Cysts in human thymus: maturational forms of Hassal's corpuscles?

Presence of extracellular cystic cavities in the thymus of many vertebrates has long been known. Various forms of such structures in human thymus were observed and examined thoroughly on immunostained and serial semithin sections. We grouped these structures into five categories according to their most characteristic features. The lympho-epithelial content of the cysts clearly reflected the structural features and antigenic profile of thymic cortical parenchyma in both elongated and ovo-spherical cysts. Our findings suggest that the various types of cystic structures observed in human thymus may represent maturational stages of classical Hassal's corpuscles. Presence of cortical lympho-epithelial content and its gradual replacement with debris material also suggests a unique mechanism of thymocyte disposal.

Sulbactam-cefoperazone polyhydroxybutyrate-co-hydroxyvalerate (PHBV) local antibiotic delivery system: in vivo effectiveness and biocompatibility in the treatment of implant-related experimental osteomyelitis.

In this study, a novel antibiotic carrier system for use in the treatment of implant-related and chronic osteomyelitis was developed. Sulbactam-cefoperazone was introduced to rods of polyhydroxybutyrate-co-hydroxyvalerate (22 mol % HV, w/w), a member of a family of microbial-origin polymer that is biodegradable, biocompatible, and osteoconductive due to its piezoelectric property. The antibiotic-loaded carrier was implanted into the infection site that was induced by Staphylococcus aureus inoculation into the rabbit tibia. The effectiveness of this was assessed macroscopically, radiographically, bacteriologically, and histopathologically. Findings of infection subsided on day 15 and almost complete remission was observed on day 30. The control side that contained antibiotic-free rods, however, worsened. These findings prompted us to conclude that the novel biodegradable antibiotic carrier developed in the present study seems to be a promising candidate for use in the treatment of severe bone infection.

Development of a calcium phosphate-gelatin composite as a bone substitute and its use in drug release.

This study was carried out to develop a calcium phosphate-gelatin composite implant that would mimic the structure and function of bone for use in filling voids or gaps and to release bioactive compounds like drugs, growth hormones into the implant site to assist healing. XDS analysis of the synthesized calcium phosphate revealed a calcium to phosphorus molar ratio of ca. 2.30, implying a less erodible material than hydroxyapatite (1.67). Release of the antibiotic gentamicin from the implant was with a burst, whether in situ or in vivo, followed by an almost constant release for about three months. It was found that the release rate could be decreased by increasing the density of the gelatin membrane. Upon implantation into rabbit tibia the release duration was substantially shortened (to about 4 weeks) with respect to the in situ tests basically due to the degradation of gelatin. In vivo studies with rabbits confirmed this degradation. The composite was perfectly biocompatible as shown by the histological studies. It, thus, has a great potential as a bone substitute material.

A study of adenosine treatment in experimental acute spinal cord injury. Effect on arachidonic acid metabolites.

STUDY DESIGN: A prospective, randomized, blinded experimental trauma study. STUDY OBJECTIVE: The effect of adenosine on arachidonic acid metabolites and lipid peroxidation was investigated in induced spinal cord injury. SUMMARY OF BACKGROUND DATA: Effects of adenosine in ischemia-reperfusion models have been studied, but no studies of adenosine's effect on direct trauma to the spinal cord have been reported. METHODS: Thirty-seven adult Wistar albino rats were randomly divided into four groups and underwent laminectomy. Group 1 underwent a sham operation. Group 2 received an intravenous adenosine infusion of 100 micrograms/kg per minute for 30 minutes. In Group 3, a standard spinal cord trauma of 50 g.cm strength was established at the lower thoracic level with a "weight-drop" technique, and Group 4 received an infusion of adenosine (100 micrograms/kg per minute) for 30 minutes after the trauma. RESULTS: Tissue prostaglandin E2 activity was significantly higher in adenosine-treated trauma groups when compared with that in other groups (P < 0.0001). The difference in tissue leukotriene C4 activity between control and trauma groups was significant (P < 0.05). Adenosine infusion after trauma limited the increases in lipid peroxidation, with the difference approaching significance at P = 0.06. The structure of myelin was well preserved in the adenosine-treated trauma group. However, the changes were irreversible in severely damaged areas. CONCLUSION: After acute spinal cord trauma, intravenous adenosine infusion of 100 micrograms/kg per minute could attenuate progression to secondary injury, but adenosine alone was not effective yet.

Endoglin (CD 105) expression in human lymphoid organs and placenta.

Endoglin (CD 105) is a cell surface antigen widely expressed on vascular endothelium, syncytiotrophoblast, some tissue macrophages, certain culture cells (including early leukemic B-lineage) and some endothelial cell lines. Though its relation to the transforming growth factor-beta (TGF-beta) receptor system is well documented, its function and detailed pattern of expression still remain to be clarified. We examined the differential tissue distribution of endoglin in human lymphoid organs and placenta with several anti-CD 105 monoclonal antibodies (mAbs) using an indirect immunoperoxidase technique, and performed semi-quantitative measurements using an image-analyzing system for comparison. Arterial, venous and capillary endothelia in these organs were reactive with anti-CD 105 mAbs at varying intensities. Interestingly, a distinctly stronger staining pattern was observed in the high endothelial venules (HEVs) which may indicate a special role for endoglin in lymphocyte trafficking. Syncytiotrophoblast expressed endoglin strongly on their apical cell membrane. Extravillous trophoblasts at certain locations selectively expressed endoglin on their cell membranes, suggesting a special role for this surface antigen during trophoblast differentiation.

Effects of octreotide and a-tocopherol on bacterial translocation in experimental intestinal obstruction: a microbiological, light and electronmicroscopical study.

BACKGROUND/AIMS: Bacterial translocation induced by intestinal obstruction is suggested to be due to increased intestinal luminal volume, leading to intestinal overgrowth with certain enteric microorganisms and intestinal mucosal damage. If this suggestion is true, maintenance of intestinal mucosal integrity by a cytoprotective agent, a-tocopherol, and inhibition of gastrointestinal secretions by octreotide should decrease the incidence of bacterial translocation and extent of mucosal injury due to intestinal obstruction. METHODS: Complete intestinal obstruction was created in the distal ileum of male Wistar Albino rats by a single 3-0 silk suture. The animals received subcutaneous injections of 1 ml of physiologic saline (group 1) (PS 24) and 1 ml of saline containing octreotide acetate (100 micrograms/kg) (group 2) (OC 24), at 0, 12 and 24 hours of obstruction. In group 3 (PS 48) and group 4 (OC 48), the rats were treated with subcutaneous physiologic saline (1 ml) and octreotide acetate (100 micrograms/kg), respectively, beginning at the time of obstruction and every 12 hours for 48 hours. The rats in group 5 (Toc 24), were pretreated with intramuscular a-tocopherol 500 mg/kg on day 1 and 8, and underwent laparotomy on day 9. A third dose of a-tocopherol was injected at the time of obstruction on day 9 and no treatment was given thereafter. We tested the incidence of bacterial translocation in systemic organs and circulation and evaluated the histopathological changes in all groups. RESULTS: Treatment with octreotide acetate was found to be ineffective in reducing the incidence of translocation, with no histopathological improvement. Mucosal damage scores, on the other hand, in the a-tocopherol group were statistically less than those in the octreotide and control groups (p < 0.05). Additionally, a-tocopherol treatment decreased the incidence of organ invasion with translocating bacteria, although this difference did not reach statistical significance. CONCLUSION: Octreotide acetate treatment in complete intestinal obstruction has no effect on the incidence of bacterial translocation. a-Tocopherol, on the other hand, has a cytoprotective effect on intestinal mucosa in intestinal obstruction which, in turn, is thought to decrease bacterial translocation when used in physiological doses and prophylactically.

Morphological changes in the myenteric plexus of rat ileum after transection and end-to-end anastomosis.

Surgical interruption of the gastrointestinal tract is widely used for investigating the structure of the enteric nervous system and in the treatment of certain pathological conditions of the gastrointestinal tract. The effects of transection and end-to-end anastomosis and myotomy on nerve cells of the myenteric plexus were studied by light and electron microscopy, 1, 2 and 6 wk postsurgically. During the 1st wk, degeneration of some nerve cells was indicated by the dilation of the endoplasmic reticulum and dispersion of Nissl substance. The degenerative process (an early electron-dense lamellar degeneration and a late floccular degeneration) was accompanied by some regenerative changes during the recovery period. Quantitative light microscopic analysis demonstrated a significant decrease in the number of neurons located 1 and 5 mm from operation sites in the intestine.

New applications for the zinc iodide-osmium tetroxide technique.

The zinc iodide-osmium tetroxide (ZIO) fixation/staining method was applied for neurocytological studies and also to examine several other tissue samples including epidermal Langerhans cells, blood and bone marrow cells and lymphoid tissue. Although precise specificity cannot be attributed to the staining reaction, interesting staining patterns for different cell types were observed by using one of the ZIO staining solutions. The significance of ZIO positivity is briefly discussed.

Ultrastructural changes in the mucosa of the small intestine in patients with geophagia (Prasad's syndrome).

The ultrastructure of intestinal mucosa in two geophagia patients with growth retardation, hypogonadism, hepatosplenomegaly, zinc deficiency, iron deficiency, and anemia was studied with an electron microscope. Alterations in the ultrastructure of intestinal mucosa, especially in Paneth's cells, possibly due to zinc deficiency were observed.