Comparison of Sexual and Drug Use Behaviors Between Female Sex Workers in Tijuana and Ciudad Juarez,Mexico

Female sex workers (FSWs) have been documented to have high rates of sexually transmitted diseases and HIV in many parts of the world. However, little work has been done to characterize the prevalence of these infections along the U.S.–Mexican border, where sexual tourism and culturally sanctioned sex work among nationals is widespread. The objective of this study was to compare differences in background characteristics, HIV risk behaviors, drug use, and sexually transmitted infection/HIV prevalence between FSWs who participated in a behavioral risk intervention in two U.S.–Mexican border cities. Baseline data were collected from March 2004 through September 2005. Data from 295 FSWs were compared between Tijuana and Ciudad (Cd.) Juarez. Among 155 FSWs in Tijuana and 140 in Cd. Juarez, HIV seroprevalence was 4.8% and 4.9%, respectively. FSWs in Cd. Juarez were more likely to test positive for active syphilis (31.3%) compared with Tijuana (11.8%) but did not differ in terms of the prevalence of gonorrhea and chlamydia. FSWs in both sites reported high levels of unprotected sex and use of drugs; however, FSWs in Cd. Juarez were more likely than those in Tijuana to ever have injected drugs (75% vs. 25%, p <.001). Heroin and cocaine use and injection drug use were significantly more common in Cd. Juarez, whereas methamphetamine use was more common in Tijuana. Injection of vitamins was common in both cities. Logistic regression analyses suggested that being younger, working in Cd. Juarez, and using heroin or cocaine were independently associated with active syphilis infection. In Tijuana, methamphetamine use was strongly associated with active syphilis infection. These preliminary results suggest that risk profiles for HIV/sexually transmitted infection among FSWs in these two Mexico–U.S. border cities differ, suggesting a need to tailor interventions to the specific needs in each city.     

Clinicopathological study of invasive ductal carcinoma with large central acellular zone: special reference to magnetic resonance imaging findings

Invasive ductal carcinoma (IDC) with central acellular zone is sometimes encountered, but its clinicopathological features have not yet been fully investigated. The clinicopathological features of 10 resected cases of IDC with a large central acellular zone were investigated. The tumor size ranged from 6 to 28 mm with a mean of 14.3 +/- 6.9 mm. Contrast-enhanced magnetic resonance imaging (MRI) showed a ring-like appearance in the tumor. Sagittal fat-suppressed T2-weighted MRI had very high to intermediate signal intensity in a central area. Histologically, cancer tissue was located in the periphery of the tumor with a ring-like pattern and a large central area was occupied by acellular amorphous tissue that was strongly stained by alcian blue. Lymph vessel permeation was seen in eight cases. Among the tumors with focal enhancement in the central areas >1 cm in diameter on contrast MRI, marked increase of microvessel was observed in the enhanced spot. The mean of p53 and Ki-67 labeling indices was 56.2% and 36.3%, respectively. IDC with a large central acellular zone presenting with characteristic MRI should be noted as a new morphological entity.     

Delta EEG activity as a marker of dysfunctional linguistic processing in developmental dyslexia

The present study used delta EEG band to test the hypothesis of a cerebral maturational delay and a functional altered cerebral asymmetry for phonological processing in dyslexic children. A group of 14 children with dyslexia and 28 matched controls participated in a linguistic paradigm in which the same words were processed in three tasks: phonological, semantic, and orthographic. Delta amplitude was computed as an index of cortical inhibition in four different phases of word processing. In anterior sites, controls showed left activation (reduced delta) during the phonological task and bilateral activation in the other two tasks. Conversely, children with dyslexia showed greater overall delta amplitude, indexing a cerebral maturation delay and an altered language laterality pattern. In the phonological task they had larger left anterior delta (inhibition of left frontal linguistic locations) and smaller left posterior delta amplitude (activation of left posterior sites silent in controls). Results support the phonological deficit hypothesis of developmental dyslexia and the validity of EEG delta band as functional and clinical measure of language laterality.     

Inversion of contrast polarity abolishes spontaneous preferences for face-like stimuli in newborn chicks

A spontaneous preference for face-like stimuli has been demonstrated in domestic chicks, similar to that shown by human newborns, suggesting evolutionary continuity across species. Inversion of contrast polarity of face-like stimuli abolishes face preferences in human newborns. Here we investigated the effects of contrast polarity inversion and brain lateralization in chicks’ preferences for faces. In Experiment 1 face-naïve chicks were tested with a negative face obtained from a stimulus that elicited preferential approach in previous research. As in human newborns, reversal of contrast polarity abolished face-preferences. Experiments 2, 3 and 5 investigated the effect of adding a pupil-like dot within the inner features of the negative and of positive stimuli (a manipulation that re-established face-preference in human newborns). Chicks reacted to this by avoiding the face stimulus. In Experiments 4 and 6 we found that the preference expressed by chicks having only their left eye (right hemisphere) in use changed according to contrast polarity, whereas it remained unaffected in chicks having their right eye in use. Thus, in domestic chicks, as in human beings, a stimulus is perceived as face-like only if it presents the correct luminance pattern expected for a face under natural top-lit illumination and the right hemisphere seems to play a crucial role in this kind of social orienting responses.     

Premotor and occipital theta asymmetries as discriminators of memory- and stimulus-guided tasks

The saccadic paradigm has been used to investigate specific cortical networks involving visuospatial attention. We examined whether asymmetry in theta and beta band differentiates the role of the hemispheres during the execution of two different prosacadic conditions: a fixed condition, where the stimulus was presented at the same location; and a random condition, where the stimulus was unpredictable. Twelve healthy volunteers (3 male; mean age: 26.25) performed the task while their brain activity pattern was recorded using quantitative electroencephalography. We did not find any significant difference for beta, slow- and fast-alpha frequencies for the pairs of electrodes analyzed. The results for theta band showed a superiority of the left hemisphere in the frontal region when responding to the random condition on the right, which is related to the planning and selection of responses, and also a greater activation of the right hemisphere during the random condition, in the occipital region, related to the identification and recognition of patterns. These results indicate that asymmetries in the premotor area and the occipital cortex differentiate memory- and stimulus-driven tasks.     

Correlation of EEG, neuroimaging and histopathology in an epilepsy patient with diffuse cortical dysplasia

The correlation between scalp EEG, intraoperative electrocorticogram, neuroimaging and histopathology was examined in an epileptic child with diffuse cortical dysplasia. The 6-year-old girl with moderate mental retardation had suffered from intractable complex partial and generalized epilepsies since the age of 2 years. MR images demonstrated unilateral large macrogyria/polymicrogyria and schizencephaly in the right occipital lobe. The epileptic focus was detected on the macrogyria by EEG and single photon emission tomography. However, the intraoperative electrocorticogram showed frequent spikes from the polymicrogyria and no paroxysmal activity in the macrogyria. The polymicrogyria and the macrogyric lesion were resected, using an image-guided system. The histological findings revealed that the macrogyria was covered with and separated by glial bundles. It has been reported that epileptogenicity is produced from abnormal neurons and their arrangement in cortical dysplasia; in this case, however, the major dysplastic lesion had no epileptogenicity; rather the focus might be in the polymicrogyria around the lesion. Received: 18 November 1998 Revised: 19 February 1999     

Basic and clinical neuroscience applications of embryonic stem cells

There have been recent dramatic advances in our understanding of the molecular mechanisms governing the elaboration of mature tissue‐specific cellular subpopulations from embryonic stem (ES) cells. These investigations have generated a range of new biological and potential therapeutic reagents to allow us to dissect specific stages of mammalian development that were previously experimentally inaccessible. Ultimately, we will be able to reconstitute seminal signaling pathways to promote regeneration of the nervous system. Totipotent ES cells possess an unlimited proliferative capacity that make them attractive candidates for use in a series of innovative transplantation paradigms. Elucidation of the molecular and physiologic properties of ES cells also has important implications for our understanding of the integrative cellular processes underlying neural induction, patterning of the neural tube, neural lineage restriction and commitment, neuronal differentiation, regional neuronal subtype specification, and the specific pathological consequences of alterations in discrete components of these fundamental neurodevelopmental pathways. In addition, recent experimental observations suggest that neurodegenerative disease pathology may involve alterations in a range of progressive neural inductive and neurodevelopmental events through novel biological mechanisms that result in sublethal impairments in cellular homeostasis within evolving regional neuronal precursor populations containing the mutant proteins, culminating in increased vulnerability of their differentiated neuronal progeny to late‐onset apoptosis. Future discoveries in ES cell research will offer unique conceptual and therapeutic perspectives that representing an alternative to neural stem cell therapeutic strategies for ameliorating the pathologic consequences of a broad range of genetic and acquired insults to the developing, adult, and aging brain. Evolving regenerative strategies for both neurodevelopmental and neurodegenerative diseases will likely involve the targeting of vulnerable regional neural precursor populations during “presymptomatic” clinicopathological stages prior to the occurrence of irrevocable neural cell injury and cell death. Anat Rec (New Anat) 265:142–156, 2001. © 2001 Wiley‐Liss, Inc.     

(Re)organisation of the somatosensory system after early brain lesion: A lateralization index fMRI study

ObjectiveTo evaluate the relationship between neural (re)organization of the somatosensory cortex and impairment of sensory function (2-point discrimination [2PD]) in individuals with unilateral cerebral palsy.MethodsWe included 21 individuals with unilateral cerebral palsy. 2PD thresholds were evaluated on thumb pads, and activation of the somatosensory cortex was recorded by functional MRI (fMRI) during passive movements of the affected hand. A lateralization index (LI) was calculated for the primary sensory (S1) and secondary sensory (S2) cortices and the correlation between the LI and 2PD thresholds was analysed.ResultsWe found a significant negative correlation between the 2PD thresholds and the S2 LI (r = −0.5, one-tailed P-value = 0.01) and a trend towards a negative correlation with the S1 LI (r = −0.4, one-tailed P-value = 0.05).ConclusionHigh levels of activation in the contralesional hemisphere were associated with high levels of sensory impairment in individuals with unilateral cerebral palsy. The interhemispheric (re)organization of the somatosensory system may not effectively compensate for somatosensory impairment.