Titanium as a biomaterial for ossicular replacement: results after implantation in the middle ear of the rabbit

The middle ear poses unique challenges when finding suitable materials for ossicular reconstruction, primarily because of its link to the external environment via the eustachian tube and, hence, its greater exposure to infectious agents. In this study, the biocompatability of titanium was examined in the middle ear of rabbits by using light and scanning electron microscopy. Implants were placed as middle ear prostheses or as free implants. These were inspected at 28 days, 84 days, 168 days, 336 days and 504 days following implantation for mucosal coverage, percent epithelization and any sign of foreign-body reaction. After 28 days, the prostheses were covered by regular mucosa. Although a majority of the free implants took up to 336 days for complete epithelialization, some of the free implants were not epithelialized even at day 504. There were no inflammatory cells observed on the surface of the material, nor were unusual amounts of fibrous tissue seen. In addition, the titanium material exhibited an affinity toward bone. The results of this animal experiment indicate that titanium is a favorable material for ossicular replacement prostheses.     

CT appearances of ossicular injuries

Trauma of the ossicular chain is a frequent complication of temporal bone injury. Skull trauma from blows to the temporal, parietal, or occipital region (with or without fracture of the temporal bone) is the main cause of ossicular injury; other modes of injury are rare. Ossicular injury usually occurs as a dislocation, of which there are five types: incudostapedial joint separation, incudomalleolar joint separation, dislocation of the incus, dislocation of the malleoincudal complex, and stapediovestibular dislocation. Fracture of the malleus, incus, or stapes is uncommon. High-resolution computed tomography is the method of choice for evaluation of ossicular trauma. Joint separation and fracture of the stapes are seen on axial images; coronal images may aid visualization. Both axial and coronal images are needed for evaluation of a dislocated malleus or incus. Fracture of the malleus or incus is detected with axial or coronal images; reformatted images may also be useful.     

Tube device for facilitating distal anastomosis in aortic arch replacement

The technique of placing an inverted graft into the descending thoracic aorta facilitates and secures the distal anastomosis in aortic arch replacement, especially in the anastomosis beyond the transverse arch. We developed a simple technique using a pair of thin-walled tubes to enable the arch graft, with its four branches, to be smoothly inserted into the flaccid, normal-caliber descending aorta. The use of these tubes simplified the procedure, resulting in time saving.     

Synthetic implants in the reconstruction of the ossicular chain

OBJECTIVE: To determine whether there is a relationship between overexpression of c-met oncoprotein and stage of human gastric mucosal lesions, and its significance. METHOD: Immunohistochemical staining was used in 157 cases of endoscopic biopsies with c-met monoclonal antibody, S-19, which was raised against the human c-met gene product. RESULTS: overexpresion of c-met oncoprotein was detected in 3/30 cases (10%) of superficial gastritis, 4/33 cases (12.1%) of chronic atrophic gastritis, 10/31 cases (32.3%) of intestinal mataplasia, 10/30 cases (33.3%) of dysplasia, and 10/30 cases (33.3%) of gastric carcinoma. The positive staining rate was higher in intestinal mataplasia (54.8%), dysplasia (56.7%), carcinoma (53.3%) than in two kinds of simple chronic gastritis (P < 0.05). The positive staining was obviously located in luminal membrane of mucosal cells. The positive cells were mainly situated in proliferative cell zone of gastric glands. Moreover, the weak staining only in this zone was shown in two of the three normal mucosa. CONCLUSIONS: The overexpression of c-met may be involved in proliferation of gastric mucosa. It is possible that persistent overexpression of c-met oncoprotein is associated with the malignant transformation of gastric mucosal cells.     

Accuracy of an electromagnetic measurement device and application to the measurement and description of knee joint motion

A nonsteroidal antiinflammatory drug, 5-bromo-2-(4-fluorophenyl)-3-(4-methylsulfonylphenyl) thiophene (BFMeT), induced ileal ulcers in rats after oral administration, while no ulcers were observed after subcutaneous injection. The ileal ulcer formation in BFMeT-treated rats was examined to correlate the administration of cultures of Lactobacillus acidophilus or Bifidobacterium adolescentis with intestinal bacteria in the ileal contents and lipid peroxidation of the small intestinal mucosa. Ileal ulcers were observed in more than 85% of the rats treated with BFMeT at a dose of 1,000 mg/kg when they were given tap water as drinking water. The incidence of ulcer formation was repressed by giving culture supernatants of L. acidophilus or B. adolescentis as drinking water, but not by giving the cell suspension as drinking water. Gram staining of the ileal contents of normal rats revealed that 97% of the stained bacteria were gram-positive rods and only 1.5% were gram-negative rods. The percentage of gram-negative rods 72 hr after BFMeT administration was 49.8% and increased over 30-fold in BFMeT-treated rats. However, the percentage of gram-negative rods was 9.7 % or 16%, respectively, in rats taking culture supernatants of L acidophilus or B. adolescentis. In addition, thiobarbituric acid-reactive substances in the ileal mucosa increased significantly in the rats given tap water for 72 hr after BFMeT treatment, but not in rats given the culture supernatants of L. acidophilus or B. adolescentis. Since BFMeT induced an unbalanced intestinal microflora, the effect of antibiotic treatment on ulcer formation in rats was examined. The magnitude of the ulcer formation in the antibiotic-treated rats was, in decreasing order, metronidazole >none > kanamycin > a mixture (bacitracin, neomycin and streptomycin). These results suggest that the intestinal microflora plays an important role in ulcer formation and that a metabolite(s) of L. acidophilus and B. adolescentis inhibits ileal ulcer formation by repressing changes in the intestinal microflora and lipid peroxidation in BFMeT-treated rats.     

Epitympanic malleus fixation: correction without disrupting the ossicular chain

The preoperative diagnosis of malleus fixation can be made consistently with a pneumatic otoscope. Nontympanosclerotic epitympanic malleus fixation, for the most part, has been corrected by disrupting the ossicular chain and then reconstructing the sound-conducting mechanism. Once the diagnosis of malleus fixation is established, the surgical approach should be modified to cope with the fixed malleus. A wide, inferiorly based tympanotomy flap affords ample access to the epitympanum and permits definitive resolution of the associated conductive hearing loss. Atticotomy and discreet osteotomy can free the fixed malleus and preserve continuity of the osscular chain in over 90 percent of the patients with this syndrome. Experience for 46 patients having bony epitympanic malleus fixation, both congenital and acquired, was examined in concluding that the anatomical continuity of the ossicular chain can and should be maintained in most patients. The residual air-bone gap is less with an intact, though modified, ossicular chain than it is with a chain that has been reconstructed.     

Augmented anterior cruciate ligament replacement with the Kennedy-LAD (ligament augmentation device)--long term outcome

The ligament augmentation device (Kennedy-LAD) is used to protect tendon grafts during the posttransplantation decrease in strength in anterior cruciate ligament (acl) reconstructions. The augmentation with the LAD is based on the concept of load sharing. Since 1983 we used the LAD in acl-reconstructions in 856 patients. In 63 cases we had to treat complications like infection (8), recurrent effusions (21), arthrofibrosis (34). The overall results are good with respect to stability, regain of strength and sports activity. In 73 cases resurgery was necessary because of synovitis (7), LAD-rupture due to re-injury (9), fatigue-rupture of the LAD (22), meniscal tears (35), 2.7 +/- 2.3 years (range: 2 months to 10 years) after LAD implantation. Modern techniques in acl reconstruction lead to comparable results without synthetic augmentation. Therefore, we now recommend the use of a LAD only in cases of repeated acl replacement with week tendon grafts, to avoid an allograft.     

Research on electromagnetic properties of electromagnetic stirring roller

Using computer simulation and test measurements,the relationship between the electromagnetic properties of an electromagnetic stirring roller and the roller structure parameters was analyzed and compared. The distribution of the magnetic field,magnitude of the electromagnetic force,and matched-load characteristics were systematically investigated at different parameter values for the induction coils,iron core,shield,and roller sleeve.The results indicate that the change in the electromagnetic force with stirring frequency is non-linear and has a maximum value higher than 10 Hz; the electromagnetic force largely depends on the diameter of the core; and there is a mutual restriction relationship between the two-phase imbalance and the electromagnetic force.     

辊式电磁搅拌器电磁特性研究

针对辊式电磁搅拌器关键结构参数与电磁特性之间的相互关系,通过计算机仿真计算和试验测量的方法分别进行了分析和对比研究。着重就辊式搅拌器线圈、铁芯、屏蔽罩、辊套等参数对磁场分布、电磁力大小、负载特性差异等的影响规律进行了深入系统的计算和分析。研究发现,电磁力随着搅拌频率增加而先增大后减小,最佳频率在10Hz以上;铁芯直径参数对电磁力具有决定性影响;电磁力大小与相平衡之间存在相互制约的关系。     

电磁软接触结晶器电磁冶金特性研究

钢的软接触电磁连铸结晶器按其结构的不同可分为切缝式和无缝式2种,其中切缝式软接触结晶器研究较多.针对3种不同的切缝式软接触结晶器结构形式,利用三维数值模拟的方法,围绕其内部电磁冶金特性展开讨论.研究结果表明,结晶器切缝形式、水冷方法对结晶器内磁感应强度、电磁力的大小和分布,以及系统内的时间平均功率损失均有影响.     

The tympanic membrane/ossicular chain Block implant - early impression

Twenty-six tympanic membrane-ossicular chain implants have been used during a twelve-month period in the reconstruction of middle ears which had been affected by tympanosclerosis, inflammatory processes and cholesteatoma. The results which have been achieved, both from the point of view of anatomy and function, are presented and changes observed in the post-operative period are described. It is suggested that alternative methods of preservation of these grafts and modifications in technique may give more consistent results.     

Operative repair of the traumatically disrupted ossicular chain (author's transl)

Consequent to the large number of skull injuries following traffic accidents, a significant number of patients experience traumatic disruption of the ossicular chain. Although most of these injuries can be managed by standard otologic procedures, this communication deals with three special clinical problems. Although not previously encountered, the diagnosis in the first could be made by otoscopy. In the second, infracture of the malleolar head had produced injury to the facial nerve which was exposed in its horizontal course. Although transposition of the malleus was required in repair, significant interference with hearing had not occurred since a spontaneous tympanoincudopexy had been produced by the injury.     

Abnormal branching of facial nerve with ossicular anomalies: report of two cases

Two cases with almost identical anomalies of the facial nerve and ossicles were reported. The two girls, ages 9 and 14 years, with unilateral hearing loss underwent exploratory tympanotomy. A huge suprameatal spine and tumor-like swelling of the facial nerve at the tympanic portion as well as its abnormal branching at the pyramidal bend were noted; one of the branches of the facial nerve appeared on the surface of the temporal bone running through the tympanomastoid suture. The distal parts of the long process and lenticular process of incus were missing as if they were eroded by the swollen facial nerve, and the superstructure of the stapes also was absent. No anomaly was seen in any other part of their ears or bodies. This specific type of anomaly is considered rare and important in that surgeons may misdiagnose the swollen facial nerve as a tumor, resulting in facial nerve paralysis due to injury or unnecessary biopsy.     

Implantation and decidualization in rodents

This article reviews the main events of embryo-implantation and decidualization in rodents. In common laboratory rodents the embryo attaches to the uterine epithelial lining, usually on days 4 to 6 of pregnancy. A progressive degree of proximity between trophoblast and epithelium occurs until the epithelial cells undergo apoptosis and detach from the basement membrane. During the attachment stage, the spindle-shaped connective tissue cells that underlie the epithelium next to the embryos transform into polyhedral and closely packed decidual cells. Following the epithelial detachment and the breaching of the basement membrane the embryo is thus in direct contact with decidual cells. These cells accumulate organelles associated with synthesis of macro-molecules, intermediate filaments, and eventually lipid droplets and glycogen. Another remarkable feature of decidual cells is the establishment of gap and adherens intercellular junctions. Differentiation of fibroblasts into decidual cells advances antimesometrially and mesometrially, creating in the endometrium several regions of cells with different morphology. The whole phenomenon of decidualization which is normally triggered by the embryo can be artificially induced in pseudo-pregnant or hormonally-prepared animals with the use of diverse stimuli. The uterine epithelium is probably responsible for the transduction of the initial stimulus. Prostaglandins have been shown to be important in the induction of decidualization. More recently other substances such as leukotrienes, platelet-activating factor (PAF), and transforming growth factor (TGF) have been thought to play a role in induction. Much evidence points to prostaglandin production by the decidual cells. New proteins such as a luteotropic factor, desmin, and other molecules were shown to be produced after rat stromal cells undergo decidual transformation. The extracellular matrix of the mouse decidua contains very thick collagen fibrils. Mouse decidual cells are also very active in phagocytosing the thick fibrils, contributing to the remodeling and involution of the decidua that accompanies embryonic growth. Radioautographic data indicates that mouse decidual cells produce and secrete collagen and sulfated proteoglycans.     

Biological effects of electromagnetic fields

Since several epidemiological studies have indicated an elevated risk for certain types of cancer in both living and working environments where exposure to an extremely low-frequency electromagnetic field (ELF) occurs, public concern about ELF has been increasing because it is impossible to imagine life today without electricity. We reviewed studies on biological effects of ELF with respect to their cytological and biochemical effects, including mutagenicity, clastogenicity and carcinogenicity. The studies can be summarized as follow: 1) There is evidence that outer surface of the cell membrane is the primary locus for ELF-induced cellular alterations. 2) ELF modulate the proliferation of normal as well as transformed cells in vivo and in vitro. The magnitude of the proliferative effects depends on ELF intensity, exposure duration and other cellular factors. 3) No studies clearly demonstrate deleterious effects of ELF exposure on mammalian reproduction and development, but several suggest such effects. 4) Reported evidence does not demonstrate that the ELF acts as a cancer initiator. However, it might act as a promoter or affect tumor progression. Further observations and epidemiological studies of ELF must be accompanied by laboratory experiments to evaluate biological and health effects.