Prevention of Unplanned Surgery Due to Delayed Diagnosis of Occult Ipsilateral Femoral Neck Fractures Associated with Femoral Shaft Fractures: A Study of the CT Capsular Sign with Lipohemarthrosis

BACKGROUND

The purpose of the present study was to investigate the effectiveness of using the computed tomography (CT) capsular sign with lipohemarthrosis of the hip joint as a selective indicator for preoperative magnetic resonance imaging (MRI) of the hip or prophylactic fixation of the ipsilateral femoral neck for the prevention of unplanned surgery due to delayed diagnosis of occult ipsilateral femoral neck fractures in patients with high-energy femoral shaft fractures.

METHODS

We evaluated the CT capsular sign with lipohemarthrosis in patients with a high-energy femoral shaft fracture without a preoperative diagnosis of an ipsilateral femoral neck fracture. The CT capsular sign with lipohemarthrosis was considered positive when the side-to-side difference in anterior capsular distension was >1 mm and lipohemarthrosis was seen on soft-tissue-window CT images. A positive CT capsular sign with lipohemarthrosis prompts preoperative hip MRI or prophylactic femoral neck fixation with a reconstruction nail.

RESULTS

One hundred and fifty-six consecutive patients were included. Eight patients were preoperatively diagnosed with a displaced or hairline ipsilateral femoral neck fracture, whereas the remaining 148 patients showed no ipsilateral femoral neck fracture on radiographs and bone-window CT images. On soft-tissue-window CT images, 29 (19.6%) of the 148 patients had a positive CT capsular sign with lipohemarthrosis. We performed preoperative MRI for 3 patients; in the remaining 26 patients, prophylactic femoral neck fixation was performed with a reconstruction nail. We identified 5 occult ipsilateral femoral neck fractures among the 29 patients with a positive sign: 2 on preoperative MRI scans, 2 on immediate postoperative radiographs, and 1 on radiographs made 6 weeks postoperatively. In 119 patients with a negative sign, no occult ipsilateral femoral neck fracture was identified. All occult ipsilateral femoral neck fractures healed without further displacement of the femoral neck. Consequently, additional unplanned surgery for delayed diagnosis of occult ipsilateral femoral neck fracture was not required.

CONCLUSIONS

The use of the CT capsular sign with lipohemarthrosis as a selective indicator for preoperative hip MRI or prophylactic femoral neck fixation with a reconstruction nail in patients with high-energy femoral shaft fractures is effective for preventing unplanned surgery due to delayed diagnosis of occult ipsilateral femoral neck fractures.

LEVEL OF EVIDENCE

Diagnostic Level I. See Instructions for Authors for a complete description of levels of evidence.

Triangular Osteosynthesis Using an S1 Pedicle Screw and S2 Alar Iliac Screw for a Unilateral Vertically Displaced Sacral Fracture

BACKGROUND

Managing unilateral vertically displaced sacral fractures remains a challenge. A triangular osteosynthesis (TOS), which involves fixing the fractured sacrum using unilateral spinopelvic fixation and a supplemental ilio-sacral screw, continues to gain popularity as it facilitates early mobilization and improves the long-term outcome. However, it has limitations, such as destruction of the L5-S1 joint, the need for additional removal surgery, and an increased risk of infection due to the large incision. An S1 pediculoiliac construct was proposed to overcome this limitations. Its use also has complications, however, including a painful hardware prominence due to the traditional iliac screw, excessive soft tissue retraction, and limited reduction capability.

CASE DESCRIPTION

A 20-year-old woman fell from a height of 6 meters and sustained a vertical shear type sacral fracture on the left side with substantial vertical displacement. We reduced and fixed the fracture using a TOS using an S1 pedicle screw and an S2 alar iliac screw (S2AIS). The patient was allowed immediate weight-bearing as tolerated. We achieved good reduction and union with a small vertical incision, without the destruction of L5-S1 joints, a symptomatic implant prominence, or wound complications.

CONCLUSIONS

For unilateral vertically unstable sacral fractures, TOS using S1 pedicle screws and S2AIS is safe and has the advantage such as maintaining mobility in the lumbar pelvic region, small size wounds, and reduced soft tissue damage, and it may have a potentially low infection rate. Further studies are needed to determine the specific indications and validate the effectiveness of this procedure.

Intramedullary Nailing for Atypical Femoral Fracture with Excessive Anterolateral Bowing

BACKGROUND

Intramedullary nailing is the treatment of choice for atypical femoral fractures. However, several problems, such as iatrogenic fracture and medial gap opening, can occur during intramedullary nailing when atypical femoral fractures are associated with excessive anterolateral bowing. To overcome these problems, we have developed a new grading system for anterolateral femoral bowing and a new technique for intramedullary nailing. The core of this new technique is matching the anterior curvature of the femoral nail with the anterolateral bowing of the femur when the nail passes the apex of the curvature, by rotating the nail externally.

METHODS

From January 2005 through March 2016, 24 female patients (30 cases) who underwent a surgical procedure for atypical femoral fracture with anterolateral bowing at 2 institutes were evaluated. The postoperative outcomes (anterolateral bowing grade, anterior and lateral bowing angles, medial gap and posterior gap of the fracture site, iatrogenic fracture, and time to initial medial callus formation and osseous union) were compared between the new technique (18 cases) and the conventional technique (12 cases).

RESULTS

With regard to the reliability of the new grading system, the interobserver and intraobserver reliability of the new grading system demonstrated an almost perfect agreement (kappainter = 0.893, kappaintra = 0.883). For patients with complete fractures, the differences between the preoperative and postoperative anterior and lateral bowing angles were significantly less (p = 0.013 for both) in the new technique group. The medial and posterior gaps at the fracture site were also significantly less in the new technique group (p = 0.013 for the medial gaps and p = 0.022 for the posterior gaps). Iatrogenic fracture occurred only in the conventional technique group, affecting 2 cases. The time to initial medial callus formation was significantly shorter (p = 0.033) in the new technique group compared with the conventional technique group.

CONCLUSIONS

Our new grading system for anterolateral femoral bowing is convenient and reliable. Furthermore, the new intramedullary nailing technique with the current intramedullary nail system is appropriate for the repair of atypical femoral fractures with excessive anterolateral bowing.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Atypical femoral fracture combined with osteonecrosis of jaw during osteoporosis treatment with bisphosphonate

Bisphosphonate, a potent anti-resorptive agent, is generally accepted as a safe, effective, well tolerated treatment for postmenopausal osteoporosis. Atypical femoral fracture (AFF) and bisphosphonate related osteonecrosis of jaw (BRONJ) are the increasing morbidities in patients treated with long term bisphosphonate. Pathogenic mechanisms of AFF and BRONJ are not fully identified and not identical. We report a case of BRONJ followed by AFF and its nonunion in a 67-year-old woman patient receiving an oral bisphosphonate during 7 years for the treatment of osteoporosis.

Fibroblast growth factor 21 improves insulin resistance and ameliorates renal injury in db/db mice

Despite the emerging importance of fibroblast growth factor 21 (FGF21) as a metabolic hormone regulating energy balance, its direct effects on renal function remain unexplored. FGF21 was injected ip daily for 12 weeks into db/db mice. Compared with control vehicle injection, FGF21 treatment significantly improved lipid profiles and insulin resistance and resulted in significantly higher serum adiponectin levels. In contrast, serum insulin and 8-isoprostane levels were significantly decreased. Interestingly, FGF21 and its receptor components in the kidneys were found to be significantly up-regulated in db/db mice, which suggests an FGF21-resistant state. FGF21 treatment significantly down-regulated FGF21 receptor components and activated ERK phosphorylation. FGF21 administration also markedly decreased urinary albumin excretion and mesangial expansion and suppressed profibrotic molecule synthesis. Furthermore, FGF21 improved renal lipid metabolism and oxidative stress injury. In cultured renal cells, FGF21 was mainly expressed in mesangial cells, and knockdown of FGF21 expression by stealth small interfering RNA further aggravated high-glucose-induced profibrotic cytokine synthesis in mesangial cells. Our results suggest that FGF21 improves insulin resistance and protects against renal injury through both improvement of systemic metabolic alterations and antifibrotic effects in type 2 diabetic nephropathy. Targeting FGF21 could therefore provide a potential candidate approach for a therapeutic strategy in type 2 diabetic nephropathy.

Renal protective effects of toll-like receptor 4 signaling blockade in type 2 diabetic mice

Chronic inflammation caused by high glucose and high free fatty acid (FFA) concentrations is a major contributor to the pathogenesis of type 2 diabetes. Recent evidence suggests that activation of Toll-like receptor (TLR) signaling induces peripheral insulin resistance and mediates central insulin and leptin resistance. In this study, we investigated the renal effects of TLR4 signaling blockade in type 2 diabetic mice. Eight-week-old db/db mice were treated for 12 weeks with (S,R)-3-phenyl-4,5-dihydro-5-isoxasole acetic acid (GIT27), which targets macrophages through the inhibition of TLR4- and TLR2/6-mediated signaling pathways. Although GIT27 treatment improved glycemic control and insulin tolerance, which is associated with a lower lipid profile, it did not impact body weight or food consumption. GIT27 treatment also markedly decreased urinary albumin excretion, decreased proinflammatory cytokine synthesis, improved tissue lipid metabolism, induced oxidative stress, and improved glomerulosclerosis compared with the control db/db group. In cultured podocytes and adipocytes, high glucose levels with FFA stimulation increased TLR4 expression and proinflammatory cytokine synthesis, but the effects were abolished by GIT27 treatment. In addition, knockdown of TLR4 expression by stealth small interfering RNA abolished FFA-induced proinflammatory cytokine synthesis in cultured podocytes. In conclusion, our results suggest that GIT27 treatment improves insulin resistance and protects against the renal injury that occurs in type 2 diabetic nephropathy through both metabolic and antiglomerulosclerotic mechanisms. These results suggest that TLR pathway inhibition might play a direct protective role in diabetic kidney disease.

Anatomical investigations for appropriate needle positioning for thoracic paravertebral blockade in children

OBJECTIVE

Clinicians hesitate to perform thoracic paravertebral blockade (TPVB) in children due to the potential high risk of adverse effects. No paediatric anatomical guidelines for TPVB exist. This study aimed to estimate the appropriate depth and distance for safe needle positioning in children.

METHODS

The depth (D) from the skin to the paravertebral space and the distance (A) from the spinous process to the needle entry point on the skin were measured using chest computed tomography (CT) in children aged between 1 and 9 years. Correlations between age, gender, weight, height, body mass index (BMI) and each of the anatomical measurements were analysed.

RESULTS

Each measurement correlated significantly with age, weight and height, but not with BMI (n = 373 children). Measurements A and D could be calculated by: A = 13.56 + (0.33 × age [years]) + (0.06 × weight [kg]) + 0.47 × (gender [female = 0, male = 1]); and D = 17.49 - (0.35 × age [years]) + (0.55 × weight [kg]).

CONCLUSION

These anatomical guidelines for TPVB are recommended to help prevent anaesthetic complications such as pneumothorax, when ultrasonography and CT are unavailable.

Recurrent posterior shoulder instability after rifle shooting

Rifle shooting produces a sudden counterforce against the body thorough the anterior shoulder, which may produce a traumatic injury in soldiers. Posterior instability of the shoulder can occur in soldiers who practice rifle shooting. To the authors' knowledge, few reports have examined shooting-related injuries in soldiers. This article describes the case of a 27-year-old male soldier who presented with left shoulder pain and instability after rifle training. He developed symptoms, and presented radiographic findings consistent with a posterior Bankart lesion. Intraoperatively, while in the lateral decubitus position, a posterior portal was created 3 cm inferior and 2 cm lateral to the posterolateral corner of acromion for making a proper angle for inserting anchors. A reverse bony Bankart lesion and adjacent cartilage breakdown at the glenoid rim were noted. An arthroscopic capsulolabral repair was performed with 3-mm bioabsorbable anchors to the glenoid rim. No gross reverse Hill-Sachs lesion or hyaline cartilage lesion was noted. Postoperatively, the arm was supported in a sling with an abduction pillow for 5 weeks. Codman's exercises, scapular protraction exercises, and elbow and wrist exercises were started. Physical therapy focused on reestablishing glenohumeral range of motion and rotator cuff and periscapular muscle strength. Six months postoperatively, the patient had normal scapular kinesis and reported no shoulder pain or symptoms of instability associated with a reverse bony Bankart lesion.

Clinical outcomes of autogenous cancellous bone grafts obtained through the portal for tibial nailing

BACKGROUND

The purpose of this study is to introduce and review the clinical outcomes of a new technique for harvesting autogenous cancellous bone grafts in association with tibial intramedullary (IM) nailing.

MATERIALS AND METHODS

We retrospectively reviewed 21 patients who received autogenous cancellous bone grafts obtained from the entry portal of a tibial IM nail for fracture gaps, malalignment or nonunion in the lower extremities. All patients were scheduled to receive IM nailing or had already received IM nailing for the fixation of an ipsilateral tibia shaft fracture. A total of 33 patients who received only tibial IM nailing were selected as a control group. Through the follow-up, postoperative complications related to the bone harvest were monitored. Further by taking serial X-rays, radiographic changes of the donor site and the knee joint were closely observed. Knee pain (visual analogue scale (VAS)) and function (Lysholm knee score) were compared between the study group and the control group.

RESULTS

At the last follow-up, the average VAS in the study group was 1.28 (0-5), which was not significantly different from the control group (VAS: 1.36, range 0-7) (P=0.985). The range of motion of the knee joint was similar in both groups, averaging 130.23° (range: 115-135°) and 131.36° (range: 115-135°), respectively. There was no significant difference in the Lysholm knee score between the study and control groups (P=0.610). All patients exhibited complete fracture healing at an average of 6 months and no complications associated with the bone donor site were observed.

CONCLUSIONS

By using the new technique, autogenous cancellous bone grafting can be performed conveniently and safely to treat fracture gaps, malalignment or nonunion in the lower extremities without additional morbidity at the donor site.

Blockade of cannabinoid receptor 1 improves insulin resistance, lipid metabolism, and diabetic nephropathy in db/db mice

The endocannabinoid system is important in the pathogenesis of obesity-related metabolic disorders. However, the effect of inhibiting the endocannabinoid system in type 2 diabetic nephropathy is unclear. Therefore, we examined the effect of the cannabinoid (CB)1 receptor antagonist, SR141716, on insulin resistance and diabetic nephropathy in db/db mice. Six-week-old db/db mice were treated with the CB1-specific antagonist SR141716 (10 mg/kg · d) for 3 months. Treatment with SR141716 significantly improved insulin resistance and lipid abnormalities. Concomitantly, CB1 antagonism improved cardiac functional and morphological abnormality, hepatic steatosis, and phenotypic changes of adipocytes into small differentiated forms, associated with increased adiponectin expression and decreased lipid hydroperoxide levels. CB1 receptor was overexpressed in diabetic kidneys, especially in podocytes. Treatment with the SR141716 markedly decreased urinary albumin excretion and mesangial expansion and suppressed profibrotic and proinflammatory cytokine synthesis. Furthermore, SR141716 improved renal lipid metabolism and decreased urinary 8-isoprostane levels, renal lipid hydroperoxide content, and renal lipid content. In cultured podocytes, high-glucose stimulation increased CB1 receptor expression, and SR141716 treatment abolished high-glucose-induced up-regulation of collagen and plasminogen activator inhibitor-1 synthesis. Additionally, knockdown of CB1 receptor expression by stealth small interfering RNA abolished high-glucose-induced sterol-regulatory element-binding protein-1 expression in podocytes. These findings suggest that CB1 blockade improves insulin resistance and protect against renal injury through both metabolic and antifibrotic effects in type 2 diabetic nephropathy. Targeting CB1 blockade could therefore provide a new therapeutic target to prevent type 2 diabetic nephropathy.

Influence of sirolimus on cyclosporine-induced pancreas islet dysfunction in rats

This study was performed to investigate the effect of sirolimus (SRL) on cyclosporine (CsA)-induced pancreatic islet dysfunction in rats. Three separate studies were performed. First, diabetogenic effect of SRL was evaluated with three different doses (0.15, 0.3 and 0.6 mg/kg). Second, rats were treated with SRL (0.3 mg/kg) with or without CsA (15 mg/kg) for 4 weeks. Third, rats were treated with CsA for 4 weeks, and then switched to SRL for 4 weeks. The effect of SRL on CsA-induced pancreatic islet dysfunction was evaluated by an intraperitoneal glucose tolerance test, plasma insulin concentration, HbA1c level, HOMA-R index, immunohistochemistry of insulin and pancreatic beta islet cell mass. The SRL treatment increased blood glucose concentration in a dose-dependent manner. The combined treatment with SRL and CsA increased blood glucose concentration, Hemoglobin A1c (HbA1c) level, HOMA-R [fasting insulin (mU/mL) x fasting glucose (mmol/L)]/22.5] index and decreased plasma insulin concentration, immunoreactivity of insulin and pancreatic beta islet cell mass compared with rats treated with CsA. CsA withdrawal for 4 weeks improved pancreatic beta-cell function and structure. However, conversion from CsA to SRL further increased blood glucose levels compared with the rats converted from vehicle to SRL. The results of our study demonstrate that SRL is diabetogenic and aggravates CsA-induced pancreatic islet dysfunction.

Paroxysmal stabbing headache in the multiple dermatomes of the head and neck: a variant of primary stabbing headache or occipital neuralgia?

A paroxysmal stabbing or icepick-like headache in the multiple nerve dermatomes, especially involving both trigeminal and cervical nerves, has not been fully explained or classified by the International Classification of Headache Disorder, 2(nd) Edition (ICHD-II). Of patients with acute-onset paroxysmal stabbing headache who had visited the Hallym University Medical Center during the last four years, 28 subjects with a repeated stabbing headache involving multiple dermatomes at the initial presentation or during the course were prospectively enrolled. All patients were neurologically and otologically symptom free. A coincidental involvement of both trigeminal and cervical nerve dermatomes included seven cases. Six cases involved initially the trigeminal and then cervical nerve dermatomes. Five cases showed an involvement of the cervical and then trigeminal nerve dermatomes. The remaining patients involved multiple cervical nerve branches (the lesser occipital, greater occipital and greater auricular). Pain lasted very shortly and a previous history of headache with the same nature was reported in 13 cases. Preceding symptom of an infection and physical and/or mental stress were manifested in seven and six subjects, respectively. All patients showed a self-limited benign course and completely recovered within a few hours to 30 days. Interestingly, a seasonal gradient in occurrence of a stabbing headache was found in this study. A paroxysmal stabbing headache manifested on multiple dermatomes can be explained by the characteristics of pain referral, and may be considered to be a variant of primary stabbing headache or occipital neuralgia.

Construction and calibration of a 50 T/m z-gradient coil for quantitative diffusion microimaging

q-Space imaging is capable of providing quantitative geometrical information of structures at cellular resolution. However, the size of restrictions that can be probed hinges on available gradient amplitude and places very high demands on gradient performance. In this work we describe the design and construction of a small, high-amplitude (50 T/m) z-gradient coil, interfaced with a commercial 9.4 T microimaging system. We also describe a method to calibrate the coil for quantitative measurements of molecular diffusion at very high-gradient amplitudes. Calibration showed linear current response up to 50 T/m, with a gain=1.255 T/m/A. The z-gradient coil was combined with the commercial x- and y-gradients for tri-axial imaging, and its performance was demonstrated by ADC maps of free water and by q-space experiments on water sequestered around polystyrene microspheres (4.5 microm diameter), which showed the expected diffraction peak. In addition, diffusion-weighted images of a fixed mouse spinal cord illustrated the capability of this coil for quantitative imaging of tissue microstructure.

Measurement of phosphorus content in normal and osteomalacic rabbit bone by solid-state 3D radial imaging

In osteomalacia decreased mineralization reduces the stiffness and static strength of bone. We hypothesized that hypomineralization in osteomalacic bone could be quantified by solid-state (31)P magnetic resonance imaging (SS-MRI). Hypomineralization was measured with a 3D radial imaging technique at 162 MHz (9.4T) in rabbit cortical bone of hypophosphatemic (HY) and normophosphatemic (NO) animals. The results were compared with those obtained by quantitative micro-CT (micro-CT) and (31)P solution NMR. 3D images of 277 microm isotropic voxel size were obtained in 1.7 hr with SNR approximately 9. Mineral content was lower in the HY relative to the NO group (SS-MRI: 9.48 +/- 0.4 vs. 11.15 +/- 0.31 phosphorus wet wt %, P < 0.0001; micro-CT: 1114.6 +/- 28.3 vs. 1175.7 +/- 23.5 mg mineral/cm(3); P = 0.003). T(1) was shorter in the HY group (47.2 +/- 3.5 vs. 54.1 +/- 2.7 s, P = 0.004), which suggests that relaxation occurs via a dipole-dipole (DD) mechanism involving exchangeable water protons, which are more prevalent in bone from osteomalacic animals.

Structural MRI of carotid artery atherosclerotic lesion burden and characterization of hemispheric cerebral blood flow before and after carotid endarterectomy

Collateral circulation plays a major role in maintaining cerebral blood flow (CBF) in patients with internal carotid artery (ICA) stenosis. CBF can remain normal despite severe ICA stenosis, making the benefit of carotid endarterectomy (CEA) or stenting difficult to assess. Before and after surgery, we assessed CBF supplied through the ipsilateral (stenotic) or contralateral ICA individually with a novel hemisphere-selective arterial spin-labeling (ASL) perfusion MR technique. We further explored the relationship between CBF and ICA obstruction ratio (OR) acquired with a multislice black-blood imaging sequence. For patients with unilateral ICA stenosis (n = 19), conventional bilateral labeling did not reveal interhemispheric differences. With unilateral labeling, CBF in the middle cerebral artery (MCA) territory on the surgical side from the ipsilateral supply (53.7 +/- 3.3 ml/100 g/min) was lower than CBF in the contralateral MCA territory from the contralateral supply (58.5 +/- 2.7 ml/100 g/min), although not statistically significant (p = 0.09). The ipsilateral MCA territory received significant (p = 0.02) contralateral supply (7.0 +/- 2.7 ml/100 g/min), while ipsilateral supply to the contralateral side was not reciprocated. After surgery (n = 11), ipsilateral supply to the MCA territory increased from 57.3 +/- 5.7 to 67.3 +/- 5.4 ml/100 g/min (p = 0.03), and contralateral supply to the ipsilateral MCA territory decreased. The best predictor of increased CBF on the side of surgery was normalized presurgical ipsilateral supply (r(2) = 0.62, p = 0.004). OR was less predictive of change, although the change in normalized contralateral supply was negatively correlated with OR(excess) (=OR(ipsilateral) - OR(contralateral)) (r(2) = 0.58, p = 0.006). The results demonstrate the effect of carotid artery stenosis on blood supply to the cerebral hemispheres, as well as the relative role of collateral pathways before surgery and redistribution of blood flow through these pathways after surgery. Unilateral ASL may better predict hemodynamic surgical outcome (measured by improved perfusion) than ICA OR.

Decomposition of CCl4 and CHCl3 on gliding are plasma

Decomposition of chlorinated hydrocarbons, CCl4 and CHCl3, in gliding plasma was examined. The effects of initial concentrations, total gas flow rates, and power consumption have been investigated. The conversion result was relatively high. It reached 80% for CCl4 and 97% for CHCl3. Using atmospheric air as the carrier gas, the plasma reaction occurred at exothermic reaction and the main products were CO2, CO, and Cl2. Transformation into CCl4 was also detected for CHCl3 decomposition reaction. The conversion of CCl4 and CHCl3 were increased with the increasing applied frequency and decreasing total gas flow rate.

Off pump coronary artery bypass surgery for significant left ventricular dysfunction: safety, feasibility, and trends in methodology over time--an early experience

OBJECTIVE

To examine the safety and applicability of off pump coronary artery bypass surgery (OPCAB) in patients with significant left ventricular dysfunction and to discuss the clinical implications for the surgical methods.

DESIGN

Retrospective study.

SETTING

Tertiary care university affiliated referral centre.

PARTICIPANTS

353 consecutive patients with preoperative left ventricular ejection fraction < or = 35% who underwent coronary artery bypass over a three year period.

MAIN OUTCOME MEASURES

Postoperative morbidity and mortality.

METHODS

144 patients operated by OPCAB were compared with 209 patients operated by conventional coronary artery bypass. Multivariate and univariate analyses were performed on the pre- and postoperative variables to predict risk factors associated with hospital morbidity and mortality.

RESULTS

Patients in the OPCAB group were more likely to be women and to have congestive heart failure, chronic obstructive pulmonary disease, hypertension, and diabetes; patients in the on pump group were more likely to have had a recent myocardial infarction and to have more severe angina pectoris and an urgent/emergent status. The groups did not differ significantly in length of stay, major postoperative complication rates, or mortality. Comparison of the impact of the procedures on surgical methods over time showed an increase in the use of OPCAB (13% to 67%), without any impact on morbidity or mortality.

CONCLUSIONS

OPCAB is feasible and applicable for patients with depressed left ventricular function. This high risk group can potentially benefit from the off pump approach.

Reproducibility and error sources of micro-MRI-based trabecular bone structural parameters of the distal radius and tibia

The mechanical competence of trabecular bone is significantly determined, next to material density, by its three-dimensional (3D) structure. Recent advances in micromagnetic resonance imaging (micro-MRI) acquisition and processing techniques allow the 3D trabecular structure to be analyzed in vivo at peripheral sites such as the distal radius and tibia. The practicality of micro-MRI-based noninvasive virtual bone biopsy (VBB) for longitudinal studies of patients hinges on the reproducibility of the derived structural parameters, which largely determine the size of the effect that can be detected at a given power and significance level. In this paper, the reproducibility of micro-MRI-derived trabecular bone structure measures was examined by performing repeat studies in six healthy subjects in whom the distal aspects of the radius and tibia were scanned with a 3D spin-echo sequence at 137 x 137 x 410 microm3 voxel size. Bone volume fraction (BV/TV) and digital topological analysis (DTA) structural parameters including the topological bone surface-to-curve ratio (SCR) and topological erosion index (TEI) were evaluated after subjecting the raw images to a cascade of processing steps. The average coefficient of variation was 4-7% and was comparable for the two anatomic sites and for all parameters measured. The reliability expressed in terms of the intraclass correlation coefficient ranged from 0.95 to 0.97 in the radius and 0.68 to 0.92 in the tibia. Error analysis based on simulations suggests involuntary patient motion, primarily rotation, to be the chief source of imprecision, followed by failure to accurately match the analysis volumes in repeat studies.

A noncontact, nondestructive method for quantifying intratissue deformations and strains

The function of soft connective tissues is frequently characterized by quantifying tissue strain (e.g., during joint motion). Conventional techniques for quantifying tendon and ligament strain typically provide surface measures, using markers, stain lines or instrumentation that may influence the tissue. An alternative approach is to quantify intratendinous strain by applying texture correlation analysis to magnetic resonance (MR) images. This paper reports the accuracy and reproducibility of this approach by (1) assessing the reproducibility of MR images, (2) assessing texture correlation accuracy using simulated displacements, and (3) comparing texture correlation measures of displacement and strain from MR images to conventional techniques.

Crystal structure of Klebsiella aerogenes UreE, a nickel-binding metallochaperone for urease activation

UreE is proposed to be a metallochaperone that delivers nickel ions to urease during activation of this bacterial virulence factor. Wild-type Klebsiella aerogenes UreE binds approximately six nickel ions per homodimer, whereas H144*UreE (a functional C-terminal truncated variant) was previously reported to bind two. We determined the structure of H144*UreE by multi-wavelength anomalous diffraction and refined it to 1.5 A resolution. The present structure reveals an Hsp40-like peptide-binding domain, an Atx1-like metal-binding domain, and a flexible C terminus. Three metal-binding sites per dimer, defined by structural analysis of Cu-H144*UreE, are on the opposite face of the Atx1-like domain than observed in the copper metallochaperone. One metal bridges the two subunits via the pair of His-96 residues, whereas the other two sites involve metal coordination by His-110 and His-112 within each subunit. In contrast to the copper metallochaperone mechanism involving thiol ligand exchanges between structurally similar chaperones and target proteins, we propose that the Hsp40-like module interacts with urease apoprotein and/or other urease accessory proteins, while the Atx1-like domain delivers histidyl-bound nickel to the urease active site.

Enhanced IL-18 expression in common skin tumors

Interleukin-18 (IL-18) has been found to have multiple effects upon various cells involved in inflammatory response. Recently we reported that B16 murine melanoma cells are able to produce IL-18, which is involved in the regulation of intracellular reactive oxygen intermediates (ROI) and Fas-ligand expression, indicating that IL-18 plays key role in the tumor activity of melanoma. In this study, we investigated the pattern of IL-18 expression in the human system. IL-18 production was tested by enzyme linked immunosorbent assay (ELISA) assay in various tumor cell lines, including Raji (Burkitt's lymphoma), IM-9 (B lymphoblast), Jurkat (acute T cell leukemia), SK-MES-1 (squamous cell carcinoma (SCC) cell line), SK-MEL-2, G-361, DM-4, and DX-3 (melanoma cell lines). ELISA tests showed that IL-18 was highly expressed in malignant skin tumors such as SK-MES-1, SK-MEL-2, G-361, DM-4, and DX-3 cell lines, thus suggesting that IL-18 production may be associated with the malignancy of skin tumors. Here, we report that enhanced IL-18 expression is positively correlated with malignant skin tumors such as SCC and melanoma, suggesting the importance role of IL-18 in malignancy of skin tumors. Taken together, expression of IL-18 by tumor cells in human skin tissue may provide an important clue to understand the pathogenesis of malignant skin tumors.

Pulmonary MR angiography with contrast agent at 4 Tesla: a preliminary result

In this study, pulmonary MR angiography (MRA) using a tailored coil at 4 Tesla in conjunction with an intravenous injection of contrast agent is described. Three-dimensional gradient-echo images were obtained during the intravenous injection of 0.05, 0.1, and 0.2 mmol/kg body weight of gadodiamide to investigate the signal enhancement effect of the contrast agent in pulmonary arteries qualitatively and quantitatively. In the qualitative analysis, the subsegmental branches were visualized on every dose. In the quantitative analysis, the average contrast-to-noise ratios (CNRs) of the main pulmonary arteries increased in a dose-dependent manner. However, the CNRs of segmental arteries did not increase as the dose of contrast agent increased, as observed at 1.5 Tesla MRI. These observations demonstrate the feasibility of delineating the pulmonary vasculature using a contrast agent; however, our results also suggest possible high-field-related disabilities that need to be overcome before high-field (> or =4 Tesla) MRI can be used to full advantage.

Contrasting effects of zonisamide and acetazolamide on amygdaloid kindling in rats

PURPOSE

Zonisamide (ZNS) and acetazolamide (AZM) are two antiepileptic drugs (AEDs) that differ in clinical efficacy. To elucidate the mechanisms of action of these compounds, we investigated their therapeutic and prophylactic effects in rats by using a kindling model of partial epilepsy.

METHODS

Electrodes were implanted into the left amygdala of adult male Wistar rats. The animals were stimulated at the afterdischarge threshold until five stage 5 seizures were induced. The generalized seizure threshold was then determined. Therapeutic effects were examined in rats manifesting successive convulsions with near-threshold stimulation. To test prophylactic effects, drugs were administered intraperitoneally before daily kindling stimulation until the animal had a stage 5 seizure or reached day 18.

RESULTS

ZNS (10-40 mg/kg; n=6) suppressed kindled seizures in a dose-dependent manner. Repeated administration for 7 days produced tolerance to anticonvulsive effects. AZM (25-200 mg/kg; n=7) showed limited therapeutic effect, alleviating only the clonic convulsion in stage 5 seizures and reducing afterdischarge duration. Secondary generalization was not significantly suppressed during repeated treatment (50-200 mg/kg; n=6). ZNS, 25 or 40 mg/kg (n=8), significantly retarded seizure development; 15.0 or 17.0 daily stimulations were required to produce a stage 5 seizure. AZM, 50-200 mg/kg (n=6), also retarded seizure development, with 14.0-14.8 stimulations required.

CONCLUSIONS

ZNS exhibited modest therapeutic and prophylactic effects, whereas AZM showed mainly prophylactic effects. Hypotheses are presented that may explain the mechanisms of action of these drugs.

Impaired activation of islet-reactive CD4 T cells in pancreatic lymph nodes of B cell-deficient nonobese diabetic mice

Despite the impressive protection of B cell-deficient (muMT(-/-)) nonobese diabetic (NOD) mice from spontaneous diabetes, existence of mild pancreatic islet inflammation in these mice indicates that initial autoimmune targeting of beta cells has occurred. Furthermore, muMT(-/-) NOD mice are shown to harbor a latent repertoire of diabetogenic T cells, as evidenced by their susceptibility to cyclophosphamide-induced diabetes. The quiescence of this pool of islet-reactive T cells may be a consequence of impaired activation of T lymphocytes in B cell-deficient NOD mice. In this regard, in vitro anti-CD3-mediated stimulation demonstrates impaired activation of lymph node CD4 T cells in muMT(-/-) NOD mice as compared with that of wild-type counterparts, a deficiency that is correlated with an exaggerated CD4 T cell:APC ratio in lymph nodes of muMT(-/-) NOD mice. This feature points to an insufficient availability of APC costimulation on a per T cell basis, resulting in impaired CD4 T cell activation in lymph nodes of muMT(-/-) NOD mice. In accordance with these findings, an islet-reactive CD4 T cell clonotype undergoes suboptimal activation in pancreatic lymph nodes of muMT(-/-) NOD recipients. Overall, the present study indicates that B cells in the pancreatic lymph node microenvironment are critical in overcoming a checkpoint involving the provision of optimal costimulation to islet-reactive NOD CD4 T cells.

Simultaneous acquisition of multiple resolution images for dynamic contrast enhanced imaging of the breast

An imaging technique is described that allows the reconstruction of a series of images at high temporal rates, while simultaneously providing images at high spatial resolution. The method allows one to arbitrarily choose from among several combinations of temporal/spatial resolutions during postprocessing. This flexibility is accomplished by strategically interleaving multiple undersampled projection reconstruction datasets (or subapertures), in which each set can be used to reconstruct a high temporal resolution image. Images with increasingly higher spatial resolutions can subsequently be formed by combining two or more subaperture datasets. The technique is demonstrated in vivo to assess the kinetics of contrast enhancement and to visualize the architectural features of suspicious breast lesions.

The quaternary arrangement of HslU and HslV in a cocrystal: a response to Wang, Yale

Protease HslV and ATPase HslU form an ATP-dependent protease in bacteria. We have previously determined the structure of the components of this protease. In the case of HslU, the structure was derived from HslU-HslV cocrystals, combining phase information from MAD and the previously determined HslV model. Whereas the structures of the components were confirmed in detail by later structures, the quaternary arrangement of HslV and HslU was not reproduced in later crystal forms. In a recent communication to this journal, Wang attempted a reinterpretation of our original data to account for this difference. In response, we demonstrate that difference Pattersons, difference Fouriers, molecular replacement calculations, R factors, and omit maps all support our original analysis and prove that the suggested reinterpretation is false by these criteria. In particular, we show that our crystals are essentially untwinned and that only the originally reported quaternary arrangement of HslV and HslU particles is consistent with the experimental data. We finally demonstrate that Wang's newly introduced R(tpart) method to predict translational corrections for a subset of the unit cell contents is systematically flawed.

Comparison of activation requirements and activation phenotype of allogeneic and xenogeneic rodent responses in vivo and in vitro

BACKGROUND

Both discordant and concordant xenogeneic responses are dominated by humoral immunity. Recent advances in molecular engineering approaches may largely prevent rejection by means of this pathway, leaving the cellular arm of the immune response as the principal remaining barrier to successful engraftment.

METHODS

To characterize further the cellular response to xenogeneic tissues, we used the intracellular fluorescent marker CFSE (5-(and-6)-carboxyfluorescein diacetate succinimidyl ester) to track the mitotic record of T cells (and T cell subsets) after either xenogeneic or allogeneic activation in vitro or in vivo. Activation marker expression was monitored by simultaneous labeling with antibodies for either CD25 or CD134.

RESULTS

The in vitro and in vivo responses of Lewis lymphocytes were generally similar in magnitude and timing comparing activation with allogeneic or xenogeneic stimulators. However, the xenogeneic T cell precursor frequency was found to be markedly higher than that previously reported and were comparable to that seen in allogeneic responses. Xenogeneic responses were unique in the continued expression of activation markers in later division cycles. In addition, CD4 and CD8 T-cell proliferation was highly dependent on stimulator class II expression, highlighting the importance of CD4 T cells and the indirect pathway in the xenogeneic response.

CONCLUSIONS

An unexpectedly high precursor frequency was detected for xenogeneic cellular responses in the rat anti-mouse combination and was comparable to that seen in allogeneic responses. Differences in xenogeneic versus allogeneic activation profiles exist that may result from the cellular pathways used for activation.

Digital topological analysis of in vivo magnetic resonance microimages of trabecular bone reveals structural implications of osteoporosis

Osteoporosis is a disease characterized by bone volume loss and architectural deterioration. The majority of work aimed at evaluating the structural implications of the disease has been performed based on stereologic analysis of histomorphometric sections. Only recently noninvasive imaging methods have emerged that provide sufficient resolution to resolve individual trabeculae. In this article, we apply digital topological analysis (DTA) to magnetic resonance microimages (mu-MRI) of the radius obtained at 137 x 137 x 350 microm3 voxel size in a cohort of 79 women of widely varying bone mineral density (BMD) and vertebral deformity status. DTA is a new method that allows unambiguous determination of the three-dimensional (3D) topology of each voxel in a trabecular bone network. The analysis involves generation of a bone volume fraction map, which is subjected to subvoxel processing to alleviate partial volume blurring, followed by thresholding and skeletonization. The skeletonized images contain only surfaces, profiles, curves, and their mutual junctions as the remnants of trabecular plates and rods after skeletonization. DTA parameters were compared with integral BMD in the lumbar spine and femur as well as MR-derived bone volume fraction (BV/TV). Vertebral deformities were determined based on sagittal MRIs of the spine with a semiautomatic method and the number of deformities counted after threshold setting. DTA structural indices were found the strongest discriminators of subjects with deformities from those without deformities. Subjects with deformities (n = 29) had lower topological surface (SURF) density (p < 0.0005) and surface-to-curve ratio (SCR; a measure of the ratio of platelike to rodlike trabeculae; p < 0.0005) than those without. Profile interior (PI) density, a measure of intact trabecular rods, was also lower in the deformity group (p < 0.0001). These data provide the first in vivo evidence for the structural implications inherent in postmenopausal osteoporosis accompanying bone loss, that is, the conversion of trabecular plates to rods and disruption of rods due to repeated osteoclastic resorption.

Trabecular bone volume fraction mapping by low-resolution MRI

Trabecular bone volume fraction (TBVF) is highly associated with the mechanical competence of trabecular bone. TBVF is ordinarily measured by histomorphometry from bone biopsies or, noninvasively, by means of high-resolution microcomputed tomography and, more recently, by micro-MRI. The latter methods require spatial resolution sufficient to resolve trabeculae, along with segmentation techniques that allow unambiguous assignment of the signal to bone or bone marrow. In this article it is shown that TBVF can be measured under low-resolution conditions by exploiting the attenuation of the MR signal resulting from fractional occupancy of the imaging voxel by bone and bone marrow, provided that a reference signal is available from a marrow volume devoid of trabeculation. The method requires accurate measurement of apparent proton density, which entails correction for various sources of error. Key among these are the spatial nonuniformity in the RF field amplitude and effects of the slice profile, which are determined by B(1) field mapping and numerical integration of the Bloch equations, respectively. By contrast, errors from variations in bone marrow composition (hematopoietic vs. fatty) between trabecular and reference site are predicted to be small and usually negligible. The method was evaluated in phantoms and in vivo in the distal radius and found to be accurate to 1% in marrow volume fraction. Finally, in a group of 12 patients of varying skeletal status, TBVF in the calcaneus was found to strongly correlate with integral bone mineral density of the lumbar vertebrae (r(2) = 0.83, p < 0.0001). The method may fail in large imaging objects such as the human trunk at high magnetic field where standing wave and RF penetration effects cause intensity variations that cannot be corrected. Magn Reson Med 46:103-113, 2001.

Structural basis of non-specific lipid binding in maize lipid-transfer protein complexes revealed by high-resolution X-ray crystallography

Non-specific lipid-transfer proteins (nsLTPs) are involved in the movement of phospholipids, glycolipids, fatty acids, and steroids between membranes. Several structures of plant nsLTPs have been determined both by X-ray crystallography and nuclear magnetic resonance. However, the detailed structural basis of the non-specific binding of hydrophobic ligands by nsLTPs is still poorly understood. In order to gain a better understanding of the structural basis of the non-specific binding of hydrophobic ligands by nsLTPs and to investigate the plasticity of the fatty acid binding cavity in nsLTPs, seven high-resolution (between 1.3 A and 1.9 A) crystal structures have been determined. These depict the nsLTP from maize seedlings in complex with an array of fatty acids.A detailed comparison of the structures of maize nsLTP in complex with various ligands reveals a new binding mode in an nsLTP-oleate complex which has not been seen before. Furthermore, in the caprate complex, the ligand binds to the protein cavity in two orientations with equal occupancy. The volume of the hydrophobic cavity in the nsLTP from maize shows some variation depending on the size of the bound ligands. The structural plasticity of the ligand binding cavity and the predominant involvement of non-specific van der Waals interactions with the hydrophobic tail of the ligands provide a structural explanation for the non-specificity of maize nsLTP. The hydrophobic cavity accommodates various ligands from C10 to C18. The C18:1 ricinoleate with its hydroxyl group hydrogen bonding to Ala68 possibly mimics cutin monomer binding which is of biological importance. Some of the myristate binding sites in human serum albumin resemble the maize nsLTP, implying the importance of a helical bundle in accommodating the non-specific binding of fatty acids.

Nutritional support for Crohn's disease

This article reviews nutritional considerations that arise in the care of patients with Crohn's disease. The causes and presentation of malnutrition in these patients are discussed, and a rational method is presented for comprehensive nutritional assessment. The indications for nutritional intervention, either as supportive or primary therapy for Crohn's disease, are reviewed.

MRI measurement of brain iron in patients with restless legs syndrome

Brain iron insufficiency in the restless legs syndrome (RLS) has been suggested by a prior CSF study. Using a special MRI measurement (R2'), the authors assessed regional brain iron concentrations in 10 subjects (five with RLS, five controls). R2' was significantly decreased in the substantia nigra, and somewhat less significantly in the putamen, both in proportion to RLS severity. The results show the potential utility of this MRI measurement, and also indicate that brain iron insufficiency may occur in patients with RLS in some brain regions.

Mutational studies on HslU and its docking mode with HslV

HslVU is an ATP-dependent prokaryotic protease complex. Despite detailed crystal and molecular structure determinations of free HslV and HslU, the mechanism of ATP-dependent peptide and protein hydrolysis remained unclear, mainly because the productive complex of HslV and HslU could not be unambiguously identified from the crystal data. In the crystalline complex, the I domains of HslU interact with HslV. Observations based on electron microscopy data were interpreted in the light of the crystal structure to indicate an alternative mode of association with the intermediate domains away from HslV. By generation and analysis of two dozen HslU mutants, we find that the amidolytic and caseinolytic activities of HslVU are quite robust to mutations on both alternative docking surfaces on HslU. In contrast, HslVU activity against the maltose-binding protein-SulA fusion protein depends on the presence of the I domain and is also sensitive to mutations in the N-terminal and C-terminal domains of HslU. Mutational studies around the hexameric pore of HslU seem to show that it is involved in the recognition/translocation of maltose-binding protein-SulA but not of chromogenic small substrates and casein. ATP-binding site mutations, among other things, confirm the essential role of the "sensor arginine" (R393) and the "arginine finger" (R325) in the ATPase action of HslU and demonstrate an important role for E321. Additionally, we report a better refined structure of the HslVU complex crystallized along with resorufin-labeled casein.

k-space weighted image contrast (KWIC) for contrast manipulation in projection reconstruction MRI

A novel technique for manipulating contrast in projection reconstruction MRI is described. The method takes advantage of the fact that the central region of k-space is oversampled, allowing one to choose different filters to enhance or reduce the amount that each view contributes to the central region, which dominates image contrast. The technique is implemented into a fast spin-echo (FSE) sequence, and it is shown that multiple T(2)-weighted images can be reconstructed from a single image data set. These images are shown to be nearly identical to those acquired with the Cartesian-sampled FSE sequence at different effective echo times. Further, it is demonstrated that T(2) maps can be generated from a single image data set. This technique also has the potential to be useful in dynamic contrast enhancement studies, capable of yielding a series of images at a significantly higher effective temporal resolution than what is currently possible with other methods, without sacrificing spatial resolution.

Nucleoside diphosphate kinase from the hyperthermophilic archaeon Methanococcus jannaschii: overexpression, crystallization and preliminary X-ray crystallographic analysis

Nucleoside diphosphate (NDP) kinase is a key enzyme in maintaining cellular pools of all nucleoside triphosphates. NDP kinase from the hyperthermophilic archaebacterium Methanococcus jannaschii has been overexpressed in Escherichia coli and crystallized at 297 K using polyethylene glycol 4000 as precipitant. The crystal is hexagonal, belonging to the space group P6(3), with unit-cell parameters a = b = 72.89, c = 100.87 A. The asymmetric unit contains two subunits of NDP kinase, with a corresponding crystal volume per protein mass (V(M)) of 2.38 A(3) Da(-1) and a solvent content of 48.3%. Native X-ray diffraction data to 2.30 A resolution have been collected using synchrotron X-rays.

Cross-sectional study of osteopenia with quantitative MR imaging and bone densitometry

PURPOSE

To evaluation the cancellous bone-induced intravoxel spin dephasing rate (R2') and its relationship to bone mineral density and marrow fat and to examine these parameters as predictors of vertebral fracture status.

MATERIALS AND METHODS

R2' and R2, the rate constants for reversible and irreversible spin dephasing, and marrow fat fraction were measured in the lumbar vertebrae and proximal femur. One hundred thirty-nine subjects (mean age, 62.4 years +/- 11.4 [SD]; 33 men, 106 women) had spinal dual-energy x-ray absorptiometric bone mineral density (BMD) T scores ranging from +3 to -5. R2', BMD, and bone marrow composition as determinants of vertebral fracture status were examined.

RESULTS

Strongest single predictors of fracture status for BMD and R2' were the Ward triangle (r(2) = 0.48) and trochanter (r(2) = 0.37), respectively. Combined, the two parameters and sites increased fracture prediction (r(2) = 0. 62), whereas the combination of multiple BMD sites did not. Multivariate regression involving marrow fat fraction further improved fracture status prediction. R2' was correlated with BMD at all sites, although slopes differed by a factor of up to 2.5, which reflected differences in trabecular orientation relative to the static field. R2, the true transverse relaxation rate, was negatively correlated with marrow fat fraction. A non-age-related increase in marrow fat fraction in osteoporosis parallels earlier findings in animal models.

CONCLUSION

Cancellous bone marrow R2' measured in the proximal femur provides information, which, with BMD, improves prediction of vertebral fracture status.

Impaired CD4 T cell activation due to reliance upon B cell-mediated costimulation in nonobese diabetic (NOD) mice

Diabetes in nonobese diabetic (NOD) mice results from the activation of I-A(g7)-restricted, islet-reactive T cells. This study delineates several characteristics of NOD CD4 T cell activation, which, independent of I-A(g7), are likely to promote a dysregulated state of peripheral T cell tolerance. NOD CD4 T cell activation was found to be resistant to antigenic stimulation via the TCR complex, using the progression of cell division as a measure. The extent of NOD CD4 T cell division was highly sensitive to changes in Ag ligand density. Moreover, even upon maximal TCR complex-mediated stimulation, NOD CD4 T cell division prematurely terminated. Maximally stimulated NOD CD4 T cells failed to achieve the threshold number of division cycles required for optimal susceptibility to activation-induced death, a critical mechanism for the regulation of peripheral T cell tolerance. Importantly, these aberrant activation characteristics were not T cell-intrinsic but resulted from reliance on B cell costimulatory function in NOD mice. Costimulation delivered by nonautoimmune strain APCs normalized NOD CD4 T cell division and the extent of activation-induced death. Thus, by disrupting the progression of CD4 T cell division, polarization of APC costimulatory function to the B cell compartment could allow the persistence and activation of diabetogenic cells in NOD mice.

Hand-assisted laparoscopic vertical banded gastroplasty: early results

BACKGROUND

Minimally invasive hand-port-assisted laparoscopic vertical banded gastroplasty has the potential to reduce postoperative complications after bariatric surgery.

METHODS

We analyzed the postoperative course of 46 hand-port-assisted laparoscopic vertical banded gastroplasties (LVBG) completed between January 1998 and April 1999.

RESULTS

The operating time for the LVBG was shorter (140.8 +/- 6.0 vs 180.2 +/- 6.3 min; p < 0.05). Individuals were able to ambulate sooner (1.36 +/- 0.09 vs 2.44 +/- 0.16 days; p < 0.05), and start oral intake earlier (2.7 +/- 0.27 vs 3.7 +/- 0.17 days; p < 0.05) than the open vertical banded gastroplasty (VBG) controls. Three staple line leaks were detected in this group. Two leaks resolved without clinical sequelae, but one patient developed intraabdominal sepsis. This complication extended the average hospital stay to 6.8 +/- 2.00 days, as compared to 7.71 +/- 0.18 days for historical controls. By discounting this patient from the analysis, we arrive at a more representative length of hospitalization of 4.82 +/- 0.34 days (p < 0.05).

CONCLUSIONS

LVBG offers a good alternative to the standard open VBG. Although this procedure has a relatively short learning curve, it should be done at centers with an interest in bariatric surgery.

High-speed spectroscopic imaging for cancellous bone marrow R(2)* mapping and lipid quantification

In this work an interleaved multiple-gradient-echo chemical shift imaging (IMGE-CSI) technique was designed, implemented and evaluated at 1.5 and 4T for high-resolution lipid quantification and R(2)* measurement in-vivo. The method is analogous to echo planar CSI but utilizes conventional gradient echoes, exploiting the principle of spectroscopic bandwidth extension by interleaving temporally offset gradient-echo trains. It is shown that IMGE-CSI is able to measure true fat volume fraction in oil/water mixtures with high accuracy, not possible with Dixon-type methods which approximate the spectrum as consisting of only two spectral components. Correlation of the CSI- derived volume fractions with volumetry afforded r(2) > 0.99 with a slope of 0.98. The method is shown to be able to quantify regional variations in bone marrow composition in vivo with a spatial resolution of 2.5 x 2.5 x 5 mm(3.) R(2)* was obtained by multi-line spectral curve fitting. For the measurement of R(2)* in cancellous bone marrow the method is shown to agree well with time-domain fitting techniques but is superior in instances where the marrow has both hematopoietic and fatty constituents. Finally, excellent inter-scan reproducibility (1% coefficient of variation for global means and medians) was achieved, yielding r(2) = 0.98 of the test-retest correlation for three scans in four test subjects. In conclusion, IMGE-CSI is found to enable highly accurate lipid quantification and measurement of cancellous bone marrow R(2)* at spatial resolutions and scan times typical of standard clinical protocols.

Crystal structure of Escherichia coli CyaY protein reveals a previously unidentified fold for the evolutionarily conserved frataxin family

Friedreich ataxia is an autosomal recessive neurodegenerative disease caused by defects in the FRDA gene, which encodes a mitochondrial protein called frataxin. Frataxin is evolutionarily conserved, with homologs identified in mammals, worms, yeast, and bacteria. The CyaY proteins of gamma-purple bacteria are believed to be closely related to the ancestor of frataxin. In this study, we have determined the crystal structure of the CyaY protein from Escherichia coli at 1.4-A resolution. It reveals a protein fold consisting of a six-stranded antiparallel beta-sheet flanked on one side by two alpha-helices. This fold is likely to be shared by all members of the conserved frataxin family. This study also provides a framework for the interpretation of disease-associated mutations in frataxin and for understanding the possible functions of this protein family.

Crystallization and preliminary X-ray crystallographic analysis of Escherichia coli CyaY, a structural homologue of human frataxin

CyaY is a 106-residue protein from Escherichia coli. It shows amino-acid sequence similarity to human frataxin and a frataxin homologue in Saccharomyces cerevisiae, Yfh1p. The former is associated with the disease Friedreich ataxia and the latter plays a key role in iron homeostasis in mitochondria. CyaY has been overexpressed in soluble form in E. coli. The recombinant protein with a His(6) tag at its C-terminus has been crystallized at 296 K using polyethylene glycol (PEG) 4000 as a precipitant. Native diffraction data have been collected to 1.8 A using Cu Kalpha X-rays. The crystals belong to the trigonal space group P3(1)21 (or P3(2)21), with unit-cell parameters a = b = 44.66, c = 99.87 A, alpha = beta = 90.0, gamma = 120.0 degrees. The asymmetric unit contains one molecule of recombinant CyaY, with a corresponding V(m) of 2.13 A(3) Da(-1) and solvent content of 42.3%.

Crystallization and preliminary X-ray diffraction analysis of Saccharomyces cerevisiae Ygr203p, a homologue of Acr2 arsenate reductase

Ygr203p, a 148-residue protein encoded by the ygr203w gene of Saccharomyces cerevisiae, is a homologue of the yeast Acr2 arsenate reductase encoded by the acr2 (or ypr200c) gene. It also shows significant sequence similarity to the human cell-cycle control Cdc25 phosphatase family. It has been overexpressed in soluble form in Escherichia coli with a His(6) tag at its C-terminus. The recombinant protein has been crystallized at 296 K using sodium chloride as precipitant. The crystals belong to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 40.48, b = 50.95, c = 91.95 A. The asymmetric unit contains a monomer, giving a crystal volume per protein mass (V(m)) of 2.61 A(3) Da(-1) and a solvent content of 53.8%. The crystals diffract to better than 1.9 A resolution with Cu Kalpha X-rays. They are therefore suitable for high-resolution structure determination.

Crystallization and preliminary X-ray crystallographic analysis of human nucleoside diphosphate kinase A

Human nucleoside diphosphate kinase A catalyzes phosphoryl transfer and acts as a suppressor of metastasis. It has been crystallized using 2-methyl-2,4-pentanediol as a precipitant at 288 K. The crystal is monoclinic, belonging to the space group P2(1), with unit-cell parameters a = 74.21, b = 78.11, c = 82.29 A, beta = 101. 33 degrees. The asymmetric unit contains a homohexamer, with a corresponding crystal volume per protein mass (V(m)) of 2.27 A(3) Da(-1) and a solvent content of 46%. Native X-ray data to 2.15 A resolution have been collected using synchrotron X-rays.

Topological analysis of trabecular bone MR images

Recently, imaging techniques have become available which permit nondestructive analysis of the three-dimensional (3-D) architecture of trabecular bone (TB), which forms a network of interconnected plates and rods. Most osteoporotic fractures occur at locations rich in TB, which has spurred the search for architectural parameters as determinants of bone strength. In this paper, we present a new approach to quantitative characterization of the 3-D microarchitecture of TB, based on digital topology. The method classifies each voxel of the 3-D structure based on the connectivity information of neighboring voxels. Following conversion of the 3-D digital image to a skeletonized surface representation containing only one-dimensional (1-D) and two-dimensional (2-D) structures, each voxel is classified as a curve, surface, or junction. The method has been validated by means of synthesized images and has subsequently been applied to TB images from the human wrist. The topological parameters were found to predict Young's modulus (YM) for uniaxial loading, specifically, the surface-to-curve ratio was found to be the single strongest predictor of YM (r2 = 0.69). Finally, the method has been applied to TB images from a group of patients showing very large variations in topological parameters that parallel much smaller changes in bone volume fraction (BVF).

Crystal structure of NAD(+)-dependent DNA ligase: modular architecture and functional implications

DNA ligases catalyze the crucial step of joining the breaks in duplex DNA during DNA replication, repair and recombination, utilizing either ATP or NAD(+) as a cofactor. Despite the difference in cofactor specificity and limited overall sequence similarity, the two classes of DNA ligase share basically the same catalytic mechanism. In this study, the crystal structure of an NAD(+)-dependent DNA ligase from Thermus filiformis, a 667 residue multidomain protein, has been determined by the multiwavelength anomalous diffraction (MAD) method. It reveals highly modular architecture and a unique circular arrangement of its four distinct domains. It also provides clues for protein flexibility and DNA-binding sites. A model for the multidomain ligase action involving large conformational changes is proposed.

The structures of HsIU and the ATP-dependent protease HsIU-HsIV

The degradation of cytoplasmic proteins is an ATP-dependent process. Substrates are targeted to a single soluble protease, the 26S proteasome, in eukaryotes and to a number of unrelated proteases in prokaryotes. A surprising link emerged with the discovery of the ATP-dependent protease HslVU (heat shock locus VU) in Escherichia coli. Its protease component HslV shares approximately 20% sequence similarity and a conserved fold with 20S proteasome beta-subunits. HslU is a member of the Hsp100 (Clp) family of ATPases. Here we report the crystal structures of free HslU and an 820,000 relative molecular mass complex of HslU and HslV-the first structure of a complete set of components of an ATP-dependent protease. HslV and HslU display sixfold symmetry, ruling out mechanisms of protease activation that require a symmetry mismatch between the two components. Instead, there is conformational flexibility and domain motion in HslU and a localized order-disorder transition in HslV. Individual subunits of HslU contain two globular domains in relative orientations that correlate with nucleotide bound and unbound states. They are surprisingly similar to their counterparts in N-ethylmaleimide-sensitive fusion protein, the prototype of an AAA-ATPase. A third, mostly alpha-helical domain in HslU mediates the contact with HslV and may be the structural equivalent of the amino-terminal domains in proteasomal AAA-ATPases.

In vivo MR micro imaging with conventional radiofrequency coils cooled to 77 degrees K

Cryogenically cooled conventional surface coils are shown to provide significant signal-to-noise ratio (SNR) gains for MR micro imaging of tissue structure in vivo. Measurements are described which employ a simple, all-polyvinyl chloride (PVC) vacuum dewar capable of maintaining a bath of liquid nitrogen around the coil, within 5 mm of the tissue to be imaged. Images acquired in vivo at 64 MHz with a 2-cm diameter copper coil cooled to 77 K demonstrated a gain in SNR of approximately 2.7 +/- 0.3 relative to those obtained with the same coil at room temperature under otherwise identical conditions. This increase is consistent with the reduction in coil resistance and the minor contribution to overall resistance from the imaging object. The performance of the coil is illustrated with images from the human finger and rabbit eye and potential applications are discussed.

Ligation of ICAM-1 molecules inhibits target cell-induced granule exocytosis of IL-12-activated natural killer cells

The importance of cell adhesion molecules such as ICAM-1 is emphasized in cell-to-cell interactions that are critical in the generation of effective immune reactions. In this study, the involvement of ICAM-1 in natural killer (NK) cell activities was characterized in IL-12-activated human NK cells. To address the question of whether ligation of ICAM-1 molecules can modulate NK cell cytolytic activities, a 4-h (51)Cr-release assay was performed after pretreatment of NK cells with R6.5 mAb (anti-human ICAM-1 mAb). Ligation of membrane ICAM-1 molecules significantly inhibited IL-12-enhanced NK cytotoxicity against K562, and the pretreatment of neutralizing soluble ICAM-1 with R6.5 mAb blocked this inhibitory effect. The involvement of Ca(2+)-dependent granular exocytosis was evaluated. BLT esterase assay demonstrated that the ligation of ICAM-1 molecules inhibited granular exocytosis of NK cells. Additionally, the ICAM-1-mediated inhibition of Ca(2+) flux in NK cells was detected using Fluo-3AM, while the pretreatment of NK cells with R6.5 mAb did not affect conjugate formation between NK and K562 cells. Collectively, these results suggest that the signals transduced from ICAM-1 molecules might be sufficient to induce inhibitory effects on NK cells.