Combined Analysis of Neutrino and Antineutrino Oscillations at T2K

T2K reports its first results in the search for CP violation in neutrino oscillations using appearance and disappearance channels for neutrino- and antineutrino-mode beams. The data include all runs from January 2010 to May 2016 and comprise 7.482×10^{20} protons on target in neutrino mode, which yielded in the far detector 32 e-like and 135  μ-like events, and 7.471×10^{20} protons on target in antineutrino mode, which yielded 4 e-like and 66  μ-like events. Reactor measurements of sin^{2}2θ_{13} have been used as an additional constraint. The one-dimensional confidence interval at 90% for the phase δ_{CP} spans the range (-3.13, -0.39) for normal mass ordering. The CP conservation hypothesis (δ_{CP}=0, π) is excluded at 90% C.L.

Measurement of Coherent π^{+} Production in Low Energy Neutrino-Carbon Scattering

We report the first measurement of the flux-averaged cross section for charged current coherent π^{+} production on carbon for neutrino energies less than 1.5 GeV, and with a restriction on the final state phase space volume in the T2K near detector, ND280. Comparisons are made with predictions from the Rein-Sehgal coherent production model and the model by Alvarez-Ruso et al., the latter representing the first implementation of an instance of the new class of microscopic coherent models in a neutrino interaction Monte Carlo event generator. We observe a clear event excess above background, disagreeing with the null results reported by K2K and SciBooNE in a similar neutrino energy region. The measured flux-averaged cross sections are below those predicted by both the Rein-Sehgal and Alvarez-Ruso et al.

Measurement of Muon Antineutrino Oscillations with an Accelerator-Produced Off-Axis Beam

T2K reports its first measurements of the parameters governing the disappearance of ν[over ¯]_{μ} in an off-axis beam due to flavor change induced by neutrino oscillations. The quasimonochromatic ν[over ¯]_{μ} beam, produced with a peak energy of 0.6 GeV at J-PARC, is observed at the far detector Super-Kamiokande, 295 km away, where the ν[over ¯]_{μ} survival probability is expected to be minimal. Using a data set corresponding to 4.01×10^{20} protons on target, 34 fully contained μ-like events were observed. The best-fit oscillation parameters are sin^{2}(θ[over ¯]_{23})=0.45 and |Δm[over ¯]_{32}^{2}|=2.51×10^{-3}  eV^{2} with 68% confidence intervals of 0.38-0.64 and 2.26-2.80×10^{-3}  eV^{2}, respectively. These results are in agreement with existing antineutrino parameter measurements and also with the ν_{μ} disappearance parameters measured by T2K.

Predictors of Stroke, Myocardial Infarction or Death within 30 Days of Carotid Artery Stenting: Results from the International Carotid Stenting Study

OBJECTIVES

Stroke, myocardial infarction (MI), and death are complications of carotid artery stenting (CAS). The effect of baseline patient demographic factors, processes of care, and technical factors during CAS on the risk of stroke, MI, or death within 30 days of CAS in the International Carotid Stenting Study (ICSS) were investigated.

METHODS

In ICSS, suitable patients with recently symptomatic carotid stenosis > 50% were randomly allocated to CAS or endarterectomy. Factors influencing the risk of stroke, MI, or death within 30 days of CAS were examined in a regression model for the 828 patients randomized to CAS in whom the procedure was initiated.

RESULTS

Of the patients, 7.4% suffered stroke, MI, or death within 30 days of CAS. Independent predictors of risk were age (risk ratio [RR] 1.17 per 5 years of age, 95% CI 1.01-1.37), a right-sided procedure (RR 0.54, 95% CI 0.32-0.91), aspirin and clopidogrel in combination prior to CAS (compared with any other antiplatelet regimen, RR 0.59, 95% CI 0.36-0.98), smoking status, and the severity of index event. In patients in whom a stent was deployed, use of an open-cell stent conferred higher risk than use of a closed-cell stent (RR 1.92, 95% CI 1.11-3.33). Cerebral protection device (CPD) use did not modify the risk.

CONCLUSIONS

Selection of patients for CAS should take into account symptoms, age, and side of the procedure. The results favour the use of closed-cell stents. CPDs in ICSS did not protect against stroke.

Measurement of the inclusive electron neutrino charged current cross section on carbon with the T2K near detector

The T2K off-axis near detector ND280 is used to make the first differential cross-section measurements of electron neutrino charged current interactions at energies ∼1  GeV as a function of electron momentum, electron scattering angle, and four-momentum transfer of the interaction. The total flux-averaged ν(e) charged current cross section on carbon is measured to be ⟨σ⟩(ϕ)=1.11±0.10(stat)±0.18(syst)×10⁻³⁸ cm²/nucleon. The differential and total cross-section measurements agree with the predictions of two leading neutrino interaction generators, NEUT and GENIE. The NEUT prediction is 1.23×10⁻³⁸ cm²/nucleon and the GENIE prediction is 1.08×10⁻³⁸ cm²/nucleon. The total ν(e) charged current cross-section result is also in agreement with data from the Gargamelle experiment.

Precise measurement of the neutrino mixing parameter θ23 from muon neutrino disappearance in an off-axis beam

New data from the T2K neutrino oscillation experiment produce the most precise measurement of the neutrino mixing parameter θ23. Using an off-axis neutrino beam with a peak energy of 0.6 GeV and a data set corresponding to 6.57×10(20) protons on target, T2K has fit the energy-dependent νμ oscillation probability to determine oscillation parameters. The 68% confidence limit on sin(2)(θ23) is 0.514(-0.056)(+0.055) (0.511±0.055), assuming normal (inverted) mass hierarchy. The best-fit mass-squared splitting for normal hierarchy is Δm32(2)=(2.51±0.10)×10(-3)  eV(2)/c(4) (inverted hierarchy: Δm13(2)=(2.48±0.10)×10(-3)  eV(2)/c(4)). Adding a model of multinucleon interactions that affect neutrino energy reconstruction is found to produce only small biases in neutrino oscillation parameter extraction at current levels of statistical uncertainty.

Observation of electron neutrino appearance in a muon neutrino beam

The T2K experiment has observed electron neutrino appearance in a muon neutrino beam produced 295 km from the Super-Kamiokande detector with a peak energy of 0.6 GeV. A total of 28 electron neutrino events were detected with an energy distribution consistent with an appearance signal, corresponding to a significance of 7.3σ when compared to 4.92±0.55 expected background events. In the Pontecorvo-Maki-Nakagawa-Sakata mixing model, the electron neutrino appearance signal depends on several parameters including three mixing angles θ12, θ23, θ13, a mass difference Δm(32)(2) and a CP violating phase δ(CP). In this neutrino oscillation scenario, assuming |Δm(32)(2)|=2.4×10(-3)  eV(2), sin(2)θ(23)=0.5, and Δm322>0 (Δm(32)(2)<0), a best-fit value of sin(2)2θ(13)=0.140(-0.032)(+0.038) (0.170(-0.037)(+0.045)) is obtained at δ(CP)=0. When combining the result with the current best knowledge of oscillation parameters including the world average value of θ(13) from reactor experiments, some values of δ(CP) are disfavored at the 90% C.L.

Measurement of neutrino oscillation parameters from muon neutrino disappearance with an off-axis beam

The T2K Collaboration reports a precision measurement of muon neutrino disappearance with an off-axis neutrino beam with a peak energy of 0.6 GeV. Near detector measurements are used to constrain the neutrino flux and cross section parameters. The Super-Kamiokande far detector, which is 295 km downstream of the neutrino production target, collected data corresponding to 3.01×10(20) protons on target. In the absence of neutrino oscillations, 205±17 (syst) events are expected to be detected while only 58 muon neutrino event candidates are observed. A fit to the neutrino rate and energy spectrum, assuming three neutrino flavors and normal mass hierarchy yields a best-fit mixing angle sin2(θ23)=0.514±0.082 and mass splitting |Δm(32)(2)|=2.44(-0.15)(+0.17)×10(-3) eV2/c4. Our result corresponds to the maximal oscillation disappearance probability.

Co-producing social inclusion: the structure/agency conundrum

There is a raft of policy guidelines indicating that mental health nurses should be increasing the social inclusion of mental health service users. Despite this there is no universally accepted definition of social inclusion and there is a dearth of empirical evidence on the successful outcome of increasing inclusion for mental health service users. Recognizing the lack of clarity surrounding the concept we have a produced a social inclusion framework to assist mental health professionals and service users to co-produce social inclusive outcomes. Although we agree that social inclusion can be a positive aspect of recovery, we question the extent to which mental health nurses and service users in co-production can overcome the social, economic and political structures that have created the social exclusion in the first place. An understanding and appreciation of the structure/agency conundrum is required if mental health nurses are to engage with service users in an attempt to co-produce socially inclusive outcomes.

Retained and fractured microcatheter: a cause of transient ischaemic attacks: endovascular management using carotid stents

A retained microcatheter is a rare complication of endovascular treatment of cerebral aneurysms. We describe such a case that was complicated by delayed microcatheter fracture within the internal carotid artery and subsequent thrombo-embolism resulting in transient ischaemic attacks. We also describe endovascular management of this complication through the use of several carotid stents.

Evaluation of the Chief Nursing Officer's Review of mental health nursing in England: findings from case studies in mental health trusts

This study is an evaluation of the implementation of the Chief Nursing Officer for England's Review of mental health nursing in mental health trusts (MHTs). The authors employed instrumental case studies in six MHTs. The results showed evidence of acceptance of the Review and some evidence of subsequent actions to implement the Review recommendations, but these were not widespread. A lack of an evidence-based implementation plan hampered the implementation as did an apparent lack of strategic nursing leadership in many MHTs. In conclusion, the vision for mental health nursing reported in the Chief Nursing Officer Review prompted various changes, directly and indirectly, among mental health nurses and the development of areas of good practice in education, practice and leadership. The positive changes evident in some areas may become widespread by a systematic policy implementation plan from the centre, supported by local leadership in practice.

The use of intraoperative monitoring and treatment of symptomatic microemboli in carotid artery stenting: case report and discussion

Carotid artery stenting is a recently introduced treatment in symptomatic atherosclerotic carotid artery disease with acceptable complication rates. The major risk is perioperative embolic stroke. Transcranial Doppler ultrasonography (TCD) can be used to identify embolic signals and guide therapy. We present a case of symptomatic embolization in a 72-year-old female following carotid stent deployment complicated by haemodynamic changes. Despite concurrent dual antiplatelet medication significant symptomatic embolization occurred even after restoration of the blood pressure, and modulation of the rate of embolization was achieved using dextran-40 guided by TCD monitoring. The patient recovered from an initially profound hemiparesis and dysphasia to minor sensory changes. Microemboli are common following carotid artery stenting and there appears to be a threshold phenomenon associated with prolonged embolization and progression to cerebral infarction. TCD can be used to detect particulate microemboli and therefore may be useful in guiding antithrombotic therapy in this setting. Dextran-40 has been shown to reduce the embolic load following carotid endarterectomy and was used to good effect in this patient in terms of both embolic load and clinical outcome. This is the first case of embolization following carotid stenting successfully treated with dextran-40, and offers a further option for therapeutic intervention in microembolism detected by TCD and stresses the importance of perioperative monitoring of embolic load for postoperative stroke risk.

Treatment of a recurrent internal carotid artery pseudoaneurysm with the wallgraft endoprosthesis

SUMMARY

The use of covered stents to treat traumatic carotid artery pseudoaneurysms is increasingly being documented. Adjunctive antiplatelet therapy is mandatory. We present a case of bilateral traumatic carotid artery pseudoaneuryms in which antiplatelet therapy was contraindicated at presentation, thereby dictating alternative treatment with coil embolization alone. Subsequent aneurysmal recurrence was successfully treated with the Wallgraft prosthesis. The literature on the use of the Wallgraft prosthesis for the treatment of carotid artery pseudoaneurysms is also reviewed.

Spontaneous regression of supratentorial intracerebral Langerhans' cell histiocytosis

Langerhans' cell histiocytosis (LCH) describes a group of conditions affecting the reticuloendothelial system. It includes the subtypes of Letterer-Siwe disease, Hand-Schuller-Christian disease and eosinophilic granuloma and most often presents in childhood. Intracranial involvement in LCH is usually restricted to the hypothalamic-pituitary axis or involves extra-axial extension from skull vault lesions. Supratentorial intracerebral lesions with mass effect and enhancement have rarely been described and are not included in the magnetic resonance based classification system of neurological LCH. We present the MRI of a patient with multisystem LCH with spontaneous resolution of enhancing temporal lobe lesions.

Vertebral artery origin angioplasty and primary stenting: safety and restenosis rates in a prospective series

OBJECTIVES

To report a single centre ongoing experience of endovascular treatment for atherosclerotic vertebral artery origin stenosis in a series of symptomatic patients, with follow up imaging to determine the incidence of restenosis.

METHODS

14 patients with vertebral artery origin stenosis on catheter angiography were treated. Angioplasty without stenting was undertaken in the first four patients, all of whom had follow up catheter angiography at one year. Subsequently, patients were treated by primary stenting and followed up with colour Doppler ultrasound examination.

RESULTS

The procedure was technically successful in all treated arteries, with no immediate complications. The degree of stenosis was reduced from (mean (SD)) 73 (18)% before treatment to 21 (26)% immediately after treatment in the angioplasty alone group (p = 0.059). In the primary stenting patients, the severity of stenosis was reduced from 82 (8)% to 13 (13)% immediately after treatment (p < 0.001). Restenosis to 70% or greater occurred at one year in all four patients initially treated by angioplasty without stenting. One patient subsequently developed further symptoms and was retreated by stenting. One of the 10 patients treated by primary stenting developed restenosis. None of the remaining patients had further posterior circulation ischaemic symptoms during a mean follow up period of 33.6 months (range 1 to 72 months).

CONCLUSIONS

Restenosis occurs often after vertebral artery origin balloon angioplasty without stenting but is uncommon after stenting. Primary stenting is therefore recommended to maintain patency at this site, and had a low complication rate in this series.

Radiation protection in interventional radiology

There is growing concern regarding the radiation dose delivered during interventional procedures, particularly in view of the increasing frequency and complexity of these techniques. This paper reviews the radiation dose levels currently encountered in interventional procedures, the consequent risks to operators and patients and the dose reduction that may be achieved by employing a rigorous approach to radiation protection.

Hydrocephalus: comparison of clipping and embolization in aneurysm treatment

OBJECT

In this retrospective study conducted at Atkinson Morley's Hospital and Middlesbrough General Hospital, the authors analyzed 100 matched patients who had suffered subarachnoid hemorrhage (SAH) to determine whether the technical procedure by which aneurysms are treated affects the development of chronic hydrocephalus.

METHODS

Four hundred seventy-five patients presented with SAH between 1995 and 1998. Exclusion criteria included posterior circulation aneurysms, multiple aneurysms, electively clipped or embolized aneurysms, angiographically undetected SAH, patients who died within 1 month of neurosurgical intervention, and patients with the same aneurysm location but a different Fisher grade. The authors matched 50 patients who underwent embolization of their aneurysms with another 50 who had similar Fisher grades and aneurysm types and underwent clipping of their aneurysms. The maximum incidence of ruptured aneurysms occurred in patients who were between 41 and 60 years of age, with women preponderant in both study groups. In each group, 27 patients had anterior communicating artery aneurysm, 13 had posterior communicating artery aneurysm, seven had middle cerebral artery aneurysm, and three had internal carotid artery aneurysm. The lesions in three patients in each group were Fisher Grade I, in 23 patients they were Fisher Grade II, in 14 they were Fisher Grade III, and 10 patients had Fisher Grade IV SAH. Nine patients among those with clipped aneurysms and eight of the patients who underwent embolization had hydrocephalus for which they needed intervention. These interventions included lumbar puncture, ventricular drainage, and ventriculoperitoneal (VP) shunt placement; three patients in each group needed VP shunt placement.

CONCLUSIONS

The technical procedure used to treat aneurysms, whether clipping or embolization, does not significantly affect the development of chronic hydrocephalus. However, a larger sample of patients is needed for accurate comparisons and stronger conclusions.

Fatal cerebral reperfusion hemorrhage after carotid stenting

BACKGROUND

The hyperperfusion syndrome is a recognized complication of carotid endarterectomy. Reports of cerebral hyperperfusion injury following internal carotid artery (ICA) angioplasty are few, and this complication has never been reported following internal carotid stenting.

CASE DESCRIPTION

A 68-year-old normotensive man was referred to our hospital for assessment 5 months after experiencing a left hemispheric ischemic stroke. Angiography confirmed 95% stenosis of the left ICA. Left carotid percutaneous transluminal stenting was performed without any initial complications. Color Doppler ultrasound of the ICA immediately after stenting revealed an elevated peak systolic velocity of 2.3 m/s, in the absence of significant vessel stenosis or spasm on angiography. Seven hours after the procedure, the patient suddenly deteriorated. CT of the brain revealed extensive intracerebral hemorrhage (ICH), and he subsequently died 18 days later. There was no history of headache or seizure activity, and his blood pressure was only mildly elevated at the time of the deterioration. This is the first report of ICH after internal carotid stenting.

CONCLUSIONS

ICH may occur as a hyperperfusion phenomenon after internal carotid stenting, in the presence of mild to moderate arterial hypertension, without being heralded by any of the typical symptoms of the hyperperfusion syndrome. Patients with increased velocities on color Doppler ultrasound of the ICA after angioplasty should be monitored closely for features of cerebral hyperperfusion injury. Further studies are warranted to determine whether more aggressive treatment of mild to moderate hypertension after carotid stenting would reduce the likelihood of this potentially fatal complication.

Dissecting vertebral artery aneurysm: diagnosis and coil embolization

Dissecting aneurysm of the intradural vertebral artery, a rare cause of stroke and sub-arachnoid haemorrhage, is associated with a poor neurological outcome if the disease is unrecognized and remains untreated. Clinical manifestations may be delayed or overlooked and non-invasive radiological investigations demonstrate little or no abnormality. We describe the diagnosis and successful endovascular occlusion of a dissecting vertebral artery aneurysm using detachable microcoils; a novel technique that has advantages over conventional therapeutic procedures.

Should we screen for familial intracranial aneurysm?

BACKGROUND AND PURPOSE

The purpose of this study was to establish whether individuals with a family history of >/=2 first-degree relatives with intracranial aneurysm should be offered screening for aneurysm.

METHODS

We derived 3 theoretical models and calculated the outcomes of screening with magnetic resonance angiography (MRA) followed by digital subtraction angiography (DSA) if MRA was positive (model 1), screening with DSA alone (model 2), and not screening (model 3). Screening was repeated at intervals of 10 years, and aneurysms detected were treated surgically. We assumed a prevalence of aneurysm of 9.8% (95% CI, 8.9% to 10.6%) in the population screened, an annual rupture rate of asymptomatic aneurysm of 0.8% (95% CI, 0.4% to 1.5%), and a 75% chance of poor outcome from rupture. We assumed the sensitivity and specificity of MRA were each 90% and the risk of DSA was 0.1%. The risk of surgery was taken as 5.1%.

RESULTS

Screening 1000 individuals on 3 occasions with MRA and DSA or with DSA alone followed by surgery resulted in poor outcome in 14 and 18 individuals, respectively, over 30 years. Without screening, poor outcome occurred in 15 individuals over the same period of time.

CONCLUSIONS

Screening is not an effective way of reducing morbidity and mortality from ruptured intracranial aneurysm in individuals with a history of >/=2 affected first-degree relatives with ruptured intracranial aneurysm unless the expected incidence of asymptomatic aneurysm is considerably >10%.

Clozapine and risperidone in chronic schizophrenia: effects on symptoms, parkinsonian side effects, and neuroendocrine response

OBJECTIVE

Clozapine and risperidone were the first two "second-generation" antipsychotic drugs approved for schizophrenia. There is currently little information about their comparative efficacy from head-to-head clinical trials. The purpose of this study was to examine the comparative efficacy of clozapine and risperidone for positive and negative symptoms, depression, parkinsonian side effects, and indexes of neuroendocrine function in schizophrenic patients who met a priori criteria for partial response to traditional neuroleptic agents.

METHOD

After a baseline fluphenazine treatment period, 29 patients participated in a 6-week, double-blind, parallel-group comparison of the effects of these agents.

RESULTS

Clozapine was superior to risperidone for positive symptoms and parkinsonian side effects, but there were no significant differences between the drugs on two measures of negative symptoms, Brief Psychiatric Rating Scale total scores, and depression scores. The clozapine patients, but not the risperidone patients, demonstrated significant reductions from the fluphenazine baseline in positive symptoms, total symptoms, and depression. In addition, clozapine produced fewer effects on plasma prolactin than risperidone or fluphenazine. The mean daily doses during week 6 of the trial were 403.6 mg of clozapine and 5.9 mg of risperidone.

CONCLUSIONS

The findings from this study indicate that these drugs have both important differences and similarities in their comparative efficacy in chronically ill, partially responsive patients with schizophrenia. Further research on second-generation antipsychotic drugs in this patient population that addresses key methodological issues, such as optimal dose and treatment duration, are needed.

Treatable lesions demonstrated on vertebral angiography for posterior circulation ischaemic events

Angiography after a posterior circulation ischaemic event is often not considered because of the perception that it will not alter patient management. We identified 53 patients investigated with vertebral angiography over a 5 year period. This was significantly abnormal in 32 patients (60%). Five (9%) had vertebral artery dissections, nine (17%) had unilateral vertebral artery occlusion, two had a basilar artery disease. 16 (30%) had vertebral artery stenosis. 12 stenoses were considered suitable for percutaneous transluminal angioplasty (23%). 11 patients were anticoagulated (21%). There was no significant correlation between clinical features, site of infarct or the presence of carotid stenosis that would have allowed the prediction of the findings in the posterior circulation. Our results indicate that using vertebral angiography to investigate posterior circulation ischaemia will identify a significant number of potentially treatable lesions.

A functional serotonin transporter (5-HTT) polymorphism is associated with psychosis in neuroleptic-free schizophrenics

The neurotransmitter serotonin has been implicated in the pathophysiology of psychosis. The serotonin transporter (5-HTT) plays a critical role in regulation of serotonergic function. A recently identified polymorphism in the promoter region of the 5-HTT gene (5-HTTLPR) produces significant differences in 5-HTT expression and function and was found to be associated with anxiety-related traits in healthy volunteers. We investigated whether 5-HTTLPR is associated with psychosis in neuroleptic-free schizophrenic or schizoaffective patients. Fifty patients with schizophrenia or schizoaffective disorder by DSM-III-R criteria were genotyped at 5-HTTLPR and underwent double-blind Brief Psychiatric Rating Scale (BPRS) ratings while neuroleptic-free for approximately 4 weeks. Patients with the 5-HTTLPR II genotype (n = 19) had significantly higher BPRS ratings for psychosis than patients with the Is (n = 25) or ss (n = 6) genotypes. Examination of individual items revealed a specific significant increase in intensity of hallucinations in patients with the 5-HTTLPR II genotpe. These data provide preliminary evidence for a role of serotonin in the pathophysiology of hallucinations and may represent the identification of an allelic variant that modifies the complex clinical presentation of schizophrenia.

Amyloid angiopathy causing widespread miliary haemorrhages within the brain evident on MRI

The case of a 70-year-old woman with cerebral amyloid angiopathy (CAA) is presented. MRI of the head showed widespread miliary foci of haemorrhage within the cerebrum and cerebellum, with some additional linear lesions within the cerebral cortex and patchy lesions in the white matter. This is in contrast to the more usual pattern of intracranial haemorrhage in CAA, i.e., a lobar haematoma.

Giant aneurysm of the petrous internal carotid artery: diagnosis and treatment

We report the case of a giant fusiform aneurysm of the petrous internal carotid artery in a 15-year-old patient who had presented with headache, hearing loss and Horner's syndrome. Definitive radiological diagnosis was made by non-invasive imaging techniques, including magnetic resonance angiography (MRA). The aneurysm was obliterated by endovascular balloon occlusion following successful tolerance of test occlusion of the internal carotid artery.

The dopamine D3 receptor (DRD3) Ser9Gly polymorphism and schizophrenia: a haplotype relative risk study and association with clozapine response

Several lines of evidence suggest that the dopamine D3 receptor is involved in the pathophysiology of schizophrenia. The D3 receptor gene (DRD3) contains a polymorphism resulting in a serine-glycine substitution in the N-terminus of the receptor. Shaikh and colleagues have reported a significant association between the DRD3 Ser9 allele and the Ser9/Ser9 genotype with schizophrenia in 133 Caucasians. In a meta-analysis of previous studies, Ser9 and the Ser9/Ser9 genotype were found to be significantly associated with schizophrenia, although these investigators could not confirm reports of excess homozygosity at this locus in schizophrenia. These authors also report that, in an unblinded study, the Ser9/Ser9 genotype was more frequent in patients who did not respond to clozapine. These data represent the most comprehensive examination of DRD3 Ser9Gly in schizophrenia to date. We have therefore determined DRD3 Ser9Gly genotypes in 58 patients with schizophrenia and in their parents. Moreover, we have genotyped 68 schizophrenics participating in double-blind clozapine trials. We do not find that Ser9 is preferentially transmitted in schizophrenia, cannot confirm excess DRD3 homozygosity in schizophrenia, and do not replicate the association between DRD3 and clozapine response. These data suggest that allelic variation in DRD3 may not play a role in the pathophysiology of schizophrenia or in clozapine response.

Comparison of hemodynamic cerebral ischemia and microembolic signals detected during carotid endarterectomy and carotid angioplasty

BACKGROUND AND PURPOSE

There has been concern about carotid percutaneous transluminal angioplasty (PTA) carrying a greater risk of cerebral ischemia than carotid endarterectomy. We set out to compare cerebral hemodynamics and microembolization during carotid PTA and CEA.

METHODS

We used transcranial Doppler to monitor the middle cerebral artery of 28 patients undergoing carotid PTA (n = 14) or carotid endarterectomy (CEA) with a shunt (n = 14). Each period during which the internal carotid artery was occluded by PTA balloon or by clamp when the shunt was not in place was timed. Individual periods were summated to give a total occlusion time. Ischemic time was defined as the period for which mean middle cerebral artery velocity fell to a third or less of baseline. Microembolic signals were counted during each procedure.

RESULTS

CEA resulted in significantly longer individual and total occlusion time than PTA (mean individual occlusion time, seconds), CEA, 168 +/- 51; PTA, 20 +/- 7; P < .001; mean total occlusion time; CEA, 337 +/- 70; PTA, 26 +/- 10; P < .001. Ischemic time was also significantly longer during CEA than during PTA (CEA, 165 +/- 40; PTA, 17 +/- 5; P = .001). There were significantly more microembolic signals during PTA than during CEA (mean number of microembolic signals during CEA, 52 +/- 64; during PTA, 202 +/- 119; P = .001). There was no correlation between any of the parameters measured and periprocedural stroke, which occurred in one patient in each group.

CONCLUSION

PTA results in less hemodynamic ischemia but more cerebral microembolism than CEA. In this small series, however, it is not possible to comment on the relations between ischemic time, microembolism, and stroke.

Ketamine-induced exacerbation of psychotic symptoms and cognitive impairment in neuroleptic-free schizophrenics

The N-methyl-d-aspartate (NMDA) receptor has been implicated in the pathophysiology of schizophrenia. We administered subanesthetic doses of the NMDA receptor antagonist ketamine in a double-blind, placebo-controlled design to 13 neuroleptic-free schizophrenic patients to investigate if schizophrenics will experience an exacerbation of psychotic symptoms and cognitive impairments with ketamine. We also examined whether schizophrenics experienced quantitative or qualitative differences in ketamine response in comparison to normal controls. Schizophrenics experienced a brief-ketamine-induced exacerbation of positive and negative symptoms with further decrements in recall and recognition memory. They also displayed greater ketamine-induced impairments in free recall than normals. Qualitative differences included auditory hallucinations and paranoia in patients but not in normals. These data indicate that ketamine is associated with exacerbation of core psychotic and cognitive symptoms in schizophrenia. Moreover, ketamine may differentially affect cognition in schizophrenics in comparison to normal controls.