Role of Helix 8 in Dopamine Receptor Signaling

G protein-coupled receptors (GPCRs) are membrane receptors whose agonist-induced dynamic conformational changes trigger heterotrimeric G protein activation, followed by GRK-mediated phosphorylation and arrestin-mediated desensitization. Cytosolic regions of GPCRs have been studied extensively because they are direct contact sites with G proteins, GRKs, and arrestins. Among various cytosolic regions, the role of helix 8 is least understood, although a few studies have suggested that it is involved in G protein activation, receptor localization, and/or internalization. In the present study, we investigated the role of helix 8 in dopamine receptor signaling focusing on dopamine D1 receptor (D1R) and dopamine D2 receptor (D2R). D1R couples exclusively to Gs, whereas D2R couples exclusively to Gi. Bioinformatic analysis implied that the sequences of helix 8 may affect GPCR-G protein coupling selectivity; therefore, we evaluated if swapping helix 8 between D1R and D2R changed G protein selectivity. Our results suggest that helix 8 is not involved in D1R-Gs or D2R-Gi coupling selectivity. Instead, we observed that D1R with D2R helix 8 or D1R with an increased number of hydrophobic residues in helix 8 relative to wild-type showed diminished β-arrestin-mediated desensitization, resulting in increased Gs signaling.

Result of Treatment of Open Tibial Fracture with Hoffmann External Fixator / 대한정형외과학회잡지

Recently, tibial shaft fractures become more severe because of high speed traffic accidents. The open tibial fracture is a difficult one to treat because of its common complications such as infection, soft tissue defect, delayed union and non-union. We studied 37 cases of open tibial fractures which were treated with external fixation. The results are as follows: 1. The average patient age was 29.3 years and male predominated by a ratio of 4.3: l. 2. The traffic accidents were the most common cause of injury. 3. Most cases(67.6%) were type III fracture(by classification of Gustilo and Anderson). 4. Hoffmann external fixator gave rigid fixation and good wound access. 5. There were 28 cases(75.7%) which needed secondary soft tissue reconstruction. 6. The infection rate was 21.5%(8 cases). These all healed with conservative management. There were 5 cases of pin tract infection which healed without developing osteitis. 7. The average union time was 28.7 weeks. In type III fracture there was marked delay in union (average 32.1 weeks). 8. The rate of development of delayed or non-union was 35.1%. In these cases, bony union was obtained with cancellous bone graft.

Clinical Study of Diabetic Foot / 대한정형외과학회잡지

The incidence of diabetes mellitus is in increasing tendency because of expension of medical care, economic development and increasing of the population of the aged person recently. The diabetic foot is one of serious complication of diabetes. With the advancement of the method of treatment of diabetes the other acute metabolic complications are decreased, but the development of diabetic gangrene encounteres at any age of adult life with increasing of incidence according to the duration of diabetes. The most of them requires operation, and its treatment is difficult frequently because of high incidence of wound problem in healing. So it is important to educate and prevent for lowering its incidence. From January 1978 to December 1984, 38 patients with diabetic foot were treated and analysed at Department of Orthopaedic Surgery of Presbyterian Medical Center. The results obtained are as follow. 1. The average of annual incidence of diabetic gangrene was 2.85%. There was increasing tendency of incidence to 1981, thereafter decreasing tendency. 2. 71% of patients with gangrene were in over-50 year age group. 3.72% of patients were in duration of diabetes more than 5 years. 4.79% of patiens were in inadequate treatment before admisson. 5. There was no relationship between fasting blood sugar level and development of gangrence. 6. The most common site of the lesion was big toe. 7. The most common predisposing fector was local pressure (39%), then minor trauma, and burn injury. 8. The primary wound healing rate was 53% after operation. 9. There was no relationship between the lowest palpable artery and primary wound healing. 10. The most common combined complication of diabetes was retinopathy (47%), then neuropathy and hypertension. 11. The rate of bacterial infection was 66%, and the most common organism was staphylococcus aureus (36%).

Ehlers-Danlos Syndrome: 2 Cases Report / 대한정형외과학회잡지

The Ehlers-Danlos syndrome is a familial disorder of connective tissue, and seven distinct clinical forms are reported. Author experienced two cases of the type 3 Ehlers-Danlos syndrome which present hypermobility of the joints, asymmetry of the thorax, anomalies of the thoracic spine, and flatfoot. So, we report these patients with references.

Poland's Syndrome: A Case Report / 대한정형외과학회잡지

Poland's syndrome is congenital anomaly which was described first by Alfred Poland in 1841. The clinical features are variable but always include congenital aplasia of fingers and syndactyly. We have experienced a case of Poland's syndrome. This case was male children and revealed thoracic anomaly of right side (absence of pectoral muscles and anterior axillary fold), atrophy of forearm muscles, ipsilateral syndactyly with aplasia of thumb and middle phalanges of 2, 3, 4, 5,th fingers, and ipsilateral congenital radio-ulnar synostosis.

A Clinical Study on Ligamentous Injuries of the Knee / 대한정형외과학회잡지

The function of the knee joint is determined by the anatomical integrity of ligamentous structures, however the ligaments and soft tissues which support by the knee joint are too weak to tolerate forceful stresses. The knee joint is one of the most susceptible joints to ligamentous injury. Recently, the incidence of ligamentous injuries of the knee increased because of rise in traffic accidents and participation in sports. For good results, it is very important to make an early diagnosis and to give prompt management. The authors reviewed 67 cases of ligamentous injuries in patients who were admitted and managed at the Department of Orthopaedic Surgery of Presbyterian Medical Center from March of 1976 to December of 1982. The results of the clinical study are as follows: 1. The prevalent age group is the 3rd through 5th decades, and more frequent in males (8. 6 times). 2. The traffic accident is the most common cause of injury (80. 6%) and many ligamentous injuries were associated with fracture (53. 2%). 3. The most common ruptured individual ligament was the medial collateral ligament. The isolated ligamentous rupture of anterior and posterior cruciate ligament was 3 cases each, but most of the cruciate ligaments were combined with other ligament injury. 4. The rupture sites of the individual ligaments were found to be the following: (a) The medial collateral ligament was ruptured most frequently in the mid-substance (45. 2%), with the deep layer ruptured at the femoral attachment and the superficial layer in the mid-substance; (b) The lateral collateral ligament torn at the fibular attachment (62. 5%); (c) The anterior cruciate ligament torn at the femoral and tibial (47. 6%, respectively); (d) The posterior cruciate ligament torn at the femoral attachment (40. 0%). 5. It is significant if the difference between the normal knee and the injured knee on the stress film is more than 10 or 10mm. 6. Excellent and good results were obtained in 95.2% by non-surgical management and in 93.0% by surgical management. 7. Early surgical repairs, made within 2 weeks after injury, gave much better results than late repairs.