Polarization-Sensitive Photoluminescence from Aligned Carbon Chains Terminated by Gold Clusters

We synthesize a thin film composed of long carbyne chains terminated by gold clusters and study its optical properties. The presence of gold particles stabilizes longer chains and leads to their alignment. We show that the gold clusters also act as a source of electron doping, thus, changing the intensity of photoluminescence from quadratic dependence on the pumping intensity without gold to linear with gold. We also observe that the excitation of the film at the gold plasmon frequency causes the blue shift of photoluminescence and estimate, on the basis of this effect, the minimum length of the carbyne chains. The high degree of alignment of the gold-terminated carbyne chains results in strongly anisotropic light absorption characterized by a distinctive cosine dependence on the angle between the carbyne molecule and polarization plane of the excitation. This paves the way for a new class of ultimately thin polarization sensitive emitters to be used in future integrated quantum photonics devices.

Observation of Zitterbewegung in photonic microcavities

We present and experimentally study the effects of the photonic spin-orbit coupling on the real space propagation of polariton wavepackets in planar semiconductor microcavities and polaritonic analogues of graphene. In particular, we demonstrate the appearance of an analogue Zitterbewegung effect, a term which translates as 'trembling motion' in English, which was originally proposed for relativistic Dirac electrons and consisted of the oscillations of the centre of mass of a wavepacket in the direction perpendicular to its propagation. For a planar microcavity, we observe regular Zitterbewegung oscillations whose amplitude and period depend on the wavevector of the polaritons. We then extend these results to a honeycomb lattice of coupled microcavity resonators. Compared to the planar cavity, such lattices are inherently more tuneable and versatile, allowing simulation of the Hamiltonians of a wide range of important physical systems. We observe an oscillation pattern related to the presence of the spin-split Dirac cones in the dispersion. In both cases, the experimentally observed oscillations are in good agreement with theoretical modelling and independently measured bandstructure parameters, providing strong evidence for the observation of Zitterbewegung.

What Are the Neurotoxins in Hemotoxic Snake Venoms?

Snake venoms as tools for hunting are primarily aimed at the most vital systems of the prey, especially the nervous and circulatory systems. In general, snakes of the Elapidae family produce neurotoxic venoms comprising of toxins targeting the nervous system, while snakes of the Viperidae family and most rear-fanged snakes produce hemotoxic venoms directed mainly on blood coagulation. However, it is not all so clear. Some bites by viperids results in neurotoxic signs and it is now known that hemotoxic venoms do contain neurotoxic components. For example, viperid phospholipases A₂ may manifest pre- or/and postsynaptic activity and be involved in pain and analgesia. There are other neurotoxins belonging to diverse families ranging from large multi-subunit proteins (e.g., C-type lectin-like proteins) to short peptide neurotoxins (e.g., waglerins and azemiopsin), which are found in hemotoxic venoms. Other neurotoxins from hemotoxic venoms include baptides, crotamine, cysteine-rich secretory proteins, Kunitz-type protease inhibitors, sarafotoxins and three-finger toxins. Some of these toxins exhibit postsynaptic activity, while others affect the functioning of voltage-dependent ion channels. This review represents the first attempt to systematize data on the neurotoxins from "non-neurotoxic" snake venom. The structural and functional characteristic of these neurotoxins affecting diverse targets in the nervous system are considered.

Anti-HIV Activity of Snake Venom Phospholipase A2s: Updates for New Enzymes and Different Virus Strains

Since the beginning of the HIV epidemic, lasting more than 30 years, the main goal of scientists was to develop effective methods for the prevention and treatment of HIV infection. Modern medicines have reduced the death rate from AIDS by 80%. However, they still have side effects and are very expensive, dictating the need to search for new drugs. Earlier, it was shown that phospholipases A2 (PLA2s) from bee and snake venoms block HIV replication, the effect being independent on catalytic PLA2 activity. However, the antiviral activity of human PLA2s against Lentiviruses depended on catalytic function and was mediated through the destruction of the viral membrane. To clarify the role of phospholipolytic activity in antiviral effects, we analyzed the anti-HIV activity of several snake PLA2s and found that the mechanisms of their antiviral activity were similar to that of mammalian PLA2. Our results indicate that snake PLA2s are capable of inhibiting syncytium formation between chronically HIV-infected cells and healthy CD4-positive cells and block HIV binding to cells. However, only dimeric PLA2s had pronounced virucidal and anti-HIV activity, which depended on their catalytic activity. The ability of snake PLA2s to inactivate the virus may provide an additional barrier to HIV infection. Thus, snake PLA2s might be considered as candidates for lead molecules in anti-HIV drug development.

Tipping the immunostimulatory and inhibitory DAMP balance to harness immunogenic cell death

Induction of tumor cell death is the therapeutic goal for most anticancer drugs. Yet, a mode of drug-induced cell death, known as immunogenic cell death (ICD), can propagate antitumoral immunity to augment therapeutic efficacy. Currently, the molecular hallmark of ICD features the release of damage-associated molecular patterns (DAMPs) by dying cancer cells. Here, we show that gemcitabine, a standard chemotherapy for various solid tumors, triggers hallmark immunostimualtory DAMP release (e.g., calreticulin, HSP70, and HMGB1); however, is unable to induce ICD. Mechanistic studies reveal gemcitabine concurrently triggers prostaglandin E2 release as an inhibitory DAMP to counterpoise the adjuvanticity of immunostimulatory DAMPs. Pharmacological blockade of prostaglandin E2 biosythesis favors CD103+ dendritic cell activation that primes a Tc1-polarized CD8+ T cell response to bolster tumor rejection. Herein, we postulate that an intricate balance between immunostimulatory and inhibitory DAMPs could determine the outcome of drug-induced ICD and pose COX-2/prostaglandin E2 blockade as a strategy to harness ICD.

JUSTIFICATION OF USING CROSSFIT TRAINING IN JUDO

Aim. The paper aims to justify the use of CrossFit training for improving special physical fitness of judokas. Materials and methods. Male judokas aged from 19 to 20 years (n = 23) who have an experience of at least 6 years were engaged in CrossFit training for 12 weeks. Their physical fitness was assessed using the following methods: SJFT, blood lactate concentration, load test (60 Ippon-Seoi-Nage). The results obtained were compared with the data of recent scientific studies of domestic and foreign experts. Results. Significant (p < 0.05) differences in the results of special judoka tests after 12 weeks of CrossFit training were revealed. A significant decrease in the recovery time of athletes was found. Blood lactate concentration in athletes significantly (p < 0.05) increased. Conclusion. The results of the study prove the effectiveness of regular CrossFit training sessions for judokas. The positive dynamics of the results of special tests indicates an increase in special physical fitness of athletes.

THE INCREASE OF PHYSICAL ACTIVITY IN PERSONS USING SPORTS GROUNDS FOR PHYSICAL TRAINING

Aim. The article deals with increasing the weekly physical activity (PA) of the persons of different age and gender attending sports grounds (SG). Materials and methods. 1726 residents of Glazov and Krasnoyarsk participated in the study. The age of the residents ranges from 18 to 78 years. The research lasted for 8 months (March – October 2018). The following methods have been used: a survey and a statistical recording of the number of residents visiting SG. To increase the physical activity of residents, volunteer activities were used, and information support for the effective use of street facilities was provided (training time, types of exercises, exercise load, etc.). The statistical analysis of the results was performed using the Student's t-test. Results. A significant (P < 0.01) increase of the number of residents who regularly (at least 3 times per week) visited SG was found. The most significant increase was found among the people aged 35–50 years and 50–65 years. Conclusion. The research shows that the work of volunteers and information materials about the effective use of street facilities contribute to a significant increase in the weekly PA of the residents of different age and gender.

Nano-Antennas Based on Silicon-Gold Nanostructures

We experimentally realize nano-antennas based on hybrid silicon-gold nanoparticles (NPs). The silicon particles covered by clusters of small metal NPs are fabricated from a liquid phase under the effect of the laser irradiation. The complex nanoclusters containing both Si and Au components provide the enhancement of the near-field intensity and the resonant light scattering associated with excitation of multipole resonances in NPs. A strong sensitivity of the resonant light absorption to the hybrid particle size and material parameters is experimentally documented and theoretically discussed. The results demonstrate a high potentiality of the hybrid NPs for the realization of functional optical devices and metasurfaces.

The Synthesis of Hybrid Gold-Silicon Nano Particles in a Liquid

We show that the laser ablation method can be efficiently employed for the synthesis of silicon nanoparticles (NP), which are characterized by a strong resonant optical response in the visible spectral range. A single layer composed of silicon NPs has been deposited from the colloidal solution generated by laser ablation. The formation of hybrid silicon-gold NPs as a result of the laser action on a mixed colloidal solution is observed. These hybrid NPs are characterized by broadening of the near-field photoluminescence spectra compared to pure silicon NPs. These results may be used for the realization of functional metasurfaces consisting of randomly distributed resonant NPs.

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine: Brussels, Belgium. 15-18 March 2016

[This corrects the article DOI: 10.1186/s13054-016-1208-6.].

Effects of snake venom polypeptides on central nervous system

The nervous system is a primary target for animal venoms as the impairment of its function results in the fast and efficient immobilization or death of a prey. There are numerous evidences about effects of crude snake venoms or isolated toxins on peripheral nervous system. However, the data on their interactions with the central nervous system (CNS) are not abundant, as the blood-brain barrier (BBB) impedes penetration of these compounds into brain. This updated review presents the data about interaction of snake venom polypeptides with CNS. Such data will be described according to three main modes of interactions: - Direct in vivo interaction of CNS with venom polypeptides either capable to penetrate BBB or injected into the brain. - In vitro interactions of cell or sub-cellular fractions of CNS with crude venoms or purified toxins. - Indirect effects of snake venoms or their components on functioning of CNS under different conditions. Although the venom components penetrating BBB are not numerous, they seem to be the most suitable candidates for the leads in drug design. The compounds with other modes of action are more abundant and better studied, but the lack of the data about their ability to penetrate BBB may substantially aggravate the potentials for their medical perspectives. Nevertheless, many such compounds are used for research of CNS in vitro. These investigations may give invaluable information for understanding the molecular basis of CNS diseases and thus lay the basis for targeted drug design. This aspect also will be outlined in the review.

cDNA cloning, structural, and functional analyses of venom phospholipases A₂ and a Kunitz-type protease inhibitor from steppe viper Vipera ursinii renardi

Snake venom phospholipases A₂ (PLA₂s) display a wide array of biological activities and are each characteristic to the venom. Here, we report on the cDNA cloning and characterization of PLA₂s from the steppe viper Vipera ursinii renardi venom glands. Among the five distinct PLA₂ cDNAs cloned and sequenced, the most common were the clones encoding a basic Ser-49 containing PLA₂ (Vur-S49). Other clones encoded either ammodytin analogs I1, I2d and I2a (designated as Vur-PL1, Vur-PL2 and Vur-PL3, respectively) or an ammodytoxin-like PLA₂ (Vurtoxin). Additionally, a novel Kunitz-type trypsin inhibitor for this venom species was cloned and sequenced. Comparison of these PLA₂ and Kunitz inhibitor sequences with those in the sequence data banks suggests that the viper V. u. renardi is closely related to Vipera ammodytes and Vipera aspis. Separation of V. u. renardi venom components by gel-filtration and ion-exchange chromatography showed the presence of many PLA₂ isoforms. Remarkably, the most abundant PLA₂ isolated was Vur-PL2 while Vur-S49 analog was in very low yield. There are great differences between the proportion of cDNA clones and that of the proteins isolated. Two Vur-PL2 isoforms (designated as Vur-PL2A and Vur-PL2B) indistinguishable by masses, peptide mass fingerprinting, N-terminal sequences and CD spectroscopy were purified from the pooled venom. However, when rechromatographed on cation-exchanger, Vur-PL2A showed only one peak corresponding to Vur-PL2B, suggesting the existence of conformers for Vur-PL2. Vur-PL2B was weakly cytotoxic to rat pheochromocytoma PC12 cells and showed both strong anticoagulant and anti-platelet activities. This is the first case of a strong anticoagulating ammodytin I analog in Vipera venom.

Seizures in cerebral arteriovenous malformations: type, clinical course, and medical management

SUMMARY

We investigated the type and early clinical course of seizure disorders in cerebral arteriovenous malformations (AVMs). Decisions on invasive treatment for AVMs depend on detailed knowledge of the natural course and prognosis of neurologic sequelae. Among 328 patients of a prospective cerebral AVM databank 92 (28%) presented with seizures unrelated to haemorrhage. Under a median observation time of 2.2 years (mean 3.8 years) the 92 patients received 454 follow-up examinations (median time interval 4.6 months). All patients were treated with anticonvulsant medication. During the observation period sixty (65%) patients received staged endovascular glue embolisation. The effect of staged embolisation on seizure recurrence was tested univariately by comparing patients undergoing embolisation versus those without endovascular treatment. At the time of enrolment in the database, elementary (motor or sensory) and partial complex seizures were described in twenty (22 %) and one (1%) patients, respectively. Generalized seizures without focal initiation were reported in sixty (65%) and with focal initiation in 11 (12%) patients. 57 (62%) cases had suffered a seizure as a first single event, ten (11%) had weekly, 17 (19%) monthly, and eight (9%) patients had seizures once per year. In the following clinical course, complete cessation of seizure activity was seen in 69 (75%). Ten (11%) patients continued to have seizures at a rate of once per year or less. 13 (14%) cases continued to have weekly to monthly events with only four (4%) of them showing (monthly) grand mal. An early beneficial effect of staged embolisation on seizure recurrence was not observed. Seizure disorders in cerebral AVMs show a benign early course, leaving few patients with insufficient seizure control. The differential longterm effect of invasive AVM treatment on seizure control should be subject to clinical trials.

NO-hemoglobin may be a light-sensitive source of nitric oxide both in solution and in red blood cells

Hemoglobin in solution and inside red blood cells forms a complex with nitric oxide exhibiting a specific EPR signal both at room and liquid nitrogen temperatures. In the present paper it was shown that the nitrosyl complex of hemoglobin (NO-Hb) is photochemically sensitive and hence may serve as a source of free NO under He-Cd laser irradiation (441 nm). It was found that at laser light radiant power of 3.9 mW, room temperature and in the presence of oxygen, 50% decrease of NO-Hb EPR signal occurred at doses of 54, 30, and 18 kJ/m2 for NO-hemoglobin solution, hemolysed and intact erythrocytes, respectively. The detection of free NO produced as a result of NO-Hb photolysis was performed by means of a spin trap, nitronyl nitroxyl radical NNR, which in the presence of NO is transformed into imino nitroxyl radical (INR) showing different EPR signal. In isolated hemoglobin solution, 20 mM INR was accumulated under irradiation with the maximal dose of 700 kJ/m2. In intact cells the HbFe(2+)-NO photolysis and NO release occur with essentially higher efficacy. To produce 100 mM INR, a dose of 290 kJ/m2 was needed in erythrocyte lysates and 100 kJ/m2 in intact red blood cell suspension. Measurements of absorption spectra showed that in all systems studied (NO-Hb in solution, intact erythrocytes and hemolysed erythrocytes) NO-Hb concentration decreased after irradiation by 14-22% with simultaneous formation of methemoglobin. These observations show that NO-Hb may serve as a store of nitric oxide from which free NO can be released by intensive illumination.

The use of induced sputum in the assessment of pulmonary involvement in Crohn's disease

OBJECTIVE

Our aim was to evaluate lung involvement in Crohn's disease (CRD) patients by induced sputum (IS). Extraintestinal manifestations are frequent in CRD, but lung involvement is rare. Induced sputum is a reliable noninvasive method of investigating the pathogenesis, pathophysiology, and treatment of lung disease.

METHODS

Twenty-four CRD patients and nine control subjects (all nonsmokers) without respiratory symptoms were tested. Sputum was induced by 20' inhalation of 3.5% saline using ultrasonic nebulizer. Samples were studied by differential counts of 200 cells on cytopreps stained by Giemsa. T-lymphocyte subset analyses were done by FACS using three monoclonal antibodies: CD3 = total T cells, CD4 = T helper cells, and CD8 = T suppressor-cytotoxic cells. CD4/CD8 >2.5 was considered abnormal.

RESULTS

Four patients did not produce sputum. Of the remaining 20 patients, seven had active CRD and 13 were in remission. They were divided into two groups: Group A patients had abnormal CD4/CD8 ratio of 6.7 +/- 2.5; Group B (seven patients) had normal CD4/CD8 ratio of 1.7 +/- 0.52 (p = 0.0001). The differential counts of IS samples were similar in both groups, but lymphocyte count was significantly higher in CRD patients than in the control group (13.2 +/- 11.2 vs 4.8 +/- 3.6, p = 0.036). There were no differences in spirometry, treatment, extent, or activity of CRD.

CONCLUSION

Using a simple noninvasive method, we found that among CRD patients without respiratory symptoms there was a high (65%) incidence of lung involvement.

Morbidity of intracranial hemorrhage in patients with cerebral arteriovenous malformation

BACKGROUND AND PURPOSE

Decisions on invasive arteriovenous malformation (AVM) treatment are currently based on natural-course risk estimates of AVM bleeding and assumptions on morbidity from cerebral hemorrhage in general. However, morbidity of AVM hemorrhage has rarely been reported. We sought to assess the morbidity of intracranial hemorrhage in patients with cerebral AVMs.

METHODS

From a prospective AVM database, 119 patients were analyzed: 115 had a hemorrhage as the diagnostic event, and 27 of them suffered a second hemorrhage during follow-up; an additional 4 patients had other diagnostic symptoms but bled during follow-up. The type (parenchymal, subarachnoid, intraventricular) and location of AVM hemorrhage were determined by CT/MR brain imaging. Disability and neurological impairment were assessed with the Barthel Index, the Rankin Scale, and the National Institutes of Health Stroke Scale, with a mean follow-up time of 16.2 months.

RESULTS

Of the 115 incident hemorrhages, 34 (30%) were subarachnoid, 27 (23%) parenchymal, 18 (16%) intraventricular, and 36 (31%) in combined locations. In 54 patients (47%; 95% confidence interval [CI], 38% to 56%) the incident hemorrhage resulted in no neurological deficit, and an additional 43 patients (37%; 95% CI, 28% to 46%) were independent in their daily activities (Rankin 1). Fifteen patients (13%; 95% CI, 7% to 19%) were moderately disabled (Rankin 2 or 3), and 3 (3%; 95% CI, 0% to 6%) were severely disabled (Rankin > or =4). Parenchymal hemorrhages were most likely to result in a neurological deficit (52%). Type and morbidity of hemorrhage during follow-up were similar to incident events. Twenty (74%) of 27 patients with both incident and follow-up hemorrhages were normal or independent (Rankin 0 or 1). None of the patients with a hemorrhage during follow-up died during the observation period.

CONCLUSIONS

Hemorrhage from cerebral AVMs appears to have a lower morbidity than currently assumed. This finding encourages a reevaluation of the risks and benefits of invasive AVM treatment.

[Therapy of cerebral arteriovenous malformations]

The rapid development of modern endovascular, microsurgical, and radiation therapies has considerably expanded the treatment options for encephalic arteriovenous malformations (AVMs). Surgery has the longest history. Single or staged intravascular procedures (embolizations) using fast-acting glues, sclerotic agents, and thrombogenic coils serve to reduce the size of AVM to that suitable for extirpation and may reduce the risk of surgery. Radiation ("gamma-knife") therapy, most frequently used in small, non-operable AVMs, is also viewed by some authors as an alternative or even superior tool in small, operable malformations. Partial embolization to reduce the mass-effect of space-occupying AVMs, to reverse diaschisis, and to treat AVM-related seizure disorders is being discussed and practiced. Given the in part competing or even controversial options, the selection of optimal treatment for AVM patients is becoming increasingly difficult. Current management is impeded by the paucity of information on the exact risks of invasive therapies and by insufficient criteria for identifying patients at risk of spontaneous bleeding during the natural course, including the seriousness of such hemorrhage.

Risk of spontaneous haemorrhage after diagnosis of cerebral arteriovenous malformation

BACKGROUND

A small proportion of strokes are caused by cerebral arteriovenous malformations (AVM). Treatment to prevent intracranial haemorrhage itself carries risks, and untreated AVM may in many cases have a good prognosis. We investigated the risk of subsequent symptomatic bleeding in the clinical course of AVM in patients with and without an initial haemorrhage.

METHODS

281 unselected, consecutive, prospectively enrolled patients with cerebral AVM were grouped according to their initial clinical presentation--142 presented with and 139 without haemorrhage. The frequency of AVM haemorrhages during the subsequent clinical course (before the start of endovascular, surgical, or radiation treatment) in the two groups was compared by means of Kaplan-Meier life-tables, log-rank test, and multivariate proportional-hazards regression models. Haemorrhage was defined as a clinically symptomatic event with signs of acute bleeding on computed tomography or magnetic resonance brain imaging.

FINDINGS

During mean follow-up of 8.5 months for the haemorrhage group and 11.9 months for the non-haemorrhage group, haemorrhages occurred in 18 (13%) of the former patients and in three (2%) of the latter (p=0.0002). The annual risk of haemorrhage was 17.8% and 2.2%, respectively. In the multivariate regression model, the adjusted hazard ratio for haemorrhage at initial presentation was 13.9 (95% CI 2.6-73.8; p=0.002). Deep venous drainage (hazard ratio 4.1 [1.2-14.9], p=0.029) and male sex (9.2 [2.1-41.3], p=0.004) were also significantly associated with subsequent haemorrhage, but no significant association was found for age or AVM size. The annual rate of spontaneous haemorrhage was 32.6% for men and 10.4% for women in the haemorrhage group compared with 3.3% for men and 1.3% for women in the non-haemorrhage group. Among patients with haemorrhage at initial presentation, the risk of haemorrhage fell from 32.9% in year 1 to 11.3% in subsequent years (34.2% to 31.0% in men; 31.1% to 5.5% in women).

INTERPRETATION

In AVM, patients initially presenting with haemorrhage have a higher risk of subsequent bleeding than those presenting with other symptoms. The risk is higher in men than in women.

The effect of arteriovenous malformations on the distribution of intracerebral arterial pressures

PURPOSE

To examine the distribution of arterial hypotension surrounding arteriovenous malformations (AVMs) using a standardized system of vascular zones.

METHODS

Mean arterial pressures were recorded during superselective cerebral angiography in 96 patients with AVMs (before they underwent liquid polymer embolization) with the use of a system of vascular zones: E = extracranial internal carotid or vertebral artery; I = intracranial internal carotid or basilar artery; T = transcranial Doppler insonation site (A1, P1, M1); H = halfway to feeder, perfusing normal tissue and shunt; and F = feeder at site of N-butyl cyanoacrylate injection. Distal arterial pressure was measured contralateral to the AVM in an additional 12 patients (zone Hc).

RESULTS

Zone pressures (mm Hg +/- SD) were E = 76 +/- 16, I = 69 +/- 15, T = 59 +/- 16, H = 47 +/- 13, and F = 39 +/- 15 mm Hg. Vessel/systemic ratios for the zones were E = 0.97 +/- 0.05, I = 0.86 +/- 0.08, T = 0.75 +/- 0.12, H = 0.61 +/- 0.13, and F = 0.50 +/- 0.18. Measurements were obtained in 29 patients in all five zones and all had similar mean values. Zone Hc pressure was 66 +/- 17 mm Hg and the ratio was 0.78 +/- 0.12, both greater than zone H values.

CONCLUSION

Using a standardized system of anatomic vascular zones, we found a progressive and significant decrease in intracerebral arterial pressure in patients with AVMs that proceeded from the circle of Willis to the nidus. Large areas of parenchyma sharing the same parent arterial supply may be subject to chronic hypotension.

'Steal' is an unestablished mechanism for the clinical presentation of cerebral arteriovenous malformations

BACKGROUND AND PURPOSE

Focal neurological deficits (FNDs) in patients with arteriovenous malformations (AVMs) have been widely attributed to the phenomenon of "cerebral steal." The incidence of focal deficits was investigated in a large prospective sample.

METHODS

Using data from patient history and examination, CT or MRI, and transcranial Doppler sonography, we studied 152 consecutive, prospective AVM patients for evidence of FNDs unrelated to a hemorrhagic event. Feeding mean arterial pressure was measured during superselective angiography.

RESULTS

Two (1.3%) of 152 patients met the criteria for a progressive FND. Nonprogressive FNDs were seen in 11 (7.2%) patients (stable in 4.6%, reversible in 2.6%). The median observation time period was 17 months (range, 1 to 60 months). There were no differences in transcranial Doppler mean velocities in feeding arteries in FND versus non-FND groups (118 +/- 44 versus 112 +/- 37 cm/s, P > .05) or pulsatility indexes (0.53 +/- 0.20 versus 0.55 +/- 0.15, P > .05). Feeding artery pressure was similar in FND (n = 10) and non-FND (n = 96) groups (39 +/- 16 versus 39 +/- 16 mm Hg at a systemic pressure of 82 +/- 18 versus 75 +/- 14 mm Hg, NS).

CONCLUSIONS

Nonhemorrhagic focal neurological syndromes in AVM patients are infrequent. Progressive deficits are especially rare. There was no relation between feeding artery pressure or flow velocities and FND. There does not appear to be sufficient evidence to assign steal as an operative pathophysiological mechanism in the vast majority of AVM patients.

Transcranial Doppler ultrasonography in cerebral arteriovenous malformations. Diagnostic sensitivity and association of flow velocity with spontaneous hemorrhage and focal neurological deficit

BACKGROUND AND PURPOSE

We sought to investigate (1) the sensitivity of transcranial Doppler ultrasonography (TCD) for diagnosis of cerebral arteriovenous malformations (AVMs) and (2) the association of feeding artery flow velocity profiles with spontaneous hemorrhage and focal neurological deficit in AVM patients.

METHODS

We examined 114 consecutive AVM patients prospectively by TCD; 22 non-AVM patients with acute cerebral hemorrhage and 52 normal subjects served as controls. To estimate the association of blood flow velocity patterns in feeding arteries with spontaneous hemorrhage and focal neurological deficit, the total group of AVM subjects was divided into patients with and without a history of bleeding and also into those with and without clinical signs of "steal" (focal deficit unrelated to hemorrhage).

RESULTS

Sensitivity for large and medium-sized AVMs was high (> 80%), whereas 62% of small AVMs were missed. TCD was also highly sensitive (80%) in a group of five AVM patients with acute hemorrhage. Flow velocity profiles were not related to spontaneous hemorrhage (mean velocity, 111 cm/s in patients with hemorrhage versus 114 cm/s in patients without hemorrhage; P = .65) or clinical signs of steal (mean velocity, 111 cm/s versus 113 cm/s in patients with and without steal, respectively; P = .89).

CONCLUSIONS

We concluded that (1) TCD is highly sensitive for large and medium-sized AVMs; (2) in acute cerebral hemorrhage TCD may help to differentiate AVM from non-AVM bleeds; (3) the predictive value of TCD findings for clinical sequelae of AVMs remains undetermined; and (4) the concept of hemodynamic steal in AVMs is not supported by TCD data.