Tehran University Medical Journal

Background: Tympanic membrane perforation as a sign of different otologic disorders have multiple causes, for example trauma .Traumatic perforations heal spontaneously in most cases but in large and stable perforation otolarngologist intervention is necessary . In the stable perforation of tympanic membrane , if there isn’t infection in the tympanic cavity , the paper patch or myringoplasty may be used. These procedures need remedy charge and time and may be with morbidity and other complications. Recently materials like hyaluronic acid and epidermal growth factors has been used to speed healing of tympanic membrane perforation, and their effect has been proved. Pentoxifylline an anti-thrombotic drug has positive effect on increasing perfusion and wound healing in pathological conditions. Alike we have used pentoxifylline to show it’s effect on the healing of guinea pig perforated tympanic membrane.

Materials and Methods: This study has been done prospectively, on 32 guinea pig ears.

  Results & Conclusion: Final otomicroscopic study after three weeks showing no significant difference in the healing rate of tympanic membrane in pentoxifylline group versus control group.

Background: Adenosine receptors play an important role in the treatment of paroxysmal supraventricular tachycardia in cardiovascular system. This effect is through interaction with A1 type of G-protein-coupled adenosine receptors. The effect of N6-cyclopentyladenosine (CPA), an A1-selective adenosine agonist, was studied on ouabain-induced toxicity in spontaneously beating isolated guinea pig atria.

Methods: In the beginning the isolated guinea pig atria were mounted on the organ bath containing modified krebs and contractile responses in the four groups (shame, CPA, ouabain, CPA- ouabain) were measured.

Results: CPA (2-16nM) produced a dose-dependent decrease in the force of contractions (34%-51%) and in the rate of contractions (22%-48%). CPA significantly increased the time of onset of arrhythmia (toxicity) induced by ouabain (1.2µM) when it was administered 10 min before ouabain was added in organ bath. Ouabain (1.2µM) alone produced arrhythmia at 7 min and either asystole or standstill at 22 min. CPA (8nM) increased the time required to produce arrhythmia to 27.5 min and prolonged beating atria to more than 63 min and prevented the occurrence of asystole.

Conclusion: CPA produces direct cardiac action, probably due the inhibition of cardiac Ca²⁺ channel and membrane hyperpolarization of atrium cells in guinea pig atria. Moreover, our results suggest that CPA may reduce the membrane conduction through inhibition of ionic channels, which decrease ouabain- induced toxicity.

Background: Nowadays skin damages caused by ultraviolet (U.V.) radiation from the sun were increased accordingly necessity for safe and inexpensive protective products for reducing the harmful effects of this ray is unassailable. The antiradical, anti irritation and anti-cancer properties of silymarin make it a suitable option for use in cream formulation to investigate its effect on skin disorders caused by U.V. radiation. In this research effect of local application of a cream containing silymarin in prevention of the harmful effects of U.V. radiation on the guinea pig skin were studied and evaluated by using histopathologic and clinical findings.

Methods: 75 albino guinea pigs were randomly divided into five groups of fifteens. 2cm2 of the back hair was shaven. In the first group no treatment was applied, in the second group vaseline, in group 3 base cream without silymarin extract, in group 4 silymarin extract and in group 5 cream containing silymarin extract were used.

Results: In clinical assessment, skin scaling, skin irregularity, erythema, skin hyperpigmentation, and edema were observed and in histopathological observation epidermal hyper keratosis, hyperpigmentation, exocytosis, acanthosis, chromatin discoloration in nucleus of epidermal squamous cells, perifolliculitis, dermal vascular hyperemia, edema and dermal thickness, infiltration of plasma cell lymphocytes and eosinophyls into dermis were detected. The statistical comparison of group 1 and group 5 shows statistically significant difference in most indices (p<0.01).

Conclusions: Clinical and histopathologic examinations showed that local application of a cream containing silymarin is effective in prevention of skin damage caused by U.V. radiation in guinea pig's skin also the results of the clinical and histopathologic observation in this study confirm the enzymatic results in other researches.