Potential mosquito vector attraction to- and feeding preferences for pigs in Romanian backyard farms

Introduction

Mosquitoes either biologically or mechanically transmit various vector-borne pathogens affecting pigs. Mosquito species display a wide variety of host preference, as well as host attraction and behaviours. Mosquito species attraction rates to- and feeding rates on pigs or other potential hosts, as well as the seasonal abundance of the mosquito species affects their pathogen transmission potential.

Methods

We caught mosquitoes in experimental cages containing pigs situated in Romanian backyard farms. The host species of blood meals were identified with PCR and sequencing.

Results

High feeding preferences for pigs were observed in Aedes vexans (90%), Anopheles maculipennis (80%) and Culiseta annulata (72.7%). However, due to a high abundance in the traps, Culex pipiens/torrentium were responsible for 37.9% of all mosquito bites on pigs in the Romanian backyards, despite low feeding rates on pigs in the cages (18.6%). We also found that other predominantly ornithophilic mosquito species, as well as mosquitoes that are already carrying a blood meal from a different (mammalian) host, were attracted to backyard pigs or their enclosure.

Discussion

These results indicate that viraemic blood carrying, for instance, African swine fever virus, West-Nile virus or Japanese encephalitis virus could be introduced to these backyard pig farms and therefore cause an infection, either through subsequent feeding, via ingestion by the pig or by environmental contamination.

Serological Survey of Mosquito-Borne Arboviruses in Wild Birds from Important Migratory Hotspots in Romania

In the context of climate change, globalization, and enhanced human traveling, arboviruses continue to represent a threat to public health. West Nile and Usutu viruses are mosquito-borne viruses belonging to the Flaviviridae family (Flavivirus genus) and members of the Japanese encephalitis virus serocomplex. Included in the Togaviridae family (Alphavirus genus), the Sindbis virus is also vectored by mosquitoes. In the present study, we aimed to analyze the presence of antibodies concerning the abovementioned viruses in migratory and resident birds in the South-Eastern region of Romania, as avian hosts represent the main reservoir for human infection. Blood samples were collected from wild birds between May 2018 and October 2019 in nine locations from three counties. All the samples were serologically tested by ELISA and a serum neutralization test. Overall, a seroprevalence of 8.72% was registered for the West Nile virus, 2.71% for the Usutu virus, and 0% for the Sindbis virus. To our best knowledge, this is the first large-scale comprehensive study to assess the West Nile virus seropositivity in wild birds and the first serological confirmation of the Usutu virus in wild birds in Romania. Moreover, this is the only follow-up study reviewing the current seroprevalence of the Sindbis virus in Romania since 1975.

Age and impaired left atrial performance are associated with increased atrial fibrosis in patients with paroxysmal and persistent atrial fibrillation

Background

Atrial performance assessed by strain imaging is used as a surrogate for left atrial (LA) structural remodelling. Presence of low voltage zones (LVZs) detected by three-dimensional electroanatomical mapping in patients with atrial fibrillation (AF) denotes more expressed extrapulmonary substrate potentially leading to worse outcomes following pulmonary vein isolation (PVI) for the treatment of AF.

Purpose

The current study aims to investigate the association between strain imaging parameters from echocardiography and the presence and extent of LVZs derived from LA electroanatomical mapping in patients undergoing AF ablation.

Methods

Seventy-eight patients (58 males, 74%) aged 59±9.48 years undergoing PVI for paroxysmal (35 patients, 49%) or persistent AF were prospectively studied. Preprocedural echocardiography included LA strain imaging assessing global LA strain (LAS) and regional strain of the basolateral region (RSLB). During the procedure, LA electroanatomical mapping during paced atrial rhythm was performed in all patients obtaining a LA voltage map. All LA maps were analysed offline using a custom-made software calculating the zone of low bipolar voltage <0.5 mV (LVZ<0.5mV) and the total LA endocardial area excluding pulmonary veins antra. LVZ<0.5mv was expressed as an absolute value and as percentage of the whole LA area.

Results

Patients aged more than 65 years (N=21, 27%) demonstrated a larger area of LVZ<0.5mV: 25.5±17.8 cm2 vs. 9.4±10.6 cm2 in those younger than 65 years, P=0.001. This corresponded to a higher proportion of the LA area demonstrating LVZ<0.5mV in patients older than 65 years: 22.6±14.6% vs. 8.9±11.8% in those younger than 65 years, P<0.0001. Twenty-nine of 78 patients (37.1%) had preprocedural LAS<20% and 23 (29.5%) demonstrated RSLB of <21%. Patients with LAS <20% had a higher total LVZ<0.5mV: 20.3±16.6 cm2 vs. 9.8±12.1 cm2 in patients with LAS≥20% at baseline, P=0.004. This equaled to 17.7±15.6% vs. 9.5±11.9% of total LA area, respectively (P=0.011). Patients with RSLB<21% also demonstrated larger areas of LVZ<0.5mV in the LA: 21.6±17.9 cm2 vs. 10.39±11.83 cm2 in the patients with RSLB ≥21%, P=0.012. Expressed as a proportion of the whole LA area the difference remained significant: 18.8±17.1% vs. 9.9±11.6%, respectively P=0.01.

Conclusion

Older age and impaired LA performance assessed by LA strain imaging are associated with larger areas of LVZ<0.5mV possibly reflecting more expressed LA fibrotic changes in patients with paroxysmal and persistent AF. These findings might serve in the preprocedural selection of the patients undergoing catheter ablation of AF.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): Bulgarian Society of Cardiology

Seasonal dynamics of Phlebotomus neglectus (Diptera: Psychodidae) in cave microhabitats in Romania and the rediscovery of Sergentomyia minuta (Rondani, 1843) after 50 years

Background

In a countrywide study aiming to update the knowledge on diversity of sand fly species in Romania, a sand fly population was observed in an isolated system of cave microhabitats. The caves are located in the protected area of Canaraua Fetii, Dobrogea region, southeastern Romania. The highest sand fly diversity was recorded in this area between 1968 and 1970. This work presents a study conducted to estimate the seasonal variation of the sand fly species in correlation with the particular environmental factors of the isolated system of cave microhabitats.

Methods

Sand flies were collected between May and October 2020 from one trapping site of interest in Canaraua Fetii. The trapping site consisted of a cave entrance. CDC miniature light traps and sticky traps were used to collect insects from the exterior walls of the cave entrance. Species identification of collected sand flies was done using morphological keys. Statistical analysis of the trapping and climatic data was performed.

Results

From all collected sand flies, 99.7% (818/822) were Phlebotomus neglectus, 0.1% (1/822) Ph. balcanicus and 0.2% (2/822) Sergentomyia minuta. Sand fly activity was first observed on 2 July and last on 24 September. A monomodal abundance trend was present, with the peak activity between 16 and 17 July. The analysis of the climatic data showed correlations between the total number of captured sand flies and both average temperature and average relative humidity. The total number of collected specimens was statistically higher when CDC miniature light traps were used compared to sticky traps. The number of females on the sticky traps was significantly higher than the number of males on the same trap type. Compared with the sticky traps, significantly more males were collected by CDC miniature light traps. This is the first record of Se. minuta in Romania after 50 years of no records (despite the trapping effort of the last 5 years in the country). Also, Ph. sergenti, previously present in this location, was not found.

Conclusions

In the investigated natural habitat, the diversity of the sand fly species appears to have changed, with the predominance of Ph. neglectus instead of Ph. balcanicus and Se. minuta (recorded as the two predominant species in 1968–1970). A monomodal abundance trend was observed as in other regions of the country. The sand fly activity in this particular cave microhabitat appears to be longer than in other regions in Romania. Longer sand fly activity increases the zoonotic risk of various pathogenic species’ transmission, with an impact on public health, as sand flies are important insect vectors.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-04985-y.

General anaesthesia during radiofrequency ablation of atrial fibrillation is associated with improved procedural characteristics but with similar long-term outcomes: a single center study

Funding Acknowledgements

Type of funding sources: None.

Introduction

General anaesthesia (GA) or conscious sedation can be used during radiofrequency catheter ablation (RFCA) of atrial fibrillation (AF) based on physician’s and patient’s preference. Increasing number of centers include GA in their institutional protocols for RFCA of AF. 

Purpose

The current study aims to compare real-world data on procedural characteristics, complication rate and procedural outcomes in patients undergoing RFCA of AF under GA or sedation at a single center.

Methods

A total of 167 patients (116 males, age 57.53 ± 9.78 years) with paroxysmal or persistent AF undergoing RFCA were studied retrospectively. Patients underwent RFCA under GA (108 patients, Group 1) provided by the anaesthesia team at our institution or under conscious sedation (59 patients, Group 2) guided by the operator using bolus doses of midazolam and fentanyl. We compared procedural time, fluoroscopy time, dose-area product (DAP), number of lesions and cumulative RF time between the two groups. We also analysed the complication rates and the long-term outcome in the two groups. Results are presented as mean ± SD or median (25th – 75th percentile).

Results

  Groups 1 and 2 were comparable in terms of baseline clinical characteristics. Group 1 patients demonstrated significantly shorter procedural time as compared to Group 2: 149.52 ± 41.31 min vs. 208.23 ± 77.10 min, P < 0.0005. Fluoroscopy time was also shorter in Group 1 24 (20-31.75) min compared to 36 (22.5-46.5) min in Group 2, P < 0.0001. This corresponded to lower radiation dose expressed by DAP which was also significantly lower in Group 1 patients: 3230 (1660-6793.2) cGy/cm2 vs. 13880 (4215-21324) cGy/cm2 for Group 2, P < 0.0001. Administration of GA during the procedure was associated with lower number of RF applications: 52.49 ± 19.36 in Group 1 vs. 68.33 ± 30.74 in Group 2, P = 0.0001. This corresponded with the lower cumulative RF time noted in the patients from Group 1: 2499.2 ± 824.17 sec vs. 3220 ± 1357.26 sec in Group 2, P < 0.0001. Procedural complications occurred in 5 patients from Group 1 (4.6%) and in 8 patients (13.6%) in Group 2, P = 0.066. There was a single case of atrioesophageal fistula in a patient from Group 1. After a median follow-up of 20 (8-41) months 75% of the patients from both Group 1 and Group 2 were arrhythmia-free following 1.5 ± 0.68 procedures (P = 1.0). 

Conclusion

Performing RFCA of AF under GA is associated with shorter procedural time, lower radiation dose and with the need for less energy application. This does not result in significantly lower complication rates. Long-term procedural outcomes do not seem to be affected by the use of GA.

Evidence of West Nile Virus (WNV) Circulation in Wild Birds and WNV RNA Negativity in Mosquitoes of the Danube Delta Biosphere Reserve, Romania, 2016

West Nile virus (WNV) is a zoonotic flavivirus whose transmission cycle in nature includes wild birds as amplifying hosts and ornithophilic mosquito vectors. Bridge vectors can transmit WNV to mammal species potentially causing West Nile Fever. Wild bird migration is a mode of WNV introduction into new areas. The Danube Delta Biosphere Reserve (DDBR) is a major stopover of wild birds migrating between Europe and Africa. The aim of this study was to investigate the presence of WNV in the DDBR during the 2016 transmission season in wild birds and mosquitoes. Blood from 68 wild birds (nine different species) trapped at four different locations was analyzed by competitive ELISA and Virus Neutralization Test (VNT), revealing positive results in 8/68 (11.8%) of the wild birds by ELISA of which six samples (three from juvenile birds) were confirmed seropositive by VNT. Mosquitoes (n = 6523, 5 genera) were trapped with CDC Mini Light traps at two locations and in one location resting mosquitoes were caught. The presence of WNV RNA was tested in 134 pools by reverse transcription quantitative PCR (RT-qPCR). None of the pools was positive for WNV-specific RNA. Based on the obtained results, WNV was circulating in the DDBR during 2016.

Species diversity, host preference and arbovirus detection of Culicoides (Diptera: Ceratopogonidae) in south-eastern Serbia

BACKGROUND

Culicoides (Diptera: Ceratopogonidae) is a genus of small biting midges (also known as "no-see ums") that currently includes 1368 described species. They are proven or suspected vectors for important pathogens affecting animals such as bluetongue virus (BTV) and Schmallenberg virus (SBV). Currently little information is available on the species of Culicoides present in Serbia. Thus, the aim of this study was to examine species diversity, host preference and the presence of BTV and SBV RNA in Culicoides from the Stara Planina Nature Park in south-eastern Serbia.

RESULTS

In total 19,887 individual Culicoides were collected during three nights of trapping at two farm sites and pooled into six groups (Obsoletus group, Pulicaris group, "Others" group and further each group according to the blood-feeding status to freshly engorged and non-engorged). Species identification was done on subsamples of 592 individual Culicoides specimens by morphological and molecular methods (MALDI-TOF mass spectrometry and PCR/sequencing). At least 22 Culicoides species were detected. Four animal species (cow, sheep, goat and common blackbird) as well as humans were identified as hosts of Culicoides biting midges. The screening of 8291 Culicoides specimens in 99 pools for the presence of BTV and SBV RNA by reverse-transcription quantitative PCR were negative.

CONCLUSIONS

The biodiversity of Culicoides species in the natural reserve Stara Planina was high with at least 22 species present. The presence of C. imicola Kieffer was not recorded in this area. Culicoides showed opportunistic feeding behaviour as determined by host preference. The absence of SBV and BTV viral RNA correlates with the absence of clinical disease in the field during the time of sampling. These data are the direct outcome of a training programme within the Institutional Partnership Project "AMSAR: Arbovirus monitoring, research and surveillance-capacity building on mosquitoes and biting midges" funded by the programme SCOPES of the Swiss National Science Foundation.

First report of Borrelia burgdorferi sensu lato in two threatened carnivores: the marbled polecat, Vormela peregusna and the European mink, Mustela lutreola (Mammalia: Mustelidae)

Background

Lyme disease is a widespread cosmopolitan zoonosis caused by species belonging to the genus Borrelia. It is transmitted from animal reservoir hosts to humans through hard - ticks of genus Ixodes which are vectors of the disease.

Case presentation

Borrelia burgdorferi sensu lato infection was identified in a marbled polecat, Vormela peregusna, and two European minks, Mustela lutreola, from Romania, by PCR. RFLP revealed the presence of a single genospecies, Borrelia burgdorferi sensu stricto.

Conclusions

This is the first report of the Lyme disease spirochetes in the two mentioned hosts.

[Characteristics and prognosis of visual deficit caused by parasellar meningiomas]

Meningiomas are the most common slow growing tumors of the central nervous system which arise from the arachnoid cells. One certain group of them--tuberculum sellae (TS), cavernous sinus (CS), anterior clinoid (AC), and planum sphenoidale (PS) meningiomas, a group often called "parasellar", present with monocular or binocular visual deterioration, which is often unrecognized by patients until visual loss is severe and the tumor has reached a significant size.

AIM

To describes the type of visual deficit, severity of the symptoms and surgical treatment of tumors with the above mentioned localization.

MATERIAL AND METHODS

During the period 2003-2007 year, 93 patients (31 man, 62 women) diagnosed with meningiomas of the TS (31 cases), CS (16 cases), AC (21 cases), PS (17 cases), (see text) - 8, were diagnosed and operated on in the Department of Neurosurgery, University Hospital "St. Ivan Rilsky", Sofia, Bulgaria. Retrospective analysis was done.

RESULTS

Age at diagnosis ranged from 12 to 74 years, but the majority of cases were in the 5th and 6th decade of life. Localization of was: TS 33%, CS 17%, AC 24%, PS 18% and with more than one area affected in 8 %. The most common symptom was slowly progressing loss of monocular visual acuity (81% of cases). 68% of patients presented with already severely deteriorated vision (0.1-0). Neuro-ophthalmological examination (see text) the patients. Computed tomography and magnetic resonance imaging were the main diagnostic methods. "Gross" total resection was achieved in 62%, subtotal in 12%, partial in 26% of the cases. There was early improvement in 57% of the patients. Death due to cardio-respiratory insufficiency occurred in one case.

CONCLUSION

the progressive monocular visual deficit is often the first clinical symptom of the parasellar menigiomas. The early diagnosis is important for the success of surgery. Close collaboration between different specialists (ophthalmologists, neurologist and neurosurgeons) is essential for treatment of these tumors and prevention of the visual deterioration.

[Malignant progression of an anaplastic ganglioglioma into a glioblastoma multiforme--report on two cases and review of the literature]

INTRODUCTION

Ganglioglioma is an uncommon type of primary brain tumors. In most of the cases the tumor demonstrates benign clinical behaviour with long-term patients' survival. We present two cases ofhistologically confirmed anaplastic ganglioglioma in which malignant progression into a glioblastoma multiforme was seen. CASE 1: A 36 year-old female with known Turner syndrome and recent history of single generalized seizure. The contrast-enhanced magnetic resonance imaging (MRI) showed an infiltrating lesion of the left frontal lobe. The tumor was excised partially and the histological result was anaplastic ganglioglioma (World Health Organization - WHO. gr. III). No additional neurological deterioration occurred after the procedure. A postoperative radiotherapy was performed with total dose of 60 Gy. The patient was symptom-free for one year taking her anticonvulsant medications. Control neuroimaging studies (computer tomography - CT, and MRI) were made because of progressive headache, right limbs weakness and speech disturbances. A local tumor recurrence was found and the patient underwent second operative intervention with gross total tumor resection. The histological result was glioblastoma multiforme (WHO gr. IV glioma). The patient improved after the procedure. An involvement of the contralateral cerebral hemisphere was found on control CT-scan ten months later. The patient died after one month, 23 months after her initial diagnosis. CASE 2: A 17 year-old female with recent history of progressive headache and three generalized seizures preceded by involuntary movements of the right limbs. MRI data for large, heterointense tumor lesion in the left frontal lobe was found. A subtotal tumor removal was made. The histological result was anaplastic ganglioglioma (WHO gr. ILL). The patients' headache and right side hemiparesis improved after the intervention. She was seizure-free taking her anticonvulsant medications. Thirty-day-long fractionated radiotherapy was performed with total dose of 60 Gy. The patient remained symptom-free for thirteen months after initial surgical procedure. During the next month the patients, partial motor seizures relapsed. Progressive headache, diplopia, and visual acuity impairment also developed. The ventriculoperitoneal shunt was implanted with neuroimaging data for internal hydrocephalus development. The patients' headache and visual disturbances improved after the procedure. Data for additional local tumor growth was found on control CT-scan one month later. The patient underwent subtotal excision of the lesion and the actual histological result was glioblastoma multiforme. The patient deteriorated after the intervention according to her right limbs paresis and died one month and half later. 20 months after the initial diagnosis.

CONCLUSION

The gangliogliomas are uncommon in clinical practice. The tumor behaviour may vary between the patients in spite of the similar histological characteristics which indicates the possible presence of different tumor subtypes.

[Orbital lymphoma]

INTRODUCTION

Orbital lymphomas are neoplasms with increasing incidence in recent years in immunocompromised, as well as immunocompetent patients, which defines their social importance.

AIM

To describe and analyze the experience of the University hospital "'Sv. Ivan Rilski" with the treatment of this pathology for the period 1997-2008.

MATERIAL AND METHODS

Fourteen patients (8 females, 6 males - 13 primary orbital lymphomas, 1 systemic lymphoma). Mean age at diagnosis was 65.6 years (from 50 to 80 years). In 2/3 of the patients the lesion was localized in left eye, without a case with bilateral orbital involvement. Seven cases the diagnosis was made 6 months from the onset of symptoms, 5 cases - 1 year and 2 cases - more than one year. The most common clinical symptoms were exophthalmus (12 case), tumor or bulging mass of the eyelid - 8, diplopy - 6, decreased visual acuity - 5. Intraconal localization of the tumor was in 6 cases, extraconal - 2. intra-extraconal - 6. The diagnosis was made by neuro-ophthalmologist and precised with the aid of CT and MRI. All the patients were operated on with the following approaches - fronto-orbital - 9 cases, lateral - 3, anterior orbitotomy (without bone resection) - 2 cases. In six cases "'gross total" resection was achieved, in the rest of the cases the resection was partial. On histological examination, a high grade lymphoma was established in 2 cases with primary orbital lymphoma and one case with systemic lymphoma. All other cases were diagnosed as low-grade B-call small lymphocytic non-Hodgkin's lymphoma. Long-term survival (over 5 years) was observed in 4 cases with primary lymphoma, whereas the patient with systemic form of the disease died 10 months after the operation.

Virtual simulation of neuroendoscopic procedures: early clinical experience with ventricular lesions

BACKGROUND

Virtual endoscopy (VE) is a new and promising imaging technology. Applied to neuroendoscopy it allows preoperative simulation of a procedure and evaluation of the individual intraventricular anatomy in selected cases. Along with neuronavigation and real time intraoperative imaging, VE is expected to improve the safety and efficacy of neuroendoscopic procedures.

PATIENTS AND METHODS

Between April 2003 and February 2004 VE simulation was performed in 13 randomly selected patients subjected to endoscopic procedures. Pathological entities included 4 cases with aqueduct stenosis, 4 with suprasellar arachnoid cysts, 2 tumors of the posterior third ventricle, 1 colloid cyst, 1 hyperplasia of the choroid plexus and 1 case with multiloculated hydrocephalus due to intraventricular septations. In 8 patients VE was accomplished preoperatively, in another 5 it was done after the operation, using data sets from neuronavigation imaging planning in 4 patients, and in one case using postoperative imaging studies. T (1)-weighted 3D image sets were acquired on a 1.5 T GE Genesis SIGNA MR scanner and VE reconstruction was performed using the General Electric Navigator software. The VE images were compared with the real images obtained during the endoscopic procedures and evaluated for their impact on the planning of the operative approach.

RESULTS

VE implementation succeeded in all 13 patients. Major neuroanatomic reference structures were easily recognizable in all cases. Membranous structures such as the thinned floor of the third ventricle or cyst walls were identifiable in only 46 % of the cases. In 6 cases (46 %) VE showed anatomical variants and details relevant for the endoscopic procedure that were not identified on conventional MR images.

CONCLUSIONS

VE has proved to be an important adjunct to the preoperative planning of neuroendoscopic procedures and its routine application is suggested.

Continuous-wave lasing of a stoichiometric Yb laser material: KYb(WO4)2

For the first time to the authors' knowledge, continuous-wave laser emission of the stoichiometric crystal KYb(WO4)2 was achieved at 1068 nm. The 125-microm-thin sample was directly water cooled and pumped at 1025 nm by a Ti:sapphire laser. The maximum output power at room temperature was 20 mW.

The complexity of linkage analysis with neural networks

As the focus of genome-wide scans for disease loci have shifted from simple Mendelian traits to genetically complex traits, researchers have begun to consider new alternative ways to detect linkage that will consider more than the marginal effects of a single disease locus at a time. One interesting new method is to train a neural network on a genome-wide data set in order to search for the best non-linear relationship between identity-by-descent sharing among affected siblings at markers and their disease status. We investigate here the repeatability of the neural network results from run to run, and show that the results obtained by multiple runs of the neural network method may differ quite a bit. This is most likely due to the fact that training a neural network involves minimizing an error function with a multitude of local minima.

Surgical management of intraosseous skull base tumors with aid of Operating Arm System

Invasion of bone and critical neurovascular structures often impedes complete resection of intraosseous skull base neoplasms, and these lesions tend to recur unless all infiltrated bone is removed. Evolving experience with image guidance over the past few years indicates the potential value of neuronavigation in skull base lesions diffusely infiltrating or fixed to bone structures. We report our early experience with the Radionics Operating Arm System (OAS), specifically emphasizing its utility as an adjunct in the treatment of intraosseous skull base tumors, mainly meningiomas. In April 1995 the OAS was introduced into clinical use at the neurosurgical university clinic in Münster, Germany. Since then, the system's utility has been explored in 10 patients out of the total neuronavigation series presenting with intraosseous skull base tumors (nine females and one male, mean age 47 years; nine meningiomas, one chordoma). For navigational planning, both 3-mm computed tomography scans and a set of 3-mm fat-suppression magnetic resonance images were chosen. At least four adhesive skin markers were used for system calibration. The system was technically usable in all cases in this small series. Because of the relative immobility of the bone structures and/or the tumor, no significant deviation from the preoperative registration accuracy was noted at the end of the procedures. The main advantages were easier localization and resection of infiltrated bone, which is often not grossly identifiable, even under the microscope. Our preliminary experience with the OAS suggests that image guidance is helpful in this type of lesion, providing better anatomical orientation during surgery and delineating tumor margins and their relation to critical neurovascular structures. The problem of a possible intracranial tumor and brain shift can be neglected in these lesions. The system facilitates resection by volumetric contour information, allowing more aggressive and complete resection.

Analysis of bipolar disorder using affected relatives

We have analyzed the GAW10 data from several studies of bipolar affective disorder (BPAD) using the software packages SimIBD and SIMWALK2. SimIBD implements a simulation-based affected-pedigree-member (APM) statistic, called SimAPM, as well as an APM-like statistic, also called SimIBD, that measures identical-by-descent (IBD) sharing. SIMWALK2 uses Markov chain Monte Carlo techniques to compute several IBD-based statistics on the degree of marker-allele clustering among all affected relatives. We have found no strong evidence of linkage to either chromosome 5 or 18. However, we did find that several markers showed p-values less than 0.01 and may deserve further study.

A comparison of two algorithms, MultiMap and gene mapping system, for automated construction of genetic linkage maps

Using the GAW11 Problem 2 data set, we compared the performance of two automated map construction algorithms, MultiMap and GMS (Gene Mapping System). The MultiMap algorithm iteratively adds markers in a stepwise manner to the map, while the GMS algorithm seeks to find the best order of the whole set of markers by selective permutations of logically formed subgroups of the markers. While it is difficult to compare these two rather different algorithms, we found that, on these data, GMS performed better than MultiMap, placing more markers in their true order on average, with little order ambiguity. In addition, as the number of markers increased, GMS was less computationally demanding than MultiMap. However, it MultiMap placed a marker, it was almost always in the correct order. In contrast, GMS often placed a group of markers on the wrong end of the map; such incorrect placements occur when the evidence for placement on one end or the other is not strong. Thus, there is room for further algorithmic developments that combine the strengths of both the MultiMap and GMS approaches.

Lipofuscin product accumulation, insufficient antioxidant defence in erythrocytes and plasma and enhanced susceptibility to oxidative haemolysis after thermal trauma

The mechanism of increased susceptibility of red blood cells to oxidative haemolysis in the early post-burn period remains unclear. In this study it was revealed that the accumulation of lipofuscin products in red blood cells was accompanied by the elevation of oxidative haemolysis on the 24th hour after thermal trauma of rats (full thickness skin, on 20% of TBSA). Enhanced thiobarbituric acid reactive substrates (TBARS) and lowered levels of antioxidants such as alpha-tocopherol, ceruloplasmin and albumin were found in plasma. The activity of superoxide dismutase (SOD) and the concentration of alpha-tocopherol and reduced glutathione (GSH) in erythrocytes were also diminished. The results from this study suggest that plasma and intracellular antioxidant deficiency can potentiate oxidative membrane damage. There was a positive correlation (r = 0.72) between increased levels of lipofuscin products and oxidative haemolysis of red blood cells. The enhanced susceptibility of erythrocytes to oxidative haemolysis may be considered as an indirect but sensitive indicator of the impaired antioxidant defence of these blood cells following thermal skin injury. The decreased resistance of red blood cell to oxidative haemolysis under the conditions of reduced antioxidant defence of erythrocytes and blood plasma suggests that adequate antioxidant therapy could prevent all these complications after thermal skin injury.

Reversible focal ischemia model in the rat: correlation of somatosensory evoked potentials and cortical neuronal injury

Somatosensory evoked potentials (SEPs) are valuable in experimental stroke studies, but only a few reports have dealt with small rodent models. Our experiments aimed to reproduce SEP monitoring during reversible middle cerebral artery occlusion (MCAo) in a surgical model of open craniotomy and vessel manipulations in the rat. The changes of median nerve SEPs were correlated to the degree of local cortical neuronal injury in the forelimb area. Based on a pilot group (n = 11) both parameters were examined at 2 h after reperfusion in a subsequent study with increase of MCAo time from 1 (n = 7) to 2 h (n = 7); 5 rats were sham operated. A significantly delayed and incomplete recovery of SEPs, expressed as a percentage of the mean preocclusion values was observed with 2 h compared to 1 h MCAo (20.8% versus 6.0% change in the latency and 59.5% versus 2.2% in the amplitude of the primary cortical response). The functional outcome was found to correlate consistently with the degree of neuronal damage in 1 and 2 h reversible MCAo (2.5% versus 79.2% severely damaged neuronal types III and IV). Our findings suggest, that 2 h MCAo followed by 2 h reperfusion produces a submaximal neuronal injury and partial electrical recovery in the periphery of the occluded vascular territory and could be therefore used as a reliable model for assessment of cerebroprotective drug efficacy.

Answering the connectionist challenge: a symbolic model of learning the past tenses of English verbs

Supporters of eliminative connectionism have argued for a pattern association-based explanation of language learning and language processing. They deny that explicit rules and symbolic representations play any role in language processing and cognition in general. Their argument is based to a large extent on two artificial neural network (ANN) models that are claimed to be able to learn the past tenses of English verbs (Rumelhart & McClelland, 1986, Parallel distributed processing, Vol. 2, Cambridge, MA: MIT Press; MacWhinney & Leinbach, 1991, Cognition, 40, 121-157). In this article we critically review Rumelhart and McClelland's as well as MacWhinney and Leinbach's ANN models and conclude that they do not succeed in the assigned task of learning the past tenses of English verbs. In order to answer their challenge to the symbolic processing approach, we present our symbolic pattern associator (SPA)-a general-purpose pattern associator that can learn to associate arbitrary discrete patterns. We carried out several experiments with the SPA using the same set of verbs that was used in MacWhinney and Leinbach's simulation with more realistic training and testing procedures. The SPA outperformed the connectionist models by a wide margin in the accuracy of learning, and successful inductive generalizations to unseen verbs. Our SPA has very natural and psychologically realistic explanations to many psychological effects such as U-shaped learning curve, and is much closer to human subjects in predicting past tense of the pseudo-verbs. In contrast to ANNs, whose internal representations are entirely opaque, the SPA can represent the acquired knowledge in the form of production rules that allow for further higher-level processing and integration, resulting in linguistically realistic associative templates for irregular verbs and production rules for regular verbs. In the light of these findings, we conclude that eliminative connectionists' vision of cognition as simple pattern association and pattern recognition without symbolic representation is inadequate. Pattern association as such does not imply rule-less or cue-based models of language acquisition or of human learning in general.

Lack of effect of PN 200-110 on neuronal injury and neurological outcome in middle cerebral artery-occluded rats

We evaluated the influence of a continuous intravenous infusion of 0.24 mg/kg PN 200-110 started 20 minutes before the induction of ischemia and continued for 2 hours on infarct size, histopathology, and neurological outcome in middle cerebral artery-occluded rats treated with PN 200-110 (n = 8), placebo (n = 7), or saline (n = 8). Neurological examination was performed 24 hours after occlusion. We quantified infarct size by 2,3,5-triphenyl-tetrazolium chloride, hematoxylin and eosin, and Nissl staining and by computerized analysis of tracings of the infarcted areas and evaluated neuronal injury at the infarct periphery. The different types of ischemic cell damage were quantified by direct visual counting. We found no differences among saline-, placebo-, and PN 200-110-treated rats regarding infarct size, amount of neuronal alteration, and neurological outcome. Our results indicate the lack of a significant protective effect of this drug in experimental focal ischemia.

Effect of nimodipine in treatment of experimental focal cerebral ischaemia

Despite the voluminous current literature the potential of nimodipine to modify the outcome in experimental cerebral ischaemia remains a controversial matter. The authors have evaluated in controlled double blind experiments the influence of a continuous i.v. infusion of the drug (1 microgram kg-1 min-1) upon infarct size, histopathology and neurological outcome in rats with permanent middle cerebral artery (MCA) occlusion. The infusion was started 20 min before induction of ischaemia and continued 4 hours thereafter. The nimodipine treated animals were subdivided into hypotensive (MABP lower than 85 mmHg for more than 5 min after arterial occlusion) and normotensive groups. Infarction size, documented by TTC, H&E and Nissl staining was significantly smaller (p less than 0.001) in nimodipine normotonic rats than the lesions in placebo and saline treated rats, as well compared with hypotonic nimodipine animals (largest infarction). These differences were found to be entirely at the expense of the cortical (frontoparietal) component of the lesion, suggesting 'penumbra' action of the drug. Moreover, nimodipine normotonic rats displayed lower cortical neuronal injury in the periinfarct zone. These findings were corroborated by corresponding better neurological scores. Our results indicate that nimodipine is effective in reducing focal cerebral ischaemia, provided the MABP is maintained higher than 85 mmHg.

The Dandy-Walker syndrome: diagnostic and surgical considerations

Thirteen cases of the Dandy-Walker syndrome were seen over a period of 12 years. In this study their preoperative evaluation, surgical treatment and outcome is reviewed. The incidence of hydrocephalus in the series was 77%. Eight of the patients had associated central nervous system anomalies, and the need to identify these abnormalities is stressed. Because the two conditions require different surgical management, during the diagnostic work-up it is crucial to differentiate between the Dandy-Walker syndrome and extra axial cerebrospinal fluid (CSF) filled cysts, and to establish the patency of the aqueduct. The reliability of different diagnostic methods is discussed and the value of metrizamide computed tomographic ventriculography is emphasized. Unsatisfactory results following membrane excision in early cases, and observations of CSF dynamic disturbances confirm the futility of the direct approach for the management of the Dandy-Walker syndrome. The aqueduct was invariably patent and allowed either primary cyst or ventricular shunting, although simultaneous double shunting using a 'Y' connector may need to be carried out later. The mortality rate for the series was 18%. At follow-up 54.5% of the children were judged to have normal IQs.

Intracranial ependymomas in children

During a 20-year period (1964-1983), the authors managed 60 children with intracranial ependymomas. In 37 patients the tumors were located in the posterior cranial fossa, and in the remaining 23 they were supratentorial. The histological examination in 26 children revealed ependymoblastomas. The average duration of the clinical evolution was 4 months and 5 days in the supratentorial neoplasms and 3 months and 6 days in the subtentorial. Besides the intracranial hypertension, present in about 80% of the patients, specific localizing signs were seen in 70% of the children with subtentorial and in 40% of those with supratentorial tumors. Because of the growth pattern in posterior fossa ependymomas and despite the prevalence of histologically benign neoplasms, radical resection was accomplished in only 21.6% of the cases, as compared with 30.4% in supratentorial tumors. The postoperative mortality remains high: 29.7% in subtentorial tumors and 17.4% in supratentorial. The 1-year survival rate in subtentorial neoplasms was 70.3%, the 3-year survival 29.7%, and the 5-year survival 16.2%. The corresponding figures for supratentorial ependymomas more favorable: 82.6%, 43.5%, and 26.1%, respectively. The most important factors for improving the outcome at the present time appear to be as radical a resection as possible, supplemented with postoperative radiotherapy and chemotherapy.

An evaluation of the surgical treatment of intracranial arachnoid cysts in children

In the period 1976-1987, the number of intracranial arachnoid cysts treated at our institute was 60: sylvian, 29; midline supratentorial, 13; subtentorial, 18. The diagnosis was mainly made by means of the results of a combination of CT, dynamic cisternography, and ventriculography. Based on an analysis of the preoperative investigations and operative results, an attempt was made to determine the appropriate treatment more precisely in cysts at different locations. The direct microsurgical approach with membrane excision was mainly used in combination with a preliminary VA shunt to treat hydrocephalus. The direct approach was supplemented with secondary cavity shunting in 5 cases. In more than half of the patients we used membrane excision alone (mainly children with sylvian cysts). In suprasellar cysts we consider the subfrontal approach to be more appropriate than the transventricular one. We restricted the use of primary cyst shunting as an alternative treatment to only 3 infants, with huge cysts. The follow-up reveals that 82.7% of the cases were favorable affected to varying degrees.

Long-term follow-up after surgical treatment of cerebellar astrocytomas in 100 children

A retrospective study was performed in 100 children, who were operated on between 1954 and 1984 for cerebellar astrocytoma. Twenty-nine patients died during the 1st month after the operation. Of the patients who survived, 24 lived up to 5 years, 17 up to 10 years, and 30 lived 20 or more years. In 22 cases, tumor recurrence was the reason for reoperation. Radiation therapy was used in 25 cases with histological malignancy and/or after partial removal of the tumor. The analysis in 6 cases with brainstem involvement allowed us to conclude that in such cases the prognosis is poor with regard to survival. Although total removal of cerebral astrocytomas appears to be the most effective form of treatment, we are of the opinion that even subtotal excision may be compatible with long-term survival. This suggests that many of these tumors may show benign biological behavior.

[Hydroanencephaly]

The clinical and X-ray findings in 9 infants with total and in one infant with unilateral forms of hydroanencephaly are discussed. This rare anomaly of the central nervous system is interesting from several standpoints: study of the etiopathogenic mechanisms responsible for atrophy of the hemispheres; study of different clinical phenomena in the absence of the cerebral hemispheres; study of c.s.f. changes in the absence of cerebral parenchyma; differential diagnosis with other pathological conditions, with extreme degree of hydrocephalus in the first place, which is very important for the therapeutic approach and prognosis. Attention is focus ed on the specific features of the clinical course, computer tomography (CT), angiographic and PEG values in hydroanencephaly. The etiopathogenesis of this severe pathological condition of the central nervous system is discussed on the basis of data in the literature.