Weeks Of Fixation Research Articles

New data on brittle stars (Echinodermata: Ophiuroidea) from the Persian Gulf and Oman Sea, Iran

Brittle stars are one of the most diverse classes of echinoderms distributed worldwide in marine habitats. In this study, brittle stars were sampled by hand from the intertidal zone of the Persian Gulf's western part to the Oman Sea, from locations accessible without the need of a boat or diving equipment. Sampling time was set in the first days of the lunar month or at least the time of the lowest tide in each day. The specimens were first immobilized in freshwater, then fixed in neutralized buffered formalin, and finally preserved in 70% ethanol after one week of fixation. Of 22 sampling points, seven localities yielded intertidal brittle stars (Macrophiothrix hirsuta cheneyi, Macrophiothrix elongata, and Ophiocoma scolopendrina) during the sampling period (December 2017–March 2018). Ophiocoma scolopendrina is reported for the first time from Dayyer and Nayband in the Persian Gulf. We also re-evaluated recently reported data on ophiuroids from the studied area.

Structure of the Upper and Lower Surfaces of Human Corpus Callosum

The corpus callosum in the interval between the cerebral hemispheres is a plate of white matter, uneven in thickness, in which two surfaces are distinguished - the upper and lower ones, bent according to its lateral profile. The objective of the study was to study the individual variability of location of the lateral and medial longitudinal strips on the upper surface of the corpus callosum, as well as structural features of its lower surface. The material was the brain of men and women (10 specimens each) of the second period of adulthood, who died for the causes not related to the pathology of the central nervous system. After two weeks of fixation in a 10% formalin solution, the brain was prepared by separating the cerebral hemispheres and other parts of the brain from the corpus callosum, resulting in exposure of its upper and lower surface, which was photographed using a digital camera. As evidenced by the obtained data, the width of the trunk of the corpus callosum in men varies from 9 to 16 mm, whereas in women the difference between the minimum (11.0 mm) and the maximum (20.0 mm) values is greater than in men, when in fact there is only small difference of the arithmetic mean value. Thus, we offer to consider the lateral longitudinal strips to be the boundaries of the corpus callosum hemispherical part and the distance between them determines the width of this formation, which in average is 13.0 ± 2.5 mm in men and 14.4 ± 2.7 mm in women. In the meantime, the nature of the individual variability of the width of the corpus callosum trunk in women is more diverse than in men.

Safety of the LCP Pediatric Hip Plate in Proximal Femoral Osteotomy in Children with Cerebral Palsy.

PurposeProximal femoral osteotomy in cerebral palsy patients is a demanding procedure. The fixation of the osteotomy can fail due to the weak osteoporotic bone. The LCP pediatric hip plate with its good grip makes these procedures safe. The aims of the present study are to evaluate the radiological outcome of proximal femoral osteotomy that was fixed with the pediatric LCP in cerebral palsy patients and to raise safety issues regarding its low rate of complications.Patients and MethodsSixteen patients with cerebral palsy who were operated in our department were included in this retrospective study. Data collected from medical charts and X-ray measurements retrospectively reviewed.ResultsIn total, 16 patients (21 hips), ie, 9 males and 7 females, were included in this analysis. The mean age at the time of the index surgery was 11.9 years (5.9–18.0). The mean follow-up period was 4.78 years (1.5–8.0). Five patients had bilateral hip involvement and 11 had unilateral involvement. All patients had spastic cerebral palsy. The mean values of varus correction and de-rotation were 25° (0°–45°) and 35° (20°–50°), respectively. Neck shaft angle and the Reimer’s migration index were significantly improved postoperatively (p<0.01 for both). Seventeen hips showed complete consolidation within 14 weeks of fixation and four hips needed 16 weeks. These four hips were in three patients who were 16 years of age or older. The correlation between age at surgery and the time needed for consolidation was statistically significant (p=0.005). Avascular necrosis, revision surgeries, failure of fixation, acetabular penetration, screw loosening or fracture of the femur were not seen in this study.ConclusionThe LCP pediatric hip plate can be used safely in CP patients. The plate provides a strong stable fixation on osteoporotic bone with a low rate of complications.

Recognition cascade and metabolite transfer in a marine bacteria-phytoplankton model system.

The trophic linkage between marine bacteria and phytoplankton in the surface ocean is a key step in the global carbon cycle, with almost half of marine primary production transformed by heterotrophic bacterioplankton within hours to weeks of fixation. Early studies conceptualized this link as the passive addition and removal of organic compounds from a shared seawater reservoir. Here, we analysed transcript and intracellular metabolite patterns in a two-member model system and found that the presence of a heterotrophic bacterium induced a potential recognition cascade in a marine phytoplankton species that parallels better-understood vascular plant response systems. Bacterium Ruegeria pomeroyi DSS-3 triggered differential expression of >80 genes in diatom Thalassiosira pseudonana CCMP1335 that are homologs to those used by plants to recognize external stimuli, including proteins putatively involved in leucine-rich repeat recognition activity, second messenger production and protein kinase cascades. Co-cultured diatoms also downregulated lipid biosynthesis genes and upregulated chitin metabolism genes. From differential expression of bacterial transporter systems, we hypothesize that nine diatom metabolites supported the majority of bacterial growth, among them sulfonates, sugar derivatives and organic nitrogen compounds. Similar recognition responses and metabolic linkages as observed in this model system may influence carbon transformations by ocean plankton.

Pattern of recovery after open reduction and internal fixation of proximal phalangeal fractures in the finger: a prospective longitudinal study.

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Цель. Оценка деформативных свойств регенерата при ступенчато возрастающей и убывающей осевой нагрузке. Материалы и методы. В ФГБУ «РНЦ ВТО им. акад. Г.А.Илизарова» разработана прижизненная оценка жесткости фиксации костных отломков в аппарате Илизарова, которая основана на определении изменения расстояния между спицами, выходящими из кости, при осевой нагрузке на конечность. У больных с приобретенным (24 человека) и врожденным (21 человек) укорочением голени на этапе фиксации оценивались деформативные свойства регенерата при ступенчато возрастающей и убывающей осевой нагрузке на конечность с шагом по 5 кг за 10 секунд. Для характеристики жесткости системы “аппарат-сегмент” использовали показатель деформативности костного регенерата (Е), рассчитываемый как величина взаимного смещения спиц, проходящих через проксимальные и дистальные костные отломки, при дозированной нагрузке в 15 кг, отнесенной к высоте дистракционного регенерата (размерность величины мкм/мм×15кг). Величина деформативности (Е) костного регенерата определяется темпом дистракции и величиной удлинения кости. Результаты. Уменьшение относительной деформативности и остаточной деформации регенерата на этапе фиксации отражает повышение жесткости регенерата в системе «аппарат-сегмент». У пациентов с врожденной этиологией заболевания первые 2-3 недели фиксации являются «периодом риска» возникновения деформаций костного регенерата. У пациентов с приобретенной этиологией заболевания такой «период риска» отсутствует. Исследование деформативных свойств регенерата с использованием ходьбы как функциональной пробы является количественным критерием адекватности нагрузки и жесткости системы «аппарат-сегмент». Результат пробы расценивается как положительный, если остаточная деформация уменьшается после ходьбы. Можно говорить о повышении предела текучести и рекомендовать больным увеличение осевой нагрузки на конечность. Результат пробы расценивается как отрицательный, если остаточная деформация увеличивается после ходьбы – рекомендуется уменьшать осевую нагрузку на конечность или повышать жесткость системы «аппарат–сегмент». Заключение. Исследование деформативных свойств регенерата является дополнительной методикой оценки дистракционных регенератов. Ключевые слова: дистракционный регенерат, жесткость системы «аппарат-сегмент», деформативность регенерата, функциональные пробы. Purpose. To evaluate the deformable characteristics of the regenerated bone for stepwise increasing and decreasing axial load. Materials and Methods. The authors developed the intravital assessment of bone fragmental fixation stiffness in the Ilizarov fixator at FSBI RISC “RTO”; the assessment is based on determining the changes in the distance between the wires coming out of bone for limb axial loading. The deformable characteristics of the regenerated bone for limb stepwise increasing and decreasing axial loading with 5 kg-increment each for 10 seconds were evaluated in patients with acquired (n=24) and congenital (n=21) shortening of the leg at the stage of fixation. The index of regenerated bone deformability (E) was used in order to characterize fixatorsegment system stiffness; the index was calculated as the value of mutual displacement of the wires inserted through proximal and distal bone fragments at the graduated load of 15 kg with respect to the height of the distraction regenerated bone (the value dimensional representation - µm/mm×15 kg). The deformability value (E) of the regenerated bone is determined by the rate of distraction and by the amount of bone lengthening. Results. A decrease in the relative deformability and residual deformation of the regenerated bone at the stage of fixation reflects an increase of the regenerated bone stiffness in fixator-segment system. The period within first 2-3 weeks of fixation is the “period of risk” of the regenerated bone deformity development in patients with the disease congenital etiology. As for patients with the disease acquired etiology, there is no such “period of risk” in them. The investigation of the regenerated bone deformable characteristics using walking as a functional test is a quantitative criterion of the adequacy of fixator-segment system load and stiffness. The test result is considered as positive if residual deformity decreases after walking. One can speak of the yield strength raising and recommend limb axial load increasing for patients. The test result is considered as negative if residual deformity increases after walking – it is recommended to decrease axial load of the limb or to increase fixator-segment system stiffness. Conclusion. Studying the regenerated bone deformable characteristics is an additional technique to evaluate distraction regenerated bones.

Study of Gross Anatomy of Human Placenta in Pregnancy Induced Hypertension

Introduction: Pregnancy induced hypertension (PIH), also referred to as Gestational hypertension is a condition of high blood pressure during pregnancy. Progression the disease causes preeclampsia and eclampsia, which are the commonest causes of maternal and fetal morbidity and mortality.Objective: The objectives of the study were to observe and measure the macroscopic changes in the placenta in pregnancy induced hypertension and to compare the placental findings of the control group. .Method: This descriptive observational study was carried out in the Department of Anatomy, Bangabandhu Sheikh Mujib Medical University (BSMMU). Forty placentas were collected from Bangladesh Institute of Research &amp; Rehabilitation in Diabetes, Endocrine and Metabolic Disorders (BIRDEM) and Bangabandhu Sheikh Mujib Medical University. Out of forty placentas, twenty were from non-hypertensive mother considered as controls and twenty from PIH mothers. Mother who had Rh-negative blood group, positive for VDRL and HbsAg and mother delivered multiple babies or babies with any visible congenital malformation were excluded. All women included in the study gave birth to a live born baby after 35 weeks of gestation by caesarian section. The macroscopic features of placentas were recorded and after that specimen was fixed in 10% formol saline. After two week of fixation, a point counting method was used on placental slices for estimation of the volume of parenchyma and non-parenchyma.Results: The general features of the control and PIH mother were statistically matched. As compared with the control group, PIH group showed no statistically significant difference in values of placental weight, volume and diameter.Mean placental weight (gm), mean volume (ml) and the mean diameter (cm) of the placental, mean absolute volume of parenchyma, mean proportional and mean absolute volume of non-parenchyma were lower in PIH group than the control group. The mean number of cotyledon of the placenta and mean proportional volume of parenchyma were higher in PIH group than control group and. These differences did not reach statistically significant level.Conclusion: Several authors has concluded that the changes in the placenta in diabetic and toxaemic mother are the reflection of some compensatory mechanism, but the present study fails to identify any statistically significant changes in PIH group in favour of such statement.Journal of Armed Forces Medical College Bangladesh Vol.10(2) 2014

Effects of Prolonged Formalin Fixation on the Immunohistochemical Detection of Infectious Agents in Formalin-Fixed, Paraffin-Embedded Tissues

Immunohistochemistry is commonly used to detect and characterize infectious agents in diagnostic pathology. The principal advantage of immunohistochemistry over other antigen detection techniques is the ability to identify antigen within the context of histologic lesions. Although epitope masking attributed to formalin fixation, especially prolonged fixation, has been considered a limiting factor in diagnostic immunohistochemistry, only a few studies have evaluated the immunohistochemical detection of infectious agents following prolonged formalin fixation. Therefore, the goal of this study was to evaluate the effects of prolonged formalin fixation on the immunohistochemical detection of 21 infectious agents. Tissue slices about 5 mm thick were fixed in 10% neutral-buffered formalin, processed, and paraffin embedded at day 1 or 2 and then at approximately weekly intervals. Three pathologists graded immunoreactivity according to a four-tier grading system: negative, weak, moderate, strong. Canine parvoviral immunoreactivity was markedly decreased following 2, 7, and 10 weeks of fixation in myocardium, small intestine, and spleen, respectively. Bovine respiratory syncytial virus immunoreactivity was markedly decreased following 7 weeks of fixation. Bartonella henselae had an abrupt loss of immunoreactivity following 9 weeks of fixation. Despite variation among time points, immunoreactivity remained moderate to strong throughout the study period for the other 18 antigens. These results suggest that prolonged formalin fixation of up to 7 weeks generally does not limit immunohistochemical detection of infectious agents. However, the effects of prolonged fixation depend on the targeted antigen and the selected antibody. The results of this study further validate the utility and reliability of immunohistochemistry in diagnostic pathology.

Effects of Prolonged Formalin Fixation on Diagnostic Immunohistochemistry in Domestic Animals

Immunohistochemistry (IHC) is routinely used in diagnostic pathology to detect infectious agents, to immunophenotype neoplastic cells, and to prognosticate neoplastic diseases. Formalin fixation is considered a limiting factor for IHC because formalin can cross-link antigens and mask epitopes. Prolonged formalin fixation is presumed to result in decreased antigen detection; however, this effect has only been evaluated with a few antibodies. The goal of this study was to evaluate the effect of prolonged formalin fixation on the immunohistochemical detection of 61 different antigens. Approximately 5-mm-thick tissue slices were fixed in 10% neutral-buffered formalin. Tissue slices were removed from formalin, processed, and paraffin-embedded at 1-day, 3-day, and then at approximately 1-week intervals. IHC was performed on all sections in tandem after all tissues were processed. Immunoreactions were evaluated by three pathologists according to a four-tier grading system. Immunoreactivity of cytokeratin 7, high-molecular-weight cytokeratin, and laminin was diminished by prolonged formalin fixation. However, immunohistochemical reactivity remained moderate to strong with up to 7 weeks of fixation for all other antibodies. These results suggest that prolonged formalin fixation has minimal effects on antigen detection for most commonly used antibodies. These results further validate the use of IHC in diagnostic pathology.

Grading system for articular surface degeneration of zygapophysial (Z) joints following induced segmental hypomobility in the rat

Articular surface degeneration (ASD) of the Z joint cephalad articular facets (CAFs) is characterized by roughening, pitting, and remodeling. These changes have been previously found in hypomobile Z joints of rats. Our objective was to refine the method of grading ASD for use in large scale studies. Left and right L4‐S1 CAFs of 6 randomly selected spines (45 CAFs) of control and experimental rats were assessed. The experimental animals had undergone 8 weeks of fixation, using an established, IACUC approved, rat model, in which 3 contiguous segments (L4, L5, L6) were fixed with a specially engineered, surgically implanted, vertebral fixation device. Using a decision tree developed to score overall CAF degeneration, the CAFs were graded under dissection microscopy by 2 observers (blinded to each other and to their own initial scores) to determine: number of regions and size of remodeling; number, location, and depth of pits; and severity and size of roughening. The observers scored the spines on 2 occasions separated by at least 7 days. Weighted kappa showed substantial intra‐observer (k=0.77, SE 0.1) and inter‐observer agreement (first measurement, k=0.72, SE 0.14; second measurement k=0.71, SE 0.14), indicating that the grading system can be used in future studies assessing ASD of CAFs. Support: NIH/NCCAM (Grant #s 1R21 AT00784 and U19 AT002006).

Grading system for osteophytic changes in zygapophysial (Z) joints following induced segmental hypomobility in the rat

Osteophytic changes (OCs) have been identified on the cephalad articular processes (CAPs) of hypomobile zygapophysial (Z) joints of rats. Our objective was to refine the method of grading OCs for use in a large scale study. Thirty‐eight Z joint CAPs (left and right L4, L5, L6, and S1) of control and experimental rats were assessed. The experimental animals had undergone 8 weeks of fixation, using an established, IACUC approved, rat model, in which 3 contiguous segments (L4, L5, L6) were fixed with a specially engineered, surgically implanted, vertebral fixation device. The spines of all animals had been prepared for dissection microscopy. The CAPs were graded by 2 observers using specific OC criteria developed for this study. The lateral, cephalad, and dorsal surfaces of each CAP were systematically evaluated. Each observer graded the spines on 2 separate occasions, separated by 30 days. Intra‐ and inter‐observer reliability of grading was assessed using kappa coefficients. Results: Intra‐examiner reliability was 0.62. Inter‐examiner reliability was 0.64. We conclude that good reliability was achieved using these methods. Future studies will use a consensus procedure for segments scored differently by the two observers.Support: NIH/NCCAM (Grant #s 1R21 AT00784 and U19 AT002006).

Ulnar Nerve Palsy Following Fracture of the Distal Radius in an Adolescent: A Case Report

In adolescents, neurovascular injury, especially ulnar nerve injury, is rare with fracture of the distal radius. We present a 14-year-old boy who sustained fracture of the distal radius in his right wrist, who also had symptoms of ulnar nerve injury. Close reduction with percutaneous pinning and cast to fix the distal radius fracture was done immediately. Then, we decided to observe the recovery of the nerve injury without providing any emergent nerve exploration. Bone union was achieved after 8 weeks of fixation, and the function of the ulnar nerve was restored completely after 16 weeks of observation. The possibility of ulnar nerve injury should be considered following fracture of the distal aspect of the radius, and we recommend observing the recovery of nerve injury, with no need for emergent nerve exploration.

Effect of fixation time on leaching of copper-ethanolamine based wood preservatives

Fixation in copper-ethanolamine treated Norway spruce wood is finished in the first or in the second week after impregnation depending on the concentration of wood preservatives used. However, copper losses increased after four weeks of fixation again, presumably due to lignin depolymerisation caused by ethanolamine.

Degenerative Changes Following Spinal Fixation in a Small Animal Model

Objective The objective of this study was to evaluate changes of the lumbar vertebral column following fixation. Design Using an established small animal (rat) model of spinal fixation (hypomobility), 3 contiguous lumbar segments (L4, L5, L6) were fixed with a specially engineered vertebral fixation device. Spinal segments of control rats were compared with those of animals with 1, 4, or 8 weeks of fixation. Subgroups of these fixation animals subsequently had the fixation device removed for 1, 2, 4, 8, or 12 weeks to evaluate the effects of attempting to reestablish normal forces to the vertebral segments following hypomobility. Setting This Institutional Animal Care and Use Committee (IACUC) approved study was conducted in a university animal facility. Animals Eighty-seven animals (23 controls animals and 64 fixation animals) were used in this study. Main Outcome Measures Outcome measures were degenerative changes of the vertebral bodies (VBs) and intervertebral disks (IVDs), zygapophysial (Z) joint osteophyte formation, and Z joint articular surface degeneration (ASD). Changes found in vertebral segments that were fixed (hypomobile) were compared with changes in adjacent nonfixed vertebral segments, and changes among fixation animals were compared with nonfixed controls. Main Results Very few degenerative changes were identified on the VBs and IVDs. Z joint changes were significant, both for osteophyte formation (analysis of variance [ANOVA], P < .0001) and ASD (ANOVA, P < .0001). Fixed segments had more degenerative changes than nonfixed segments for all Z joint parameters (ANOVA, P < .0001). Osteophyte formation and ASD were directly dependent on duration of fixation. Conclusions These findings indicate that fixation (hypomobility) results in time-dependent degenerative changes of the Z joints.

Measurement of hemoglobin in long-term fixed erythroid cells: application development for cell science experiments in microgravity

Studying the effects of microgravity on cell differentiation will enhance our understanding of fundamental biology and is indispensable for a sustained space program. Rauscher murine erythroleukemic cells were chosen as a model system to study erythroid cell differentiation aboard the International Space Station because these cells undergo differentiation in response to the natural inducer, erythropoietin, as well as various chemical-inducers. We have now developed a method to quantify hemoglobin in Rauscher cells after weeks of fixation and storage required for such space biology experiments. By exploiting the pseudoperoxidase activity of hemoglobin and by using reagents that yield a soluble chromophore that freely passes out of fixed cells, we developed a highly specific and sensitive assay applicable to cells fixed as long as 4 months.

Immunohistochemical Detection of Uroplakin III, Cytokeratin 7, and Cytokeratin 20 in Canine Urothelial Tumors

Immunohistochemistry for uroplakin III (UP III), cytokeratin 7 (CK 7), and cytokeratin 20 (CK 20) using commercially available antibodies was done in normal canine urinary bladder and 72 canine urinary bladder tumors that had been fixed in formalin and embedded in paraffin. Prolonged fixation (3–28 days) did not significantly alter the immunostaining for UP III. There was moderate reduction in the intensity for CK 7 and CK 20 after 1 week of fixation. UP III was detected in superficial (umbrella) cells and some intermediate cells of the normal urinary bladder, 7 of 7 transitional cell papillomas (TCPs), 50 of 55 transitional cell carcinomas (TCCs), and 4 of 5 metastatic TCCs. Staining was typically outlined in the plasma membrane, but diffuse or focal cytoplasmic staining was also observed. Intracytoplasmic lumina were usually positive for UP III. One squamous cell carcinoma of the bladder, 4 nonepithelial bladder tumors, and 285 nonurothelial tumors from different nonurinary locations were negative for UP III. CK 7 was detected in 7 of 7 TCPs, 53 of 54 TCCs, and 5 of 5 metastatic TCCs. The staining for CK 7 was diffuse cytoplasmic. CK 20 was detected in 1 of 7 TCPs, 37 of 54 TCCs, and 1 of 5 metastatic TCCs. The staining with CK 20 was cytoplasmic and weaker than with antibodies to UP III or CK 7. There was concurrent expression of UP III, CK 7, and CK 20 in 36 of 54 TCCs. UP III is a specific and sensitive marker for canine transitional epithelial (urothelial) neoplasms, detecting 91% of TCCs. Negative results may be observed with anaplastic tumors.

Immunohistochemical detection of uroplakin III, cytokeratin 7, and cytokeratin 20 in canine urothelial tumors.

Immunohistochemistry for uroplakin III (UP III), cytokeratin 7 (CK 7), and cytokeratin 20 (CK 20) using commercially available antibodies was done in normal canine urinary bladder and 72 canine urinary bladder tumors that had been fixed in formalin and embedded in paraffin. Prolonged fixation (3-28 days) did not significantly alter the immunostaining for UP III. There was moderate reduction in the intensity for CK 7 and CK 20 after 1 week of fixation. UP III was detected in superficial (umbrella) cells and some intermediate cells of the normal urinary bladder, 7 of 7 transitional cell papillomas (TCPs), 50 of 55 transitional cell carcinomas (TCCs), and 4 of 5 metastatic TCCs. Staining was typically outlined in the plasma membrane, but diffuse or focal cytoplasmic staining was also observed. Intracytoplasmic lumina were usually positive for UP III. One squamous cell carcinoma of the bladder, 4 nonepithelial bladder tumors, and 285 nonurothelial tumors from different nonurinary locations were negative for UP III. CK 7 was detected in 7 of 7 TCPs, 53 of 54 TCCs, and 5 of 5 metastatic TCCs. The staining for CK 7 was diffuse cytoplasmic. CK 20 was detected in 1 of 7 TCPs, 37 of 54 TCCs, and 1 of 5 metastatic TCCs. The staining with CK 20 was cytoplasmic and weaker than with antibodies to UP III or CK 7. There was concurrent expression of UP III, CK 7, and CK 20 in 36 of 54 TCCs. UP III is a specific and sensitive marker for canine transitional epithelial (urothelial) neoplasms, detecting 91% of TCCs. Negative results may be observed with anaplastic tumors.

Effects of Mandibular Distraction Osteogenesis on the Inferior Alveolar Nerve: An Experimental Study in Monkeys

A series of experimental studies were performed in monkeys to study the effect of mandibular distraction osteogenesis on the inferior alveolar nerve at different times before and after distraction. A mandible osteotomy was performed and distraction was carried out unilaterally in 10 young rhesus monkeys and bilaterally in six. The intact nerves on the contralateral side of the 10 monkeys were used for the control. Care was taken to avoid destroying the integrity of the inferior alveolar nerve during the surgical procedure. After a 5-day latency period, the distraction device was activated at a rate of 0.5 mm twice each day for 15 days. Sensory nerve action potential testing was applied before and 1 day after the operation, at completion of distraction, and at 2, 4, 6, 9, and 12 weeks of fixation. Necropsy was performed at the completion of distraction and 2, 4, 6, and 12 weeks of fixation. The mental nerves were taken, sectioned, and stained with lead citrate and uranyl acetate, and examined with a transmission electron microscope. The inferior alveolar nerves in the distraction gap were obtained, and paraffin slides were made and stained with hematoxylin and eosin, Luxol fast blue, and Bodian methods. The authors found that immediately after the mandible osteotomy, most nerves showed signs of slight acute injury; the latency was increased by 5.553 percent, and the amplitude was decreased to 1808 microV. This might be caused by the surgical procedure or by compressions produced by swelling tissues around the nerves. When distraction was completed, the latency was prolonged for an average of 22.18 percent, and the amplitude average had attenuated to 28.54 percent (804 microV) of the preoperative value on the distracted side. Most nerve fibers exhibited signs of degeneration, such as myelin disruption, swelling of cell organs greatly increased in axoplasm, axon tearing, and myelin fragments engulfed by macrophages. These were nerve reactions to the tensions produced by mandible lengthening. As time elapsed, the nerve's action potential recovered gradually because of its repairing ability, the latency shortened, amplitude increased, Schwann cells proliferated and formed new myelin sheaths, and the tearing axons reconnected. After 12 weeks of consolidation, there was still a latency of 12.384 percent prolongation because of the prolonged conduction distance, and the average amplitude was restored to 2786 microV, the approximate preoperative value. The nerve seemed to be repaired completely; its myelin thickness, axon diameter, and ultrastructure were all similar to those of the control. It was concluded that mandibular distraction osteogenesis can produce some degree of harmful effects on the function and structure of inferior alveolar nerves, but it is reversible and relatively slight. Along with the regeneration of the nerve's myelin and axon, the nerve function can gradually rehabilitate to a normal level.

Three Weeks of Kirschner Wire Fixation for Displaced Lateral Condylar Fractures of the Humerus in Children

The authors assessed whether a period of 3 weeks, rather than the commonly used 6 weeks, of smooth Kirschner wire fixation and cast immobilization of the elbow was sufficient to achieve union of displaced fractures of the lateral humeral condyle treated by open reduction. The authors found only one nonunion in a case series of 104 children treated with 3 weeks of fixation. Infections occurred in two children (2%). Late review of 63 children (61%) showed abnormalities of elbow shape in 28 (44%) and wide surgical scars in 43 (68%). The abnormalities of elbow shape were mainly due to overgrowth of the lateral humeral condyle, to the formation of excessive amounts of bone over the outer surface of the condyle, or both. The authors' findings indicate that a period of 3 weeks of smooth Kirschner wire fixation and elbow immobilization is sufficient to achieve healing in most displaced fractures of the lateral humeral condyle treated by open reduction. The findings also indicate that new strategies are needed to reduce the occurrence of overgrowth of the lateral condyle, excessive formation of bone over the condyle, and wide scars.

Heart valves from pigs and the porcine endogenous retrovirus: Experimental and clinical data to assess the probability of porcine endogenous retrovirus infection in human subjects

Objective: Replacement of heart valves in human subjects has become a routine procedure in cardiac operations. We sought to investigate whether commercially available glutaraldehyde-fixed porcine heart valve prostheses cause porcine endogenous retrovirus infection in human subjects because recent studies revealed that human cells can be infected with porcine endogenous retrovirus. Methods: Blood samples of 18 patients who underwent aortic or mitral valve replacement with porcine heart valves were collected 6 months to 3 years after operation and tested for porcine endogenous retrovirus by means of polymerase chain reaction and reverse transcriptase–polymerase chain reaction. In addition, we tried to trace porcine endogenous retrovirus in 3 commercially available, glutaraldehyde-fixed, porcine heart valves. Results: Porcine endogenous retrovirus can be easily detected in native porcine heart valves and degrades completely within 1 week of fixation in glutaraldehyde. In all 3 commercially available porcine heart valves, no traces of porcine endogenous retrovirus were found. All blood samples showed negative test results for the porcine endogenous retrovirus genome. Conclusion: Our results indicate that glutaraldehyde fixation of porcine heart valves reliably prevents cross-species transmission of porcine endogenous retrovirus. (J Thorac Cardiovasc Surg 2001;121:697-701)