Development of a Rat Model of Sick Sinus Syndrome Using Pinpoint Press Permeation.

OBJECTIVE: Sick sinus syndrome (SSS) is one of the most common causes of cardiac impairment necessitating pacemaker implantation. However, studies of SSS pathogenesis are neither comprehensive nor conclusive due to limited success in achieving a stable rat SSS model. Here, we modified pinpoint press permeation to establish a stable rat SSS model. METHODS: We randomly assigned 138 male Sprague-Dawley rats into three groups: normal control (n = 8), sham (n = 10), and SSS (n = 120). Postoperatively, the SSS group was further divided into SSSA (n = 40), SSSB (n = 40), and SSSC (n = 40), based on reduction in heart rates by 20-30%, 31-40%, and 41-50%, respectively. We also assessed histomorphological characteristics and hyperpolarization-activated cyclic nucleotide-gated cation channel 4 (HCN4) expression in the sinoatrial node (SAN) at 1, 2, 3, and 4 weeks after surgery. RESULTS: Mortality was statistically higher in SSSC compared to SSSA and SSSB (7.5% versus 90.0% and 87.5%; P < 0.05). Heart rate in SSSA was gradually restored to preoperative levels by week 4 after surgery. In contrast, heart rate in SSSB was stable at 2-3 weeks after surgery. However, we observed that the tissues and cells in SAN were severely injured and also found a time-dependent increase in collagen content and atrium myocardium in SSSB. HCN4 expression was significantly reduced at all 4 time points in SSSB, with statistically significant differences among the groups (P < 0.01). CONCLUSION: We successfully developed a rat SSS model that was sustainable for up to 4 weeks.

Arthroscopic combined medial and lateral meniscus transplantation after double-tunnel, double-bundle anterior cruciate ligament reconstruction in the same knee.

Meniscus transplantation in combination with anterior cruciate ligament (ACL) reconstruction has been used in the treatment of patients with meniscus and ACL deficiency. However, there have been no reports of arthroscopic surgery and the outcome of both medial and lateral meniscus allograft transplantation after double-tunnel, double-bundle ACL reconstruction. Herein, we report the case of a young male who received arthroscopic lateral and medial meniscectomy and ACL tibialis allograft reconstruction performed with the double-tunnel and double-bundle technique approximately 8 months after a knee injury. Approximately 4 months postoperatively he began to experience pain and weakness in the operated knee and subsequently underwent arthroscopic lateral and medial meniscus allograft transplantation in the same procedure. Second-look arthroscopy and magnetic resonance imaging revealed the meniscal allografts to have normal shape and the ACL grafts to be relatively intact at 18 and 30 months after surgery. His knee appeared stable and the range of motion was normal. Our hypothesis was that knee stability could reliably be restored with this combined procedure and the meniscal grafts and ACL graft could provide protection for each other. We suggest that medial and lateral meniscus allografts for one patient should be from the same donor. In the operation, attention must be paid to the direction of the bone tunnels used to fix the horns of the meniscal grafts to avoid communication with other tunnels in the tibial plateau.

[Clinical safety about repairing the peripheral nerve defects with chemically extracted acellular nerve allograft].

OBJECTIVE: To discuss the clinical safety about repairing the peripheral nerve defects with the acellular allogeneic nerve. METHODS: The 41 patients (male 38, female 3, age 10 - 55 years old, average 28.9 years old) who were performed chemically extracted acellular nerve allograft transplanting to repair nerve defects from 2002 to 2011. The average interval from injury to nerve repairing was 4.1 months (range, 10 hours to 9 months). There were 41 cases nerve defects including 10 brachial plexus nerves, 3 radial nerves of upper arm, 4 ulnar nerves of forearm, 12 digital and toe nerves, 2 sciatic nerves, 2 femoral nerves, 3 tibial nerves and 5 common peroneal nerves. There were 12 cases combined fractures and 20 soft tissue injury or defects. The average length of the nerve allograft to bridge the nerve defects was 6.1 cm (range, 2 - 10 cm). No immunosuppressive drugs were used in all cases. The clinical safety was evaluated through physical examination, blood biochemistry and immunity detection. RESULTS: All cases were followed up post-operation. They got primary wound healing except 2 superficial infection who got delay healing through dressings changing. No any adverse effects happened including immunological rejection, hypersensitivity reaction, deep infection, hepatotoxicity and nephrotoxicity. CONCLUSIONS: It is safe and feasible to repairing human peripheral nerve defects with chemically extracted acellular nerve allograft.

Changes in T lymphocyte subsets and intracellular cytokines after transfer of chemically extracted acellular nerve allografts.

The aim of the present study was to observe the immune mechanism underlying the rejection of chemically extracted acellular nerve allografts for use in clinical applications. A total of 128 BALB/c mice were randomly divided into a negative contrast group (NC, 32 mice), a fresh autograft group (AG, 32 mice), a fresh allogeneic nerve group (FN, 32 mice) and a chemically extracted acellular allogeneic nerve group (CEN, 32 mice). Various types of nerve grafts were implanted into the thigh muscle of BALB/C mice in the corresponding groups. At 3, 7, 14 and 28 days post-operation, the mice (8 cases from each group) were sacrificed and their spleens were extracted. The spleens were ground into paste. The erythrocytes and other cells were lysed using distilled water and the T lymphocytes were collected. Monoclonal antibodies (CD3, CD4, CD8, CD25, IL-2, IFN-γ and TNF-α) were then added to the solution. The Facial Action Coding System was used to determine the positive rates of the cells combined with the monoclonal antibodies above. No significant statistical differences were observed between the CEN, NC and AG groups. However, some data of the FN group were significantly higher than those of the other groups at the corresponding time. No obvious immune rejections were observed among the chemically extracted acellular nerve allografts compared with fresh nerve autograft.

[Both the medial and lateral meniscal allograft transplantation following the anterior cruciate ligament reconstruction by arthroscopic surgical technique].

OBJECTIVE: To discuss the minimal invasive arthroscopic surgery technique and clinical results of both the medial and lateral meniscal transplantation following the anterior cruciate ligament reconstruction with double bundles and bone tunnels. METHODS: In August 2008 a minimal invasive surgery of both the medial and lateral meniscal allograft transplantation following anterior cruciate ligament reconstruction was preformed for 1 case with both the medial and lateral meniscectomy by arthroscopic surgery. The method of two bone plugs attached on tibial plateau was employed for medial meniscal allograft transplantation and the technique the bridge in slot for lateral meniscal allograft transplantation. The VAS, Lysholm score and IKDC rating were recorded before and after operation. The stability of knee was assessed by Lachman test, drawer sign and pivot shift test. RESULTS: The patient was followed up 26 month after the operations. The degrees of knee flexion, extension and function of walk were normal. The Lachman test, drawer sign and pivot shift test were nearly normal. The VAS after operation was 2 points lower than that before operation. The Lysholm score post-operation was 20 points higher than pre-operation. The IKDC became B degree in late following-up from C degree before the operation. MRI revealed anterior cruciate ligament graft was continuous and the meniscal allograft was normal shape on year 1 after the operation. The posterior horn of medial meniscal allograft and anterior corner of lateral meniscal allograft showed slightly shrunk. The second-look arthroscopy showed that the healing occurring between meniscal allograft and the capsule and meniscal allograft was normal shape on month 18 after the operation. The anterior horn of medial and lateral meniscus was slightly worn. CONCLUSIONS: Both the medial and lateral meniscal transplantation following the anterior cruciate ligament reconstruction in appropriately selected patients with the medial and lateral meniscus-deficient knee may recover the knee mechanic balance and stability, which is a option of treatment for that young and activity patients. It is proposed that the medial and lateral meniscal grafts harvested from a single donator. Attention should be paid to the direction of the bone tunnels fixing the horns of the meniscus in order to avoid communication with the tunnels of anterior cruciate ligament reconstruction.

Reconstructed bladder innervation below the level of spinal cord injury: the knee-tendon to bladder artificial reflex arc.

BACKGROUND/OBJECTIVE: To study the effectiveness of knee-tendon to bladder artificial reflex arc in dogs. METHODS: In 6 beagles, the proximal end of the right L5 anterior motor root and the distal end of the right S2 anterior root were anastomosed to build a knee-tendon to bladder reflex, whereas the right L5 posterior sensory root was kept intact. Action potential (AP) curves and electromyograms (EMGs) of the detrusor muscle, the intravesical pressure, horseradish peroxidase (HRP)-labeled neurons, and the passing rates of myelinic nerve fibers were calculated to evaluate its feasibility. RESULTS: AP curves and EMG detected in all 6 dogs were similar to those of the control. Six and 18 months after surgery, the means for bladder contraction induced by percussion of the right knee-tendon were 38 +/- 27% and 62 +/- 5% that of the normal control, respectively. The mean duration times induced by percussion of the right knee-tendon at 6 and 18 months after surgery were 51 +/- 37% and 84 +/- 12% that of the normal control, respectively. HRP retrograde tracing and neurohistologic observation indicated the feasibility of the artificial reflex arc. CONCLUSIONS: Our data showed the effectiveness of bladder innervation below the level of spinal cord injury producing urination by knee-tendon to bladder reflex contractions, and therefore, might provide a new clinical approach for restoring bladder function in individuals with paraplegia.

[Acellular nerve allograft by chemical extraction in humans].

OBJECTIVE: To develop a procedure by which Schwann cells and myelin in the peripheral nerve could be removed while the basal lamina tubes remained intact, and to obtain a thick and long acellular nerve allograft in humans. METHODS: Four ulnar nerves 10.0 cm long and 4.0 - 5.0 mm in diameter were excised from a donated male body and cleaned from external debris. The nerves were treated with a solution of Triton X-100 and a solution of sodium deoxycholate at room temperature. After a final wash in water, the nerves were stored in phosphate-buffered saline (PBS, pH 7.2) at 4 degrees C. HE, luxol fast blue and fibrin staining were performed to visualize cells, myelin and basal membranes respectively and immunohistochemical staining was performed to visualize the presence of laminin, a Schwann cell lamina component, both in fresh and acellular nerve segments. To reveal overall structure better, methylene blue-fuchsin staining was performed in semithin section. The ultrastructure of acellular and fresh nerves were observed and photographed in a transmission electron microscope. RESULTS: The acellular human ulnar nerve was white long cylinder with well elasticity and ductility. HE, myelin and fibrin staining revealed that cells, axons and myelin sheath were removed and basal membrane was preserved after extraction procedure. Staining for the presence of laminin showed that the Schwann cell basal lamina component were present in the nerves after chemical treatment. Methylene blue-fuchsin staining and transmission electron microscopy showed that the myelin sheaths were absent in the extracted nerve segments and empty basal lamina tubes remained in the endoneurium. CONCLUSIONS: We developed an extracted procedure with the detergents of Triton X-100 and deoxycholate, by which cells, axons and myelin sheaths could be removed from a human ulnar nerve while the basal lamina tubes remain intact and a thick long acellular nerve allograft is obtained. The laminin, a Schwann cell basal lamina component, can be preserved in the acellular nerve.