Modified maxillomandibular advancement surgery for the treatment of obstructive sleep apnoea: a scoping review.

Modified maxillomandibular advancement (MMMA) has been proposed as an alternative to the classic maxillomandibular advancement (MMA) in East and Southeast Asian populations in which bimaxillary protrusion is a prevalent trait. The key difference between MMMA and MMA is the inclusion of anterior segmental osteotomies to reduce the protrusion of the perioral region. The aim of this scoping review was to identify the variations in MMMA and treatment outcomes. A search was conducted in the PubMed, Embase, and Cochrane electronic databases for articles published up to January 2023. Ten articles were included in this review. Three variations of MMMA have been reported in the literature. Treatment outcomes have mostly been favourable for all of these variations. Mandibular advancement of >10 mm and a greater than 50% reduction in the apnoea-hypopnoea index (AHI) have been well reported. Improvements in other outcome measures, such as enlargement of the airway dimension on computed tomography and the Epworth Sleepiness Scale score, have also been shown. Despite additional surgical procedures, complications have been uncommon and mostly minor in nature. It is necessary to be cognizant of MMMA and its variations when providing sleep surgery for East and Southeast Asian patients, tailoring this to the patient's profile and needs.

Committee machines-a universal method to deal with non-idealities in memristor-based neural networks.

Artificial neural networks are notoriously power- and time-consuming when implemented on conventional von Neumann computing systems. Consequently, recent years have seen an emergence of research in machine learning hardware that strives to bring memory and computing closer together. A popular approach is to realise artificial neural networks in hardware by implementing their synaptic weights using memristive devices. However, various device- and system-level non-idealities usually prevent these physical implementations from achieving high inference accuracy. We suggest applying a well-known concept in computer science-committee machines-in the context of memristor-based neural networks. Using simulations and experimental data from three different types of memristive devices, we show that committee machines employing ensemble averaging can successfully increase inference accuracy in physically implemented neural networks that suffer from faulty devices, device-to-device variability, random telegraph noise and line resistance. Importantly, we demonstrate that the accuracy can be improved even without increasing the total number of memristors.

Retraction Note: Targeted suicide gene therapy for glioma using human embryonic stem cell-derived neural stem cells genetically modified by baculoviral vectors.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Psychogenic coma after dental surgery under general anaesthesia.

Delayed awakening after general anaesthesia due to psychogenic coma is a phenomenon that rarely presents to the oral and maxillofacial surgeon. A case of psychogenic coma following general anaesthesia for dental extractions is presented here. It is recommended that patients at risk of conversion disorder should be counselled about the risks of psychogenic coma. Early diagnosis of this condition could lead to better patient management.

Intrinsic Resistance Switching in Amorphous Silicon Suboxides: The Role of Columnar Microstructure.

We studied intrinsic resistance switching behaviour in sputter-deposited amorphous silicon suboxide (a-SiO x ) films with varying degrees of roughness at the oxide-electrode interface. By combining electrical probing measurements, atomic force microscopy (AFM), and scanning transmission electron microscopy (STEM), we observe that devices with rougher oxide-electrode interfaces exhibit lower electroforming voltages and more reliable switching behaviour. We show that rougher interfaces are consistent with enhanced columnar microstructure in the oxide layer. Our results suggest that columnar microstructure in the oxide will be a key factor to consider for the optimization of future SiOx-based resistance random access memory.

The potential application of a transcriptionally regulated oncolytic herpes simplex virus for human cancer therapy.

BACKGROUND: Emerging studies have shown the potential benefit of arming oncolytic viruses with therapeutic genes. However, most of these therapeutic genes are placed under the regulation of ubiquitous viral promoters. Our goal is to generate a safer yet potent oncolytic herpes simplex virus type-1 (HSV-1) for cancer therapy. METHODS: Using bacterial artificial chromosome (BAC) recombineering, a cell cycle-regulatable luciferase transgene cassette was replaced with the infected cell protein 6 (ICP6) coding region (encoded for UL39 or large subunit of ribonucleotide reductase) of the HSV-1 genome. These recombinant viruses, YE-PC8, were further tested for its proliferation-dependent luciferase gene expression. RESULTS: The ability of YE-PC8 to confer proliferation-dependent transgene expression was demonstrated by injecting similar amount of viruses into the tumour-bearing region of the brain and the contralateral normal brain parenchyma of the same mouse. The results showed enhanced levels of luciferase activities in the tumour region but not in the normal brain parenchyma. Similar findings were observed in YE-PC8-infected short-term human brain patient-derived glioma cells compared with normal human astrocytes. intratumoural injection of YE-PC8 viruses resulted in 77% and 80% of tumour regression in human glioma and human hepatocellular carcinoma xenografts, respectively. CONCLUSION: YE-PC8 viruses confer tumour selectivity in proliferating cells and may be developed further as a feasible approach to treat human cancers.

Targeted suicide gene therapy for glioma using human embryonic stem cell-derived neural stem cells genetically modified by baculoviral vectors.

Tumor-tropic neural stem cells (NSCs) can be used in the Trojan horse approach as cellular vehicles for targeted delivery of therapeutic agents to distant tumor sites. To realize this cancer therapy potential, it is important to have a renewable source to generate large quantities of uniform human NSCs. Here, we reported that NSCs derived from HES1 human embryonic stem cell line were capable of migrating into intracranial glioma xenografts after systemic injection or after intracranial injection at a site distant from the tumor. To test whether the HES1-derived NSCs can be used for cancer gene therapy, we used a baculoviral vector to introduce the herpes simplex virus thymidine kinase suicide gene into the cells and demonstrated that baculovirus-mediated transgene expression may last for at least 3 weeks in NSCs. After being injected into the cerebral hemisphere opposite the tumor site and in the presence of ganciclovir, NSCs expressing the suicide gene were able to inhibit the growth of human glioma xenografts and prolong survival of tumor-bearing mice. Our findings suggest that human embryonic stem cells could potentially serve as a clinically viable source for production of cellular vehicles suitable for targeted anticancer gene therapy.

Diffusion-weighted MR imaging: diagnosing atypical or malignant meningiomas and detecting tumor dedifferentiation.

BACKGROUND AND PURPOSE: Atypical and malignant meningiomas are uncommon tumors with aggressive behavior and higher mortality, morbidity, and recurrence compared with benign tumors. We investigated the utility of diffusion-weighted (DW) MR imaging to differentiate atypical/malignant from benign meningiomas and to detect histologic dedifferentiation to higher tumor grade. MATERIALS AND METHODS: We retrospectively compared conventional and DW MR images (b-value 1000 s/mm(2)) acquired on a 1.5T clinical scanner between 25 atypical/malignant and 23 benign meningiomas. The optimal cutoff for the absolute apparent diffusion coefficient (ADC) and normalized ADC (NADC) ratio to differentiate between the groups was determined by using receiver operating characteristic (ROC) analysis. RESULTS: Irregular tumor margins, peritumoral edema, and adjacent bone destruction occurred significantly more often in atypical/malignant than in benign meningiomas. The mean ADC of atypical/malignant meningiomas (0.66 +/- 0.13 x 10(-3) mm(2)/s) was significantly lower compared with benign meningiomas (0.88 +/- 0.08 x 10(-3) mm(2)/s; P < .0001). Mean NADC ratio in the atypical/malignant group (0.91 +/- 0.18) was also significantly lower than the benign group (1.28 +/- 0.11; P < .0001), without overlap between groups. ROC analysis showed that ADC and NADC thresholds of 0.80 x 10(-3) mm(2)/s and 0.99, respectively, had the best accuracy: at the NADC threshold of 0.99, the sensitivity and specificity were 96% and 100%, respectively. Two patients had isointense benign tumors on initial DW MR imaging, and these became hyperintense with the decrease in ADC and NADC below these thresholds when they progressed to atypical and malignant meningiomas on recurrence. CONCLUSIONS: ADC and NADC ratios in atypical/malignant meningiomas are significantly lower than in benign tumors. Decrease in ADC and NADC on follow-up imaging may suggest dedifferentiation to higher tumor grade.

A simple and cost-effective method of fixation of deep brain stimulation (DBS) electrode.

Unplanned migration of a deep brain stimulation (DBS) electrode after accurate placement at the intended target can result in a poor surgical outcome and added cost to the procedure. There are various fixation methods described in the literature. The authors describe the use of a modified burr-hole cover which serves as a simple and cost-effective method of fixation of the DBS lead with excellent results.

An active surveillance study of vancomycin-resistant Enterococcus in Queen Elizabeth Hospital, Hong Kong.

OBJECTIVE: To assess the rate of faecal vancomycin-resistant Enterococcus colonisation in high-risk patients in a regional hospital. DESIGN: Prospective observational surveillance study. SETTING: Queen Elizabeth Hospital, Hong Kong. PATIENTS: From September 2001 to December 2002, stool samples from patients in the intensive care unit and patients in whom Clostridium difficile testing was requested were used for study using a broth enrichment method. MAIN OUTCOME MEASURES: Number of faecal vancomycin-resistant Enterococcus colonisation. RESULTS: A total of 2414 cultures from 1792 patients were tested for vancomycin-resistant Enterococcus using a broth enrichment method. Only one (0.06%) patient was found to harbour a vancomycin-resistant Enterococcus faecalis in the gastro-intestinal tract. Surveillance cultures from contacts of the case revealed another six with vancomycin-resistant Enterococcus faecalis. Vancomycin-resistant Enterococcus faecalis was also later reported from a clinical specimen (catheterized urine) of another patient. They were all epidemiologically linked to the index case. Mean inhibitory concentrations of vancomycin and teicoplanin were determined to be higher than 256 and 0.5 microgram/mL, respectively by E-test for all the vancomycin-resistant Enterococcus isolates. Polymerase chain reaction analysis confirmed the presence of vanB genes and the result was in line with the phenotype. Pulsed-field gel electrophoresis confirmed a monoclonal vancomycin-resistant Enterococcus outbreak. Strict infection control measures recommended by the Centers for Disease Control and Prevention were followed and the outbreak was successfully controlled. CONCLUSION: Vancomycin-resistant Enterococcus colonisation is rare, but present among high-risk patients in our hospital. A routine surveillance programme should be implemented that will enable early case detection and prompt initiation of infection control measures to prevent the emergence of an endemic situation.

A case-control study of SARS versus community acquired pneumonia.

The clinical, laboratory, and radiological features at presentation of 16 children (<12 years) with severe acute respiratory syndrome (SARS) and pneumonia were compared with 32 age matched patients with community acquired pneumonia for determination of predictive factors that could allow early differentiation of the two conditions. A definitive contact history was the most important predictor for SARS. Raised serum lactate dehydrogenase concentration in the presence of low neutrophil count and serum creatine phosphokinase level at presentation also indicated an increased likelihood of SARS-coronavirus infection in young children.

Role of imaging in management of hemophilic patients.

OBJECTIVE: The purpose of this study was to evaluate the role of symptomatology and conventional radiographic scoring in predicting synovial hypertrophy, which could affect the clinical management of hemophilic patients. MATERIALS AND METHODS: Twenty males (mean age, 14.3 years old) with hemophilic arthropathy, including 34 symptomatic joints and 26 asymptomatic joints (16 knees, 20 ankles, and 24 elbows) had conventional radiographs of individual joints obtained that were rated according to the Arnold-Hilgartner stage and the Pettersson score. The patients also underwent MRI for the detection of synovial hypertrophy. The association of synovial hypertrophy and symptomatology was evaluated using the chi-square or Fisher's exact test. The best sensitivity, specificity, and positive and negative predictive values in detection of synovial hypertrophy using symptomatology and radiographic scoring were calculated. RESULTS: A significant association was seen between symptomatology and synovial hypertrophy of the knee and ankle joints (p < 0.05). The sensitivity, specificity, and positive and negative predictive values of symptomatology in detection of synovial hypertrophy of the knee were 100%, 78%, 78%, and 100%, respectively, and for the ankle were 83%, 75%, 83%, and 75%, respectively. The Arnold-Hilgartner stage and Pettersson score of the radiograph had a significant association with synovial hypertrophy of the knee and ankle joints (p < 0.05). Arnold-Hilgartner staging provided a better prediction of synovial hypertrophy, with sensitivity, specificity, positive predictive value, and negative predictive value of 100%, 100%, 100%, and 100% for knees and 82%, 100%, 100%, and 82% for ankles. CONCLUSION: In hemophilic patients, the presence of symptomatology in the knee and ankle joints is associated with synovial hypertrophy, and scoring of the conventional radiographs using Arnold-Hilgartner staging is useful for the prediction of synovial hypertrophy.

Non-traumatic spontaneous acute epidural haematoma -- report of two cases and review of the literature.

Epidural haematomas are usually associated with preceding head trauma. The entity of non-traumatic spontaneous acute epidural haematoma is rare and most commonly occurs in the presence of infectious disease. It can also occur in the presence of coagulopathy, vascular malformations of the dura mater and haemorrhagic tumours. Sickle cell disease, systemic lupus erythematosus, open heart surgery and haemodialysis have also been implicated as causative factors. The authors report two cases of spontaneous epidural haematomas (one of unknown aetiology and one from a coagulation disorder) and discuss the aetiological agents involved in this rarely described condition.

Comparison of breath-hold 2D phase-contrast with non breath-hold cine phase-contrast MRA in the assessment of azygos venous blood flow in portal hypertension.

Azygos venous blood flow as an index of blood flow through the gastroesophageal collaterals and varices is of value in the prediction of gastrointestinal bleeding. Measurement of azygos venous blood flow has been achieved by non breath-hold (NBH) cine phase-contrast magnetic resonance imaging. The objective of this study was to compare the faster breath-hold (BH) phase-contrast technique with the standard (NBH) cine phase-contrast technique in the measurement of azygos blood flow. Thirty-two cirrhotic patients with esophageal varices were examined by magnetic resonance imaging using a BH technique and a NBH cine phase-contrast technique to measure the flow velocity, flow volume and calibre of the azygos vein at the mid-right atrial level. The flow values were obtained on the velocity image of the phase-contrast study. Values obtained from the two methods were evaluated statistically for the strength and significance of correlation by the Pearson test. Measurement by the BH method performed at full-inspiration as well as end-expiration was also obtained in 15 healthy volunteers. The breath-hold phase-contrast method has significant but weak correlation with non BH cine phase-contrast method in the measurement of azygos venous blood flow volume (r = 0.55, p < 0.01) and flow velocity (r = 0.43, p = 0.01). However, the calibre of the azygos vein gave a strong correlation in these two methods (0.82). In the subgroup of patients whose azygos blood flow velocity was greater than 7.4 cm/s, the correlation of azygos blood flow volume is strong (r = 0.80, p < 0.01). The azygos vein calibre remains highly correlated between the BH and NBH method, in both high flow velocity (r = 0.73) and low flow velocity (r = 0.83) groups. Breath-hold sequence leads to higher values for flow velocity and flow volume in the cirrhotic patients and also the control group. In patients with portal hypertension, BH 2D phase-contrast (PC) magnetic resonance angiography (MRA) could give a comparable estimation of the calibre of the azygos vein as the NBH 2D cine PC MRA but not for azygos flow volume. In patients with high azygos flow velocity, the strong correlation in flow volume between the BH and NBH method suggests that the BH method may be a time-saving alternative to the NBH method.

Correlation between annual change in health status and computer tomography derived lung density in subjects with alpha1-antitrypsin deficiency.

BACKGROUND: There is increasing recognition that questionnaires of health status and lung density measurements are more sensitive tools for assessing progression of emphysema than forced expiratory volume in 1 second (FEV(1)) and transfer coefficient (KCO). A study was undertaken to investigate prospectively the correlation between annual change in health status and computer tomography (CT) derived lung density in subjects with alpha(1)-antitrypsin deficiency. METHODS: Twenty two patients of mean (SD) age 40.7 (9.2) years with ZZ type alpha(1)-antitrypsin deficiency were investigated at baseline and 30 months later by FEV(1) and KCO, St George Respiratory Questionnaire (SGRQ), and by a spiral CT scan of the chest. CT data of chest images were analysed using software designed for automated lung contour detection and lung density measurements. The density data were corrected for changes in inspiration levels. RESULTS: Changes in lung density, expressed as 15th percentile point or relative area below -950 HU, correlated well with changes in health status (SGRQ total score): R = -0.56, p = 0.007 or R = 0.6, p = 0.003. Neither changes in health status nor changes in lung density correlated significantly with changes in FEV(1) or changes in KCO. CONCLUSIONS: The SGRQ total score (which is a global measure in COPD) and lung density (a specific measure of emphysema) are sensitive to deterioration in patients with alpha(1)-antitrypsin deficiency. This finding may facilitate future studies with new drugs specific for emphysema, a frequently occurring component of COPD.

Clinics in diagnostic imaging (89). Infantile hepatosplenic haemangioendotheliomas.

The ultrasonographical and computed tomography findings of a six-month-old female infant with haemangioendotheliomas of the liver and spleen are described. The splenic lesion had an unusual ultrasonographical appearance of a well-defined isoechoic mass with a hypoechoic rim. Diagnosis was confirmed by histological examination of the hepatic biopsy specimen. Hepatosplenic lesions in the first year of life may be due to a variety of pathological processes. It is important to include haemangioendotheliomas in the differential diagnosis of hepatosplenic masses in an infant.

Giant aneurysm treated by bilateral cervical carotid artery to proximal middle cerebral artery bypass and balloon embolisation: a case report.

The authors describe a case of a 59 year-old Chinese lady with a history of spontaneous left caroticocavernous fistula in 1988 treated by left internal carotid artery clipping and muscle embolisation. She subsequently presented with a subarachnoid haemorrhage in November 1997 secondary to rupture of an unclippable giant right internal carotid artery aneurysm. This was treated satisfactorily with bilateral cervical carotid artery to proximal middle cerebral artery bypass followed by balloon occlusion. Postoperatively, the patient has no neurological deficit and CT angiogram shows good patency of both grafts 6 months after surgery.

Tethered cord syndrome preceding syrinx formation--serial radiological documentation.

The authors report a case of tethered cord syndrome preceding the development of a syrinx, which subsequently resolved with detethering. This was shown conclusively with serial radiological imaging, although the patient did not improve clinically. The lack of clinical improvement is likely to be due to the delay in surgery caused by infections in this patient, and early detethering should therefore be the aim in patients with tethered cord syndrome.

Nitric oxide and subarachnoid hemorrhage: elevated level in cerebrospinal fluid and their implications.

OBJECTIVE: Nitric oxide (NO) plays an important role in the pathogenesis of neuronal injury after brain ischemia, and decreased levels of NO have been implicated in the pathogenesis of vasospasm after subarachnoid hemorrhage (SAH). In this study, we measured the ventricular cerebrospinal fluid (CSF) NO levels in patients with SAH and correlated the levels with clinical grade and middle cerebral artery velocities measured with transcranial Doppler ultrasound. METHODS: All patients with spontaneous SAH documented on computed tomography and with an external ventricular drain inserted within 24 hours of hemorrhage were included in the study. A total of 16 patients were studied between August 1999 and August 2000. CSF was collected serially at the time of surgery and subsequently at daily intervals. It was collected during the time that the external ventricular drain remained patent and in situ. NO levels were measured by photometric analysis by using a nitrite/nitrate assay kit (Cayman Chemical, Ann Arbor, MI). RESULTS: The peak NO level in patients with SAH ranged from 9.96 to 168.16 micromol, with a median of 36.93 micromol. The levels were significantly elevated as compared with the control group (5.16 micromol, P < 0.05). The median NO level in patients with poor-grade SAH was 67.14 micromol as compared with 27.42 micromol in patients with good-grade hemorrhage (P < 0.05). No correlation was seen between CSF NO levels and middle cerebral artery velocities. The median NO level was 33.2 micromol in patients with a poor outcome as compared with 30.25 micromol in patients with a good outcome (P > 0.05). CONCLUSION: This study showed that NO levels are elevated after spontaneous SAH, and the degree of elevation is higher in patients with poor-grade SAH.

Simple, at-site detection of diethylene glycol/ethylene glycol contamination of glycerin and glycerin-based raw materials by thin-layer chromatography.

This paper describes a rapid, inexpensive thin-layer chromatographic (TLC) method that separates diethylene glycol (DEG) from glycerin and other glycols. Studies with collaborating laboratories of the World Health Organization have shown that about 6% DEG in glycerin and about 2% DEG in acetaminophen (paracetamol) elixirs may be detected by direct visual inspection of the developed TLC sheets. Staining the sheet permits detection of DEG at less than 0.1%. The method costs less than $1.00 per test and takes 20 min by visual inspection, longer when staining is required. The visual method can be performed without laboratory facilities by personnel having little previous training. Samples testing positive by the visual method can be submitted to a laboratory for confirmation and quantitation of DEG.