Biomedical subjects

K Eckert

Publications and source records attributed to K Eckert.

At least 19 recordsLinked to original sources

PubMed2006

Does using potting mix make you sick? Results from a Legionella longbeachae case-control study in South Australia.

A case-control study was performed in South Australia to determine if L. longbeachae infection was associated with recent handling of commercial potting mix and to examine possible modes of transmission. Twenty-five laboratory-confirmed cases and 75 matched controls were enrolled between April 1997 and March 1999. Information on underlying illness, smoking, gardening exposures and behaviours was obtained by telephone interviews. Recent use of potting mix was associated with illness (OR 4.74, 95% CI 1.65-13.55, P=0.004) in bivariate analysis only. Better predictors of illness in multivariate analysis included poor hand-washing practices after gardening, long-term smoking and being near dripping hanging flower pots. Awareness of a possible health risk with potting mix protected against illness. Results are consistent with inhalation and ingestion as possible modes of transmission. Exposure to aerosolized organisms and poor gardening hygiene may be important predisposing factors to L. longbeachae infection.

Adult↗

PubMed2005

A retrospective study evaluating single-unit red blood cell transfusions in reducing allogeneic blood exposure.

Although guidelines recommend the use of single-unit red blood cell (RBC) transfusions to minimize allogeneic blood exposure, clinical practice remains dominated by two-unit transfusions. This study assesses the potential impact of a single-unit transfusion policy on reducing RBC utilization. We performed a retrospective analysis of adult patients admitted to a tertiary care hospital who received one or two RBC units. In subjects transfused two units, the effect of one unit was estimated by dividing the change in haemoglobin by 2. The proportion of patients reaching a haemoglobin threshold of 70, 75, 80, 85 and 90 g L(-1) with a single RBC unit was estimated. Of 302 included patients, only 65 received a one-unit transfusion. Based on thresholds of > or = 90, > or = 80 and > or = 70 g L(-1), a single-unit transfusion would be sufficient in 42.0% (RRR = 0.54), 79.6% (RRR = 0.23) and 98.0% (RRR = 0.02) of cases, respectively. This corresponds to 0.21, 0.57 and 0.82 mean RBC units saved per patient. In the orthopaedic subpopulation, the mean RBC units saved are 0.53, 0.88 and 1.00 for the same haemoglobin targets. Adopting a policy of transfusing RBC in single-unit aliquots could significantly improve RBC utilization and decrease patient exposure to allogeneic blood.

Erythrocyte Transfusion↗

PubMed2005

Consenting to blood: what do patients remember?

We sought to characterize the consent process for transfusion and determine its impact on patients' knowledge and level of comfort with receiving blood. We identified all adult patients who had received blood transfusion at a tertiary care centre over 3 months. Patients who were discharged each received a survey that assessed their (1) recall of the consent process, (2) recall of information conveyed, (3) assessment of the discussion's understandability and (4) perceived knowledge of as well as comfort level with transfusion as a result of the discussion. Overall, 80% of respondents recalled discussing and signing an informed consent. Information was mostly conveyed by attending physicians (35%) and consent obtained in the patient's hospital room (38%) or the preadmission clinic (19%). Although the majority recalled the consent process, many did not recall the discussion of specific transfusion risks or alternatives to donor blood (88%). Although the majority felt the discussion was at least somewhat understandable (77%), only 35% felt better informed and more comfortable with accepting blood. Despite implementation of written informed consent for transfusion, patients' recollection and understanding of risks and alternatives remain poor. This suggests the need for improving risk communication.

Adolescent↗

PubMed2003

Quantum computing with spatially delocalized qubits.

We analyze the operation of quantum gates for neutral atoms with qubits that are delocalized in space, i.e., the computational basis states are defined by the presence of a neutral atom in the ground state of one out of two trapping potentials. The implementation of single-qubit gates as well as a controlled phase gate between two qubits is discussed and explicit calculations are presented for rubidium atoms in optical microtraps. Furthermore, we show how multiqubit highly entangled states can be created in this scheme.

Journal Article↗

PubMed2002

Gene cloning, sequencing, and characterization of a family 9 endoglucanase (CelA) with an unusual pattern of activity from the thermoacidophile Alicyclobacillus acidocaldarius ATCC27009.

A gene encoding a beta-1,4-glucanase (CelA) belonging to subfamily E1 of family 9 of glycoside hydrolases was cloned and sequenced from the gram-positive thermoacidophile Alicyclobacillus acidocaldarius strain ATCC27009. The translated protein contains an immunoglobulin-like domain but lacks a cellulose-binding domain. The enzyme, when overproduced in Escherichia coli and purified, displayed a temperature optimum of 70 degrees C and a pH optimum of 5.5. CelA contained one zinc and two calcium atoms. Calcium and zinc are likely to be important for temperature stability. The enzyme was most active against substrates containing beta-1,4-linked glucans (lichenan and carboxy methyl cellulose), but also exhibited activity against oat spelt xylan. A striking pattern of hydrolysis on p-nitrophenyl-glycosides was observed, with highest activity on the cellobioside derivative, some on the cellotetraoside derivative, and none on the glucoside and cellotrioside derivatives. Unmodified cellooligosaccharides were also hydrolyzed by CelA. No signal peptide for transport across the cytoplasmic membrane was detected. This, together with the substrate specificity displayed, near neutral pH optimum and irreversible inactivation at low pH, suggests a role for CelA as a cytoplasmic enzyme for the degradation of imported oligosaccharides.

Acids↗

PubMed2001

Substrate specificity and subsite mobility in T. aurantiacus xylanase 10A.

The substrate specificity of Thermoascus aurantiacus xylanase 10A (TAX) has been investigated both biochemically and structurally. High resolution crystallographic analyses at 291 K and 100 K of TAX complexes with xylobiose show that the ligand is in its alpha anomeric conformation and provide a rationale for specificity on p-nitrophenyl glycosides at the -1 and -2 subsites. Trp 275, which is disordered in uncomplexed structures, is stabilised by its interaction with xylobiose. Two structural subsets in family 10 are identified, which differ by the presence or absence of a short helical stretch in the eighth betaalpha-loop of the TIM barrel, the loop bearing Trp 275. This structural difference is discussed in the context of Trp 275 mobility and xylanase function.

Ascomycota↗

PubMed2001

Immersion in water in the first stage of labor: a randomized controlled trial.

BACKGROUND: Current forms of analgesia often have significant side effects for women in labor. Bathing in warm water during labor has been reported to increase a woman's comfort level and cause a reduction in painful contractions. The objective of this trial was to compare immersion in warm water during labor with traditional pain management for a range of clinical and psychological outcomes. METHODS: A prospective randomized controlled trial of 274 pregnant women, who were free from medical and obstetric complications and expecting a singleton pregnancy at term, was conducted at the Women's and Children's Hospital, a maternity tertiary referral center in Adelaide, South Australia. Women in labor were randomized to an experimental group who received immersion in a bath or to a nonbath group who received routine care. Pharmacological pain relief was the primary outcome that was measured, and secondary outcomes included maternal and neonatal clinical outcomes, factors relating to maternal and neonatal infectious morbidity, psychological outcomes, and satisfaction with care. RESULTS: The use of pharmacological analgesia was similar for both the experimental and control groups; 85 and 77 percent, respectively, used major analgesia. No statistical differences were observed in the proportion of women requiring induction and augmentation of labor or in rates of perineal trauma, length of labor, mode of delivery, or frequency of cardiotocographic trace abnormalities. Neonatal outcomes (birthweight, Apgar score, nursery care, meconium-stained liquor, cord pH estimations) revealed no statistically significant differences. Infants of bath group women required significantly more resuscitation than routine group women. Routine group women rated their overall experience of childbirth more positively than bath group women. Psychological outcomes, such as satisfaction with care or postnatal distress, were the same for both groups. CONCLUSION: Bathing in labor confers no clear benefits for the laboring woman but may contribute to adverse effects in the neonate.

Analgesia, Obstetrical↗

PubMed2001

Construction and molecular analysis of gene transfer systems derived from bovine immunodeficiency virus.

Because lentiviruses are able to infect nondividing cells, these viruses might be utilized in gene therapy applications where the target cell does not divide. However, it has been suggested that the introduction of primate lentivirus sequences, particularly those of human immunodeficiency virus, into human cells may pose a health risk for the patient. To avoid this concern, we have constructed gene transfer systems based on a nonprimate lentivirus, bovine immunodeficiency virus. A panel of vectors and packaging constructs was generated and analyzed in a transient expression system for virion production and maturation, vector expression and encapsidation, and envelope protein pseudotyping. Virion preparations were also analyzed for transduction efficiency in a panel of human and nonhuman primary cells and immortalized cell lines. The virion preparations transduced most of the target cell types, with efficiencies up to 90% and with titers of unconcentrated virus up to 5 x 10(5) infectious doses/ml. In addition, infection of nondividing human cells, including unstimulated hematopoietic stem cells and irradiated endothelial cells, was observed.

Adult↗

PubMed2000

Tumor necrosis factor alpha in the pathogenesis of human and murine fulminant hepatic failure.

BACKGROUND & AIMS: The tumor necrosis factor (TNF)-alpha/TNF receptor system is critical for liver development because hepatocytes undergo apoptosis if the antiapoptotic cascades resulting in RelA NF-kappaB activation are not effective. Therefore, we studied the role of TNF-alpha in fulminant hepatic failure (FHF) and developed a new therapeutic strategy. METHODS: Serum levels and hepatic expression of TNF-alpha and both TNF receptors were determined by enzyme-linked immunosorbent assay and immunohistochemistry. Adenoviral vectors were constructed expressing dominant-negative proteins interfering with intracellular TNF-alpha-dependent pathways. The relevance of these constructs was studied in primary mouse hepatocytes and in a murine model of FHF. RESULTS: Serum levels of TNF-alpha and TNF receptors are significantly increased in FHF; this increase correlates with patient prognosis. In livers of patients with FHF, infiltrating mononuclear cells express high amounts of TNF-alpha and hepatocytes overexpress TNF receptor 1 (TNF-R1). Apoptotic hepatocytes are significantly increased in FHF, and there is a strong correlation with TNF-alpha expression, which is even more pronounced in areas of mononuclear infiltrates. In an in vivo FHF model, the Fas-associated death domain (FADD), adenovirus selectively blocked the intracellular pathway, leading to mitochondrial cytochrome c release, caspase-3 activation, and, thus, apoptosis of hepatocytes. CONCLUSIONS: The results show that the TNF-alpha/TNF-R1 system is involved in the pathogenesis of FHF in humans. Studies in this animal model indicate that FADD may serve as a molecular target to prevent liver cell death in vivo.

Adaptor Proteins, Signal Transducing↗

PubMed2000

Convection in two-layer systems with an anomalous thermocapillary effect

Recently, it was found that the anomalous thermocapillary effect (the interfacial tension increases with temperature) is typical for various liquid-liquid systems. We consider the combined action of buoyancy and thermocapillary instability mechanisms in systems with an anomalous thermocapillary effect on the interface. The problem is solved in both linear and nonlinear formulations. A special type of oscillatory instability has been found and investigated.

Journal Article↗

PubMed2000

New Solvatochromic Dyes of the 5-Dimethylamino-5'nitro-2,2'-bithiophene Type.

The first serious competitor to the known solvatochromic pyridiniumphenolate betaines has been uncovered with the 5-dimethylamino-5'-nitro-2,2'-bithiophene 1 a (X=Z=S, Y=CH, R=CH(3)), which has the added benefit of being notably sensitive to solvent in acidic media. By simple heterocyclization further compounds of the general type 1 have been synthesized, and their suitability as solvent indicators was investigated. In this way a new record was set with the selenophene analogue of 1 a.

Journal Article↗

PubMed2000

Environmental enrichment-related injury in a macaque (Macaca fascicularis): intestinal linear foreign body.

A three-year old male cynomolgus macaque (Macaca fascicularis) presented with clinical signs of anorexia and depression that decreased over a 48-hour period. Results of abdominal radiography abdominocentesis, blood biochemical analysis and CBC suggested septic peritonitis. Exploratory laparotomy revealed multiple perforations along the mesenteric border of the small intestine. Necropsy revealed masses of fibrous material in the stomach and cecum. Multiple mucosal ulcerations, as well as linear fibrous material, were found in the small intestine. The ulceration, perforations, and septic peritonitis were attributed to the ingestion of rope that had been attached to the animal's cage as an environmental-enrichment device.

Animals↗

PubMed1999

Nonbound dislocations in hexagonal patterns: pentagon lines in surface-tension-driven Bénard convection.

We report on a novel class of defects in a hexagonal pattern which we call pentalines. They are built up of two nonbound dislocations and are orientated parallel to the roll axis of the mode free of a dislocation. A pentaline has its origin in a transformation of the penta-hepta defect (PHD), taking place at higher supercriticality. The underlying mechanism consists in a combination of glide and climb motion of the original dislocations bound to the PHD. We demonstrate that the pentalines play an important role within the transition from hexagonal towards square convection cells, observed in surface-tension-driven Bénard convection.

Journal Article↗

PubMed1998

Isolation and characterization of two forms of an acidic bromelain stem proteinase.

Two forms of an acidic bromelain proteinase isolated from crude bromelain, an extract from pineapple stem, were found by a two-step FPLC purification procedure. The basic main components were removed by cation exchange chromatography and the breakthrough fraction was further resolved by anion exchange chromatography into 15 protein fractions, only two of which, called SBA/a and SBA/b, were proteolytically active. These components were characterized by electrospray mass spectroscopy (ESMS), isoelectric focusing, N-terminal amino acid sequence analysis, monosaccharide analysis, and enzymatic parameters. The molecular masses of SBA/a and SBA/b were determined by ESMS to be 23,550 and 23,560, respectively. The isoelectric points (pI) of the two bands of SBA/a were 4.8 and 4.9; SBA/b focused as a single band at pI = 4.8. Partial N-terminal amino acid sequences (11 residues) were identical to SBA/a and SBA/b and identical with those of stem bromelain, the basic main proteinase of the pineapple stem, and fruit bromelain, the acidic main proteinase of the pineapple fruit. Both components are highly glycosylated; hydrolysis of SBA/a yielded about twofold more monosaccharide per protein than SBA/b. The comparison of the catalytic properties of SBA/a with those of SBA/b revealed no relevant differences in the hydrolysis of three peptidyl-NH-Mec substrates and in the inhibition profiles using chicken cystatin and E-64, indicating that these components can be considered as two forms of a single enzyme. Both forms are scarcely inhibited by chicken cystatin and slowly inactivated by E-64, hence are nontypical cysteine proteinases of the papain superfamily.

Amino Acid Sequence↗

PubMed1998

Prothymosin alpha1 antagonizes the inhibitory effects of transforming growth factor-beta1 on the adhesion of peripheral blood lymphocytes to human umbilical vein endothelial cells.

We investigated the in vitro effects of both prothymosin alpha1 (Pro alpha1) and transforming growth factor-beta1 (TGF-beta1) on the adhesion of peripheral blood lymphocytes (PBL) and on the expression of the adhesion molecules, endothelial-leukocyte adhesion molecule-1 (ELAM-1), intracellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) on human umbilical vein endothelial cells (HUVECs). TGF-beta1 moderately but significantly decreased PBL-binding to interleukin-1 (IL-1)- stimulated HUVECs. However, Pro alpha1 in combination with TGF-beta1 completely restored the TGF-beta1 mediated effects. Other thymic peptides tested were ineffective. On HUVECs, TGF-beta1 diminished ICAM-1 and VCAM-1 expression, leaving ELAM-1 unchanged. Pro alpha1 in combination with TGF-beta1 showed no significant effects on ELAM-1 expression, but antagonized the TGF-beta1-induced decrease of ICAM-1 and VCAM-1 expression on activated HUVECs.

Cell Adhesion↗

PubMed1998

Docetaxel treatment of HT-29 colon carcinoma cells reinforces the adhesion and immunocytotoxicity of peripheral blood lymphocytes in vitro.

In vitro effects of docetaxel on the human colon carcinoma cell line HT-29 were studied with respect to the expression of different adhesion and surface marker molecules, the adhesion and immunocytotoxicity of peripheral blood lymphocytes and the secretion of IFN-gamma and TNF-alpha. Docetaxel, in a low concentration range (1-3x10-9 M), increased the expression of the adhesion molecules LFA-3, ICAM-1, CD44s, CD44v6, CD15, CD13 and VLA-4/5/6 on the tumor cells. Unstimulated and interleukin-2 (IL-2) activated killer (LAK) cells showed a better adherence to docetaxel treated HT-29 cells than to untreated cells. In neutralization experiments, anti-LFA-3, -CD44v6, -CD15, -VLA -4 and anti-CD13 mAb reduced the lymphocyte adhesion to untreated and docetaxel treated cells at different degrees, while CEA mAb increased the adhesion. Unstimulated and IL-2 activated lymphocytes exhibited significantly higher cytotoxicities against docetaxel treated cells than against untreated HT-29 cells. Unstimulated and IL-2 stimulated lymphocytes secreted more TNF-alpha and IFN-gamma when cocultured with docetaxel treated HT-29 cells than with untreated cells. These results suggest, that the increased lymphocyte mediated cytotoxicity against docetaxel treated HT-29 colon carcinoma cells may reflect an immunological process coupled with induction of differentiation, that may contribute to the clinically known cytostatic effects of the drug.

Antibodies, Monoclonal↗

PubMed1998

Tributyrin induces growth inhibitory and differentiating effects on HT-29 colon cancer cells in vitro.

Tributyrin (TB) is a prodrug of butyrate known to induce tumor cells to differentiate. We examined its effects on cell growth, viability, cellular morphology and differentiation of HT-29 colon cancer cells in vitro, as reflected by the expression of CEA, E-cadherin and the induction of alkaline phosphatase activity. TB, applied in a stable emulsion, inhibited tumor cell proliferation in a reversible and dose-dependent manner (0.5-4 mM) with significant morphological changes. The IC50 value of TB was 1 mM after 6 days. For comparison, sodium butyrate, applied in equimolar concentration, inhibited cell growth with an IC50 value of 2.2 mM. TB treatment at concentrations of 0.5 mM and 2 mM resulted in an increase of the doubling times by 18% and 160%, respectively, without any effects on cell viability. By a colorimetric immunoassay, 1.5 mM TB induced the expression of both CEA and E-cadherin by about 260% and 100%, respectively. Furthermore, the activity of the brush border enzyme alkaline phosphatase was enhanced in a dose-dependent manner, up to 60-fold at the maximum of 2 mM TB. Our results show that TB is more active than butyrate in suppressing cell growth and concomitantly promoting differentiation of HT-29 colon cancer cells. Hence it may be a promising candidate for clinical therapeutic protocols and merits further investigation.

Alkaline Phosphatase↗

PubMed1997

Interleukin-2-activated killer cell activity in colorectal tumor patients: evaluation of in vitro effects by prothymosin alpha1.

The effects of prothymosin alpha1 (Pro alpha1) in combination with interleukin-2 (IL-2) on peripheral blood lymphocytes from 50 colorectal tumor patients at different stages were studied with respect to immunocytotoxicity, adhesion to cultured SW620 colon carcinoma cells, secretion of cytokines and expression of adhesion and surface marker molecules. On average, the patients showed lower natural killer (NK) cell activity than healthy donors, which was associated with a lower adhesion capacity to the tumor target cells. The NK cell activity of the patients was inversely related to the tumor stage. The generation of lymphokine(IL-2)-activated killer (LAK) cell activity was found to be comparable on lymphocytes from healthy individuals and patients and was not correlated to tumor stage. Pro alpha1 stimulated patients' LAK cell activity only, primarily at the early stage (Dukes A/B). The Pro alpha1 effect was associated with an increased adhesion of lymphocytes to tumor target cells and an increased secretion of the deficient IL-2-induced IFN gamma secretion. No significant effects on the low level of TNF alpha secretion was noted. By flow cytometry, Pro alpha1 in combination with IL-2 augmented the expression of the NK cell markers CD56, CD16/56, the subset CD3/16/56 and CD25 on lymphocytes of the patients. In contrast, Pro alpha1 was equally effective by increasing the expression of CD18 and CD11a on lymphocytes from the patients and from normal controls. In conclusion, Pro alpha1, in combination with IL-2, can partially normalize lymphocyte deficiencies of colon cancer patients in vitro. This potential might provide an experimental basis for applying Pro alpha1 or related thymic peptides in selected immunotherapies against colorectal tumors.

Adult↗