cord contain the highest concentrations. Evidence from biochemical and immunohistochemical studies combined with in situ hybridization using NPFF gene-specific probes suggest that all NPFF-like peptides may not derive from the characterized NPFF gene, but that other genes can exist which give rise to related peptides. Intraventricular NPFF exerts antiopioid effects, but intrathecal NPFF potentiates the analgesic effects of morphine. NPFF mRNA expression is upregulated in the dorsal horn of the spinal cord after carrageenan-induced inflammation in the hind paw of the rat, but not in the neuropathic pain model induced by ligation of the spinal roots. NPFF produces a submodality-selective potentiation of the antinociceptive effect induced by brain stem stimulation in the spinal cord during inflammation, and this effect is independent of naloxone-sensitive opioid receptors. In neuropathic animals, NPFF injected into the periaqueductal grey produces a significant attenuation of tactile allodynia, which is not modulated by naloxone. NPFF thus modulates pain sensation and morphine analgesia under normal and pathological conditions through both spinal and brain mechanisms.

Animals↗
PubMed1999

Determination of silymarine in the extract from the dried silybum marianum fruits by high performance liquid chromatography and capillary electrophoresis.

Silybine (SBN), isosilybine (ISBN), silycristine (SCN), silydianine (SDN), and taxifoline (TXF) are the main active flavanoids, generally found in the dried fruits of silybum marianum. The concentrations of these compounds, excepted TXF, are all together usually expressed as silymarine content. In this paper the determination of the silymarine titre was made by high performance liquid chromatography (HPLC), and high performance capillary electrophoresis (HPCE). Two reversed stationary phases, RP-18 and RP-8, were observed comparing the resolutions of all considered flavanoids with each stationary phases. The HPCE was carried out considering the possible improvement in the resolution of SBN, CN, SDN and TXF using, 8-cyclodextrines or organic modifier. The qualitative and quantitative data obtained by HPLC and HPCE were compared.

Chromatography, High Pressure Liquid↗