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At least 37 records · Page 2Linked to original sources
PubMed1977

Adaptation to short-term respiratory effects of ozone in men exposed repeatedly.

To investigate whether adaptation which modifies some acute effects of ozone (O3) exposure can develop in humans, six male volunteers with respiratory hyperreactivity were exposed in a controlled environment chamber to 0.5 ppm O3 2h/day for 4 successive days under conditions stimulating ambient pollution exposures. One subject showed little measurable response, while five showed function decrement on exposure days 1-3 which was largely reversed by day 4. Symptom responses generally paralleled the physiological responses. These results suggest that at least some humans adapt to O3 exposure at concentrations occurring in severe community air pollution episodes, to the extent that obvious acute respiratory effects are prevented. Other adverse effects of O3 may not be prevented by this adaptation.

Adaptation, Physiological↗
PubMed1977

Establishing a normal peer as a behavioral model for developmentally delayed toddlers.

The present investigation demonstrated a systematic teaching procedure for establishing a normal toddler as a peer-model for three children showing delayed development, each one under 27 mo. of age. For each delayed subject, training consisted of adult-directed prompting and social reinforcement contingent upon the delayed children's imitations of material use and motor responses emitted by a normal peer. Within-subjects multiple-baseline designs across responses were used to demonstrate intrasubject control over imitative responding. Indices of stimulus and response generalization were assessed through having the peer-model present the trained responses along with untrained responses in a situation free of adult prompting and social reinforcement for imitative responding. Results indicated that the training in peer-imitation was successful for establishing the peer-model's behavior in a stimulus control relationship with the imitative responding of the delayed children. Moreover, the findings generally demonstrated transfer of training across stimulus situations and responses. Implications for educational programming with developmentally delayed children are discussed.

Behavior Therapy↗
PubMed1979

Physostigmine: effects on fear or defense responses in the rat.

Previous research had shown that the anticholinergic drug, scopolamine, decreased innate defensive responses of rats to a live cat or mechanical robot, and that the effects of scopolamine were attributable to actions of the drug on the central nervous system. In the present research, the anticholinesterase, physostigmine, which increases central cholinergic activity, caused an increase in the defense responses of male hooded rats. Physostigmine caused significantly more freezing and significantly more suppression of feeding and suppression of time near the aversive stimulus (ROBOT). Dose-response curves showed a positive, linear relationship between dose (0.025, 0.05, 0.1 and 0.2 mg/kg) of physostigmine and defense responses. The present results could not be attributed to general response suppression since the effects of physostigmine were situation-specific, i.e., the drug had no significant effect on behavior in the non-aversive or NO ROBOT condition. The present results were taken as further evidence of the involvement of cholinergic activity in the mediation of defense responses. The effects of cholinergic and anticholinergic drugs on the observable defense response of freezing were thought to have important implications for the large literature relating these drugs and avoidance responding.

Aggression↗
PubMed1992

Variations in patterns of DNA damage induced in human colorectal tumor cells by 5-fluorodeoxyuridine: implications for mechanisms of resistance and cytotoxicity.

We have previously shown that treatment of the HT29 human colorectal tumor (HCT) cell line with 100 nM 5-fluorodeoxyuridine (FdUrd) induces DNA fragments ranging from 50 kilobases to 5 megabases. The studies reported here were conducted to characterize the kinetics, concentration dependence, and pharmacologic specificity of this process and to determine if such fragmentation varies among HCT cell lines. HT29 and SW620 cells yielded similar fragment size distributions upon treatment with either FdUrd or CB3717 [a folate analog inhibitor of thymidylate synthase (TS)]. With either of these agents the SW620 line required higher drug concentrations or longer incubation times than HT29 cells to achieve a given level of fragmentation or cytotoxicity, even though the two cell lines are equally sensitive to FdUrd-induced TS inhibition. These data indicate that SW620 resistance is not due to a lesion in the events leading up to TS inhibition but it may be due to a difference in the steps following TS inhibition. Aphidicolin, a DNA polymerase inhibitor, did not cause substantial fragmentation or cytotoxicity in these two cell lines, demonstrating that the fragmentation response to the other two drugs is not a general consequence of DNA synthesis inhibition. A third HCT line, HuTu80, gave rise only to a smaller and more discrete population of DNA fragments, ranging from approximately 50 to 200 kilobases, following exposure to FdUrd. Similar patterns were seen in this line upon treatment with CB3717 or aphidicolin, indicating that this fragmentation pattern is not specific to TS inhibition and may be characteristic of a more general response than that seen in the other two cell lines. DNA fragments induced by FdUrd in HuTu80 cells did not degrade into smaller pieces, demonstrating that the process by which they are formed is distinct from apoptosis. We conclude that the responses of HCT cells to FdUrd-induced TS inhibition vary significantly, that these differences may reflect heterogeneity in the mechanism of DNA damage formation, and that, in some cases, FdUrd resistance may be due to alterations in the fragmentation process.

Cell Survival↗
PubMed1979

[Noise and pregnancy (author's transl)].

1. The response of women to aural and extra-aural effects of noise is not stronger than that of men. --2. General response of pregnant women does not differ from that of non-pregnant women or men under the impact of noise. --3. Foetal heart rate responses usually do not exceed generally known spontaneous variation of instantaneous foetal heart rate up to an equivalent permanent sound level of 90 dB (AI). Pulse noise produces startle reflex in the foetus. --4. For pregnant women in the GDR, the permissible limit in terms of equivalent permanent sound level of vocational environments has been reduced from 90 dB to 80 dB (AI), which reflects the extraordinary standards of health protection introduced for mother and child.

Female↗
PubMed1992

Prognostic indices in ovarian cancer. Their significance in treatment planning.

Ovarian cancer exhibits a wide spectrum of behavior, the effectiveness of therapies varies and the circumstances of patients differ. Better outcomes will require more selective treatment strategies considerate of these variables. 1. The need for treatment As long as outcome is affected more by disease than by treatment, survival will be determined by the bulk and growth-rate of residual tumor-prognostic factors reflect these. They indicate the need for treatment, but not whether benefit is likely. FIGO stage is the international standard, but this alone is inadequately predictive. Grade reflects virulence, but subjectivity has limited its usefulness. Newer quantitative pathology techniques (such as DNA ploidy) more reproducibly reflect behavior. Prognostic factors can be used to define subsets of patients at differing degrees of disease risk. 2. Efficacy of treatment No response predictors are yet of practical use in selecting primary chemotherapy on an individual basis. Generally, response is more likely if the tumor is less extensive and if dose and treatment frequency are higher. Monitoring biomarkers can more quickly identify those with a suboptimal response who may require a change or discontinuation of treatment. Re-laparotomy has limited usefulness. Response predictors for second-line treatment (e.g. the failure-free interval) are available and also have implications for new drug testing. 3. Suitability of treatment Advanced age or serious additional illness may render intensive treatment inappropriate. The informed patient's wishes are of prime importance. An evolving strategy of selective management is described.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1977

[Derivatives of 1,3-bis-(methlendioxyphenoxy)propane with antispastic activity].

A number of amines derived from 1,3-bis(3,4-methylen-dioxyphenoxy)propane have been prepared from 1,3-bis-(3,4-methylendioxy-phenoxy)propan-2-one. The acute toxicity and the activity of these compounds on isolated guinea pig ileum have been studied. The majority of the compounds showed clear antagonist activity towards BaCl2, histamine and acetylcholine contracting responses, generally grater than that of papaverine; on the contrary, their antagonist activity towards 5-HT responses was slightly lower.

Acetylcholine↗