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Biomedical subjects

K Arnold

Publications and source records attributed to K Arnold.

At least 163 records · Page 9Linked to original sources
PubMed1989

Tetrachromatic color vision in the goldfish becomes trichromatic under white adaptation light of moderate intensity.

Spectral sensitivity of the goldfish was measured under white room light of 5 lx and 1.5 lx illuminance, using a behavioral training technique. Compared with the result obtained under 25 lx (Neumeyer, 1984), the functions differed remarkably in the mid- and longwave spectral ranges. Under 1.5 lx, the longwave maximum was absent, and wavelength discrimination was impossible in the mid- and longwave range (between 555 and 663 nm). This indicates that the longwave cone type does not contribute to color vision in these conditions. Since discrimination ability was not affected in other spectral ranges, we conclude that color vision is trichromatic then, being subserved by the ultraviolet, the short- and the midwave cone types only. Under 5 lx, the longwave cone type contributes to color vision, but, as shown in color mixture experiments, to a lesser extent.

Adaptation, Ocular↗
PubMed1989

Characterization of chemical modifications of surface properties of low density lipoproteins.

Low density lipoproteins (LDL) were modified by incubation with formaldehyde and malondialdehyde and by autoxidation. Different methods were developed to measure alterations of surface properties of LDL. A method based on fluorescamine fluorescence was used to measure changes of free amino groups. All modified LDL samples have a decreased number of amino groups. As shown by gel electrophoresis, the negative surface charge of LDL increases. Aggregation of LDL induced by poly(ethylene glycol) (PEG) is influenced by LDL modification. The PEG 6000 concentration necessary for LDL aggregation is shifted to higher values for modified LDL due to the increased negative surface charge. This result may be of interest for the application of PEG for selective separation of different classes of lipoproteins. The formation of aggregates of LDL induced by dextran sulphate is reduced due to the loss of positive charges of amino groups on the LDL surface.

Dextran Sulfate↗
PubMed1989

[Treatment of the patient with multiple trauma and prognostic assessment of the follow-up course].

After a short view of literature demands of treatment of multiple seriously injured patients, some ideas to optimize their attending are discussed. A practicable method of prognostication for critical injured patients is presented in 40 cases. It could be reached a real rating, nobody who survived was classified in the group with unfavourable prognosis. Existing problems of gradation are explained.

Adolescent↗
PubMed1989

[Ergotherapy in finger and middle hand fractures].

The value of ergotherapy (ET) was examined again. Two groups of patients were compared. 223 patients-treated with and 344 patients-attended without ET. It could be shown, that ET reduce the disablement in cases of fractures of metacarpalia and phalanges 1. In all cases with ET is the function of the injured hand something better and the rehabilitation more extensive. This could be underlined to, by measurement of ADUK.

Adolescent↗
PubMed1989

[Stepladder accidents--a 5-year analysis of these falls from a height].

156 injuries by a stepladder are reported. In the whole of plunge injuries occurred with a stepladder we found 12%. The painters are involved in 34.6% in this kind of accident, apprentices in 5.8%. Most people were aged from 20-24 and the lower limb was more often injured than the upper limb. Fractures were present in 24% and we registered 48.8 days in which workers were unfit to work. Most patients (95.2%) obtained total rehabilitation.

Absenteeism↗
PubMed1988

Interaction of electrically charged drug molecules with phospholipid membranes.

Model membranes (egg-yolk PC liposomes) were exposed to the cationic form of amphiphilic drugs. Microelectrophoresis was used to measure the change of the electrokinetic potential as a function of the drug concentration. By use of the Gouy-Chapman theory the surface potential and surface charge density were calculated. A theoretical model postulating a simple partition equilibrium of the charged drug molecules between the membrane and the aqueous phase in the vicinity of the membrane failed to describe the experimental results. Modification of the partition law by introducing a mechanism of saturation at high drug concentrations, however, resulted in concordance of model and experiment. Some parameters of the model can be used as a means of evaluating the efficiency of neuroactive drugs.

Alprenolol↗
PubMed1988

Double-blind dose finding study of mefloquine-sulfadoxine-pyrimethamine in children with acute falciparum malaria.

Three different doses of a combination of mefloquine-sulfadoxine-pyrimethamine (MSP), given double-blind as a single dose to 60 children, were evaluated for efficacy and tolerance. The children, 42 boys and 18 girls aged between 5 and 15 years, received a mefloquine dose equivalent to 1, 1.5, or 2 standard MSP (Fansimef) tablets. Radical cure was obtained in all patients with only mild to moderate side effects of nausea and vomiting, which were not worse in the higher dose groups. For children living in an endemic malarious area, a single dose of mefloquine 7.1-12.5 mg/kg, given in combination with sulfadoxine (14.3-25.0 mg/kg) and pyrimethamine (0.7-1.3 mg/kg), is a safe and effective treatment for uncomplicated chloroquine-resistant Plasmodium falciparum malaria. This dose of MSP is approximately 10 mg/kg, 20 mg/kg and 1.0 mg/kg respectively of mefloquine, sulfadoxine and pyrimethamine, which is equivalent to a single standard tablet of Fansimef (mefloquine, 250 mg; sulfadoxine, 500 mg; pyrimethamine, 25 mg) given to a child weighing 20-30 kg.

Adolescent↗
PubMed1988

Aggregation of human plasma low density lipoproteins by means of poly(ethylene glycol).

The aggregation of LDL induced by PEG was investigated by turbidity measurements at increasing concentration of PEG. Aggregation occurs over a narrow range of PEG concentration. The PEG concentration required to induce aggregation is shifted toward lower values as the LDL concentration is increased, the molecular weight of PEG is increased, the pH is decreased, and positively charged molecules such as chlorpromazine are added. The results are compared with the properties of the aggregation of proteins and liposomes. The data are interpreted on the basis of the volume exclusion principle and assuming the exclusion of PEG from the LDL surface. The influences of pH and the change of the surface charge on aggregation can be explained by the analysis of the repulsive and attractive forces.

Humans↗
PubMed1987

Wavelength discrimination in the turtle Pseudemys scripta elegans.

Wavelength discrimination was measured with two individuals using a behavioral training technique. The delta lambda function has three minima, indicating best discrimination at 400, 510 and at 570 nm (S2) or 600 nm (S1). In the range between 450 and 510 nm the ability to discriminate wavelengths was absent. This can be explained by the filter effect of the colored oil droplets, as indicated by a model computation. Color mixture experiments revealed that the high discrimination ability at 400 nm is based on an ultraviolet sensitive photoreceptor which is the fourth cone type involved in turtles' color vision. Spectral sensitivity in the ultraviolet region (measured for one turtle) is maximal at 370-380 nm.

Animals↗
PubMed1987

Electromyographic analysis of knee exercises in healthy subjects and in patients with knee pathologies.

Little information exists about the intensity of contraction required from knee and hip musculature during common therapeutic exercises used for patient populations. This study, therefore, was designed to compare electromyographic data obtained from the vastus medialis, rectus femoris, gluteus medius, and biceps femoris muscles during maximally resisted straight-leg-raising (SLR) exercises with EMG data obtained from the same muscles during quadriceps femoris muscle setting (QS) exercises in healthy subjects and in patients with knee pathologies. Of the 30 participants in the study, 16 had a history of knee injury or surgery. All participants performed randomly ordered trials of the SLR and QS exercises while the EMG data were recorded from surface electrodes and normalized to values derived from maximal effort isometric contraction trials. An analysis of variance demonstrated significantly greater activity (p less than .05) of the vastus medialis, biceps femoris, and gluteus medius muscles during QS exercises than during SLR exercises. The rectus femoris muscle was significantly more active (p less than .05) during SLR exercises than during QS exercises. The study demonstrated remarkably different degrees of muscle activation between the SLR and QS exercises, indicating that the exercise selected will affect the therapeutic intention.

Adult↗
PubMed1987

Comparative in vitro antibacterial activities of two new oral cephalosporins, ceftetrame (Ro 19-5247) and cefetamet (Ro 15-8074).

The in vitro activities of two new oral cephalosporins, ceftetrame (Ro 19-5247) and cefetamet (Ro 15-8074), were tested against 990 clinical bacterial isolates in comparison with that of cephalexin. Both compounds were more active than cephalexin against gram-negative bacteria, inhibiting most isolates of the family Enterobacteriaceae at concentrations of less than or equal to 4 micrograms/ml, but were not active against Acinetobacter species, most Pseudomonas species, Campylobacter jejuni, and Flavobacterium meningosepticum. Ceftetrame was also more active than cephalexin against most streptococcal isolates and as active as cephalexin against methicillin-susceptible Staphylococcus aureus; against the latter cefetamet was ineffective.

Bacteria↗
PubMed1987

Alterations of surface charges of plasma lipoproteins in ischemic heart disease.

For a charged and an uncharged long chain spin probe the partition between the aqueous phase and the lipoproteins LDL, HDL2 and HDL3 was measured by use of ESR spectroscopy. The partition coefficients were compared for lipoproteins from normal donors and lipoproteins from patients with ischemic heart disease. The partition coefficients of the uncharged spin probe are not different. However, the charged spin probe has a significantly different partition for LDL and HDL3. This difference results from changes in the surface charge. Patients with ischemic heart disease have LDL which is more electropositively charged and HDL3 is more electronegatively charged compared to the corresponding lipoproteins of normal subjects. The surface charge of HDL2 is not changed. The results are discussed in the light of current concepts of the pathogenesis of atherosclerosis.

Coronary Disease↗
PubMed1986

The rate of lateral diffusion of phospholipids in erythrocyte microvesicles.

31P-NMR spectra of phospholipids in membranes of erythrocyte microvesicles isolated from outdated blood units were recorded in the temperature range 5 to 55 degrees C. Within that range the lineshape is strongly influenced by an increasing rate of lateral diffusion of phospholipids. At 36 degrees C a diffusion constant, D, of (2 +/- 1) X 10(-12) m2/s was obtained. The diffusion rate is by a factor of 3 to 10 greater than in erythrocyte membranes measured by the photobleaching technique and is comparable with values obtained for several lipid model membranes. The differences in lateral diffusion rates are probably connected with the depletion of microvesicle membranes in membrane proteins.

Blood Viscosity↗