Phenylpropanolamine contained in cold remedies and risk of hemorrhagic stroke.

In this study, we sought to elucidate whether phenylpropanolamine (PPA) in cold remedies (small and divided doses) increases the risk of hemorrhagic stroke (HS). PPA exposure significantly increased the risk, and the risk was much higher in women. In women, linear trends were also found in recency, duration, and dosage of PPA exposure. PPA contained in cold remedies increases the risk of HS, particularly in women.

Cerebral lipiodol embolism during transcatheter arterial chemoembolization.

Cerebral lipiodol embolism (CLE) is a rare complication that may occur during chemoembolization. The authors present three cases of CLE during transcatheter arterial chemoembolization for hepatocellular carcinoma. Multiple small nonconfluent hyperintense intracerebral lesions were found on the diffusion-weighted and fluid-attenuated inversion recovery MRI. Clinical signs completely resolved and MRI lesions markedly improved on follow-up evaluation within a 3-week period.

Striatocapsular haemorrhage.

Haemorrhages in the striatocapsular area, or striatocapsular haemorrhages (SCHs), have been regarded as a single entity, although the area is composed of several functionally discrete structures that receive blood supply from different arteries. We analysed the morphological and clinical presentations of 215 cases of SCHs according to a new classification method we have designed on the basis of arterial territories. SCHs were divided into six types: (i) anterior type (Heubner's artery); (ii) middle type (medial lenticulostriate artery); (iii) posteromedial type (anterior choroidal artery); (iv) posterolateral type (posteromedial branches of lateral lenticulostriate artery); (v) lateral type (most lateral branches of lateral lenticulostriate artery); and (vi) massive type. The anterior type (11%) formed small caudate haematomas, always ruptured into the lateral ventricle, causing severe headache, and mild contralateral hemiparesis developed occasionally. The outcome was excellent. The middle type (7%) involved the globus pallidus and medial putamen, frequently causing contralateral hemiparesis and transient conjugate eye deviation to the lesion side. About 50% of the patients recovered to normal. The posteromedial type (4%) formed very small haematomas in the posterior limb of the internal capsule and presented with mild dysarthria, contralateral hemiparesis and sensory deficit, with excellent outcome in general. The posterolateral type (33%) affected the posterior half of the putamen and posterior limb of the internal capsule and presented with impaired consciousness and contralateral hemiparesis with either language dysfunction or contralateral neglect. The outcome was fair to poor but there were no deaths. The lateral type (21%) formed large elliptical haematomas between the putamen and insular cortex. Contralateral hemiparesis with language dysfunction or contralateral neglect developed frequently but resolved over several weeks. The clinical outcome was relatively excellent except when the haematoma size was very large. The massive type (24%) formed huge haematomas affecting the entire striatocapsular area. Marked sensorimotor deficits and impaired consciousness, ocular movement dysfunctions including the 'wrong-way' eyes were observed quite frequently. The outcome was very poor with a case fatality rate of 81%. The clinico-radiological presentations suggested its origin was the same as the posterolateral type.

Bilateral intracranial vertebral artery disease in the New England Medical Center, Posterior Circulation Registry.

BACKGROUND: Previous studies of patients with bilateral intracranial vertebral artery (ICVA) disease were selective and retrospective. METHODS: We studied risk factors, vascular lesions, symptoms, signs, and outcomes in patients with bilateral ICVA disease among 430 patients in the New England Medical Center Posterior Circulation Registry. RESULTS: Forty-two patients had bilateral ICVA occlusive disease (18 had bilateral stenosis; 16, unilateral occlusion and contralateral stenosis; and 8, bilateral occlusion). The most common risk factors were hypertension (32/42 [76%]) and hyperlipidemia (22/42 [52%]). Sixteen patients (38%) had transient ischemic attacks (TIAs) only; 18 (43%), TIAs before stroke. Occlusive vascular disease also involved the basilar artery in 29 patients (69%), the extracranial vertebral arteries in 18 (43%), and the internal carotid arteries in 11 (26%). Only 6 patients had no other major vascular lesion. Cerebellar symptoms were common. Among 30 patients with infarction, 21 (70%) had proximal intracranial territory involvement, and 15 (50%) had distal territory involvement. The location of occlusive lesions in relation to posterior inferior cerebellar artery origins did not significantly influence prognosis. During follow-up, 31 patients had no symptoms or slight disability, 2 had progression, and 7 died. Among 7 patients with poor outcome, 6 also had basilar artery stenosis or occlusion and 5 had proximal and distal intracranial territory infarcts. CONCLUSIONS: Most patients with bilateral ICVA occlusive disease have hypertension, other major occlusive lesions, and TIAs before stroke. Short- and long-term outcomes are usually favorable, but patients with bilateral ICVA and basilar artery-occlusive lesions often have poor outcomes.

Middle cerebral artery occlusive disease: the New England Medical Center Stroke Registry.

To analyze the clinical features, vascular lesions, and infarct distribution in Asian and white patients with middle cerebral artery (MCA) territory ischemia, we studied age, sex, race, risk factors, angiographic, and neuroimaging findings among patients in the New England Medical Center Stroke Registry. We included patients with well-defined intrinsic occlusive lesions of the MCAs and patients with embolic MCA territory infarcts. Among 695 patients in the stroke registry, 89 (12.8%) qualified. They had 28 MCA intrinsic stenoses, 17 MCA embolic occlusions (cardiogenic or unknown origin), and 44 carotid artery (CA) stenoses or occlusions. MCA intrinsic disease patients were more often Asians and women, and more often had hypertension. Asians were older than whites. Coronary artery disease (27%), peripheral vascular disease (20.5%), and smoking (39%) were more common in CA disease patients. The most common site of MCA intrinsic stenosis (78%) and embolic occlusion (59%) was the mainstem MCA. Infarcts in patients with MCA intrinsic disease mostly involved the striatocapsular area (61%). Infarcts in patients with MCA embolic occlusion (75%) and CA disease (43%) most often involved the parietal lobe. In our hospital, most patients with MCA intrinsic disease are Asians and women and have hypertension and striatocapsular infarctions. Asian patients are usually older than white patients. The most common site of vascular lesions is the mainstem MCA.

Pulse colliding in a self-mode-locked ring-cavity ti:sapphire laser.

A new self-mode-locked ring-cavity Ti:sapphire laser is described that is self-mode locked in both unidirectional and bidirectional operations. We found that clockwise and counterclockwise pulses collide with each other at the Ti:sapphire rod when the laser is mode locked in a bidirectional operation. Spectrum narrowing and pulse broadening were found in bidirectional rather than unidirectional mode-locked operation. This is explained by the performance of a transient grating in the gain medium that restricts oscillation to a narrow spectral range.

Transmitted photon intensity through biological tissues within various time windows.

The intensity of the early-arriving snake portion of 100-fs ultrashort laser pulses transmitted through biological tissue of increasing thickness was measured by a streak camera. The snake photon intensity within the first arrival time interval Deltat was found to decrease exponentially with tissue thickness (z) as I(Deltat) = I(0)A exp[-b(Deltat)z/l(t)], where I(0) is the incident laser pulse intensity, l(t) is the transport mean free path of the medium, and the parameters b and A depend on the time interval Deltat. This result shows that the intensity of snake photons decays significantly more slowly than that of ballistic photons as tissue thickness increases.

Effect of multiple light scattering and self-absorption on the fluorescence and excitation spectra of dyes in random media.

The absorption, fluorescence, and excitation spectra of a dye in a highly scattering random medium were studied experimentally. The intrinsic absorption spectrum of the dye does not change in the presence of scatterers, but the presence of scatterers in the media will change the observed fluorescence spectra. The observation is accounted for by the change in the photon trajectory path length for the fluorescence emission.

Should the photon flux or the photon density be used to describe the temporal profiles of scattered ultrashort laser pulses in random media?

The temporal profiles of ultrashort laser pulses scattered in random media with different experimental geometries were measured and analyzed by using the photon flux and the photon density predicted by the diffusion theory. The scattered laser pulse profiles detected by an optical fiber inside an infinite random medium are found to be described by the photon density. For a semi-infinite medium, the scattered pulse profile emitted from the surface of the medium can be described by either the photon density or the photon flux. These results can be consistently explained by the diffuse intensity (radiance) of transport theory.

Self-bending of light.

The supercontinuum light generated by oblique intense 100-fs ultrafast laser pulses was found to bend from the direction of the incident pulses. The emission direction of the anti-Stokes continuum that is due to self-phase modulation bends to one side, while the conical ring that is due to four-photon parametric generation bends to the other side. The self-bending of supercontinuum emissions is attributed to the spatial variation of the refractive index induced by the oblique pulse front, which causes the refraction of light for self-phase-modulation emission and the bending of the wave vector for the four-photon parametric generation.

Spectral optical-density measurements of small particles and breast tissues.

The optical density of breast tissues without blood is found to be relatively constant from 320 to 800 nm, indicating a relatively independent scattering cross section over this wavelength region.

Ultrafast laser-pulse transmission and imaging through biological tissues.

The transmission of 100-fs ultrafast laser pulses through biological tissues was measured by using femtosecond and picosecond time-resolved detection techniques. The broadening of transmitted pulses was found to increase as the thickness of the biological tissue increases. The absence of a distinct ballistic pulse transmitted through a relatively thin tissue is in sharp contrast with the pulse transmission through a random medium of discrete scatterers. Because of the continuous variation of the dielectric constant in tissue, the photons undergo scattering through the tissue, travel in various small zigzag least optical paths, and form a broadened early-arriving portion of the transmitted pulse. Even in the absence of a well-defined ballistic pulse, we can image an opaque object hidden inside a tissue as thick as 6.5 mm with submillimeter resolution by selecting the early-arriving portion of the transmitted pulse.

Conical emission by four-photon parametric generation by using femtosecond laser pulses.

Conical continuum Stokes and anti-Stokes emissions are observed when intense 100-fs/620-nm ultrafast laser pulses propagate through an ethylene glycol medium. The angle of the anti-Stokes conical emission is modeled by class-II Raman and four-photon parametric generations in a small-scale filament with a nonlinear index change.

Raman, fluorescence, and time-resolved light scattering as optical diagnostic techniques to separate diseased and normal biomedical media.

Studies of Raman scattering, fluorescence and time-resolved light scattering were conducted on cancer and normal biomedical media. Fourier transform Raman spectroscopic measurements were performed on human normal, benign and cancerous tissues from gynecological (GYN) tracts. A comparison of the intensity differences between various Raman modes as well as the number of Raman lines, enables one to distinguish normal GYN tissues from diseased tissues. Fluorescence spectroscopic measurements on human breast tissues show that the ratio of fluorescence intensity at 340 nm to that at 440 nm can be used to distinguish between cancerous and non-cancerous tissues. Separate studies on normal and cancerous breast cell lines show spectral differences. The measurements of back-scattered ultrafast laser pulses from human breast tissues show differences in the scattered pulse profiles for different tissues. These studies show that various optical techniques have the potential to be used in medical diagnostic applications.

Imaging of a translucent object hidden in a highly scattering medium from the early portion of the diffuse component of a transmitted ultrafast laser pulse.

A translucent object hidden in a highly scattering medium is shown to be visible when the early portion of the transmitted diffuse pulse (snake photons) is detected. The use of the snake scattered photons to image objects depends on the scattering characteristics along a quasi-straight-line path that the photons traverse across the medium. A translucent object with different scattering characteristics compared with its surrounding medium will change the intensity of the snake photons. By scanning the medium across the laser beam and detecting only the snake photons, a translucent object hidden in a highly scattering medium could be located.

Speed of the coherent component of femtosecond laser pulses propagating through random scattering media.

The pulse profile and the speed of the coherent component of 85-fs laser pulses propagating through a slab of a random scattering medium were measured. The pulse profile was found to remain essentially the same, while the speed was reduced proportionally to the thickness of the slab and the concentration of the scatterers. The reduction in speed can be accounted for by an effective index of refraction that is described either by the volume fractional combination of the indices of refraction of the scatterers and the water or by the coherent interference between the scattered waves and the primary wave.