Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “sensitization”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1992

Doxorubicin sensitivity pattern in a panel of small-cell lung-cancer cell lines: correlation to etoposide and vincristine sensitivity and inverse correlation to carmustine sensitivity.

The aim of our investigations is to evaluate whether the sensitivity patterns of small-cell lung-cancer (SCLC) cell lines in vitro can be used in evaluating new drugs and in selecting drugs for the optimization of combination therapy. In our attempts to obtain a panel of cell lines demonstrating differential patterns in sensitivity, we have developed three SCLC lines exhibiting different types of multidrug resistance (MDR). In the present investigations we compared the sensitivity patterns shown by five wild-type SCLC lines and three MDR lines in response to six different types of drugs: doxorubicin, cytarabine, carmustine, cisplatin, vincristine, and etoposide. In the wild-type SCLC cell lines, the range of variation in sensitivity to all drugs was within a factor of 10. Cell lines showing low sensitivity to doxorubicin also exhibited low sensitivity to etoposide and vincristine, and vice versa. In contrast, the pattern of sensitivity to carmustine was almost the opposite of that to doxorubicin. A tendency to an inverse relationship between doxorubicin and carmustine sensitivity was also observed when doxorubicin sensitivity was reduced in near stationary cells and in cells exposed to the metabolic inhibitor 2-deoxy-D-glucose. In agreement with the pattern observed for the wild-type lines, all of the MDR sublines demonstrated collateral sensitivity to carmustine. As to cytarabine, the wild-type lines expressed a sensitivity pattern similar to that shown in response to doxorubicin. Interestingly, the opposite pattern was found in the MDR lines, as all three demonstrated cytarabine hypersensitivity. The combination of alkylating agents and "MDR" drugs are of proven clinical benefit in the treatment of solid tumors, as is the combination of anthracycline and cytarabine in acute myeloid leukemia. The experimentally derived sensitivity data on cytarabine, alkylating agents, and MDR drugs (i.e., etoposide, doxorubicin, vincristine) thus resemble the clinical experience with these drugs, and we conclude that the use of a clonogenic assay on the described panel of SCLC cell lines can give valuable information for the selection of agents for combination therapy.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1989

Characterization of versilin-sensitive sites in self-sensitive producer and sensitive non-producer or unrelated organism.

Studies on self-sensitivity of producer mutant vs. sensitivity of non-producer parent and unrelated organism showed that versilin inhibited spore germination and sporulation in the self-sensitive producer mutant, non-producer parent Aspergillus versicolor N5 and the unrelated sensitive Trichophyton rubrum. Sporulation appeared to be more sensitive than spore germination. The inhibition of in vivo synthesis of protein was very marked, but inhibition of RNA and DNA was slight and moderate, respectively. Thus versilin was not specific in its action, but the principal sensitive site was protein synthesis, as further suggested by inhibition of polyU-directed in vitro synthesis of polyphenylalanine. The activation of leucine was unaffected, but the formation of leucyl-tRNA was severely inhibited in all three strains. The differences in sensitivities between the strains were the same, whether as whole cells or as cell-free extracts. Thus the nature of the sensitive site appeared to be identical in the self-sensitive producer and sensitive non-producer or unrelated organism.

Anti-Bacterial Agents↗
PubMed1992

Genetic covariation in low alcohol-sensitive and high alcohol-sensitive selected lines of rats: behavioral and electrophysiological sensitivities to the depressant effects of ethanol and the development of acute neuronal tolerance to ethanol in situ at generation eight.

Phenotypic differences in behavioral and initial neuronal sensitivities to acute ethanol (EtOH) administration were examined and compared among replicate lines of rats, which were selectively bred for low and high EtOH sensitivity. The eighth generation of HAS (EtOH-sensitive) and LAS (EtOH-insensitive) rats were significantly different in terms of sensitivity both to EtOH-induced loss of righting response (sleep time) and to EtOH-induced depressions of cerebellar Purkinje neuron firing rates. This study provides the first evidence for a significant correlation between behavioral and electrophysiological EtOH sensitivities among individual animals and between replicate selected rodent lines. These data support the hypothesis that a genetic correlation exists between these two phenotypes. In addition, the LAS rats expressed a significantly higher incidence of acute cellular tolerance to the depressant neuronal effects of repeated local applications of EtOH over a period of a few minutes. We have characterized this response and concluded that it may contribute to EtOH sensitivity. However, our data also suggest that the EtOH insensitivity of cerebellar Purkinje neurons in LAS rats is not only a consequence of acute neuronal tolerance to EtOH, but also due to low initial EtOH sensitivity of these neurons. Both behavioral and electrophysiological EtOH phenotypes of LAS and HAS rats have diverged with the application of selection pressure for behavioral EtOH sensitivity; these data suggest that the mechanisms underlying neuronal sensitivity and acute neuronal tolerance to EtOH are important in determining the behavioral EtOH sensitivities of these animals.

Action Potentials↗
PubMed1986

The inactivation of [Met5]-enkephalin by bestatin-sensitive aminopeptidase, captopril-sensitive peptidyl dipeptidase A and thiorphan-sensitive endopeptidase-24.11 in mouse vas deferens.

The enkephalin-hydrolyzing peptidases in mouse vas deferens were studied and compared with those in guinea pig ileum which had been characterized in the previous study. The present results showed that three distinct peptidases, bestatin-sensitive aminopeptidase, captopril-sensitive peptidyl dipeptidase A, and thiorphan-sensitive endopeptidase-24.11, played a critical role in the inactivation of enkephalin in mouse vas deferens, being consistent with the previous results obtained with guinea pig ileum. However, the data in both previous and present studies showed that the activity of the bestatin-sensitive aminopeptidase relative to that of either the captopril-sensitive peptidyl dipeptidase A or the thiorphan-sensitive endopeptidase-24.11 in guinea pig ileum was higher than that in mouse vas deferens, while the activity of either peptidyl dipeptidase A or endopeptidase-24.11 relative to that of aminopeptidase in mouse vas deferens was higher than that in guinea-pig ileum. In contrast to these three enzymes, both L-tyrosyl-L-tyrosine-sensitive dipeptidyl aminopeptidase and D-phenylalanine-sensitive carboxypeptidase were suggested not to be involved significantly in the inactivation of enkephalin in mouse vas deferens as well as guinea pig ileum.

Amino Acids, Sulfur↗
PubMed1987

Chromosomal instability in mutagen-sensitive mutants isolated from mouse lymphoma L5178Y cells. II. Abnormal induction of sister-chromatid exchanges and chromosomal aberrations by mutagens in an ionizing radiation-sensitive mutant (M10) and an alkylating agent-sensitive mutant (MS1).

To determine the mutual relationships between cell survival and induction of sister-chromatid exchanges (SCEs) as well as chromosomal aberrations (CAs), mutagen-induced SCEs and CAs were analyzed in an ionizing radiation-sensitive mutant (M10) and an alkylating agent-sensitive mutant (MS 1) isolated from mouse lymphoma L5178Y cells. The levels of CA induction in both mutants strictly corresponded to the sensitivity to lethal effects of mutagens, except that caffeine-induced CAs in M10 are considerably lower than those in L5178Y. The results clearly indicate that except for caffeine-induced CAs in M10, mutagen-induced lethal lesions are responsible for CA induction. In contrast, SCE induction in mutants was complicated. In M10, hypersensitive to killing by gamma-rays, methyl methanesulfonate (MMS), and 4-nitroquinoline 1-oxide (4NQO), but not sensitive to UV or caffeine, the frequency of SCEs induced by gamma-rays was barely higher than that in L5178Y, and the frequencies of MMS- and UV-induced SCEs were similar to those in L5178Y, but 4NQO- and caffeine-induced SCEs were markedly lower than those in L5178Y. MS 1, which is hypersensitive to MMS and caffeine, but not sensitive to UV or 4NQO, responded to caffeine with an enhanced frequency of SCEs and had a normal frequency of MMS-induced SCEs, but a reduced frequency of UV- and 4NQO-induced SCEs. Thus, susceptibility to SCE induction by mutagens is not necessarily correlated with sensitivity of mutants to cell killing and/or CA induction by mutagens. Furthermore, the spontaneous levels of SCEs are lower in M10 and higher in MS 1 than that in L5178Y (Tsuji et al., 1987). Based on these results, we speculate that M10 may be partially defective in the processes for the formation of SCEs caused by mutagens. On the other hand, MS 1 may modify SCE formation-related lesions induced by UV and 4NQO to some repair intermediates that do not cause SCE formation. In addition, MMS-induced lethal lesions in MS 1 may not be responsible for SCE induction whereas caffeine-induced lethal lesions are closely correlated with SCE induction. Thus, the lesions or mechanisms involved in SCE production are in part different from those responsible for cell lethality or CA production.

4-Nitroquinoline-1-oxide↗
PubMed1986

125I-fibrin deposition in contact sensitivity reactions in the mouse. Sensitivity of the assay for quantitating reactions after active or passive sensitization.

We investigated the clotting associated with delayed hypersensitivity (DH) responses in the mouse by sensitizing the animals to the contactant oxazolone (Ox), and then administering 125I-guinea pig fibrinogen i.v. 10 to 30 min before antigen challenge 5 days later. Early (4 to 8 hr) contact sensitivity (CS) responses in immunized mice were barely detectable by three conventional measures of CS, but the total 125I-cpm in ears challenged with hapten was 3.6 to 4.5 X that in control ears challenged with vehicle alone; moreover, the amount of urea-insoluble cpm (cross-linked 125I-fibrin-associated cpm) in the reactions to Ox was 6.5-fold to 8.2-fold that present in the control reactions. In 24 hr reactions that were near peak intensity by measurements of ear swelling, ear weight ratios, and ratios of 125I-5-iodo-2-deoxyuridine-labeled leukocyte infiltration, the cpm in antigen-challenged ears exceeded that in control ears by 13-fold to 53-fold. In addition, antigen-challenged ears contained 27 to 300 X the urea-insoluble cpm present in control ears. 125I-Fibrin deposition was not a specific characteristic of CS reactions, because a small amount of urea-insoluble reactivity was also detected in some reactions to Ox in native mice. Nevertheless, the assay was exquisitely sensitive and readily detected quantitative differences between the immunologically specific and nonspecific reactions at very early intervals after challenge or with suboptimal doses of antigen. Furthermore, it was more sensitive than conventional tests of CS in detecting the reactions elicited in mice that had been passively sensitized to Ox by adoptive transfer of immune lymph node cells. Finally, we showed that the assay gave similar results when we tested CS reactions elicited in mast cell deficient WBB6F1-W/Wv and littermate normal (+/+) mice, demonstrating yet another similarity in the phenotype of DH reactions elicited in the presence or absence of mast cells.

Animals↗
PubMed1988

Cross-tolerance and cross-sensitization between morphine analgesia and naloxone-sensitive and cimetidine-sensitive stress-induced analgesia.

Recent studies have shown that different regimens of footshock elicit either "opiate" (naloxone-sensitive) or "histaminergic" (cimetidine-sensitive but naloxone-insensitive) analgesic responses. Presently, the nature of these responses was further investigated by characterizing the development of tolerance to these stress paradigms and by assessing the degree of cross-tolerance between these treatments and morphine (MOR) in rats. Daily exposure to the "opiate" stress paradigm for 7 days resulted in a significant loss of this form of footshock-induced analgesia (FSIA), but the same exposure to the "histaminergic" regimen resulted in no such tolerance. One day later, animals from the "opiate"-stressed group exhibited MOR analgesia that was comparable to that in unstressed animals, whereas animals chronically exposed to the "histaminergic" paradigm showed highly potentiated responses to MOR. However, when naive animals were made tolerant to MOR, acute "opiate" FSIA was significantly attenuated, whereas the "histaminergic" analgesia was unaffected. These results, showing one-way cross-tolerance between MOR and "opiate" FSIA, are consistent with the hypothesis that opiate FSIA uses a subset of opiate receptors activated by systemic MOR. The one-way cross-sensitization between MOR and "histaminergic" analgesia observed presently, taken with previous findings, suggests that opiate-containing and histamine-containing neurons comprise separate endogenous analgesic systems that mutually inhibit each other. The absence of tolerance and opiate cross-tolerance exhibited by the cimetidine-sensitive analgesia suggests that drugs designed to activate this analgesic system should be devoid of such liabilities.

Analgesia↗
PubMed1979

Predictive value of the analogy between hormone-sensitive adenylate cyclase and light-sensitive photoreceptor cyclic GMP phosphodiesterase: a specific role for a light-sensitive GTPase as a component in the activation sequence.

We report experiments which involve a light sensitive GTPase in the light dependent activation of retinal rod 3'5'-cyclic guanosine monophosphate (cGMP) phosphodiesterase (PDE). The data suggest that the light activated GTPase is intermediate between rhodopsin and PDE in the light-dependent activation sequence. We list the many striking similarities between hormone sensitive adenylate cyclase and light activated PDE in order to emphasize that the findings presented herein may have predictive value for ongoing studies of the hormone sensitive adenylate cyclase specifically regarding the role of the hormone activated GTPase in the activation sequence.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1976

Milk sensitivity and soybean sensitivity in the production of eczematous manifestations in breast-fed infants with particular reference to intrauterine sensitization.

Three cases of milk sensitivity and two of soybean sensitivity are presented, suggesting that both pre-natal and post-natal sensitization may have been involved in the production of eczematous manifestations of early infancy. Hemagglutinating antibody titers against lactalbumin and soybean in the amniotic fluid were unusually high. This suggests that hemagglutinating antibody estimation against foods in the amniotic fluid may possibly predict infantile allegic manifestations in the newborn.

Adult↗
PubMed1979

Comparative studies of wild-type and cold-mutant (temperature-sensitive) influenza viruses: independent segregation of temperature-sensitivity of virus replication from temperature-sensitivity of virion transcriptase activity during recombination of mutant A/Ann Arbor/6/60 with wild-type H3N2 strains.

RNA 1 (see end of Summary) of a cold-adapted and temperature-sensitive (ts) influenza virus mutant A/Ann Arbor/6/60 has a different mobility from RNA 1 of wild-type (wt) A/Ann Arbor/6/60 when subjected to electrophoresis through acrylamide/agarose gels in the absence of denaturing agents. Detection of this lesion in RNA 1 of the mutant virus was dependent on the temperature of the gel during electrophoresis. Because RNA 1 is believed to code for a protein involved in virus-specific RNA synthesis we compared phenotypes of virion transcriptases in the wt and mutant viruses. The enzyme of the mutant virus was found to be about 40% less active at 40 degrees C than the enzyme of the wt virus when related to their activities at 31 degrees C. Two cold-adapted ts recombinants which derive their RNA 1 from the mutant A/Ann Arbor/6/60 have virion transcriptases with a phenotype similar to that of their mutant parent. Three different cold-adapted ts recombinants, however, which also derive their RNA 1 from the mutant A/Ann Arbor/6/60, have virion transcriptases with a phenotype similar to that of wt virus. We conclude, therefore, that the conditional-lethal ts property of A/Ann Arbor/6/60 mutant and its recombinants is independent of the phenotypic marker observed for the A/Ann Arbor/6/60 mutant virion transcriptase, and that the lesion in RNA 1 of the mutant may also be unrelated to the observed difference between virion transcriptases of the mutant and wt A/Ann Arbor/6/60 viruses. The phenotypes of the virion transcriptases in recombinants did, however, correlate with the derivation of their RNA 2. This suggests that the increased temperature-sensitivity of virion transcriptase of the A/Ann Arbor/6/60 mutant is caused by either (1) a lesion (not necessarily conditionally lethal) that occurred in its RNA 2 during the course of cold-adaptation, or (2) a lesion in another gene whose product is a component of the virion transcriptase complex, but which lesion is only expressed phenotypically when there is a synergistic interaction in the transcriptase complex with the product of A/Ann Arbor/6/60 rna 2.

Cold Temperature↗
PubMed1990

A review of the Buehler guinea pig skin sensitization test and its use in a risk assessment process for human skin sensitization.

The Buehler test is a valuable procedure for screening the sensitization potential of chemicals prior to human exposure. Our experience of over 20 years has shown it to be effective in detecting strong, moderate, and most weak sensitizers. The topical exposure inherent in the Buehler test allows it to be utilized to investigate dose responses, cross reactivity between structurally related chemicals, and the sensitization potential of contaminants in raw material mixtures. For safety assessment purposes, Buehler test results provide an initial indication of the sensitization potential of the material in question under relevant, but exaggerated, exposure conditions. These results can be compared to results on benchmark chemicals to assess sensitization risk for subsequent human exposure. Optimizing the sensitivity of the Buehler test requires adherence to the published methodology and proper interpretation of the challenge and rechallenge data obtained. Adjuvant-type test methods are generally considered to be more sensitive than topical methods. However, when done properly, topical test procedures such as the Buehler test or the open epicutaneous test can accurately detect most chemicals with any realistic potential for sensitizing humans by the topical route. Moreover, from a risk assessment perspective, these topical tests avoid the problems of overestimating the weak sensitization potential of many topically applied materials or underestimating the sensitization potential of very strong sensitizers; both are potential concerns with invasive adjuvant-type test methods. The Buehler test or other topical test methods are particularly valuable for comparative sensitization risk assessment since human sensitization data on benchmark materials are all derived from topical exposure. The risk assessment is developed by comparing the guinea pig data on the new material versus relevant benchmark chemicals or formulations and also by evaluating the existing human sensitization data on the benchmark material. These data are then utilized to predict human sensitization risk from topical exposure to the new material. Confirmation of human safety can be derived from human repeat insult patch testing (HRIPT) and other clinical tests such as the product use test and the diagnostic patch test. Utilized in this manner, the Buehler test is an integral component of an overall skin sensitization safety assessment program for a new chemical or product formulation.

Animals↗
PubMed1978

Food sensitivity reported by patients with asthma and hay fever. A relationship between food sensitivity and birch pollen-allergy and between food sensitivity and acetylsalicylic acid intolerance.

Among adult patients with bronchial asthma and/or allergic rhinitis undergoing allergological investigation with skin test, nasal provocation test and RAST, 1129 answered a questionaire regarding food sensitivity (FS). 276 (24%) of the patients reported some kind of allergic symptoms on eating or handling various foods, of which hazel nut, apple and shell fish were the most often named. Females reported FS more often than males. A correlation was found between birch pollen allergy and FS with nuts, apple, peach, cherry, pear, plum, carrot and new potato. The higher the degree of birch pollen allergy, according to skin test, RAST or provocation test, the higher the frequency of FS. A correlation was found too between acetylsalicylic acid intolerance and FS with some foods, e.g. nuts, strawberry, almond, green pepper, hip, chocolate, egg, cabbage, milk and wine. The connection between birch pollen allergy and FS is probably explained by the structural relationship between birch pollen allergen and some allergens of the foodstuffs, whereas the high incidence of FS in acetylsalicylic acid-intolerant patients is probably explained by additives in foods as well as salicylates or benzoates naturally occurring in some food.

Adolescent↗
PubMed1991

Gamma-ray- and UV-sensitive strains of a radioresistant cell line: isolation and cross-sensitivity to other agents.

Two gamma-ray-sensitive and two ultraviolet (UV)-sensitive variants were isolated from the gamma-ray- and UV-resistant TN-368 lepidopteran insect cell line. The isolation was performed by inducing mutations in the TN-368 cells using ethyl methanesulfonate, growing them for an expression period, irradiating with 137Cs gamma rays or 254-nm UV radiation, allowing cells to incorporate 5-bromodeoxyuridine (BrdU) in the presence of hydroxyurea (DNA repair synthesis), and finally irradiating with 365-nm UV radiation to cause DNA strand breakage at sites of BrdU incorporation with the intent of killing those cells that have undergone DNA repair synthesis and sparing those cells which, for a variety of reasons, did not. The survival of the Cs2 and Cs7 variants exposed to X rays is significantly different from the parent TN-368 line at the P less than 0.0001 level. The survival of the UV10 and UV19 variants exposed to UV radiation is different from the parent at the P less than 0.0001 and P less than 0.003 levels, respectively. In cross-sensitivity testing of the gamma-ray-sensitive variants, only Cs2 is more sensitive to 254-nm UV and only Cs7 is more sensitive to 44 degrees C heating; both are sensitive to PUVA. The UV-sensitive mutants are both sensitive to X irradiation, PUVA, and mitomycin C. However, UV10 is not sensitive to 44 degrees C heating while UV19 is, making UV19 the only variant strain sensitive to all agents examined. Despite the isolation procedure which was intended to select for DNA repair-deficient cells, the results suggest that a more general mechanism is responsible for the sensitivity of the variant cells to the agents tested.

Animals↗
PubMed1989

Contact sensitivity to topical antimicrobials. (II). Sensitizing potentials of some topical antimicrobials.

A predictive study comparing the sensitizing potentials of some topical antimicrobials, using a modified Beuhler's technique, showed that over-the-counter (OTC) antimicrobials were more sensitizing than prescribed topical antibiotics. Among OTC antimicrobials, proflavine was the most potent sensitizer (4/10 guinea pigs); parachlorometaxylenol, benzalkonium chloride and propamidine isethionate moderate sensitizers (2/10 guinea pigs); iodine a weak sensitizer (1/10 guinea pigs); and chlorhexidine and cetrimide very weak sensitizers (0/10 guinea pigs). Among prescribed topical antibiotics, neomycin was a moderate sensitizer (2/10 guinea pigs); gentamycin and chloramphenicol weak sensitizers (1/10 guinea pigs); kanamycin, clioquinol, polymyxin B, bacitracin, tetracycline, sodium fusidate and fusidic acid very weak sensitizers (0/10 guinea pigs). There was good correlation between sensitizing potentials in animal studies and clinical experience of contact allergy to these topical antimicrobials.

Administration, Topical↗
PubMed1987

Regional variation of contrast sensitivity across the retina of the achromat: sensitivity of human rod vision.

1. Detection thresholds for two-dimensional Gabor functions of varying spatial and temporal frequency were used to investigate the post-receptoral sensitivity across the retina of the typical and complete achromat. 2. Under photopic conditions there is no evidence for post-receptoral cone function at any retinal eccentricity investigated. Sensitivity saturates in a way consistent with known psychophysical and electrophysiological measures of rod saturation. This occurs in a unitary fashion across the retina. 3. Under scotopic conditions the regional fall-off in spatio-temporal sensitivity is similar for the achromat and duplex retina. This suggests that the rods in the achromat make normal neural connections. 4. Taken together this supports the contention that the typical and complete achromat is a functional rod monochromat and hence can be used to explore the sensitivity of the isolated rod post-receptoral mechanism under mesopic conditions where its sensitivity is optimal. This is where its contribution is most difficult to isolate in the duplex retina. 5. For the human rod mechanism, mesopic post-receptoral sensitivity for all spatio-temporal stimuli is optimal in the central region of the retina and falls off as a function of eccentricity. 6. For localized stimuli, peripheral spatial sensitivity is reduced evenly at all spatial frequencies compared with that of the central retina. A similar displacement of the spatial sensitivity function of the rod mechanism occurs as illuminance is reduced. 7. For localized stimuli, temporal acuity of the rod mechanism is around 20-25 Hz irrespective of retinal position. As the illuminance is further lowered dynamics of the rod pathway are reduced irrespective of retinal position and the sensitivity function maintains a bandpass shape. 8. The regional distribution sensitivity of the rod mechanism changes as illuminance is reduced from mesopic to scotopic levels.

Color Vision Defects↗
PubMed1990

Azimuthal sensitivity of neurons in primary auditory cortex of cats. I. Types of sensitivity and the effects of variations in stimulus parameters.

1. Preliminary to studying the organization of azimuthal sensitivity of neurons along frequency-band strips in the primary auditory cortex (AI) of cat (see companion paper), this study examined the sensitivity of 251 units in cat AI to variations in the azimuthal location of sound sources in the frontal hemifield. Most units (231) were tested with tones at the characteristic frequency (CF; frequency to which the unit had the lowest threshold). Unit CFs ranged from 5 to 36 kHz. A large number of units (91) were tested with broadband noise stimuli, and a few units were also tested at other frequencies within the cell's tuning response area. 2. When tested at stimulus intensities 20-30 dB above CF or noise threshold, the different forms of azimuthal sensitivity exhibited by AI neurons could be divided into (1) contra-field azimuth functions; (2) ipsi-field functions; (3) central-field functions; (4) omnidirectional functions, and (5) multipeaked functions. Contra-field azimuth functions were the most prevalent, with 45.9% of units tested with CF tones and 42.9% of units tested with noise exhibiting this type of azimuthal sensitivity. Ipsi-field azimuthal sensitivity was found in 16.9% of units tested with CF tones and 19.8% of units tested with noise. Central-field azimuthal sensitivity was seen in 10.8% of units tested with CF tones and 17.6% of units tested with noise. Omnidirectional azimuthal sensitivity was seen in 19.9% of units tested with CF tones and 17.6% of units tested with noise, whereas multipeaked azimuthal sensitivity was found in 6.5% of units tested with CF tones and 5.5% of units tested with noise. 3. The effects of increasing stimulus intensity on azimuthal sensitivity were examined in 185 units tested with CF tones and 67 units tested with noise. For four major classes of azimuthal sensitivity (contra-field, ipsi-field, central-field and omnidirectional), the most common effect (approximately 60% of each class) was for the azimuth function to remain constant in form by the defining criteria for these classes. The next most common effect for all classes except omnidirectional azimuth functions was for an expansion of the azimuthal range eliciting responses. (The definition of omnidirectionality precluded any expansion of the response range in this class of azimuth function). A smaller number of units in some classes showed a compression of the azimuth function to a smaller response range, and others showed more complex expansive and compressive effects with increasing stimulus intensity.(ABSTRACT TRUNCATED AT 400 WORDS)

Acoustic Stimulation↗
PubMed1987

Solubilization and separation of ethacrynic acid (EA) highly sensitive and EA less sensitive Mg2+-ATPases in the rat brain.

Rat brain microsomal Mg2+-ATPases with two distinct activities: ethacrynic acid (EA) highly sensitive and EA less sensitive Mg2+-ATPase activities were solubilized by the combined treatment with 10 mM 3-(3-chlolamidopropyl)-dimethylammonio-1-propane-sulfate (CHAPS) and 30 mM octyl-beta-D-glucoside. The solubilized enzymes had properties similar to those of the membrane-bound enzyme in microsomes with respect to the sensitivity to EA and Cl-, although the optimal pH and the affinity to ATP were slightly altered after the solubilization. Fast protein liquid chromatography of the solubilized enzymes on an anion-exchanger (Mono Q) column with a linear NaCl gradient (0-1.0 M) yielded separate peaks for EA highly sensitive and EA less sensitive Mg2+-ATPase activities at 0.1 and 0.35 M NaCl, respectively. Polyacrylamide gradient gel electrophoresis of the samples from the peak-fractions of EA highly sensitive and EA less sensitive Mg2+-ATPase activities yielded prominent bands at 600 and 70 kDa, respectively. These results indicate that EA highly sensitive Mg2+-ATPase is solubilized and separated from EA less sensitive Mg2+-ATPase as a large enzyme molecule with anion-sensitive sites.

Animals↗
PubMed1991

The relationship between the anoxic sensitivity and the extent of sensitization by nitrous oxide.

Nitrous oxide reacts during irradiation to increase the yield of .OH, a radical many believe to be a major cause of lethality. Logically, one would expect N2O to be a radiation sensitizer. In some instances it is, while in others it is not. In some cases we can explain why N2O fails to sensitize; factors such as dose rate, cell concentration, buffer composition and ionic strength all influence when N2O will sensitize and, if it sensitizes, by what magnitude. Based on the results presented here with multiple strains of procaryotic and eucaryotic cells, we believe the anoxic sensitivity is another critical factor that governs whether N2O will sensitize. Our data, with data from the literature, show a relationship between the anoxic sensitivity and the N2O enhancement ratio. N2O does not sensitize in vitro unless the anoxic sensitivity (inactivation constant, k) is less than approximately 0.2 daGy-1.

Animals↗