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Biomedical subjects

K Scott

Publications and source records attributed to K Scott.

At least 19 recordsLinked to original sources
PubMed1992

Reactor modelling for electrochemical processes.

This paper presents a relatively straightforward approach to the modelling of electrochemical reactors operated in batch or continuous modes. The models are based on ideal flow assumptions of either well-mixed or plug flow and incorporate reaction rate models based on electrochemical kinetics and mass transport at one electrode. General characteristics of the reactor models are described, particularly with regard to the need for good mass transport in metal recovery applications. An example is given on the use of the model in the recovery of a heavy metal (Cd2+) from an acidified solution containing Cd(II) and Fe(III) ions. The reaction rate model is based on experimental data.

Cadmium↗
PubMed1992

Enzymatic activity and immunoreactivity of extracellular phospholipase A2 in inflammatory synovial fluids.

Synovial fluid PLA2 concentration was measured by an ELISA technique using monoclonal antibodies raised against human recombinant "synovial-type" group II phospholipase A2. This ELISA was specific for synovial-type PLA2 and did not detect pancreatic (group I) PLA2. In all synovial fluids examined, including rheumatoid, osteoarthritic, psoriatic, and gouty fluids, synovial fluid PLA2 enzyme activity significantly correlated with PLA2 immunoreactivity (P < 0.001). Within the limits of the ELISA technique, there was no evidence for the presence of specific or nonspecific modulation of PLA2 activity by either putative PLA2 activating or inhibitory proteins.

Arthritis↗
PubMed1992

Serum phospholipase A2 enzyme activity and immunoreactivity in a prospective analysis of patients with septic shock.

Massive elevations of serum phospholipase A2 activity have been documented in patients with septic shock. Serum PLA2 activity correlated to the degree and duration of circulatory collapse, while purified native PLA2 reproduced hypotension in experimental animals. In a prospective study of patients with septic shock, we have determined the relationship of PLA2 enzyme activity to PLA2 immunoreactivity using radiolabelled E. coli phospholipid substrate and an ELISA specific for group II human nonpancreatic PLA2. In all patients, there was a clear concordance of the two assays. Maximal PLA2 concentration was increased a mean of 554-fold over normal levels. We found no evidence to support the presence of activating or inhibitory proteins. These data confirm that the observed increase in serum PLA2 activity in septic shock is due to intravascular release of group II nonpancreatic PLA2.

Antibodies, Monoclonal↗
PubMed1992

Induction of circulating group II phospholipase A2 expression in adults with malaria.

High levels of interleukin 1 and tumor necrosis factor are found in both cases of malaria and cases of septic shock. Since both interleukin 1 and tumor necrosis factor induce expression of the proinflammatory enzyme phospholipase A2 (PLA2), we examined serum PLA2 levels in 14 adults with malaria. Mean serum PLA2 activity was elevated 40-fold above normal (P less than 0.001). Serum PLA2 activity correlated with PLA2 immunoreactivity (r = 0.987; P less than 0.001) by an enzyme-linked immunosorbent assay specific for human group II PLA2, showing that serum PLA2 in cases of malaria is host derived. This article describes the novel finding of elevated PLA2 levels in cases of malaria, further strengthening the notion that mediators of the host response in cases of malaria are similar to those in cases of septic shock.

Adult↗
PubMed1989

Efficacy of a multivalent Bacteroides nodosus vaccine against foot rot in sheep in Britain.

A multivalent Bacteroides nodosus foot rot vaccine was tested by comparing the prevalence of foot rot in 317 vaccinated ewes and lambs with the prevalence in 422 unvaccinated control sheep. The vaccine conferred statistically significant protection against foot rot. The vaccine also demonstrated a therapeutic effect in animals with foot rot, after one injection.

Animals↗
PubMed1989

The use of band-selectable digital filtering in magnetic resonance image enhancement.

Manipulation of the data describing two-dimensional magnetic resonance (MR) images can be used to zoom an image, decrease image noise and artifacts by modeling, or emphasize object edges in the field of view. In this paper, a two-dimensional band-selectable digital filtering (2D-BSDF) technique is detailed. This can be used to decrease the computational burden and increase algorithm stability associated with such data manipulation. Many display devices have the ability of expanding an image by pixel or linear interpolation. Application of the efficient zooming fast Fourier transformation algorithms provides a superior quality sinc-function interpolated image. In 2D-BSDF, the ideal rectangular windows used in sinc-function interpolation are replaced by windows with a more gradual roll-off. This gradual roll-off results in a slight degradation of the image edges but substantially reduces the computation time. Modeling of MRI data has been attempted to remove noise and artifacts from the image. These algorithms are computationally expensive and frequently unstable because of the high model orders required. The 2D-BSDF can be used to prepare a reduced data set, without loss of information. A lower order model may be applied to the subset and computation times approaching that required for normal fast Fourier transform algorithms result. The absence of noise and signal from objects outside the region of interest can considerably enhance the stability of the modeling algorithms. The use of BSDF is equally applicable when used in association with the modeling of 2D NMR spectroscopy data or with edge enhancement or any other data manipulation of magnetic resonance imaging images. In this paper an explanation of 1D-BSDF is provided and an algorithm for 2D-BSDF is developed. A comparison of filter designs and computational times is given when applying the technique to zooming and modeling of MR images. Images from medical MRI data are provided.

Algorithms↗
PubMed1989

Prenatal cocaine exposure to the fetus: a sheep model for cardiovascular evaluation.

Transplacental passage of cocaine in response to maternal administration of intravenous (IV) cocaine in doses of 1.0 and 2.0 mg/kg was studied in 6 pregnant ewes and fetuses and correlated with maximum changes in maternal and fetal blood pressures (BP), heart rates (HR) and fetal arterial blood gas values. Certain animals were given larger doses (3.0 and 5.0 mg/kg) of cocaine to examine cocaine-related cardiopulmonary and neurologic sequelae. Cocaine was extracted on C-18 sorbent columns and analyzed by gas chromatography. At 1.0 and 2.0 mg/kg, cocaine produced dose-dependent increases in maternal HR and BP which were maximum by 1 minute. The fetal response was characterized by maximum increases in BP and decreases in PO2 by 3 minutes and increases in HR by 15 minutes. Cocaine rapidly appeared in the fetal circulation, was approximately 15% of maternal concentrations by 5 minutes, and was undetectable in both circulations by 60 minutes. At cocaine doses of 3.0 and 5.0 mg/kg significant maternal cardiopulmonary and neurologic complications were encountered including bradyarrhythmias, respiratory distress, seizure and death. These data indicate that cocaine exerts direct drug actions upon maternal cardiovascular and neurologic function. In addition, cocaine affects fetal cardiovascular function directly via transplacental passage and indirectly by fetal hypoxemia from cocaine-induced uterine artery vasoconstriction. (NIDA 04415)

Animals↗
PubMed1987

Randomized, double-blind, cross-over study comparing prochlorperazine and lorazepam with high-dose metoclopramide and lorazepam for the control of emesis in patients receiving cytotoxic chemotherapy.

To further define optimal combinations of antiemetics, high-dose metoclopramide and lorazepam (M+L) were compared with prochlorperazine and lorazepam (P+L) in a randomized, double-blind, cross-over study. Both patient and observer assessments were documented in 66 patients receiving cisplatin and noncisplatin chemotherapy. M+L significantly reduced the severity of vomiting (P = 0.01), duration of vomiting (P = 0.05), and number of vomiting episodes (P = 0.003). Comparing the severity or duration of nausea, M+L and P+L were not significantly different. M+L significantly reduced severity of vomiting (P = 0.005) and number of vomiting episodes (P = 0.03) in the cisplatin subset. The number of vomiting episodes was also reduced in the noncisplatin subset (P = 0.03). When asked to nominate a preferred regimen, 41% of patients preferred P+L, 35% preferred M+L, and 24% rated them equally. M+L was associated with significantly more anxiety and less sedation than P+L. Patient assessments produced similar results to observer assessments but gave a broader understanding of our patients' tolerance to chemotherapy. M+L is a superior regimen in controlling vomiting induced by chemotherapy.

Adult↗
PubMed1986

Three-year prospective study of HTLV-III/LAV infection in homosexual men.

170 symptom-free homosexual men were recruited in London in 1982-83 and 133 were evaluable in 1983-85. Of the 33 who were seropositive to HTLV-III/LAV at entry, 4 (12%) progressed to AIDS, 16 (48%) progressed to persistent generalised lymphadenopathy (PGL), and 13 (40%) remained symptom-free. A further 15 men seroconverted during the study (7% per annum), of whom 8 progressed to PGL. Serial estimations of T lymphocyte subsets showed progressive reduction in T4 numbers in the seropositive groups, but these indices also varied widely in the seronegative group. Counts of T4 and T8 cells or T4/T8 ratio at entry were not of prognostic value. Seronegative subjects were as likely as seropositives to have abnormal immunological tests. Serial measurement of T lymphocyte subsets seems to be of little prognostic or clinical value in the monitoring of populations infected with the HTLV-III/LAV virus. The strongest association with prognosis was an episode of sexually transmitted disease in the six months before entry to the study. This supports the hypothesis that intercurrent infection may be an important co-factor in the acquisition of HTLV-III/LAV infection, and in subsequent disease progression.

Acquired Immunodeficiency Syndrome↗
PubMed1976

Purification and properties of a carboxylesterase from the liver of tiger shark (Galeocerdo cuvier).

A procedure is described for the purification of a carboxylesterase from shark liver, using a chloroform-acetone powder prepared from the liver as the starting material. The yield of purified enzyme is approximately 50 mg from 530 g of chloroform-acetone powder. The preparation is electrophoretically homogeneous. Active-site titrations with paraoxon gave an equivalent weight of approximately 83 000. The molecular weight, found from sedimentation equilibrium experiments, is approximately 80 000. There is no evidence of any association or dissociation of this species. The enzyme shows a marked preference for aryl esters over alkyl esters, in contrast to other carboxylesterases so far studied. The amino acid composition of the purified enzyme is reported.

Amino Acids↗
PubMed1976

Pathology of chronic Bolivian hemorrhagic fever in the rhesus monkey.

Gross and microscopic lesions of Bolivian hemorrhagic fever (BHF) are described in 10 rhesus monkeys that survived from 30 to 78 days after subcutaneous inoculation with a dose of 10(3) plaque-forming units (PFU) of Machupo virus, a dose which produces a severe and generally fatal disease. Six of the monkeys had been given low doses of homologous immune globulin when initial signs of infection appeared. Monkeys exhibited clinical signs in two phases. The initial signs of acute infection which began to appear about 1 week following inoculation included: diarrhea, depression, anorexia, dehydration, and skin rash. The survivors of this early phase of the illness usually showed improvement before relapsing into the second (or chronic) phase, which was characterized clinically by central nervous system disturbances including incoordination, tremors, convulsions, paresis, and muscle atrophy. Microscopic lesions were similar in both immune globulin-treated and untreated animals. These included widespread lymphoreticular infiltrates in the walls and adventitia of blood vessels of the brain, spinal cord, pancreas, intestine, liver kidney, adrenal, parathyroid, heart, and skeletal muscle. Diffuse lymphocytic infiltrates not confined to the vascular or perivascular tissues were present to a variable degree in many of these and other organs. Several monkeys exhibited lymphocytic inflammation of the choroid, meninges, peripheral nerves, and ganglia.

Adrenal Glands↗
PubMed1975

Carboxylesterases (EC 3.1.1). Purification and titration of chicken, sheep, and horse liver carboxylesterases.

Chicken, sheep, and horse liver carboxylesterases have been purified by procedures involving ammonium sulfate fractionation, ion-exchange chromatography and gel filtration on Sephadex. The actual yields of the procedures described were as follows: chicken, 1 g from 2 kg of liver powder (chloroform-acetone); sheep, 200 mg from 400 g of powder (chloroform-acetone); horse, 230 mg from 800 g of powder (acetone). The purified enzymes are free of non-carboxyl-esterase protein as shown by gel electrophoresis, although they do contain electrophoretic variants. The equivalent weight of the chicken enzyme is 67,000 based on titration with p-nitrophenyl diethyl phosphate or bis(p-nitrophenyl) phosphate, whereas those of the sheep and horse enzymes are similar to 69,500 and similar to 70,000, respectively, based on titration with p-nitrophenyl dimethylcarbamate.

Ammonium Sulfate↗