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At least 19 recordsLinked to original sources

PubMed1978

Changes in the cyclic nucleotides of rat thyroid, pituitary and plasma caused by methylthiouracil treatment.

Changes in the content of cyclic nucleotides (cAMP and cGMP) and related enzyme activities were observed in the rat thyroid, pituitary and plasma during the prolonged increase of endogenous TSH produced by treatment with methylthiouracil (MTU). Experiments were performed after 4 weeks treatment with MTU. The wet weight and cAMP content per wet weight of the thyroid increased 3 and 1.4 times respectively, but cGMP showed a slight decrease. Pituitary weight increased 1.3 times, but cAMP and cGMP content did not change. The cAMP level in plasma also increased about 1.3 times, but cGMP did not increase. The cAMP-phosphodiesterase activity in the thyroid, pituitary and plasma was increased 1.9, 1.4 and 1.3 times respectively after MTU treatment, while cGMP-phosphodiesterase showed no significant change. ATPase activity in the thyroid and pituitary was also increased more than 1.5 times after MTU treatment, while 5'-nucleotidase activitity decreased remarkably. These data indicate that the metabolism of the cyclic nucleotide system in the thyroid is stimulated by TSH.

Adenosine Triphosphatases↗

PubMed1976

Noradrenergic subsensitivity and supersensitivity of the cerebral cortex after reserpine treatment.

Changes in the sensitivity of the cyclic adenosine 3', 5'-monophosphate response of rat brain cerebral cortical slices to norepinephrine were measured in vitro after the rats received i.p. injections of reserpine (1 mg/kg). Subsensitivity was evident 1 hour after a single reserpine treatment compared with saline controls. However, if reserpine was injected daily for 4 days followed by 1 day without reserpine treatment, a supersensitive response to NE was shown compared to the controls. Mean pD2 values are presented to illustrate the shifts of the dose-response curves after reserpine treatment. The present work demonstrated the induction of noradrenergic sub- and supersensitivity to norepinephrine in rat cerebral cortical slices after acute and 4-day reserpine treatment, respectively.

Animals↗

PubMed1976

Characteristics of three strains of feline fibrosarcoma virus grown in cat and marmoset monkey cells.

Two strains of feline fibrosarcoma virus (ST-FeSV and GA-FeSV) were found to induce tumors in cats and marmosets, and to transform feline and marmoset cells in vitro after primary inoculation. A third strain (SM-FeSV) failed to induce tumors or transform marmoset cells after primary inoculation; however, when SM-FeSV-injected marmoset cultures were passed 26 times in vitro, the cell cultures released infectious virus which transformed marmoset fibroblasts but still failed to induce tumors in marmosets. ST-FeSV induced mainly round-cell type transformation (r foci), GA-FeSV induced predominantly mixed round-fusiform cell type transformation (fr foci), and SM-FeSV induced r and fr type foci with a higher proportion of fusiform cells in the fr foci than seen with GA-FeSV. Transforming virus was obtained from r or mixed r/fr foci of ST-FeSV but not from fr foci; heat treatment changed the virus from producing almost exclusively r type foci to inducing an increased number of fr foci. Passage of FeSV in cat cells yielded viruses with a higher ratio of infectivity for feline vs marmoset cells, while passage of FeSV in marmoset cells yielded virus with a relatively higher infectivity ratio for marmoset cells; the three strains differed in the degree of change in the infectivity ratio. Despite the alteration of host range of SM-FeSV propagated in marmoset fibroblasts, the virus retained feline P-30 antigen by CF and FA assays. Neutralization tests did not indicate but also did not exclude an alteration of the surface antigens of ST-FeSV or SM-FeSV propagated in marmoset fibroblasts. The alteration of the relative infectivity of FeSV during passage in marmoset cells may be due to: (1) the selection of a variant present in the original heterogenous uncloned population; (2) mutation; or (3) recombination with some marmoset genetic material, possibly an as yet unidentified endogenous marmoset virus.

Animals↗

PubMed1978

Effect of immunosuppression on the growth of six murine tumors.

Mice have been immunosuppressed with cyclophosphamide, cortisone-acetate, irradiation, or Ehrlich ascitic fluid (EAF) and then grafted with Ehrlich tumor or with one of the following strain-specific tumors: thymoma, methylcholanthrene-induced fibrosarcoma, B-16 melanoma, lymphatic leukaemia, and myeloid leukaemia. Immunosuppression of the host influenced very differently the growth of transplanted malignancies. The growth of thymoma and of Ehrlich tumor was regularly enhanced. The growth of fibrosarcoma and of melanoma, on the other hand, was retarded in mice pretreated with EAF and X-rays, or remained unchanged in mice pretreated with drugs. Leukaemia growth was not influenced by any immunosuppressive treatment; the only exception was enhanced growth of lymphoid leukaemia in animals pretreated with EAF. Thus different tumors grew differently in animals immunosuppressed by the same immunosuppressive agent, while different immunosuppressive treatment changed the growth of one particular tumor always in the same way. From this we concluded: (1) there is no rule as to how immunosuppression of the host will influence tumor growth; and (2) the way in which the malignant growth will be changed depends mainly upon the type of the tumor and probably not very much upon the type of immunosuppressive treatment.

Animals↗

PubMed1979

Fine structural evidence of increased endothelial permeability in chronic lathyrism.

The endothelium of the thoracic aorta of Wistar rats intoxicated with Beta-Aminopropionitrile (BAPN) for 9 weeks was studied. The animals were sacrificed at intervals, from the first to the 9th week of the treatment and 1, 2 and 3 months after the end of the treatment. Changes in the endothelial cells were studied by electron microscopy after staining with uranyl acetate and lead citrate, after impregnation with lanthanum. BAPN increased endothelial permeability, pinocytosis was more active in treated rats than controls, the intercellular junctions widened and cytoplasmic lesions with cell necrosis occurred. These intimal changes were comparable to those observed in man during ageing and in arteriosclerosis.

Animals↗

PubMed1976

The action of a binary nonionic detergent on a kidney membrane fraction.

The disruption of a kidney cortex microsomal membrane preparation by a binary, nonionic detergent, was followed by using as markers, the changes in total protein content, and (Na+, K+)-ATPase in a supernatant fraction. Both markers responded similarly to changes in pH, microsome concentration and detergent concentration, but responded differently for time-dependent studies. The (Na+, K+)-ATPase activity was increased 2.2-fold (76.1 mumoles Pi/mg protein/h, 95% ouabain-sensitive) by a single detergent treatment and 3.5-fold (92% ouabain-sensitive) by a sequential detergent treatment. Changes in the critical micelle concentration (cmc) were observed for varying detergent and protein concentrations, which suggest interactions of monomeric detergent with the membrane. The peak of (Na+, K+)-ATPase activity occurred above the cmc which suggests the participation of micelles in releasing the enzyme from the membranes. Hill plots of the protein released as the detergent concentration was varied showed a change in the slope near the cmc indicating a four-fold increase in the binding of detergent to membranes as the detergent concentration is increased above the cmc. These results suggest that the disruption of membranes by detergent involves the binding of detergent monomers to the membrane followed by the formation of co-micelles of the detergent with segments of the membrane to complete the separation process.

Adenosine Triphosphatases↗

PubMed1978

Acute effects of cholestyramine on serum lipoprotein concentrations in type II hyperlipoproteinaemia.

Twelve subjects with primary type IIA hyperlipoproteinaemia were treated with cholestyramine under metabolic ward conditions in order to study the timing of effects of different serum lipoprotein classes. After 1 day's treatment changes occurred in all 3 classes, i.e., very low (VLDL), low (LDL) and high (HDL) density lipoprotein classes. VLDL increased abruptly and remained constant during treatment. The ratio of cholesterol/triglycerides decreased suggesting the formation of larger particles. LDL cholesterol decreased continuously suggesting a different mechanism behind this effect than that on VLDL. LDL triglyceride remained constant indicating a relative increase of LDL1. HDL cholesterol decreased while HDL triglycerides increased. All changes made the lipoprotein pattern more "type IV-like". The findings were in agreement with an increased formation of VLDL and an increased flux of lipoprotein through the cascade VLDL-IDL-LDL1-LDL2.

Aged↗

PubMed2026

Assessing time to symptomatic progression, a patient-relevant efficacy endpoint, in the MARIPOSA study in non-small cell lung cancer.

INTRODUCTION: In the phase 3 randomized MARIPOSA study, amivantamab and lazertinib combination therapy demonstrated improved progression-free survival (PFS) and overall survival (OS) versus osimertinib in participants with previously untreated, epidermal growth factor receptor-mutated advanced non-small cell lung cancer. Time to symptomatic progression (TTSP) was introduced to assess clinical worsening and complement endpoints that investigate radiographic disease progression and patient-reported outcomes. TTSP provides an easily interpretable measure of disease-specific symptom worsening to further support patient experience. METHODS: In MARIPOSA, TTSP was quantitatively assessed as a secondary efficacy endpoint and defined as the time from randomization until participants experience disease-specific symptom worsening requiring a clinical intervention or treatment change, or death. To evaluate the impact of amivantamab and lazertinib on TTSP considering its established OS benefit against osimertinib, an exploratory analysis censoring death events was performed. RESULTS: At the final protocol-specified OS analysis (median follow up: 37.8 months), median TTSP was 43.6 months with amivantamab and lazertinib versus 29.3 months with osimertinib (hazard ratio [HR]: 0.69; 95% confidence interval [CI]: 0.57-0.83; p < 0.0001). Amivantamab and lazertinib reduced deaths following a TTSP event compared to osimertinib. A strong correlation between TTSP and PFS or OS was observed. CONCLUSIONS: Amivantamab and lazertinib significantly delayed TTSP versus osimertinib. TTSP offers a clinician-validated measurement of disease-specific symptom worsening, capturing symptoms perceived by patients that prompt clinical action. TTSP is highly correlated with PFS and OS, providing complementary insights alongside traditional endpoints. TTSP enhances understanding of treatment benefit and supports informed clinical decision-making by integrating patient experience.

Humans↗

PubMed2026

Targeted reflex RNA sequencing for enhanced variant classification on exome and genome sequencing improves patient outcomes.

RNA sequencing (RNA-seq) has been utilized to provide functional evidence regarding the impact of splicing variants. This study explores the utility of targeted reflex RNA-seq to inform classification of predicted splicing variants identified through clinical exome sequencing (ES) and genome sequencing (GS). A retrospective analysis was conducted on consecutive ES/GS cases completed at a single center in which targeted reflex RNA-seq was performed following identification of eligible variants. There were 131 cases (4.1%) that had at least one RNA-seq eligible variant reported, with eight of these cases having two unique eligible variants. Of the 139 eligible variants, 125 were classified as variants of uncertain significance (VUS). Sixty-four cases had targeted reflex RNA-seq completed with 27 cases having at least one variant reclassified (42.2%). After reclassification, 23 cases had positive results, and two cases had a likely diagnosis of an autosomal recessive condition. Clinical outcomes data regarding positive RNA-seq cases showed that 71% (10/14) had clinical management changes and 43% (6/14) had treatment changes. Incorporation of targeted reflex RNA-seq analysis into the diagnostic pipeline of rare diseases enhances variant classification and resolves uncertainty regarding predicted splice variants, leading to an estimated 1.6% increase in diagnostic yield of clinical ES/GS.

Journal Article↗

PubMed2025

Molecular features influencing clinical outcome of advanced HER2-positive gastric cancer receiving trastuzumab plus chemotherapy.

BACKGROUND: Less than half of the human epidermal growth factor receptor 2 (HER2)-positive gastric cancer (GC) patients respond to trastuzumab plus chemotherapy, and the outcomes are unsatisfactory. Understanding the underlying mechanisms remains crucial for identifying patients who are more likely to benefit from treatment. PATIENTS AND METHODS: We performed targeted DNA sequencing on paired pre-treatment and progressive tumour tissues from 22 HER2-positive advanced GC patients undergoing first-line treatment with trastuzumab and chemotherapy. Clinicopathological and genomic characteristics were assessed for the correlation with clinical outcomes. RESULTS: A performance status (PS) of 0-1 was associated with improved progression-free survival (PFS) and overall survival (OS) than a PS of 2. Poorly differentiated tumours exhibited shorter PFS than moderate or moderate-poor ones. Pre-treatment amplification of MYC or TOP2A gene was association with increased PFS, and suggested a potential benefit for OS. Patients with higher tumour mutation burden (TMB) experienced significantly worse PFS, while higher chromosome instability (CIN) appeared to be correlated with longer PFS. Compared to non-responders, responders had a higher CIN but similar TMB and intratumoural heterogeneity (ITH). PS and MYC amplification emerged as independent factors related to PFS according to multivariate survival analysis. Additionally, after treatment, TMB significantly increased in non-responders, while CIN significantly decreased in responders. CONCLUSIONS: Pre-treatment MYC amplification and PS were independently associated with clinical outcomes in HER2-positive advanced GC patients treated with first-line trastuzumab plus chemotherapy. Dynamic post-treatment changes in TMB and CIS provide valuable insights into the relationship between therapeutic response and distinct evolutionary trajectories.

Humans↗

PubMed2026

Relationships among mechanisms in psychosocial treatments for chronic pain: mechanism to mechanism lagged effects and relationships with outcomes.

Results suggest that psychosocial treatments for chronic pain work via several mechanisms, and that they often do so to similar degrees and in similar ways. Extant research, however, has focused on individual and/or independent effects of mechanisms on outcomes. Whether successful outcomes are also partly because of sequential and meaningful relationships among and between mechanisms-mechanism-to-mechanism effects-has not been examined. Secondary analyses were conducted of an RCT that compared cognitive therapy, mindfulness-based stress reduction, and behavior therapy to treatment as usual in a sample (N = 521) of people with chronic low back pain. Results of hierarchical linear modeling revealed that (1) Treatment Condition × Mechanism interactions predicting changes in other mechanisms were nonsignificant; (2) lagged prior session mechanism changes predicted next session changes in another mechanism; (3) lagged relationships between pain catastrophizing and pain self-efficacy were reciprocal, whereas links between lagged pain catastrophizing and mindfulness changes and lagged pain catastrophizing changes and behavioral activation changes were unidirectional; and (4) individual differences in the strengths of mechanism-to-mechanism relationships predicted pre- to post-treatment changes in outcomes. Results reveal heretofore hidden therapeutic processes that cognitive therapy, mindfulness-based stress reduction, and behavior therapy may share. Namely, that mechanism-to-mechanism lagged effects do indeed emerge beyond mechanism-to-outcome effects. Findings show not only that mechanisms may change in definable sequences relative to each other but that individual differences in the strengths of mechanism-to-mechanism relationships may themselves be predictive of outcomes.

Humans↗

PubMed2026

Comparison of analgesic treatments used for ankle sprains in the emergency department.

BACKGROUND: Ankle sprains (ASs) account for approximately 5% of emergency department visits and 40% of all sports-related injuries, causing significant pain and restriction in the range of motion (ROM). This study aims to observe the clinical outcomes of early administration of intravenously administered paracetamol, ibuprofen, and dexketoprofen, which are frequently used in emergency department practice for ASs. For this purpose, pain monitoring and ROM measurements were performed to demonstrate the effectiveness of early functional analgesia. METHODS: This prospective, randomized, double-blind study was conducted between December 2023 and May 2024 on patients diagnosed with grade 1-2 ASs in the emergency department. Patients were divided into three groups and received intravenous dexketoprofen (Group D, n=52), paracetamol (Group P, n=52), and ibuprofen (Group I, n=51). Pain assessment was performed using the numeric rating scale (NRS) and the Wong-Baker FACES Pain Scale (WBS). ROM was evaluated by measuring dorsiflexion ROM (d-ROM) and plantar flexion ROM (p-ROM) angles using a semicircular goniometer. Pre-treatment and 1-h post-treatment measure-ments were compared. RESULTS: In the post-treatment pain assessment, no significant difference was observed between the groups in terms of NRS scores (p=0.352); however, Group I had the lowest WBS scores (p<0.001). Nevertheless, in all three groups, post-treatment pain scores (NRS and WBS) were significantly lower compared to pre-treatment values (p<0.001). Regarding ROM, pre-treatment d-ROM and p-ROM values were similar among the groups (p=0.196) and p=0.287, respectively). Post-treatment measurements revealed that d-ROM was lower in Group I (p=0.034), whereas p-ROM was higher (p=0.011). However, in all groups, ROM values significantly improved after treatment compared to baseline (p<0.001). When pre- and post-treatment changes (Δ) in pain scores and ROM values were compared, no statistically significant differences were found between the groups (ΔNRS p=0.264, ΔWBS p=0.965, Δd-ROM p=0.099, Δp-ROM p=0.073). CONCLUSION: Paracetamol, ibuprofen, and dexketoprofen demonstrated similar efficacy in reducing pain and improving ankle joint ROM during the acute phase of ASs. These findings suggest that the early initiation of analgesic treatment in ASs contributes to clinical recovery.

Humans↗

PubMed2026

Transcranial Magnetic Stimulation for Patients with Exposure Therapy Resistant Obsessive-Compulsive Disorder (TETRO): Study Protocol for a Multicenter Randomized Controlled Trial.

BACKGROUND: Obsessive-compulsive disorder (OCD) is a disabling mental disorder, characterized by obsessions, compulsions, and substantial morbidity. Approximately 50% of adults with OCD fail to achieve satisfactory outcomes from first-line treatments, such as exposure therapy with response prevention (ERP), with or without medication. This leads to chronic social, educational, and occupational impairment. While invasive procedures such as deep brain stimulation are available for severe, treatment-refractory cases, a need remains for less invasive alternatives. Repetitive transcranial magnetic stimulation (rTMS), a noninvasive intervention, shows promise in reducing OCD symptoms. Unlike in depression, rTMS is not yet reimbursed for OCD in the Dutch healthcare system. OBJECTIVE: This study examines the efficacy and cost-effectiveness of low-frequency (1Hz) rTMS targeting the presupplementary motor area (pre-SMA) compared to sham rTMS as an adjuvant treatment to ERP in adults with OCD with inadequate response to first-line treatment. METHODS: A total of 250 adults with OCD will be enrolled in this multicenter randomized controlled trial. Participants will be randomly assigned to ERP combined with either active or sham 1Hz rTMS over the pre-SMA. Treatment is administered 4 times weekly for at least 5 weeks (20 rTMS-ERP sessions), with optional extension of 1 to 2 weeks, up to 28 rTMS-ERP sessions. Clinical assessments occur at baseline, weekly during treatment, posttreatment, and at 3, 6, and 12 months follow-up. Participants undergo pre- and posttreatment (functional) (MRI) scans, including a symptom provocation task. Blood sampling takes place pre- and posttreatment and at 3-month follow-up. The primary outcome is OCD severity at posttreatment, as measured by the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS). Secondary outcomes include functional improvement, quality of life, and societal costs. Pretreatment symptom profiles, genotype, and brain network topology will be analyzed as predictors of response and relapse risk. Pre-to-post treatment change in blood-based and magnetic resonance (MR)-based neuroplasticity markers will help explore differential mechanisms between ERP alone and combined rTMS-ERP. We expect that the verum rTMS protocol will be cost-effective compared to sham-rTMS. RESULTS: Recruitment started in April 2022, and as of February 2026, 201 participants have been enrolled. Posttreatment assessments are projected to be completed in December 2026, with final one-year follow-up evaluations anticipated by the end of 2027. CONCLUSIONS: To our knowledge, this study is the first adequately powered randomized controlled trial examining efficacy, cost-effectiveness, and mechanism of action of rTMS for OCD as adjuvant therapy to ERP. In case of efficacy and/or cost-effectiveness, it will pave the way for rTMS as insured health care for adults with OCD in the Netherlands, and possibly other European countries. Furthermore, this trial will provide insight into the mechanisms of treatment response to intensive ERP, with and without adjunctive rTMS, as well as potential side effects, individual variability, and long-term outcomes in adults with OCD.

Humans↗

PubMed1979

Effect of Sar1-ala8-angiotensin II on blood pressure and renin in Bartter's syndrome, before and after treatment with prostaglandin synthetase inhibitors.

Three patients suffering from Bartter's syndrome were studied before and after 5 days of treatment with the prostaglandin synthetase inhibitors, aspirin and indomethacin. Saralasin was given by intravenous infusion in increasing doses from 0.6 to 42 micrograms/min.kg/BW. During saralasin infusion a blood pressure reduction was observed in all patients. Aspirin treatment did not affect this response and nor did it affect other manifestations of the syndrome. Indomethacin treatment changed the blood pressure response to saralasin in such a way that the blood pressure was increased in one patient and was unchanged in the other. Indomethacin also tended to normalize other features of Bartter's syndrome, such as the hyperreninaemia and angiotensin unresponsiveness, but did not affect the hypokalaemia. The saralsin effect on blood pressure is thus evidently inversely related to the prevailing activity of the renin-angiotensin system in this condition also, and the patients obviously depended on the renin-angiotensin system to maintain their blood pressure. Our findings, together with data in the literature, indicate that angiotensin unresponsiveness of the vascular bed is not a primary feature in Bartter's syndrome. Chloride loss is currently thought to be the basic abnormality and this may link the Bartter's syndrome with other diseased states characterized by chloride loss, such as the syndrome of habitual vomiting and chronic treatment with loop diuretics.

Adolescent↗

PubMedDate not supplied

[Change in the sensitivity of staphylococci to phages and the possible methodological procedures in their phage typing].

In a number of pathogenic staphylococci present in a food product that has been subjected to a mild heat treatment changes in the phage pattern were studied. The heat was found to produce in a number of staphylococcal strains a change in the sensitivity to phages, as a result of which phage patterns may assume different forms without losing their pathogenic and enterotoxic properties. This may lead to an erroneous interpretation of the results subsequent to an epidemiological study of staphylococcal intoxications.

Bacteriophage Typing↗

PubMed1975

[Pseudohypoparathyroidism: investigations of the serum parathyroid hormone level, pte resistance and urinary camp excretion before and during vitamin d treatment (author's transl)].

Pseudohypoparathyroidism (PHP) is a hereditary disorder with typical dysmorphic signs, oligophrenia and clinical and laboratory signs of hypoparathyroidism, which is resistant to parathyroid extract (PTE). Pseudopseudohypoparathyroidism (PPHP) is a genetically identical, partial form of PHP without hypoparathyroidism. Many hypotheses exist to explain the pathogenesis of these disorders: Albright and coworkers first demonstrated the PHP is caused by an inability of the renal tubules to respond to parathyroid hormone (PTH). Later hypotheses proposed a general defect in phosphorus transport, defects in the synthesis of PTH, the existence of antibodies to this hormone or hyperthyrocalcitonism. The possibility of measuring PTH in the peripheral serum by radioimmunoassay and improved knowledge of the role of cyclic adenosine monophosphate (cAMP) as a mediator of the action of PTH were necessary to explain the pathogenesis of PHP and PPHP. Three children suffering from PHP and two adults with PPHP were investigated as follows: measurements of PTH in the peripheral serum; assays of PTH levels during artificial hypercalcaemia; serial assays of calcium, phosphorus and PTH levels during vitamin D treatment; changes in the Ellsworth-Howard tests indicative of PTE resistance during vitamin D treatment and measurements of urinary cAMP excretion before and during vitamin D therapy. The following results were obtained: Secondary hyperparathyroidism in PHP, which could be suppressed by hypercalcaemia; normal levels of PTH in PPHP; normalization of serum calcium, phosphorus and PTE during treatment with vitamin D; abnormally low basal levels of cAMP in PHP, which could not be stimulated by PTE either before or during vitamin D treatment. The results of these investigations confirm Albright's hypothesis of endorgan resistance to PTH in PHP. This is caused by the inability of the PTH-sensitive adenylcyclase-system to mediate the action of PTH on its target cells. This is responsible for the distrubances in calcium and phosphorus metabolism and for secondary hyperparathyroidism. While this mediatorial defect seems to be total or almost total in PHP, a partial defect has to be assumed in PPHP.

Adenylyl Cyclases↗

PubMed1978

The effects of some stimulants and anti-psychotic drugs on urinary unconjugated tyramine levels in the rat.

The effects of intraperitoneal injections of amphetamine and methylphenidate (ritalin) at relatively low and high doses, the anti-psychotic drugs chlorpromazine and haloperidol and combinations of haloperidol with methylphenidate and amphetamine on the urinary excretion levels of unconjugated meta and para tyramine in the rat have been investigated. With the exception of a high dose of methylphenidate, none of the drug treatments changed significantly the urinary excretion level of para tyramine. meta Tyramine was significantly reduced by a low dose of amphetamine and a high dose of methylphenidate but significantly increased by a high dose of amphetamine. Such effects are different from those reported by Juorio (1977a, b) and Danielson, et al (1976) with respect to the rat striatum and mesolimbic systems where para tyramine was decreased and meta tyramine increased. The effect of adding anti-psychotic drugs in these latter studies was to potentiate their differential effects. Such differences indicate perhaps variations in the metabolism of the tyramines in peripheral tissues as compared with certain brain regions.

Animals↗

PubMed1979

Methodological problems in the analysis of behavioral tolerance in toxicology.

The analysis of selected data on differential behavioral tolerance to drugs and other chemicals leads to a series of tentative methodological proposals with potential interest for the purposes of toxicology. These data show a wide range of different relations between tolerance induced by continued exposure to treatment per se and tolerance dependent on specific treatment-behavior interactions, such as behavioral testing in the treatment state and unfavorable consequences on reinforcement density of response changes induced by treatment. Consequently, when tolerance phenomena occurring with a particular type of treatment deserve an in-depth analysis, a sequential strategy should assess (i) critical factors in short-term compensation for behavioral deficits (acute behaviorally augmented tolerance), (ii) relations between sensitization and tolerance phenomena (particularly in the case of agents with long-lasting and/or cumulative physiological-biochemical effects), with special regard to tolerance development in the absence of measurable changes in the lower dosage ranges, and (iii) factors responsible for behaviorally augmented tolerance in medium-and long-term experiments. The latter analysis may require the investigation of different relations between time of treatment and time of testing, and different treatment-induced changes in reinforcement density. Specific and non-specific transfer of coping responses across situations must also be considered, as well as changes in response topographies, interindividual differences in rate of tolerance development as a function of size and direction of the original treatment changes, and several other cues which can facilitate the understanding of the phenomena observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗