Contact urticaria to formaldehyde

A patient developed urticaria following exposure to formaldehyde vapour. Evidence is given that this compound releases histamine from the skin of susceptible persons. The action mechanism seems to be different from IgE-mediated hypersensitivity, as the passive transfer test was negative.     

Immunorecognition of anti-serotonin antibodies by using a radiolabelled ligand

Specificity of anti-serotonin antibodies to be assayed for immunocytochemical studies was tested in vitro by using a radiolabelled ligand mimicking the hapten structure. A good immunorecognition was found after coupling [3H]HT to a lysine with formaldehyde. Competition experiments by equilibrium dialysis were then carried out between [3H]HT-F-ALM and both conjugated and unconjugated indoles. The cross-reactivity ratios showed that the antibody recognition, though less specific than expected, was found suitable for immunocytochemical applications.     

Acute low-level formaldehyde behavioural and neurochemical toxicity in the rat

1. The purpose of the present study was to determine the effects of low-level formaldehyde exposure upon behavior and neurochemistry in the male rat.

2. Rats were exposed to either air or formaldehyde vapor (5, 10 or 20 parts per million) for 3 hours on 2 consecutive days during which behavioral observations were made. Following the second exposure session the rats were sacrificed and their brains analyzed for norepinephrine, dopamine, 5-hydroxytryptamine and their major metabolites.

3. Formaldehyde exposure resulted in decreased motor activity and neurochemical changes in dopamine and 5-hydroxytryptamine neurons.     

Attenuation of formalin pain responses in the rat by adrenal medullary transplants in the spinal subarachnoid space

Previous reports have indicated that the implantation of adrenal medullary chromaffin cells into the spinal subarachnoid space can reduce both acute and chronic pain in several animal models. Recent findings suggest that acute and chronic pain alleviation may be mediated by distinct mechanisms. Since the formalin response is composed of an acute and tonic phase which can be pharmacologically distinguished, the ability of adrenal medullary implants to alter these responses was assessed. In rats with adrenal medullary transplants, both phases of the formalin response were attenuated, in contrast to control implanted animals. Suppression of the acute phase by adrenal medullary implants was reversed by the opiate antagonist naloxone, and partially reversed by the -adrenergic antagonist phentolamine, suggesting that opioid peptides and catecholamines released by the implanted chromaffin cells contribute to the observed antinociception. However, neither antagonist altered the antinociceptive effects of adrenal medullary implants on the tonic phase of the formalin response. These results indicate that adrenal medullary implants in the spinal subarachnoid space alleviate acute and tonic pain via distinct pharmacologic mechanisms.     

Anti-arthritic and disease modifying activity of Terminalia chebula Retz. in experimental models

Objective This study evaluates the anti‐arthritic effect of Terminalia chebula hydroalcoholic extract (TCHE) in experimental models and attempts to correlate the effect of treatment on macrophage‐derived pro‐inflammatory cytokine expression and extent of disease activity. Methods Arthritis was induced in rats by subplantar administration of either formaldehyde or complete Freund's adjuvant (CFA). Joint size was measured at regular intervals by using a micrometer screw gauge. Serum and ankle joints of rats immunized with CFA were collected and subjected to ELISA for estimation of TNF‐α level and immuno‐histochemistry for detection of IL‐1β, IL‐6 and TNF‐R1, respectively. An acute and 28‐day oral toxicity study was carried out to evaluate the safety of the test drug. Key findings TCHE produced a significant inhibition of joint swelling as compared with control in both formaldehyde‐induced and CFA‐induced arthritis. TCHE treatment also reduced serum TNF‐α level and synovial expression of TNF‐R1, IL‐6 and IL‐1β. Results of acute toxicity study showed that the oral LD50 of TCHE was >2000 mg/kg. Chronic administration also did not produce any significant physiological changes as compared with normal rats. Conclusion Results indicate that the anti‐arthritic activity of TCHE was at least in part due to its modulatory effect on pro‐inflammatory cytokine expression in the synovium. We believe that TCHE has the potential to be used as a disease‐modifying agent in treatment of rheumatoid arthritis.