PubMed Health⌕ Search

Biomedical subjects

J Grote

Publications and source records attributed to J Grote.

At least 19 recordsLinked to original sources
PubMed2002

Hypoxia influences generation and propagation of electrical activity in embryonic cardiomyocyte clusters.

The influence of tissue hypoxia on the generation and propagation of excitation was studied in spontaneously beating embryonic cardiomyocyte clusters grown in eight 9-12 days old embryoid bodies. Within the embryoid bodies one to three separately active clusters of cardiomyocytes were found, each having its own pacemaker cell. Lowering of tissue PO(2) caused bradycardia as well as arrhythmia in all embryoid bodies investigated. The mean frequency of the extracellularly recorded action potentials decreased under conditions of pronounced hypoxia from a mean of 1.4-1.8 Hz to below 0.8 Hz. In three embryoid bodies hypoxia-sensitive as well as hypoxia-tolerant cardiomyocyte clusters were found. The hypoxia-insensitive cardiomyocytes showed a low frequency of spontaneous activity. In addition to the observed changes in the generation of excitation, tissue hypoxia caused an approximately 60% reduction in the velocity of conduction within the cardiomyocyte clusters. Moreover, in at least one of the eight experiments propagation failure with an incomplete block in spread of excitation was observed. All hypoxia-induced effects on generation and propagation of embryonic cardiomyocyte excitation were completely reversible after reoxygenation.

Animals↗
PubMed2002

Impact of teaching interventions on nurse compliance with hand disinfection.

The impact of teaching interventions and the availability of additional dispensers for alcoholic hand disinfection was measured during three study periods. A nursing care system of relevant nursing interventions was found to be a useful tool for the assessment of compliance with hand hygiene requirements if combined with an analysis of hand disinfectant use. This study shows that compliance with hand disinfection can be improved through targeted teaching and supportive structural improvements, and that this positive impact may persist even after targeted teaching activities have ended.

Guideline Adherence↗
PubMed2000

Efficient synthesis of rhodamine conjugates through the 2'-position.

Reaction of substrates containing primary amines with rhodamine 2'-esters cleanly produces fluorescent rhodamine 2'-amide conjugates at ambient temperature. Only primary amines react with the esters under these conditions. Chemoselectivity can thus be achieved in substrates containing different types of amines.

Amides↗
PubMed2000

Binding interactions of vancomycin tracers with a bacterial cell wall peptidoglycan analogue.

Binding interactions between several vancomycin tracers and (N,N'-diacetyl)KDADA in solution were evaluated in a competition format using a surface plasmon resonance instrument. Tracers derivatized from the carboxy terminus or the N-vancosaminyl sugar moiety of vancomycin bind the peptide with an affinity similar to that of underivatized vancomycin. In contrast, N-methylleucyl derivatized vancomycin tracers bind the peptide with a reduced affinity relative to vancomycin.

Anti-Bacterial Agents↗
PubMed2000

Aprotinin (Trasylol) does not reduce bleeding in primary total hip arthroplasty.

This is a randomized, double-blind, controlled study of the effects of aprotinin (Trasylol) during primary total hip arthroplasty. Sixty patients were randomized to receive either 1.5 x 10(6) KIU of aprotinin or a similar volume of normal saline as a bolus preoperatively. Blood loss was measured from the femoral canal at the time of surgery. An estimate of the total blood loss during the operation was made, and the transfusion requirement was recorded. There was no significant difference between the groups in terms of total blood loss, postoperative hemoglobin, or transfusion requirement. In the group that received aprotinin, there was a trend toward reduced blood loss from the femoral canal, but this was not statistically significant. The results of this study do not support the routine use of aprotinin in primary total hip arthroplasty.

Aged↗
PubMed2000

Does splintage help pain after carpal tunnel release?

A prospective randomized single blind trial was performed of 102 patients undergoing carpal tunnel release. Patients received either a palmar plaster of Paris splint or a bulky wool and crepe bandage postoperatively for the first 48 h, to determine whether the plaster slab reduced postoperative pain. There were no statistically significant differences between the two groups in postoperative pain scores or analgesic use.

Carpal Tunnel Syndrome↗
PubMed1999

Efficient synthesis of 3-aminodigoxigenin and 3-aminodigitoxigenin probes.

Oxidation of digoxigenin and digitoxigenin to the 3-ketones followed by reductive amination produced a mixture of amine epimers. The inability to separate the epimeric mixtures of chemiluminescent digoxigenin probes derived by conjugation to the acridinium label prompted us to develop an HPLC method to separate the amines. Labeling of the pure amines resulted in good yields of the isomerically pure probes.

Cardiotonic Agents↗
PubMed1999

Use of lipase for regioselective one pot amidation and hydrolysis.

A study of the reactivity of esters with oxygenated linkers in lipase catalyzed transformations demonstrates that enhanced reactivity is observed in amidation reactions, but diminished reactivity is observed in hydrolyses using the same lipase. Two regioselective transformations (amidation and hydrolysis) can thus be achieved with diesters in the same pot using a single catalyst, effectively demonstrating lipase's versatility.

Amides↗
PubMed1999

O-(fluoresceinylmethyl)hydroxylamine (OFMHA): a reagent for the preparation of fluorescent O-(fluoresceinylmethyl)oxime (FMO)-steroid conjugates.

The 5 and 6-isomers of O-(fluoresceinylmethyl)hydroxylamine reacted with a representative sample of oxo-steroids (6-oxoestradiol, estrone, norethindrone, cortisol, progesterone, and digitoxin-dialdehyde) to produce O-(fluoresceinylmethyl)oxime conjugates in a single step in 24-84% yield after preparative high performance liquid chromotography.

Chromatography, High Pressure Liquid↗
PubMed1998

Chemo-enzymatic transformations in sensitive systems: lipase mediated hydrolysis of vancomycin esters.

Recently, an interest in the development of new vancomycin derivatives has been demonstrated. Here, the feasibility of using lipases, particularly those from Pseudomonas sp., for the hydrolysis of vancomycin alkyl esters is demonstrated. Benzyl ester derivatives were more easily cleavable than methyl ester derivatives, resulting in good yields of vancomycin acids without degradation.

Anti-Bacterial Agents↗
PubMed1998

Neopterin-induced tumor necrosis factor-alpha synthesis in vascular smooth muscle cells in vitro.

Synthesis and secretion of proinflammatory mediators like tumor necrosis factor-alpha and neopterin are common events in severe systemic inflammatory disorders, e.g. sepsis and septic shock. Recent data suggest that both substances show similarities with respect to their bioactivities. In the present study we investigated the potential interactions of neopterin and tumor necrosis factor-alpha on inducible nitric oxide synthase gene expression and nitric oxide generation in rat vascular smooth muscle cells. In addition, we studied the influence of neopterin on tumor necrosis factor-alpha synthesis in this cell type. Single stimulation of smooth muscle cells with either neopterin or tumor necrosis factor-alpha caused inducible nitric oxide synthase gene expression and nitric oxide production. Coincubation of cells with both compounds resulted in at least additive effects on nitric oxide synthesis. Quantification of tumor necrosis factor-alpha cDNA revealed a dose-dependent effect of neopterin on tumor necrosis factor-alpha gene expression. Similar results were obtained concerning the detection of tumor necrosis factor-alpha protein and the assessment of tumor necrosis factor-alpha bioactivity. These data suggest that neopterin and tumor necrosis factor-alpha are closely associated with regard to synthesis and effects, respectively. The interactions of both inflammatory mediators in vascular smooth muscle cells might contribute to the excessive release of nitric oxide observed during sepsis, thus triggering cellular destruction and multiple organ failure.

Animals↗
PubMed1997

Environmental arsenic exposure of children around a former copper smelter site.

Arsenic residues in the communities surrounding former smelters remain a public health concern, especially for infants and children. To evaluate environmental exposure among these children, a population-based cross-sectional study was conducted in the vicinity of a former copper smelter in Anaconda, Montana. A total of 414 children less than 72 months old were recruited. First morning voided urine samples and environmental samples were collected for arsenic measurements. The geometric mean of speciated urinary arsenic was 8.6 microg/liter (GSD = 1.7, N = 289). Average arsenic levels of different types of soil ranged from 121 to 236 microg/g and were significantly related to proximity and wind direction to the smelter site. The same significant relationship was observed for interior dust arsenic. Speciated urinary arsenic was found to be significantly related to soil arsenic in bare areas in residential yards (P < 0.0005). In general, elevated excretion of arsenic was demonstrable and warranted parents' attention to reduce exposure of their children to environmental arsenic.

Air Pollution, Indoor↗
PubMed1996

Neopterin activates transcription factor nuclear factor-kappa B in vascular smooth muscle cells.

We have previously shown that the pteridine compound neopterin stimulates inducible nitric oxide synthase (iNOS) gene expression in vascular smooth muscle cells in vitro. The mechanisms whereby neopterin exhibits these effects remained unclear. The present study demonstrates that neopterin induces the translocation of the transcription factor nuclear factor-kappa B (NF-kappa B) to the nucleus. Pretreatment of cells with the antioxidant pyrrolidine dithiocarbamate completely suppressed the effects of neopterin on NF-kappa B activation, iNOS gene expression, and nitric oxide release. From these data we conclude that neopterin activates the translocation of NF-kappa B subunits to the nucleus by modulating the intracellular redox state. This is one possible explanation for the impact of neopterin on iNOS gene expression.

Animals↗
PubMed1996

Evaluation of brain tissue O2 supply based on results of PO2 measurements with needle and surface microelectrodes.

Tissue PO2 distribution was measured in rat cerebral cortex during arterial normoxia and arterial hypoxia. The study was designed to examine the relationship between the PO2 histograms determined with surface electrodes in the superficial cortical cells and with needle electrodes in the cortical laminae below. Under normoxic as well as under hypoxic conditions the PO2 distributions of the compared brain regions were in close agreement. The results indicate that PO2 measurements in the brain cortex with surface microelectrodes give a correct view over the tissue oxygenation in cortical regions up to 500 microns below the measuring field.

Animals↗
PubMed1996

A straightforward synthesis of 3 alpha- and 3 beta-aminodigoxigenin.

Pure 3 alpha- and 3 beta-aminodigoxigenin were previously prepared from 12-acetyldigoxigenin by a multistep route involving tosylation, azide inversion, deprotection, and reduction. This paper describes the straightforward synthesis of the pure epimers in a single step via reductive amination of digoxigenone and chromatographic separation without the need for protection and deprotection.

Chromatography↗