ABSTRACT
Abstract Introduction Perinatal hypothyroidism has a negative repercussion on the development and maturation of auditory system function. However, its long-term effect on auditory function remains unsettled. Objective To evaluate the effect of prenatal hypothyroidism on the auditory function of adult offspring in rats. Methods Pregnant Wistar rats were given the antithyroid drug methimazole (0.02%-1-methylimidazole-2-thiol- MMI) in drinking water, ad libitum, from gestational day (GD) 9 to postnatal day 15 (PND15). Anesthetized offspring from MMI-treated dams (OMTD) and control rats were evaluated by tympanometry, distortion product otoacoustic emission (DPOAE), and auditory brainstem response (ABR) at PNDs 30, 60, 90, and 120. Results Our data demonstrated no middle ear dysfunction, with the OMTD compliance lower than that of the control group. The DPOAE revealed the absence of outer hair cells function, and the ABR showed normal integrity of neural auditory pathways up to brainstem level in the central nervous system. Furthermore, in the OMTD group, hearing loss was characterized by a higher electrophysiological threshold. Conclusion Our data suggest that perinatal hypothyroidism leads to irreversible damage to cochlear function in offspring.
ABSTRACT
Introduction Perinatal hypothyroidism has a negative repercussion on the development and maturation of auditory system function. However, its long-term effect on auditory function remains unsettled. Objective To evaluate the effect of prenatal hypothyroidism on the auditory function of adult offspring in rats. Methods Pregnant Wistar rats were given the antithyroid drug methimazole (0.02% -1-methylimidazole-2-thiol- MMI) in drinking water, ad libitum, from gestational day (GD) 9 to postnatal day 15 (PND15). Anesthetized offspring from MMI-treated dams (OMTD) and control rats were evaluated by tympanometry, distortion product otoacoustic emission (DPOAE), and auditory brainstem response (ABR) at PNDs 30, 60, 90, and 120. Results Our data demonstrated no middle ear dysfunction, with the OMTD compliance lower than that of the control group. The DPOAE revealed the absence of outer hair cells function, and the ABR showed normal integrity of neural auditory pathways up to brainstem level in the central nervous system. Furthermore, in the OMTD group, hearing loss was characterized by a higher electrophysiological threshold. Conclusion Our data suggest that perinatal hypothyroidism leads to irreversible damage to cochlear function in offspring.
ABSTRACT
There are a range of products available which claim to accelerate the healing of burns; these include topical agents, interactive dressings and biomembranes. The aim of this study was to assess the effect of a gelatin-based membrane containing usnic acid/liposomes on the healing of burns in comparison to silver sulfadiazine ointment and duoDerme® dressing, as well as examining its quantification by high performance liquid chromatography. The quantification of the usnic acid/liposomes was examined using high performance liquid chromatography (HPLC) by performing separate in vitro studies of the efficiency of the biomembranes in terms of encapsulation, drug release and transdermal absorption. Then, second-degree 5cm2 burn wounds were created on the dorsum of nine male pigs, assigned into three groups (n=3): SDZ - animals treated with silver sulfadiazine ointment; GDU - animals treated with duoDerme®; UAL - animals treated with a gelatin-based membrane containing usnic acid/liposomes. These groups were treated for 8, 18 and 30days. In the average rate of contraction, there was no difference among the groups (p>0.05). The results of the quantification showed that biomembranes containing usnic acid/liposomes were controlled released systems capable of transdermal absorption by skin layers. A macroscopic assay did not observe any clinical signs of secondary infections. Microscopy after 8days showed hydropic degeneration of the epithelium, with intense neutrophilic infiltration in all three groups. At 18days, although epidermal neo-formation was only partial in all three groups, it was most incipient in the SDZ group. Granulation tissue was more exuberant and cellularized in the UAL and GDU groups. At 30days, observed restricted granulation tissue in the region below the epithelium in the GDU and UAL groups was observed. In the analysis of collagen though picrosirius, the UAL group showed greater collagen density. Therefore, the UAL group displayed development and maturation of granulation tissue and scar repair that was comparable to that produced by duoDerme®, and better than that produced by treatment with sulfadiazine silver ointment In addition, the UAL group showed increased collagen deposition compared to the other two groups.
