Potential role in seed dispersal revealed by experimental trials with captive southern muriquis (Brachyteles arachnoides).

Primates are great fruit consumers and disperse intact seeds from most of the plants they consume, but effective seed dispersal depends, amongst other factors, on handling behavior. Likewise, the treatment in gut and mouth may alter seed fate. Overall, frugivore and folivore-frugivore primates are recognized to provide beneficial gut treatment for Neotropical plant species, but this effect might be overlooked at species-specific levels. In this study, we assessed the role of the southern muriqui (Brachyteles arachnoides), an endangered and endemic primate living in restricted fragments of the Brazilian Atlantic Forest, on potential quality of seed dispersal of native plants. Our main goals were to understand the effect of seed ingestion by this large-bodied atelid on germination of defecated seeds and in seed recovery by offering wild fruits of native species to captive individuals. We found that seven out of nine plant species were defecated intact and were able to germinate. Of those seven, one species showed enhanced and another showed decreased germination potential after defecation, while three species germinated faster after being defecated. The remaining species showed no differences from control seeds. The two non-germinating species were heavily predated, and average seed recovery was lower than expected, suggesting high levels of seed predation. The largest species offered (Inga vulpina) showed the highest dispersal potential. Our data support an overall neutral or potentially positive role of southern muriquis in seed dispersal quality for seven out of nine Atlantic Forest plant species, highlighting these primates' potential to produce an effective seed rain.

Morphological and functional characteristics of patent foramen ovale and their embolic implications.

BACKGROUND AND PURPOSE: Transesophageal echocardiography (TEE) has detected a high prevalence of patent foramen ovale (PFO) in stroke patients, but the clinical implications of the distinctive characteristics of this patency are still a matter of debate. METHODS: We studied 350 patients with acute ischemic stroke or transient ischemic attack (TIA) within 1 week of admission. Of these, 101 (29%) were identified by contrast TEE to have a PFO; 86 patients (25%) were cryptogenic stroke patients, and 163 were excluded because of the presence of a definite or possible arterial or clinical evidence of a source of emboli or small-vessel disease. Thirteen PFO subjects without a history of embolism were designated as the control group. All PFO and cryptogenic stroke patients were followed up by neurological visits. RESULTS: Compared with controls, PFO patients with acute stroke or TIA more frequently presented with a right-to-left shunt at rest and a higher membrane mobility (P:<0. 05). Patients with these characteristics were considered to be at high risk. During a median follow-up period of 31 months (range, 4 to 58 months), 8 PFO and 18 cryptogenic stroke patients experienced recurrent cerebrovascular events. The cumulative estimate of risk of cerebrovascular event recurrence at 3 years was 4.3% (95% confidence interval [CI], 0% to 10.2%) for "low-risk" PFO patients, 12.5% (95% CI, 0% to 26.1%) for "high-risk" PFO patients, and 16.3% (95% CI, 7. 2% to 25.4%) for cryptogenic stroke patients (high-risk PFO versus low-risk PFO, P:=0.05). CONCLUSIONS: The association of right-to-left shunting at rest and high membrane mobility, as detected by contrast TEE, seems to identify PFO patients with cerebrovascular ischemic events who are at higher risk for recurrent brain embolism.

Early spontaneous improvement and deterioration of ischemic stroke patients. A serial study with transcranial Doppler ultrasonography.

BACKGROUND AND PURPOSE: The purpose of our study was to investigate whether emergency transcranial Doppler (TCD) findings and their modifications over the first 48 hours are related to early neurological changes in acute ischemic stroke patients. METHODS: Ninety-three patients underwent CT scan within 5 hours of a first-ever ischemic hemispheric stroke, and TCD serial examinations at 6, 24, and 48 hours after stroke onset. We classified TCD findings as follows: normal; middle cerebral artery (MCA) asymmetry (asymmetry index between affected and contralateral MCAs below -21%); and MCA no-flow (absence of flow signal from the affected MCA in the presence of ipsilateral anterior and posterior cerebral artery signals through the same acoustic window). We considered early deterioration and early improvement to be a decrease or an increase of 1 or more points, respectively, in the Canadian Neurological Scale score over the same period. RESULTS: At 6-hour TCD examination, MCA asymmetry and MCA no-flow were present in 6 (22%) and 2 (7%), respectively, of 27 improving patients; in 20 (43%) and 10 (22%) of 46 stable patients, and in 9 (45%) and 8 (40%) of 20 deteriorating patients. TCD findings were normal in the remaining patients (P = 0.001). At serial TCD, we detected early (within 24 hours) recanalization (from no-flow to asymmetry or normal and from asymmetry to normal) in 2 (25%) improving patients, in 7 (23%) stable patients, and in 5 (29%) deteriorating patients and late (between 24 and 48 hours) recanalization in 4 (50%) improving patients, in 6 (20%) stable patients, and in none of the deteriorating patients (P = 0.03, chi 2 for trend, improving versus nonimproving irrespective of the timing of recanalization). One deteriorating patient (5%) developed a non-flow from an initial MCA asymmetry. Logistic regression selected normal TCD (odds ratio [OR], 0.17; 95% confidence interval [CI], 0.06 to 0.46) as an independent predictor of early improvement and abnormal TCD (asymmetry plus no-flow) (OR, 5.02; 95% CI, 1.31 to 19.3) as an independent predictor of early deterioration. CONCLUSIONS: TCD examination within 6 hours after stroke can help to predict both early deterioration and early improvement. Serial TCD shows that propagation of arterial occlusion is rarely related to early deterioration, whereas the fact that it can detect early recanalization (within 24 hours) in deteriorating patients and both early and late recanalization (after 24 hours) in improving patients suggests the existence of individual time frames for tissue recovery.

Patent foramen ovale and transcranial Doppler. Comparison of different procedures.

BACKGROUND AND PURPOSE: The capability of transcranial Doppler sonography (TCD) to detect a patent foramen ovale (PFO) has been established. However, which provocative maneuver and what timing of contrast injection are most effective to induce a right-to-left shunt has not yet been determined. METHODS: We selected 38 cerebrovascular patients (21 men, 17 women) with positive contrast study for PFO on transesophageal echocardiography. Patients underwent a TCD with bilateral monitoring of the middle cerebral arteries (MCAs) and injection of a contrast solution. The injection was repeated (1) during normal breathing (basal conditions); (2) before Valsalva maneuver (VM); (3) during VM; (4) immediately after VM; and (5) during cough. The latency time and the total number of microbubbles for each side were recorded. RESULTS: TCD found positive results for PFO in 30 patients. Twenty were positive even during basal conditions. The number of positive cases varied according to the timing of the VM in relation to the contrast injection: 28, 25, and 27 cases were positive when the injection was performed before, during, and after VM, respectively, while 26 were positive during cough. There were significant differences in the number of microbubbles in the MCAs between the procedures (P < .001, ANOVA): the highest number was detected in the injection before VM and the lowest number during basal conditions (P < .001, Wilcoxon's test with Bonferroni's correction). The latency time was significantly shorter when the injection followed VM. CONCLUSIONS: The injection performed before VM appeared to be the most effective TCD procedure in determining the transit of microbubbles through a PFO and subsequently in the MCAs.

Clinical and prognostic correlates of stroke subtype misdiagnosis within 12 hours from onset.

BACKGROUND AND PURPOSE: Pure motor hemiparesis and sensorimotor stroke syndromes are not accurate predictors of lacunar infarct when described in the first 12 hours of stroke onset. We evaluate here whether this inaccuracy of clinical diagnosis might have influenced the planning of patient management either in routine practice or in therapeutic trials. METHODS: A consecutive hospital series of 517 first-ever ischemic hemispheric stroke patients presented lacunar or nonlacunar syndromes at the first examination within 12 hours of the event. A distinction was subsequently made, by means of a CT scan or autopsy performed within 15 +/- 2 days of stroke, between patients affected by lacunar or nonlacunar infarcts. We compared stroke risk factors, considered to be indicative of potential pathogenetic mechanisms, and the clinical outcome of lacunar infarct versus nonlacunar infarct patients and those of lacunar syndrome versus nonlacunar syndrome patients. RESULTS: Two hundred nineteen patients (42%) presented a lacunar syndrome and 298 (58%) a nonlacunar syndrome, while 170 (33%) had lacunar infarcts and 347 (67%) nonlacunar infarcts. Lacunar infarct patients were more frequently associated with hypertension and a previous transient ischemic attack and less frequently with atrial fibrillation when compared with their nonlacunar infarct counterparts, whereas no differences were apparent between lacunar syndrome and nonlacunar syndrome patients. Logistic regression analysis showed that hypertension and a previous transient ischemic attack on the one hand and atrial fibrillation on the other were strongly correlated with the diagnosis of lacunar infarct and nonlacunar infarct, respectively, while no risk factor was correlated with the diagnosis of lacunar syndrome. Twenty-two percent of lacunar infarct patients and 68% of nonlacunar infarct subjects had a poor outcome (death plus disability of survivors) as opposed to 40% of lacunar syndrome and 63% of nonlacunar syndrome patients. Logistic regression selected age, severity of neurological deficit at entry, cardiopathies, diabetes, and lacunar infarct, but not lacunar syndrome, as predictors of outcome. CONCLUSIONS: The inaccurate clinical diagnosis of lacunar infarct made in the first 12 hours of stroke might lead to no distinction being made between stroke subgroups with potentially different pathogenetic mechanisms and prognostic estimates, thus negatively influencing the planning of patient management.

Spontaneous middle cerebral artery reperfusion in ischemic stroke. A follow-up study with transcranial Doppler.

BACKGROUND AND PURPOSE: The aim of this study was to investigate by means of transcranial Doppler (TCD) ultrasonography how many spontaneous reperfusions of the middle cerebral artery (MCA) occurred during the first week after onset of acute ischemic stroke in the carotid territory. METHODS: TCD examination, computed tomographic scan, and arterial digital angiography were performed in 56 patients with acute ischemic stroke within 6 hours of the onset of symptoms. The TCD examination was repeated within 24 hours, 48 hours, and 7 days after stroke; a further TCD examination was performed within 3 to 9 months in 27 patients. RESULTS: At 6 hours, 33 patients presented abnormal TCD findings in the symptomatic MCA (16 "no flows" and 17 asymmetries). Of these, 4 patients (3 no flows and 1 asymmetry) died before the 7-day follow-up was completed, whereas of the 29 remaining patients undergoing all the TCD control examinations, only 14 presented permanently abnormal TCD findings (7 asymmetries and 7 no flows). These data are consistent with an MCA reperfusion occurring at any level of the MCA, although most frequently in the distal part, and in the majority of cases during the first 48 hours. One patient who showed MCA asymmetrical flow velocity at the day-7 TCD examination was normal at the TCD follow-up at 3 to 9 months. CONCLUSIONS: TCD examination offers an easy and reliable way of monitoring MCA reopening and might be useful to identify subgroups of patients who may benefit most from pharmacological reperfusion.

Transcranial Doppler in spontaneous attacks of migraine.

BACKGROUND AND PURPOSE: Our aim in this study was to compare headache-free and spontaneous migraine measurements of blood flow velocity and the pulsatility index in the anterior cerebral artery, middle cerebral artery, and posterior cerebral artery. METHODS: Thirty-one patients (nine having experienced migraine with aura and 22 migraine without aura) were studied in headache-free periods and during spontaneous migraine attacks with transcranial Doppler ultrasonography. RESULTS: During attacks of migraine with aura, blood flow velocities (particularly the diastolic velocity [p = 0.05]) were reduced while the pulsatility index increased (p = 0.05), whereas a generalized increase in diastolic velocity (p less than 0.02) and a decrease in the pulsatility index (p = 0.05) were observed during attacks of migraine without aura. Significant variations of blood pressure and heart rate were never found. CONCLUSIONS: These findings are consistent with constriction of resistance vessels in migraine with aura and dilatation of the vessels in migraine without aura. This disparity could be due to a difference between the two migraine types or could be related to the fact that in this study the time interval between headache onset and transcranial Doppler was shorter in the migraine-with-aura group. The latter explanation would apply if, in fact, both types of migraine evolve from hypoperfusion to hyperperfusion during their time course, although perhaps with a difference in intensity.

Transcranial Doppler (TCD) after nitroglycerin in migraine without aura.

Nitroglycerin, a vasodilating agent, was administered sublingually in migraine without aura patients and in healthy volunteers. Systolic, diastolic and time-mean flow velocity and pulsatility index, were measured by transcranial Doppler sonography in the major intracranial arteries before and after nitroglycerin administration. Following nitroglycerin administration, a significant decrease in systolic and time-mean velocity and pulsatility index was observed in migraine patients, whereas in control subjects only time-mean velocity decreased significantly. Based on those findings we hypothesize a more marked responsiveness to nitroglycerin in migraine patients as compared to healthy subjects.

Transcranial Doppler in acute hemispheric brain infarction.

We studied cerebrovascular anatomy using intra-arterial digital angiography, and blood flow velocity in the middle cerebral artery (MCA) using transcranial Doppler (TCD) ultrasonography in 42 patients with acute hemispheric ischemic brain infarction. We compared angiography with TCD and the clinical findings within 6 hours of the onset of symptoms. The location and extent of the chronic ischemic brain damage was assessed by CT performed 1 to 3 months after the ictus. Abnormal TCD, as manifested by either an unobtainable MCA flow signal or a significantly depressed MCA flow velocity, was highly associated with proximal MCA occlusions demonstrated by angiography. Abnormal TCD predicted both larger chronic CT lesions and more extensive ischemic change within the MCA territory. These data demonstrate that early TCD conveys useful information concerning cerebral tissue prognosis following hemispheric ischemia.

Comparison of cerebral angiography and transcranial Doppler sonography in acute stroke.

We compared digital intra-arterial angiography and transcranial Doppler sonography in acute cerebral ischemia as part of a wider study on a continuous series of 48 patients with acute focal cerebral ischemia in the carotid territory, observed within 4 hours of the onset of symptoms. The most significant Doppler findings of the middle cerebral artery included no detection of the artery when occlusion of the carotid siphon or the middle cerebral artery at its origin was shown by angiography and reduced flow velocities and asymmetry (symptomatic less than asymptomatic) when the occlusion was located in the terminal tract of the middle cerebral artery mainstem or in numerous terminal branches. Higher flow velocities in the anterior cerebral artery or posterior cerebral artery, mostly in the symptomatic hemisphere, often accompanied middle cerebral artery pathology, probably indicating collateral compensatory pathways.