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At least 199 records · Page 11Linked to original sources

PubMedDate not supplied

Ultrawide-band electromagnetic pulses induced hypotension in rats.

The ultrawide-band (UWB) electromagnetic pulses are used as a new modality in radar technology. Biological effects of extremely high peak E-field, fast rise time, ultrashort pulse width, and ultrawide band have not been investigated heretofore due to the lack of animal exposure facilities. A new biological effects database is needed to establish personnel protection guidelines for these new type of radiofrequency radiation. Functional indices of the cardiovascular system (heart rate, systolic, mean, and diastolic pressures) were selected to represent biological end points that may be susceptible to the UWB radiation. A noninvasive tail-cuff photoelectric sensor sphygmomanometer was used. Male Wistar-Kyoto rats were subjected to sham exposure, 0.5-kHz (93 kV/m, 180 ps rise time, 1.00 ns pulse width, whole-body averaged specific absorption rate, SAR = 70 mW/kg) or a 1-kHz (85 kV/m, 200 ps rise time, 1.03 ns pulse width, SAR = 121 mW/kg) UWB fields in a tapered parallel plate GTEM cell for 6 min. Cardiovascular functions were evaluated from 45 min to 4 weeks after exposures. Significant decrease in arterial blood pressures (hypotension) was found. In contrast, heart rate was not altered by these exposures. The UWB radiation-induced hypotension was a robust, consistent, and persistent effect.

Animals↗

PubMed1999

Ultrawide-band electromagnetic pulses induced hypotension in rats.

Animals↗

PubMed1992

Neuropeptide Y in the rabbit maxillary sinus modulates cholinergic acceleration of mucociliary activity.

The distribution of neuropeptide Y (NPY)-immunoreactivity was investigated in the rabbit maxillary sinus and adjacent ganglia. A moderate supply of NPY-containing nerve fibers occurred around seromucous glands and a denser supply around small blood vessels. Only a few immunoreactive nerve fibers were seen beneath the epithelium. Double immunostaining showed that vasoactive intestinal peptide (VIP) coexisted with NPY in the nerve fibers surrounding blood vessels and seromucous glands. NPY-containing nerve cell bodies were numerous in the superior cervical ganglion, and moderately numerous in the sphenopalatine ganglion. The finding of NPY-containing neurons in the latter parasympathetic ganglion suggests that NPY may influence the cholinergic regulation of mucociliary activity. The effect of NPY on the mucociliary activity of the maxillary sinus in connection with cholinergic stimulation has therefore been investigated in vivo using a photoelectric technique. At dosages of 2.5 and 5.0 micrograms/kg, the ganglionic stimulant nicotine bitartrate, which increases mucociliary activity by a cholinergic pathway, accelerated mucociliary activity by 28.0 +/- 7.5% and 36.8 +/- 6.2%, respectively. In the same experiment repeated during infusion of NPY (0.1 microgram/kg/min), the increase in mucociliary activity was reduced to 10.8 +/- 2.3% and 28.9 +/- 7.1%, respectively. Infusion of NPY did not affect the stimulating effect on mucociliary activity by bolus injections (0.1 and 0.5 microgram/kg) of the cholinergic agonist, methacholine. It is concluded that NPY-like immunoreactivity is present in nerve fibers in the rabbit maxillary sinus and in neurons in the sympathetic and parasympathetic ganglia that supply the nose and paranasal sinuses. NPY attenuates the effect of nicotine on mucociliary activity, probably via a prejunctional mechanism, and may act as a modulator of cholinergic regulation of the mucociliary system.

Animals↗

PubMedDate not supplied

[Quantum-mechanical model of the genesis of the early receptor potential in the retina].

An account is given of a possible mechanism of the initiation of the retina early receptor potential due to quantization of the electron energetic spectrum in its fine biolayers. A connection is established between the fine structure of lamellar systems of biological origin and function. The mechanism suggested can be used when studying photoelectric processes in chlorophyll layers, in beta-carotin films for the search of means to increase the photopotential value in the films of photosynthetic pigments, when explaining the receptors adaptation property.

Mathematics↗

PubMed1997

Photoelectric properties of chlorophyll and carotene solutions in nematic liquid crystal located between semiconducting electrodes.

The photopotential and photocurrent generation for chlorophyll a, beta-carotene and a mixture of these pigments dissolved in nematic liquid crystal and located between transparent semiconducting electrodes were measured. Both pigments exhibit photopotential and photocurrent generation. From the photocurrent amplitudes it follows that the efficiency of electron transfer to a semiconducting electrode from beta-carotene is higher than from chlorophyll alpha. The photocurrent amplitude of the pigment mixture is slightly lower than that calculated as a sum of amplitudes of pigments located in separated cells. This difference can be explained by secondary effects, such as competition between carotene and chlorophyll molecules in a process of adsorption on a semiconducting electrode. Therefore it seems that no charge transfer complexes of chlorophyll and carotene are formed in the investigated model system.

Journal Article↗

PubMed1991

Vasoactive intestinal peptide stimulates ciliary motility in rabbit tracheal epithelium: modulation by neutral endopeptidase.

We studied the effect of vasoactive intestinal peptide (VIP) on ciliary activity in rabbit cultured tracheal epithelium by a photoelectric method in vitro. Administration of VIP (10(-7) M) elicited an increase in ciliary beat frequency (CBF) from the baseline values of 970 +/- 52 to 1139 +/- 75 beats/min (mean +/- S.E., P less than 0.01). This ciliostimulatory effect was dose-dependent, with the maximal increase and EC50 value being 17.4 +/- 1.0% (P less than 0.05) and 6.10(-11) M, respectively. The VIP-induced increase in CBF was abolished by pretreatment of cells with [4-Cl-D-Phe6, Leu17]-VIP, a VIP receptor antagonist. The neutral endopeptidase inhibitor phosphoramidon (10(-5) M) potentiated the effect of VIP, so that the CBF dose-response curve for VIP was shifted to lower concentrations by 0.5 log U. The administration of VIP increased cyclic AMP levels in epithelial cells, an effect that was also potentiated by phosphoramidon. These results suggest that VIP may interact with its specific receptors and stimulate airway ciliary activity probably through the activation of adenylate cyclase, and that neutral endopeptidase may play a role in modulating this effect of VIP.

Animals↗

PubMedDate not supplied

Mucosal dysfunction and damage induced by platelet activating factor (PAF).

The effect of PAF on human nasal mucosa was investigated in vitro. Normal paranasal sinus mucosa was obtained from the ethmoid sinuses by surgical procedure and incubated in the form of tissue culture. Ciliary movement was viewed under an inverted microscope and recorded on video tapes, and its activity was measured photoelectrically. Morphological alterations were examined by light and electron microscopy. PAF inhibited ciliary activity of human nasal mucosa, in a time and a dose dependent manner, at concentrations from 10(-6)M to 10(-10)M, while no significant change was observed at 10(-11) M. Lyso-PAF exhibited minimal effect on the mucosa at a concentration of 10(-6) M. Morphological alterations of the epithelial layer of the mucosa such as edema, cell exfoliation and desquamation were found to increase across time. Ultrastructural alterations were observed prior to inhibition of ciliary activity. These data indicate the cytotoxic effect of PAF on human paranasal sinus mucosa.

Cell Membrane↗

PubMed1987

Acute effects of isopropyl alcohol exposure on the middle ear mucosa.

Guinea pigs were exposed to 400 ppm or 5500 ppm of isopropyl alcohol (IPA) for 24 successive hours, and then middle ear mucosal samples in both proximal and distal sites to the eustachian tube were obtained for functional and morphological examinations. The ciliary activity was examined according to the photoelectric method of Ohashi and Nakai. The morphology of the middle ear lining was examined by transmission electron microscopy. The results showed that IPA at the allowable level of 400 ppm has an acute effect on the mucociliary system of the middle ear mucosa. Recovery from damage occurs within two weeks. At higher levels of exposure to IPA (more than 10 times the allowable level) moderate deterioration of the ciliary activity and severe damage of epithelial cells were observed and recovery within two weeks was not seen. It is concluded that IPA at the allowable level of 400 ppm does not cause significant middle ear disorders, but workers exposed to higher levels of IPA should be given careful otolaryngological examinations and follow-up observations.

1-Propanol↗

PubMed1975

Modification of intensity and direction of electron flow across bileaflet membranes.

The intensity and the direction of electron flow across chloroplast extract bilayer membranes are modified by the presence of biliproteins. Biliproteins including C-phycocyanin, phycoerythrin, allophycocyanin, and Chroomonas phycocyanin enhance the photosensitivity of the membranes. The photoelectric spectra of the membranes in the presence of biliproteins correlate with the absorption spectra of these biliproteins. Experiments are presented to demonstrate the specific character of the electron-directing ability of biliproteins. A possible mechanism involving the interaction between the biliproteins and the membranes is proposed.

Cell-Free System↗

PubMed1981

Transmembranous incorporation of photoelectrically active bacteriorhodopsin in planar lipid bilayers.

Various methods to incorporate bacteriorhodopsin in black lipid membranes are reported. Both purple membrane patches and monomeric bacteriorhodopsin were used as starting material. The incorporation of bacteriorhodopsin into planar lipid bilayers was achieved by the following methods. (i) Purple membrane patches were transferred from water to solutions of lipids in n-alkanes. Black membranes were formed from such organic suspensions. (ii) Lipid layers containing solvent and purple membranes were spread on an air/water interface. These layers were used to form planar bilayers. (iii) Vesicles containing purple membranes or monomeric bacteriorhodopsin were spread on an air/water interface and, from the resulting layer, bilayers were formed. On illumination, steady-state photocurrents were observed in all three cases, indicating that these methods lead to functional transmembranous integration of the protein in the planar black lipid membrane. The influence of an applied electric field on the pumping process was studied on membranes formed by using method i. At approximately 200 mV, the photocurrent tends to zero. Furthermore, it was possible to make planar lipid bilayers photoelectrically active by adding vesicles containing monomeric bacteriorhodopsin to the bathing solution. Because, in this case, only transient photocurrents were observed, it can be concluded that the vesicles are attached to but not fused with the black lipid membrane.

Bacteriorhodopsins↗

PubMed1989

Synchronization between beating cilia.

A novel quantitative parameter is proposed to define and measure the degree of synchronization between two small ciliary areas. These areas can be close to or far from one another. The Pearson correlation factor is used to define the degree of synchronization by a single number. This approach is based on a computerized, dual photoelectric method which simulataneously measures the scattered light from two small areas on the ciliary epithelium or its tissue culture. The measurements were performed on tissue culture from frog's palate epithelium. It was found that: (a) the degree of synchronization decreases, as a function of distance; (b) the correlation is fairly high even at relatively large separations, when measured on the same patch; (c) on a given patch the synchronization factor is independent of the direction of the metachronal wave; (d) close disconnected ciliary cells exhibit fairly high correlation; (e) disconnected randomly choosen ciliary cells at relatively large separation distances exhibit relatively low correlation, smaller by a factor of 2 than the correlation factor at the same distances when measured along the metachronal wave; (f) the average frequencies' ratio and the metachronal wavelength can be used as first-order indicators of ciliary synchronization; (g) there is a spread of metachronal wavelengths even over a single well-organized patch.

Animals↗

PubMed1978

[Research on the artificial regulation of sex in animals in the USSR].

The problem of artificial sex control was cardinally solved only for the silkworm among the domestic animals. The artificial sex control is realized by means of several methods. The artificial ameiotic parthenogenesis allows to obtain isogenic parthenogenetic progeny of only female sex. The meiotic parthenogenesis, on the contrary, gives only male progeny characterized by homozygosis by all genes. As a result of androgenesis with the participation of ooplasm and male nuclear material, only male progeny develops as well. Sex marked strains in which the female and male eggs are coloured in different may were obtained by means of translocation of the dominant genes controlling the egg colour on W chromosome determining the female sex. This allows readily to pick out the eggs of desirable sex only with the help of photoelectric equipment. The males of a specially raised strain balanced by two non-allelic sex-linked lethals, when being crossed with the females of any other strain, give male progeny only. The developed methods of sex control have found wide application in theoretical investigations of various directions and practical sericulture.

Animals↗

PubMed1985

The genotoxicity of selenium.

Selenium at nutritional levels has been shown to have numerous anticarcinogenic or preventative effects against carcinogen-induced breast, colon, liver and skin cancer in animals. Many of these anticarcinogenic effects have been summarized. In addition, numerous mutagenic and antimutagenic effects of selenium compounds have been reported. Some of the selenium compounds frequently tested for mutagenicity are listed in Table 1. Because of the numerous reported anticarcinogenic and preventative effects of selenium, many individuals are supplementing their diets with amounts of selenium that are greater than the recommended daily requirement. Selenium is also used widely in industrial products such as selenium rectifiers, photoelectric batteries, alloys and paints. Because selenium at higher levels is known to be toxic, there should be a greater understanding about its genotoxic as well as its beneficial effect. The object of this review is to summarize experimental evidence both for the antimutagenic and the mutagenic effect of selenium.

Alkylation↗

PubMed2004

Inhibitory effect of buflomedil on prostate alpha1A adrenoceptor in the Wistar rat.

The inhibitory effect of buflomedil on alpha1A-adrenoceptor (AR) in the prostate of Wistar rat was investigated in this study. Normotensive and spontaneous hypertensive rats were orally fed with buflomedil (150 mg/kg). The drug effects on blood pressure and heart rate were monitored by photoelectric volume oscillometric method. Prostate tissue strips from normotensive rats were contracted in vitro in organ bath by phenylephrine (10(-8) to 10(-2)M). The inhibitory effects of buflomedil (10(-9) to 10(-7)M) on the phenylephrine-induced contractions were measured. Radioligand binding displacement study by buflomedil was performed on rat prostate alpha1A-adrenoceptor (AR) and spleen alpha1B-AR. Furthermore the effects of buflomedil and WB-4101 on phenylephrine (10 microM) activated uptake of 2-[14C]-deoxy-d-glucose (2-DG) into C2C12 cells were evaluated. The results showed that buflomedil feeding did not alter the systolic blood pressure of either spontaneous hypertensive rats or normal rats. Dose-inhibition curves of phenylephrine-induced prostate contraction demonstrated a higher potency of buflomedil than tamsulosin. Buflomedil displaced [3H]prazosin binding in a concentration-dependent manner both in rat prostate alpha1A-AR and spleen alpha1B-AR. The ratio of affinity to alpha1A-AR and alpha1B-AR for buflomedil was 4.06/6.84, indicating selectivity on alpha1A-AR over alpha1B-AR. Activation of C2C12 cell alpha1A-AR by phenylephrine increased the glucose uptake to 116%. Both buflomedil and WB-4101 inhibited the uptake in a concentration-dependent manner. In conclusion, the findings showed that buflomedil has preferential alpha1A-AR antagonistic effect to inhibit prostate contraction without significantly affecting the blood pressure.

Adrenergic alpha-Agonists↗

PubMed1987

Control of a teleost social signal. I. Neural basis for differential expression of a color pattern.

Territorial male Haplochromis burtoni (Teleostei; Cichlidae) have a dark facial stripe, the 'eyebar', which can appear and disappear within seconds, independently of other coloration patterns. It is used to signal territory ownership and aggressive intent. Some males, called 'barless', have functional melanophores in the eyebar region but never display this pattern, because melanin in eyebar pigment cells is never dispersed. The eyebar melanophores are controlled by a specialized branch of the maxillary nerve. Lesioning the 'eyebar nerve' resulted in immediate melanin dispersion and consequent darkening of the eyebar pattern, and it abolished the normal paling response in all behavioral situations. Nerve lesion produced similar results in both barred and barless males, except that the coloration of the denervated eyebar in barless males was more similar to camouflage markings than to the conspicuous black eyebar used as a social signal. Electrical stimulation of the maxillary nerve produced melanin aggregation. Photoelectric recordings of this paling response revealed no differences between barred and barless males, or between the eyebar and other facial chromatophores that do not function as visual displays. Thus, the difference in the physiological state of eyebar melanophores in intact barred and barless males cannot be explained by differences in peripheral nerve anatomy or physiology.

Aggression↗

PubMed2005

Genetic cloning and functional expression in Escherichia coli of an archaerhodopsin gene from Halorubrum xinjiangense.

Pairs of PCR primers that targeted the archae/bacteriorhodopsin gene were used to clone the archaerhodopsin (aR) gene of Halorubrum xinjiangense strain BD-1(T), and this gene was sequenced and functionally expressed in Escherichia coli. Recombinant E. coli cells harboring the plasmid carrying this gene became slightly purple or blue depending on whether they were supplemented with all- trans retinal or 3,4-dihydroretinal, respectively, during induction with IPTG. The purple and blue membranes from the recombinant E. coli showed maximal absorption at 555 and 588 nm, respectively, which are different from maximal absorption at 568 nm of the wild-type purple membrane. Purple membranes from the recombinant E. coli and from strain BD-1(T) were investigated in parallel. The E. coli purple membrane was fabricated into films and photoelectric responses were observed that depended on the light-on and light-off stimuli.

Amino Acid Sequence↗

PubMed1984

Ciliary beat frequency of human middle-ear mucosa measured in vitro.

Brush biopsies from the middle-ear (ME) and nasal mucosa were taken from a 4-year-old girl with complete situs inversus, recurrent otitis media and tonsillitis, who underwent tonsillectomy, adenoidectomy and bilateral myringotomy with insertion of ventilation tubes. Ciliary beat frequencies (CBF, Hz.) of the ME and nasal samples, measured by a photoelectric system equipped with a fiber-optic probe, were 9.5 Hz. (+/- 1.2) and 13.7 Hz. (+/- 4.1) respectively. These values are similar to CBF of nasal samples obtained from normal subjects. In vitro CBF assessment is a useful investigative tool for the study of mucociliary activity in the ME, as in patients suspected to have ciliary dyskinesia syndrome.

Cell Movement↗

PubMed1987

Characterization of metachronal wave of beating cilia on frog's palate epithelium in tissue culture.

1. A method is suggested to measure phase versus distance between beating cilia by means of a photoelectric device. A statistical method interpreting the results thus obtained is discussed. 2. It was found that: (a) an average phase exists between beating cilia, (b) despite strong fluctuations in phase on a short time scale, the average phase was kept constant over periods of 8 h, (c) the ciliary frequency and the length of the metachronal wave can be measured simultaneously. 3. The average phase differences are linearly dependent on distance. 4. The effective range of synchronization between cilia is of the order of 10 micron indicating that it occurs within one cell. 5. During the cycle of ciliary beating there are periods where coupling is stronger.

Animals↗