How to reduce the complication rate of multiple burr holes surgery in moyamoya angiopathy.

PURPOSE: This study is aimed at analyzing clinical outcome, absence of stroke recurrence, revascularization, and complications and long-term follow-up in the surgical treatment of moyamoya angiopathy (MMA) using the multiple burr holes (MBH) technique with dura opening and arachnoid preservation as a single procedure. To the best of our knowledge, this is the first to describe an MBH technique with arachnoid preservation. METHOD: We retrospectively reviewed all patients operated from June 2001 to March 2021, for a symptomatic and progressive MMA operated with opening of the dura but arachnoid preservation. Clinical examinations were obtained in all patients, and radiological monitoring was performed by cerebral 3D-magnetic resonance angiography (MRA) with perfusion or single-photon emission computed tomography (SPECT) with acetazolamide. RESULTS: In total, 21 consecutive patients (6 children and 15 adults) were included with a mean age of 7.4 years in the pediatric group and 36.9 years in the adult group. Initial presentation was permanent ischemic stroke in 15 cases, transient ischemic attack (TIA) in 5 cases, and cerebral hemorrhage in one case. The MBH with dura opening and arachnoid preservation was performed bilaterally in 9 cases (43%) and unilaterally in 12 cases (57%). One patient died due to intraoperative bilateral ischemic stroke. Of the 20 other patients, 30% demonstrated clinical stability and 70% showed partial or complete recovery. Although one patient experienced a perioperative stroke, we did not observe any pseudomeningocele or postoperative ischemic stroke (IS) recurrence in all surviving cases during the average follow-up period of 55.5 months (range: 1-195). These outcomes emphasize the importance of preoperative monitoring to ensure the effectiveness and safety of the intervention. Postoperative angiography studies showed revascularization in 96.3% of treated hemispheres (100% in the adult group vs 80% in the pediatric group). CONCLUSIONS: Our results on this small cohort suggest that the MBH technique with opening of the dura and arachnoids preservation can prevent recurrent strokes and reduce the risk of pseudomeningocele.

The impact of influenza vaccination on infection, hospitalisation and mortality in the Netherlands between 2003 and 2015.

Influenza epidemics annually cause substantial morbidity and mortality. For this reason, vaccination is offered yearly to persons with an elevated risk for complications. Assessments of the impact of vaccination are, however, hampered by year-to-year variation in epidemic size and vaccine effectiveness. We estimate the impact of the current vaccination programme comparing simulations with vaccination to counterfactual simulations without vaccination. The simulations rely on an age- and risk-structured transmission model that tracks the build-up and loss of immunity over successive seasons, and that allows the vaccine match to vary between seasons. The model parameters are estimated with a particle Monte Carlo method and approximate Bayesian computation, using epidemiological data on vaccine effectiveness and epidemic size in the Netherlands over a period of 11 years. The number of infections, hospitalisations and deaths vary greatly between years because waning of immunity and vaccine match may differ every season, which is in line with observed variation in influenza epidemic sizes. At an overall coverage of 21%, vaccination has averted on average 13% (7.2-19%, 95% range) of infections, 24% (16-36%) of hospitalisations, and 35% (16-50%) of deaths. This suggests that vaccination is mainly effective in protecting vaccinees from infection rather than reducing transmission. As the Dutch population continues to grow and age, the vaccination programme is projected (up to 2025) to gain in impact, despite a decreasing infection attack rate.

Vaccinating children against influenza increases variability in epidemic size.

Seasonal influenza causes a high disease burden. Many influenza vaccination programmes target the elderly and persons at high risk of complications. Some countries have recommended or even implemented a paediatric vaccination programme. Such a programme is expected to reduce influenza transmission in the population, offering direct protection to the vaccinated children and indirect protection to the elderly. We study the impact of a child vaccination programme with an age- and risk-structured transmission model, calibrated to data of 11 influenza seasons in the Netherlands. The model tracks the build-up of immunes and susceptibles in each age cohort over time, and it allows for seasonal variation in vaccine match and antigenic drift. Different vaccination strategies are evaluated for three target age groups (2-3, 2-12 and 2-16 year olds) over the full range of vaccination coverages (0-100%). The results show that the paediatric vaccination programme has only a limited impact on the elderly age groups, which account for most influenza morbidity and mortality. This is due to two notable changes in infection dynamics. First, an age shift is observed: influenza infections are reduced in vaccinated children, but are increased in young adults with limited natural immunity after years of vaccination. These young adults assume the role of driving the epidemic. Second, a year with low influenza activity can be followed by a large epidemic due to build-up of susceptibles. This variation of the infection attack rate increases with increasing vaccination coverage. The increased variability in the infection attack rate implies that health care facilities should be prepared for rare but larger peaks in influenza patients. Moreover, vaccinating the group with the highest transmission potential, results in a larger dependency on a secure vaccine supply. These arguments should be taken into account in the decision to introduce mass vaccination of school-aged children against influenza.

Learning curve of medialization thyroplasty using a Montgomery™ implant.

UNLABELLED: Type I thyroplasty--also called medialization thyroplasty (MT)--is considered as an effective treatment for glottic incompetence in general and for abductor vocal fold palsy in particular. In the past there have been some concerns about the experience a laryngeal framework surgeon should have in order achieve an acceptable voice outcome. To assess the learning curve of MT performed using the Montgomery(®) hard silicone implant. A retrospective study involving 36 patients divided into three consecutive groups (1, 2, 3) of 12 MT patients or six consecutive groups (1a, 1b, 2a, 2b, 3a, 3b) of six MT patients. OUTCOME MEASURES: acoustic and aerodynamic outcome improvements (δ) compared to the duration of intervention [operative times (OT)]. Data were analysed by Anova, Kuskal Wallis and χ (2) statistical tests, according to data distributions. OT decreased significantly between groups 1, 2 and 3 with a mean OT of 90.5', 71.5' and 56' (p < 0.001), respectively. Objective δ such as maximum phonation time (MPT) (p 0.376), Estimated Sub-Glottic Pressure (ESPG) (p: 0.675) Shimmer (p: 0.543) and Jitter (p: 0.709) did not show significant improvement. Only the voice handicap index (VHI) δ of group 2 showed significant improvement (p 0.005) compared with the two other groups 1 and 3. Surgeon experience decreases the OT significantly. On the other hand, our study did not show a correlation between surgeon experience and voice outcome measures improvemnts (MPT, ESGP, Shimmer, Jitter).

Massive postoperative pulmonary embolism in a young woman using oral contraceptives: the value of a preoperative anesthetic consult.

We describe the case of a woman with a history of active tabagism and on the oral contraceptive Yasmin, presenting in the Post-Anesthesia Care Unit (PACU) with a cardiac arrest due to massive pulmonary embolism following transforaminal lumbar interbody fusion surgery. The patient had preoperatively several risk factors for deep venous thrombosis. This case-report emphasizes the value of a preoperative anesthetic visit and eventual temporary cessation of certain oral contraceptives in specific cases.

An innovative approach to tracheotomy in patients with major obstruction of the upper airway.

BACKGROUND: Patients with severe dyspnea consecutive to locally advanced obstructive head and neck squamous cell carcinoma (HNSCC) or subglottic stenosis requiring definitive or temporary tracheotomy are frequently difficult to ventilate and intubate. MATERIALS AND METHODS: We describe a new procedure to perform tracheotomy easily and safely in patients with major obstruction of the upper airway. A catheter, specifically designed for cricothyroidotomy, was inserted into the trachea under local anesthesia. Then, general anesthesia was induced and the catheter was used as a guide for dilatation tracheotomy. From November 2009 to March 2013, the procedure was successfully used in 13 consecutive patients. Twelve out of 13 patients presented severe inspiratory dyspnea and stridor. RESULTS: During and after the procedure, no complications were reported. CONCLUSIONS: The reported technique is quickly performed and is a safe way to ensure short and long time ventilation of patients with major obstruction of the upper airway.

Transient perioperative visual loss after an elective neurosurgical procedure.

OBJECTIVE: To describe a case of reversible visual loss after a neurosurgical intervention and to discuss the role of the prone position as a potential risk factor. OBSERVATION: A 63-year-old woman without significant medical previous history underwent elective resection of a left parieto-occipital meningioma. Preoperatively, the patient presented a right homonymous lower quadranopsia. The surgical procedure was not complicated. The patient was positioned in prone with a mild inclination of the table in reverse Trendelenburg position. The head was maintained in a Mayfield skull clamp, and ocular compression was excluded. There was no significant hypotension, hemodilution or vasopressors infusion during the procedure. Immediately after recovery from anesthesia, the patient experienced total blindness and flash visual evoked potentials confirmed the absence of retinal, primary or late occipital activities. A progressive, but finally complete recovery started after 24 hours. CONCLUSION: This case illustrates the individual risk for visual injury after the prone position during some neurosurgical interventions.

Exposure of uninfected poultry farms to HPAI (H7N7) virus by professionals during outbreak control activities.

With an extensive data set on visits made to control the H7N7 avian influenza epidemic in The Netherlands in 2003 we investigate the potential role of the persons involved in the control activities as vectors for disease transmission. We hypothesized that people can spread the virus on the same day mechanically, or till 10 days if they have become infected themselves. Taken into account was the estimated time of introduction of the virus into a poultry flock back-calculated from mortality data. We identified 19 visits from a person that went on the same day from an infected (source) farm to a (target) farm that was before infection and a further 197 visits were made to (target) farms that remained uninfected. Of the 19 visits, eight were made within 3 days before an infection started on the target farm. If we assume that these eight visits were the primary reason the visited farms became infected, then we can calculate an upper estimate for the probability of transmission by a person per visit of 0.037. In addition we identified visits were a person first visited an infected source farm and up to 10 days after visited a target farm that either remained uninfected or was before infection. Most visits to infected source farms were made just after infection. Animals on these farms were likely not yet symptomatic, thus escaping diagnosis. Such events may be difficult to prevent, although awareness of this possibility is already a major step towards prevention. Most of these visits involved tracing and screening and were made by a relatively small number of trained veterinarians. This makes it possible to focus training efforts specifically on these persons and make sure they stringently use the personal protective equipment and strictly follow the hygiene protocol, to protect them and prevent them from spreading the disease.

An inactivated H5N2 vaccine reduces transmission of highly pathogenic H5N1 avian influenza virus among native chickens.

Vaccination against H5N1 highly pathogenic avian influenza in endemically affected areas is a potentially attractive option for local prevention and control. In Indonesia the majority of local outbreaks have occurred in back yard flocks with native chickens, and it is therefore of interest to determine whether these birds can be protected against infection by vaccination. To this end two transmission experiments were carried out with H5N1 virus (A/chicken/Legok/2003) in vaccinated and unvaccinated native chickens. The vaccine contained an inactivated heterologous H5N2 strain (A/turkey/England/N28/73 H5N2). Birds were vaccinated at 4 and 7 weeks of age and challenged at 10 weeks of age. During 10 days post-challenge tracheal and cloacal swabs were taken for virus isolation, and serum blood was collected regularly to measure haemaglutinin inhibiting (HI) antibody responses. The results show that transmission of H5N1 virus was rapid and efficient in unvaccinated birds, that infection and transmission were completely prevented in vaccinated birds, and that vaccinated birds that were exposed to unvaccinated inoculated birds were still protected from infection. These findings indicate that vaccination with a heterologous H5N2 vaccine is able to prevent virus transmission in flocks of native chickens.

The role of backyard poultry flocks in the epidemic of highly pathogenic avian influenza virus (H7N7) in the Netherlands in 2003.

In recent years, outbreaks of highly pathogenic avian influenza (HPAI) viruses have caused the death of millions of poultry and of more than 200 humans worldwide. A proper understanding of the transmission dynamics and risk factors for epidemic spread of these viruses is key to devising effective control strategies. The aim of this study was to quantify the epidemiological contributions of backyard flocks using data from the H7N7 HPAI epidemic in the Netherlands in 2003. A dataset was constructed in which flocks in the affected area were classified as susceptible (S), infected but not yet infectious (E), infectious (I), and removed (R). The analyses were based on a two-type SEIR epidemic model, with the two types representing commercial poultry farms and backyard poultry flocks. The analyses were aimed at estimation of the susceptibility (g) and infectiousness (f) of backyard flocks relative to commercial farms. The results show that backyard flocks were considerably less susceptible to infection than commercial farms (g = 0.014; 95%CI = 0.0071-0.023), while estimates of the relative infectiousness of backyard flocks varied widely (0 < or = f < or =5). Our results indicate that, from an epidemiological perspective, backyard flocks played a marginal role in the outbreak of highly pathogenic avian influenza in the Netherlands in 2003.

Office-based anesthesia in Belgium?

For many years, office based anesthesia (OBA), has been considerably increasing in the US. This type of practice is starting to develop in Belgium. On the other side of the atlantic, legislation concerning this practice is becoming more and more precise, whereas the same isn't true in our country. It seems therefore opportune to try and define the different points of view. This article will define the position of the legislator, insurance companies and finally, of the professional organizations. OBA practice is developping insidiously here, and we should therefore ask ourselves serious questions regarding the legal repercussions that it could have. To conclude, we can say that if for a couple of years, the US have started to legislate and propose guidelines, as well as creating special accreditation organizations to inspect and advise the offices, the same is not the case in Belgium. The OBA phenomenon arrived much later here and is really at its very beginnings, but it seems however important to anticipate and clearly regulate this practice in our country.

PEGylated cholecystokinin prolongs satiation in rats: dose dependency and receptor involvement.

BACKGROUND AND PURPOSE: Acute intraperitoneal (i.p.) administration of cholecystokinin (CCK) is known to induce a significant, but short-lasting, reduction in food intake, followed by recovery within hours. Therefore, we had covalently coupled CCK to a 10 kDa polyethylene glycol and showed that this conjugate, PEG-CCK(9), produced a significantly longer anorectic effect than unmodified CCK(9). The present study assessed the dose-dependency of this response and the effect of two selective CCK(1) receptor antagonists, with different abilities to cross the blood-brain barrier (BBB), on PEG-CCK(9)-induced anorexia. EXPERIMENTAL APPROACH: Food intake was measured, for up to 23 h, after i.p. administration of different doses (2, 4, 8, 16 and 32 microg kg(-1)) of CCK(9) or PEG-CCK(9) in male Wistar rats. Devazepide (100 microg kg(-1)), which penetrates the BBB or 2-NAP (3 mg kg(-1)), which does not cross the BBB, were coadministered i.p. with PEG-CCK(9) (6 microg kg(-1)) and food intake was monitored. KEY RESULTS: In PEG-CCK(9)-treated rats, a clear dose-dependency was seen for both the duration and initial intensity of the anorexia whereas, for CCK(9), only the initial intensity was dose-dependent. Intraperitoneal administration of devazepide or 2-NAP, injected immediately prior to PEG-CCK(9), completely abolished the anorectic effect of PEG-CCK(9). CONCLUSIONS AND IMPLICATIONS: The duration of the anorexia for PEG-CCK(9) was dose-dependent, suggesting that PEGylation of CCK(9) increases its circulation time. Both devazepide and 2-NAP completely abolished the anorectic effect of i.p. PEG-CCK(9) indicating that its anorectic effect was solely due to stimulation of peripheral CCK(1) receptors.

Effect of vaccination on transmission of HPAI H5N1: the effect of a single vaccination dose on transmission of highly pathogenic avian influenza H5N1 in Peking ducks.

The highly pathogenic H5N1 avian influenza virus is widespread among domestic ducks throughout Southeast Asia. Many aspects of the poultry industry and social habits hinder the containment and eradication of AI. Vaccination is often put forward as a tool for the control of AI. However, vaccination will only lead to eradication when it reduces the virus spread to such an extent that herd immunity is obtained. To study the effect of a single vaccination dose on the transmission of H5N1 in domestic ducks we performed experiments in which infected and uninfected ducks were housed together and the infection chain was monitored by means of virus isolation and serology. Specifically, Peking ducks were vaccinated with A/Chicken/Mexico/232/94/ CPA H5N2 and challenged with A/Chicken/GxLA/1204/04 H5N1 one week after vaccination. In both the control and vaccinated groups all inoculated and contact animals were quickly infected. However, the disease signs and mortality differed between the control and treatment groups. This finding may have important implications for the control of H5N1 by means of vaccination.

Quantification of the effect of vaccination on transmission of avian influenza (H7N7) in chickens.

Recent outbreaks of highly pathogenic avian influenza (HPAI) viruses in poultry and their threatening zoonotic consequences emphasize the need for effective control measures. Although vaccination of poultry against avian influenza provides a potentially attractive control measure, little is known about the effect of vaccination on epidemiologically relevant parameters, such as transmissibility and the infectious period. We used transmission experiments to study the effect of vaccination on the transmission characteristics of HPAI A/Chicken/Netherlands/03 H7N7 in chickens. In the experiments, a number of infected and uninfected chickens is housed together and the infection chain is monitored by virus isolation and serology. Analysis is based on a stochastic susceptible, latently infected, infectious, recovered (SEIR) epidemic model. We found that vaccination is able to reduce the transmission level to such an extent that a major outbreak is prevented, important variables being the type of vaccine (H7N1 or H7N3) and the moment of challenge after vaccination. Two weeks after vaccination, both vaccines completely block transmission. One week after vaccination, the H7N1 vaccine is better than the H7N3 vaccine at reducing the spread of the H7N7 virus. We discuss the implications of these findings for the use of vaccination programs in poultry and the value of transmission experiments in the process of choosing vaccine.

Prolonged persistence of bovine herpesvirus in small cattle herds: a model-based analysis.

Herpesviruses can remain dormant in once-infected hosts and, upon reactivation, cause such hosts to become infectious. This phenomenon of latency and reactivation may enable herpesviruses to persist for a long time in small host populations. To quantify the effect of reactivation on persistence, the time to extinction of bovine herpesvirus type 1 (BHV-1) in small cattle populations was calculated. For realistic parameter values the mean time to extinction is already more than 100 years in a population of 10 animals. In a population of 20 animals the time to extinction is approximately 2000 years. The effects of vaccination on persistence were also studied, revealing that continued vaccination of the whole population could result in much faster eradication. For instance, in an isolated herd of 20 animals BHV-1 could be eradicated in 44 years.

Investigation of fractions present in the stem bark of Annickia kummeriae on their P-glycoprotein inhibitory pump activity.

Using MCF-7R cells and rhodamine 6G as the fluorescent probe, a bioassay-targeted purification process was pursued in order to isolate the active P-gp inhibitory fractions from Annickia kummeriae. Of 24 fractions obtained in the first preparative liquid chromatography (p-LC) run, only fraction 1 exhibited activity. Further p-LC fractionation led to the separation of fraction 1 into fractions 1.1-1.8. Fractions 1.4, 1.5 and 1.6 proved to be active by inducing a significant accumulation of rhodamine 6G by 3.3-, 4.5- and 4.9-fold at 10 microg/mL, and by 5.3-, 6.3- and 6.8-fold at 100 microg/mL, respectively. Fraction 1.6 was separated into several fractions by using an analytical liquid chromatography (a-LC) system. Fractions 1.6.18, 1.6.19 and 1.6.20 were active and they induced an accumulation of rhodamine 6G by 3.0-, 1.8- and 3.5-fold at 1x microg/mL and by 4.8-, 6.7- and 6.8-fold at 10x microg/mL, respectively. Afterwards, 28.3 mg of fraction 1.6 was processed by a-LC, and fractions 1.6.18, 1.6.19 and 1.6.20 were collected separately and dried. The amounts of materials recovered were 6.2, 7.4 and <1 mg, corresponding to 21.9%, 26.1% and <3.5% of fraction 1.6, respectively. From the total amount injected and the relative masses represented by these fractions, it can be calculated that the 1x microg/mL level corresponded to ca. 35, 42 and <5 microg/mL, respectively. Fluorescence microscopy revealed that incubation of the cells with rhodamine 6G alone did not show any fluorescence, whereas cells which were incubated in medium containing rhodamine 6G together with fraction 1.4, 1.6 or reserpine, clearly indicated accumulation of the dye intracellularly. This is an indication that the active compounds effected high intracellular fluorescence by inducing accumulation of the dye in the cells through inhibition of the P-gp pump.

Comparison of the transmission characteristics of low and high pathogenicity avian influenza A virus (H5N2).

Low pathogenicity avian influenza A strains (LPAI) of the H5 and H7 type are noted for their ability to transform into highly pathogenic counterparts (HPAI). Here we compare the transmission characteristics in poultry of LPAI H5N2 (A/Chicken/Pennsylvania/83) and corresponding HPAI virus by means of transmission experiments. In the experiments, five inoculated animals are placed in a cage with five contact animals, and the infection chain is monitored by taking blood samples, and samples from the trachea and cloaca. The data are analysed by final size methods and a generalized linear model. The results show that HPAI virus is more infectious and induces a longer infectious period than LPAI. In fact, fully susceptible animals are invariably infected when confronted with HPAI virus and die within six days after infection. Animals previously infected with LPAI virus, on the other hand, survive an infection with HPAI virus or escape infection all together. This implies that a previous infection with LPAI virus effectively reduces susceptibility of the host to infection and decreases transmission of HPAI virus. We discuss the implications of these conclusions for the control and evolution of avian influenza viruses.

Transmission dynamics of low- and high-pathogenicity A/Chicken/Pennsylvania/83 avian influenza viruses.

High-pathogenicity avian influenza (HPAI) viruses emerged from low-pathogenicity avian influenza (LPAI) viruses in Pennsylvania (1983-84), Mexico (1994-95), and Italy (1999-2000). Here we focus on the question of why the HPAI virus supersedes the LPAI virus, once it has appeared during the epidemic. To study this, we used an experimental model in chickens that enabled us to estimate the reproduction ratio (R0). Using this model, we determined the R0 of the A/Chicken/Pennsylvania/21525/83 (LPAI) and of the A/Chicken/Pennsylvania/1370/83 (HPAI). Comparing the R0 of both viruses, we concluded that the R0 of the HPAI virus is significantly higher than the R0 of the LPAI.

Mechanism of simmondsin decomposition during sodium hydroxide treatment.

Jojoba seed meal shows appetite-suppressing activity due to the presence of simmondsin. This pharmacological activity disappears with treatment of the meal with sodium hydroxide. To elucidate this mechanism of inactivation, the reaction of simmondsin in 1 N NaOH at 20 degrees C was monitored as a function of time. The end products of the reaction as well as intermediates were isolated and identified. The half-life of simmondsin was approximately 60 min with d-glucose and 2-hydroxy-3-methoxyphenylacetonitrile as reaction end products. The reaction mechanism could be elucidated by the isolation of isosimmondsin and a simmondsin lactone derivative. Those compounds were isolated and purified by a combination of column chromatography and HPLC and identified mainly by HRMS and NMR spectroscopy.

Quantification of transmission in one-to-one experiments.

We study the statistical inference from data on transmission obtained from one-to-one experiments, and compare two algorithms by which the reproduction ratio can be quantified. The first algorithm, the transient state (TS) algorithm, takes the time course of the epidemic into account. The second algorithm, the final size (FS) algorithm, does not take time into account but is based on the assumption that the epidemic process has ended before the experiment is stopped. The FS algorithm is a limiting case of the TS algorithm for the situation where time tends to infinity. So far quantification of transmission has relied almost exclusively on the FS algorithm, even if the TS algorithm would have been more appropriate. Its practical use, however, is limited to experiments with only a few animals. Here, we quantify the error made when the FS algorithm is applied to data of one-to-one experiments not having reached the final size. We conclude that given the chosen tests, the FS algorithm underestimates the reproduction ratio R0, is liberal when testing H0: R0 > or = 1 against H1: R0 < 1, is conservative when testing H0: R0 < or = 1 against H1: R0 > 1 and calculates the same probability as the TS algorithm when testing H0: R(0-control) = R(0-treatment) against H1: R(0-control) > R(0-treatment) We show how the power of the test depends on the duration of the experiments and on the number of replicates. The methods are illustrated by an application to porcine reproductive and respiratory syndrome virus (PRRSV).