Neurons in the premotor cortex of macaques respond to tactile, visual and auditory stimuli. The distribution of these responses was studied in five anesthetized monkeys. In each monkey, multiunit activity was studied at a grid of locations across the precentral gyrus. A cluster of sites with polysensory responses was found posterior to the genu of the arcuate sulcus. Tactile and visual responses were represented in all five monkeys, while auditory responses were rarer and found in only two monkeys. This polysensory zone (PZ) was located in the caudal part of premotor cortex. It varied in extent among the monkeys. It was mainly ventral to the genu of the arcuate, in the dorsal and caudal part of the ventral premotor cortex (PMv). In some monkeys it extended more dorsally, into the caudal part of dorsal premotor cortex (PMd). Sensory responses were almost never found in the rostral part of PMd. We suggest that the polysensory zone may contribute to the guidance of movement on the basis of tactile, visual and auditory signals. 相似文献
Following the initial, sensory response to stimulus presentation, activity in many saccade-related burst neurons along the oculomotor neuraxis is observed as a gradually increasing low-frequency discharge hypothesized to encode both timing and metrics of the impending eye movement. When the activity reaches an activation threshold level, these cells discharge a high-frequency burst, inhibit the pontine omnipause neurons (OPNs) and trigger a high-velocity eye movement known as saccade. We tested whether early cessation of OPN activity, prior to when it ordinarily pauses, acts to effectively lower the threshold and prematurely trigger a movement of modified metrics and/or dynamics. Relying on the observation that OPN discharge ceases during not only saccades but also blinks, air-puffs were delivered to one eye to evoke blinks as monkeys performed standard oculomotor tasks. We observed a linear relationship between blink and saccade onsets when the blink occurred shortly after the cue to initiate the movement but before the average reaction time. Blinks that preceded and overlapped with the cue increased saccade latency. Blinks evoked during the overlap period of the delayed saccade task, when target location is known but a saccade cannot be initiated for correct performance, failed to trigger saccades prematurely. Furthermore, when saccade and blink execution coincided temporally, the peak velocity of the eye movement was attenuated, and its initial velocity was correlated with its latency. Despite the perturbations, saccade accuracy was maintained across all blink times and task types. Collectively, these results support the notion that temporal features of the low-frequency activity encode aspects of a premotor command and imply that inhibition of OPNs alone is not sufficient to trigger saccades. 相似文献
β-Aminopropionitrile as free base (BAPN) was applied onto the incised or intact skin of rats at the dose of 5, 20, 100, and 200 μl for 9 days, twice daily. Breaking strength of the skin wound or intact skin was significantly reduced at doses of 20 μl and higher; body weight growth was significantly retarded at the two highest dosages. It is concluded that at a given dose (20 μl) collagen polymerization (evaluated by reduced breaking strength and increased extractability of collagen) was specifically inhibited by BAPN. Furthermore, no evidence of topical or general toxic effects were observed, as reflected in histology, body weight growth, and behavior of the rats. Acute LD50 of BAPN base and fumarate, administered either ip or topically, was determined in mice. While BAPN base in ip administration shows LD50 of 1.15 g/kg, in cutaneous application it is more than 12.8 g/kg. It is suggested that topically applied BAPN base is percutaneously absorbed and affects collagen polymerization in the skin and adjacent tissues. 相似文献
We present an empowerment model that fosters strengths and promotes positive identity development among adolescent females of color. Race, ethnicity, gender, and socioeconomic status are integrated in an African American context. A case study illustrates a strength-based approach to conceptualizing and treating a young, Black adolescent female in her cultural context. We conclude with clinical implications for using an empowerment-based approach in psychotherapy with culturally diverse adolescent females. 相似文献
Endometriosis is subsequent to the ability of endometrial glands to invade normal tissues. Matrix metalloproteinases (MMPs)—enzymes that mediate normal tissue turnover, including endometrial breakdown during menstruation—appear to be involved in this invasive process. Here, we examined the immunohistochemical expression of MMP-2, MMP-3, MMP-11, tissue inhibitor metalloproteinase (TIMP)-1 and TIMP-2 in endometrium from women with (n=9) or without endometriosis (n=18) in comparison with peritoneal (n=20), ovarian (n=20) and colorectal endometriosis (n=20). Women with endometriosis showed decreased endometrial MMP-2 expression compared with women without endometriosis (mean±SD positive cells: 24.3±28.3% and 69.3±12.1%), together with loss of MMP-3 expression (0 versus 17.5%±20.2). MMP-11, TIMP-1 and TIMP-2 expression was similar in the two groups. Endometrial MMP-2, -3 and -11 expression and TIMP-1 and -2 expression were similar in women with endometriosis and in those with peritoneal endometriosis. MMP-2, -3 and -11 expression was higher in colorectal endometriosis than in ovarian and peritoneal endometriosis. TIMP-2 expression was lower in colorectal endometriosis (P=0.0002) and ovarian endometriotic cysts (P=0.003) than in peritoneal endometriosis. TIMP-1 expression did not vary according to the location of endometriotic lesions. These results suggest that MMP-2 and -3 and TIMP-2 may be involved in the pathogenesis of endometriosis. Interestingly, MMP-2 and -3 overexpression was related to the infiltrative nature of endometriotic lesions, with possible sequential expression from peritoneal to colorectal endometriosis. 相似文献
BACKGROUND: Perinatal HIV transmission has declined significantly in New York State (NYS) since implementation of a 3-part regimen of zidovudine prophylaxis in the antenatal, intrapartum, and newborn periods. This study describes the factors associated with perinatal transmission in NYS from 1997 to 2000, the first 4 years of NYS's comprehensive program in which all HIV-exposed newborns were identified through universal HIV testing of newborns. METHODS: This population-based observational study included all HIV-exposed newborns whose infection status was known and their mothers identified in NYS through the universal Newborn HIV Screening Program (NSP) from February 1997 to December 2000. Antepartum, intrapartum, newborn, and pediatric medical records of HIV-positive mothers/infants were reviewed for history of prenatal care, antiretroviral therapy (ART), and infant infection status. Risks associated with perinatal HIV transmission were examined. RESULTS: Perinatal HIV transmission declined significantly from 11.0% in 1997 to 3.7% in 2000 (P < 0.05). Prenatal ART was associated with a decline in perinatal HIV transmission both for monotherapy (5.8%, relative risk [RR] = 0.3, 95% confidence interval: 0.2%-0.5%) and combination therapy [2.4%, RR = 0.1, 95% confidence interval: 0.1%-0.2%) compared with no prenatal antiretroviral prophylaxis (P < 0.05). CONCLUSIONS: Public health policies to improve access to care for pregnant women and advances in clinical care, including receipt of appropriate preventive therapies, have contributed to declines in perinatal HIV transmission in NYS. 相似文献
Despite the obstacles of limited education and employment opportunities—and the stress associated with immigration and pregnancy—Mexican immigrant women have low rates of preterm birth (PTB) compared to the US national average for all races and ethnicities. Stressors during pregnancy, and stressors associated with acculturation, may accelerate cellular aging manifested by shortened telomere length (TL) in pregnant women. Our objectives were to: (1) determine whether women with PTBs had shorter telomere lengths compared to women who had full term births; (2) assess the association of acculturation with TL and PTB.
Methods
This prospective pilot study collected data from 100 self-identified Mexican-origin pregnant women. Survey data included self-administered sociodemographic and acculturation measures and was collected from participants via paper and pen, while biologic data was collected via a single blood draw during a regularly scheduled prenatal visit between 26 and 36 weeks gestation. PTB data was collected from the participant’s medical record after delivery.
Results
TL was significantly associated with PTB; the median TL of the women with PTB was less than the median TL for the full sample (p?=?0.02). Based on regression analysis for PTB vs acculturation, we found no significant associations between acculturation and PTB or TL.
Conclusions for Practice
This study provides important evidence of the association between shortened maternal TL and adverse birth outcomes. By linking social, clinical and biologic data, we can enhance our understanding of social determinants that may affect racial and ethnic disparities in preterm birth.