Changes in the T2 relaxation value of the tibiofemoral articular cartilage about 6 months after anterior cruciate ligament reconstruction using the double-bundle technique.

OBJECTIVE: To evaluate T2 relaxation values (T2RVs) of knee joint cartilage after double-bundle anterior cruciate ligament reconstruction (DB-ACLR) in a 6-month follow-up and to correlate changes between T2RVs with meniscal status and clinical findings. METHODS: 27 patients who underwent DB-ACLR and MRI before and 6 months after surgery, and 27 control subjects were enrolled. We compared T2RVs of the control vs pre-operative MR and pre-operative vs post-operative MR using 28 subcompartments, including superficial and deep layers. Correlations between T2RV changes with meniscal status and clinical data were examined. RESULTS: The pre-operative T2RV was significantly higher than that of the control group in the medial tibia (posterior-superficial), posterior medial femur (superficial) and posterior lateral femur (superficial and deep). The post-operative T2RV was significantly higher than that of pre-operative T2RV in the posterior medial femur (superficial), medial tibia (anterior-deep and central-deep), lateral femur (anterior-deep, anterior-superficial and central-superficial) and posterior medial femur (deep). Moderate positive correlations between pre-operative and post-operative T2RV changes were found at the posterior medial femur (interval between injury and MR examination, and instability) and posterior lateral femur (Lysholm score). CONCLUSION: Patients with anterior cruciate ligament injury followed by DB-ACLR presented short-term subcompartment T2RV changes at the medial femur, lateral femur and medial tibia. Meniscal status did not affect T2RV; however, clinical findings influenced T2RV at the posterior grooves of the medial and lateral femoral condyles. ADVANCES IN KNOWLEDGE: Patients submitted to DB-ACLR presented T2RV changes in both femoral and medial tibial condyles 6 months after the surgery, affecting not just the weight-bearing areas, but also the less-weight-bearing areas.

Generation and characterization of human hybrid neurons produced between embryonic CNS neurons and neuroblastoma cells.

A human hybrid neuronal cell line A1 has been generated by somatic fusion between a human fetal cerebral neuron and a human neuroblastoma cell, and RT-PCR, immunochemical, and electrophysiological studies of the hybrid cells indicated that the cells express faithfully of morphological, immunochemical, physiological, and genetic features of human cerebral neurons. A1 hybrid neurons express neuron-specific markers such as neurofilament-L (NF-L), NF-M, NF-H, MAP-2, and beta tubulin III. A1 human hybrid neurons express messages for various cytokines and cytokine receptors which are similar to parental human CNS neurons and different from the other parental cell line, SK-SH-SY5Y neuroblastoma. A1 hybrid neurons also express messages for choline acetyltransferase (ChAT), tyrosine hydroxylase (TH), and glutamic acid decarboxylase (GAD), indicating that they could differentiate into various subsets of neuronal types. Whole-cell patch clamp experiments showed that A1 hybrid neurons expressed Na+ currents, which were completely blocked by tetrodotoxin. In addition, depolarizing and hyperpolarizing voltage clamp steps evoked respective outward and inward K+ currents in these cells. When A1 hybrid neurons were exposed to beta amyloid for 72 hr, there was three-fold increase in TUNEL positive cells over controls, indicating that beta amyloid is neurotoxic to A1 hybrid neurons. The present study indicates that the A1 human hybrid neuronal cell line should serve as a valuable in vitro model for studies of biology, physiology, and pathology of human neurons in health and disease.