Tensile properties of human tendo Achillis: effect of donor age and strain rate

Two sets of tensile tests were conducted on tendo Achillis taken from 16 embalmed cadavers (donor ages, 36 to 100 years). From the stress, sigma-versus-strain, epsilon results, values of the following properties were obtained: linear stiffness, ST (which is defined as the slope of the linear zone of the post-toe region of the load-versus-extension plot), ultimate tensile strength [UTS], the strain at the UTS point (herein called the ultimate tensile strain) [epsilon max], and the tangent modulus of elasticity, [ET] (which is the slope of the linear zone of the post-toe region of the sigma-epsilon curve). In the first set of tests, the loading rate was 10%/sec. The results are thus: linear stiffness: 685 +/- 262 N/mm.; UTS = 59 +/- 18 MPa; epsilon max = 22 +/- 7%; and ET = 375 +/- 102 MPa. It was found that donor age exerts an insignificant effect on linear stiffness, a marked effect on UTS, an insignificant effect on epsilon max, and a moderate effect on ET (Student's t-test; p < 0.05). In the second set of tests, the test tendons were taken from the cadavers of "middle-aged" donors (52 to 67 years), and the strain rate was 100%/sec. By combining the results of the first and second sets of tests for a subset of this group (i.e., those with matched counterparts), it was found that strain rate has a statistically significant effect on ST and ET but not on UTS and epsilon max (paired Student's t-test; p < 0.05). Based on all results and findings, donor age is suggested as one of the considerations when selecting tendo Achillis to be used as allografts for the repair of severely damaged or ruptured tendo Achillis or anterior cruciate ligament.     

Dose-related vestibular and cochlear effects of transtympanic gentamicin

Perianal Paget's disease is rare, and its relationship to an associated internal regional cancer has been ill defined. We analyzed the histologic and immunohistochemical features of perianal Paget's disease in 11 patients to determine the frequency and relationship of associated regional internal carcinoma and to gain insight into its histogenesis. Of five patients with documented rectal adenocarcinoma, it was discovered synchronously with the Paget's disease in four and, subsequently, in one. Paget's cells of signet ring type predominated in four cases. Intraepithelial glands with intraluminal dirty necrosis were present in four cases. The immunophenotype in four cases studied was cytokeratin (CK)7+/CK20+/gross cystic disease fluid protein- (GCDFP) in both the intraepithelial Paget's cells and the invasive rectal adenocarcinoma. Six patients did not have documented rectal carcinoma. The Paget's cells in four were CK7+/CK20-/GCDFP15+. Three of these had purely intraepithelial Paget's disease, and invasive or metastatic disease developed in none after wide local excision. Bilateral inguinal lymph node metastases developed in the fourth patient, and the patient died 8 months after diagnosis of Paget's disease. In two patients, the Paget's cells were CK7+/CK20+/GCDFP15-. Recurrent intraepithelial perianal Paget's disease developed in one patient at 7 months; the patient was alive without disease at 24 months, and the other patient had several intraepithelial recurrences of perianal Paget's disease, and, subsequently, a large perianal tumor of uncertain cell type developed at 108 months, which led to the patient's death. We conclude that there are two types of perianal Paget's disease. One type has endodermal differentiation with gastrointestinal-type glands containing intraluminal dirty necrosis, numerous signet ring cells, CK20 positivity, and GCDFP15 negativity. Such cases are especially likely to be associated with synchronous or metachronous rectal adenocarcinoma. The other type is a primary cutaneous intraepithelial neoplasm in which the Paget's cells display sweat gland differentiation, including GCDFP15 positivity; it generally lacks gastrointestinal-type glands, intraluminal dirty necrosis, and CK20 positivity. The CK7 is a sensitive, albeit nonspecific, marker for Paget's cells.     

The effects of rigidity of internal fixation plates on long bone remodeling. A biomechanical and quantitative histological study

The effect of rigidity of internal fixation plates on long bone remodeling was studied using two types of plates with considerable differences in stiffness. The plated bones were subjected to bioengineering quantitative histological, and cortical thickness studies after 9 and 12 months. The biomechanical results, together with the quantitative histological measurements of the macroscopic architecture, showed that tissue characteristics of the plated bones were similar. However, because of the larger cortical area, the less regidly plated femora can sustain significantly higher loads and energy before failure. Cortical thickness measurements also showed that rigid plate immobilization results in thinning of the cortex of the underlying bone. The experimental results suggest that cortical bone remodels according to functional stress demands, and the osteoporosis secondary to rigid plate protection is consequent to thinking of its cortex.     

Artificial trabeculum (MESH). Clinical and histological study in the rabbit

PURPOSE: Designed to avoid postoperative hypotony that often occurs after trabeculectomy and to maintain long lasting filtration, the MESH is a thin porous expended polytetrafluoroethylene (ePTFE) implant that mimics the physiological meshwork. The aim of this study is to assess the tolerance, biocompatibility and effectiveness of this device during 6 months in the rabbit. MATERIAL AND METHODS: We used an ePTFE with about 5 microns pore size (Zytex). The head of the implant is 3,0 mm wide and 1,5 mm long and fits in the anterior chamber. The tail is 2,0 mm wide and 3,0 mm long and fits in the subconjunctival space. The MESH is 250 microns thick. 24 Dutch pigmented rabbits were selected because their dark pigmented iris contrasts with the ePTFE implant giving a better visualization. All the animals were cared for in accordance with ARVO resolutions. Surgery was performed on the right eye by the same surgeon (P.H.), the left eye serving as control for IOP measurements. The animals were distributed in 3 groups: one with MESH alone (MESH), one with MESH and Mitomycin C (MMC), one with MESH and 5-FU (5-FU). Follow-up was performed every week (W) during 6 months including IOP measurement, slit lamp observation, photography and bleb assessment. Histological study was done at POD 0, 15, 30, 90 and 180 one eye in each group. Student t test and alternate Welch t test were used for statistics. RESULTS: Filtering bleb: no bleb was visible before W3. A bleb was found between W3 and W6, decreasing between W6 and W9 with no more change after W10. The MESH implant: no change appears in the color of the MESH during the study. Some iris pigments or synechiae were seen in some cases. No extrusion occurred. Intraocular pressure: IOP was lower than in the control eye. The statistical analysis showed a significant lower pressure for the MESH alone at W5 (p = 0.0069), for the 5-FU group at W1 (p = 0.0326), W2 (p = 0.0488), W4 (p = 0.0312). With Mitomycine C we found very significant results at W1 (p = 0.0073), W2 (p = 0.0136), W4 (p = 0.0497), W9 and W11 (p = 0.0174). After W12 the groups were joined and IOP was significantly decreased at W17 (p = 0.0376) and W23 (p = 0.0462). Histology confirmed the correct position of the MESH, its biocompatibility and its ability to drain aqueous humor even if there is colonization of the pores by fibroblast-like cells. CONCLUSION: The present study has shown that the filtering bleb appeared after 3 weeks without major hypotony. The material was integrated only in the intrascleral tunnel and was stable. After 6 months the Mesh was well tolerated. The new concept has a simple surgical technique, less invasive than trabeculectomy and required less surgical time. This technique reduced IOP and produced long survival blebs in rabbits. This device appears suitable for the surgical treatment of open angle glaucoma.     

An electrophysiological and histological study on the neurotoxicity of lidocaine in excised rabbit cervical vagus nerve

We studied the neurotoxic effect of lidocaine at different concentrations on the desheathed rabbit vagus nerve by measuring the amplitudes of evoked compound action potentials and the histological changes of the nerve by means of the electron microscopy after incubation in lidocaine-Ringer's bicarbonate (RB) solution. The following results were obtained. 1) Minimum concentrations of lidocaine for producing complete conduction block (minimum blocking concentration, MBC) were 0.02% for A beta and A delta fibers, and 0.03% for C fibers. 2) Irreversible conduction blocks of compound action potentials were observed in relation with lidocaine concentrations and the duration of incubation: e.g. 0.5% for 2 hours incubation was equivalent to the block with 1% for 1 hour. 3) Degenerative change of axons was revealed morphologically in the preparations exposed to 2% or a higher concentration of lidocaine. 4) Risk ratio, which means a numerical value calculated as clinical concentration/irreversible concentration with 2 hr exposure, was similar to other local anesthetics except dibucaine HCl, which shows an higher risk ratio. However, it should be noted that lidocaine has an risk of producing irreversible changes in nerve fibers, when applied to the nervous tissue at higher concentrations for longer durations.     

Neuroprotective effects of lamotrigine in global ischemia in gerbils. A histological, in vivo microdialysis and behavioral study

A sudden surge in the release of glutamate is currently believed to be an important initiating step in neuronal damage due to an ischemic insult. In this experiment, we tested the efficacy of neuroprotection with lamotrigine, a novel antiepileptic drug that blocks voltage gated sodium channels and inhibits the ischemia-induced release of glutamate in the gerbil forebrain model of cerebral ischemia. The medication was administered 30 min before and 30 min after the insult in two groups of animals. Histological assessment of neuronal damage was evaluated at 7 and 28 days after the ischemic insult. Animals evaluated at 28 days also underwent behavioral testing. Microdialysis was used in the same model to study the response of ischemia-induced glutamate in saline treated controls versus animals treated with lamotrigine 20 min before the insult. There was highly significant neuronal protection in animals who were treated with lamotrigine either before or after the insult. Protection was seen both at 7 and 28 days after the insult. Behavioral testing also showed significantly better recovery in both sets of animals in comparison to the saline-treated group. Microdialysis confirmed a significant attenuation of the ischemia-induced glutamate surge when compared to the saline-treated animals. Our morphological, behavioral and microdialysis experiments show that lamotrigine offers significant neuroprotection from the effects of transient forebrain ischemia in gerbils. Neuroprotection with post-ischemic therapy probably depends on preserving the capacity of the sodium/calcium exchanger to reduce intracellular calcium concentrations or persistent 'toxicity' of glutamate in the reperfusion period on the already 'primed' injured neurons. These concepts need further study.     

A histological and immunohistological study of malarial placentas

Sections of 18 malaria-infected placentas were stained with haematoxylin and eosin, periodic acid and methenamine silver, and immunohistochemically with monoclonal antibodies against human common leukocyte antigen, CLA (CD 45), B cells (CD 20, L 26), T cells (CD 45RO, UCHL-1) and collagen IV. Parasitized erythrocytes accumulated in the maternal villous spaces, with none in the foetal circulation. These were found in association with inflammatory leukocytes and pigments. Fibrinoid necrosis was more prevalent in the heavily infected placentas. Thickening and reduplication of foetal capillary basement membranes, and a decrease in leukocytes, including B and T cells, were seen in the heavily infected placentas. These findings are in keeping with previously reported depression of cellular and humoral immunity in patients with heavy parasitaemia.     

Local calcergy. A histological, histochemical and electronprobe X-ray analytical study

The early stages of local calcergy in the mouse are characterized by a close focal relationship between injected lead (Pb), calcium (Ca) and phosphorus (P) and this association occurs before the latter 2 ions are detectable by conventional histochemical techniques.     

Effect of surgical technique on meniscus transplants. A histological, animal experiment study

Heparan sulphate binding to cells of the gastric pathogen Helicobacter pylori at pH 4-6 is common. Binding was inhibited by various unlabelled sulphated polysaccharides and at high ionic strength and pH, but not by carboxylated or non-sulphated compounds. The inhibition by various sulphated compounds such as dextran sulphate and carrageenans was related to the sulphate content and not to the carbohydrate polymer backbone. The IC50 values for heparin and dextran sulphate for H. pylori strain 25 were calculated as 3.55 x 10(-7) M and 5.01 x 10(-6) M respectively. Heparin-binding proteins of H. pylori are exposed on the cell surface, as shown by biotinylation of cell-surface proteins before separation of outer membranes and by an indirect immunofluorescence assay. The strongest biotin-heparin binding by H. pylori was observed with a polypeptide in the 55-60 kDa region.     

Barraquer-silk (8 x 0) and polyglactin 910 (8 x 0) in corneo-scleral incisions of rabbit eyes. A histological study

Barraquer-silk (8 x 0) and Polyglactin 910 (8 x 0) were histologically examined in corneo-scleral incisions of rabbit eyes. Wound healing using both suture materials was complete after two weeks, as observed by light microscopy. Barraquer-silk excited more cellular reaction than Polyglactin 910. Absorption of Polyglactin 910 suture began 18 days after surgery whilst Barraquer-silk did not begin to absorb until 42 days had passed.     

Dose-related cardiovascular effects of amrinone and epinephrine in reversing bupivacaine-induced cardiovascular depression

Effective dose, an indicator of the stochastic effect of radiation, has been widely used in dose evaluation in the environment. Though conversion factors have been used to obtain E from the air kerma or air absorbed dose, the variation of the conversion factors due to the change of exposure conditions has not been sufficiently investigated. This report documents an investigation of the variation of the effective dose per air kerma for environmental gamma rays depending on the exposure conditions using anthropomorphic phantoms and Monte Carlo calculations, taking into account the precise angular and energy distributions of the environmental gamma rays incident on the human body. As causes of the variation, posture of human bodies, biases of environmental source distributions, and body size were considered. The variation of effective dose in a prone position compared with that in a standing position was found to be within 30%. The bias of environmental sources causes the effective dose per air kerma to vary by 20% at maximum, but in some cases for low-energy gamma rays the variation was found to be up to 40% due to the change in the energy spectrum. The effective dose for a new born infant was estimated to be higher than that for an adult by a maximum of 80-90% for low-energy gamma rays from anthropogenic sources because of a lower shielding effect of the smaller body. The variation of the effective dose equivalent shows a similar tendency to the effective dose. Consequently, this study made it possible to estimate the uncertainties of effective dose and effective dose equivalent evaluated from air kerma or absorbed dose in air using the standard available conversion factors.     

Abdominal wall prostheses. Biomechanic and histological study

The best prosthetic material is one which provides the best mechanical resistance with the best biological tolerance. In order to assess the mechanical and histological properties of abdominal wall prostheses, we performed experimental tests in animal models comparing four materials: polypropylene, dacron, polyglactine 910 and a dacron-polyglactine 910 composite. One hundred thirty rabbits were used including 10 controls and 120 test animals. A medial laparotomy was closed with an antemuscular aponevrotic prosthesis in the test animals. Animals were sacrificed at one, two and three months after the operation. Abdominal wall and prosthesis samples were tested to determine resistance to pressure and extension, deformability and elasticity. Histology tests were also done to determine resistance quality and biological tolerance. Dacron was tolerated best and was less resistant than polypropylene, though resistance was satisfactory. There was no advantage with polyglactine compared with non-resorbable prostheses; its only indication would be a septic site. The composite material tested had a resistance comparable with that of dacron but was less well tolerated.     

Retrograde effects of electroconvulsive shock on learned responses.

Indicates that electroconvulsive shock (ECS) has 3 different effects on responses learned prior to its administration. 1st, the aversive effect of ECS, demonstrable in 1 trial but usually found after repeated presentations, can produce a delay-of-punishment gradient. 2nd, ECS apparently differentially affects memory depending upon the learning-ECS interval, an effect which can be interpreted as disruption of memory consolidation. The postlearning interval during which ECS produces temporally graded memory effects is very brief, probably well under 1 min. The 3rd effect of ECS is the halting of the incubation, i.e., the development over time, of a punishment-produced conditioned emotional response. In the passive avoidance learning situation, incubation disruption and memory disruption have identical behavioral consequences in that in both cases Ss tend to repeat the previously punished response. The postpunishment time course of incubation is relatively long, with maximum response suppression occurring between 1 and 4 hr. after punishment. The ECS disruption of the long-term incubation process has frequently been misinterpreted as ECS disruption of a long-term memory consolidation process. (60 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A histological and immunohistochemical study of medical-grade fluid silicone

BACKGROUND: Growth cone-associated protein (GAP43) is found in growing axons and we hypothesized that systemic treatment with antineoplastic agents should disrupt regeneration of olfactory receptor cells. Disruption of regeneration should be evidenced by decreased presence of growing axons in the olfactory bulb. OBJECTIVE: To evaluate GAP43 in human olfactory bulb in normal controls and in individuals receiving treatment for neoplasms. DESIGN: Immunocytochemical studies were performed on autopsied human olfactory bulbs to identify both GAP43 and olfactory marker protein immunoreactivity. The former recognizes growing axons and the latter is a definitive marker of adult olfactory nerve. SUBJECTS: Twenty-seven subjects were evaluated. Seven had received either antineoplastic agents and/or x-irradiation of the whole head. Four subjects were young, untreated controls, 10 were age matched to the treated group, and 2 had neoplasms but did not receive antineoplastic agents or irradiation of the head. In addition, 3 subjects with end-stage renal disease were immunostained. RESULTS: Subjects treated with antineoplastic agents or x-irradiation of the whole head displayed no statistically significant loss of olfactory bulb glomeruli, but GAP43 immunoreactivity was markedly reduced in all but 1 subject (P<.32). The subjects with end-stage kidney disease showed frank loss of both GAP43 immunoreactivity and olfactory glomeruli. CONCLUSIONS: Treatment with antineoplastic agents apparently does not damage olfactory epithelium directly but inhibits growth of new axons into the olfactory bulb. This observation suggests that the quality of olfactory experience may change during the course of treatment with antineoplastic agents because the olfactory nerve is not replaced.