Asif Khan

We report two procedures using a stent-assisted microsurgical clip placement to treat complex intracranial aneurysms originating from supraclinoid segment of the internal carotid artery. In both procedures, primary clip placement was considered technically difficult due to either complex morphology or inferior protrusion of aneurysm fundus within the interclinoid space. A nitinol self-expanding stent was placed across the neck of the aneurysm either preoperatively or intraoperatively. Obliteration of aneurysm and patency of the artery was confirmed by angiography after clip placement. Description of an integrated open microsurgical and endovascular approach and review of literature pertaining to considerations for treatment approach are discussed.

Lumbar catheter placement under fluoroscopic guidance may reduce the rate of technical failures and associated complications seen with insertion guided by manually palpable landmarks. We reviewed our experience with 43 attempted lumbar catheter placements using paramedian approach under fluoroscopic guidance and ascertained rates of technical success, and clinical events. Among the 43 patients, 18, 1, and 1 patients were on aspirin (with dipyrimadole in 2), clopidogrel, and combination of both, respectively. Lumbar catheter placement was successful in 42 of 43 attempted placements. Floroscopic guidance was critical in three patients; one patient had severe cerebrospinal fluid (CSF) depletion (empty thecal sac phenomenon) following pituitary surgery leading to no cerebrospinal fluid return despite correct placement confirmation under fluoroscopy. Two patients had spinal needle placement at the junction between epidural and cerebrospinal fluid spaces (junctional position) leading to c...

Several studies have found supplemental venous drainage channels in addition to bilateral internal jugular veins for cerebral venous efflux. We performed this study to characterize the supplemental venous outflow patterns in a consecutive series of patients undergoing detailed cerebral angiography with venous phase imaging. The venographic phase of the arteriogram was reviewed to identify and classify supplemental cerebral venous drainage into anterior (cavernous venous sinus draining into pterygoid plexus and retromandibular vein) and posterior drainage pattern. The posterior drainage pattern was further divided into plexiform pattern (with sigmoid venous sinus draining into the paravertebral venous plexus), and solitary vein pattern (dominant single draining deep cervical vein) drainage. The posterior plexiform pattern was further divided into 2 groups: posterior plexiform with or without prominent solitary vein. Supplemental venous drainage was seen ipsilateral to internal jugula...

In order to study the genetic basis of fibre characters of Gossypium hirsutum L. lint four varieties namely, MNH-554, Delcerro, Coker-304 and Albacala (71)1190 were crossed in all possible combinations. The genetic analysis of the F1 data showed that effects of general combining ability were significant for fibre length, fibre fineness, fibre strength, fibre whiteness and fibre yellowness as affected by specific combining ability, and these effects were also significant. The greater magnitude of variance resulting from general combining ability suggested that all the fibre characters ere influenced by the genes acting additively except for yellowness which appeared to be influenced by non-additive loci. The varieties differed for their general combining ability for different characters. MNH-554 proved to be the best general combiner for fibre length and fibre whiteness, Coker-304 as better for fibre strength and fibre yellowness, than others and Albacala (71)1190 exhibited its poten...

To assess the diagnostic value of parenchymal hyperdense lesions visualized on the flat-panel CT scan in detecting/excluding intraparenchymal hemorrhage (IPH) after the endovascular treatment of acute stroke patients. Two separate cohorts of acute ischemic stroke patients who underwent endovascular treatment were evaluated. In the first group, patients were evaluated for hyperdense parenchymal lesions immediately after the treatment with flat-panel CT scan; whereas, in the second group, patients underwent multidetector CT scan post procedure. IPH was defined as hyperdensity that persisted for >24 hours on follow up CT scan. A total of 30 patients were evaluated with flat panel, and 135 with multidetector CT scan immediately after the endovascular treatment. Hyperdense lesions were visualized on 7/30 (23%) of those evaluated with flat-panel CT versus 74/135 (55%) of those evaluated with multidetector CT scan. Based on 24-hour follow up imaging, hyperdense parenchymal lesions on im...

The association of venous angiomas or developmental venous anomalies (DVA) with transient neurological deficit is rare. We present a rare case of a cerebellar developmental venous anomaly resulting in transient neurological deficits. A 58-year-old man with recurrent left sided facial dysesthesia, hemiparesis, and mild difficulty ambulating after exercise. A similar episode was experienced six months earlier under the same circumstances. Computed tomographic (CT) scan demonstrated an ill-defined hyperdensity in the right cerebellar hemisphere. Cerebral angiography demonstrated a venous angioma that dilated with valsalva maneuver. We report the first case of a cerebellar venous angioma causing exercise induced transient neurologically deficits. Limiting strenuous exercise may be needed to avoid symptom recurrence. Further research is warranted on the hemodynamic effects of intracranial DVA's.

In June 2012, Food and Drug Administration (FDA) issued a warning about the risk of catheter entrapment associated with Onyx embolization. We used our experience, literature review, and FDA Manufacturer and User Facility Device Experience (MAUDE) data review to identify five strategies to address catheter entrapment: 1/. Surgical resection of vessel at point of entrapment of catheter and retraction from exterior portion at the femoral region; 2/. Advancing and closing the loop of snare over the entrapped catheter followed by retraction; 3/. Advancing the distal access catheter over the entrapped catheter and retraction with forward movement of the distal access catheters; 4/. Inflation of balloon catheter coaxial to the entrapped catheter with subsequent retraction; and 5/. Intravascular retention and internalization of microcatheter. In the MAUDE data, there were 77 reports of catheter entrapment with Onyx embolization; microcatheter was retracted by surgical excision in 15, endova...

Approaching the cervical and high thoracic level epidural space through transepidural route from lumbar region represents a method to lower the occurrence of complications associated with direct approach. The authors performed a cadaveric pilot project to determine the feasibility of various catheter-based manipulation and cephalad advancement using the transepidural route. Two cadavers were used to determine the following: 1. Ability to place a guide sheath over a guidewire using a percutaneous approach within the posterior lumbar epidural space; 2. The highest vertebral level catheter can be advanced within the posterior epidural space; 3. Ability to cross midline within the posterior epidural space; and 4. Ability to catheterize the perineural epidural sheaths of the nerve roots exiting at cervical and thoracic vertebral levels. We were able to advance the catheters up to the level of cervical vertebral level of C2 within the posterior epidural space under fluoroscopic guidance f...

ABSTRACT Unpassivated SiO2/AlInN/AlN/GaN metal─oxide─semiconductor high electron mobility transistors (MOSHEMTs) exhibiting a thin barrier layer are investigated with a particular focus on their dc characteristics dependence on the gate length. The epiwafer exhibits a sheet resistance of ∼250 Ω/□ and a channel charge density of 7.4 × 1012 cm−2 deduced from the 1 MHz capacitance─voltage curves. The results indicate that the thickness of the AlInN barrier can be reduced below 5 nm without degradation of the insulated gate devices performance. For transistors with gate lengths (LG) between 1.8 and 2.0 µm, dc drain saturation currents densities as high as 1.8 A mm−1 are achieved at +4 V gate─source bias (VGS) with very low reverse gate leakage currents. The electron zero-bias drift mobility was determined to be 1670 cm2 V−1 s−1 from the low-field channel conductance measurements. On the other side, using an analytical model it is found that the maximum output current density at VGS = 0 V can be enhanced by ∼23% when LG is scaled from 1.8 µm down to 100 nm. With further improvement of the quality of the gate insulating oxide layer and the implementation of surface passivation, both with the aim of suppressing the observed current collapse, the presented results suggest that these MOSHEMTs could become very attractive for the realization of high-power electronics.

High-grade stenosis of the internal carotid artery (ICA) may result in flow diversion to the external carotid artery (ECA) and its branches. Head and facial pain secondary to flow-diversion to ECA and increase in regional blood flow are under-recognized and unreported. We report a patient with high-grade ICA stenosis and recurrent ipsilateral headaches that resolved after revascularization. A 69-year-old woman presenting with right-arm weakness had neuroimaging evidence of ipsilateral high-grade ICA stenosis and left hemispheric ischemic stroke. Her history was significant for unilateral recurrent headaches that clinically resolved after left ICA angioplasty and stenting. With prior evidence supporting extracranial vasodilatation as the source of pain in migraine, and current clinical observation, we propose flow-diversion phenomenon as the connection between high-grade ICA stenosis and ipsilateral headache. Recognition of flow-diversion into the ECA as a possible mechanism for head...

Cerebrovascular ischemic events associated with giant cell arteritis (GCA) are uncommon and have been reported in 3%-4% of patients. We describe a case report of GCA associated with intracranial stenosis and review various angiographic findings. A 66-year-old man presented with worsening headache and vision loss. A recent magnetic resonance angiogram of the head and neck showed multiple intracranial stenosis. Cerebrospinal fluid (CSF) analysis demonstrated increased protein of 135.6 mg/dL, with two white blood cells/µL. No bacteria were observed in the CSF on gram staining, and cultures were negative for bacterial growth. Erythrocyte sedimentation rate was noted to be 14 mm/h, and C-reactive protein was 1.514 mg/L at admission. Human immunodeficiency virus (HIV) and hepatitis panels were negative. On digital subtraction angiography, patient had predominantly narrowing and irregularities in petrous and cavernous segments of the internal carotid arteries bilaterally. The diagnosis of ...

Running Title: Sympathetic Block for Ventricular Tachycardia Storm. We present the case of a patient with ventricular tachycardia storm refractory to medical therapy and multiple catheter ablations, successfully managed by percutaneous left inferior cervical sympathetic ganglion block. A 70-year-old man with a history of ischemic cardiomyopathy and previous placement of implantable defibrillator developed intractable ventricular tachycardia recalcitrant to intravenous amiodarone, lidocaine, and multiple catheter ablations with radiofrequency energy and direct current. The patient received numerous defibrillator shocks that did not result in sustained restoration of sinus rhythm. A percutaneous inferior cervical sympathetic ganglion block was performed under fluoroscopic guidance, with the administration of bupivacaine by infiltration of the tissue between the left internal carotid artery and the cervical vertebral bodies. Two and a half hours after the procedure, ventricular tachyca...

Liquid embolization using Onyx® of brain arteriovenous malformations (AVMs) is sometimes limited by micro catheter retention by Onyx® cast during the disengagement process. Use of the new detachable tip micro catheter is presented in this report. Two feeding arteries of a previously ruptured brain AVM in a 62-year-old man were embolized by Onyx 18 prior to surgery using the new Apollo™ micro catheter with the detachable-tip (30 mm) was utilized. The arterial feeders were accessed without difficulty by micro catheter, guided by 0.010" microwire. Onyx reflux around the distal end of the micro catheter was necessary for effective embolization of arteriovenous fistulous components of brain AVM. The micro catheter was successfully retracted after embolization in both feeding arteries, with distal end detachment seen in one but not the other arterial embolization. No arterial thrombosis, vasospasm, dissection, or rupture was seen at respective sites of disengagement. Use of the new m...

The present report describes the effect of intra-arterial injection of a dose of 40 mg lidocaine and 20 mg methylprednisolone into the middle meningeal artery of two patients suffering from severe headaches. The effect of injection of lidocaine and methylprednisolone was short lasting with effect manifesting within 5 min and lasting 5-8 h after injection. Both patients reported improvement in headache intensity after 24 h post-procedure. Intra-arterial injection of lidocaine and methylprednisolone may represent another treatment strategy for headaches not responsive to standard treatment.

Plant production is severely affected by diseases. On other hand, R-genes exhibited resistance against range of diseases and pathogens in plants. The nucleotide binding site and leucine rich repeat (NBS-LRR) class of R-genes is the most comprehensively studied in terms of sequence evolution and genome distribution and makes it a super-family of R genes. The differential response for resistance against biotic and abiotic stress has been observed in cultivated and wild relatives of genus Gossypium. The efforts have been made to address the recent evolution of NBS-LRR sequences within the Gossypium hrisutum and RGAs sequences derived from G. arboreum and G. raimondii. Percent identity and phylogenetic analysis of NBS-LRR encoded RGAs from tetraploid new world cotton and its diploid ancestors, G. raimondii and G. arboreum suggest that the evolution of NBS-LRR encoding sequences in G. hirsutum occurred by gradual accumulation of mutants that led to positive selection and slow rate of div...

A new approach based on the Nernst-Planck equations has been applied to study the reaction kinetics on the surface of tin(IV) tungstate for the Mg(II)-H(I), Ca(II)-H(I), Sr(II)-H(I) and Ba(IT)-H(I) exchanges under the conditions favouring a particle diffusion phenomenon. On the basis of these studies the various physical parameters such as the effective diffusion coefficients, activation energies and entropies of activation

The Carotid Revascularization Endarterectomy versus Stenting Trial (CREST) demonstrated that the risk of the primary composite outcome of stroke, myocardial infarction (MI), or death did not differ significantly in patients with an average surgical risk undergoing carotid artery stenting (CAS) and those undergoing carotid endarterectomy (CEA). However, the cost associated with CAS may limit its broad applicability. The authors' goal in this paper was to determine the cost-effectiveness of CAS with an embolic-protection device versus CEA in patients with moderate to severe carotid artery stenosis who are at average surgical risk. The probability of the primary outcome was obtained from the results of the CREST trial. The quality-adjusted life years (QALYs) associated with each treatment modality were estimated by adjusting for the incidence of each quality-adjusted outcome (QALY weights of ipsilateral stroke, MI, death, and postprocedure QALYs). The total cost associated with each intervention was derived from hospitalization cost and cost associated with primary outcomes including stroke, MI, and death in each group. Costs are expressed in US dollars accounting for inflation up to October 2010. Incremental cost-effectiveness ratios (ICERs) were estimated for the 4-year period after the procedure. All values are expressed as means and 95% confidence intervals. The estimated net costs for patients after treatment with CAS and CEA after consideration of the primary outcome were $18,335 and $13,276, respectively, from the definitive presimulation analysis. Postsimulation values were $19,210 (range $18,264-$20,156) and $14,080 (range $13,076-$15,084), respectively. Overall, QALYs for the CAS and CEA groups were 0.712 and 0.702, respectively (ranging from 0.0 [death] to 0.815 [no adverse events]). The estimated ICER for CAS versus CEA treatment was $229,429. Although the CREST demonstrated equivalent results with CAS (compared with CEA) in patients at average surgical risk with severe carotid artery stenosis, broad applicability of CAS might be limited by the higher cost associated with this procedure.

Sex ratio, size and age at first maturity, maturation and spawning, breeding season, and fecundity of L. gonius were investigated in the river Kali.The overall sex ratio between males and females was 1 : 1·86. Males were dominant in the smaller size groups and the females in larger ones. Males matured earlier than the females, at a length of 170

Abstract The effect of high-temperature annealing of undoped AlGaN/GaN heterostructures on different substrates was systematically studied between 1100° C and 1230° C. An AlN spacer layer was found to add stability to structures on sapphire substrates. AlGaN/GaN ...

We report on the effect of dry etching and the combination of metal stacks used to form ohmic contacts on silicon-doped high-Al-content (>60%) n-AlGaN layers for deep-ultraviolet light-emitting diodes. The contact characteristics are compared for as-grown and plasma-etched n-AlGaN samples. The Ti/Al/Ti/Au contacts to as-grown n-AlGaN were linear, with a specific contact resistivity of 5 × 10−5 Ω-cm2. The same metallic layer

Temperature-dependent photoluminescence (PL) measurements were performed for A-plane and C-plane bulk AlN single crystals and epitaxial layers on sapphire. A strong near-band-edge (NBE) emission and deep-level luminescence were observed. At low excitations, the ...

In this paper, we report a wireless magnetoelastic (ME) biosensor with phage as the bio-recognition probe for real time detection of Salmonella typhimurium. The ME biosensor was constructed by immobilizing filamentous phage that specifically binds with S. typhimurium onto the surface of a strip-shaped ME particle. The ME sensor oscillates with a characteristic resonance frequency when subjected to a time varying magnetic field. Binding between the phage and antigen (bacteria) causes a shift in the sensor's resonance frequency. Sensors ...