P599Native T1 mapping is useful for detection of myocardial fibrosis in cases with ischemic and non-ischemic myocardial diseases

Background

Evaluation of myocardial fibrosis (MF) as late gadolinium enhancement (LGE) on MRI is useful for differential diagnosis of various myocardial diseases and prediction of future adverse cardiac events in some specific myocardial diseases. Gadolinium contrast is contraindicated for cases with severe renal dysfunction, therefore non contrast MRI is necessary for detection of MF in cases with both myocardial disease and severe renal dysfunction.

Purpose

We aimed to evaluate diagnostic accuracy of native T1 mapping for detection of MF compared with LGE in cases with various myocardial diseases, including ischemic and non-ischemic myocardial diseases.

Methods

We selected consecutive 40 patients who were suspected of having various myocardial diseases and underwent cardiac MRI, using 1.5T MRI (Ingenia, Philips) in 10 cases (25%) or 3T MRI (Ingenia, Philips) in 30 cases (75%), including native T1 mapping (without contrast) and LGE using contrast media from Jan 2018 to Feb 2019 in our institution. We evaluated diagnostic accuracy for detection of MF in left ventricular myocardium (LVM) of native T1 mapping image compared with LGE as the gold standard, in a patient-based and segment-based analysis. In T1 mapping images, segmental high T1 lesions were defined as MF. In a segment-based analysis, MF was evaluated using 17 LVM segments model in American Heart Association.

Results

MF was detected in 139 LVM segments in 25 (63%) cases. Sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of native T1 mapping for detection of MF were 90%, 89%, 95%, 80% and 90% in a patient-based analysis, and 63%, 96%, 84%, 89% and 88% in a segment-based analysis (left figure). Native T1-values of LVM with MF were significantly higher than LVM without LGE (1351±79 vs 1093±124 in 1.5T and 1562±131 vs 1291±43 in 3T) (p<0.05 and p<0.01). Interobserver agreement of native T1 mapping and LGE were not significantly different (0.88 and 0.89, P=0.70). Overall diagnostic accuracy of native T1 mapping for detection of MF in a patient-based analysis, was not significantly different in between the cases with ischemic (n=18) and non-ischemic (n=22) myocardial disease (90% and 83.3%, P=0.10).

Conclusion

Native T1 mapping (without contrast) is useful for detection of MF in various myocardial diseases and high diagnostic accuracy is expected especially in a patient-based analysis.

P6182Combination of a new iterative reconstruction technique with low tube voltage and high tube current has important role of detection of late enhancement on 320 slice CT

Background

New iterative reconstruction tecniques, including Adaptive Iterative Dose Reduction 3D (AIDR 3D) and Forward Projected Model-based Iterative Reconstruction SoluTion (FIRST), have been recently available on new generation 320 slice CT, and they can provide high-quality CT images.

Purpose

The aim of this study was to evaluate the diagnostic performance of detection of abnormal late enhancement (LE) in left ventricular (LV) myocardium (LVM) using 320-slice CT with new iterative reconstruction techiniques, AIDR 3D (Figure A) and FIRST (Figure B).

Methods

A total of 100 patients who were suspected of having various myocardial diseases and underwent late phase acquisition both on cardiac CT and CMR within 3 months were analyzed. The first 50 consecutive patients (Group 1) underwent 320-slice CT with AIDR 3D, 120 Kv tube voltage, 519±71 mA tube current. The next 50 consecutive patients (Group 2) underwent 320-slice CT with FIRST, 80 or 100Kv tube voltage, 803±20 mA tube current. We compared diagnostic accuracy of CT for detection of LE in LVM against that of CMR (the gold standard) in between the 2 groups.

Results

On patient-by-patient analysis, sensitivity, specificity, positive (PPV) and negative predictive values (NPV), and overall accuracy for detection of LE on CT vs CMR were 87, 95, 96, 82, and 90% in Group 1, and 97, 83, 91, 88, and 90% in Group 2. There were no significant difference of diagnostic accuracy on patient-by-patient analysis in between the 2 groups (Figure C). However, on a segment-by-segment analysis (using 17 American Heart Association LV segment model), these values for detection of LE on CT vs CMR were 60, 95, 73, 91, and 88% in Group 1, and 85, 95, 86, 95, and 93% in Group 2. Sensitivity, PPV, NPV and overall accuracy were significantly higher in Group 2 than in Group 1 (all P<0.01) (Figure D).

Conclusions

Diagnostic accuracy of detection of LE in LVM on CT combining low tube voltage and high tube current acquisition on a new generation 320-slice CT with FIRST was superior to 320-slice CT with AIDR 3D.

Acknowledgement/Funding

TSUCHIYA MEMORIAL MEDICAL FOUNDATION

Identification and Genetic Analysis of a Common Molecular Variant of Histidine-rich Glycoprotein with a Difference of 2KD in Apparent Molecular Weight

Two forms of histidine-rich glycoprotein (HRG) were detected on SDS-PAGE by silver staining and immunoblotting after isolation of the protein from pooled plasma using immuno-affinity chromatography followed by chromatography with heparin-Sepharose. Both forms were single-chain molecules and the apparent molecular weights of form 1 and form 2 were 77 kD and 75 kD respectively. Mendelian inheritance of both HRG forms was observed in four families with 24 informative meioses, strongly suggesting that the two forms are encoded by different alleles. The frequency of form 1 and form 2 in a group of 36 individuals was 0.35 and 0.65 respectively.

The difference between the two molecular variants was studied by direct sequence analysis of amplified exons of the HRG gene from 6 individuals who were homozygous either for form 1 or form 2. Five amino acid polymorphisms in three different exons were observed: Ile/Thr in exon 4; Pro/Ser in exon 5; His/Arg, Arg/Cys and Asn/Ile in exon 7. Analysis of these polymorphisms in 20 volunteers showed that only the Pro/Ser polymorphism at position 186 in exon 5 was coupled to the form of the HRG protein. Ser was found in form 1 and Pro in form 2. The presence of Ser at position 186 introduces a consensus sequence for a N-glycosylation site (Asn-X-Ser/Thr). By removing N-linked sugars with N-glycanase, it could be demonstrated that the difference between the two forms of HRG is caused by an extra carbohydrate group at Asn 184 in form 1.

Reconstruction of the Shallow Acetabulum With a Combination of Autologous Bulk and Impaction Bone Grafting Fixed by Cement

BACKGROUND

Acetabular bone deficiency, especially proximal and lateral deficiency, is a difficult technical problem during primary total hip arthroplasty (THA) in developmental dysplasia of the hip (DDH). We report a new reconstruction method using a medial-reduced cemented socket and additional bulk bone in conjunction with impaction morselized bone grafting (additional bulk bone grafting method).

QUESTIONS/PURPOSES

In a population of patients with acetabular dysplasia undergoing THA using a medial-reduced cemented socket and additional bulk bone with impacted morselized bone grafting, we evaluated (1) the radiographic appearance of bone graft; (2) the proportion of cups that developed loosening and subsequent revision; and (3) clinical results (outcome scores and complications).

METHODS

Forty percent of 330 THAs for DDH performed at one center between 1999 and 2009 were defined as shallow dysplastic hips. The additional bulk bone grafting method was performed on 102 THAs with shallow acetabulum (31% for DDH) at one center between 1999 and 2009. We used this approach and technique for shallow acetabuli when a cup protruded from the lateral acetabular edge in preoperative templating. The other 132 dysplastic hips without bone grafting had THA performed at the same periods and served as a control. Acetabuli were defined as shallow when the depth was less than or equal to one-fifth of the pelvic height (cranial-caudal length on radiograph). The additional bulk bone grafting technique was as follows: the resected femoral head was sectioned at 1 to 2 cm thickness, and a suitable size of the bulk bone graft was placed on the lateral iliac cortex and fixed by poly-L-lactate absorbable screws. Autologous impaction morselized bone grafting, with or without hydroxyapatite granules, was performed along with the implantation of a medial-reduced cemented socket. We defined an "incorporated" graft as remodeling and trabeculation including rounding off of the protruding edge of a graft beyond the socket. Radiographic criteria used for determining loosening were migration or a continuous radiolucent zone between the prosthesis/bone cement and host bone. Clinical outcomes were assessed using the Japanese Orthopaedic Association (JOA) and the Merle d'Aubigne and Postel score; complications were tallied from chart review. The followup was 10 ± 3 years (range, 6-15 years).

RESULTS

One acetabular component (1%) with severe shallow and steep acetabuli showed definite radiographic evidence of loosening and was revised. Clinically, the mean JOA score for the hips treated with additional bulk bone grafting THA in this study improved from 39 ± 10 points preoperatively to 95 ± 5 points postoperatively (p < 0.05, paired t-test). The mean Merle d'Aubigne and Postel score for the hips improved from 7 ± 2 points to 17 ± 1 points (p < 0.05, paired t-test). Complications included a Trendelenburg sign in one hip, dislocation in one, and transient partial sciatic nerve palsy in one. Within 3 years 6 months postoperatively, 101 of 102 additional bulk bone grafting cases showed successful bone remodeling and bone graft reorientation without collapse on radiographs. Partial resorption of the additional bone graft on the lateral side was observed in two hips (2%) with socket abduction angles of < 35°.

CONCLUSIONS

Achieving stable acetabular fixation is often challenging in the dysplastic hip, especially shallow acetabulum, and a variety of techniques have been described. Early results of combining bulk graft with impaction of morselized graft are promising. Although each surgical technique was well established, further investigation for clinical results of a combination of these techniques might be necessary to confirm longer term outcomes.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Movement Patterns as an Output Variable in Reaction Time

Effects of two experimental variables, movement pattern and signal selection, on EMG-reaction time (RT) of the biceps brachii were investigated in 17 subjects. Analysis showed that (a) interaction of two variables was not significant in the analysis of variance, (b) RT-difference between the movement patterns was not affected by the signal selection, and (c) the degree of EMG-RT slowing due to the process of signal selection did not vary with movement patterns. The movement pattern was regarded as an output variable.

Less invasive rotational acetabular osteotomy for hip dysplasia

BACKGROUND

Broad dissection with a long skin incision and detachment of the gluteus medius muscle performed for rotational acetabular osteotomy (RAO) can result in weakness in abduction strength of the hip. We use a surgical procedure for RAO that minimizes operative invasion of soft tissue and reduces incision length compared with conventional procedures.

QUESTIONS/PURPOSES

We evaluated the clinical results of this less-invasive RAO comparing it with the more-invasive prior procedure with respect to improvement in clinical hip scores and radiographic coverage and overall hip survival after the procedure.

METHODS

In this less-invasive exposure, the medial gluteus muscle is retracted to expose the ilium without detachment from the iliac crest. Similarly, the rectus femoris muscle tendon is retracted, not excised. The lateral part of the osteotomized ilium is cut to form the bone graft instead of harvesting it from the outer cortical bone of the ilium. Between 2000 and 2009, 62 patients (71 hips) underwent this procedure. Twenty-eight hips had early-stage osteoarthritis and 43 had advanced-stage osteoarthritis. Mean patient age was 40 years at the time of surgery. We evaluated improvement in hip scores (Merle d'Aubigné-Postel, Japanese Orthopaedic Association) and radiographic appearance (lateral center-edge angle, Sharp's angle, acetabular head index [AHI]). Kaplan-Meier survivorship analysis was performed. Mean followup was 5 years (range, 2.0-10.4 years).

RESULTS

Clinical hip scores improved postoperatively. On average, lateral center-edge angle, Sharp's angle, and AHI improved by 38°, 11°, and 42%, respectively. Predicted 10-year survival rates were 100% and 72% for hips with early- and advanced-stage osteoarthritis, respectively.

CONCLUSIONS

In hips with early-stage osteoarthritis treated by this less-invasive approach, no progression of osteoarthritis was documented and Trendelenburg gait was avoided. However, further investigation is necessary for hips with advanced-stage osteoarthritis.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

The effect of a prostaglandin E1 derivative on the symptoms and quality of life of patients with lumbar spinal stenosis

BACKGROUND

Quality of life (QOL) is a concern for patients with lumbar spinal stenosis (LSS). In this study, QOL was examined using the 5-item EuroQol (EQ-5D).

METHODS

QOL and activities of daily living (ADL) were surveyed for 91 patients who visited 18 medical institutions in our prefecture and were diagnosed with LSS-associated intermittent claudication. A second survey was performed after ≥6 weeks for 79 of the subjects to evaluate therapy with limaprost (an oral prostaglandin E1 derivative) or etodolac (an NSAID). Symptoms, maximum walking time, QOL, ADL items, and relationships among these variables were investigated for all 91 patients. Leg pain, leg numbness, and low back pain while walking were surveyed by use of VAS scores (0-100).

RESULTS

Leg pain, leg numbness, and low back pain while walking (VAS ≥25) were present in 83.5, 62.6, and 54.9 % of the patients in the first survey, and approximately half of the patients had a maximum walking time <15 min. The mean EQ-5D utility value for QOL was 0.59 ± 0.12. This value was significantly associated with maximum walking time (p = 0.030) based on classification of patients into groups with walking times <7.5, 7.5-15, 15-30, and >30 min, showing that maximum walking time affected health-related QOL. Of the 79 patients who completed the second survey, 56 had taken limaprost and 23 (control group) had received etodolac. Limaprost improved possible walking time, reduced ADL interference, and significantly increased the EQ-5D utility score, whereas no significant changes occurred in the control group. Maximum walking time was prolonged by ≥10 min and the EQ-5D utility value was improved by ≥0.1 points in significantly more patients in the limaprost group than in the control group.

CONCLUSION

According to the findings of this survey, at an average of 8 weeks after administration limaprost improved symptoms, QOL, and ADL in LSS patients whereas treatment with an NSAID reduced pain but did not have any other effects.

Hydroxyapatite block for reconstruction of severe dysplasia or acetabular bone defects in total hip arthroplasty: operative technique and clinical outcome

Fourteen hips in 14 patients (all female; average age, 64 years) with severe bone defects due to developmental dysplasia of the hip or migration of the socket were treated with hydroxyapatite block with impacted morselized bone graft in conjunction with a cemented socket. All patients were followed clinically in a prospective fashion, and radiographs were analyzed retrospectively. One initial patient had 17-year follow-up, whereas the remaining 13 patients had follow-up between 4 and 6.5 years. No acetabular components were revised, including the socket of a 17-year postoperative case that remains rigidly fixed and supported by the graft and hydroxyapatite block with only mild polyethylene wear and minor osteolysis. Osteointegration and good clinical outcome were achieved in all cases by reconstruction with this technique in total hip arthroplasty.

Elevation of serum high molecular weight adiponectin in patients with Type 2 diabetes and orthostatic hypotension: association with arterial stiffness and hypercoagulability

AIM

Orthostatic hypotension is a hallmark of diabetic autonomic neuropathy and is associated with increased mortality. The serum level of adiponectin is elevated in patients with heart failure or renal failure. In the present study, we measured serum levels of total and high molecular weight adiponectin in patients with Type 2 diabetes and orthostatic hypotension. We also investigated the relationship between the presence of orthostatic hypotension and various clinical variables in patients with Type 2 diabetes.

METHODS

We studied 105 patients with Type 2 diabetes. Orthostatic hypotension was defined as a decrease of 20 mmHg or more in systolic blood pressure and/or 10 mmHg in diastolic blood pressure when blood pressure was measured for 3 min while standing. The brachial-ankle pulse-wave velocity was also measured as an index of arterial stiffness.

RESULTS

Orthostatic hypotension was found in 30 patients with diabetes (28.6%). The haematocrit and estimated glomerular filtration rate were significantly lower in patients with orthostatic hypotension than in those without it. Brachial-ankle pulse-wave velocity and serum total and high molecular weight adiponectin were significantly higher in patients with orthostatic hypotension than in those without. Furthermore, the high molecular weight/total adiponectin ratio was higher in patients with orthostatic hypotension than in those without and hypertension was more common in patients with orthostatic hypotension. Plasma prothrombin F1 + 2, a coagulation maker, was higher in patients with orthostatic hypotension than in those without, while there were no differences of fibrinolytic markers between the two groups. Multivariate analysis showed that HDL cholesterol, haematocrit, F1 + 2, brachial-ankle pulse-wave velocity and a decline of systolic blood pressure on standing were independent determinants of high molecular weight adiponectin.

CONCLUSIONS

Patients with Type 2 diabetes and orthostatic hypotension had an elevated serum level of high molecular weight adiponectin, which was associated with the simultaneous presence of renal dysfunction, anaemia, arterial stiffness and hypercoagulability.

Positional relationship between recurrent intracerebral hemorrhage/lacunar infarction and previously detected microbleeds

BACKGROUND AND PURPOSE

Although MBs, ICH, and LI are secondary to cerebral microangiopathy, it remains unclear whether the location of subsequent ICH/LI corresponds to the previous location of MBs. We performed this study to clarify the positional relationship between recurrent ICH/LI and previously detected MBs.

MATERIALS AND METHODS

We evaluated patients with recurrent ICH/LI who had MBs, as shown on prior T2*-weighted MR imaging. We assessed retrospectively whether the location of recurrent ICH/LI corresponded to that of the prior MB. Patients with ICH were divided into the deep ICH group and the lobar ICH group, and the positional relationship between hematoma and previously detected MBs was evaluated.

RESULTS

A total of 55 patients, including 34 with recurrent ICH and 21 with recurrent LI were evaluated. Although the location of the LI corresponded to prior MBs in only 1 patient (4.8%), the location of ICH corresponded to prior locations of MBs in 21 patients (61.8%) (OR, 32.3; 95% CI, 3.86-270.3; P < .001). Among the patients with ICH, the correspondence ratio was higher in the deep ICH group (19 of 24 patients, 79.2%) than in the lobar ICH group (2 of 10 patients, 20%) (OR, 15.2; 95% CI, 2.42-95.3; P < .002).

CONCLUSIONS

The close positional association between recurrent ICH and prior MBs suggests that MBs represent hemorrhage-prone microangiopathy. In addition, different correspondence ratios between the deep ICH group and the lobar ICH group may be attributable to their different pathogenesis.

Association between cerebral microbleeds on T2*-weighted MR images and recurrent hemorrhagic stroke in patients treated with warfarin following ischemic stroke

BACKGROUND AND PURPOSE

Although accumulating evidence suggests the presence of microbleeds as a risk factor for intracerebral hemorrhage (ICH), little is known about its significance in anticoagulated patients. The aim of this study was to determine whether the presence of microbleeds is associated with recurrent hemorrhagic stroke in patients who had received warfarin following atrial fibrillation-associated cardioembolic infarction.

MATERIALS AND METHODS

A total of 87 consecutive patients with acute recurrent stroke, including 15 patients with ICH and 72 patients with cerebral infarction, were enrolled in this study. International normalized ratios (INRs), vascular risk factors, and imaging characteristics, including microbleeds on T2*-weighted MR images and white matter hyperintensity (WMH) on T2-weighted MR images, were compared in the 2 groups.

RESULTS

Microbleeds were noted more frequently in patients with ICH than in patients with cerebral infarction (86.7% versus 38.9%, P = .0007). The number of microbleeds was larger in patients with ICH than in patients with cerebral infarction (mean, 8.4 versus 2.1; P = .0001). INR was higher in patients with ICH than in patients with cerebral infarction (mean, 2.2 versus 1.4; P < .0001). The frequency of hypertension was higher in patients with ICH than in patients with cerebral infarction (86.7% versus 45.8%, P = .0039). Multivariate analysis revealed that the presence of cerebral microbleeds (odds ratio, 7.383; 95% confidence interval, 1.052-51.830) was associated with ICH independent of increased INR and hypertension.

CONCLUSION

The presence of cerebral microbleeds may be an independent risk factor for warfarin-related ICH, but more study is needed because of strong confounding associations with elevated INR and hypertension.

Comparison of the effects of pioglitazone and voglibose on circulating total and high-molecular-weight adiponectin, and on two fibrinolysis inhibitors, in patients with Type 2 diabetes

BACKGROUND

To investigate short-term effects of pioglitazone and voglibose on serum concentrations of both total and high-molecular-weight (HMW) adiponectin measured with a novel sandwich enzyme-linked immunosorbent assay (ELISA) ,and on plasma fibrinolysis indicators, in Type 2 diabetic patients with inadequate glycaemic control on sulphonylureas.

METHODS

Thirty-four diabetic patients were randomized to receive pioglitazone or voglibose treatment for 12 weeks, after which serum HMW adiponectin was measured. Plasma plasminogen activator inhibitor (PAI) 1 and thrombin-activatable fibrinolysis inhibitor (TAFI), a recently identified inhibitor of fibrinolysis, were measured as fibrinolysis inhibitors.

RESULTS

At baseline, serum HMW adiponectin correlated negatively with plasma TAFI in all patients with Type 2 diabetes (r = -0.367, P = 0.0423). Both groups showed similar improvements in glycaemic control. Serum total and HMW adiponectin increased in patients treated with pioglitazone, but did not change in patients treated with voglibose. The HMW : total adiponectin ratio increased significantly after treatment with pioglitazone (P = 0.0004). The change in HbA(1c) correlated negatively with changes in serum HMW adiponectin in patients treated with pioglitazone (r = -0.694, P = 0.0034). Plasma PAI-1 and TAFI did not change with pioglitazone treatment.

CONCLUSION

Increased serum HMW adiponectin may contribute to the improvement in glycaemic control after pioglitazone treatment. Plasma PAI-1 and TAFI were unchanged by either drug.

Purification of branched-chain amino acid aminotransferase from Helicobacter pylori NCTC 11637

Branched-chain amino acid aminotransferase was purified by several column chromatographies from Helicobacter pylori NCTC 11637, and the N-terminal amino acid sequence was analyzed. The enzyme gene was sequenced based on a putative branched-chain amino acid aminotransferase gene, ilvE of H. pylori 26695, and the whole amino acid sequence was deduced from the nucleotide sequence. The enzyme existed in a homodimer with a calculated subunit molecular weight (MW) of 37,539 and an isoelectric point (pI) of 6.47. The enzyme showed high affinity to 2-oxoglutarate (K (m) = 0.085 mM) and L-isoleucine (K (m) = 0.34 mM), and V (max) was 27.3 micromol/min/mg. The best substrate was found to be L-isoleucine followed by L-leucine and L-valine. No activity was shown toward the D-enantiomers of these amino acids. The optimal pH and temperature were pH 8.0 and 37 degrees C, respectively.

Plasma total homocysteine levels are associated with advanced leukoaraiosis but not with asymptomatic microbleeds on T2*-weighted MRI in patients with stroke

Both leukoaraiosis and asymptomatic microbleeds are associated with small-artery diseases. Although an association between hyperhomocysteinemia and leukoaraiosis has been reported, no studies have evaluated the association between total homocysteine (tHcy) level and presence of microbleeds in stroke patients. We evaluated the association between tHcy level and leukoaraiosis or microbleeds in stroke patients. In 102 patients with stroke (69.5 +/- 10.3 years old, 54 men and 48 women), microbleeds on T2*-weighted MR images were counted, leukoaraiosis on T2-weighted images was graded and fasting plasma tHcy concentrations were measured. Plasma tHcy level was significantly higher in patients with advanced leukoaraiosis than in those without advanced leukoaraiosis (13.9 +/- 4.6 micromol/l vs. 10.2 +/- 3.4 micromol/l, P < 0.0001). Plasma tHcy level was not significantly different in patients with microbleeds and those without microbleeds (11.3 +/- 4.1 micromol/l vs. 11.4 +/- 4.3 micromol/l, P = 0.9441). Elevated tHcy level is significantly and independently associated with advanced leukoaraiosis [odds ratio (OR), 1.330; 95% CI, 1.130-1.565] but not with the presence of microbleeds. Elevated tHcy level appears to be associated with ischemic small-artery disease rather than with bleeding-prone small-artery disease.

Combinations of the presence or absence of cerebral microbleeds and advanced white matter hyperintensity as predictors of subsequent stroke types

BACKGROUND AND PURPOSE

Previous studies have shown microbleeds to be a risk factor for intracerebral hemorrhage and white matter hyperintensity (WMH) to be a risk factor for ischemic stroke. This study was performed to determine whether combinations of the presence or absence of microbleeds and advanced WMH are risk factors for subsequent recurrent stroke types.

METHODS

In 266 patients with stroke, microbleeds on T2*-weighted MR images were counted, and WMH on T2-weighted images was graded. Patients were divided into 4 groups by the combinations of the presence or absence of microbleeds and advanced WMH and were followed up for stroke recurrence.

RESULTS

During a mean follow-up period of 564.8 +/- 220.5 days, 26 patients developed recurrent strokes, including 10 intracerebral hemorrhages and 16 ischemic strokes. Patients with microbleeds without advanced WMH (n = 42) developed only intracerebral hemorrhages (n = 8), and the recurrence rate of intracerebral hemorrhage in those patients estimated by the Kaplan-Meier method was the highest in the 4 groups (14.3% in 1 year and 21.2% in 2 years). In contrast, patients with advanced WMH without microbleeds (n = 39) developed only ischemic strokes (n = 6), and the estimated recurrent rate of ischemic stroke in those patients was the highest in the 4 groups (10.5% in 1 year and 17.4% in 2 years). Cox proportional hazards regression analysis revealed that microbleeds were associated with intracerebral hemorrhage (hazard ratio [HR], 85.626; 95% confidence interval [CI], 6.344-1155.649) and that advanced WMH was negatively associated with intracerebral hemorrhage (HR, 0.016; 95% CI, 0.001-0.258). Advanced WMH was associated with ischemic stroke (HR, 10.659; 95% CI, 2.601-43.678).

CONCLUSION

It appears that patients at high risk of subsequent intracerebral hemorrhage or ischemic stroke can be identified by combinations of the presence or absence of microbleeds and advanced WMH.

Effects of 30-m nitrox saturation dive on the immune system in man

Hyperbaria reportedly affects the immune system, but the role of psychological factors arising from confinement has not been taken into consideration. We investigated the immune changes in 4 subjects exposed to a 9-day simulated 30-m (400-kPa) nitrogen-oxygen (nitrox) saturation dive, and compared the results with those of our previous study that showed immune and mood changes in normobaric confinement. Blood samples were taken before, during, and after the dive or confinement, and activated with an anti-CD2 agonistic antibody. The percentages of granulocytes, natural killer (NK) cells, and cells positive for CD69, an early activation marker, were analyzed by flow cytometry. Reduction of CD69 expression percentage was observed under both hyperbaric and normobaric conditions. Percentages of innate immune cells, such as granulocytes and NK cells decreased or remained mostly unchanged, contrasting with our previous study, which demonstrated increases in both percentages coordinate with mood improvement. We conclude that these changes may have been triggered by suppression of sympathetic nerve activity that occurs in 30-m nitrox saturation hyperbaria.

Chemically modified thrombin and anhydrothrombin that differentiate macromolecular substrates of thrombin

BACKGROUND

Thrombin is a primary inducer of thrombus formation by activations of coagulation cascade and platelet aggregation. Hitherto, several types of thrombin inhibitors have been developed for therapeutic purpose.

OBJECTIVES

We prepared modified thrombin (M-thrombin) and modified anhydrothrombin (M-anhydrothrombin) by chemical modification of carboxyl groups of thrombin and anhydrothrombin, respectively, to present a new strategy for a potent antiplatelet-anticoagulant agent and new tools for investigation of thrombin functions.

RESULTS

M-anhydrothrombin retained high affinity for factor VIII (FVIII), but demonstrated lower affinity than anhydrothrombin for fibrinogen and factor V (FV). Both M-anhydrothrombin and anhydrothrombin prolonged activated partial thromboplastin time (APTT) without affecting prothrombin time, and M-anhydrothrombin prolonged APTT much more than anhydrothrombin. M-anhydrothrombin also retained affinity for the recombinant extracellular domain peptide of protease-activated receptor 1 (PAR1). M-thrombin exhibited marginal clotting activity (4% of thrombin), but induced platelet aggregation in platelet-rich plasma without forming a fibrin clot, which was completely suppressed by anti-PAR1 antibody (ATAP2) and by M-anhydrothrombin, but not by anhydrothrombin. These results indicate that M-thrombin induced platelet aggregation through the activation of PAR1, and M-anhydrothrombin inhibited this process completely. In contrast, neither M-anhydrothrombin nor anhydrothrombin apparently inhibited thrombin-induced platelet aggregation. Only in the presence of the Gly-Pro-Arg-Pro (GPRP) peptide that inhibits polymerization of fibrin, M-anhydrothrombin completely inhibited thrombin-induced platelet aggregation.

CONCLUSION

M-thrombin is PAR1-specific and M-anhydrothrombin is FVIII- and PAR1-specific derivatives, and thereby, are new tools as specific agonist and antagonist, respectively, of PAR1. Furthermore, M-anhydrothrombin may be an attractive model for development of a potent anticoagulant-antiplatelet agent.

Small low-density lipoprotein and small low-density lipoprotein/total low-density lipoprotein are closely associated with intima-media thickness of the carotid artery in Type 2 diabetic patients

BACKGROUND

The intima-media thickness (IMT) of the carotid artery, as determined by ultrasonography, is useful for reflecting the extent of subclinical atherosclerosis. We investigated the relationship between IMT and the serum concentrations of small low-density lipoprotein (LDL) in diabetic patients.

METHODS

The study was conducted with 27 Type 2 diabetic patients (14 males and 13 females; mean age=62.6+/-8.3 years) and 12 age-matched healthy controls. The LDL subfraction was measured using a polyacrylamide gel electrophoresis method. Vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) concentrations were measured by an enzyme immunoassay. The IMT was expressed as the maximum IMT (Max-IMT) and average IMT (Ave-IMT) of the carotid artery, measured by ultrasonography.

RESULTS

Both the IMT and the small LDL concentrations were significantly increased in the diabetic patients compared with the healthy participants. The IMTs were significantly correlated with small LDL concentration and small LDL/total LDL more than LDL concentrations by multivariate analysis. The IMTs were not significantly correlated with the serum VEGF or PDGF concentrations. The patients with a larger IMT had a significantly higher prevalence of hypertension or ischemic heart disease than did the patients with a normal IMT.

CONCLUSIONS

The increased small LDL concentrations and small LDL/total LDL, in addition to total LDL concentrations, in Type 2 diabetic patients are closely associated with increased IMT of the carotid artery.

Enhanced blood coagulation and fibrinolysis in mice lacking histidine-rich glycoprotein (HRG)

Histidine-rich glycoprotein (HRG) is a serum protein belonging to the cystatin superfamily. HRG may play a regulatory role in hemostasis and innate immunity. However, this role is uncertain because of a lack of rigorous testing in an animal model. We generated mice lacking the translation start point of exon 1 of the Hrg gene, effectively resulting in a null mutation (Hrg-/-). The mice were viable and fertile but had no HRG in their blood. Antithrombin activity in the plasma of Hrg-/- mice was higher than in the plasma of heterozygous Hrg+/- or wild-type Hrg+/+ mice. The prothrombin time was shorter in Hrg-/- mice than in Hrg+/- and Hrg+/+ mice. Bleeding time after tail tip amputation in Hrg-/- mice was shorter than in Hrg+/+ mice. The spontaneous fibrinolytic activity in clotted blood of Hrg-/- mice was higher than in Hrg+/+ mice. These findings suggest that HRG plays a role as both an anticoagulant and an antifibrinolytic modifier, and may regulate platelet function in vivo.

The effects of heat on the biological activity of recombinant human bone morphogenetic protein-2

This study was designed to investigate effects of heat on the bone-inducing activity of recombinant human bone morphogenetic protein (rhBMP)-2. rhBMP-2 samples were heated at 50, 70, 90, or 100 degrees C for 15 min, or 1, 2, 4, or 8 h, or autoclaved at 120 degrees C for 15 min. The bone-inducing activity of the rhBMP-2 before and after heating was assayed in in vivo and in vitro systems. For the in vivo assay, 5 microg rhBMP-2 samples were impregnated into porous collagen disks (6 mm in diameter, 1 mm thickness), freeze dried, and implanted into the back muscles of ddY mice. Three weeks later, the implant was harvested from the host and examined for ectopic new bone tissue by radiography. The new bone mass was quantified by single-energy X-ray absorptiometry. The in vitro activity of the rhBMP-2 was assayed by adding the BMP sample at a concentration of 100 ng/ml to cultures of MC3T3-E1 cells. After 48 h, the alkaline phosphatase activity was measured. After heating at 50 degrees or 70 degrees C, no significant reduction in bone-inducing activity was noted in either in vivo or in vitro assay systems unless the protein was exposed to sustained heat at 70 degrees C for 8 h, based on in vitro assay data. However, heating above 90 degrees C and for longer periods led to a decrease in the biological activity of the rhBMP-2 in a time- and temperature-dependent manner. rhBMP-2 was rendered inactive when exposed to temperatures at or in excess of 120 degrees C.

Assessment of microinvasion with reverse transcriptase polymerase chain reaction in a case of synovial sarcoma

The purpose of our study was to assess microinvasion in a case of synovial sarcoma by means of the reverse transcriptase polymerase chain reaction (RT-PCR) for detecting SYT-SSX fusion transcripts. Furthermore, we tried to compare the RT-PCR results with those obtained by conventional histopathological examination. A 45-year-old man with synovial sarcoma in the left lower leg underwent above-knee amputation and partial resection of the right lung because of local recurrence and metastasis to the lung. We obtained samples from the tumor and from locations at distances of 1, 3, and 5 cm from the tumor margin in the amputated limb. Samples were also obtained from the resected pulmonary tumor and peripheral blood. SYT-SSX1 chimeric genes could be detected in the samples obtained from up to 3 cm outside the tumor by RT-PCR. Histopathological examination confirmed tumor cells up to 1 cm from the tumor margin. We believe that using a molecular assay in addition to a histopathological examination provides a more sensitive and accurate assessment of the surgical margin.

Enhancement of recombinant human bone morphogenetic protein-2 (rhBMP-2)-induced new bone formation by concurrent treatment with parathyroid hormone and a phosphodiesterase inhibitor, pentoxifylline

We investigated the enhancement of new bone |formation elicited ectopically by recombinant human bone morphogenetic protein-2 (rhBMP-2), using parathyroid hormone (PTH) and a phosphodiesterase inhibitor (PDEi), pentoxifylline (PTX), in an animal model. Collagen sponge sheet discs containing rhBMP were implanted onto the back muscles of mice. PTX alone (200 mg/kg body weight [BW]), PTH(1-34) (10 microg/kg BW), PTX plus PTH (200 mg/kg BW and 10 microg/kg BW, respectively), or vehicle (control) were injected subcutaneously daily for 3 weeks after implantation. At the end of this period, rhBMP-2-induced ectopic ossicles were harvested from each group of animals. Ossicles from the PTX-treated group were significantly larger in size, with unchanged bone mineral density (BMD), as compared with the ossicles from the controls. In contrast, the ossicles from the PTH-treated group had significantly higher BMD, but showed no difference in size when compared with those from the control animals. The ossicles of the PTX + PTH treatment group were significantly larger than those of the control and PTH treatment groups. In addition, the BMD of the harvested tissues from the PTX + PTH treatment group was signifi-cantly higher than that of tissues from the control and PTX treatment groups. Although the calcium content of ossicles was significantly higher in the PTX-, PTH-, and PTX + PTH-treated groups than in the control group, the Ca content of ossicles from the PTH + PTX-treated group was highest (two times that of controls), followed by the PTH- and PTX-treated groups.

Temporal and spatial expression profiles of BMP receptors and noggin during BMP-2-induced ectopic bone formation

The mechanism of ectopic bone formation has not been clear. After BMP-2 implantation into the back muscles of 198 mice, expression of BMPR-1A, -2, and Noggin was increased during the early phase of the reaction. The results suggest that positive and negative feedback mechanisms modulate ectopic osteogenesis induced by this growth factor.

INTRODUCTION

The expression of bone morphogenetic protein receptors (BMPRs) and Noggin during ectopic bone formation after implantation of BMP-2 into the back muscles of adult mice was investigated in this study.

METHODS

One hundred ninety-eight male ddy mice were divided into groups and received either collagen disks containing BMP-2, collagen disks alone, or sham surgery with no disk implantation. Changes in the temporal and spatial expression profiles of BMPRs and Noggin were examined by Northern blotting, in situ hybridization, Western blotting, and immunohistochemistry.

RESULTS AND CONCLUSIONS

In the BMP group, expression of BMPR-1A, -2, and Noggin mRNA and protein was enhanced 2-4 days after implantation in undifferentiated mesenchymal cells and regenerating muscle fibers located close to the BMP-retaining implants. On day 7, the expression was also observed in cartilage cells, and after day 14, in the osteoblastic cells around bone tissue. The level of expression peaked at day 4 after implantation and persisted at a much lower level during the bone forming process. No significant expression of BMPR-1B was detected at the mRNA and protein levels during the bone-forming reaction. In the BMP free control groups, a mild enhancement of BMPR-2 expression was also noted around the implant, but this was not observed for BMPR-1A, -1B, or Noggin. Upregulated expression of BMPR-1A, -2, and Noggin in undifferentiated mesenchymal cells and regenerating muscle fibers occurs during the early phase of BMP-2-induced bone formation. The coordinate expression of these positive and negative regulators of BMP signaling points to a potential regulatory mechanism for bone induction.

A phosphodiesterase inhibitor, pentoxifylline, enhances the bone morphogenetic protein-4 (BMP-4)-dependent differentiation of osteoprogenitor cells

Bone morphogenetic protein-4 (BMP-4), a member of the transforming growth factor-beta superfamily, is capable of initiating differentiation of uncommitted mesenchymal cells into a chondro/osteogenic pathway. This study reports the effects of pentoxifylline (PTX), a nonspecific inhibitor of phosphodiesterases (PDEs), that causes elevation of the intracellular cyclic adenosine monophosphate (cAMP) level on the BMP-4-induced chondro/osteogenic differentiation of a mesenchymal cell line, C3H10T1/2; a bone marrow stromal cell line, ST2; and an osteoblastic cell line, MC3T3-E1. It was found that PTX enhanced BMP-4-induced chondro/osteogenic differentiation in C3H10T1/2 and ST2 cells. Similar effects were observed when adding dibutyryl-cAMP and forskolin. These results indicate that cAMP may potentiate the action of BMP-4 on osteoprogenitor cells, highlighting the possibility that PDE inhibitors could be used as therapeutic agents to enhance bone formation through this effect.

FK506 enhanced osteoblastic differentiation in mesenchymal cells

Bone morphogenetic protein (BMP) is a bone-derived growth factor capable of promoting the differentiation of mesenchymal cells into osteogenic lineage pathways. Recently, immunosuppressants were reported to cause a moderate increase in osteoblastic differentiation in a rat osteoblast-like osteosarcoma cell line. If immunosuppressants can induce osteoblastic differentiation, it will be useful for bone tissue transplantation. We assessed the effect of immunosuppressants with or without BMP-4 on inducing osteoblastic differentiation in osteoblast-like and other mesenchymal cells. FK506, an immunosuppressant often used clinically, induced a dose- and time-dependent increase in alkaline phosphatase (ALP) activity, one of the markers of osteoblast differentiation, in cells derived from mesenchyma. In the presence of BMP-4, ALP activity, mRNA levels of ALP and osteocalcin increased. FK506 was found to not only stimulate osteoblastic differentiation, but also to enhance BMP-4 induced osteoblastic differentiation. These results suggest that FK506 promotes differentiation of osteoblastic cells.

Effect of phosphodiesterase inhibitor-4, rolipram, on new bone formations by recombinant human bone morphogenetic protein-2

Collagen sponge disks (6 mm diameter, 1 mm thickness) were impregnated with recombinant human bone morphogenetic protein-2 (rhBMP-2) (5 microg/disk) and implanted onto the back muscles of mice. Ten or 20 mg/kg per day of Rolipram, a selective inhibitory agent to phosphodiesterase type 4 (PDE-4), or vehicle, was injected subcutaneously into the host mice for 3 weeks. After treatment, rhBMP-2-induced ectopic ossicles were harvested and examined by radiographic and histologic methods to determine the size, bone quality, and mineral content of the ossicles. The ossicles from a group treated with 20 mg/kg per day Rolipram were significantly larger in size and higher in bone mineral density (BMD) and bone mineral content (BMC) than the control samples. No significant differences were noted in mice treated with 10 mg/kg per day of Rolipram. Histologically, ossicles from the high-dose (20 mg/kg per day) Rolipram-treated group showed densely packed, thicker trabeculae when compared with those from the control group. These experimental results indicate that the PDE-4 inhibitor, Rolipram, may enhance the bone-inducing capacity of BMP-2 in mesenchymal cells. This in turn may result in increased responsiveness to BMP-2 and point to a potential use of PDE-4 inhibitors for the promotion of rhBMP-dependent bone repair.

A comparison of the healing potential of fibrillated cartilage versus eburnated bone in osteoarthritic knees after high tibial osteotomy: An arthroscopic study with 1-year follow-up

PURPOSE

To determine the healing potential of fibrillated cartilage in osteoarthritic (OA) knees when the mechanical condition is corrected.

TYPE OF STUDY

Prospective study.

METHODS

Subjects were patients treated with high tibial osteotomy alone for medial-compartment OA knees. They were divided into 2 groups on the basis of the Outerbridge classification; group A consisted of 37 grade IV knees (eburnation group), and group B consisted of 36 grade III knees (fibrillation group). Twelve months after surgery, the repair of joint cartilage was evaluated for arthroscopic finding and histology.

RESULTS

Arthroscopic examination of the femoral joint surface showed that, in group A, 9 knees (24%) were grade II, 14 (38%) were grade III, and 14 (38%) were grade IV; in group B, 3 knees (9%) were grade II, 30 (91%) were grade III, and none were grade IV. On the other hand, examination of the tibial joint surface showed that, in group A, 5 knees (16%) were grade II, 15 (47%) were grade III, and 12 (37%) were grade IV; in group B, 3 knees (9%) were grade II, 28 (80%) were grade III, and 5 (11%) were grade IV. Thus, the incidence of cartilage repair was significantly higher in group A than in group B on both femoral (P <.01) and tibial (P <.05) joint surface. Histologic findings showed most of the nonrepaired joint surface of fibrillated cartilage appeared to be hyaline cartilage, but repair tissues of eburnated bone were mainly fibrocartilage.

CONCLUSIONS

The repair of fibrillated cartilage was not promoted, but its degeneration was prevented by correction of the mechanical status. Our results show that fibrillated cartilage in OA knees has little potential for repair even though the mechanical status is corrected.

Involvement of phosphodiesterase isozymes in osteoblastic differentiation

The cyclic monophosphate nucleotides (cyclic adenosine monophosphate [cAMP] and cyclic guanosine monophosphate [cGMP]) are found ubiquitously in mammalian cells and act as second messenger transducers to effect the intracellular actions of a variety of hormones, cytokines, and neurotransmitters. In turn, these nucleotides also modulate the signal transduction processes regulated by a range of cytokines and growth factors. Previously, we have reported that pentoxifylline, a nonselective phosphodiesterase (PDE) inhibitor, can promote osteoblastic differentiation by elevating intracellular cAMP levels and, consequently, enhance bone formation in vivo and in vitro. In this study, reverse-transcription polymerase chain reaction (RT-PCR) analysis of the osteoblastic cell lines, MC3T3-E1 and ST2 revealed the presence of PDE1, PDE2, PDE3, PDE4, PDE7, PDE8, and PDE9. We examined the effect of selective inhibitors for a respective PDE isozyme on the capacity of bone morphogenetic protein 4 (BMP-4)-induced alkaline phosphatase (ALP) activity, a cellular differentiation marker, in cells with osteogenetic potential. The results indicate that selective inhibitors for PDE2, PDE3, and PDE4 enhanced the BMP-4-induced ALP activity in a dose-dependent manner in ST2 cells but not in MC3T3-E1 cells. Northern blot analysis also revealed that the selective inhibitors for PDE2, PDE3, and PDE4 enhanced the levels of expression of messenger RNAs (mRNAs) of ALP, osteopontin (OP), and collagen type I in ST2 cells but not in MC3T3-E1 cells except for the treatment with PDE4 inhibitor. Given these data, we conclude that PDE isozymes are involved in the modulation of osteoblastic differentiation mainly at an early stage. Additionally, selective inhibitors for PDE2, PDE3, and PDE4 appear to promote the differentiation of osteogenic precursor cells toward an osteoblastic phenotype.

NHE6 protein possesses a signal peptide destined for endoplasmic reticulum membrane and localizes in secretory organelles of the cell

The NHE6 protein is a unique Na(+)/H(+) exchanger isoform believed to localize in mitochondria. It possesses a hydrophilic N-terminal portion that is rich in positively charged residues and many hydrophobic segments. In the present study, signal sequences in the NHE6 molecule were examined for organelle localization and membrane topogenesis. When the full-length protein was expressed in COS7 cells, it localized in the endoplasmic reticulum and on the cell surface. Furthermore, the protein was fully N-glycosylated. When green fluorescent protein was fused after the second (H2) or third (H3) hydrophobic segment, the fusion proteins were targeted to the endoplasmic reticulum (ER) membrane. The localization pattern was the same as that of fusion proteins in which green fluorescent protein was fused after H2 of NHE1. In an in vitro system, H1 behaved as a signal peptide that directs the translocation of the following polypeptide chain and is then processed off. The next hydrophobic segment (H2) halted translocation and eventually became a transmembrane segment. The N-terminal hydrophobic segment (H1) of NHE1 also behaved as a signal peptide. Cell fractionation studies using antibodies against the 15 C-terminal residues indicated that NHE6 protein localized in the microsomal membranes of rat liver cells. All of the NHE6 molecules in liver tissue possess an endoglycosidase H-resistant sugar chain. These findings indicate that NHE6 protein is targeted to the ER membrane via the N-terminal signal peptide and is sorted to organelle membranes derived from the ER membrane.

Acute toxicity and mutagenicity study on branched corn syrup and evaluation of its laxative effect in humans

We developed a branched corn syrup (BCS, average molecular weight: 500, content of indigestible portion: 45%) by heat treatment of indigestible dextrin with hydrochloric acid. To confirm the safety of BCS, we conducted both an acute toxicity test and a mutagenicity test. Moreover, we observed gastroenteric effects of BCS in fifty healthy humans. The results are summarized as follows. 1) There was no death observed after oral administration of BCS in Sprague-Dawley-strain rats. Lethal dose (LD)50, value was estimated to be more than 10 g/kg body weight. 2) No mutagenicity was observed in Salmonella typhimurium TA98, TA100, TA1535, TA1537, or Escherichia coli WP2uvrA. 3) Fifty adults were divided into five groups often (five of each sex) and orally administered BCS at 0.2, 0.3, 0.4. 0.5 and 0.6 g/kg body weight as indigestible portion. Although no diarrhea was observed in females, BCS at 0.6 g/kg as indigestible portion caused diarrhea in two out of five males. The maximum non-effective dose of indigestible portion of BCS was estimated to be 0.5 g/kg in males and more than 0.6 g/kg in females.

Enhancement of bone morphogenetic protein-2-induced new bone formation in mice by the phosphodiesterase inhibitor pentoxifylline

Porous collagen disks (6 mm diameter, 1 mm thickness) were impregnated with recombinant human bone morphogenetic protein-2 (rhBMP-2) (5 microg/disk) and implanted onto the back muscles of mice. Pentoxifylline (PTX), which is a methylxanthine-derived inhibitor of phosphodiesterases (PDEs), or vehicle, was injected (5, 25, 50, 100, 200, and 300 mg/kg body weight/day) into the mice subcutaneously once a day for 3 weeks from the day of implantation of the bone morphogenetic protein (BMP)-laden disks. The rhBMP-2-induced ectopic ossicles were harvested and examined using radiographic, histological, and biochemical methods to determine size, bone quality, and calcium content. When compared with controls, ossicles from mice treated with >50 mg/kg per day of PTX were significantly larger in size and had a greater calcium content. However, no differences were noted in mice treated with lower doses (5 and 25 mg/kg per day) of PTX. The temporal sequence of the bone-forming process was unchanged by PTX based on histological examination. The histology of the ossicles from high- and low-dose PTX-treated mice was essentially identical to that observed in the control mice. These experimental results indicate that PTX enhanced the bone-inducing capacity of BMP-2. The underlying mechanism of action most likely involves the inhibition of intracellular phosphodiesterases and a resulting elevation of the intracellular content of cyclic nucleotides. Further studies are warranted to understand how BMP-induced bone formation is pharmacologically modified by PTX.

Calcineurin homologous protein as an essential cofactor for Na+/H+ exchangers

The Na+/H+ exchangers (NHEs) comprise a family of transporters that catalyze cell functions such as regulation of the pH and volume of a cell and epithelial absorption of Na+ and bicarbonate. Ubiquitous calcineurin B homologous protein (CHP or p22) is co-localized and co-immunoprecipitated with expressed NHE1, NHE2, or NHE3 independently of its myristoylation and Ca2+ binding, and its binding site was identified as the juxtamembrane region within the carboxyl-terminal cytoplasmic domain of exchangers. CHP binding-defective mutations of NHE1-3 or CHP depletion by injection of the competitive CHP-binding region of NHE1 into Xenopus oocytes resulted in a dramatic reduction (>90%) in the Na+/H+ exchange activity. The data suggest that CHP serves as an essential cofactor, which supports the physiological activity of NHE family members.

Comparative study of effects of angiotensin II receptor antagonist, KD3-671, and angiotensin converting enzyme inhibitor, enalaprilat, on cough reflex in guinea pig

Angiotensin converting enzyme (ACE) inhibitor prevents the inactivation of bradykinin by inhibiting ACE activity, leading to side effects such as dry cough and angioedema. KD3-671 is a novel nonpeptide angiotensin II antagonist which is expected to exhibit persistent hypotensive action without these side effects. In this study, we investigated the relationship between the pharmacokinetics and cough-inducing effect of this drug in guinea-pig, compared with that of an ACE inhibitor, enalaprilat. KD3-671 was not significantly different from the vehicle treatment in the ability to induce coughing, whereas enalaprilat significantly enhanced coughing compared with the vehicle treatment. Thus, as expected from its mechanism of pharmacological action, KD3-671 did not induce coughing. We suggest that the citric acid-induced guinea pig coughing model will be useful in preclinical studies to examine the effect of drug on pulmonary function.

Second mutations rescue point mutant of the Na(+)/H(+) exchanger NHE1 showing defective surface expression

We studied the effect of point mutation within the putative 11th transmembrane domain (TM11) of the Na(+)/H(+) exchanger NHE1 on the plasma membrane expression. Of the 19 mutants tested, two mutants (Tyr454 or Arg458 replaced by Cys) were retained in the endoplasmic reticulum. Interestingly, Y454C was expressed on the cell surface when one of the endogenous cysteine residues at position 8, 133, 421, or 477 was substituted with alanine. Random mutagenesis at Cys8 and its surrounding residues in the cytosolic N-tail revealed that replacement of Cys8 with Ala was the only identified single residue mutation that rescued Y454C. These results suggest that the abnormal conformation of the region of TM11 containing the Y454C mutation is compensated by the second mutation within other domains such as the N-tail. This approach may provide evidence for the interdomain interaction in NHE1.

Phosphodiesterase inhibitors, pentoxifylline and rolipram, increase bone mass mainly by promoting bone formation in normal mice

The administration of either Pentoxifylline (PTX), a methylxanthine derivative and an inhibitor of cyclic AMP (c-AMP) phosphodiesterases (PDEs), or Rolipram, an inhibitor specific to type-4 PDE (PDE4) in normal mice, significantly increased both cortical and cancellous bone mass. Vertebrae and tibiae from mice treated with PTX or Rolipram were analyzed by means of bone densitometry and histomorphometry. The results revealed that both PTX and Rolipram increased bone mass in normal mice mainly through the acceleration of bone formation. These findings suggest that both PTX and Rolipram can enhance physiological bone formation and thereby increase bone mass in normal mice. The possibility that these agents may be of value for the treatment of osteoporosis is discussed.

Histidine-rich glycoprotein (HRG) Tokushima 2: novel HRG deficiency, molecular and cellular characterization

The proband, a 76-year-old woman, suffered from dural arteriovenous fistula. Her plasma histidine-rich glycoprotein (HRG) level was 50% of the normal level. A low level of plasma HRG was also found in her third daughter. A single nucleotide substitution of T to C was found at nucleotide position 11,438 in exon 6 of the HRG gene from the proband, converting Cys223 to Arg in the second cystatin-like domain. The same mutation was also identified in her third daughter, but not in the other four family members having normal HRG levels or in 50 unrelated healthy Japanese individuals. Expression studies in BHK cells showed that substantial intracellular degradation of the mutant occurred and only about 40% of the recombinant HRG mutant was secreted. These results indicate that congenital HRG deficiency caused by a substitution of Cys223 to Arg is hereditary in this family.

Intracellular degradation of histidine-rich glycoprotein mutants: tokushima-1 and 2 mutants are degraded by different proteolytic systems

We reported the first case of a congenital histidine-rich glycoprotein deficiency (HRG Tokushima) in which substitution of Gly85 with Glu (G85E) in the first cystatin domain resulted in intracellular degradation and a low plasma level of HRG [Shigekiyo, T. et al. (1998) Blood 91, 128-133]. Recently, we identified the gene mutation of a second case of HRG deficiency as a Cys223 to Arg (C223R) mutation in the second cystatin domain. To investigate the molecular and cellular bases of these deficiencies, we expressed these HRG mutants in baby hamster kidney (BHK) cells. Pulse-chase experiments in the absence and presence of various proteinase inhibitors revealed that, while wild-type HRG was completely secreted during 4-h chase periods, both the G85E and C223R mutants were only partially secreted and primarily degraded within the cells. The intracellular degradation of the C223R mutant was almost completely inhibited in the presence of a proteasome inhibitor, lactacystin, carbobenzoxy-leucyl-leucyl-leucinal or N-acetyl-leucyl-leucyl-norleucinal, resulting in increased secretion of the C223R mutant, and thus implicating the proteasome system in this degradation process. In contrast, the sum of the amounts of the G85E mutant inside and outside the cells decreased during the chase periods even in the presence of the proteasome inhibitor, carbobenzoxy-leucyl-leucyl-leucinal or N-acetyl-leucyl-leucyl-norleucinal, although proteasome-specific inhibitor lactacystin and one of the cysteine protease inhibitors, E-64-d, prevented the intracellular degradation. These results suggested that intracellular degradation of G85E HRG occurred to some extent through a hitherto unknown mechanism. Similar studies involving recombinant mutants in which Gly85 or Cys223 was replaced with several other amino acids revealed that proteins with mutations leading to the destruction of the predicted b-sheet structure of the cystatin domains were eliminated by the intracellular quality control system.

A PET study of adenosine A1 receptor in anesthetized monkey brain

We demonstrated the distribution of adenosine A1 receptors in the anesthetized monkey brain with positron emission tomography (PET) using [(11)C]KF15372 ([1-propyl-(11)C]8-dicyclopropylmethyl-1, 3-dipropylxanthine). [(11)C]KF15372 was injected intravenously. The regional standardized uptake values and the distribution volume were calculated. We also investigated the effect of carrier on the uptake and regional brain distribution of [(11)C]KF15372. The use of [(11)C]KF15372 with dynamic PET scanning could be an appropriate method to analyze the regional binding potential of adenosine A1 receptors in living brain.

A novel topology model of the human Na(+)/H(+) exchanger isoform 1

The membrane topology of the human Na(+)/H(+) exchanger isoform 1 (NHE1) was assessed by substituted cysteine accessibility analysis. Eighty-three cysteine residues were individually introduced into a functional cysteineless NHE1, and these mutants were expressed in the exchanger-deficient PS120 cells. The topological disposition of introduced cysteines was determined by labeling with a biotinylated maleimide in the presence or absence of preincubation with the membrane-impermeable sulfhydryl reagent, 2-trimethylammoniumethyl-methanethiosulfonate in streptolysin O-permeabilized or nonpermeabilized cells. We proposed a new model for the topology of NHE1 that is significantly different from the model derived from hydropathy analysis. In this model, NHE1 is composed of 12 transmembrane segments (TMs) with the N and C termini located in the cytosol. The large, last extracellular loop in the membrane domain of the original model was suggested to comprise an intracellular loop, a new transmembrane segment (TM11), and an extracellular loop in the new model. Interestingly, cysteines at 183 and 184 and at 324 and 325 mapped to intracellular loops connecting TMs 4 and 5 (IL2) and TMs 8 and 9 (IL4), respectively, were accessible to sulfhydryl reagents from the outside. Furthermore, exchange activities of two mutants, R180C and Q181C, within IL2 were markedly inhibited by external MTSET. These data suggest that part of IL2 or IL4 may be located in a pore-lining region that is accessible from either side of the membrane and involved in ion transport.