The morphology, biomechanics, and physiological function of the suboccipital myodural connections

The myodural bridge (MDB) connects the suboccipital musculature to the spinal dura mater (SDM) as it passed through the posterior atlanto-occipital and the atlanto-axial interspaces. Although the actual function of the MDB is not understood at this time, it has recently been proposed that head movement may assist in powering the movement of cerebrospinal fluid (CSF) via muscular tension transmitted to the SDM via the MDB. But there is little information about it. The present study utilized dogs as the experimental model to explore the MDB’s effects on the CSF pressure (CSFP) during stimulated contractions of the suboccipital muscles as well as during manipulated movements of the atlanto-occiptal and atlanto-axial joints. The morphology of MDB was investigated by gross anatomic dissection and by histological observation utilizing both light microscopy and scanning electron microscopy. Additionally biomechanical tensile strength tests were conducted. Functionally, the CSFP was analyzed during passive head movements and electrical stimulation of the suboccipital muscles, respectively. The MDB was observed passing through both the dorsal atlanto-occipital and the atlanto-axial interspaces of the canine and consisted of collagenous fibers. The tensile strength of the collagenous fibers passing through the dorsal atlanto-occipital and atlanto-axial interspaces were 0.16 ± 0.04 MPa and 0.82 ± 0.57 MPa, respectively. Passive head movement, including lateral flexion, rotation, as well as flexion–extension, all significantly increased CSFP. Furthermore, the CSFP was significantly raised from 12.41 ± 4.58 to 13.45 ± 5.16 mmHg when the obliques capitis inferior (OCI) muscles of the examined specimens were electrically stimulated. This stimulatory effect was completely eliminated by severing the myodural bridge attachments to the OCI muscle. Head movements appeared to be an important factor affecting CSF pressure, with the MDB of the suboccipital muscles playing a key role this process. The present study provides direct evidence to support the hypothesis that the MDB may be a previously unappreciated significant power source (pump) for CSF circulation.

A method of removing retardance induced by scattering of collagenous fiber bundles

In this work, we report a method of removing scattering induced retardance in polarization sensitive full field optical coherence tomography (PS-FFOCT). First, the Mueller matrix that describes its operation is derived. The thickness invariant retardance induced by the scattering of collagenous fiber bundles is then used to find the accurate values of the birefringence of the layers that consist collagenous fibers. Finally, the initial en face birefringent images of in vitro beef tendon samples are presented to demonstrate the capability of our method.

Quantitative and Qualitative Assessment of Adhesive Thrombo-Fibrotic Lead Encapsulations (TFLE) of Pacemaker and ICD Leads in Arrhythmia Patients—A Post Mortem Study

The demand for cardiac implantable electronic devices for arrhythmia therapy is still unabated and rising. Despite onward optimizations, lead-related problems such as infections or fractures often necessitate lead extraction. Due to adhesive thrombo-fibrotic lead encapsulations (TFLE) transvenous lead extraction is challenging and risky. However, knowledge on TFLEs and possible correlations with technical lead parameters and dwelling time (DT) were hitherto insufficiently studied. Therefore, we analyzed TFLEs of 62 lead from 35 body donor corpses to gain information for a potential lead design optimization. We examined both TFLE topography on the basis on anatomical landmarks and histo-morphological TFLE characteristics by means of histological paraffin sections and scanning electron microscopy of decellularized samples. The macroscopic analysis revealed that all leads were affected by TFLEs, mainly in the lead bearing veins. Half (47.2%) of the right-ventricular leads possessed adhesions to the tricuspid valve. On average, 49.9 ± 21.8% of the intravascular lead length was covered by TFLE of which 82.8 ± 16.2% were adhesive wall bindings (WB). The discrete TFLEs with at least one WB portion had a mean length of 95.0 ± 64.3 mm and a maximum of 200 mm. Neither sex, DT nor certain technical lead parameters showed distinct tendencies to promote or prevent TFLE. TFLE formation seems to start early in the first 1–2 weeks after implantation. The degree of fibrotization of the TFLE, starting with a thrombus, was reflected by the amount of compacted collagenous fibers and likewise largely independent from DT. TFLE thickness often reached several hundred micrometers. Calcifications were occasionally seen and appeared irregularly along the TFLE sheath. Leadless pacemaker systems have the advantage to overcome the problem with TFLEs but hold their own specific risks and limitations which are not fully known yet.

Experimental Acute Sepsis Reduced Number of Osteocalcin Immunolabeled Cells in Periodontal Ligament

The aim of this study was to evaluate the effect of acute sepsis in the periodontal ligament, alveolar and furcation bone in absence of periodontitis induction through histological and immunohistochemical analyses. A septic rat model was established by cecal ligation and puncture (CLP). Twelve rats were randomly divided into CLP (n=6) and Sham (n=6) groups. The animals were euthanized at 24 h and hemimandibles were submitted to histomorfometric (bone matrix, collagenous fibers, fibroblasts, osteocytes, inflammatory cells, and blood vessels) and immunohistochemical (BMP-2/4, RANKL and osteocalcin) evaluation in alveolar bone, furcation bone and periodontal ligament. Our results demonstrated that histomorphometric parameters were similar in alveolar bone, furcation bone and periodontal ligament of Sham and CLP rats. Regarding to immunohistochemical analyses, the number of BMP-2/4 and RANKL immunolabeled cells was also similar in both groups. Furthermore, it was detected a reduction in the osteocalcin immunolabeled cells in periodontal ligaments of CLP compared to Sham rats (p=0.0014). In conclusion, the acute sepsis induction resulted in reduced number of osteocalcin labelled cells in periodontal ligament region. Moreover, no significant histological differences were observed in the periodontium of rats under acute sepsis. Considering the role of osteocalcin in bone remodeling, the study contributes to revealing the importance of careful periodontal evaluation in the presence of sepsis.

RABBIT SEMINIFEROUS TUBULES

Objective: The aim of this article was to study the ultrastructure of the boundary tissue of rabbit seminiferous tubule. Design:Experimental study. Period: During July 2010 to July 2011. Material: Eight sexually mature male rabbits (Oryctolagus cuniculus) were used inthis study. Rabbit maturity was determined by age and semen samples. Method: Ultrastructure observations by electron microscopetransmission of normal rabbit testes. Setting: Samples processing were done in both university of Khartoum (Sudan) and then Assiut university(Egypt). Results: The boundary tissue is formed of three lamellae, inner fibrous, inner and outer cellular lamellae. The inner fibrous lamellaconsists of three strata; internal and external homogenous enclosing a middle stratum of collagenous fibers. The internal homogenous stratumof the inner fibrous lamella is subdivided into four layers of moderate electron density. Conclusions: The general structure of the seminiferoustubule of rabbit is similar to that of hamster and mouse, but the internal homogenous stratum is formed of four layers.

MORPHOLOGICAL EVALUATION OF INTENSITY OF DYSTROPHIC CHANGES IN ILIOLUMBAR, SACRO-ILIAC AND SACROTUBERAL LIGAMENTS: POTENTIAL FOR BIOPSY

Objective: to evaluate the potential of the use of a diagnostic puncture for the analysis of intensity of dystrophic changes in ilio-lumbar, sacro-iliac, and sacro-tuberal ligaments. Material and methods. The work presents the comparison of the results of the semi-quantitative morphological evaluation (Bonar scale) of the sectional material and the material obtained during biopsy of the iliac-lumbar, sacroiliac and sacro-ligamentous ligaments from 15 corpses (the average age at death was 64.5 ± 6.5). Results. The comparison of the sectional data and biopsy data detected differences in the evaluations of intensity of dystrophic changes in the part concerning the evaluation of fibroblasts that lead to a decreased final Bonar score by 1 point. Conclusion. Biopsy material can be used for approximate evaluation of intensity of dystrophic changes according to the criteria «interstitial substance», «collagenous fibers» and «vascularization». The evaluation according to the criterion «fibroblastic programed differentiation cells» can be decreased by 1 point, which should be taken in account in the data interpretation.

Is Autologous or Heterologous Pericardium Better for Valvuloplasty? A Comparative Study of Calcification Propensity

Pericardial calcification is detrimental to the long-term durability of valvuloplasty. However, whether calcification susceptibility differs between heterologous and autologous pericardium is unclear. In this study, we compared the progression of calcification in vivo between autologous and heterologous pericardium. We randomly divided 28 rabbits into 4 equal groups. Resected rabbit pericardium served as autologous pericardium, and commercial bovine pericardium served as heterologous pericardium. We subcutaneously embedded one of each pericardial patch in the abdominal walls of 21 of the rabbits. The 7 control rabbits (group A) received no implants. The embedded samples were removed at 2 months in group B, at 4 months in group C, and at 6 months in group D. Each collected sample was divided into 2 parts, one for calcium-content measurement by means of atomic-absorption spectroscopy, and one for morphologic and histopathologic examinations. When compared with the autologous pericardium, calcium levels in the heterologous pericardium were higher in groups B, C, and D (P <0.0001, P <0.0002, and P <0.0006, respectively). As embedding time increased, calcium levels in the heterologous pericardium increased faster than those in the autologous, especially in group D. Disorganized arrangements of collagenous fibers, marked calculus, and ossification were seen in the heterologous pericardium. Inflammatory cells—mainly lymphocytes and small numbers of macrophages—infiltrated the heterologous pericardium. The autologous pericardium showed a stronger ability to resist calcification. Our results indicate that autologous pericardium might be a relatively better choice for valvuloplasty.

Morphology of the male gonads of the spiny lobster Panulirus laevicauda (Latreille, 1817)

The present study represented a contribution to the knowledge of the cytological and histological aspects of decapods' reproductive system, describing male germ cells of the spiny lobster Panulirus laevicauda. Seventy-one specimens of different sizes were caught off Fortaleza (Ceará, Brazil). Their testes were removed and fixed in Bouin solution, then, after 24 hours, dehydrated, cleared and embedded in the paraffin. Sections (4 µm thick) were stained with hematoxylin-eosin. The testes appeared macroscopically as a pair of long and highly convoluted tubes joined by a transversal commissure giving the organ an H-like shape. Microscopically, supporting cells and germ cells (spermatogonia I and II, spermatocytes, spermatids and spermatozoa) were seen in the testicular acini. Some of the acini showed signs of the spermotocytes and the spermatogonia degeneration. The spermatozoa were small cells with the peripheral nuclei and a lightly basophilic cytoplasm. They were nonmotile gametes and are characterized by the absence of a flagellum, but they had spikes radiating from the body. Three stages of follicular development in the mature individuals were observed: (a) predominance of spermatogonia I and II; (b) increasing numbers of spermatocytes I and II; and (c) spermatocytes I and II were prevalent. All the three stages of the spermatozoa were observed in the follicular lumen. These observations agreed with the published descriptions of other palinurid and homarid lobsters. A histochemical analysis of the testes showed that the main component of the tunic was collagenous fibers, that the seminal fluid contained plenty of glycoproteins and carboxyl-glycoconjugates and that the spherical bodies and spermatozoa contained glycoproteins and mucoproteins.

Phenobarbital-induced Gingival Hyperplasia

Aim The aim of this article is to present a case of a phenobarbital-induced gingival hyperplasia (GH), discuss possible etiological mechanisms of drug-induced GH, and to present a concise review of the literature. Background GH is a well-known complication associated with anticonvulsant phenytoin, antihypertensive calcium channel blockers, and immunosuppressant cyclosporine therapy. Sodium valproate and primidone has very rarely been found to cause GH. Report An extremely rare case of phenobarbital-induced GH in a 28-year-old male patient who had received this drug for three years is presented. The histological examination of the lesion revealed a hyperplastic epithelium, epithelial acanthosis, and elongated rete ridges as well as obviously enhanced dense collagenous fibers and proliferation of fibroblasts. Summary Phenobarbital-induced GH is a rare clinical entity which necessitates meticulous evaluation. However, it seems to show a benign behavior with reference to recurrence after surgical excision. Citation Lafzi A, Farahani RMZ, Shoja MAM. Phenobarbital-induced Gingival Hyperplasia. J Contemp Dent Pract 2007 September; (8)6:050-056.