Ariel Barreto Nogueira

Existence of a potential neurogenic system in the adult human brain

BackgroundPrevailingly, adult mammalian neurogenesis is thought to occur in discrete, separate locations known as neurogenic niches that are best characterized in the subgranular zone (SGZ) of the dentate gyrus and in the subventricular zone (SVZ). The existence of adult human neurogenic niches is controversial.MethodsThe existence of neurogenic niches was investigated with neurogenesis marker immunostaining in histologically normal human brains obtained from autopsies. Twenty-eight adult temporal lobes, specimens from limbic structures and the hypothalamus of one newborn and one adult were examined.ResultsThe neural stem cell marker nestin stained circumventricular organ cells and the immature neuronal marker doublecortin (DCX) stained hypothalamic and limbic structures adjacent to circumventricular organs; both markers stained a continuous structure running from the hypothalamus to the hippocampus. The cell proliferation marker Ki-67 was detected predominately in structures that form the septo-hypothalamic continuum. Nestin-expressing cells were located in the fimbria-fornix at the insertion of the choroid plexus; ependymal cells in this structure expressed the putative neural stem cell marker CD133. From the choroidal fissure in the temporal lobe, a nestin-positive cell layer spread throughout the SVZ and subpial zone. In the subpial zone, a branch of this layer reached the hippocampal sulcus and ended in the SGZ (principally in the newborn) and in the subiculum (principally in the adults). Another branch of the nestin-positive cell layer in the subpial zone returned to the optic chiasm. DCX staining was detected in the periventricular and middle hypothalamus and more densely from the mammillary body to the subiculum through the fimbria-fornix, thus running through the principal neuronal pathway from the hippocampus to the hypothalamus. The column of the fornix forms part of this pathway and appears to coincide with the zone previously identified as the human rostral migratory stream. Partial co-labeling with DCX and the neuronal marker βIII-tubulin was also observed.ConclusionsCollectively, these findings suggest the existence of an adult human neurogenic system that rises from the circumventricular organs and follows, at minimum, the circuitry of the hypothalamus and limbic system.

Multimodality monitoring, inflammation, and neuroregeneration in subarachnoid hemorrhage.

BACKGROUND: Stroke, including subarachnoid hemorrhage (SAH), is one of the leading causes of morbidity and mortality worldwide. The mortality rate of poor-grade SAH ranges from 34% to 52%. In an attempt to improve SAH outcomes, clinical research on multimodality monitoring has been performed, as has basic science research on inflammation and neuroregeneration (which can occur due to injury-induced neurogenesis). Nevertheless, the current literature does not focus on the integrated study of these fields. Multimodality monitoring corresponds to physiological data obtained during clinical management by both noninvasive and invasive methods. Regarding inflammation and neuroregeneration, evidence suggests that, in all types of stroke, a proinflammatory phase and an anti-inflammatory phase occur consecutively; these phases affect neurogenesis, which is also influenced by other pathophysiological features of stroke, such as ischemia, seizures, and spreading depression. OBJECTIVE: To assess whether injury-induced neurogenesis is a prognostic factor in poor-grade SAH that can be monitored and modulated. METHODS: We propose a protocol for multimodality monitoring-guided hypothermia in poor-grade SAH in which cellular and molecular markers of inflammation and neuroregeneration can be monitored in parallel with clinical and multimodal data. EXPECTED OUTCOMES: This study may reveal correlations between markers of inflammation and neurogenesis in blood and cerebrospinal fluid, based on clinical and multimodality monitoring parameters. DISCUSSION: This protocol has the potential to lead to new therapies for acute, diffuse, and severe brain diseases. ABBREVIATIONS: BBB, blood-brain barrier CPP, cerebral perfusion pressure EEG, electroencephalography ICP, intracranial pressure IL, interleukin MCA, middle cerebral artery SAH, subarachnoid hemorrhage SD, spreading depression SGZ, subgranular zone SVZ, subventricular zone TCD, transcranial Doppler

Letter: Extensive Migration of Young Neurons Into the Infant Human Frontal Lobe

To the Editor: Paredes et al1,2 showed, in a manuscript published recently in Science, that human postnatal neurogenesis occurs in noncanonical niches in the frontal lobe and that immature interneurons migrate long distances even in the postmortem brain. These immature interneurons are likely to be postmitotic neurons born principally in the medial ganglionic eminence (MGE; Figure A).1,3,4 The MGE is a fetal brain structure located anterosuperior to the hypothalamus that vanishes after birth.5 An elusive connection with this process of postnatal neurogenesis involves neurons that potentially arise after birth from the structures without blood–brain barrier (ie, the circumventricular organs, located principally in the hypothalamus) and follow through the neural circuits sustained by basal membrane in the ependyma, pia mater, and blood vessels.6 This connection comprehends only anatomical locations where neurogenesis markers are expressed. Nonetheless, this knowledge may serve as a starting point to overcome the differences observed in the studies discussed here and to develop methods aiming at neuroregeneration. The boundaries of the zones analyzed by Paredes et al1,2 and Nogueira et al6 overlap (Figure). First, putative neural stem cells and immature neurons follow through the mammillothalamic tract (figures 9A-9C and 10D-10F in Nogueira et al6) to the anterior nuclei of the thalamus (figure A in Paredes et al2 and figure 6 in Paredes et al1) and next to the anterior cingulate gyrus (figure 3 in Paredes et al;1 Figure B this letter). Second, putative neural stem cells and immature neurons arise from the choroid plexus, which is a circumventricular organ, follow through the fornix (figures 23-25 in Nogueira et al6) to the location referred to as Arc (figure 1 in Paredes et al1), and reach principally the sulci of the cingulate gyrus (figures 3 and S1G in Paredes et al;1 Figure C this letter). Finally, the septal nuclei and anterior hypothalamus (figures 12-15 in Nogueira et al6)—including the organum vasculosum laminae terminalis, another circumventricular organ6— express neurogenesis markers and are adjacent to basal forebrain nuclei at the ventral and anterior portion of the lateral ventricle7 that display dense expression of DCX, an immature neuron marker (figures 1A-1B and S5C in Paredes et al;1 Figure B this letter). The boundary between the septal nuclei and the anterior hypothalamus, including the preoptic area, is the location that could be explored to assess the major caveat in the comparison described here. The caveat is that Paredes et al1,2 practically did not find immature neurons after infancy, and Nogueira et al6,8 found expression of neurogenesis markers in the circumventricular organs and adjacent structures of the adult human brain. Moreover, Paredes et al1,2 showed DCX expression in interneurons, and Nogueira et al6 showed DCX expression in neuronal fibers with long projections. One might speculate that this difference occurs because the MGE vanishes after birth and the formation of interneurons that migrate postnatally ceases, but the neurogenesis from the circumventricular organs to the counterpart location of the MGE in the postnatal brain (Figure A) persists. The organotypic culture of postmortem human brain developed by Paredes et al1 is a novel method that can be used to assess adult neurogenesis in the hypothalamus. The fetal hypothalamus contributes to the migration of MGE-produced interneurons because it forms an inhibitory environment for this migration that contrasts with the permissive environment formed by cortical areas.3 If adult neurogenesis is revealed in the human hypothalamus, perhaps its stimulation could recapitulate the interaction between the hypothalamus and MGE and trigger neurogenesis from the counterpart location of the MGE in adults (Figure A). This would be an approach to pursue treatment for neuropsychiatric conditions that involve interneurons such as epilepsy, schizophrenia, and autism.9,10

Letter: Human Hippocampal Neurogenesis Drops Sharply in Children to Undetectable Levels in Adults

To the Editor: Previous studies have concluded that the adult human temporal lobe displays neurogenesis,1 but a manuscript published recently in Nature by Sorrells et al2 showed evidence that the subgranular zone (SGZ) of the dentate gyrus is not a primary neurogenic niche in humans, contrary to what is observed in other mammals. Part of the explanation for this apparent contradiction is that in the adult human temporal lobe neurogenesis may occur mostly in the subiculum,3 which is located at a boundary of the hippocampal formation.4,5 Sorrells et al2 showed that the expression of neurogenesisrelated markers in the SGZ takes place during early infancy, but vanishes in a few years. We have previously shown a similar pattern with newborn and adult samples (Figure 1), but Sorrells et al2 were able to characterize the dynamics of this shift analyzing a large number of specimens with different ages. Nonetheless, the most challenging conclusion by Sorrells et al2 is that the concept stating that the SGZ is a primary adult mammalian neurogenic niche does not apply for humans. This conclusion is in a certain degree complemented by our findings indicating that neurogenesis in the adult human hippocampal formation may have shifted in a great percentage from the SGZ to the subiculum3 across the evolutionary tree. We showed that in the human temporal lobe there is a continuous layer of cells expressing neurogenesis-related markers3 (Figures 1A, 2, and 3). This layer begins (Figure 2A) with the choroid plexus ependymal cells, which express the neural stem cell marker CD133 (Figure 2B). Next, we detected the expression of the neural stem cell marker nestin in cells with long processes located at the taenia fimbria (Figure 2C), which represents the attachment of the choroid plexus to the fimbria. This layer continues through the subpial zone of the medial temporal lobe (Figure 2D) and divides into a minor branch ending at the SGZ and a major branch ending at the Cornu Ammonis 1 (CA1) zone (Figures 2E and 2F). The finding of a minor branch of the nestin positive cells ending at the SGZ is midway between the findings of Sorrells et al2 and a recent study showing expression of neurogenesisrelated markers in the adult human SGZ.6 The analysis of the subiculum has not been reported in these 2 studies.2,6 As in the study by Sorrells et al,2 we3 and Crespel et al7 found nestin positive cells in the molecular layers of the hippocampus proper, located superiorly to the granule cell layer of the dentate gyrus (in opposition to the location of the SGZ, inferior to the granule cell layer). Indeed, the molecular layers are located adjacent to the hippocampal fissure, in a zone that is a remnant of the subpial zone of the hippocampal sulcus during fetal development.3-5,7 The major branch of the nestin positive cell layer in the subpial zone of the medial temporal lobe ends up at the CA1 zone and is adjacent to the subiculum, where we found expression of the immature neuron marker doublecortin (DCX) in neuronal cell bodies and processes (Figure 3A). Next, the DCX positive neuronal processes depict the expected projection from the subiculum to the fimbria and the mammillary body in the hypothalamus (Papez circuit; Figures 3B-3D). Accordingly, the trajectory of DCX positive fibers follows medially through the subiculum (contrary to the CA1 direction), displays a curve that runs inferiorly and laterally up to the subventricular zone of the hippocampus proper, and reaches the fimbria (Figures 1A and 3A-3D). Therefore, as in the study by Sorrells et al,2 no DCX (as well as the immature and mature neuron marker βIII-tubulin) was detected in the SGZ or in the granule cell layer (Figures 3E3H), contrary to what was observed regarding the mature neuron marker microtubule-associated protein-2 (Figures 3I and 3J). With the evidence provided by Sorrells et al2 that the SGZ is not a primary neurogenic niche in adult humans, a next step could be searching for evidence of neurogenesis also in zones that were beyond the scope of their study. The subiculum is a candidate in this regard because indications of neurogenesis were observed in samples of the medial temporal lobe,1,3,8 and we found DCX expression in the subiculum.3 Moreover, the subiculum displays a major enlargement from rodents to primates4 and is the structure where the 3-layer cortex becomes the 6-layer cortex.4 Sorrells et al2 concluded that neurogenesis, if any, is minimal in the adult human SGZ. This result is at least partially in disagreement with other reports.1,3,6-8 Our most plausible explanation for this controversy is that, taking into account the adult human hippocampal formation as a whole (ie, the hippocampus proper [CA1-CA4], dentate gyrus, subicular complex, and fimbria), the SGZ is indeed a minor neurogenic niche in comparison to the subiculum. Anyway, the study by Sorrells et al2 shows that adult human neurogenesis is far from being an issue with consensus. Perhaps, it is time to standardize minimal methodological requirements—which include (but are not restricted to) the maximum premortem agonal period, the maximum time elapsed from death to tissue fixation,3 and a demonstration of the location of expression of neurogenesis markers in the brain cytoarchitecture3,9—and organize an open data repository of “human neurogenomics.”

Punched out multiple myeloma lytic lesions in the skull.

under the terms of the Creative Commons Attribution Non-Commercial License which permits unrestricted non-commercial use, distribution, and reproduction in any medium provided article is properly cited. a Anatomic Pathology Department – Faculty of Medicine – University of Sao Paulo, Sao Paulo/SP – Brazil. b Emergency Department – Hospital das Clinicas – Faculty of Medicine – University of Sao Paulo, Sao Paulo/SP – Brazil “Punched out” multiple myeloma lytic lesions in the skull

Hypothesis on the Role of Cryptochromes in Inflammation and Subarachnoid Hemorrhage Outcome

We have recently found that the temperature variability (TV) in the day–night cycle may predict the mean intracranial pressure in the following 24 h (ICP24) in subarachnoid hemorrhage (SAH) patients under multimodality monitoring, sedation, and hypothermia (<35°C). Specifically, we found that ICP24 = 6 (4 − TV) mmHg. TV is the ratio between the coefficient of variation of temperature during the nocturnal and the preceding diurnal periods. This result suggests that the circadian clock reflects brain plasticity mechanisms and its malfunctioning leads to deterioration of the neurologic status. The sleep–wake cycle is absent in these patients and their circadian clock can function properly only by environment light-independent mechanisms. One mechanism involves the circadian clock proteins named cryptochromes (CRYs). CRYs are highly preserved and widespread in the evolutionary tree, are expressed in different cell types in humans [type II CRYs, in two forms: human cryptochrome 1 and 2 (hCRY1 and hCRY2)], and in certain species, respond to blue light and play role in magnetoreception. Interestingly, SAH outcome seems to correlate with inflammation, and CRYs decrease inflammatory activity. Our hypothesis derived from these observations is that CRYs modulate the circadian oscillation of temperature even during therapeutic hypothermia and improve outcome in SAH through decrease in inflammation. A strategy to test this hypothesis is to measure periodically during the acute phase of high-grade SAH the level of CRYs in cerebrospinal fluid (CSF) and circulating white blood cells, and to correlate these levels with outcome, TV, ICP24, and pro- and anti-inflammatory markers in CSF and blood. If this hypothesis is true, the development of therapies targeting inflammation in SAH could take advantage of cryptochrome properties. It has been shown that blue light phototherapy increases the expression of CRYs in blood mononuclear cells in jaundiced neonates. Likewise, visual stimulus with flashing light improves Alzheimer’s disease features in experimental model and there is a prominent expression of CRYs in the retina. Remarkably, recent evidence showed that hCRY2 responds to electromagnetic fields, which could be one elusive mechanism of action of transcranial magnetic stimulation and a reason for its use in SAH.

Hepatocellular carcinoma may display elevated nestin expression in endothelial cells: experimental study

CONTEXT AND OBJECTIVE Nestin, a class VI intermediate filament protein, is highly expressed in the portal mesenchyme and sinusoidal endothelium of the human fetal liver, but scarcely expressed in adult portal vessel endothelium. During experimental liver regeneration, an increased number of nestin-positive parenchymal cells have been observed in the zone adjacent to the Hering canals. These parenchymal cells are regarded as hepatic stem cells or hepatoblasts, which may be involved in hepatocellular carcinogenesis. In the light of recent reports describing nestin-positive parenchymal cells in hepatocellular carcinoma, we aimed to use this tumor type as a positive control for immunohistochemical detection of nestin. DESIGN AND SETTING Experimental study conducted at a university hospital. METHODS Hepatocellular carcinoma sections from one case were analyzed for nestin expression by immunohistochemistry using confocal microscopy. RESULTS Surprisingly, a conspicuous pattern resembling liver sinusoid-like cytoarchitecture was observed upon nestin staining of endothelial cells. CONCLUSIONS This pattern has not been previously described. The preliminary results shown here suggest that nestin-positive endothelial cells are located in niches of immature or proliferative cells. Moreover, nestin expression in endothelial cells of hepatocellular carcinoma enhances the role of angiogenesis in this tumor type, although the prevalence of this immunohistopathological pattern remains to be determined. Finally, hepatocellular carcinoma is an effective positive control for nestin staining in fluorescent immunohistochemistry.

Renal tubular dysgenesis with hypocalvaria and ileocecal valve agenesis: an autopsy report

Renal tubular dysgenesis (RTD) is a rare, lethal, autosomal recessive disorder characterized by non-differentiation of the renal proximal convoluted tubules, resulting in oligohydramnios. It is usually diagnosed in the second trimester of pregnancy, following the oligohydramnios sequence, pulmonary hypoplasia and hypocalvaria. The prognosis is poor, and death usually occurs in utero or within the first few days of life. The pathogenesis of RTD is associated with the perinatal use of drugs, such as angiotensin- converting enzyme inhibitors, angiotensin II receptor antagonists, and anti- inflammatory drugs, as well as with fetal transfusion syndrome, genetic mutations in the pathway of the renin-angiotensin system pathway, cocaine snorting, or other pathological mechanisms that reduce renal blood flow. Here, we report the autopsy of a neonate born to consanguineous parents at 38 weeks of gestation, with RTD, decreased amniotic fluid, oligohydramnios sequence, hypocalvaria, pulmonary hypoplasia, and ileocecal valve agenesis. To our knowledge, the latter has never been reported associated with RTD.

Two consecutive intrauterine pregnancies following transperitoneal ovum migration

CONTEXT Transperitoneal migration is a mechanism for oocyte retrieval that is generally demonstrated in certain cases of ectopic pregnancy. However, the association between these two conditions is debatable. The rare occasions on which intrauterine pregnancy following transperitoneal migration can be documented are an opportunity for studying this topic. CASE REPORT We report the case of a female with a history of salpingectomy due to an ectopic pregnancy at 31 years of age. Two subsequent pregnancies were intrauterine. In both of them, ultrasound revealed that the corpus luteum was located in the ovary ipsilateral to the salpingectomy. CONCLUSION To our knowledge, this is the first reported case of two intrauterine pregnancies following transperitoneal migration, carried to term, and resulting in the delivery of two healthy children. The clinical and physiological implications are discussed.