MYOFIBROBLASTS HINDER RECOVERY OF HASHIMOTO THYROIDITIS IN THE ULTRASTRUCTURAL LEVEL.

Background: Hashimoto thyroiditis (HT) is an autoimmune disorder associated with hypothyroidism. Lymphocyte infiltration leading to thyroid follicular cell destruction is counteracted by increased collagen production, deposition and scarring. However, only recently a specific subpopulation of modified fibroblasts with contractile properties, namely "myofibroblasts" (MFBs) have been linked to HT. Aim: Our ultrastructural study aims to delineate the presence and contribution of MFBs to the fibrotic milieu of HT. Material and Methods: Tissue biopsies were obtained from 5 HT-diagnosed patients and specimens were examined using a Transmission Electron Microscope (TEM). Results: Histopathological examination indicated extensive microvilli atrophy and atypical vacuolations of the thyroid follicular cells in the HT samples. In addition to interstitial extravasated lymphocytes, capillaries were encircled by MFBs (mean distance from lumen 1.248± 0.43µm) with the characteristic electron-dense α-smooth muscle actin (α-SMA), confirmable in higher magnifications. Myofibroblastic projections were found to have significantly higher representation near the capillary lumen compared to the impaired endothelial lining (P < 0.01). Conclusion: Our TEM findings suggest that the intrusion of endothelia by myofibroblastic projections can be a significant factor towards the malfunction of follicular cells in HT patients and offer a paradigmal understanding of the ultrastructural interactions that may underlie the HT pathology.

Functional recovery after experimental spinal cord compression and whole body vibration therapy requires a balanced revascularization of the injured site.

PURPOSE: Based on several positive effects of whole-body-vibration (WBV) therapy on recovery after SCI, we looked for correlations between functional (analysis of locomotion), electrophysiological (H-reflex) and morphological (density of functioning capillaries) measurements after SCI and WBV-treatment. METHODS: Severe compression SCI at low-thoracic level (T8) in adult female Wistar rats was followed by WBV twice a day (2 × WBV) over a 12-week post-injury period. Intact rats and rats with SCI but no WBV-therapy ("No-WBV") served as controls. Recovery of locomotion was determined by BBB-locomotor rating, foot stepping angle (FSA), rump-height index (RHI), correct ladder steps (CLS) and H-reflex at 1, 3, 6, 9, and 12 weeks after SCI. Animals were sacrificed by an overdose of Isoflurane (Abbott). One hour later their spinal cords were fixed in 4% PFA for 24 h. Samples from the thoracic cord containing the lesion site and from the lumbar intumescence were cut into 10 µm thick longitudinal frozen sections. RESULTS: All functioning capillaries were unequivocally identified because the endogenous peroxidase of the erythrocytes was clearly visualized with 0.05% diaminobenzidine (DAB). A determination of their absolute (in µm2) and proportional areas (percent of photographed tissue) revealed a significantly denser capillary network in the WBV-treated rats: 1,66 ± 0,41% in the "vibrated" rats versus 0,79 ± 0,19% in the "No-WBV" animals. The portion of the capillary network in intact rats was 1,51 ± 0,69%. Surprisingly, even though the vascularization in the treated animals was significantly increased, this had no beneficial influence on the recovery of functions after SCI. CONCLUSION: The results of this study provide for the first time evidence that intensive WBV-therapy leads to a significantly denser capillary network in the lesioned spinal cord. However, since this higher capillary density is not associated with improved functional recovery (possibly because it exceeded the balance necessary for functional improvements), optional treatments with lower intensity or less time of WBV-therapy should be tested.

Breast tumor developed in a pregnant rat after treatment with the teratogen Cycloheximide.

AIM: To describe histochemically and immunohistochemically a breast tumor presented in a pregnant rat given Cycloheximide to examine its teratogenic and embryotoxic effect on the embryos. METHODS: Cycloheximide was injected in pregnant Wistar rats at a dose of 3 mg/kg.b.w. on both 10th and 11th gestational days. In one of the rats, a large breast tumor developed rapidly. Histochemical staining with Hematoxylin-Eosin and Masson Trichrome and immunohistochemical identification with mouse monoclonal antibodies: a) Estrogen Receptor A and b) Estrogen Receptor B was performed. RESULTS: Analysis with A-receptor and B-receptor showed that the breast tumor which was developed after treatment with Cycloheximide was malignant. Positive immunohistochemical reaction was evident especially with A-receptor indicating the malignancy of the tumor. CONCLUSIONS: Cycloheximide is a known toxic and teratogenic agent and potentially a carcinogenic drug. Thus it should be used with extreme caution as a pesticide.