bluuebunny/crossref_metadata_2025 huggingface dataset:
Automatic Camera Calibration Using Pattern Detection for Vision-Based Speed Sensing
Authors: Kanhere Neeraj K. , Birchfield Stanley T. , Sarasua Wayne A.
Published: January 2009

Vision-based automatic traffic monitoring systems require a calibrated camera to measure the speeds of tracked vehicles. Typically this calibration is done by hand. An automatic technique was developed to calibrate the camera for typical viewpoints on highways using a real-time boosted cascade vehicle detector (BCVD). Image processing is used to estimate the two vanishing points, from which the camera height, focal length, and pan and tilt angles are calculated. The key contribution of the proposed approach is its applicability to a wide variety of environmental conditions. The technique does not rely on background subtraction, nor does it require scene-specific features such as pavement markings. As a result, it is unaffected by the presence of shadows, adverse weather conditions, headlight reflections, lack of ambient light, or spillover caused by low-mounted cameras. Speed estimation within 10% of ground truth is shown for sequences obtained during daylight, nighttime, and rain, and including shadows and severe occlusion.
Evaluating Traveler Information Effects on Commercial and Noncommercial Users
Authors: Pan Xiaohong , Khattak Asad J.
Published: January 2009

Incidents often account for nearly half of traffic congestion in urban areas and add uncertainty to transportation networks. The costs of incident-induced congestion, often in the form of delays, are borne by motorists and commercial carriers or associated businesses. In fact, a higher burden is borne by commercial carriers, given their higher costs and value of time. Dynamic traveler information about incidents disseminated through electronic media can benefit users. The extent of benefits associated with dynamic traveler information and whether network delays increase or decline were explored when (a) travelers can observe incidents, (b) commercial truck percentages increase in traffic, (c) truck drivers divert to alternate routes in the same way motorists do, as opposed to having lower diversion rates, and (d) commercial trucks have a higher value of time compared with passenger vehicles. With a behavioral route diversion model, the movement of commercial trucks and passenger vehicles in a simple transportation network was simulated. The results show how dynamic traveler information may or may not benefit commercial and noncommercial users under different scenarios.
Simple Mixed Reality Infrastructure for Experimental Analysis of Route Choice Behavior
Authors: Talaat Hoda , Masoud Mohamed , Abdulhai Baher
Published: January 2009

Microscopic traffic simulation models offer virtual reproduction of full-scale traffic networks with individual vehicle and driver resolution. However, relevant behavioral aspects, such as route-choice behavior, are based on some theoretical assumptions. Alternatively, driving simulators allow for direct testing of real subjects. However, the virtual driving environment is typically a fairly rudimentary representation of the road network and traffic conditions, focusing on the immediate surroundings of the test vehicle. As such, both tools were integrated to create a mixed reality traffic analysis environment. The objective is to enhance the credibility of in-lab-simulated route-choice experiments under various intelligent transportation system applications. The mixed reality system allows a human subject to “drive” a vehicle in a microscopic traffic simulation model of an actual physical network. An externally controlled driving capability was integrated into the widely used Quadstone Paramics microscopic traffic simulator. The developed mixed reality platform was used at the Toronto (Canada) Intelligent Transportation System Centre to test subjects while driving in a simulated model of a main downtown Toronto corridor. Drivers were given descriptive and prescriptive traffic information while their reactions were monitored. For comparative purposes, they were also tested using a more classical map-based point-and-click route-choice procedure. Results of the analysis highlight the potential of the developed mixed reality platform to enhance the realism of in-lab-simulated route-choice experiments and hence improve the credibility of collected data. Both the virtual reproduction of the choice environment and the tangible consequences of choice decisions contribute to an enhanced experimental environment.
A new approach for observing cerebral cisterns and ventricles via a percutaneous lumbosacral route by using fine, flexible fiberscopes
Authors: Shimoji Koki , Ogura Mai , Gamou Sanae , Yunokawa Seki , Sakamoto Hidetoshi , Fukuda Satoru , Morita Shigeho
Published: January 2009

Object

To establish a new method for the diagnosis of central nervous system diseases, the authors visualized the cerebral cisterns and ventricles via a percutaneous lumbosacral route by using newly developed fine, flexible fiberscopes.

Methods

Fine, flexible fiberscopes, 0.9 and 1.4 mm in diameter, were introduced up to the cerebral cisterns and ventricles through a percutaneous lumbosacral route in awake patients with chronic headache and/or neck pain or those undergoing spinal surgery and in whom MR imaging did not disclose any particular abnormalities in the brain. A lumbosacral subarachnoid puncture was made with a modified method of a continuous epidural block.

Results

In 25 of 31 patients tested, the cerebellomedullary and/or pontine/interpeduncular cisterns were easily and safely reached, and the brainstem structures were visualized. Advancement of the fiberscope beyond the spinal level was abandoned in 6 patients with adhesive spinal arachnoiditis, because the fiberscopes encountered resistance seemingly caused by arachnoid adhesions. Further advancement of the fiberscopes up to the fourth and third ventricles was successfully achieved in 2 patients. A number of arachnoid filaments were found in the cerebellomedullary cistern in 4 patients: 2 with chronic spinal arachnoiditis, 1 with a spinal arachnoid cyst, and 1 with posttraumatic pain syndrome. None of the patients reported pain or any major complication except a postspinal headache and light fever, which were encountered in 4 and 1 patient, respectively.

Conclusions

The approach to the supraspinal structures via the lumbosacral route by using a fine, flexible fiberscope may provide a new, minimally invasive, and safe way to observe the cerebral cisterns and/or brainstem regions.
Outcome after hemorrhage following Gamma Knife surgery for cerebral arteriovenous malformations
Authors: Kasliwal Manish Kumar , Kale Shashank Sharad , Gupta Aditya , Kiran Narayanam Anantha Sai , Sharma Manish Singh , Sharma Bhawani Shanker , Mahapatra Ashok K.
Published: January 2009

Object

Although the effects of Gamma Knife surgery (GKS) on the risk of hemorrhage are poorly understood, a certain subset of patients does suffer bleeding after GKS. This study was undertaken to analyze the outcome of patients sustaining hemorrhage after GKS; it is the most feared complication of radiosurgical management of cerebral arteriovenous malformations (AVMs).

Methods

Between May 1997 and June 2006, 494 cerebral AVMs in 489 patients were treated using a Leksell Gamma Knife Model B, and follow-up evaluations were conducted until June 2007 at the All India Institute of Medical Sciences in New Delhi. Fourteen patients who sustained a hemorrhage after GKS formed the study group. In most of these patients conservative management was chosen.

Results

The mortality rate was 0% and there was a 7% risk of sustaining a severe deficit following rebleeding after GKS. None of the patients sustained rebleeding after complete obliteration. Patients with Spetzler-Martin Grade III or less had increased chances of hemorrhage after GKS (p < 0.002). The presence of deep venous drainage, aneurysm, venous hypertension, or periventricular location on angiography was common in patients with hemorrhage after GKS.

Conclusions

The risk of hemorrhage that remains following GKS for cerebral AVMs is highest in the 1st year after treatment. The present study showed a relatively good outcome even in cases with hemorrhage following GKS, with no deaths and minimal morbidity, further substantiating the safety and efficacy of the procedure.
Endovascular treatment of 306 anterior communicating artery aneurysms: overall, perioperative results
Authors: Guglielmi Guido , Viñuela Fernando , Duckwiler Gary , Jahan Reza , Cotroneo Enrico , Gigli Renato
Published: January 2009

Object

A series of 306 consecutive patients with an anterior communicating artery (ACoA) aneurysm is presented. The goal in this study was to report the results of endovascular treatment of ACoA aneurysms in these patients.

Methods

The aneurysms were managed with an endovascular approach in which detachable coils were used. A brief anatomical description of the ACoA and its branches as well as a review of the surgical and endovascular literature is presented. The “ACoA Syndrome” (that is, amnesia and personality changes), which may occur after subarachnoid hemorrhage, is briefly reviewed and described. Recent technical developments that can lead to improved results are also discussed.

Results

Of the 306 aneurysms, 268 (87.5%) were small, 30 (10%) were large, and 8 (2.6%) were giant. One hundred ninety-three aneurysms (63%) had a small neck, whereas 113 (37%) had a wide neck. Sixty-five lesions (21%) were incidental, 5 (2%) presented with symptoms of mass effect, and 236 (77%) presented with a subarachnoid hemorrhage. A complete aneurysm occlusion was attained in 139 cases (45.5%), a neck remnant was detected in 145 (47.5%), and in 22 cases (7%) a residual filling of the aneurysm was observed. Regarding the clinical neurological outcome, 280 patients (91.5%) remained neurologically intact, improved, or unchanged from their initial clinical status. Two large, wide-necked, subtotally occluded aneurysms ruptured 3–7 months after the procedure, with subsequent death of the patients. The procedure-related morbidity and mortality rates were 3.5% (11 cases) and 1% (3 cases), respectively.

Conclusions

The inherently lower risk of injuring or occluding the delicate branches and perforating vessels arising from the ACoA makes the endovascular approach attractive, interesting, and elegant.
Simvastatin for the prevention of symptomatic cerebral vasospasm following aneurysmal subarachnoid hemorrhage: a single-institution prospective cohort study
Authors: McGirt Matthew J. , Garces Ambrossi Giannina L. , Huang Judy , Tamargo Rafael J.
Published: January 2009

Object

Vasospasm is the major cause of disability and death after aneurysmal subarachnoid hemorrhage (aSAH). Although the results of 2 randomized clinical trials demonstrated that statin decreases the incidence of symptomatic cerebral vasospasm after aSAH, retrospective studies have failed to confirm this. The authors conducted a prospective observational study to determine whether a standardized regimen of simvastatin would reduce the incidence of cerebral vasospasm and improve neurological outcomes in patients with aSAH.

Methods

Since 1991, all patients with aSAH admitted to the authors' institution have been prospectively followed up with standardized outcomes recording. Starting in September 2005, all patients admitted with aSAH were given enteral simvastatin (80 mg/day for 14 days) in addition to the standard care. The incidence of symptomatic cerebral vasospasm, length of hospitalization, in-hospital mortality rate, and discharge Glasgow Outcome Scale scores in these 170 patients were compared to data obtained in 170 consecutive patients who underwent treatment in our unit prior to the introduction of statin therapy.

Results

The 5-year study period included 340 consecutively treated patients (170 who received statins and 170 who did not). Patients who received simvastatin therapy were more frequently male (29 vs 20%) and had a smaller median aneurysm diameter (6 vs 7 mm). Baseline characteristics were otherwise similar between the cohorts. There were no differences in the incidence of symptomatic vasospasm (25.3 vs 30.5%; p = 0.277), in-hospital mortality rate (18 vs 15%; p = 0.468), length of hospitalization (21 ± 15 vs 19 ± 12 days; p = 0.281), or poor outcome at discharge (Glasgow Outcome Scale Scores 1–2: 21.7 vs 18.2%; p = 0.416) between the simvastatin and nonstatin cohorts. There were no statin-related complications.

Conclusions

The uniform introduction of simvastatin did not reduce the incidence of symptomatic cerebral vasospasm, death, or poor outcome in patients with aSAH. Simvastatin was well tolerated, but its benefit may be less than has been previously reported.
Collagen matrix duraplasty for posterior fossa surgery: evaluation of surgical technique in 52 adult patients
Authors: Narotam Pradeep K. , Qiao Fan , Nathoo Narendra
Published: January 2009

Object

Complete dural closure is not always possible following posterior fossa surgery, often requiring a graft to secure complete closure. The authors report their experience of using a collagen matrix as an onlay dural graft for repair of a posterior fossa dural defect.

Methods

A retrospective analysis was performed in 52 adult patients who had undergone collagen matrix duraplasty for the posterior fossa. Complications directly related to the dural graft, the presence or absence of hydrocephalus, and the role of closed suction wound drainage in relation to postsurgical pseudomeningoceles were analyzed.

Results

The indication for posterior fossa surgery was tumors in 32 patients, vascular abnormalities in 9 patients, and spontaneous cerebellar hemorrhage in 11 patients. Closed suction wound drainage was used in 23 patients (44.2%). Forty-eight (92.3%) of 52 patients had a dural defect > 2 cm. Nine (81.8%) of 11 patients with hydrocephalus required ventriculoperitoneal shunts. Complications of the surgery included pseudomeningoceles in 2 patients (3.8%; no closed suction wound drainage); superficial wound infections in 1 patient (1.9%; with closed suction wound drainage); and unexplained eosinophilia in 1 patient.

Conclusions

Duraplasty using a collagen matrix is safe and effective in the posterior fossa, and is easy to use and time efficient. Meticulous layered wound closure, the detection and effective control of hydrocephalus, and the use of closed suction wound drainage reduces complications related to collagen matrix duraplasty for the posterior fossa.
Cost-effectiveness analysis of endovascular versus neurosurgical treatment for ruptured intracranial aneurysms in the United States
Authors: Maud Alberto , Lakshminarayan Kamakshi , Suri M. Fareed K. , Vazquez Gabriela , Lanzino Giuseppe , Qureshi Adnan I.
Published: January 2009

Object

The results of the International Subarachnoid Aneurysm Trial (ISAT) demonstrated lower rates of death and disability with endovascular treatment (coiling) than with open surgery (clipping) to secure the ruptured intracranial aneurysm. However, cost-effectiveness may not be favorable because of the greater need for follow-up cerebral angiograms and additional follow-up treatment with endovascular methods. In this study, the authors' goal was to compare the cost-effectiveness of endovascular and neurosurgical treatments in patients with ruptured intracranial aneurysms who were eligible to undergo either type of treatment.

Methods

Clinical data (age, sex, frequency of retreatment, and rebleeding) and quality of life values were obtained from the ISAT. Total cost included those associated with disability, hospitalization, retreatment, and rebleeding. Cost estimates were derived from the Premier Perspective Comparative Database, data from long-term care in stroke patients, and relevant literature. Incremental cost-effectiveness ratios (ICERs) were estimated during a 1-year period. Parametric bootstrapping was used to determine the uncertainty of the estimates.

Results

The median estimated costs of endovascular and neurosurgical treatments (in US dollars) were $45,493 (95th percentile range $44,693–$46,365) and $41,769 (95th percentile range $41,094–$42,518), respectively. The overall quality-adjusted life years (QALY) in the endovascular group was 0.69, and for the neurosurgical group it was 0.64. The cost per QALY in the endovascular group was $65,424 (95th percentile range $64,178–$66,772), and in the neurosurgical group it was $64,824 (95th percentile range $63,679–$66,086). The median estimated ICER at 1 year for endovascular treatment versus neurosurgical treatment was $72,872 (95th percentile range $50,344–$98,335) per QALY gained. Given that most postprocedure angiograms and additional treatments occurred in the 1st year and the 1-year disability status is unlikely to change in the future, ICER for endovascular treatment will progressively decrease over time.

Conclusions

Using outcome and economic data obtained in the US at 1 year after the procedure, endovascular treatment is more costly but is associated with better outcomes than the neurosurgical alternative among patients with ruptured intracranial aneurysms who are eligible to undergo either procedure. With accrual of additional years with a better outcome status, the ICER for endovascular coiling would be expected to progressively decrease and eventually reverse.
The predictive value of low–field strength magnetic resonance imaging for intraoperative residual tumor detection
Authors: Hirschl Robert A. , Wilson Jeff , Miller Brandon , Bergese Sergio , Chiocca E. Antonio
Published: January 2009

Object

Neurosurgeons have been utilizing intraoperative MR (iMR) imaging to evaluate the extent of tumor resection since the 1990s. A low–field strength (0.12 T) MR imaging unit (PoleStar N20, Medtronic) is a practical and relatively inexpensive iMR imaging system that has found increased use in neurosurgery. The gold standard for postoperative detection of residual tumor has been high-strength MR imaging performed within 48 hours of resection. The object of this study was to determine the predictive concordance of low-strength iMR imaging with standard high-strength MR imaging for detection of residual tumor.

Methods

The authors retrospectively evaluated the MR images from 74 intracranial tumor resections, comparing the intraoperative images obtained using a 0.12-T iMR imaging unit to the immediate postoperative images obtained using a standard 1.5-T MR imaging unit within 48 hours after surgery.

Results

The sensitivity of low-field MR imaging for detection of residual tumor was 0.74 (95% CI 0.58–0.86), and its specificity was 0.97 (95% CI 0.83–1). When only glial tumors (42 of the 74 lesions) were analyzed, the sensitivity was 0.82 (95% CI 0.59–0.94) and the specificity was 0.95 (95% CI 0.73–1).

Conclusions

These data could assist the neurosurgeon who has to decide intraoperatively whether the observed iMR images show residual tumor or not.
Intraneural ganglia: a clinical problem deserving a mechanistic explanation and model
Authors: Elangovan Shreehari , Odegard Gregory M. , Morrow Duane A. , Wang Huan , Hébert-Blouin Marie-Noëlle , Spinner Robert J.
Published: January 2009

Intraneural ganglion cysts have been considered a curiosity for 2 centuries. Based on a unifying articular (synovial) theory, recent evidence has provided a logical explanation for their formation and propagation. The fundamental principle is that of a joint origin and a capsular defect through which synovial fluid escapes following the articular branch, typically into the parent nerve. A stereotypical, reproducible appearance has been characterized that suggests a shared pathogenesis. In the present report the authors will provide a mechanistic explanation that can then be mathematically tested using a preliminary model created by finite element analysis.
Distal nerve transfers: a biology-based rationale
Authors: Brown Justin M. , Shah Manish N. , Mackinnon Susan E.
Published: January 2009

Peripheral nerve injuries can result in devastating numbness and paralysis. Surgical repair strategies have historically focused on restoring the original anatomy with interposition grafts. Distal nerve transfers are becoming a more common strategy in the repair of nerve deficits as these interventions can restore function in months as opposed to more than a year with nerve grafts. The changes that take place over time in the cell body, distal nerve, and target organ after axotomy can compromise the results of traditional graft placement and may at times be better addressed with the use of distal nerve transfers. A carefully devised nerve transfer offers restoration of function with minimal (if any) detectable deficits at the donor site. A new understanding of cortical plasticity along with patient reeducation allow for good return of strength and function after nerve transfer.
Spinal cord bypass surgery using peripheral nerve transfers: review of translational studies and a case report on its use following complete spinal cord injury in a human
Authors: Oppenheim Jeffrey S. , Spitzer Daniel E. , Winfree Christopher J.
Published: January 2009

Spinal cord injury has been studied in a variety of in vitro and in vivo animal models. One promising therapeutic approach involves the transfer of peripheral nerves originating above the level of injury into the spinal cord below the level of injury. A model of spinal cord injury in rodents has shown the growth of peripheral nerve fibers into the spinal cord, with the subsequent development of functional synaptic connections and limb movement. The authors of this paper are currently developing a similar model in felines to assess the cortical control of these novel repair pathways. In an effort to determine whether these neurotization techniques could translate to spinal cord injury in humans, the authors treated a patient by using intercostal nerve transfer following complete acute spinal cord injury. The case presented details a patient with paraplegia who regained partial motor and sensory activity following the transfer of intercostal nerves, originating above the level of the spinal cord injury, into the spinal canal below the level of injury. The patient recovered some of his motor and sensory function. Notably, his recovered hip flexion showed respiratory variation. This finding raises the possibility that intercostal nerve transfers may augment neurological recovery after complete spinal cord injury.
Quality gap of educational services at Zahedan University of Medical Sciences, Iran
Authors: Kebriaei Ali , Akbari Fayzollah
Published: January 2009

This study aims to compare quality gap of educational services at Zahedan University of Medical Sciences from students and faculties viewpoints. In a cross-sectional study, survey questionnaire was completed by two distinct groups of respondentsâ 230 faculty members and 384 students. Mass majority of the both groups declared there was negative gap in each of the five dimensions. Mean quality gaps from viewpoint of both groups were negative. The largest mean quality gap from students and faculty members viewpoint was in the responsiveness and tangibility dimensions respectively. The largest and smallest differences between students and faculties viewpoint were in the responsiveness and tangibility dimensions. Keywords: Education; Iran; Medical science; QualityOnline: 29-1-2009DOI: 10.3329/bmrcb.v34i3.1646Bangladesh Med Res Counc Bull 2008; 34: 76-80
Malaria in southeast Bangladesh: A descriptive study
Authors: Maude Richard J. , Dondorp A.M. , Faiz M.A. , Yunus Emran Bin , Samad R. , Hossain Amir , Rahman M. Ridwanur
Published: January 2009

Malaria in Asia is thought to be grossly under-reported and this is evident from previously published statistics from Bangladesh. Malaria screening data from four Upazillas was analysed alongside census data to assess the trends in malaria incidence over time and distribution of malaria by age and gender. Malaria incidence in this area has decreased by around two thirds since 2003, although control measures were not significantly increased until 2005.Â  Malaria occurred in people of all ages with the highest incidence being in young adults. This is consistent with higher occupational exposure in this group. The probability of being screened for malaria decreased with age suggesting significant numbers of adults with malaria may be being missed.Keywords: Bangladesh; MalariaOnline: 29-1-2009DOI: 10.3329/bmrcb.v34i3.1757Bangladesh Med Res Counc Bull 2008; 34: 87-89
Efficacy of nebulized ipratropium bromide versus salbutamol in Infants with actute bronchiolities
Authors: Absar S.M. Nurul , Jahan Salma , Khanum Selina
Published: January 2009

Keywords: Bronchiolities; nebulized; infant; ipratropium; salbutamol;Online: 29-1-2009DOI: 10.3329/bmrcb.v34i3.1861Bangladesh Med Res Counc Bull 2008; 34: 112-112
Major post-operative complications of thyroid surgery: Preventable or not?
Authors: Majid M.A. , Siddique Md. Ibrahim
Published: January 2009

Factors responsible for major complications following thyroid surgery in 598 patients were studied. Patients with non toxic multinodular goiter involving both lobes of thyroid constituted the maximum bulk subjected to thyroidectomy. The most frequent procedure was bilateral subtotal thyroidectomy. Reactionary hemorrhage occurred in 6 patients, all following bilateral procedures and among them 5 patients developed tension hematoma with respiratory obstruction despite the presence of a drain. Temporary vocal cord palsy was observed in 7 patients whereas one patient subjected to total thyroidectomy with neck dissection for papillary carcinoma of thyroid developed permanent right vocal cord palsy. Temporary parathyroid insufficiency was seen in 51 patients and one patient developed permanent hypoparathyroidism. Incidence of parathyroid insufficiency was higher in bilateral procedures as compared to unilateral ones. There was no operation related death in this series, but complications like hemorrhage, vocal cord palsy and parathyroid insufficiency following thyroid surgery are still a deep concern. Keywords: Complication; Post-operative; Thyroid surgeryOnline: 29-1-2009DOI: 10.3329/bmrcb.v34i3.1973Â Â Â Â Â Bangladesh Med Res Counc Bull 2008; 34: 99-103.Â
Catalytic synthesis of (E)-α,β-unsaturated esters from aldehydes and 1,1-diethoxyethylene
Authors: Manzano Rubén , Ozores Lidia , Job Andreas , Rodefeld Lars , List Benjamin
Published: January 2009

A practical and high yielding synthesis of α,β-unsaturated esters from aldehydes and 1,1-diethoxyethylene was developed.
Evolution of Neurotoxins: From Research Modalities to Clinical Realities
Authors: Kostrzewa Richard M.
Published: January 2009

In the 1950s, the discovery of anti‐nerve growth factor, an immunotoxin stunting sympathetic neural development, signaled the advent of neurotoxins as research modalities. Other selective neurotoxins were discovered in rapid succession. In the 1960s, 6‐hydroxydopamine and 6‐hydroxydopa were shown to destroy noradrenergic and dopaminergic nerves. Excitotoxins (glutamate, aspartate, and analogs) were discovered in the 1970s. DSP‐4 [N‐(2‐chloroethyl)‐N‐ethyl‐2‐bromobenzylamine] proved to be selective for noradrenergic destruction, while 5,6‐ and 5,7‐dihydroxytryptamines were relatively selective for serotonin neurons. Additional neurotoxins were discovered, but it was MPTP (1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine) that predominated neurotoxicity research in the 1980s. Eventually,Clostridium botulinumneurotoxin (BoNT), discovered as a “poisonous” principle in the late 1800s, resurfaced in purified and standardized forms as a clinically useful drug. Neurotoxins represent chemical tools, useful not only for discerning neuronal mechanisms and animal modeling of neurological disorders, but also for their use in medicine and potential as treatments for medical disorders. This unit reviews the early discovery of neurotoxins, describes categories of neurotoxins, and finally characterizes their usefulness—first as research tools, and eventually as clinical therapeutic agents.Curr. Protoc. Neurosci. 46:1.18.1‐1.18.10. © 2009 by John Wiley & Sons, Inc.
Use of Mouse Models for the Analysis of Human Disease
Authors: Semsarian Christopher
Published: January 2009

The first half of this unit discusses the two main approaches to developing genetically engineered mouse models of human disease (i.e., transgenesis and gene targeting). The experimental steps for each method are discussed. Potential pitfalls, advantages, and limitations are also addressed. The second half of the unit describes two mouse models of hypertrophic cardiomyopathy, which illustrate the value of studying such models of human disease, both in terms of understanding disease pathogenesis as well as potential new therapeutic avenues. Curr. Protoc. Hum. Genet. 60:15.2.1‐15.2.10. © 2009 by John Wiley & Sons, Inc.
Human iPS Cell Derivation/Reprogramming
Authors: Park In‐Hyun , Daley George Q.
Published: January 2009

This unit describes a protocol for deriving induced pluripotent stem (iPS) cells from human fibroblast cells. Human fibroblast cells are infected with retroviral vectors expressing four transcription factors (Oct4, Sox2, Klf4, and Myc) and selected for 3 to 4 weeks under human embryonic stem (hES) cell culture conditions. iPS cell colonies are mechanically isolated using a dissection microscope and handled like hES cells thereafter. Human iPS cells share similarities with hES cells including the expression of pluripotency genes, and differentiation as embryoid bodies in vitro into three germ layers (EB) and in vivo as teratomas. Curr. Protoc. Stem Cell Biol. 8:4A.1.1‐4A.1.8. © 2009 by John Wiley & Sons, Inc.
Visual acuity in the cathemeral strepsirrhine Eulemur macaco flavifrons
Authors: Veilleux Carrie C. , Christopher Kirk E.
Published: January 2009

Studies of visual acuity in primates have shown that diurnal haplorhines have higher acuity (30–75 cycles per degree (c/deg)) than most other mammals. However, relatively little is known about visual acuity in non‐haplorhine primates, and published estimates are only available for four strepsirrhine genera (Microcebus, Otolemur, Galago, and Lemur). We present here the first measurements of visual acuity in a cathemeral strepsirrhine species, the blue‐eyed black lemur (Eulemur macaco flavifrons). Acuity in two subjects, a 3‐year‐old male and a 16‐year‐old female, was assessed behaviorally using a two‐alternative forced choice discrimination task. Visual stimuli consisted of high contrast square wave gratings of seven spatial frequencies. Acuity threshold was determined using a 70% correct response criterion. Results indicate a maximum visual acuity of 5.1 c/deg for the female (1718 trials) and 3.8 c/deg for the male (846 trials). These values for E. macaco are slightly lower than those reported for diurnal Lemur catta, and are generally comparable to those reported for nocturnal Microcebus murinus and Otolemur crassicaudatus. To examine ecological sources of variation in primate visual acuity, we also calculated maximum theoretical acuity for Cheirogaleus medius (2.8 c/deg) and Tarsius syrichta (8.9 c/deg) using published data on retinal ganglion cell density and eye morphology. These data suggest that visual acuity in primates may be influenced by activity pattern, diet, and phylogenetic history. In particular, the relatively high acuity of T. syrichta and Galago senegalensis suggests that visual predation may be an important selective factor favoring high visual acuity in primates. Am. J. Primatol. 71:343–352, 2009. © 2009 Wiley‐Liss, Inc.
The relation between Pearson's correlation coefficient r and Salton's cosine measure
Authors: Egghe Leo , Leydesdorff Loet
Published: January 2009

The relation between Pearson's correlation coefficient and Salton's cosine measure is revealed based on the different possible values of the division of the L1‐norm and the L2‐norm of a vector. These different values yield a sheaf of increasingly straight lines which together form a cloud of points, being the investigated relation. The theoretical results are tested against the author co‐citation relations among 24 informetricians for whom two matrices can be constructed, based on co‐citations: the asymmetric occurrence matrix and the symmetric co‐citation matrix. Both examples completely confirm the theoretical results. The results enable us to specify an algorithm that provides a threshold value for the cosine above which none of the corresponding Pearson correlations would be negative. Using this threshold value can be expected to optimize the visualization of the vector space.
The decline in the concentration of citations, 1900–2007
Authors: Larivière Vincent , Gingras Yves , Archambault Éric
Published: January 2009

This article challenges recent research (Evans, 2008) reporting that the concentration of cited scientific literature increases with the online availability of articles and journals. Using Thomson Reuters' Web of Science, the present article analyses changes in the concentration of citations received (2‐ and 5‐year citation windows) by papers published between 1900 and 2005. Three measures of concentration are used: the percentage of papers that received at least one citation (cited papers); the percentage of papers needed to account for 20%, 50%, and 80% of the citations; and the Herfindahl‐Hirschman index (HHI). These measures are used for four broad disciplines: natural sciences and engineering, medical fields, social sciences, and the humanities. All these measures converge and show that, contrary to what was reported by Evans, the dispersion of citations is actually increasing.
Insights into metabolic mechanisms underlying folate‐responsive neural tube defects: A minireview
Authors: Beaudin Anna E. , Stover Patrick J.
Published: January 2009

Neural tube defects (NTDs), including anencephaly and spina bifida, arise from the failure of neurulation during early embryonic development. Neural tube defects are common birth defects with a heterogenous and multifactorial etiology with interacting genetic and environmental risk factors. Although the mechanisms resulting in failure of neural tube closure are unknown, up to 70% of NTDs can be prevented by maternal folic acid supplementation. However, the metabolic mechanisms underlying the association between folic acid and NTD pathogenesis have not been identified. This review summarizes our current understanding of the mechanisms by which impairments in folate metabolism might ultimately lead to failure of neural tube closure, with an emphasis on untangling the relative contributions of nutritional deficiency and genetic risk factors to NTD pathogenesis. Birth Defects Research (Part A) 2009. © 2009 Wiley‐Liss, Inc.
Review of published studies of kidney, liver, and gastrointestinal birth defects in fetal alcohol spectrum disorders
Authors: Hofer Ryan , Burd Larry
Published: January 2009

OBJECTIVE: Review of published studies of birth defects of the renal, liver, and gastrointestinal organ systems in subjects with fetal alcohol spectrum disorders (FASD). METHOD: We searched PubMed (http://www.pubmed.gov) using the following terms: fetal alcohol syndrome and: gastrointestinal tract, kidney, liver, and congenital abnormalities for all years and English only citations. RESULTS: We located 12 studies of FASD and defects of or functional impairments for the liver, 12 of renal abnormalities, and only two with gastrointestinal defects. We did not identify specific patterns of malformations or functional deficits for any of the three organ systems. The existing literature suggests a series of nonspecific outcomes in FASD. CONCLUSIONS: Fetal alcohol spectrum disorder includes a diagnostic category of alcohol‐related birth defects which is clinically difficult to apply. This study adds to the existing literature on birth defects in FASD which is still very limited. The categorical diagnosis of alcohol‐related birth defects requires additional research to determine if a specific pattern of organ specific abnormalities or functional deficits emerges in subjects with FASD. Birth Defects Research (Part A), 2009. © 2009 Wiley‐Liss, Inc.
Zoonotic Ljungan virus associated with central nervous system malformations in terminated pregnancy
Authors: Niklasson Bo , Samsioe Annika , Papadogiannakis Nikos , Gustafsson Susanne , Klitz William
Published: January 2009

BACKGROUND:

The Ljungan virus (LV) has been shown to cause central nervous system malformations in laboratory mouse models. The LV has also been associated with intrauterine fetal death in humans. We investigated the presence of LV in a series of human hydrocephaly and anencephaly cases from elective abortions.

METHODS:

A series of elective abortions owing to hydrocephaly, anencephaly, and similarly aged trisomy 21 elective abortions as controls were examined for LV by immunohistochemistry and real time RT‐PCR. A second experiment involved newborn mice exposed to LV.

RESULTS:

LV was diagnosed in 9 of 10 cases with hydrocephalus and in 1 of 18 trisomy 21 controls by immunohistochemistry. Five of nine cases with anencephaly had a positive PCR result, whereas none of the 12 trisomy 21 available for PCR testing had a positive result. The 47 newborn mice exposed to LV all developed encephalitis, with eight having hydrocephalus. None of the 52 control animals had encephalitis or hydrocephalus.

CONCLUSION:

The association between LV and both hydrocephaly and anencephaly suggests that LV may be playing an important role in central nervous system malformations in humans. Birth Defects Research (Part A), 2009. © 2009 Wiley‐Liss, Inc.
Modeling fluid flow through irregular scaffolds for perfusion bioreactors
Authors: Maes Frédéric , Van Ransbeeck Peter , Van Oosterwyck Hans , Verdonck Pascal
Published: January 2009

Direct perfusion of 3D tissue engineered constructs is known to enhance osteogenesis, which can be partly attributed to enhanced nutrient and waste transport. In addition flow mediated shear stresses are known to upregulate osteogenic differentiation and mineralization. A quantification of the hydrodynamic environment is therefore crucial to interpret and compare results of in vitro bioreactor experiments. This study aims to deal with the pitfalls of numerical model preparation of highly complex 3D bone scaffold structures and aims to provide more accurate wall shear stress (WSS) estimates. µCT imaging techniques were used to reconstruct the geometry of both a titanium (Ti) and a hydroxyapatite scaffold, starting from 430 images with a resolution of 8 µm. To tackle the tradeoff between model size and mesh resolution we selected two concentric regions of interest (cubes with a volume of 1 and 3.375 mm3, respectively) for both scaffolds. A flow guidance in front of the real inlet surface of the scaffold was designed to mimic realistic inlet conditions. With a flow rate of 0.04 mL/min perfused through a 5 mm diameter scaffold at an inlet velocity of 33.95 µm/s we obtained average WSSs of 1.10 and 1.46 mPa for the 1 mm3 and the 3.375 mm3 model of the hydroxyapatite scaffold compared to 1.40 and 1.95 mPa for the 1 mm3 model and the 3.375 mm3 model of the Ti scaffold, showing the important influence of the scaffold micro‐architecture heterogeneity and the proximity of boundaries. To assess that influence we selected cubic portions, of which the WSS data were analyzed, with the same size and the same location within both 1 and 3.375 mm3 cubic models. Varying the size of the inner portions simultaneously in both model selections gives a quantification of the sensitivity to boundary neighborhood. This methodology allows to get more insight in the complex concept of tissue engineering and will likely help to understand and eventually improve the fluid‐mechanical aspects. Biotechnol. Bioeng. 2009;103: 621–630. © 2009 Wiley Periodicals, Inc.
Production of recombinant HIV‐1 nef protein using different expression host systems: A techno‐economical comparison
Authors: Vermasvuori Raisa , Koskinen Jani , Salonen Katri , Sirén Noora , Weegar Jan , Dahlbacka John , Kalkkinen Nisse , von Weymarn Niklas
Published: January 2009

Three popular expression host systemsEscherichia coli,Pichia pastorisandDrosophilaS2 were analyzed techno‐economically using HIV‐1 Nef protein as the model product. On scale of 100 mg protein, the labor costs corresponded to 52–83% of the manufacturing costs. When analyzing the cost impact of the different phases (strain/cell line construction, bioreactor production, and primary purification), we found that with the microbial host systems the strain construction phase was most significant generating 56% (E. coli) and 72% (P. pastoris) of the manufacturing costs, whereas with theDrosophilaS2 system the cell line construction and bioreactor production phases were equally significant (46 and 47% of the total costs, respectively). With different titers and production goal of 100 mg of Nef protein, the costs ofP. pastorisandDrosophilaS2 systems were about two and four times higher than the respective costs of theE. colisystem. When equal titers and bioreactor working volumes (10 L) were assumed for all three systems, the manufacturing costs of the bioreactor production of theP. pastorisandDrosophilaS2 systems were about two and 2.5 times higher than the respective costs of theE. colisystem. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009
Metabolic pathway analysis of glycerol metabolism in Klebsiella pneumoniae incorporating oxygen regulatory system
Authors: Zhang Qingrui , Xiu Zhilong
Published: January 2009

It is well known that environmental and genetic perturbations have major effects on the metabolic behavior of cells. In this work, a model that utilizes existing knowledge of oxygen and redox sensing/regulatory system to assist elementary flux modes (EFMs) has been developed and was carried out to predict the metabolic potential of Klebsiella pneumoniae for the production of 1,3‐propanediol (1,3‐PD) under anaerobic and aerobic conditions. It was found that the theoretical optimal 1,3‐PD yield could reach to 0.844 mol mol−1 if the pentose phosphate pathway (PPP), and transhydrogenase had a high flux under anaerobic condition. However, PPP had little influence on the theoretical 1,3‐PD yield, and the flux through tricarboxylic acid (TCA) cycle was high under aerobic conditions. In addition, the effect of oxygen level on the 1,3‐PD and biomass was further analyzed. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009
Water activity‐temperature state diagrams of freeze‐dried Lactobacillus acidophilus (La‐5): Influence of physical state on bacterial survival during storage
Authors: Kurtmann Lone , Carlsen Charlotte U. , Skibsted Leif H. , Risbo Jens
Published: January 2009

Water activity‐temperature state diagrams for Lactobacillus acidophilus freeze‐dried in a sucrose or a lactose matrix were established based on determination of stabilized glass transition temperatures by differential scanning calorimetry during equilibration with respect to water activity at fixed temperatures. The bacteria in the lactose matrix had higher stabilized glass transition temperatures for all aw investigated. The survival of Lactobacillus acidophilus determined as colony forming units for up to 10 weeks of storage at 20°C for (i) aw = 0.11 with both freeze‐dried matrices in the glassy state, (ii) aw = 0.23 with the bacteria in the lactose matrix in a glassy state but with the bacteria in sucrose matrix in the nonglassy state, and (iii) aw = 0.43 with both freeze‐dried matrices in a nonglassy state showed that the nature of the sugar was more important for storage stability than the physical state of the matrix with the nonreducing sucrose providing better stability than the reducing lactose. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009
Crystalline Nanorods as Possible Templates for the Synthesis of Amorphous Biosilica during Spicule Formation in Demospongiae
Authors: Mugnaioli Enrico , Natalio Filipe , Schloßmacher Ute , Wang Xiaohong , Müller Werner E. G. , Kolb Ute
Published: January 2009

In tandem: High‐resolution TEM shows that during the initial stages of demosponge spicule formation, a primordial crystalline structure is formed within the axial filament. The recently developed electron diffraction tomography technique (ADT) reveals that the nanorods have a layered structure that matches smectitic phyllosilicates. These intracellular nanorods have been considered as precursors of mature spicules.

magnified image

High‐resolution microscopy shows that, during the initial stages of demosponge spicule formation, a primordial crystalline structure is formed within the axial filament. The recently developed electron diffraction tomography technique reveals that the nanorods have a layered structure that matches smectitic phyllosilicates. These intracellular nanorods have been considered as precursors of mature spicules.
Leaking hepatic artery aneurysm successfully treated with covered stent
Authors: Hashim Abdelazim , Allaqaband Suhail , Bajwa Tanvir
Published: January 2009

Hepatic artery aneurysm (HAA) is rare with reported incidence of 0.02%. It accounts for ∼12–20% of all visceral aneurysms. The reported risk of rupture ranges from 14% to 80% of all HAAs. Traditionally, HAA has been treated surgically or by transcatheter coil embolization. There are few published reports of percutaneous HAA stenting. We report a case of a 72‐year‐old female with leaking HAA who was successfully treated with endovascular stenting. The authors include a review of the relevant literature. © 2009 Wiley‐Liss, Inc.
Percutaneous versus surgical revascularization for multivessel coronary artery disease: A single center 10 year follow‐up of SOS trial patients
Authors: Buszman Pawel , Wiernek Szymon , Szymanski Radoslaw , Bialkowska Bozena , Buszman Piotr , Fil Wojciech , Stables Rodney , Bochenek Andrzej , Martin Jack , Tendera Michal
Published: January 2009

Objectives: To compare 10 year outcomes including death, left ventricular ejection fraction (LVEF), major adverse cardiovascular and cerebrovascular events (MACCE), repeat revascularization (RR), and severity of angina (CCS) after randomization to stent supported percutaneous coronary intervention (PCI) or surgical revascularization (CABG) in a single center participating in the SOS trial. Background: Randomized studies show increased RR following PCI, but otherwise similar results to CABG in selected mutlivessel disease patients with up to 5 year follow up. There is no 10 year data available. Materials and methods: The analysis involved 100 patients randomized into the SOS study in Poland. Results: Patients were well matched for baseline demographic and angiographic characteristics. During 9.6 ± 0.85 year observation, there was no significant difference between groups for survival, CCS, and LVEF. Increased RR occurred following PCI; 21 (42%) vs. 9 (18%), P < 0.05. As a consequence, the MACCE was also significantly higher following PCI; 36 (72%) vs. 28 (56%), P < 0.05. Excess RR predominantly occurred in the first year and diminished over time with numerically less RR following PCI from year 5 to 10; 2 (4%) vs. 7 (14%), P = ns. Conclusions: These findings suggest that patients with multivessel coronary artery disease technically suitable for either stent supported PCI or CABG have very similar 10 year outcomes with respect to mortality, angina class, LVEF, and MACCE other than RR. Excess RR following PCI predominantly occurs in early years and is numerically lower following PCI in years 5–10. This underscores the need for longer‐term follow up from randomized trials. © 2009 Wiley‐Liss, Inc.