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At least 847 records · Page 47Linked to original sources
PubMed1990

Effect of atrial natriuretic peptide on ischaemic brain oedema.

We investigated the effect of intraventricularly administered atrial natriuretic peptide (ANP) on the brain water, sodium and potassium contents in ischaemic brain oedema. Global ischaemia (15 min) followed by recirculation (30 min) produced by a three vessel occlusion in the rat served as a model for induction of ischaemic cerebral oedema. Water content was measured by a drying-weighing method. Sodium and potassium contents were measured by means of flame photometry. The effect of ANP was evaluated by comparing these parameters of the ANP-treated group (5 micrograms/kg and 10 micrograms/kg atriopeptin) with those of the control group (administration of 0.9% NaCL). ANP did not significantly change the content of water, sodium and potassium in the preischaemic or ischaemic brain. Intraventricularly administered ANP (5 micrograms/kg and 10 micrograms/kg) caused significant decrease in the brain water (p less than 0.02) and sodium (p less than 0.01) contents after 15 min of ischaemia and 30 min of recirculation, while the brain potassium content remained unaltered. Serum osmolality, and sodium and potassium concentrations were not influenced by administration of ANP. Accordingly, ANP acts directly on the central nervous system to inhibit brain water and sodium accumulation in ischaemic brain oedema.

Animals↗
PubMedDate not supplied

Effects of subconjunctival methylprednisolone on the blood aqueous barrier following cataract surgery.

The aim of this double-blind randomized study was to assess the effect of subconjunctival methylprednisolone hemisuccinate (MH) on the recovery of the blood aqueous barrier (BAB) following uncomplicated cataract surgery performed by the same surgeon in normal eyes. Fifty eyes of fifty patients (28 female, 22 male, mean age 72.3 +/- 11.2 years) were randomized into two groups: group 1 received a subconjunctival injection of MH (40 mg in 0.5 cc) at the end of the surgery and group 2 did not. All patients were free of other ocular or systemic diseases known to alter the BAB and were not taking any anti-inflammatory medications. Postoperative treatments were similar in both groups. The patients were submitted to laser flare photometry 30 minutes to one hour after mydriasis with a drop of tropicamide preoperatively and on the first, second and seventh day and then one month and six months following surgery. No difference in aqueous flare was seen between the two groups on any of postoperative visits. These data suggest that subconjunctival MH has no beneficial effect in postoperative BAB permeability following uncomplicated cataract surgery in normal eyes.

Aged↗
PubMed1996

[Hepatic encephalopathy after portosystemic shunt].

A total of 28 cirrhotic patients with porto-systemic anastomosis were compared with 38 cirrhotic patients without porto-systemic shunts concerning their mental state and biochemical parameters of importance for hepatic encephalopathy. A group of 37 metabolically healthy individuals provided the reference values for the psychometric test results and the EEG power spectra. Laboratory values for both groups showed marginal elevation of bilirubin, while the ammonia levels were significantly increased in the operated group. A significant difference was found concerning both the tyrosine level and that of the branched-chain amino acids. None of the patients who had surgical treatment showed clinical evidence of hepatic encephalopathy. Regarding the results in the flicker photometry, the non-shunted cirrhotic patients differed significantly from the healthy control subjects. For both the shunted and non-shunted cirrhotic patients, the results of the Viennese determination test and the number connection test indicated subclinical encephalopathy. We conclude that the elevated ammonia level in patients with porto-systemic anastomosis does not cause a significant mental disturbance. In well-selected patients, the porto-systemic end-side shunt is an appropriate procedure in the treatment of esophageal varices.

Adult↗
PubMed1985

A sensitive and simple assay of saliva on stamps.

Identification of saliva on stamps or envelope flaps remains yet a not widely studied problem. In most forensic laboratories it is seldom carried out, but this fact does not reduce the importance of the assay. Most authors consider amylase a sufficiently specific marker of the presence of saliva; really, the only other human body fluid that contains high amounts of this enzyme is the pancreatic juice (and therefore feces). Here we present a simple and sensitive assay for the determination of alpha-amylase that uses a commercially available and well-known substrate. It is hydrolyzed by amylase with the production of soluble blue fragments, that can be measured by photometry, obtaining objective results. The presented assay identifies 1 X 10(-6) diluted saliva or that present on 0.5 mg of a stamp; 16-year-old samples can also be identified. Intra-assay and day-to-day CV resulted in 10.8% and 13.7%, respectively. Owing to the high sensitivity of the test, handling samples or reagents can introduce contamination with saliva traces, giving false-positive results. Addition of EDTA 0.1 mol/l to the incubation mixture, lowering the sensitivity to 1 X 10(-3) diluted saliva, overcomes this problem.

Amylases↗
PubMed1995

Nystatin-, mycoheptin- and levorin-induced conductance in the membrane of frog skeletal muscle fibres.

The effects of the polyene antibiotics nystatin (2 x 10(-5)-10(-4) mol/l), mycoheptin (1.3 x 10(-6)-10(-5) mol/l) and levorin (10(-8)-5 x 10(-5) mol/l) on isolated frog skeletal muscle fibres and whole sartorius muscles of the frog have been investigated. Cation conductance was measured under current clamp conditions using a double sucrose-gap technique. Cation effluxes were studied by means of flame emission photometry. All three antibiotics increased the cation conductance and efflux rates; however, differences between the polyenes were found in the steady state values of induced cation transport at a given concentration. The values of both induced conductance gA infinity and efflux rate constants KA formed the following sequence: levorin > mycoheptin > nystatin, demonstrating a correlation with the order of antifungal activities. The dose-response curves of lg polyene-induced cation transport against lg of antibiotic concentration in our experiments had slope values which were much lower than those in bilayers: 1.7 and 1.3 for nystatin and mycoheptin, respectively, whereas the aromatic heptaene levorin had an even smaller concentration dependence. The decline in the equilibrium conductance caused by nystatin- and mycoheptin removal was very fast (during the first minute tau = 0.74 and 2.39 min, respectively). In contrast, levorin-induced conductance was irreversible. It is proposed that the processes which limit the rate of channel formation are different in biological and model membranes.

Animals↗
PubMed1992

Cone photopigments in nocturnal and diurnal procyonids.

Procyonids are small, New World carnivores distributed among some 6 genera. Electroretinogram (ERG) flicker photometry was used to measure the spectra of the cone photopigments for members of two nocturnal species, the raccoon (Procyon lotor) and the kinkajou (Potos flavus), and a diurnal species, the coati (Nasua nasua). Each of the 3 has a class of cone photopigment with maximum sensitivity in the middle to long wavelengths. The spectral positioning of this cone is different for the three. Whereas the raccoon and kinkajou are monochromatic, the diurnal coati is a dichromat having an additional class of cone photopigment with peak sensitivity close to 433 nm.

Animals↗
PubMed1979

Water compartments in living, glycerinated and fixed skeletal muscles of the frog.

The kinetics of water replacement with heavy water (deuterium oxide) in the gastrocnemius and sartorius muscles of the frog under isotonic conditions, studied both gravimetrically and by infrared photometry, reveals three water compartments: (i) non-exchangeable (approximately 80 ml/kg fresh weight), (ii) slowly exchanging (approximately 500 ml/kg fresh weight), (iii) rapid exchanging--extracellular (approximately 200 ml/kg fresh weight). Exposure to both glycerol and glutaraldehyde increases the permeability coefficients and the amount of rapid exchanging water; glutaraldehyde also increases the amount of non-exchangeable water. Approximately 90% of the water is kept in the tissue only by weak intermolecular forces, the energies of which amount to 1 kcal/mol. The amount of non-exchangeable water is equivalent to about six continuous adsorption layers covering the myofilaments. Approximately 70% of the tissue water appears to be replaced by glutaraldehyde during standard fixation.

Aldehydes↗
PubMed1985

Electrolyte levels in the CSF of children with nontumoral hydrocephalus. Relation to clinical parameters.

The levels of calcium and magnesium (by atomic absorption spectrophotometry), sodium and potassium (by flame photometry), inorganic phosphate and proteins (by spectrophotometry) were measured in the CSF of 27 children with hydrocephalus and compared with the CSF data on 10 controls, so as to study the effect of the blood-brain and blood-CSF barrier alterations observed in hydrocephalus, on the CSF electrolytes. Ca (P less than 0.001), Mg (P less than 0.01) and phosphate (P less than 0.05) were found to be increased, K (P less than 0.01) decreased, and Na levels not significantly altered. Linear regression analysis of hydrocephalic patients showed a linear correlation (r = +0.62) between phosphate and proteins (P less than 0.01) and (r = +0.66) between phosphate and Ca (P less than 0.001). Comparison of control CSF electrolyte levels with those found in the CSF of hydrocephalic patients were grouped according to clinical variables: sex (F, M), age (less than or equal to 1.5 months, greater than 1.5 months), etiological variants (congenital, acquired), treated infection (no, yes), surgical treatment (no, yes), time of onset (less than or equal to 1 month, greater than 1 month), ventricular dilation (mild, severe) and intracranial hypertension (mild or severe). These comparisons showed specific increases of Mg for males (P less than 0.05), acquired hydrocephalus (P less than 0.05) and severe intracranial hypertension (ICH) (P less than 0.001), moderate decrease in the Na levels in acquired hydrocephalus (P less than 0.05) and mild ICH (P less than 0.05), specific increases of phosphate in females (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1980

Minimum phototoxicity dose (MPD). Comparison of conventional light sources and different lasers.

A pilot study was performed on groups of 5-7 volunteers to evaluate the minimum phototoxicity dose (MPD) of several light sources with different UVA qualities to optimise photochemotherapy. Visual observation was more suitable than reflection photometry in determining the threshold and gradation of erythema reactions; thermometry gave poor results. There were no individual differences between the MPD of a PUVA 4000 box and a continuously emitting argon-ion laser with 40 and 400 mW, respectively. The pulsed radiation of a nitrogen laser was the most effective. The limited validity of the Bunsen-Roscoe law for high peak power could thus be tested for a secondary photochemical reaction of the skin. The nitrogen laser (337.1 nm) proved that a repetition rate of 20 Hz was superior to 10 and 40 Hz. The MPD was intraindividually higher at 25 Hz than at 10 and 16.7 Hz for the dye laser tested (325 and 330 nm, respectively).

Dose-Response Relationship, Radiation↗
PubMed1981

[Principal possibilities and limitations of fluorescent angiographic procedures for the measurement of the flow-physical magnitudes of the retinal circulatory system (author's transl)].

Flow-physical magnitudes are presented that describe the retinal circulatory system. The principal possibilities and limitations of fluorescent angiographic procedures for the measurement of these magnitudes are discussed. On this basis, we compare fluorescentophthalmoscopic measurements of time, serial angiography, and cinematography with densitometric evaluation of the negatives, integral fluorophotometry, 'two point' photometry, and the application of television with evaluation of the video signal.

Fluorescein Angiography↗
PubMed1986

Histophotometric estimation of volume density of collagen as an indication of fibrosis in rat liver.

The development of fibrosis in the liver of 16 rats treated for 1, 2, 3 or 4 weeks with CCl4, has been followed with chemical hydroxyproline determination and histophotometric analysis of histological sections stained with Sirius Red F3BA in saturated aqueous picric acid. The readings were taken with a scanning and integrating microphotometer and corrected for picric acid absorbance as a measure for mean protein mass per unit area of the section. It appears that the integrated absorbance readings of Sirius Red absorbing material in the section show a highly significant correlation with the hydroxyproline determinations. It is concluded that picrosirius photometry can be used to give a measure of the volume density of collagen in sections. An advantage of the photometric assay is that measurements are taken on the basis of the microscopic image, so that it is also possible to estimate collagen density in a selected area, e.g. a tumour formation amidst normal tissue, or to exclude necrotic areas.

Animals↗
PubMed1987

Photoelectric recording of mechanical responses of cardiac myocytes.

A method to monitor contraction of isolated myocytes by transmicroscopic photometry is illustrated. Two photodiodes are mounted inside an inverse microscope used for visual control of a cell. Illumination of one diode varies in proportion to changes in cell length. The contraction signal is amplified in a comparator circuit. Spatial resolution of the device is in the order of 1 micron which corresponds to about 5% of cell shortening in the fully activated state of contraction. The method was tested on isolated myocytes from guinea-pig ventricle. Optical records of contraction in response to action potentials or during voltage clamp compare well with the contractile behavior of multicellular preparations.

Action Potentials↗
PubMed1977

Studies on the suitability of a cyanine dye (Viher-Test) for indicator dilution technique and its application to the measurement of pulmonary artery and aortic flow.

The spectrum of a cyanine compound [Viher-Test (VT)] was recorded in distilled water, 5% glucose, 0.9% NaCl. The absorption maximum of these solutions was at 760 nm; after adding to plasma or blood the maximum was shifted to 785 nm. The time required for this spectral stabilization was less than 1 s at 37 degrees C for VT in H2O or glucose, it was slowed to 7 s at room temperature, and for VT in NaCl it was more than 30 s at 37 degrees C. VT binds to plasma proteins to at least 95%. The absorbance of VT in H2O (1000 mg/l) decreased by 1.0% per hour. Toxicity (LD50) of VT in H2O given i.v. in mice was 115 mg/kg body weight. Dye dilution determination of the flow in an artificial circulation with VT was within +/- 5% of direct measurements. Data indicate that VT is as suitable as Cardiogreen for indicator dilution technique using cuvette densitometer or reflection photometry. Simultaneous determinations of pulmonary artery and aortic flow from one dye bolus showed no significant difference on the average, but pulmonary artery flow diverged by up to +/- 25% from aortic flow due to incomplete mixing of dye and blood, respiratory changes of cardiac output or transient differences in right and left heart output.

Animals↗
PubMed1976

Effects of Na and K ions on the active Na transport in guinea-pig auricles.

1. The effect of Na and K ions on active Na transport was studied in guinea-pig auricles by means of flame photometry. 2. The Na influx into preparations rewarmed in Tyrode's solution after cooling was estimated to be about 1.05 mmole/l fibre water - min (l.f.w.-min) or c. 8 pmole/cm2 - s. Intracellular Na ions enhanced the active Na efflux over a wide range of concentrations. A decrease in the extracellular Na concentration ([Na]o) had no major effect on the active Na efflux. 3. Extracellular K ions initiated an active Na efflux from rewarmed auricles with an elevated [Na[i over a narrow range of K concentrations ([K]o). 4. Assuming Michaelis-Menten kinetics the maximal active Na efflux activated by internal Na ions was calculated to be about 4 mmole/l.f.w. - min (30 pmole/cm2 - s). Half maximal Na efflux occurred at about 22 mmole/l.f.w. [Na]i. The maximal K-activated active - min (28 pmole/cm2 - s) and was half maximal at a [K]o of about 0.2 mM. 5. It is tentatively concluded that the maximal active Na efflux from guinea-pig atria is 3--4 times larger than the physiological flux. Under normal conditions active Na efflux in heart is mainly regulated by variations of [Na]i.

Animals↗
PubMed1994

Intracellular calcium variations evoked by mechanical stimulation of mammalian isolated vestibular type I hair cells.

The variations of intracellular free calcium concentration ([Ca2+]i) were recorded on-line from guinea-pig isolated vestibular sensory cells using a fura-2 fast fluorescent photometry system, during mechanical displacements of the hair bundle. Repetitive displacements of the hair bundle towards the kinocilium (positive stimulation 7 degrees, 300 ms, 2Hz for 10 s), revealed [Ca2+]i variations detectable only in the cuticular plate. [Ca2+]i increased from 105 to 145 nM. Single mechanical displacements of the hair bundle (7 degrees, 200 ms, 0.5 Hz) evoked increases of [Ca2+]i from 50 +/- 23 nM to 139 +/- 79 (n = 12). In the opposite direction, the mechanical stimulations (8 degrees, 400 ms, 0.5 Hz) evoked a decrease of [Ca2+]i from 68 +/- 17 nM to 37 +/- 12 nM (n = 8). The variations of [Ca2+]i detected in the cuticular plate during positive displacements of the hair bundle were reversibly abolished in the presence of 100 microM gentamicin and they could not be evoked in 0.1 mM calcium in the external medium. From these experiments, it has been concluded that the [Ca2+]i variations recorded in the cuticular plate were due to a limited entry of calcium ions through transduction channels localized in the hair bundle. The typical kinetics of variations of [Ca2+]i evoked during positive displacements of the hair bundle should account for the presence of strong calcium regulation systems in the hair bundle and cuticular plate.

Animals↗
PubMed1976

K and Na ion content in the Pacinian corpuscle fluid and its role in the activity of receptors.

1. Potassium and sodium concentrations within the Pacinian corpuscle fluid have been investigated in adult cats. The sodium and potassium contents of samples were estimated by means of integrative ultramicroflame photometry. 2. The analytical results showed the values of the potassium concentration in the Pacinian corpuscle fluid and in the blood plasma to be 6.19 +/- 0.72 and 2.78 +/- 0.38 mequiv/1, respectively. 3. The increasing excitability of the Pacinian corpuscle in potassium-rich solution was shown by electrophysiologic methods. In potassium-free solution two phases of changing receptor excitability were observed. 4. Removal of sodium from external solution reduced the receptor potential to 10% of its original value. 5. Some mechanisms of the increase in excitability of primary tissue mechanoreceptors and secondary mechanoreceptors of the sense organs are discussed.

Animals↗
PubMed1975

Microrheology and light transmission of blood. IV. The kinetics of artificial red cell aggregation induced by Dextran.

Employing both microscopic and photometric methods the rheology of pathological red cell aggregation was studied in model experiments. Suspensions of washed human red blood cells in dextran solutions containing rising concentrations of dextrans (M.W. 40000, 70000, 110000, 250000, 500000) were used. At low concentrations (less than 500 mg-%) of high molecular weight dextrans (greater than 70000) red cell suspensions formed aggregates similar to the ones found in normal human blood. At higher concentrations, the aggregates were similar to those observed in pathological human blood. The aggregates were studied under the condition of stasis, slow flow and at shear rate of their hydrodynamic dispersion. Besides, the flow behavior of the dispersed cells at high shear rates was studied. We found: 1. In all samples the rate of spontaneous aggregate re-formation in stasis (following hydrodynamic desaggregation) rose with rising dextran concentration up to 5.0 g-%. 2. The shear resistance of the aggregates, as measured by the shear stress necessary to keep them dispersed, rose up to concentrations of 2.5g-%, but fell at higher concentrations. 3. Only with dextran of a molecular weight above 110000 coarse agglomerates could be produced at high concentrations. Loose elastic meshes were rapidly produced at high concentrations of Dx 70. 4. When subjected to steady state low shear (m sec-1) only the agglomerates, but not the meshes rapidly grew in size. Most of the aggregation kinetics recorded by photometry and microscopy evaded detection by viscometry.

Blood Viscosity↗