Renal artery pseudoaneurysm following robot assisted nephron sparing surgery: two case reports.

BACKGROUND: Renal artery pseudoaneurysm following partial nephrectomy is a rare entity, the incidence of this entity is more common following penetrating abdominal injuries, percutaneous renal interventions such as percutaneous nephrostomy(PCN) or Percutaneous nephrolithotomy (PCNL). Although rare, renal artery pseudoaneurysm can be life threatening if not managed timely, they usually present within two weeks postoperatively with usual presenting complains being gross haematuria, flank pain and/or anaemia. CASE PRESENTATION: We report case of two female patients 34 and 57 year old respectively of South Asian ethnicity, presenting with renal artery pseudoaneurysm following left sided robot assisted nephron sparing surgery for interpolar masses presenting clinically with total, painless, gross haematuria with clots within fifteen days postoperatively and their successful treatment by digital subtraction angiography and coil embolization. CONCLUSION: Renal artery aneurysm is a rare fatal complication of minimally invasive nephron sparing surgery however considering the preoperative and intraoperative risk factors for its development and prompt suspicion at the outset can be life saving with coil embolization of the bleeding arterial aneurysm.

Recurrent Third Nerve Paresis with Migraine: A Case Report and Review of the Literature.

Ophthalmoplegic migraine (OM), first described by Charcot in 1870, is a disorder characterised by recurrent episodes of migraine associated with ophthalmoplegia. It has been extensively described in children and is rarer in adults. Commonly, the third nerve is affected with pupillary involvement and, more rarely, the fourth or the sixth nerve. OM is now believed to be an inflammatory demyelinating neuropathy. However, in the largest series of OM so far, by Lal et al. it most commonly involved the sixth nerve, started with a crescendo migraine and was accompanied by no enhancement of the cranial nerves. This has led to a rethink about the role of migraine, in the pathogenesis of OM. We describe a 14-year-old boy, with a 10-year history of intermittent headache followed by drooping of right eyelid and diplopia. The current episode started with a migrainous headache, which increased in severity over 3 days, followed by right third nerve paresis with pupillary involvement. Contrast-enhanced magnetic resonance imaging (MRI) of the brain with contrast showed nodular thickening at the root entry zone of the right oculomotor nerve with bright enhancement. The child responded to oral prednisolone, which was tapered over a month. Migraine prophylaxis with propranolol was concurrently added. His repeat MRI brain showed complete disappearance of enhancement of the lesion at 1 year.

Phytochemical Screening and Evaluation of Pesticidal Efficacy in the Oleoresins of Globba sessiliflora Sims and In Silico Study.

Globba sessiliflora Sims is an aromatic rhizomatous herb of family Zingiberaceae which is endemic to Peninsular India. This study first reports the phytochemical profile and pesticidal potential of oleoresins obtained from the aerial and rhizome parts of Globba sessiliflora Sims. The oleoresins were prepared by the cold percolation method and were analyzed by a gas chromatography-mass spectrometry (GC-MS) method. Both the oleoresins varied greatly in composition, the major compounds identified in aerial part oleoresin (GSAO) were methyl linoleate, methyl palmitate, and phytol, while the major compounds present in rhizome part oleoresin (GSRO) were γ-sitosterol, 8 (17),12-labdadiene-15, 16-dial, methyl linoleate, and methyl palmitate. In order to evaluate the biological activities, the oleoresins were tested under laboratory conditions for nematicidal action and inhibition of egg hatching potential against root knot nematode, where GSRO was more effective. Insecticidal activity was performed against mustard aphid, Lipaphis erysimi and castor hairy caterpillar, Selepa celtis. In case of mustard aphid, GSRO (LC50 = 154.8 ppm) was more effective than GSAO (LC50 = 263.0 ppm), while GSAO (LC50 = 346.7.0 ppm) was more effective against castor hairy caterpillar than GSRO (LC50 = 398.1 ppm). The herbicidal activity was performed in the receptor species Raphanus raphanistrum subsp. sativus, and the oleoresins showed different intensities for seed germination inhibition and coleoptile and radical length inhibition. Molecular docking studies were conducted to screen the in vitro activities and through molecular docking, it was found that the major oleoresins components were able to interact with the binding pocket of HPPD and AChE with γ-sitosterol showing the best binding affinity.

Painful Convictions: Examining Pain Management Malpractice Claims From Incarcerated Patients, 2000-2020.

We aim to characterize the legal landscape of incarcerated patients' pain management malpractice claims and to discuss the ethical and policy implications that result. The most common rationales for lawsuits were failure to completely treat (38 [46.3%]), failure to offer (34 [41.4%]), and delay of treatment (6 [7.3%]). In cases won by defendants, the most common rationale for verdicts was no deliberate indifference occurred (74 [86.6%]). We found that incarcerated individuals were often unsuccessful in litigating claims for inadequate pain management despite several cases pointing toward treatment strategies far below what would be ethically accepted as standard of care in the community setting.

Trigeminal Nerve Melanotic Schwannoma in Carney Complex.

Melanotic schwannoma (MS) is a rare peripheral nerve sheath tumor commonly found in the thoracic paraspinal region. It is present in an intracranial location rarely, with 18 out of 105 MS cases described in the literature. Trigeminal nerve was involved in only six of these cases. Fifty percent of psammomatous melanotic schwannoma (PMS) patients have Carney complex. Carney complex is an autosomal dominant disorder featuring peripheral nerve tumors (schwannomas), myxomas (heart, skin, and breast), skin pigmentation (lentigines and blue nevi), and endocrine tumors (adrenal, testicular, and pituitary). We present a case of left trigeminal nerve PMS as a part of Carney complex. Patient had diffuse lentiginosis. Magnetic Resonance Imaging revealed enhancing lesion along left trigeminal nerve with widened Meckel's cave and foramen ovale. Final diagnosis of PMS was derived on clinical, radiological, and histopathological findings with immunohistochemistry correlation. Key Message Trigeminal nerve can be rarely involved in melanotic schwannoma (MS). Knowledge of typical radiological features of MS is crucial for its diagnosis. Its association with Carney complex should be sought.

Chemical Composition and Biological Activities of Hedychium coccineum Buch.-Ham. ex Sm. Essential Oils from Kumaun Hills of Uttarakhand.

Hedychium coccineum Buch. Ham. ex Sm. is a perennial rhizomatous herb belonging to the family Zingiberaceae. The aim of the present study was to compare the chemical composition and biological activities of H. coccineum rhizome essential oil (HCCRO) and H. coccineum aerial part essential oil (HCCAO). The plant material was subjected to hydro-distillation using Clevenger's apparatus in order to obtain volatile oil and analyzed for its chemical constituents using GC-MS. The comparative study of the rhizome and aerial part essential oils of H. coccineum displayed that (E)-nerolidol (15.9%), bornyl acetate (13.95%), davanone B (10.9%), spathulenol (8.9%), and 1, 8-cineol (8.5%) contributed majorly to the HCCRO, while 7-hydroxyfarnesen (15.5%), α-farnesene (11.1%), α-pinene (10.9%), spathulenol (7.7%), and ß-pinene (6.8%) were present as major constituents in the HCCAO. Both the essential oils were studied for their biological activities, such as nematicidal, insecticidal, herbicidal, antifungal, and antibacterial activities. The essential oils exhibited significant nematicidal activity against Meloidogyne incognita, insecticidal activity against Spodoptera litura, and moderate herbicidal activity against R. raphanistrum sub sp. sativus, and good antifungal activity against Fusarium oxysporum and Curvularialunata. Essential oils were also tested for antibacterial activity against Staphylococcus aureus and Salmonella enterica serotype Typhi. Both oils showed good to moderate activity against the tested pathogens. The significant nematicidal, insecticidal, herbicidal, antifungal, and antibacterial activities of both the essential oils might be helpful for the development of environmentally friendly pesticides that could be an alternative to synthetic pesticides in the future.

Auditory aura from the hippocampus - Not all that 'rings' is neocortical temporal lobe epilepsy.

Epileptic auras provide the initial clues to identify the probable region of ictal onset. In temporal lobe epilepsies, auras are most commonly experiential or viscerosensory, when they arise from mesial structures. Whereas sensations such as vertigo and auditory hallucinations are more likely to occur from the lateral temporal lobe structures. Auditory auras have been described from the lateral temporal neocortex, Heschl's gyri, frontal operculum and posterior insula. We herein describe a patient with temporal lobe epilepsy with an auditory aura who was localized to have the onset of seizures from the hippocampus using stereotactic EEG (SEEG). Stimulation of the hippocampal contacts also reproduced the habitual auditory aura. Anterior temporal lobectomy with amygdalohippocampectomy resulted in complete seizure freedom for 3 years. This is an initial description of auditory aura elicited from the hippocampus using SEEG.

Coronavirus Disease 2019 (COVID-19)-Associated Rhino-Orbito-Cerebral Mucormycosis: A Multi-Institutional Retrospective Study of Imaging Patterns.

BACKGROUND: Mucormycosis infection of the maxillofacial region and brain has been associated with coronavirus disease 2019 (COVID-19) infection. Mucormycosis was relatively a rare infection before COVID-19, and imaging findings are not very well described. MATERIALS AND METHODS: A retrospective imaging study of 101 patients diagnosed with COVID-19-associated mucormycosis by histopathology and/or culture was performed. All patients underwent computed tomography and/or magnetic resonance imaging based on the clinical condition of the patient and on consensus decision by the team of treating physicians. A simple 3-stage classification system based on imaging findings was adopted. RESULTS: One hundred one cases were included in the final analysis (mean age = 55.1 years; male/female ratio = 67:34). The affected patients had diabetes in 94% of the instances (n = 95), 80.1% (n = 81) received steroids), whereas 59.4% (n = 60) patients received supplemental oxygen. The majority underwent surgical intervention, whereas in 6 cases, patients were treated with antibiotic regimens. Sixty subjects improved following therapy, whereas 18 eventually succumbed to the illness. We noted a significant positive correlation between the imaging stage and outcomes. No association was seen between other clinical parameters and final clinical outcomes. Salient imaging findings include lack of normal sinonasal mucosal enhancement, perisinus inflammation, ischemic optic neuropathy, perineural spread, pachymeningeal enhancement, and presence of strokes. CONCLUSIONS: We describe the imaging findings in the largest cohort of patients with rhino-orbito-cerebral mucormycosis in the context of the current COVID-19 pandemic. A simplified staging system described here is helpful for standardized reporting and carries prognostic information.

Comparative Study of Morphology and Developmental Biology of Two Agriculturally Important Whitefly Species Bemisia tabaci (Asia II 5) and Trialeurodes vaporariorum from North-Western Himalayan Region of India

Abstract: Bemisia tabaci (Asia II 5) and Trialeurodes vaporariorum are the two devastating species of whiteflies infesting a wide range of vegetable crops in the North-Western Himalayan region. Therefore, the present investigation deals with a comparative study of the morphology and developmental biology of these two whitefly species. The total developmental period from egg to adult was 22.82 and 23.40 days for B. tabaci (Asia II 5) and T. vaporariorum, respectively, which did not differ significantly. The adult longevity, fecundity, and adult emergence in T. vaporariorum is quite higher than B. tabaci (Asia II 5) which were observed as 10.40 days, 118.00 eggs/female, 90.69 per cent and 6.80 days, 73.33 eggs/female, 86.59 per cent, respectively. Similarly, the egg hatching and the survival rate is higher in T. vaporariorum than in B. tabaci (Asia II 5) (95.11, 81.44 per cent and 91.68, 78.09 per cent). Morphological characters such as marginal setae, abdominal setae, vasiform orifice, lingula, and antennae, which were reliable characters for the identification of both whitefly species and diagnostics of the two whiteflies, were explicated in a comparative discussion.

Essential oil composition and biological activities determination of Mosla dianthera (Buch.-Ham. ex Roxb.) Maxim. and its major isolated component, carvone

Abstract This study was aimed to explore the chemical composition and biological activities of essential oil from aerial part of Mosla dianthera along with its major isolated compound, carvone. The hydro-distilled essential oil was analysed by GC-MS and biological activities were investigated in terms of antioxidant, anti-inflammatory, herbicidal, antibacterial, anti-fungal and anti-feedant properties. GC-MS analysis led to the identification of forty-nine components contributing 96.2% of essential oil with carvone (41.9%) as the most abundant constituent. The oil and carvone showed good to moderate antioxidant potentials determined by radical scavenging, reducing power and metal chelating activities. Carvone showed good anti-inflammatory activity (78.0%) compared to essential oil (74.2%). Both essential oil and carvone exhibited excellent herbicidal activity against Raphanus raphanistrum subsp. sativus seeds. The essential oil and carvone showed significant anti-bacterial efficacy against Bacillus cereus and Escherichia coli. It was observed that essential oil showed strong antifungal property than carvone against Alternaria alternata and Curvularia lunata. Both the samples exhibited anti-feedant activity in a dose dependent manner against third instar larvae of Spilosoma obliqua. Results obtained revealed the possible applications of essential oil and carvone as a bioactive source of natural antioxidants, excellent herbicide and an effective substance for antifungal and antifeedant activities.

Effect of Transurethral Resection of the Prostate on Urodynamic Parameters in Patients with Benign Prostatic Enlargement with Upper Urinary Tract Dilatation.

OBJECTIVE: To evaluate the urodynamic outcomes of transurethral resection of the prostate (TURP) in patients of benign prostatic enlargement (BPE) with upper urinary tract dilatation and correlate with International Prostate Symptoms Score (I-PSS). METHODS: In this prospective study, patients of BPE with upper urinary tract dilatation from July 2017 to June 2019 were enrolled. At presentation, detailed I-PSS, ultrasonography abdomen, serum creatinine, and serum PSA were recorded. All the patients were catheterized and observed for postobstructive diuresis. At 4 weeks, repeat ultrasound and serum creatinine were recorded. Urodynamic study (UDS) was performed after ensuring sterile urine culture. Patients underwent TURP as per the standard technique. A repeat UDS was performed after 3 months, and analysis was done. RESULTS: Forty-four patients were enrolled of which data of 37 patients were analyzed. In the filling phase of the UDS, there was a significant decrease in detrusor pressure at the end filling phase from 27 to 9.0 cm H2O after TURP. Maximum cystometric capacity and bladder compliance significantly improved at 3 months following surgery. In the voiding phase, peak flow rate showed a significant increase, postvoid residual urine volume significantly decreased, and peak detrusor pressure marginally decreased following TURP. The I-PSS decreased from 20 ± 8 to 5 ± 6 following TURP. CONCLUSION: High detrusor pressure and reduced compliance is a risk factor for upper urinary tract dilatation. Changes in the bladder dynamics and resolution of hydronephrosis following TURP reflected in the changes in urodynamic parameters and I-PSS.

Dorsolateral inner preputial graft urethroplasty for anterior urethral strictures: long-term outcomes from a single tertiary care centre.

PURPOSE: Buccal mucosa graft (BMG) is long used as favoured substitute by most reconstructive surgeons for substitution urethroplasty (SU). Though inner preputial skin graft (IPG) was described even earlier than BMG, its usage lately has fallen out of favour. The aim of the study was to evaluate the outcome of a SU with IPG from a tertiary care centre. METHODS: A retrospective analysis of prospectively maintained clinical data was conducted at our tertiary care centre enrolling 80 patients with anterior urethral stricture from January 2015 to January 2018. Patients were evaluated for the aetiology, length and site of the urethral stricture. All patients underwent dorsolateral SU with IPG. Post-operative assessment including uroflowmetry and sexual outcomes using IIEF and MSHQ-EJD questionnaires was done at 3 weeks, 3 months, 12 months and half-yearly thereafter. Success was defined by the stable maximum urinary flow value > 14 ml/s or urethral calibration with 16 French Foley catheter. RESULTS: Mean age of patients was 40 years (18-69). The most common aetiology was post-instrumentation (65%) and 60% had stricture at penobulbar site. Mean stricture length was 65 mm. At a mean follow-up of 48 months (range 30-66 months), successful outcomes were seen in 69/80 (87%). Patients with failure were managed with optical internal urethrotomy (OIU). Uroflowmetry and obstructive symptoms significantly improved and sexual function remained unaffected using IPG for SU. CONCLUSIONS: Preputial graft is a tissue familiar to the urologist, located very close to the surgical field, easily harvested and operated under regional anaesthesia. Overall success outcomes are acceptable to BMG urethroplasty.

Off-label Studies on the Use of Ruxolitinib in Dermatology.

PURPOSE: Ruxolitinib (Jakafi) is a Janus kinase 1 and 2 small molecule inhibitor that the Food and Drug Administration approved for myelofibrosis and polycythemia vera. It has been expanded to off-label treatment for a variety of dermatologic conditions, with several clinical trials ongoing. A review of available studies and cases of off-label uses was performed to guide clinicians seeking evidence on the efficacy of this Janus kinase inhibitor for dermatologic disorders. MATERIALS AND METHODS: PubMed/MEDLINE, EMBASE, Scopus, and ClinicalTrials.gov databases were searched with the term "ruxolitinib," and results were manually reviewed to identify published data on off-label uses of ruxolitinib. Studies included are structured by quality of evidence available. RESULTS: Ruxolitinib may have utility in the treatment of atopic dermatitis, psoriasis, and vitiligo, with data from open-label and randomized trials supporting efficacy of topical formulations. Evidence of utility for alopecia areata is mixed and differs depending on topical versus oral form. Evidence for numerous other conditions is available through case reports and case series. CONCLUSIONS: There is growing evidence supporting potential off-label use of oral and topical ruxolitinib for a wide range of skin conditions. There are several ongoing investigations of ruxolitinib use in dermatology that will undoubtedly better define its efficacy and appropriate use in dermatology.

Central nervous system high grade neuroepithelial tumor with BCOR immunopositivity: Is there a molecular heterogeneity?

Central nervous system high grade neuroepithelial tumor - BCOR altered is a newly defined entity which is characterised by internal tandem duplication (ITD) in exon 15 of BCOR. These tumors resemble high grade glioma histologically and exhibit BCOR immunopositivity. However, recently fusions of BCOR are also described in CNS lower grade gliomas, thus questioning the sensitivity and specificity of BCOR immunohistochemistry for identification of BCOR-ITD. We describe four cases of high grade neuroepithelial tumor with BCOR immunopositivity which were diagnosed over a period of one year at our institute. Amongst these, only one tumor revealed BCOR-ITD on sequencing. SATB2 immunopositivity which is a sensitive marker of BCOR-ITD, BCOR fusions and YWHAE fusions was noted in three out of four cases. Our study suggests that BCOR immunopositive CNS high grade tumors are molecularly heterogeneous and could harbour genetic alterations other than BCOR-ITD.

Social Media Responses to Elective Surgery Cancellations in the Wake of COVID-19.

OBJECTIVE: To assess public response to cancellations of elective surgeries following the American College of Surgeons' (ACS) recommendation on March 13. METHODS: We queried text comments from Reddit, a social media platform and the fifth most popular website in the United States. Comments were manually reviewed to assess for relevance to elective surgery in the United States during the global coronavirus outbreak, whether the text was written by a healthcare worker (HCW), whether the user was based in the United States, and whether the text documented cancellations of surgery, expected cancellations of surgery, or surgery ongoing after the ACS announcement. Analysis of overall sentiment and negativity in comment text was performed using the Valence Aware Dictionary for sEntiment Reasoning (VADER), a validated natural language processing tool previously used in studies of health behaviors using social media. Non-parametric tests were used for subgroup comparisons based on posting date and characteristics identified during manual review. RESULTS: Following manual review, 1272 comments were included for analysis. Overall sentiment among non-HCWs became significantly more negative following the ACS announcement (P = 0.037). Overall sentiment did not significantly differ between HCWs and non-HCWs prior to the ACS announcement (P = 0.98), but non-HCW sentiment became significantly more negative than HCW sentiment after the announcement (P = 0.027). Negativity scores in posts describing cancellations were significantly higher among posts written by non-HCWs than HCWs (P = 0.028). CONCLUSIONS: Cancellation of elective surgeries had an adverse emotional impact on non-HCWs. This finding highlights the importance of access to elective surgery to patients' emotional well-being.

Neuropraxia: An Underappreciated Morbidity of Liver Transplantation.

BACKGROUND: Peripheral nerve injuries can be devastating complications of surgery, potentially resulting in severe functional disability and decreased quality of life. Long surgeries with considerable tissue manipulation, for example, liver transplantation, may present increased risk; however, neuropraxia in transplantation has not been well investigated. MATERIALS AND METHODS: This is a retrospective study of all adult patients undergoing liver transplantation at a large academic center between January 2013 and December 2015. Descriptive analyses, logistic regressions, and forward selection procedures were used to determine the odds of developing neuropraxia and associated factors. RESULTS: Of the 283 liver recipients, the mean age was 55.8 y, 35.1% were female, 65.6% were Caucasian, 8.9% were African American, 16.7% were Hispanic, and mean model for end-stage liver disease sodium score at transplant was 24.2 ± 10.9. The underlying etiology was alcohol (26.2%), hepatitis C (34.8%), nonalcoholic steatohepatitis (13.1%), and other (14.2%). The incidence of neuropraxia after liver transplantation was 8.3% (n = 25), with 60% (n = 16) upper extremities, 82% left sided, and 84% male. There was no difference in age, race, body mass index, hypertension, diabetes, hyperlipidemia, or smoking in those with neuropraxia versus those without. In multivariate analysis, neuropraxia was significantly associated with male gender, lower model for end-stage liver disease score, and longer duration of surgery (P < 0.05). Symptoms lasted median 5 d, with a wide range up to 187 d. Neuropraxia-specific treatment (physical therapy or medications) was required in 32% (n = 9). CONCLUSIONS: Peripheral nerve injuries are an unexplored complication of liver transplantation. Although transient, a high number (8.2%) of patients developed neuropraxia, negatively affecting their ability for recovery. Exploration of mechanisms for minimizing risk and intraoperative detection and prevention should be considered to mitigate this complication.

Ternary complex formation of AFN-1252 with Acinetobacter baumannii FabI and NADH: Crystallographic and biochemical studies.

Acinetobacter baumannii is an opportunistic Gram-negative bacterial pathogen, associated mostly with hospital-acquired infections. The emergence of drug resistance strains made it necessary to explore new pathways for the development of more effective antibiotics. Enoyl CoA reductase (FabI), a key enzyme in the fatty acid biosynthesis (FAS) pathway, has emerged as a potential target for antibacterial drug development. Earlier reports show that the lead SaFabI inhibitor AFN-1252 can inhibit FabI from other organisms including Escherichia coli and Burkholderia pseudomallei, but with differential potency. In the present work, we show that AFN-1252 is a moderate inhibitor of AbFabI with an IC50 of 216 nM. AFN-1252 stabilized AbFabI with a 4.2°C increase in the melting temperature (Tm ) and, interestingly, the stabilization effect was significantly increased in presence of the cofactor NADH (∆Tm  = 17°C), suggesting the formation of a ternary complex AbFabI: AFN-1252: NADH. X-ray crystallography studies of AbFabI co-crystalized with AFN-1252 and NADH confirmed the ternary complex formation. The critical interactions of AFN-1252 with AbFabI and NADH identified from the co-crystal structure may facilitate the design and development of new drugs against A. baumannii infections by targeting the FAS pathway.

Anterior Transpetrosal Approach for Petroclival Meningioma: Operative Nuances.

Petroclival meningiomas are unique neurosurgical challenges that require planning an approach to the retrosellar and upper and mid retroclival locations. The classical subtemporal-transtentorial approach went into disrepute due to excessive brain retraction. To resolve this challenge Buchenek and Kukwa introduced extradural approach with drilling of the petrous bone and called it the extended middle fossa approach. It was Kawase et al who modified the extended middle fossa approach initially for dealing with basilar trunk aneurysms. This anterior transpetrosal approach has been described below for dealing with the petroclival meningiomas.

Trapped ipsilateral lateral ventricle: a delayed complication of hemispherotomy for Rasmussen's encephalitis.

Hemispherotomy is the currently preferred surgical treatment option for refractory unihemispheric epilepsies. The incidence of hydrocephalus is greatly reduced in this disconnective procedure when compared with the resective procedure of anatomical hemispherectomy. We describe the occurrence of ipsilateral trapped lateral ventricle months after hemispherotomy for Rasmussen's encephalitis. There is enough evidence to suggest that this rare and interesting complication is due to the local inflammatory changes associated with the surgical trauma.

Response of Gallium Nitride Chemiresistors to Carbon Monoxide is Due to Oxygen Contamination.

We report on the influence of oxygen impurities on the gas sensing properties of gallium nitride (GaN) chemiresistors. As shown by XRD, elemental analysis, and TEM characterization, surface oxidation of GaN-for example, upon contact to ambient air atmosphere-creates an oxidative amorphous layer which provides the sites for the sensing toward CO. Treating this powder under dry ammonia at 800 °C converts the oxide layer in nitride, and consequently the sensing performance toward CO is dramatically reduced for ammonia treated GaN gas sensors. Hence the response of GaN sensors to CO is caused by oxygen in the form of amorphous surface oxide or oxynitride.