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At least 487 records · Page 27Linked to original sources
PubMed1983

[Genetic study of saccharomycete yeast sensitivity to the lethal and mutagenic action of nitrous acid. III. Relation between mitochondrial genome variability and the unstable sensitivity of yeast cells to inactivation by nitrous acid].

The sensitivity of the yeast Saccharomyces cerevisiae to nitrous acid (NA) is significantly influenced by various spontaneous mutations of the mitochondrial (mt) genome as well as by the nuclear mutation mmg 1 leading to a decrease in the spontaneous mutability of the mt genome. The mmg 1 locus and the mt genome most probably interact and this nucleo-cytoplasmic interaction plays a role in determining the NA sensitivity of yeast cells. A significant subclonal variation of the NA sensitivity has already been reported for the strains under study. Here we show this variability to decrease significantly when the cells are devoid of the mt DNA or carry the mmg 1 mutation. These data suggest a direct relation between the unstable NA sensitivity and the variability of the mt genome.

Genes↗
PubMed1983

In vitro drug sensitivity studies of CFUc in chronic myelocytic leukemia: I. Suicide indices and busulfan sensitivity determinations during the chronic phase.

Serial clonogenicity studies employing an agar CFUc culture assay are being performed on cells from CML patients to determine if clonal growth, 3HTdR suicide indices (SI) and in vitro busulfan sensitivity are of prognostic significance in predicting blastic transformation. Initial studies performed on specimens obtained from 20 chronic phase patients were directed at determining whether blood and marrow cells differed in growth pattern, SI, and busulfan sensitivity and whether the cells giving rise to clusters differed from those forming colonies. In comparing marrow to blood cells, there was a correlation between the two with respect to the number of colonies produced and the sensitivity of the clonogenic cells to busulfan. By contrast the SI of blood and marrow clonogenic cells were not correlated. In both blood and marrow, colony forming cells had a higher SI and were more sensitive to busulfan than were cluster forming cells.

Adolescent↗
PubMed1976

Effect of six weekly transfusions on canine marrow grafts: tests for sensitization and abrogation of sensitization by procarbazine and antithymocyte serum.

We have previously shown that blood transfusions can immunize a dog and lead to rejection of a subsequent marrow graft despite lethal total body irradiation (TBI). Sensitization to histocompatibility antigens induced by two prior transfusions of whole blood could be overcome by a regimen of procarbazine and anti-thymocyte serum (ATS) preceding TBI. The current study investigated a) whether this regimen could abrogate sensitization induced by six weekly transfusions given from days --50 to --15 preceding a marrow graft, and b) whether platelet survival studies and two in vitro tests of immunity could predict marrow graft rejection. All donor-recipient pairs were histoincompatible, unrelated, and of different breed. Twenty-two recipients received platelet concentrate transfusions and eight received whole blood transfusions. Recipients were given 1200 R TBI and a graft of marrow and peripheral blood leukocytes from the transfusion donor on day 0. Three of 15 recipients (20%) given procarbazine, 12.5 mg/kg i.v. on days --8, --6, and --4, and ATS, 0.6 ml/kg subcutaneously on days --7, --5 and --3, Rejected their grafts, whereas 11 of 15 dogs (73%) not given procarbazine and ATS rejected their grafts (p less than 0.01). Serum lymphocytotoxic antibodies, peripheral leukocyte migration inhibition, and in vivo donor platelet recovery and survival were studied in those recipients receiving six weekly transfusions and in 18 other recipients receiving a single donor transfusion 3 months before marrow grafting. No significant correlation was found among these in vitro and in vivo tests of sensitization. Sensitization to marrow grafts was not reliably detected by the presence of cytotoxic antibodies or leukocyte migration inhibition. Platelet survival, however, was positively correlated with the results of marrow grafting in 12 of 15 (80%) evaluable recipients (p approximately 0.15).

Animals↗
PubMed1982

Nonspecific inhibition of in vivo tumor growth by allo-sensitized lymphocytes - requirement of radio-sensitive T-lymphocytes.

In previous papers we demonstrated with the Winn assay the WKA rat spleen cells sensitized to allogeneic tumor (AH-66 from Donryu strain) inhibited in vivo tumor growth of a syngeneic tumor (KMT-17) when early spleen cells (taken one week after the last immunization) were used. For the tumor inhibition by late spleen cells (2 weeks after the last immunization), further addition of inactivated homologous allogeneic cells was required. In the present study we examined with the Winn assay the nature of allo-sensitized spleen cells which nonspecifically inhibit in vivo growth of syngeneic tumors. Tumor inhibitory activity of early spleen cells was decreased by anti-rat T serum treatment. The same was true in tumor inhibition by late spleen cells stimulated with mitomycin-C treated AH-66 cells. Both of early and late spleen cells responsible for tumor inhibition are radio-sensitive, whereas KMT-17 sensitized T cells which specifically inhibited growth of homologous tumor cells belong to radio-resistant subpopulations.

Animals↗
PubMed1981

Investigation of insulin sensitivity in early diabetes III. The effect of a combined physical training and diet programme on body weight, serum lipids and insulin sensitivity in obese asymptomatic diabetics.

The effect of a physical training and low caloric diet (700 calories/day) for 4 weeks on insulin sensitivity in vivo, body weight and serum lipids was investigated in 10 obese asymptomatic diabetics (normal fasting plasma glucose and pathological glucose tolerance). Glucose tolerance and insulin secretion pattern were characterized by means of a 2h-glucose infusion test (12 mg/kg/min) primed by an initial injection of 0.33 g/kg glucose. Insulin responsiveness in vivo was estimated by means of a 1h-insulin infusion test (two 30-min. periods of 8 and 16 mU/kg insulin MC-Actrapid, primed by initial injection of 1 and 2 mU/kg, respectively). Under comparable steady-state insulin levels the decrease in plasma glucose and free fatty acids (FFA) was considered as estimate of insulin sensitivity in vivo. Physical working capacity (PWC170) was determined by means of a bicycle ergometer test in stepwise working loads. The training programme consisted of daily 15 min. bicycle ergometer training periods (75% of the maximal working capacity) in the morning and a 1 h mild physical training on a bicycle in the afternoon. After the combined training and diet programme the mean decrease in absolute and relative body weight amounted to 11.9 +/- 1.07 kg and 16.7 +/- 1.2%, respectively. There was a significant decrease of plasma triglycerides whereas the decrease in cholesterol was modest. Physical fitness increased by delta PWC170 of 31.1 +/- 11.6 W. In addition, the combined training and diet programme for 4 weeks resulted in a significant improvement of insulin sensitivity in vivo as indicated by an augmented insulin-induced decrease in plasma glucose and FFA (17.60 +/- 3.91%, vs 36.40 +/- 5.54%; p less than 0.05 and 35.90 +/- 6.95% vs 56.50 +/- 3.63%; p less than 0.05; respectively). Our findings provide direct evidence that physical training and low caloric diet enhance insulin sensitivity in vivo. From the practical point of view our results suggest the potential benefits of physical training in the treatment of obese asymptomatic diabetics.

Adult↗
PubMed1980

Drug sensitivity studies on clonal cell lines isolated from heteroploid tumor cell population. II. Sensitivity of clones growing in suspension cultures.

NK/S cell line and its clonal lines 6 and 10 were established in culture from NK/Ly mouse lymphoma. The clones differed from each other and from the parent line in chromosome pattern and growth rate. Clone 6 cells were polyploid and more sensitive to dianhydrogalactitol than the diploid clone 10 cells. However, clone 10 cells were more sensitive to adriamycin. A very small difference in sensitivity was found with vincristine. It was concluded that sensitivity of clones originating from the same parent population is drug-related.

Animals↗
PubMed1981

Induction of contact sensitivity and antigenic competition by the intravenous administration of contact sensitizers.

The effect of route of administration of contact sensitizers on the induction of antigenic competition between dinitrofluorobenzene (DNFB) and picryl chloride (PCl) and between oxazolone (Ox) and PCl was investigated. Antigenic competition (depressed contact sensitivity to PCl) was induced not only by painting with DNFB via various routes, such as intravenous (i.v.), oral or subcutaneous routes. Antigenic competition was abolished by the treatment with cyclophosphamide (CY) 4 days after i.v. injection of competing DNFB or Ox, and also by thymectomy 6 weeks prior to the injection of DNFB. These results suggest that thymus-derived suppressor cells may be involved in the antigenic competition induced by the i.v. injection of DNFB. Primary contact sensitivity (CS) was induced by painting of DNFB or Ox and also by i.v. injection of Ox. Although an i.v. injection of DNFB into normal mice did not induce CS, it induced a strong CS in the mice pretreated with CY 2 days prior to the injection of DNFB. Examination on the effect of dose of contact sensitizers on the induction of antigenic competition, primary CS and tolerance by painting or by i.v. injection of DNFB or Ox showed that the degree of antigenic competition has a closer relationship with CS, than with unresponsiveness.

Animals↗
PubMed1995

The differential expression of cytokeratin 18 in cisplatin-sensitive and -resistant human ovarian adenocarcinoma cells and its association with drug sensitivity.

DNA is the primary target of cis-diamminedichloroplatinum (cisplatin), but the drug also interacts with the cellular cytoskeleton composed of microtubules and intermediate filaments. It was found that the cisplatin-resistant 2008/C13* cell line contained markedly lower levels (6-fold) of cytokeratin 18, when compared to the cisplatin-sensitive 2008 cell line. Northern blot analysis revealed a markedly decreased level of cytokeratin 18 mRNA in the resistant cell line. Southern blot analysis of the DNA extracted from the two cell lines and then digested with HpaII and its methylation-sensitive isoschizomer, MspI, revealed no detectable differences in the methylation status of the cytokeratin gene. Neither 5-azacytidine (5 microM) nor retinoic acid (1 microM) treatment enhanced the expression of cytokeratin 18 in the resistant cell line. However, transfection of full-length cytokeratin 18 cDNA into the cisplatin-resistant 2008/C13* cells resulted in clones with increased levels of cytokeratin 18, which was accompanied in the majority of clones by a marked increase in their sensitivity to cisplatin. These results demonstrate that modulating the expression of an intermediate filament protein results in sensitization of a drug-resistant human ovarian cell line to cisplatin.

Adenocarcinoma↗
PubMed1995

Sunscreen intolerance. Contact sensitization, photocontact sensitization, and irritancy of sunscreen agents.

Reports of contact sensitization and photocontact sensitization induced by various sunscreening agents are reviewed. Current knowledge about the most often used sunscreening agents is summarized. The problems of cross-sensitization and sensitization in photodermatoses are discussed. Strategies for patch and photopatch testing, as well as immediate-type testing, are critically evaluated.

4-Aminobenzoic Acid↗
PubMed1994

Synaptic membrane responses to acute and chronic alcohol intoxication in high alcohol sensitive (HAS) and low alcohol sensitive (LAS) selectively bred rats.

HAS (high alcohol sensitive) and LAS (low alcohol sensitive) lines of rats have been selectively bred based on their differences in ethanol-induced sleep time. In the present study, the two lines were compared to examine another central effect of acute alcohol intoxication: namely, hypothermia. As the disturbances in membrane microorganization have been associated with the nervous system's sensitivity and tolerance to ethanol, the synaptic plasma membrane fluidity and acute sensitivity to ethanol were also evaluated by fluorescence polarization of DPH probes in the HAS and LAS rats. The two lines did not differ in the magnitude of their hypothermic response after acute injection of ethanol (3 g/kg body wt, i.p.). Although membranes in the HAS line were slightly more rigid than in the LAS line, the level of membrane disordering after acute ethanol addition was identical for the two lines in the region examined with the DPH probe. Following the chronic intoxication of the rats, the two lines developed tolerance to the hypnotic and hypothermic effects of ethanol. In the same way, a membrane resistance (i.e. tolerance) to the disordering effect of acute ethanol addition developed in the region probed with DPH. In general, the LAS line showed a more pronounced level of tolerance than the HAS line at both the functional and membrane level. These results suggest that different measures used to assess the depressant action of ethanol, such as sleep time, hypothermia or membrane disordering, may not be related and could indicate different genetic origins.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcoholic Intoxication↗
PubMed1996

Murine IL-12 is involved in Calmette-Guérin bacillus-induced sensitization and is by itself sufficient to sensitize mice to the lethal effects of human TNF1.

Human TNF, a specific agonist of murine (m)TNF-R55, is fairly harmless in healthy mice, but readily induces lethality in animals sensitized by a malignant tumor or a bacterial infection. We here report that IL-12 is both a necessary and sufficient mediator in Calmette-Guérin bacillus-induced sensitization to the lethal effects of hTNF. Evidence for this involvement is provided by the protection observed after anti-mIL-12 Ab treatment and by the fact that Calmette-Guérin bacillus-induced sensitization can be mimicked by repetitive mIL-12 administration. IL-12 exerts this effect by inducing IFN-gamma in NK cells. Tumor-induced sensitization, however, does not seem to involve mIL-12.

Animals↗
PubMed1997

Differential development and characterization of rapid acute neuronal tolerance to the depressant effects of ethanol on cerebellar Purkinje neurons of low-alcohol-sensitive and high-alcohol-sensitive rats.

Rapid acute neuronal tolerance (RANT) to the depressant effects of ethanol (EtOH) is a desensitization of EtOH-induced depression of neuronal firing that develops over the first 5 to 7 min of EtOH exposure. This phenomenon has been hypothesized to play a role in acute behavioral insensitivity to EtOH and is expressed by cerebellar Purkinje neurons in animals selectively bred for insensitivity to EtOH-induced ataxia, such as low-alcohol-sensitive (LAS) rats and short-sleep mice. Purkinje neurons of animals bred for high sensitivity to EtOH-induced behavioral ataxia, such as high-alcohol-sensitive (HAS) rats and long-sleep mice, only infrequently express such acute tolerance to EtOH-induced depression of neuronal activity. However, because higher EtOH doses are required to depress Purkinje neuron activity in LAS rats than in HAS rats, it was not known whether the higher EtOH doses that depress LAS neurons would also induce RANT to EtOH in HAS rats, which were generally not exposed to such high EtOH doses in previous studies. Furthermore, the conditions for development and maintenance of RANT to EtOH had not been characterized. We found that RANT to EtOH-induced depression of cerebellar neurons principally developed within 5 min of EtOH application and recovered within 20 min of the last EtOH exposure and that neurons in HAS rats did not develop acute tolerance to the higher EtOH doses that were effective in LAS rats. We conclude that this rapid tolerance contributes to the acute EtOH sensitivity difference between LAS and HAS rats.

Action Potentials↗
PubMed1997

[Sensitized photomodification of DNA with binary systems. II. Spectral photosensitivity. One- and two quantum sensitization].

The efficiency of the photomodification of target single-stranded DNA with a decanucleotide derivative of p-azidotetrafluorobenzamide (direct photomodification) and with its complexes with decanucleotide derivatives of pyrene complementary to the adjacent segment of the target (sensitized photomodification) was studied as a function of the wavelength of long-wave UV light. The sensitized photomodification occurs mainly by singlet-singlet energy transfer from pyrene to azide in their complementary complex, which allows a significant increase in the rate and level of photomodification. When irradiation occurred simultaneously in the UV and visible regions (365-580 nm), two-photon triplet-triplet sensitization was revealed for the first time, which leads to a still greater acceleration of the target modification and a change of its site-direction from the G11 to T13 residue. The change of the mode of sensitization depending on the irradiation conditions allows the regulation of the reactivity of the binary system of oligonucleotide derivatives without altering their composition.

Autoradiography↗
PubMed2003

Trace determination of arsenic species by capillary electrophoresis with direct UV detection using sensitivity enhancement by counter- or co-electroosmotic flow stacking and a high-sensitivity cell.

Stacking techniques used independently and also with a high-sensitivity cell (HSC) were employed to optimise sensitivity and detection limits in the direct photometric detection of the following eight arsenic species by capillary zone electrophoresis (CZE): arsenite, arsenate, monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), 4-hydroxy-3-nitrophenylarsonic acid (Roxarsone), p-aminophenylarsonic acid (p-ASA), 4-nitrophenylarsonic acid (4-NPAA), and phenylarsonic acid (PAA) (target analytes). The stacking mechanisms, optimised stacking and separation conditions, and concentration sensitivity enhancement factors were discussed and compared for (i) normal stacking mode (NSM, sometimes also referred to as field-amplified stacking) in an uncoated fused-silica capillary in the counter-electroosmotic flow (EOF) mode, (ii) large-volume sample stacking (LVSS) with polarity switching, and (iii) the less often applied stacking method of co-EOF NSM stacking with EOF reversal using a poly(diallydimethylammonium chloride) (PDDAC)-coated capillary. The optimal injection volumes were 7.4, 60 and 17.2% of the total capillary volume, for the above three methods, respectively. LVSS with polarity switching gave the lowest limit of detection (LOD). The use of the HSC further reduced the LOD of each target analytes by a factor of 5-8 times. By combining LVSS and HSC, LODs of the target analytes could be reduced by a factor of 218-311, to 5.61, 9.15, 11.1, and 17.1 microg/L for As(III), DMA, MMA, and As(V), respectively. The method was demonstrated to be applicable to the determination of the target analytes in tap water and lake water, with recoveries in the range of 89.4-103.3%.

Arsenic↗
PubMed1996

Sensitivity of high-speed "perfusion-sensitive" magnetic resonance imaging to mild cerebral ischemia.

This study assessed the sensitivity of contrast-enhanced dynamic echo-planar imaging to subtotal stenosis of the middle cerebral artery as a model of mildly compromised cerebral blood supply. Dynamic data was analyzed in terms of the relative cerebral blood volume (rCBV) and bolus peak arrival time (BPAT), and the prognostic utility of these parameters was compared with measurements of the regional apparent diffusion coefficient of water (ADC) with the goal of identifying tissue at risk of future infarct. Dynamic echo-planar MRI in conjunction with bolus administration of a magnetic susceptibility contrast agent was used in a cat model of acute, unilateral cerebral ischemia, induced by partial occlusion (stenosis) of the right middle cerebral artery. The contrast agent transit was analyzed in terms of the regional time of arrival of the peak bolus-induced signal loss as well as the time integral of agent concentration. Pixel-by-pixel maps of cerebrovascular parameters (rCBV, BPAT) were constructed along with spatial maps of the ADC, derived from diffusion-weighted MR images at the same anatomical level. Arterial stenosis was maintained for a 6 h period, after which histological determination of tissue viability was obtained. Maps of BPAT showed sensitivity to mild flow perturbations not detectable from cerebral blood volume estimations from the same bolus injection or from determinations of the apparent diffusion coefficient of water. Of nine animals subjected to subtotal stenosis, BPAT identified compromised tissue in all nine after 1 h of stenosis. No animals had differences in rCBV or ADC at this point. Stenosis was maintained for 6 h in 7 of the cats. After 6 h, two cats had developed identifiable injury on ADC and rCBV maps. Of the remaining five, where rCBV and ADC appeared normal even after 6 h, three exhibited abnormal histological staining, whereas two indeed appeared normal. In the other two cats where initial subtotal stenosis was later made total, the anatomical region identified as "compromised" during stenosis, by the appearance of delayed bolus peak arrival, matched the area of subsequent infarct after total occlusion of the same vessel. Echo planar imaging in conjunction with bolus administration of a magnetic susceptibility contrast agent appears sensitive to mild perturbations to blood supply. These perturbations may not be resolved on synthesized maps of relative cerebral blood volume or apparent diffusion coefficient. Although "compromised" blood supply does not necessarily lead to infarct (over the 6-h course of this study), it may represent tissue particularly at risk of infarct in the event of further insult.

Animals↗
PubMed1997

The sensitivity of new color systems in blood-flow diagnosis. The maximum entropy method and angio-color-comparative in vitro flow measurements to determine sensitivity.

BACKGROUND: Two new blood-flow-diagnosis techniques have recently been developed as supplements to the established color techniques: the MEM (maximum entropy method) technique and color flow amplitude (power Doppler). These are capable of representing blood flow in distinctly more slowly flowing areas than is possible with the conventional Doppler technique. METHODS: Both methods make use of the Doppler technique in part, yet analyze the reflected signal in a different manner, in so doing optimizing the relation between the noise and the signal. Measurements were obtained on two anatomic flow models to test the sensitivity of both techniques under slow flow conditions. RESULTS: The slowest flow the MEM technique was capable of recording was 0.5 mm/s, albeit utilizing a 5-MHz transducer for the MEM technique and a 10-MHz transducer for the angio technique. One may thus assume that the MEM technique would be still more sensitive when utilizing a 10-MHz transducer. The advantage of the MEM technique is its real-time flow representation: The angio technique requires a few seconds of acquisition time. This could have serious consequences during clinical utilization. Doppler sonography was merely capable of detecting a minimum flow velocity of 15 mm/s. The angio technique is less dependent on the angle during flow representation than the MEM technique. CONCLUSIONS: The distinctly higher sensitivity of these two new color techniques offers new possibilities in the clinical sector as far as the perfusion diagnosis of organs and tumors is concerned.

Angiography↗
PubMed1992

Contrast sensitivity during horizontal visual pursuit: dynamic sensitivity functions.

The contrast sensitivity functions of college students for grating targets presented at angular velocities of 0, 30, 60, and 90 deg s-1 were determined for target durations of 200 and 600 ms. The most pronounced effects of target movement were evident at the mid to high spatial frequencies in which sensitivity was markedly reduced as velocity increased. These adverse effects were greatest in the 200 ms condition, in which performance was largely limited to the saccadic eye movement system. In the 600 ms condition, in which both saccadic and smooth pursuit eye movements were possible, contrast sensitivity for the low-frequency target actually improved significantly for the 30 and 60 deg s-1 targets, whereas only adverse effects of target motion were found for targets of mid and high spatial frequencies. The results are discussed in terms of the limitations of traditional visual assessment procedures and the practical and theoretical benefits of conceptualizing the joint effects of target composition and target movement.

Adult↗
PubMedDate not supplied

Detection of Chlamydia trachomatis in men. Sensitive tests for sensitive urethras.

The value of examining the centrifuged deposit from a first pass urine sample by an amplified enzyme-linked immunosorbent assay (ELISA) to detect Chlamydia trachomatis was assessed. The results were compared with those obtained by examining a urethral smear with a direct fluorescent antibody (DFA) test (MicroTrak; Syva, Palo Alto, CA). When the first pass urine sample yielded positive results for the IDEIA, but results of the DFA test of the corresponding urethral sample were negative, the remaining centrifuged deposit from the urine sample was examined by the DFA test. If results of this DFA test were positive, the IDEIA result was regarded as a true positive. Paired samples were collected by nursing staff from 190 men attending a clinic for sexually transmitted diseases (STDs). The quality of sampling thus reflected routine practice. The sensitivity of the IDEIA using first pass urine samples was 90% (37/41), and the sensitivity of the DFA test of urethral samples was 83% (34/41). The adoption of testing of first pass urine samples for the detection of C. trachomatis in STD clinics will not lead to a decrease in sensitivity for detecting C. trachomatis and will be more acceptable to patients than urethral swabbing.

Adult↗