Neuromelanin-Sensitive MRI

Abstract   The basics and the technique of magnetic resonance imaging (MRI) for visualizing the neuromelanin present in dopaminergic and noradrenergic nuclei in the substantia nigra pars compacta (SNc) and locus caeruleus (LC) are introduced. Neuromelanin, a black pigment produced during catecholamine synthesis, has paramagnetic T1-shortening effects. Conventional MRI techniques fail to depict the contrast generated by neuromelanin, but neuromelanin-sensitive T1-weighted fast spin echo technique at 3 T allows the direct visualization of the SNc and LC as hyperintense areas. In Parkinson's disease, neuromelanin-related signals from the SNc and LC are diminished, suggesting neuronal degeneration in both the nuclei. In depression and schizophrenia, signals from the LC are reduced while those from the SNc are augmented, suggesting monoamine and dopamine hypotheses, respectively. Neuromelanin-sensitive MRI is a promising technique to elucidate the pathologic or functional changes in the catecholamine neurons of the brain stem that occur in degenerative and psychiatric diseases.      

Corrective osteotomy for malunited fracture of the glenoid cavity: a case report

Fractures of the glenoid cavity that are substantially displaced are rare. A patient with shoulder pain and dysfunction caused by a severely malunited fracture of the glenoid cavity was treated successfully with corrective osteotomy and bone grafting. Functional results 2 years after surgery were satisfactory, and radiographs showed no evidence of degenerative change. Although appropriate initial management should prevent the development of symptomatic malunion, results of the current study suggest that later reconstruction of the glenoid cavity restores satisfactory function, even if so much time has elapsed that glenoid osteotomy must be done to achieve reduction.     

The Use of Recipient Superficial Femoral Vein as a Venous Graft for Portal Vein Reconstruction in Right Lobe Living Donor Liver Transplantation

In living donor liver transplantation (LDLT), portal vein thrombosis (PVT) in the recipient is frequently regarded as a contraindication. To reconstruct the PV of a right-lobe liver graft (RLG) using an interposition or jump graft from the splenomesenteric junction, various vein grafts and technical modifications have been introduced. The internal jugular, external iliac, or great saphenous veins have been utilized in such reconstructive procedures. However, the superficial femoral vein (SFV) is preferable to the autologous vein grafts in terms of caliber, wall thickness, and length. We employed the recipient SFV to reconstruct PVT among 40 adult LDLT using RLG. Thirty-three were reconstructed by single end-to-end anastomosis with the right or left recipient PV. Three patients were transplanted with a RLG using 2 separated PVs reconstructed by double anastomoses with both the right and left PVs of the recipient. The remaining 4 patients required venous grafting for portal reconstruction. We used the recipient SFV as an interposition or jump graft from the splenomesenteric junction to the graft PV. There were 2 cases of anastomotic PV stenosis; 1 in portal reconstruction without a venous graft and the other with a SFV graft. Both were treated successfully by balloon angioplasty. The recipient SFV is an excellent size match for the PV reconstruction as a long interposition or jump conduit when the venous system from the deceased donor is not available. The indication for LDLT in patients with complete PVT should be carefully decided before transplantation in terms of portal reconstruction.     

Beneficial effect of FR183998, a Na+/H+ exchanger inhibitor, on porcine pancreas allotransplantation retrieved from non-heart-beating donors

Activation of Na(+)/H(+) exchanger (NHE) may have an important role in the ischemia/reperfusion injury by producing intracellular calcium overload. Recent studies have shown a beneficial effect of an NHE inhibitor on the ischemia/reperfusion injury in the heart. In this study, we examined the effect of FR183998, a potent NHE inhibitor, in porcine pancreas allotransplantation from non-heart-beating Landrace pig donors (NHBDs). The four experimental groups included: untreated with no preservation (group 1; n = 3), treated with no preservation (group 2; n = 5), untreated with preservation (group 3; n = 6), and treated with preservation (group 4; n = 4). The preservation was made in ice-cold University of Wisconsin (UW) solution for 24 hours. The groups treated received 1 mg/kg FR183998 before donor cardiac arrest and 10 mg in the UW solution flush in situ. Serum blood glucose, insulin, and amylase were measured daily. An intravenous glucose tolerance test (IVGTT) was performed on the postoperative day (POD) 7 when pigs were sacrificed for histological examination. Graft survival rates on that day in groups 1,2,3, and 4 were 3 of 3; 5 of 5; 3 of 6; and 4 of 4, respectively. The mean K values of IVGTT in groups 3 and 4 were 0.78 +/- 0.10 and 1.27 +/- 0.16, respectively, which were significantly different (P < .05). Upon histological examination, pancreatic tissue in group 3 showed more severe edema and necrosis than other groups. FR183998 may be considered beneficial for ischemia/reperfusion injury to pancreatic grafts from NHBDs.     

Drug-induced hypersensitivity syndrome due to mexiletine associated with human herpes virus 6 and cytomegalovirus reactivation

A 66-year-old man developed a fever of 38 degrees C and generalized pruritic rash about one month after mexiletine hydrochloride administration for ventricular tachycardia. The rash appeared as edematous erythema and papules with purpura on the lower extremities. Liver dysfunction, leukocytosis, and atypical lymphocytes were also present. Elevated antibody titer against human herpes virus 6 (HHV-6) was detected during the course of the disease (1:20 -> 1:640). The patient was diagnosed as having drug-induced hypersensitivity syndrome (DIHS) due to mexiletine. Discontinuation of the mexiletine administration and systemic corticosteroid treatment led to a temporary improvement, but tapering the corticosteroid dose twice led to recrudescence. Simultaneous with the recrudescence, elevated antibody titers against HHV-6 and cytomegalovirus were detected, as well as viral DNA in the blood, suggesting that these two viruses may have been involved in the recrudescence. The patient died of myocarditis, most likely related to cytomegalovirus. Our case indicates that, in addition to HHV-6, other herpes viruses such as cytomegalovirus can be reactivated in DIHS and may modify the clinical disease activity.     

Epithelial cell density in cataractous lenses of patients with diabetes: association with erythrocyte aldose reductase

In the present study we evaluated the cell density of lens epithelium and its relation to the degree of erythrocyte aldose reductase (AR) in patients with type 2 diabetes. This prospective clinical study included 46 eyes of patients with type 2 diabetes and 48 eyes of patients without diabetes mellitus (DM). Flat preparations of lens epithelial cells (LECs) attached to the anterior capsule were studied. Multiple regression analysis was performed to evaluate the association between lens cell density and age, gender, type of cataract, duration of diabetes, diabetic retinopathy (DR), the levels of glycosylated hemoglobin (HbA1c) and erythrocyte AR. The mean density of LECs of patients with type 2 diabetes was 4,141+/-508cells/mm(2), which was significantly lower than that of patients without DM (4,560+/-458cells/mm(2); p<0.0001). Multiple regression analysis revealed that the level of erythrocyte AR was correlated with the reduction of LECs in the eyes of patients with type 2 diabetes. The correlation between the density of LECs and the amount of erythrocyte AR was significant in the diabetic group with a high value of HbA1c (>6.5%) or with DR. These results suggest that the polyol pathway via AR may be associated with the reduction of epithelial cell density in the eyes of patients with DM.     

Genomic structure around joining segments and constant regions of swine T-cell receptor alpha/delta (TRA/TRD) locus

A complete genomic region of 131.2 kb including the swine T-cell receptor alpha/delta constant region (TRAC/TRDC) and joining segments (TRAJ/TRDJ) was sequenced. The structure of this region was strikingly conserved in comparison to that of human or mouse. All of the 61 TRAJ segments detected in the human genomic sequence were detected in the swine sequence and the sequence of the protein binding site of T early alpha, the sequence of the alpha enhancer element and the conserved sequence block between TRAJ3 and TRAJ4 are highly conserved. Insertion of the repetitive sequences that interspersed after the differentiation of the species in mammals such as short interspersed nucleotide elements is markedly suppressed in comparison to other genomic regions, while the composition of the mammalian-wide interspersed sequences is relatively conserved in human and swine. This observation indicates the existence of a highly selective pressure to conserve this genomic region around TRAJ throughout the evolution of mammals.     

Metabolic cardiovascular disease risk factors and their clustering in subclinical hypothyroidism

Objective A possible association between subclinical hypothyroidism and cardiovascular disease (CVD) has been reported. Monitoring of atomic‐bomb survivors for late effects of radiation exposure at the Radiation Effects Research Foundation has provided the opportunity to examine associations between subclinical hypothyroidism and metabolic CVD risk factors. The objective of the study was to evaluate associations between subclinical hypothyroidism and metabolic CVD risk factors, and a cluster of these factors. Design and participants This was a cross‐sectional study of 3549 subjects (mean age 70 years; 1221 men and 2328 women) between 2000 and 2003 comprising 306 subjects with subclinical hypothyroidism and 3243 control euthyroid subjects in Japan. Measurements We investigated associations between subclinical hypothyroidism and metabolic CVD risk factors such as hypertension, diabetes mellitus, dyslipidaemia and hyperuricaemia, and a cluster of these factors. Results Subclinical hypothyroidism was not significantly associated with either hypertension, diabetes mellitus or hyperuricaemia defined by taking into account the use of medications in both men and women, but in men it was associated with dyslipidaemia (P = 0·02). We observed a significantly increased odds ratio (OR) for the presence of three or more metabolic CVD risk factors in men with subclinical hypothyroidism after adjusting for age, body mass index (BMI), and smoking status [OR: 1·83, 95% confidence interval (CI): 1·13–2·94, P = 0·01]. The significant associations remained after an additional adjustment for atomic‐bomb radiation dose. Conclusions There appears to be a significant increase in a cluster of metabolic CVD risk factors among people with subclinical hypothyroidism.     

Uptake of dehydroascorbic acid in high-GSH and normal-GSH dog erythrocytes

Uptake of dehydroascorbic acid (DHA) was studied in two types of dog erythrocytes with high GSH and normal GSH levels. Compared with ascorbic acid uptake, DHA produced a much greater ascorbic acid accumulation in dog erythrocytes. Both dog erythrocytes showed a concentration dependence of DHA uptake, and cellular ascorbic acid concentrations were significantly higher in high-GSH cells than in normal-GSH cells. Glucose and cytochalasin B inhibited DHA uptake. This suggests that DHA enters dog erythrocytes predominantly by the facilitated glucose transporter, particularly by the Glut 1 glucose transporter. The rate of glucose uptake was quite similar in the two types of cells. Compared with normal-GSH cells, high-GSH cells were more resistant to oxidative stress induced by high concentration of DHA. As a rapid entry of DHA inflicts on cells a heavy demand for GSH for its reduction to ascorbic acid, high-GSH cells containing a larger reserve of GSH have an advantage over normal-GSH cells in both ascorbic acid accumulation and resisting oxidative stress produced by DHA.