Epidemiological investigation of Entamoeba in wild rhesus macaques in China: A novel ribosomal lineage and genetic differentiation of Entamoeba nuttalli

Wild rhesus macaques are a potential source of zoonotic parasites for humans, and Entamoeba spp. are common intestinal parasites. To investigate the prevalence of Entamoeba in wild rhesus macaques in China and explore the genetic differentiation of the potentially pathogenic species Entamoeba nuttalli, a total of 276 fecal samples from five populations at high altitudes (HAG, 2,800-4,100 m above sea level) and four populations at low altitudes (LAG, 5-1,000 m above sea level) were collected. PCR methods based on the ssrRNA gene were used to detect Entamoeba infection. Genotyping of E. nuttalli was performed based on six tRNA-linked short tandem repeat (STR) loci for further genetic analyses. The results revealed that Entamoeba infection (69.2%) was common in wild rhesus macaques in China, especially in LAG which had a significantly higher prevalence rate than that in HAG (P < 0.001). Three zoonotic species were identified: Entamoeba chattoni (60.9%) was the most prevalent species and distributed in all the populations, followed by Entamoeba coli (33.3%) and Entamoeba nuttalli (17.4%). In addition, a novel Entamoeba ribosomal lineage named RL13 (22.8%) was identified, and phylogenetic analysis revealed a close genetic relationship between RL13 and Entamoeba. hartmanni. Genotyping of E. nuttalli obtained 24 genotypes from five populations and further analysis showed E. nuttalli had a high degree of genetic differentiation (FST > 0.25, Nm < 1) between the host populations. The result of analysis of molecular variance (AMOVA) revealed that observed genetic differences mainly originate from differences among populations (FST = 0.91). Meanwhile, the phylogenetic tree showed that these genotypes of E. nuttalli were clustered according to geographical populations, indicating a significant phylogeographic distribution pattern. Considering the potential pathogenicity of E. nuttalli, attention should be paid to its risk of zoonotic transmission.

Clinical significance of extrathyroidal extension to major vessels in papillary thyroid carcinoma

PURPOSE

Gross extrathyroidal extension (gETE) into major vessel is considered the most advanced stage of the locally advanced papillary thyroid cancer (PTC). Surgical intervention may not benefit some patients at this disease stage or even result in intraoperative death due to massive hemorrhage; however, it is still considered an effective strategy for most cases. The lack of description for this challenging invasion in PTC warrants detailed characterization of its pattern, risk factors, optimal surgical method, and prognostic value.

METHODS

In total, 3127 patients diagnosed as having PTC were enrolled and categorized into two the following groups, namely the major vessel invasion (MVI) group (n = 30) and the control group (n = 3097). Data regarding clinicopathological and demographic characteristics, vascular invasion sites, postoperative complications, locoregional recurrence, distant metastasis, and surgical strategies were collected. Predictive disease-free survival (DFS) was also compared between the two groups.

RESULTS

MVI was independently associated with invasion of the esophageal extension, age < 55 years, tumor size > 1 cm, lateral lymph node metastasis, and distant metastasis (P = 0.00; P = 0.01; 0.05; P = 0.00; P = 0.00, respectively). The difference in the predictive DFS between the two groups was significant (P = 0.00), and the difference remained significant even in patients with ETE when compared with patients without ETE (P = 0.00). Additionally, predictive DFS did not differ significantly between patients who received vessel repairment and those who received vessel resection (P = 0.28).

CONCLUSIONS

This study first characterized the gross MVI pattern exhibited by PTC and the risk factors for MVI. Additionally, it demonstrated the DFS of patients with PTC. Extensive gross MVI significantly worsened the biological characteristics of PTC. Regardless of the high risk and difficulty of the operation, patients still benefited from the surgical intervention, and vessel repairment may be the optimal surgical strategy.

MiR-590 suppresses the progression of non-small cell lung cancer by regulating YAP1 and Wnt/β-catenin signaling

OBJECTIVE

Accumulating evidence has been revealed that miR-590 is involved in the progression and carcinogenesis of various cancers. However, the molecular mechanism of miR-590 in non-small-cell lung cancer (NSCLC) remains unclear.

METHODS

Quantitative reverse transcription-PCR (qRT-PCR), western blot, MTT, and transwell assay were applied to investigate the functional role of miR-590 in this study. Dual luciferase reporter assay was utilized to investigate the interaction between YAP1 and miR-590 expression. Cells transfected with miR-590 mimic or inhibitor were subjected to western blot to investigate the role of Wnt/β-catenin signaling in NSCLC modulated by miR-590.

RESULTS

MiR-590 was down-regulated in NSCLC tissues and cells. Kaplan-Meier analysis found that the higher expression of miR-590 in NSCLC patients, the more improved survival rate of NSCLC patients. Over-expression of miR-590 inhibited NSCLC cell proliferation, migration, and invasion. Moreover, increasing miR-590 suppressed Yes-associated protein 1 (YAP1) expression and inhibited the Wnt/β-catenin pathway in NSCLC cells. Furthermore, miR-590 was negatively correlated with YAP1 expression.

CONCLUSION

These findings demonstrated that the miR-590/YAP1 axis exerted an important role in the progression of NSCLC, suggesting that miR-590 might be the appealing prognostic marker for NSCLC treatment.

Thermodynamics of Pb(ii) and Zn(ii) binding to MT-3, a neurologically important metallothionein

Isothermal titration calorimetry (ITC) was used to quantify the thermodynamics of Pb(2+) and Zn(2+) binding to metallothionein-3 (MT-3). Pb(2+) binds to zinc-replete Zn7MT-3 displacing each zinc ion with a similar change in free energy (ΔG) and enthalpy (ΔH). EDTA chelation measurements of Zn7MT-3 and Pb7MT-3 reveal that both metal ions are extracted in a tri-phasic process, indicating that they bind to the protein in three populations with different binding thermodynamics. Metal binding is entropically favoured, with an enthalpic penalty that reflects the enthalpic cost of cysteine deprotonation accompanying thiolate ligation of the metal ions. These data indicate that Pb(2+) binding to both apo MT-3 and Zn7MT-3 is thermodynamically favourable, and implicate MT-3 in neuronal lead biochemistry.

Clinical and manometric characteristics of patients with Parkinson's disease and esophageal symptoms

Dysphagia is a common problem in patients with Parkinson's disease (PD); its etiology is multifactorial and its management is challenging. In this retrospective cohort analysis using prospectively collected data, we aimed to objectively characterize dysphagia and/or other esophageal symptoms in patients with PD, assess the prevalence of outflow obstruction as well as major or minor disorders of esophageal peristalsis leading to impaired esophageal clearance and highlight objective parameters that can help in the current management algorithm. Thirty-three consecutive patients with PD presenting with dysphagia, odynophagia, heartburn, regurgitation, chest pain, and weight loss underwent clinical and functional evaluation by high-resolution manometry (HRM). Esophagogastric junction (EGJ) outflow obstruction and major as well as minor disorders of peristalsis were then assessed using the Chicago classification (v3). Thirty-three PD patients with esophageal symptoms were enrolled in the study; 12 of them reported weight loss that was considered as potentially reflecting underlying esophageal dysfunction. The median age of the patients was 70 years (range: 53-89 years), 24 (75%) were men. The majority (62%) experienced dysphagia, likely contributing to weight loss in 41% of patients. Odynophagia was rare (6%) while GER symptoms, such as heartburn, regurgitation, and chest pain were noted in 37%, 31%, and 28% of patients, respectively. Using the hierarchy of the Chicago classification, 12 patients (39%) exhibited EGJ outflow obstruction, 16 (48%) diffuse esophageal spasm (DES), 18 (55%), ineffective esophageal peristalsis (IEM), 16 (48%) fragmented peristalsis, and only 2 patients (6%) had normal HRM tracings. There were no patients with HRM features of achalasia. Dysphagia is common in patients with PD and is associated with a high prevalence of underlying motility disturbances as identified by HRM. The exact impact of these motility abnormalities on symptom induction and their role in influencing clinical management are unclear and will require further study.

Abstract P3-04-25: Role of H19, a long non-coding RNA, in development of resistance to endocrine therapy in breast cancer cells

Introduction:

Majority of breast cancer tumors are Estrogen receptor positive (ER+) where antiestrogen therapies (endocrine therapies) are the best therapeutic strategy to treat this type of tumors. However, eventually over 30% of patients will develop resistance to endocrine therapies resulting in disease relapse. We recently showed that the long noncoding RNA, H19, is an estrogen target gene that plays a significant role in estrogen-induced proliferation of the normal and malignant ER+ cells. We therefore hypothesize that H19 expression is also important to the proliferation of endocrine therapy resistant cells. In this study, we examined if estrogen-independent H19 expression is important to the development of endocrine therapy resistance.

Objective:

The overall objective of this project is to use therapy sensitive (MCF-7) and therapy-resistant (LCC9) breast cancer cells as model systems to examine the role of long non-coding RNA H19 in development and maintenance of resistance to endocrine therapy.

Methodology and Results:

We examined the expression of H19 in ER+ breast cancer cells (MCF7) that under the selective pressure of fulvesterant (ICI, ER down regulator) acquire resistance to ICI. We observed that while H19 expression was initially decreased as expected, its expression subsequently increased in the ICI-resistant MCF7 cells. Interestingly, H19 knockdown in MCF7 cells significantly decrease their proliferation as determined by Flowcytometry and made them more sensitive to ICI. We also examined H19 expression in the ICI-resistant LCC9 cells and found that ICI treatment increased H19 expression. Interestingly, H19 knockdown in the LCC9 cells decreased their proliferation and surprisingly made them sensitive to ICI treatment. Previous observations indicate that NOTCH4 receptor (NR4) may be involved in endocrine therapy resistance. Interestingly we found that in presence of ICI, NR4 expression is increased and that forced activation of NR4 markedly increases H19 expression in LCC9 cells.

Conclusion:

Altogether these observations suggest that H19 plays an important role in the development of endocrine therapy resistance and further our understanding of the cellular and molecular mechanisms involved in endocrine therapy resistance. These and similar studies could potentially lead to the development of new therapies to treat therapy resistant tumor cells. Further experiments would reveal if signalling pathways that regulate H19 expression independent of estrogen are useful therapies against endocrine therapy resistant tumors.

Citation Format: Basak P, Chatterjee S, Bhat V, Jin H, Su A, Murphy LC, Raouf A. Role of H19, a long non-coding RNA, in development of resistance to endocrine therapy in breast cancer cells [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-04-25.

Epidemiology, diagnosis, surgical treatment and prognosis of the pancreatic neuroendocrine tumors: Report of 125 patients from one single center

OBJECTIVE

The objective of the following study is to summarize the epidemiology of pancreatic neuroendocrine tumors (p-NETs) in our single institution, analyze the diagnostic characteristics, share the experience of surgical treatments and discuss the prognostic factors.

METHODS

A retrospective collection and analysis of clinical data of 125 patients with p-NETs which were pathologically confirmed in our hospital from January 2002 to December 2012.

RESULTS

A total of 125 patients of which 52 were males and 73 were females. Totally 92 patients had functional p-NETs, while non-functional p-NETs were diagnosed in 33 patients. The most common operative procedures performed were local resection of pancreatic tumor (47.2%), followed by distal pancreatectomy (29.6%). Thirty patients (28%) had post-operative complications, the most common of which was pancreatic fistula (22.4%). The overall survival rate at 5 years was 68.4%. The 5-year survival rate for patients with functional tumors was 75.1%, compared with 50.0% for those with non-functional tumors (P = 0.021). The survival time of patients with R0 resection was statistically longer than that of patients with Not R0 resection (P < 0.005). In univariate analysis, the most powerful predictors of poor outcome were gender, age, tumor size, functional status, surgical margins, lymph node invasion and distant metastasis. However only surgical margin and distant metastasis were significant predictors in multivariate analysis (P = 0.001, 0.047, respectively).

CONCLUSION

p-NETs are an uncommon and heterogeneous group of tumors, with a rising incidence. Surgery is the most effective treatment. Surgical margin and distant metastasis were the most significant prognostic factors. Radical resection should be taken more into considerations.

Expression of CD80 on cultured neonatal mice cardiomyocytes and attenuation of cytotoxic T lymphocyte-mediated lysis

Transplantation of cultured heterogeneous proliferating cardiomyocytes is a promising therapeutic approach for the treatment of the damage cardiac area resulting from myocardial infarction. However, the chances of recipient rejection are high. How to reduce the immunogenicity of heterogeneous cardiomyocytes and attenuate immune rejection is one of the key stumbling blocks in the application of these cells. In this study, we determined that cultured neonatal cardiomyocytes from mice can express CD80 after culture. CD80 is one of the key costimulatory molecules. Most scholars believe that the main function of CD80 is to activate and boost immune rejection. However, recent studies have shown that CD80 may primarily bind with CTLA-4 and inhibit the immune response. To further study how CD80 worked on these cells, a cytotoxic T-lymphocyte (CTL) assay was performed. The results showed that activated allogenic CTLs lysed cultured cardiomyocytes lacking CD80 expression, but they did not efficiently lyse cardiomyocytes expressing CD80. If we blocked the CD80 with anti-CD80 monoclonal antibody (mAb), the percentages of cardiomyocytes lysis were significantly increased. CD80 can bind CD28, CTLA-4, PD-L1, and even B7-H1, but the main ligands are CD28 and CTLA-4. Thus, we blocked the two ligands separately. When anti-CTLA-4 mAb was applied, the percentages of cardiomyocytes lysis were significantly increased, but when anti-CD28 mAb was applied, the percentages of cell lysis were the same as the intact control. The results indicated that CD80 and CTLA-4 played an important role on the attenuation of CTL-mediated lysis. To our knowledge, this study, for the first time, proves that cardiomyocytes can express CD80 and this expression pattern can resist CTL-mediated lysis through CTLA-4 pathway. The results could have implications in efforts to improve therapeutic strategies for cardiomyocyte transplantation.

Comparison of late gastrointestinal and genitourinary toxicity of prostate cancer patients undergoing intensity-modulated versus conventional radiotherapy using localized fields

To compare late genitourinary (GU) and gastrointestinal (GI) toxicity of radiotherapy (RT) to localized fields for prostate cancer delivered using intensity-modulated RT (IMRT) versus conventional RT (ConvRT). The records of 461 patients were reviewed; 355 patients received IMRT and 106 received ConvRT. Late GU and GI toxicity were compared. Late GU toxicity rates were not significantly different (P=0.166); however, late GI toxicity rates were lower with IMRT (P=0.001). Regression analyses demonstrated that only IMRT use (P=0.006) predicted reduction in late GI toxicity but no factors correlated with late GU toxicity. IMRT did not influence late GU toxicity but was associated with a reduction of late GI toxicity over ConvRT.

Pre-impact lower extremity posture and brake pedal force predict foot and ankle forces during an automobile collision

BACKGROUND

The purpose of this study was to determine how a driver's foot and ankle forces during a frontal vehicle collision depend on initial lower extremity posture and brake pedal force.

METHOD OF APPROACH

A 2D musculoskeletal model with seven segments and six right-side muscle groups was used. A simulation of a three-second braking task found 3647 sets of muscle activation levels that resulted in stable braking postures with realistic pedal force. These activation patterns were then used in impact simulations where vehicle deceleration was applied and driver movements and foot and ankle forces were simulated. Peak rearfoot ground reaction force (F(RF)), peak Achilles tendon force (FAT), peak calcaneal force (F(CF)) and peak ankle joint force (F(AJ)) were calculated.

RESULTS

Peak forces during the impact simulation were 476 +/- 687 N (F(RF)), 2934 +/- 944 N (F(CF)) and 2449 +/- 918 N (F(AJ)). Many simulations resulted in force levels that could cause fractures. Multivariate quadratic regression determined that the pre-impact brake pedal force (PF), knee angle (KA) and heel distance (HD) explained 72% of the variance in peak FRF, 62% in peak F(CF) and 73% in peak F(AJ).

CONCLUSIONS

Foot and ankle forces during a collision depend on initial posture and pedal force. Braking postures with increased knee flexion, while keeping the seat position fixed, are associated with higher foot and ankle forces during a collision.

High dose antipsychotic use in schizophrenia: findings of the REAP (research on east Asia psychotropic prescriptions) study

BACKGROUND

High-dose antipsychotic regimes (defined as the prescription of more than 1000 chlorpromazine-equivalents milligrams of antipsychotic per day) in the management of patients with schizophrenia are not uncommon, but most reports are from western countries. Recent functional neuroimaging studies have found that the previous notion concerning the use of antipsychotic medication, especially in high doses, was unsupported and untenable.

METHODS

This international study examined the use of high dose antipsychotic medication and its clinical correlates in schizophrenia patients within six East Asian countries/territories.

RESULTS

Within the study group (n = 2399), 430 patients (17.9%) were prescribed high dose antipsychotics. Antipsychotic use varied significantly between countries, with Japan, Korea, and Singapore using higher doses than the other countries. High dose antipsychotic use was associated with younger age in Japan (p < 0.001), longer duration of admission (p < 0.001), duration of illness (p < 0.001, particularly in Korea and Taiwan), positive psychotic symptoms (p < 0.001, particularly in Japan and Korea), and aggression (p < 0.05, particularly in Japan), and also with a higher likelihood of extrapyramidal and autonomic adverse effects (p < 0.05, particularly in China). Country, younger age, the presence of delusions and disorganized speech, polypharmacy, and receiving depot medication but not atypical antipsychotic drugs were important predictors of high antipsychotic use.

CONCLUSIONS

This survey revealed that high antipsychotic dosing is not an uncommon practice in East Asia. It behooves the prescribing clinicians to constantly reevaluate the rationale for such a practice.

Reduced expression of small GTPases and hypermethylation of the folate binding protein gene in cisplatin-resistant cells

Reduced accumulation of cisplatin is the most consistent feature seen in cisplatin-resistant (CP-r) cells that are cross-resistant to other cytotoxic compounds, such as methotrexate. In this report, defective uptake of a broad range of compounds, including [¹⁴C]-carboplatin, [³H]MTX, [³H]folic acid (FA), [¹²⁵I]epidermal growth factor, ⁵⁹Fe, [³H]glucose, and [³H]proline, as well as ⁷³As⁵⁺ and ⁷³As³⁺, was detected in CP-r human hepatoma and epidermal carcinoma cells that we have previously shown are defective in fluid-phase endocytosis. Downregulation of several small GTPases, such as rab5, rac1, and rhoA, which regulate endocytosis, was found in CP-r cells. However, expression of an early endosomal protein and clathrin heavy chain was not changed, suggesting that the defective endocytic pathway is clathrin independent. Reduced expression of the cell surface protein, folate-binding protein (FBP), which is a carrier for the uptake of MTX, was also observed in the CP-r cells by confocal immunofluorescence microscopy and Real-Time PCR. Reactivation of the silenced FBP gene in the CP-r cells by a DNA demethylation agent, 2-deoxy-5-aza-cytidine (DAC) demonstrates that hypermethylation occurred in the CP-r cells. The uptake of [¹⁴C]carboplatin, [³H]FA, and [³H]MTX increased in an early stage CP-r cell line (KB-CP1) after treatment with DAC. Both a defective endocytic pathway and DNA hypermethylation resulting in the downregulation of small regulatory GTPases and cell surface receptors contribute to the reduced accumulation of a broad range of compounds in CP-r cells.

Reduced expression of small GTPases and hypermethylation of the folate binding protein gene in cisplatin-resistant cells

Reduced accumulation of cisplatin is the most consistent feature seen in cisplatin-resistant (CP-r) cells that are cross-resistant to other cytotoxic compounds, such as methotrexate. In this report, defective uptake of a broad range of compounds, including [(14)C]-carboplatin, [(3)H]MTX, [(3)H]folic acid (FA), [(125)I]epidermal growth factor, (59)Fe, [(3)H]glucose, and [(3)H]proline, as well as (73)As(5+) and (73)As(3+), was detected in CP-r human hepatoma and epidermal carcinoma cells that we have previously shown are defective in fluid-phase endocytosis. Downregulation of several small GTPases, such as rab5, rac1, and rhoA, which regulate endocytosis, was found in CP-r cells. However, expression of an early endosomal protein and clathrin heavy chain was not changed, suggesting that the defective endocytic pathway is clathrin independent. Reduced expression of the cell surface protein, folate-binding protein (FBP), which is a carrier for the uptake of MTX, was also observed in the CP-r cells by confocal immunofluorescence microscopy and Real-Time PCR. Reactivation of the silenced FBP gene in the CP-r cells by a DNA demethylation agent, 2-deoxy-5-aza-cytidine (DAC) demonstrates that hypermethylation occurred in the CP-r cells. The uptake of [(14)C]carboplatin, [(3)H]FA, and [(3)H]MTX increased in an early stage CP-r cell line (KB-CP1) after treatment with DAC. Both a defective endocytic pathway and DNA hypermethylation resulting in the downregulation of small regulatory GTPases and cell surface receptors contribute to the reduced accumulation of a broad range of compounds in CP-r cells.

Foot and ankle forces during an automobile collision: the influence of muscles

Muscles have a potentially important effect on lower extremity injuries during an automobile collision. Computational modeling can be a powerful tool to predict these effects and develop protective interventions. Our purpose was to determine how muscles influence peak foot and ankle forces during an automobile collision. A 2-D bilateral musculoskeletal model was constructed with seven segments. Six muscle groups were included in the right lower extremity, each represented by a Hill muscle model. Vehicle deceleration data were applied as input and the resulting movements were simulated. Three models were evaluated: no muscles (NM), minimal muscle activation at a brake pedal force of 400 N (MN), and maximal muscle activation to simulate panic braking (MX). Muscle activation always resulted in large increases in peak joint force. Peak ankle joint force was greatest for MX (10120 N), yet this model also had the lowest peak rearfoot force (629 N). Peak force on the Achilles tendon was 4.5 times greater, during MX (6446 N) compared to MN (1430 N). We conclude that (1). external and internal forces are dependent on muscles, (2). muscle activation level could exacerbate axial loading injuries, (3). external and internal forces can be inversely related once muscle properties are included.

Development and Validation of a 3-D Model to Predict Knee Joint Loading During Dynamic Movement

The purpose of this study was to develop a subject-specific 3-D model of the lower extremity to predict neuromuscular control effects on 3-D knee joint loading during movements that can potentially cause injury to the anterior cruciate ligament (ACL) in the knee. The simulation consisted of a forward dynamic 3-D musculoskeletal model of the lower extremity, scaled to represent a specific subject. Inputs of the model were the initial position and velocity of the skeletal elements, and the muscle stimulation patterns. Outputs of the model were movement and ground reaction forces, as well as resultant 3-D forces and moments acting across the knee joint. An optimization method was established to find muscle stimulation patterns that best reproduced the subject’s movement and ground reaction forces during a sidestepping task. The optimized model produced movements and forces that were generally within one standard deviation of the measured subject data. Resultant knee joint loading variables extracted from the optimized model were comparable to those reported in the literature. The ability of the model to successfully predict the subject’s response to altered initial conditions was quantified and found acceptable for use of the model to investigate the effect of altered neuromuscular control on knee joint loading during sidestepping. Monte Carlo simulations (N=100,000) using randomly perturbed initial kinematic conditions, based on the subject’s variability, resulted in peak anterior force, valgus torque and internal torque values of 378 N, 94 Nm and 71 Nm, respectively, large enough to cause ACL rupture. We conclude that the procedures described in this paper were successful in creating valid simulations of normal movement, and in simulating injuries that are caused by perturbed neuromuscular control.

Horses damp the spring in their step

The muscular work of galloping in horses is halved by storing and returning elastic strain energy in spring-like muscle-tendon units.These make the legs act like a child's pogo stick that is tuned to stretch and recoil at 2.5 strides per second. This mechanism is optimized by unique musculoskeletal adaptations: the digital flexor muscles have extremely short fibres and significant passive properties, whereas the tendons are very long and span several joints. Length change occurs by a stretching of the spring-like digital flexor tendons rather than through energetically expensive length changes in the muscle. Despite being apparently redundant for such a mechanism, the muscle fibres in the digital flexors are well developed. Here we show that the mechanical arrangement of the elastic leg permits it to vibrate at a higher frequency of 30-40 Hz that could cause fatigue damage to tendon and bone. Furthermore, we show that the digital flexor muscles have minimal ability to contribute to or regulate significantly the 2.5-Hz cycle of movement, but are ideally arranged to damp these high-frequency oscillations in the limb.

A screening method for knee trauma

RATIONALE AND OBJECTIVES

The authors performed this study to evaluate whether any one conventional radiographic view is sufficient as a screening method in the detection of acute knee trauma.

MATERIALS AND METHODS

The authors prospectively assessed the efficacy of a single conventional radiograph of the knee in the detection of signs of knee fractures in 214 consecutive adults with acute knee trauma. The evaluated efficacy parameters included specificity, sensitivity, negative predictive value (NPV), and positive predictive value. The percentage reduction in the need for additional conventional radiographs was also calculated.

RESULTS

Fifty-three of the 214 patients (24.8%) had a knee fracture. The sensitivity of the single lateral view in the detection of knee fractures was 100% (95% confidence interval [CI] = 94.3, 100). The lateral view of the traumatized knee was normal in 143 patients (66.8%). The probability of not having a fracture if the lateral view was normal (NPV) was also 100% (95% CI = 97.9, 100). The need for additional radiographs was reduced 67%.

CONCLUSION

A single lateral view as a screening tool for knee fractures has a very high sensitivity and NPV. Because more than 65% of the patients had a normal lateral view in this study, there can be a considerable amount of savings in terms of radiology services for these patients.

Designed protein G core variants fold to native-like structures: sequence selection by ORBIT tolerates variation in backbone specification

The solution structures of two computationally designed core variants of the beta 1 domain of streptococcal protein G (G beta 1) were solved by (1)H NMR methods to assess the robustness of amino acid sequence selection by the ORBIT protein design package under changes in protein backbone specification. One variant has mutations at three of 10 core positions and corresponds to minimal perturbations of the native G beta 1 backbone. The other, with mutations at six of 10 positions, was calculated for a backbone in which the separation between G beta 1's alpha-helix and beta-sheet was increased by 15% relative to native G beta 1. Exchange broadening of some resonances and the complete absence of others in spectra of the sixfold mutant bespeak conformational heterogeneity in this protein. The NMR data were sufficiently abundant, however, to generate structures of similar, moderately high quality for both variants. Both proteins adopt backbone structures similar to their target folds. Moreover, the sequence selection algorithm successfully predicted all core chi(1) angles in both variants, five of six chi(2) angles in the threefold mutant and four of seven chi(2) angles in the sixfold mutant. We conclude that ORBIT calculates sequences that fold specifically to a geometry close to the template, even when the template is moderately perturbed relative to a naturally occurring structure. There are apparently limits to the size of acceptable perturbations: In this study, the larger perturbation led to undesired dynamic behavior.

Lidocaine blockade of amygdala output in fear-conditioned rats reduces Fos expression in the ventrolateral periaqueductal gray

We showed recently that conditioned fear to context induces Fos expression in the ventrolateral periaqueductal gray [Neuroscience (1997) 78, 165-177]. Neurons in this region are thought to play an important role in the expression of freezing during conditioned fear. To test the possibility that this activation comes directly from the amygdala, we looked at changes in Fos expression after a unilateral blockade of the ventral amygdalofugal pathway with lidocaine. The pathway contains fibres originating from the central nucleus of the amygdala that project directly and mainly ipsilaterally to the ventrolateral periaqueductal gray. Conditioned fear was evoked by re-exposing rats to the same box in which they had previously received electric footshocks. The test re-exposure was preceded by a unilateral microinjection of lidocaine (2%, 0.5-1 microl; n = 20) or saline (n = 14). Lidocaine was also tested in non-conditioned animals (n = 13). The results show that, when lidocaine was microinjected in the medial part of the central nucleus of the amygdala or along the ventral amygdalofugal pathway of conditioned rats, fear-induced Fos expression in the ventrolateral periaqueductal gray was reduced on the side ipsilateral to the injection (up to 37% reduction in comparison to the contralateral side). Ipsilateral reductions were also observed with saline, but they were weaker (maximum of 27% reduction). Fos expression remained low on both sides in the non-fear-conditioned animals injected with lidocaine. Finally, although freezing was only partly reduced in the conditioned animals unilaterally injected with lidocaine, it was significantly correlated to the ipsilateral reduction in Fos expression. This study provides direct evidence that the projection from the central nucleus of the amygdala to the ventrolateral periaqueductal gray is activated during fear and that it contributes to the Fos response of the ventrolateral periaqueductal gray.

Rheumatoid nodule of the foot: MRI appearances mimicking an indeterminate soft tissue mass

Subcutaneous rheumatoid nodules occur commonly in advanced cases of rheumatoid arthritis, but only rarely appear in the feet. We present a case of a subcutaneous rheumatoid nodule arising in the heel pad of a 68-year-old man with a long history of rheumatoid arthritis, along with a review of the literature. The appearance of the mass on MRI is illustrated and correlated with the histologic findings. The MRI appearance of a subcutaneous rheumatoid nodule is that of a nonspecific ill-defined mass with long T1- and long T2-relaxation times. A differential diagnosis for similar appearing masses is offered.

Coupling backbone flexibility and amino acid sequence selection in protein design

Using a protein design algorithm that considers side-chain packing quantitatively, the effect of explicit backbone motion on the selection of amino acids in protein design was assessed in the core of the streptococcal protein G beta 1 domain (G beta 1). Concerted backbone motion was introduced by varying G beta 1's supersecondary structure parameter values. The stability and structural flexibility of seven of the redesigned proteins were determined experimentally and showed that core variants containing as many as 6 of 10 possible mutations retain native-like properties. This result demonstrates that backbone flexibility can be combined explicitly with amino acid side-chain selection and that the selection algorithm is sufficiently robust to tolerate perturbations as large as 15% of G beta 1's native supersecondary structure parameter values.

A multi-substrate single-file model for ion-coupled transporters

Ion-coupled transporters are simulated by a model that differs from contemporary alternating-access schemes. Beginning with concepts derived from multi-ion pores, the model assumes that substrates (both inorganic ions and small organic molecules) hop a) between the solutions and binding sites and b) between binding sites within a single-file pore. No two substrates can simultaneously occupy the same site. Rate constants for hopping can be increased both a) when substrates in two sites attract each other into a vacant site between them and b) when substrates in adjacent sites repel each other. Hopping rate constants for charged substrates are also modified by the membrane field. For a three-site model, simulated annealing yields parameters to fit steady-state measurements of flux coupling, transport-associated currents, and charge movements for the GABA transporter GAT1. The model then accounts for some GAT1 kinetic data as well. The model also yields parameters that describe the available data for the rat 5-HT transporter and for the rabbit Na(+)-glucose transporter. The simulations show that coupled fluxes and other aspects of ion transport can be explained by a model that includes local substrate-substrate interactions but no explicit global conformational changes.

Evaluation of various nitrogen supplements in starter diets for growing Holstein steers and their effects on ruminal bacterial fermentation in continuous culture

Concurrent in vivo and in vitro studies were conducted to evaluate urea (U), soybean meal (SBM), ground soybeans (RAW), extruded soybeans (ES) or extruded soybeans plus urea (ES + U) as primary supplemental N sources in starter diets for Holstein steers. Three groups of 48 Holstein steers each were fed five different starter diets to 181 kg BW in three experimental periods over 2 yr. Average daily gains were similar (P greater than .05) for steers fed ES + U (1.12 kg), ES (1.08 kg) and SBM (1.09 kg) but lower (P less than .05) for those fed U (1.00 kg) or RAW (.97 kg) diets. Feed/gain was similar (P greater than .05) for ES-fed steers vs those fed other diets except U. From 181 to 477 kg, all steers were fed the same diet. Steers fed the RAW starter diet had the lowest (P less than .05) ADG for the entire period. The starter diets were used as substrates for ruminal microbial metabolism in eight dual-flow continuous culture fermenters. True OM digestion was higher and NDF and ADF digestion was lower (P less than .05) for the ES + U diet than for the ES diet. Dietary protein degradation was lowest (P less than .05) for the ES diet (64.4%). Total bacterial N flow was higher (P less than .05) with the ES + U, SBM and U diets than with the ES diet. Lysine flow was higher (P less than .05) for the ES + U diet than for all other diets except ES. Results of these experiments indicate that ES as a protected ruminal escape N source with or without added urea did not improve steer performance above that obtained from SBM in starter diets.