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Biomedical subjects

Eitan Melamed

Publications and source records attributed to Eitan Melamed.

8 recordsLinked to original sources
PubMed2006

Repair of articular cartilage lesions in aged chickens by allogeneic transplantation of fresh embryonic epiphyses.

INTRODUCTION: The potential of fresh whole chick epiphyses of embryonic origin to serve as implant material for cartilage defects of aged chicken was tested. MATERIALS AND METHODS: Fresh epiphyses of 11-day-old embryos were collected from 24 animals and transplanted into defects created in the weight-bearing areas of tibiotarsal joint cartilage of 2-year-old chicks. Upon sacrifice, samples were examined macroscopically and microsections were prepared for histology. RESULTS: Macroscopically, control defects remained empty at all the time intervals. Defects of the experimental group were, on the other hand, filled with cartilaginous tissue as early as 2 weeks posttransplantation, although individual epiphyses could still be noted in the implant tissue. At 4 weeks and later, defects were filled with cartilaginous material indistinguishable from hyaline cartilage. Histologically, all grafts remained within the defect's pits, showing mitotic and metabolic activity typical to proliferating hyaline cartilage. The engrafted epiphyses showed a partial incorporation and integration with the surrounding host tissues already at 2 weeks. At 4 weeks and later, the integration was complete. CONCLUSIONS: It is concluded that a chick embryonic epiphyseal cartilage is suitable as a graft source for articular cartilage transplantation. The embryonic epiphyses provide immediate inherent stability to the graft and supply a good mix of mesenchymal progenitor cells responsible for the high rate of cell proliferation and adhesion to the differentiated committed chondrocytes of the host that create the typical favorable chondrogenic milieu. Based on the present findings, it is postulated that human embryonic epiphyses may, in the future, represent an alternative source to the commonly used techniques of hyaline cartilage repair.

Animals↗
PubMed2005

Influence of personal armor on distribution of entry wounds: lessons learned from urban-setting warfare fatalities.

BACKGROUND: This study was undertaken to examine the distribution of entry wounds resulting from firearms and shrapnel in soldiers wearing military personal armor systems (MPAS) in low-intensity urban combat conditions. METHODS: Data were collected for a retrospective analysis on all combat fatalities sustained by the Israeli Defense Force (IDF) between March 30, 2002, and April 22, 2002, during Defensive Shield Operation in the West Bank. Twenty-six of the 30 fatalities were evaluated in the Israeli National Center of Forensic Medicine. RESULTS: A total of 149 entrance wounds were divided into shrapnel and bullet groups. The "face-neck" region had the highest density rate compared with other body regions in both shrapnel and bullet groups (2.97 and 2.41, respectively; p < 0.0001). In both groups, the overall prevalence of anterior injuries was significantly higher than posterior ones (78.9% vs. 21.1% in the shrapnel group and 68.5% vs. 31.5% in the bullet group, p < 0.001). However, anterior and posterior chest injuries had a reverse yet more even distribution (43.8% and 56.2% in the bullet group and 40% and 60% in the shrapnel group, respectively; p < 0.001). The difference in the average diameters of entry wounds in the covered versus uncovered regions (0.79 +/- 0.42 cm vs. 0.73 +/- 0.29 cm, respectively) was not statistically significant (p = 0.11). CONCLUSION: The use of MPAS turned the face-neck region into the most vulnerable body part, as shown by its prominent density rate, especially in the shrapnel group. MPAS designed for urban setting warfare should provide maximal shielding both to the anterior and posterior chest regions. The diameter of entrance wounds in the covered versus the uncovered areas was not statistically significant, suggesting that only a minor deformation of the bullet takes place while traversing the Kevlar vest.

Forensic Ballistics↗
PubMed2005

Use of a novel joint-simulating culture system to grow organized ex-vivo three-dimensional cartilage-like constructs from embryonic epiphyseal cells.

A method for growth and maintenance of vital cartilaginous tissue is necessary for cartilage repair by in-vitro produced biologic implants. A previously tested perfusion system simulating joint activity was used. Whole epiphyses collected from thirty 11-day-old chick embryos were divided into two groups. One group was grown in a tissue culture dish for 10 days. The other group was placed in a perfusion system termed a joint-simulating device (JSD). After a period of 10 days, histology and immunohistochemistry were performed on five epiphyses from each group. Histologically, epiphyses grown in the device coalesced into a homogenous three-dimensional mass. The bridging tissue between individual epiphyses was highly cellular (PCNA staining positive) and was composed of mesenchymal stem cells as shown by expression of FGF receptor 3. No such tissue formed between epiphyses in the tissue culture dish and the epiphyseal cores were shown to be necrotic. The rest of the epiphyses were evaluated for radioactive sulfate incorporation into glycosaminoglycans (GAGs). A tenfold increase in sulfate incorporation occurred in epiphyses grown within the JSD as compared to the traditional culture method. In conclusion, embryonic epiphyses could be a suitable source for the ex-vivo growth of tissue-engineered cartilage constructs that might later be used as an in-vivo cartilage implant. The joint simulating device effectively maintains cartilage viability and bioactivity for as long as 10 days.

Animals↗
PubMed2004

Restoration of arthritic cartilage defects using autologous chondrocytes transplantation is superior to cartilage-paste graft in rabbits.

This study compared the articular cartilage repair potential of cultured chondrocytes transplantation with bone-cartilage paste-graft in the resurfacing of full-thickness defects without breaching of the subchondral bone plate in rabbit knees. A 5 x 5-mm articular cartilage defect was created in the patellar groove of the femur. Three months following creation, the defect was filled with cultured autologous chondrocytes (group 1) or bone-cartilage paste (group 2). A control group of untreated defects was followed for 1 year. The reparative tissue was analyzed macroscopically, histologically, and by immunohistochemistry 3-12 months post-transplantation. The surfaces of the reparative tissue in group 1 were smooth, and the defects were filled with reparative tissue that resembled hyaline cartilage. The composition of the repair tissue more closely resembled cartilage, as demonstrated by cartilage-specific stains. In contrast, the reparative tissue in group 2 was fibrous and exhibited markers of mesenchymal stem cells and bone formation. Transplantation of cultured chondrocytes into a full-thickness defect in the rabbit generates a biologic substitute tissue that resembles native articular cartilage with living cells capable of synthesizing the surrounding cartilage matrix. In contrast, analysis of the healing response to the paste-graft technique failed to show cartilage-like characteristics. This information may be clinically applicable to direct the use of these treatments in chondral injuries.

Animals↗
PubMed2004

Clinical presentation and anatomic position of L3-L4 disc herniation: a prospective and comparative study.

OBJECTIVE: A prospective, controlled cohort study was conducted to assess the anatomic transverse location and clinical presentation of L3-L4 disc herniation compared with lower lumbar levels. METHODS: This study prospectively identified 37 patients diagnosed with L3-L4 disc herniation (study group) and 52 patients diagnosed with L4-L5 and L5-S1 herniation (control group). The following clinical data were collected: age, femoral stretch test, motor strength, sensation, and deep tendon reflexes. The anatomic transverse location of the disc fragments was assessed by computed tomography or magnetic resonance imaging and was classified as either central, posterolateral, foraminal, or far lateral. RESULTS: The patients in the study group were older than the patients in the control group, and neurologic deficit was more common. The transverse location was foraminal and extraforaminal in 59% of the study group compared with 27% of the control group. These differences were statistically significant. CONCLUSIONS: The incidence of foraminal and far lateral disc herniation is significantly higher at the L3-L4 level compared with lower lumbar levels. When examining an older patient complaining of thigh pain, special attention should be given to the quadriceps strength, patellar reflex, and femoral stretch test. The L3-L4 foraminal and extraforaminal area should be assessed carefully.

Adolescent↗