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Biomedical subjects

K C Thompson

Publications and source records attributed to K C Thompson.

At least 19 recordsLinked to original sources
PubMed2003

A comparison of desiccant materials used for monitoring atmospheric tritium concentrations in a semi-arid climate.

Atmospheric tritium monitoring involves the collection of tritiated water vapor by collecting atmospheric moisture from air that is drawn through a bed of desiccant material. This study is a comparison between molecular sieve and silica gel adsorbent media used for atmospheric moisture sampling conducted in the semi-arid climate of the Idaho National Engineering and Environmental Laboratory. Water vapor was collected simultaneously using two columns containing different desiccant materials (one column containing molecular sieve and the other containing silica gel). Data collected during air sampling periods were compared with meteorological data collected, and atmospheric moisture collection efficiencies were determined. Breakthrough of atmospheric moisture past the desiccant material was suspected with both media at elevated temperatures indicating that smaller sample volumes, lower volumetric flow rates, or longer adsorbent columns should be used during summer when ambient temperatures are elevated.

Air Pollutants, Radioactive↗
PubMed2003

A field test of electret ion chambers for environmental remediation verification.

In 1999, the State of Idaho INEEL Oversight Program performed a field test to determine if electret ion chambers could be used as a replacement to soil sampling in field survey releases at a remediated radioactively contaminated site. This study compared exposure rates measured using electret ion chambers with gamma spectroscopic analysis results of soil samples collected at the remediated site. Exposure rate measurements were made in 1999 using electret ion chambers at the same locations that INEEL Oversight Program sampled soil in 1998 following MARSSIM protocol. The waste site was divided into nine survey units based upon site history including previous site surveys and physical boundaries. Exposure rate measurements at the remediation site compared well with exposure rate measurements made at reference background locations used for routine environmental monitoring by the State of Idaho indicating that the remedial action met cleanup criteria. A poor correlation between exposure rate measurements and 137Cs concentrations and other discrepancies were observed during this study with respect to measurements made during the 1998 final site survey.

Biodegradation, Environmental↗
PubMed2001

Diclazuril preventive therapy of gamma interferon knockout mice fed Sarcocystis neurona sporocysts.

Gamma interferon knockout (KO) mice (n=74) were fed a lethal dose of approximately 1000 sporocysts of the SN15-OP isolate of Sarcocystis neurona. Groups of mice were given pelleted rodent feed containing 50ppm of diclazuril at different times before and after feeding sporocysts. All mice were examined at necropsy and their tissues were examined immunohistochemically for S. neurona infection. Twenty mice were fed sporocysts and given diclazuril starting 5 days before feeding sporocysts and continuing 30-39 days post-infection (p.i.). One mouse died of causes unrelated to S. neurona with no demonstrable parasites; the remaining 19 mice remained clinically normal and S. neurona organisms were not found in their tissues. Sarcocystis neurona organisms were not demonstrable by bioassay of the brains of these 19 mice in uninfected KO mice. Sarcocystis neurona organisms were not found in tissues of five mice treated with diclazuril, starting 7 days after feeding sporocysts and continuing up to 39 days p.i. Therapy was less efficient when diclazuril was given 10 days p.i. Sarcocystis neurona organisms were found in two of 19 mice treated with diclazuril starting 10 days after feeding sporocysts, in two of five mice starting therapy 12 days p.i., and in 10 of 10 mice when treatment was delayed until 15 days p.i. All 15 mice fed S. neurona, but not given diclazuril, developed neural sarcocystosis and were euthanized 22-30 days after feeding sporocysts. Six mice not fed S. neurona, but given diclazuril for 44 days, remained clinically normal. Results indicate that diclazuril can kill the early stages of S. neurona.

Animals↗
PubMed2000

On-line separation and determination of bromate in drinking waters using flow injection ICP mass spectrometry.

A flow injection (FI) system with a microcolumn of anion exchanger has been used to effect rapid on-line separation of bromate and bromide prior to quantitation by ICP mass spectrometry. Basic performance studies are described including the effect of key FI parameters, i.e., sample injection volume, carrier stream flow rate, and eluent concentration on system response. The new approach permitted ultratrace determinations of bromate in drinking waters, the main benefits being low limit of detection (0.13 microg/L based on a 500-microL sample injection), rapid analysis time (10 min/sample), and good precision (2.8% at the 5 microg/L level). Accuracy was checked via an EC-sponsored interlaboratory trial.

Journal Article↗
PubMed2000

Interlaboratory trial to determine the analytical state-of-the-art of bromate determination in drinking water.

The new European Directive for water intended for human consumption has established a regulatory level for bromate at 10 microg L(-1). This Maximum Admissible Concentration requires analytical methods with detection limits of a least 2.5 microg L(-1). A project funded by the Standards, Measurements and Testing Programme of the European Commission has enabled the improvement and/or development of methods for the determination of bromate at such concentration levels. This collaborative work was concluded by the organisation of an interlaboratory trial involving 26 European laboratories, which enabled the testing of both a draft ISO Standard method and alternative methods. This paper presents the results of this interlaboratory trial, along with results of a bromate stability study. The progress made with respect to the analytical state-of-the-art for bromate will greatly benefit the quality of measurements carried out in water quality monitoring.

Bromates↗
PubMed2000

Effect of eltenac in horses with induced endotoxaemia.

Ten horses were used in a crossover study to evaluate the effectiveness of eltenac against endotoxaemia. Eltenac (0.5 mg/kg bwt) or saline control was given i.v. then 15 min later, intravenous infusion of endotoxin was begun and continued for 120 min (total dose 100 ng/kg bwt). Horses were monitored for heart and respiratory rates, pulmonary and carotid arterial pressure and core body temperature. Blood was sampled at intervals for measurement of haematological variables and plasma concentrations of lactate, prostanoid metabolites, tumour necrosis factor (TNF) and stress hormones. In comparison with saline-treatment, use of eltenac significantly protected against endotoxin-induced changes in respiratory rate, core temperature, systemic arterial blood pressure (SAP), pulmonary arterial pressure, PCV, and plasma protein, 6-keto prostaglandin F1 alpha, thromboxane B2, epinephrine, and cortisol concentrations. Despite statistical effect of eltenac on SAP, values in both treatment groups remained well above baseline throughout the evaluation period. Significant protective effect of eltenac was not found for heart rate, white blood cell count, plasma lactate concentration or TNF activity. On the basis of these results, it is expected that use of eltenac will provide clinical benefit in horses with naturally occurring endotoxaemia.

Aniline Compounds↗
PubMed1999

Investigation of the polymorphism of the angiotensin II antagonist agent MK-996.

The polymorphism of the angiotensin II antagonist agent MK-996 was studied, with particular emphasis on crystal form stability, solubility, and reproducible crystallization of the drug. X-ray powder diffraction patterns indicated differences in the crystal forms of early research and development lots. Solubility data for the different crystal forms in water at 25 degrees C are in agreement with the solution calorimetry data and indicated that crystalline form I is the thermodynamically stable polymorph of MK-996 under ambient conditions. In contrast to the other polymorphs, form I is reproducibly prepared on both the laboratory and production scale. This study examines methodology to determine the most suitable polymorph for development.

Angiotensin Receptor Antagonists↗
PubMed1999

A qualitative examination of borderline personality disordered (BPD) patients: interpersonal dynamics and underlying paradoxes.

Theoretical conceptualizations of symptomatology in patients with borderline personality disorder (BPD) have noted an inability to integrate contradictory perceptions (splitting, or dichotomous thinking) as a hallmark of the disorder. This study investigated contradictions manifest in the thinking and behavior of BPD patients, using the concept of paradox. A paradox occurs when an apparent contradiction contains an underlying logic which makes the contradiction comprehensible. Using qualitative methods of analysis, this study explored paradoxes evident in 10 BPD patient narratives about relationship events. Specific paradoxes relating to interpersonal conflicts and self-destructiveness are presented, along with the underlying logic of each paradox as described by patients. Implications for treatment are discussed.

Borderline Personality Disorder↗
PubMed1998

Primary rat and mouse hepatic stellate cells express the macrophage inhibitor cytokine interleukin-10 during the course of activation In vitro.

Activation of local tissue macrophages (Kupffer cells) and of quiescent hepatic stellate cells (HSCs) to a myofibroblast phenotype are two key events in liver inflammation and fibrosis. It is known that products of activated macrophages may activate stellate cells. We have hypothesized that the products of activated HSCs may also modulate the activity of Kupffer cells. The cytokine interleukin-10 (IL-10), produced by lymphocytes and macrophages, has profound inhibitory actions on macrophages. Normal rat and mouse HSCs that differentiate in vivo and in vitro to activated myofibroblasts were isolated by enzyme perfusion and density centrifugation with or without centrifugal elutriation, confirmed by vitamin A autofluorescence and positive immunostaining for the myofibroblast markers desmin and smooth muscle actin (SMA). Conditioned media and lysates from these cells were found to down-regulate lipopolysaccharide (LPS)-induced tumor necrosis factor- (TNF-) secretion by the mouse macrophage line RAW 267.4. In highly purified preparations of rat HSCs, messenger RNA (mRNA) for IL-10 was detected by reverse-transcription polymerase chain reaction (RT-PCR), from the time of isolation to up to 120 days of culture on plastic. Long-term cultures of unstimulated mouse HSCs secreted IL-10 protein as detected by immunoblotting and specific enzyme-linked immunosorbent assay (ELISA). IL-10 protein was undetectable by immunohistochemistry in mouse HSCs for the first 3 days in culture. After this, the percentage of IL-10-positive cells increased to 45% at day 7 and 100% by day 14, and expression of IL-10 continued in long-term cultures of up to 120 days. The expression of IL-10 by the stromal cells that govern the fibrotic process in the liver may have important implications for the regulation of inflammation and fibrosis in the liver.

Animals↗
PubMed1998

Benign superior vena cava syndrome due to suppurative mediastinal lymphadenitis: anterior mediastinoscopic management.

The benign superior vena cava syndrome is an uncommon medical emergency. We describe a case of the superior vena cava syndrome caused by suppurative mediastinal lymphadenitis. The organisms isolated from various cultures were group C beta-hemolytic Streptococcus, Fusobacterium species, Corynebacterium species, Eikenella corrodens, and Streptococcus milleri. These anaerobic bacteria are part of the normal flora of the upper respiratory tract and the oral cavity. Anterior mediastinoscopy through the right parasternal approach was used to drain the anterior mediastinal abscess and to establish the etiologic factor.

Adult↗
PubMed1997

Determination of an effective dose of eltenac and its comparison with that of flunixin meglumine in horses after experimentally induced carpitis.

OBJECTIVES: To titrate a clinically effective eltenac dosage (0.1, 0.5, and 1.0 mg/kg of body weight), compared with vehicle only, and to compare efficacy of the most effective eltenac dosage with that of 1.1 mg of flunixin meglumine/kg. ANIMALS: 40 healthy horses, ranked after model induction on the basis of lameness severity, were randomly assigned to 5 treatment groups, with 4 replicates of 10 horses each. PROCEDURE: On day -5, after surgical preparation of the left carpal region, 0.7 ml of Freund's complete adjuvant was injected into the intercarpal space. Horses were observed daily, from the day of carpitis induction to day 0, when stride length was used as the method of ranking horses for randomization to treatment assignment. Treatments were administered i.v. once daily for 3 consecutive days, starting on day 0. Prior to carpitis induction on day -5, and at time 0 (pretreatment), 2, 4, 12, 24, 36, 48, 60, 72, and 96 hours after treatment initiation, resting respiratory rate and pulse, rectal temperature, carpal circumference, carpal flexion angle, stride length, carpal hyperthermia, and signs of carpal pain were recorded. RESULTS: Compared with the vehicle and 0.1 mg of eltenac/kg, 0.5 and 1.0 mg/kg caused statistically significant improvements (ie, reduction of carpal circumference, increase in carpal flexion angle, and increase in stride length of the affected limb), but values did not differ significantly between the 2 dosages. Thus, a dose-response plateau for eltenac was reached at 0.5 mg/kg. Comparison with flunixin meglumine at a dosage of 1.1 mg/kg did not indicate significant differences between the 2 treatment groups at the pivotal time of 96 hours for carpal circumference, carpal flexion angle, stride length, carpal hyperthermia, and signs of carpal pain. Adverse reactions were not observed. CLINICAL RELEVANCE: Under conditions of this study, a dosage plateau for eltenac was determined (0.5 mg/kg) that was statistically equivalent to eltenac (1.0 mg/kg) and flunixin meglumine (1.1 mg/kg) in a 3-day i.v. dosing regimen.

Analysis of Variance↗
PubMed1996

Bezoars: implicated drugs and avoidance strategies.

A wide variety of drugs or combinations of drugs have the potential to form bezoars. In the majority of patients presenting with bezoars there is a clear predisposing factor. This article highlights those drugs or groups of drugs which have been implicated in bezoar formation. Although bezoars are rare, it is important that the clinician is aware of the possibility of their development, particularly in susceptible individuals. This is because bezoars often develop in the elderly and in those with serious coexistent disease. They may be difficult to diagnose and recourse to laparotomy is frequently required to treat them. As a result, they are associated with a significant morbidity and mortality.

Bezoars↗
PubMed1995

Post natal development of canine caudal cervical vertebrae.

The morphology and post natal ossification of the fifth, sixth and seventh cervical vertebrae of 51 crossbred puppies (aged from birth to 12 weeks) were examined grossly, histologically and radiographically. At birth there were two centres of ossification, one in the vertebral body and one in the base of each pedicle of the neural arch. By one month of age secondary centres of ossification were present in the cranial and caudal epiphyses of the vertebral body. By two months of age these epiphyseal centres began to show signs of closure. Endochondral ossification of the neural arch occurred from a single centre of ossification within each pedicle with bony fusion of the laminae occurring by one month of age. In addition the dimensions of the neural canal were measured. The difference between the caudal and cranial sagittal diameters of each vertebra was 1 mm or less. It was concluded that, after one month of age, the shape of the neural canal can be influenced only by changes within the physes between the vertebral body and the neural arch or by the remodelling of bone formed by intramembranous ossification.

Animals↗
PubMed1993

Formulation design of acidic fibroblast growth factor.

The design of an aqueous formulation for acidic fibroblast growth factor (aFGF) requires an understanding of the type of compounds that can either directly or indirectly stabilize the protein. To this end, spectrophotometric turbidity measurements were initially employed to screen the ability of polyanionic ligands, less specific compounds, and variations in solution conditions (temperature and pH) to stabilize aFGF against heat-induced aggregation. It was found that in addition to the well-known protection of aFGF by heparin, a surprisingly wide variety of polyanions (including small sulfated and phosphorylated compounds) also stabilizes aFGF. These polyanionic ligands are capable of raising the temperature at which the protein unfolds by 15-30 degrees C. Many commonly used excipients were also observed to stabilize aFGF in both the presence and the absence of heparin. High concentrations of some of these less specific agents are also able to increase the temperature of aFGF thermal unfolding by as much as 6-12 degrees C as shown by circular dichroism and differential scanning calorimetry. Other compounds were found which protect the chemically labile cysteine residues of aFGF from oxidation. Aqueous formulations of aFGF were thus designed to contain both a polyanionic ligand that enhances structural integrity by binding to the protein and chelating agents (e.g., EDTA) to prevent metal ion-catalyzed oxidation of cysteine residues. While room-temperature storage (30 degrees C) leads to rapid inactivation of aFGF in physiological buffer alone, several of these aFGF formulations are stable in vitro for at least 3 months at 30 degrees C. Three aFGF topical formulations were examined in an impaired diabetic mouse model and were found to be equally capable of accelerating wound healing.

3T3 Cells↗
PubMed1991

The structure of human acidic fibroblast growth factor and its interaction with heparin.

The secondary and tertiary structure of recombinant human acidic fibroblast growth factor (aFGF) has been characterized by a variety of spectroscopic methods. Native aFGF consists of ca. 55% beta-sheet, 20% turn, 10% alpha-helix, and 15% disordered polypeptide as determined by laser Raman, circular dichroism, and Fourier transform infrared spectroscopy; the experimentally determined secondary structure content is in agreement with that calculated by the semi-empirical methods of Chou and Fasman (Chou, P. Y., and Fasman, G. C., 1974, Biochemistry 13, 222-244) and Garnier et al. (Garnier, J. O., et al., 1978, J. Mol. Biol. 120, 97-120). Using the Garnier et al. algorithm, the major secondary structure components of aFGF have been assigned to specific regions of the polypeptide chain. The fluorescence spectrum of native aFGF is unusual in that it is dominated by tyrosine fluorescence despite the presence of a tryptophan residue in the protein. However, tryptophan fluorescence is resolved upon excitation above 295 nm. The degree of tyrosine and tryptophan solvent exposure has been assessed by a combination of ultraviolet absorption, laser Raman, and fluorescence spectroscopy; the results suggest that seven of the eight tyrosine residues are solvent exposed while the single tryptophan is partially inaccessible to solvent in native aFGF, consistent with recent crystallographic data. Denaturation of aFGF by extremes of temperature or pH leads to spectroscopically distinct conformational states in which contributions of tyrosine and tryptophan to the fluorescence spectrum of the protein vary. The protein is unstable at physiological temperatures. Addition of heparin or other sulfated polysaccharides does not affect the spectroscopic characteristics of native aFGF. These polymers do, however, dramatically stabilize the native protein against thermal and acid denaturation as determined by differential scanning calorimetry, circular dichroism, and fluorescence spectroscopy. The interaction of aFGF with such polyanions may play a role in controlling the activity of this growth factor in vivo.

Algorithms↗
PubMed1978

Methods to improve the health of cattle in the tropics: immunisation and chemoprophylaxis against haemoparasitic infections.

A study of methods to improve the health of native cattle in tropical areas of Colombia showed an advantage using immunisation techniques against haemoparasitic infections in comparison with other control methods. The control of anaplasmosis and babesiosis by immunisation of cattle with fully virulent Anaplasma marginale, Babesia argentina and B. bigemina is feasible in tropical cattle when the postimmunisation reaction is controlled by appropriate drug therapy. Chemoprophylaxis was found less effective in controlling haemoparasitic diseases; however, treated was found less effective in controlling haemoparasitic diseases; however, treated cattle surviving the acute stage of infection showed weight gains not significantly different from those of the immunised calves. Both methods were found to be advantageous with calves born and raised in an endemic area of anaplasmosis and babesiosis. Tick and gastrointestinal parasitic control without haemoparasitic control in calves had an advantage over no control system at all. These methods though were inferior to the immunisation and chemoprophylactic techniques.

Anaplasmosis↗