Don't Let the Sun Rise on Small Bowel Obstruction Without Surgical Consultation-Redefining Nonoperative Management Pathways

Introduction: Small bowel obstruction (SBO) is a common cause of hospital admission leading to resource utilization. The majority of these patients require non-operative management (NOM) which can lead to increased length of stay (LOS), readmissions, resource utilization, and throughput delays. Early surgical consultation (SC) for SBO may improve efficiency and outcomes. Methods: We implemented an institution-wide intervention (INT) to encourage early SC (<1 day of diagnosis) for SBO patients in July 2022. A retrospective analysis was performed on all patients with SBO requiring NOM from January 2021 to June 2023, categorized into pre- and post-INT groups. The primary outcome was the number of SC's and secondary outcomes were early SC (<1 day of diagnosis), utilization of SBFT, LOS, 30-day readmission, and costs of admission. Results: A total of 670 patients were included, 438 in the pre-INT and 232 in the post-INT group. Overall, SBFT utilization was significantly higher in cases with SC (17.2% vs 41.4%, P < .001). Post-INT patients were more likely to receive SC (94.0% vs 83.3%, P < .001) and increased SBFT utilization (47.0% vs 33.6%, P = .001). Additionally, early SC improved significantly in the post-INT group (74.3% vs 65.7%, P = .03). There was no difference in LOS between groups (4.0 vs 3.8 days, P = .48). There was a trend toward decreased readmission rates in the INT group at 30 days (7.3% vs 11.0%, P = .13) and reduced direct costs in the INT group (US$/admission = 8467 vs 8708, P = .1). Conclusion: Hospital-wide interventions to increase early surgical involvement proved effective by improving early SC, increased SBFT utilization, and showed a trend towards decreased readmission rates and direct costs.

[Analysis of etiology and complications in children with stage 5 chronic kidney disease]

Objective: To investigate the etiology, complications, and prognostic factors of stage 5 chronic kidney disease (CKD5) in children. Methods: A case series study was conducted to retrospectively analyze the general situation, clinical manifestations, laboratory tests, genetic testing, and follow-up data (until October 2022) of 174 children with CKD5 who were diagnosed and hospitalized at the Children's Hospital of Chongqing Medical University from April 2012 to April 2021. The characteristics of complications in the children were compared based on age, gender, and etiology. Based on the presence or absence of left ventricular hypertrophy (LVH), patients were divided into LVH group and non LVH group for analyzing the influencing factors of cardiovascular disease. Patients were also divided into death group and survival group, peritoneal dialysis group and hemodialysis group based on the follow-up data for analyzing the prognostic factors. The chi-square test, independent sample t-test, Fisher exact probability test, Mann-Whitney U test and Kruskal Wallis test were used to analyze data among different groups. Multivariate Logistic regression analysis was used to identify the prognostic factors. Results: A total of 174 children with CKD5 were enrolled in the study (96 boys and 78 girls), aged 11.2 (8.2, 13.0) years. Congenital kidney and urinary tract malformations (CAKUT) were the most common causes of the CKD5 (84 cases, 48.3%), followed by glomerular diseases (83 cases, 47.7%), and among which 28 cases (16.1%) were hereditary glomerular diseases. The common complications of CKD5 included anemia (98.2%, 165/168), mineral and bone disorder in chronic kidney disease (CKD-MBD) (97.7%, 170/174), lipid metabolism disorders (87.5%, 63/72), hypertension (81.4%, 127/156) and LVH (57.6%,57/99). The incidences of hypertension in primary glomerular disease were higher than that in CAKUT(93.8%(30/32) vs.73.7%(56/76),χ2=5.59,P<0.05). The incidences of hypertension in secondary glomerular disease were higher than that in CAKUT and that in hereditary kidney disease (100.0%(20/20) vs. 73.7%(56/76), 68.2%(15/22), both P<0.05). The incidence of hypocalcemia in CAKUT, primary glomerular disease, and hereditary kidney disease was higher than that in secondary glomerular disease (82.1%(69/84), 88.2%(30/34), 89.3%(25/28) vs. 47.6%(10/21), χ2=10.21, 10.75, 10.80, all P=0.001); the incidence of secondary hyperparathyroidism in women was higher than that in men (80.0%(64/80) vs. 95.0%(57/60), χ2=6.58, P=0.010). The incidence of LVH in children aged 6-<12 was higher than that in children aged 12-18 (73.5%(25/34) vs. 43.1%(22/51), χ2=7.62, P=0.006). Among 113 follow-up children, the mortality rate was 39.8% (45/113). Compared to the survival group, the children in the death group had lower hemoglobin, higher blood pressure, lower albumin, lower alkaline phosphatase and higher left ventricular mass index ((67±19) vs. (75±20) g/L, 142 (126, 154) vs. 128(113, 145) mmHg(1 mmHg=0.133 kPa), (91±21) vs. (82±22) mmHg, 32 (26, 41) vs. 40 (31, 43) g/L, 151 (82, 214) vs. 215 (129, 37) U/L, 48 (38, 66) vs. 38(32, 50) g/m2.7,t=2.03, Z=2.89, t=2.70, Z=2.49, 2.79, 2.29,all P<0.05), but no independent risk factors were identified (all P>0.05). The peritoneal dialysis group had better alleviation for anemia, low calcium, and high phosphorus than the hemodialysis group ((87±22) vs. (72±16) g/L, (1.9±0.5) vs. (1.7±0.4) mmol/L, (2.2±0.7) vs. (2.8±0.9) mmol/L, t=2.92, 2.29, 2.82, all P<0.05), and the survival rate of the peritoneal dialysis group was significantly higher than that of the hemodialysis group (77.8% (28/36) vs. 48.4% (30/62), χ2=8.14, P=0.004). Conclusions: CAKUT is the most common etiology in children with CKD 5, and anemia is the most common complication. The incidence of complications in children with CKD 5 varies with age, gender and etiology. Anemia, hypertension, hypoalbuminemia, reduced alkaline phosphatase and elevated LVMI may be the prognostic factors in children with CKD5. Peritoneal dialysis may be more beneficial for improving the long-term survival rate.

Understanding ultrarare adverse events - Lessons learned from a twelve-year review of intraoperative deaths at an academic medical center

BACKGROUND

Intraoperative death (ID) is rare, the incidence remains challenging to quantify and learning opportunities are limited. We aimed to better define the demographics of ID by reviewing the longest single-site series.

METHODS

Retrospective chart reviews, including a review of contemporaneous incident reports, were performed on all ID between March 2010 to August 2022 at an academic medical center.

RESULTS

Over 12 years, 154 IDs occurred (∼13/year, average age: 54.3 years, male: 60%). Most occurred during emergency procedures (n = 115, 74.7%), 39 (25.3%) during elective procedures. Incident reports were submitted in 129 cases (84%). 21 (16.3%) reports cited 28 contributing factors including challenges with coordination (n = 8, 28.6%), skill-based errors (n = 7, 25.0%), and environmental factors (n = 3, 10.7%).

CONCLUSIONS

Most deaths occurred in patients admitted from the ER with general surgical problems. Despite expectations for incident reporting, few provided actionable information on ergonomic factors which might help identify improvement opportunities.

The Impact of IV Electrolyte Replacement on the Fluid Balance of Critically Ill Surgical Patients

Avoiding excess fluid administration is necessary when managing critically ill surgical patients. The aim of this study was to delineate the current practices of IVelectrolyte (IVE) replacement in a surgical ICU and quantify their contribution to the fluid balance (FB) status. Patients admitted to the surgical ICU over a six-month period were reviewed. Patients undergoing dialysis and those with ICU stay <72 hours were excluded. A total of 248 patients were included. The median age was 60 years, and 57 per cent were male. Overall, 1131 patient ICU days were analyzed. The median daily FB was 672 mL. IVEs were administered in 62 per cent of ICU days. In days that IVEs were used, negative FB was significantly less likely to be achieved (62% vs 69%, P = 0.02). The most commonly administered IVE was calcium (32% of ICU days); however, the largest volume of IVE was administered in the form of phosphorus (median 225 mL). Diuretics were administered in 17 per cent of ICU days. Patients who received diuretics were significantly more likely to receive IVE (70% vs 61%, P = 0.02). Administration of IVE may contribute to the daily positive FB of surgical ICU patients. Implementation of practices that can ameliorate this effect is encouraged.

The Impact of IV Electrolyte Replacement on the Fluid Balance of Critically Ill Surgical Patients

Avoiding excess fluid administration is necessary when managing critically ill surgical patients. The aim of this study was to delineate the current practices of IV electrolyte (IVE) replacement in a surgical ICU and quantify their contribution to the fluid balance (FB) status. Patients admitted to the surgical ICU over a six-month period were reviewed. Patients undergoing dialysis and those with ICU stay <72 hours were excluded. A total of 248 patients were included. The median age was 60 years, and 57 per cent were male. Overall, 1131 patient ICU days were analyzed. The median daily FB was 672 mL. IVEs were administered in 62 per cent of ICU days. In days that IVEs were used, negative FB was significantly less likely to be achieved (62% vs 69%, P = 0.02). The most commonly administered IVE was calcium (32% of ICU days); however, the largest volume of IVE was administered in the form of phosphorus (median 225 mL). Diuretics were administered in 17 per cent of ICU days. Patients who received diuretics were significantly more likely to receive IVE (70% vs 61%, P = 0.02). Administration of IVE may contribute to the daily positive FB of surgical ICU patients. Implementation of practices that can ameliorate this effect is encouraged.

Known-Component 3D-2D Registration for Image Guidance and Quality Assurance in Spine Surgery Pedicle Screw Placement

PURPOSE

To extend the functionality of radiographic/fluoroscopic imaging systems already within standard spine surgery workflow to: 1) provide guidance of surgical device analogous to an external tracking system; and 2) provide intraoperative quality assurance (QA) of the surgical product.

METHODS

Using fast, robust 3D-2D registration in combination with 3D models of known components (surgical devices), the 3D pose determination was solved to relate known components to 2D projection images and 3D preoperative CT in near-real-time. Exact and parametric models of the components were used as input to the algorithm to evaluate the effects of model fidelity. The proposed algorithm employs the covariance matrix adaptation evolution strategy (CMA-ES) to maximize gradient correlation (GC) between measured projections and simulated forward projections of components. Geometric accuracy was evaluated in a spine phantom in terms of target registration error at the tool tip (TRE _x ), and angular deviation (TRE _ϕ ) from planned trajectory.

RESULTS

Transpedicle surgical devices (probe tool and spine screws) were successfully guided with TRE _x <2 mm and TRE _ϕ <0.5° given projection views separated by at least >30° (easily accommodated on a mobile C-arm). QA of the surgical product based on 3D-2D registration demonstrated the detection of pedicle screw breach with TRE _x <1 mm, demonstrating a trend of improved accuracy correlated to the fidelity of the component model employed.

CONCLUSIONS

3D-2D registration combined with 3D models of known surgical components provides a novel method for near-real-time guidance and quality assurance using a mobile C-arm without external trackers or fiducial markers. Ongoing work includes determination of optimal views based on component shape and trajectory, improved robustness to anatomical deformation, and expanded preclinical testing in spine and intracranial surgeries.

Dual-energy cone-beam CT with a flat-panel detector: effect of reconstruction algorithm on material classification

PURPOSE

Cone-beam CT (CBCT) with a flat-panel detector (FPD) is finding application in areas such as breast and musculoskeletal imaging, where dual-energy (DE) capabilities offer potential benefit. The authors investigate the accuracy of material classification in DE CBCT using filtered backprojection (FBP) and penalized likelihood (PL) reconstruction and optimize contrast-enhanced DE CBCT of the joints as a function of dose, material concentration, and detail size.

METHODS

Phantoms consisting of a 15 cm diameter water cylinder with solid calcium inserts (50-200 mg/ml, 3-28.4 mm diameter) and solid iodine inserts (2-10 mg/ml, 3-28.4 mm diameter), as well as a cadaveric knee with intra-articular injection of iodine were imaged on a CBCT bench with a Varian 4343 FPD. The low energy (LE) beam was 70 kVp (+0.2 mm Cu), and the high energy (HE) beam was 120 kVp (+0.2 mm Cu, +0.5 mm Ag). Total dose (LE+HE) was varied from 3.1 to 15.6 mGy with equal dose allocation. Image-based DE classification involved a nearest distance classifier in the space of LE versus HE attenuation values. Recognizing the differences in noise between LE and HE beams, the LE and HE data were differentially filtered (in FBP) or regularized (in PL). Both a quadratic (PLQ) and a total-variation penalty (PLTV) were investigated for PL. The performance of DE CBCT material discrimination was quantified in terms of voxelwise specificity, sensitivity, and accuracy.

RESULTS

Noise in the HE image was primarily responsible for classification errors within the contrast inserts, whereas noise in the LE image mainly influenced classification in the surrounding water. For inserts of diameter 28.4 mm, DE CBCT reconstructions were optimized to maximize the total combined accuracy across the range of calcium and iodine concentrations, yielding values of ∼ 88% for FBP and PLQ, and ∼ 95% for PLTV at 3.1 mGy total dose, increasing to ∼ 95% for FBP and PLQ, and ∼ 98% for PLTV at 15.6 mGy total dose. For a fixed iodine concentration of 5 mg/ml and reconstructions maximizing overall accuracy across the range of insert diameters, the minimum diameter classified with accuracy >80% was ∼ 15 mm for FBP and PLQ and ∼ 10 mm for PLTV, improving to ∼ 7 mm for FBP and PLQ and ∼ 3 mm for PLTV at 15.6 mGy. The results indicate similar performance for FBP and PLQ and showed improved classification accuracy with edge-preserving PLTV. A slight preference for increased smoothing of the HE data was found. DE CBCT discrimination of iodine and bone in the knee was demonstrated with FBP and PLTV at 6.2 mGy total dose.

CONCLUSIONS

For iodine concentrations >5 mg/ml and detail size ∼ 20 mm, material classification accuracy of >90% was achieved in DE CBCT with both FBP and PL at total doses <10 mGy. Optimal performance was attained by selection of reconstruction parameters based on the differences in noise between HE and LE data, typically favoring stronger smoothing of the HE data, and by using penalties matched to the imaging task (e.g., edge-preserving PLTV in areas of uniform enhancement).

dPIRPLE: a joint estimation framework for deformable registration and penalized-likelihood CT image reconstruction using prior images

Sequential imaging studies are conducted in many clinical scenarios. Prior images from previous studies contain a great deal of patient-specific anatomical information and can be used in conjunction with subsequent imaging acquisitions to maintain image quality while enabling radiation dose reduction (e.g., through sparse angular sampling, reduction in fluence, etc). However, patient motion between images in such sequences results in misregistration between the prior image and current anatomy. Existing prior-image-based approaches often include only a simple rigid registration step that can be insufficient for capturing complex anatomical motion, introducing detrimental effects in subsequent image reconstruction. In this work, we propose a joint framework that estimates the 3D deformation between an unregistered prior image and the current anatomy (based on a subsequent data acquisition) and reconstructs the current anatomical image using a model-based reconstruction approach that includes regularization based on the deformed prior image. This framework is referred to as deformable prior image registration, penalized-likelihood estimation (dPIRPLE). Central to this framework is the inclusion of a 3D B-spline-based free-form-deformation model into the joint registration-reconstruction objective function. The proposed framework is solved using a maximization strategy whereby alternating updates to the registration parameters and image estimates are applied allowing for improvements in both the registration and reconstruction throughout the optimization process. Cadaver experiments were conducted on a cone-beam CT testbench emulating a lung nodule surveillance scenario. Superior reconstruction accuracy and image quality were demonstrated using the dPIRPLE algorithm as compared to more traditional reconstruction methods including filtered backprojection, penalized-likelihood estimation (PLE), prior image penalized-likelihood estimation (PIPLE) without registration, and prior image penalized-likelihood estimation with rigid registration of a prior image (PIRPLE) over a wide range of sampling sparsity and exposure levels.

Deformable image registration with local rigidity constraints for cone-beam CT-guided spine surgery

Image-guided spine surgery (IGSS) is associated with reduced co-morbidity and improved surgical outcome. However, precise localization of target anatomy and adjacent nerves and vessels relative to planning information (e.g., device trajectories) can be challenged by anatomical deformation. Rigid registration alone fails to account for deformation associated with changes in spine curvature, and conventional deformable registration fails to account for rigidity of the vertebrae, causing unrealistic distortions in the registered image that can confound high-precision surgery. We developed and evaluated a deformable registration method capable of preserving rigidity of bones while resolving the deformation of surrounding soft tissue. The method aligns preoperative CT to intraoperative cone-beam CT (CBCT) using free-form deformation (FFD) with constraints on rigid body motion imposed according to a simple intensity threshold of bone intensities. The constraints enforced three properties of a rigid transformation-namely, constraints on affinity (AC), orthogonality (OC), and properness (PC). The method also incorporated an injectivity constraint (IC) to preserve topology. Physical experiments involving phantoms, an ovine spine, and a human cadaver as well as digital simulations were performed to evaluate the sensitivity to registration parameters, preservation of rigid body morphology, and overall registration accuracy of constrained FFD in comparison to conventional unconstrained FFD (uFFD) and Demons registration. FFD with orthogonality and injectivity constraints (denoted FFD+OC+IC) demonstrated improved performance compared to uFFD and Demons. Affinity and properness constraints offered little or no additional improvement. The FFD+OC+IC method preserved rigid body morphology at near-ideal values of zero dilatation (D = 0.05, compared to 0.39 and 0.56 for uFFD and Demons, respectively) and shear (S = 0.08, compared to 0.36 and 0.44 for uFFD and Demons, respectively). Target registration error (TRE) was similarly improved for FFD+OC+IC (0.7 mm), compared to 1.4 and 1.8 mm for uFFD and Demons. Results were validated in human cadaver studies using CT and CBCT images, with FFD+OC+IC providing excellent preservation of rigid morphology and equivalent or improved TRE. The approach therefore overcomes distortions intrinsic to uFFD and could better facilitate high-precision IGSS.

Patient-Specific Minimum-Dose Imaging Protocols for Statistical Image Reconstruction in C-arm Cone-Beam CT Using Correlated Noise Injection

Purpose

A new method for accurately portraying the impact of low-dose imaging techniques in C-arm cone-beam CT (CBCT) is presented and validated, allowing identification of minimum-dose protocols suitable to a given imaging task on a patient-specific basis in scenarios that require repeat intraoperative scans.

Method

To accurately simulate lower-dose techniques and account for object-dependent noise levels (x-ray quantum noise and detector electronics noise) and correlations (detector blur), noise of the proper magnitude and correlation was injected into the projections from an initial CBCT acquired at the beginning of a procedure. The resulting noisy projections were then reconstructed to yield low-dose preview (LDP) images that accurately depict the image quality at any level of reduced dose in both filtered backprojection and statistical image reconstruction. Validation studies were conducted on a mobile C-arm, with the noise injection method applied to images of an anthropomorphic head phantom and cadaveric torso across a range of lower-dose techniques.

Results

Comparison of preview and real CBCT images across a full range of techniques demonstrated accurate noise magnitude (within ~5%) and correlation (matching noise-power spectrum, NPS). Other image quality characteristics (e.g., spatial resolution, contrast, and artifacts associated with beam hardening and scatter) were also realistically presented at all levels of dose and across reconstruction methods, including statistical reconstruction.

Conclusion

Generating low-dose preview images for a broad range of protocols gives a useful method to select minimum-dose techniques that accounts for complex factors of imaging task, patient-specific anatomy, and observer preference. The ability to accurately simulate the influence of low-dose acquisition in statistical reconstruction provides an especially valuable means of identifying low-dose limits in a manner that does not rely on a model for the nonlinear reconstruction process or a model of observer performance.

3D-2D registration for surgical guidance: effect of projection view angles on registration accuracy

An algorithm for intensity-based 3D-2D registration of CT and x-ray projections is evaluated, specifically using single- or dual-projection views to provide 3D localization. The registration framework employs the gradient information similarity metric and covariance matrix adaptation evolution strategy to solve for the patient pose in six degrees of freedom. Registration performance was evaluated in an anthropomorphic phantom and cadaver, using C-arm projection views acquired at angular separation, Δθ, ranging from ∼0°-180° at variable C-arm magnification. Registration accuracy was assessed in terms of 2D projection distance error and 3D target registration error (TRE) and compared to that of an electromagnetic (EM) tracker. The results indicate that angular separation as small as Δθ ∼10°-20° achieved TRE <2 mm with 95% confidence, comparable or superior to that of the EM tracker. The method allows direct registration of preoperative CT and planning data to intraoperative fluoroscopy, providing 3D localization free from conventional limitations associated with external fiducial markers, stereotactic frames, trackers and manual registration.

Deformable image registration for cone-beam CT guided transoral robotic base-of-tongue surgery

Transoral robotic surgery (TORS) offers a minimally invasive approach to resection of base-of-tongue tumors. However, precise localization of the surgical target and adjacent critical structures can be challenged by the highly deformed intraoperative setup. We propose a deformable registration method using intraoperative cone-beam computed tomography (CBCT) to accurately align preoperative CT or MR images with the intraoperative scene. The registration method combines a Gaussian mixture (GM) model followed by a variation of the Demons algorithm. First, following segmentation of the volume of interest (i.e. volume of the tongue extending to the hyoid), a GM model is applied to surface point clouds for rigid initialization (GM rigid) followed by nonrigid deformation (GM nonrigid). Second, the registration is refined using the Demons algorithm applied to distance map transforms of the (GM-registered) preoperative image and intraoperative CBCT. Performance was evaluated in repeat cadaver studies (25 image pairs) in terms of target registration error (TRE), entropy correlation coefficient (ECC) and normalized pointwise mutual information (NPMI). Retraction of the tongue in the TORS operative setup induced gross deformation >30 mm. The mean TRE following the GM rigid, GM nonrigid and Demons steps was 4.6, 2.1 and 1.7 mm, respectively. The respective ECC was 0.57, 0.70 and 0.73, and NPMI was 0.46, 0.57 and 0.60. Registration accuracy was best across the superior aspect of the tongue and in proximity to the hyoid (by virtue of GM registration of surface points on these structures). The Demons step refined registration primarily in deeper portions of the tongue further from the surface and hyoid bone. Since the method does not use image intensities directly, it is suitable to multi-modality registration of preoperative CT or MR with intraoperative CBCT. Extending the 3D image registration to the fusion of image and planning data in stereo-endoscopic video is anticipated to support safer, high-precision base-of-tongue robotic surgery.

Growth responses of cartilage to static and dynamic compression

During skeletal development, growth, and maturation, gradual changes in the material properties and physical dimensions of cartilage occur under the influence of mechanical loading. The objective of the current study was to compare glycosaminoglyean biosynthesis and cell proliferation in fetal, calf, and adult bovine cartilage explants, isolated from defined depths from the articular surface, in response to controlled compressive loads. Mechanical testing confirmed that for all cartilage samples subjected to load, there was a marked time-averaged (static) compression, whereas the addition of dynamic load at a frequency of 0.01 Hz induced dynamic strain with amplitude and phase shift characteristics typical of stimuli that previously were found to be associated with stimulation of glycosaminoglycan synthesis. In metabolic studies, the application of static loading (84 kPa) for 24 hours inhibited glycosaminoglycan and deoxyribonucleic acid synthesis in all cultured cartilage samples. The superposition of dynamic loading (200 kPa, 0.01 Hz) induced a 20% stimulation of glycosaminoglycan biosynthesis in calf cartilage from the middle-deep zones over statically-loaded samples and an additional approximate 50% suppression of deoxyribonucleic acid synthesis in fetal and calf cartilage from the articular surface. These results indicate that synthesis of glycosaminoglycan and deoxyribonucleic acid, two distinct indices of cartilage growth, are regulated independently by mechanical loading and that cartilage responds differently to static and dynamic loading at different stages of maturation.

Arsenite induces oxidative DNA adducts and DNA-protein cross-links in mammalian cells

Arsenic is generally recognized as a nonmutagenic carcinogen because sodium arsenite induces DNA damage only at very high concentrations. In this study we demonstrate that arsenite concentrations above 0.25 microM induce DNA strand breaks in both human leukemia cells and Chinese hamster ovary cells. Therefore, DNA damage may be involved in arsenic-induced carcinogenesis. Formamidopyrimidine-DNA glycosylase and proteinase K greatly increased DNA strand breaks in arsenite-treated cells, providing evidence that a large portion of arsenite-induced DNA strand breaks come from excision of oxidative DNA adducts and DNA-protein cross-links. Because DNA strand breaks appear only temporarily during excision repair, the level of detectable DNA strand breaks will be low at any given time point. For this reason many previous studies have only detected low levels of DNA strand breaks. We also show that catalase, and inhibitors of calcium, nitric oxide synthase, superoxide dismutase, and myeloperoxidase, could modulate arsenite-induced DNA damage. We conclude that arsenite induces DNA adducts through calcium-mediated production of peroxynitrite, hypochlorous acid, and hydroxyl radicals.

A mannose selection system for production of fertile transgenic maize plants from protoplasts

 Maize (Zea mays L.) callus cultures cannot use mannose as a sole carbohydrate source, but can utilize fructose for that purpose. Phosphomannose isomerase (PMI) can convert mannose to fructose. Transgenic maize plants were obtained by selecting polyethylene glycol (PEG)-mediated transformed protoplasts on mannose (20 g/l) containing medium. Transgenic calluses and plants carrying the PMI structural gene, manA, were able to convert mannose to fructose. The PEG-mediated protoplast transformation frequency was 0.06%. Stable transformation was confirmed by PCR, PMI activity, germination tests, and by histochemical staining with 5-bromo-4-chloro-3-indolyl-β-D-glucuronide (X-Gluc). Stable integration of the transgenes into the maize genome was demonstrated in T₁ and T₂ plants. Results indicate that the mannose selection system can be used for maize PEG-mediated protoplast transformation.

In vivo antitumor activity and induction of insulin-like growth factor-1-resistant apoptosis by SC-alphaalphadelta9

We previously showed that SC-alphaalphadelta9 (4-(benzyl-(2-[(2, 5-diphenyl-oxazole-4-carbonyl)-amino]-ethyl)-carbamoyl)-2-decanoylami no butyric acid) is a novel antiphosphatase agent that selectively inhibits the growth of transformed cells in culture and affects elements of insulin-like growth factor-1 (IGF-1) signaling. We now show that SC-alphaalphadelta9 induces IGF-1-resistant apoptosis and kills tumor cells in vivo. In cultured murine 32D cells, SC-alphaalphadelta9 induced concentration-dependent apoptosis that was blocked by ectopic Bcl-2 expression. No apoptosis was detected in 32D cells treated with the congener SC-alpha109, which lacks the ability to disrupt IGF-1 signaling. After interleukin-3 withdrawal or etoposide treatment, exogenous IGF-1 prevented apoptosis and elevated levels of Cdc2, a biochemical indicator of a functional IGF-1 receptor pathway. In contrast, exogenous IGF-1 did not prevent apoptosis or loss of Cdc2 expression caused by SC-alphaalphadelta9. Furthermore, IGF-1 receptor overexpression failed to protect cells against SC-alphaalphadelta9-induced apoptosis. Kinetic analyses demonstrated that Cdc2 down-regulation after SC-alphaalphadelta9 treatment preceded both apoptosis and loss of the IGF-1 receptor, indicating that loss of Cdc2 was a direct effect of SC-alphaalphadelta9 treatment and not secondary to cell death. IGF-1 receptor autophosphorylation studies indicated that SC-alphaalphadelta9 did not interact directly with the IGF-1 receptor nor bind to the growth factor itself, suggesting a site of action distal to the IGF-1 receptor. In the SCCVII murine tumor model, a single i.p. injection of SC-alphaalphadelta9 caused a dose-dependent decrease in clonogenic cell survival. The IC(50) of SC-alphaalphadelta9 was 35 mg/kg, comparable to 25 mg/kg carboplatin. The ability to induce IGF-1-resistant apoptosis distinguishes SC-alphaalphadelta9 from other apoptosis-inducing agents and suggests compounds of this class deserve further study as potential anticancer agents.

Energy-dependent nuclear binding dictates metallothionein localization

Metallothioneins (MTs) are low molecular weight, stress-activated proteins that protect cells against heavy metals, oxidants, and some electrophilic drugs. Both nuclear and cytoplasmic MT phenotypes have been observed in cells even though MTs (6 kDa) are well below the size exclusion limit for diffusion through the nuclear envelope. To study the factors controlling MT subcellular partitioning, we covalently linked MTII to a fluorescent label and examined its subcellular distribution in response both to pharmacologic and physical perturbations. Fluorescent MTII localized to the nucleus of digitonin-permeabilized human SCC25 carcinoma cells, consistent with its endogenous distribution in these cells. Nuclear sequestration of the fluorescent MTII was inhibited by a 100-fold molar excess of unlabeled MTII and by wheat germ agglutinin, indicating a saturable binding mechanism and the involvement of one or more glycoproteins, respectively. Depletion of adenosine triphosphate (ATP) inhibited MTII nuclear localization, implying energy-dependent nuclear translocation or retention of MT. Neither chilling nor the absence of cytosolic extracts inhibited nuclear sequestration of MTII, supporting diffusion-based entry mechanism. In situ biochemical extractions of the nuclear MTII revealed at least two distinct binding activities. Collectively, these data indicate that MTII diffuses into the nucleus of SCC25 cells, where it is selectively and actively retained by nuclear binding factors, imparting its localization phenotype.

Diversity of metallothionein content and subcellular localization in the National Cancer Institute tumor panel

Metallothioneins (MTs) are major thiol-containing intracellular proteins that bind metals, are induced by stress, and have been implicated in resistance to drugs and heavy metals.

PURPOSE

To examine the hypothesis that the protective functionality of MT may be dictated by its subcellular localization.

METHODS

We analyzed the basal MT content in 53 adherent cell lines of the National Cancer Institute (NCI) tumor panel and quantified the nuclear/cytoplasmic distribution of MT using confocal laser scanning microscopy and a recently described immunofluorescence-based algorithm.

RESULTS

Among these cell types we found a 400-fold range in the basal MT levels and a tenfold range in the ratio of the nuclear to cytoplasmic MT immunostaining that was independent of basal MT content. Total MT levels and nuclear/cytoplasmic distribution were independent of total glutathione content, suggesting autonomous regulation of these protective protein and nonprotein thiol pools. Approximately 50% (29/53) of the cell lines had a greater nuclear than cytoplasmic MT density and were defined as having a karyophilic phenotype. Tissue specificity of MT localization was seen with breast cancer cell lines, which were cytoplasmophilic, whereas prostate-derived cells were karyophilic. Among the 25000 unrestricted compounds in the NCI database, we detected a correlation between total basal MT levels and resistance to CdCl2, four Pt- and two Cu-containing compounds. High nuclear/cytoplasmic MT values correlated with resistance to six Cu-, six Pb-, and one Zn-containing compounds.

CONCLUSIONS

These results demonstrated significant diversity in MT content and subcellular localization in human tumor cells. Moreover, both basal MT levels and subcellular distribution appeared to be determinants of cellular responsiveness to metal-containing compounds.

Transcranial Doppler ultrasonography in neurosurgery: effects of intracranial tumour on right middle cerebral artery flow velocity during induction of anaesthesia

The right middle cerebral artery flow velocity (MCAFV) was measured by transcranial Doppler ultrasonography in neurosurgical patients with and without intracranial tumours during anaesthetic induction and endotracheal intubation. With institutional and patient consent, 20 non-tumour and 85 tumour-bearing neurosurgical patients were enlisted. The right middle cerebral artery was insonated with a pulsed-wave range-gated transcranial Doppler at 2 MHz, and MCAFV was recorded via a video graphics printer. The mean MCAFV, pulsatility index, use of anaesthetic drugs, heart rate, mean arterial pressure, and endtidal CO2 were recorded on preinduction, postinduction, intubation, and 90 to 180 s postintubation. There was no demographic, systemic haemodynamic, or anaesthetic difference between groups except for a predominance of women in the tumour group. In all patients, mean arterial pressure and MCAFV demonstrated with time a significant decrease with anaesthetic induction, increase with endotracheal intubation, and decrease post intubation. The right MCAFV was significantly higher in both tumour and right-sided tumour patients compared to non-tumour patients. There was no difference in left-sided tumour patients compared to non-tumour patients. These data indicate that intracranial tumours have cerebrovascular effects, causing either hyperaemia or vasoconstriction, and that the effects of anaesthetic induction and intubation agree with previously reported effects on cerebral blood flow and intracranial pressure.

The number and distribution of incompatibility factors in natural populations of Pleurotus ostreatus and Pleurotus sapidus

Pairings of single-spore isolates from different basidiocarps were made to examine the numbers and distributions of incompatibility factors in the tetrapolar basidiomycetes Pleurotus ostreatus and Pleurotus sapidus. These factors do not appear to be randomly distributed, with multiple basidiocarps on a single tree or log arising from a single mycelium, multiple basidiocarps on a single tree or log sharing a single common monokaryotic parent, and a tendency toward spatial clustering of factors even when multiple basidiocarps from the same tree or log are excluded from the analyses. For one 30-km2 collection area, the estimated numbers of A and B factors in the P. ostreatus population were 126 and 354, respectively, yielding an estimated outbreeding efficiency of 0.99. Estimated outbreeding efficiencies were quite high [Formula: see text] even in a sample taken from a very small area (0.09 m2), illustrating the ability of the tetrapolar mating system to simultaneously prevent self mating and minimize the number of incompatible matings. Key words: Basidiomycotina, fungi, mating system, population genetics.

[Pharmacognostic studies on the peel of Citrus reticulata Blanco cv. zhangshuensis and Citrus reticulata Blanco Var. kinokuni (Tanaka) H. H. Hu produced in Jiangxi]

Pharmacognostical studies on the peel of Citrus reticulata cv. zhangshuensis and Citrus reticulata var. kinokuni have been carried out in comparison with four crude drugs of Chenpi. Information on the research of resources of these two drugs is provided.

Callus induction and plant regeneration from maize mature embryos

Calli were induced from mature embryos of maize (Zea mays L.) inbred lines A632, B73 and Mol7 on MS medium supplemented with 1-2 mg/1 2,4-dichlorophenoxyacetic acid. Callus induction frequency ranged from 23-100%, with Mol7 having the highest frequency. Plants were regenerated from 4-5% of the B73 and Mol7 explants. Embryogenic and organogenic calli of B73 were maintained for more than two and one half years without losing regenerability. Of 95 regenerated plants, only one R0 plant with abnormal pollen was detected, and no morphological variants were observed in the R1 progeny.

Detection of antibodies to tetanus toxoid: comparison of a direct haemagglutination method with a radioimmunoassay

Two methods of detecting antibodies to tetanus toxoid were compared, a radioimmunoassay (RIA) employing radiolabelled staphylococcal protein A and a direct haemagglutination (HA) method employing sheep erythrocytes coupled to tetanus toxoid with chromic chloride. These were shown to have a similarly high specificity with the HA method showing slightly higher sensitivity. Haemagglutination offers several additional advantages in terms of simplicity, low cost and less requirement for specialised equipment. The assays were also used to demonstrate a transient IgM response after repeated booster injections with absorbed toxin given to seropositive individuals, and these antibodies were found to be protective in biological tests.