Hox genes are evolutionarily conserved transcription factors which act to control important developmental pathways involved in morphogenesis of the embryo. Hoxa2 is expressed in the developing CNS in rhombomeres 2-7 in the presumptive hindbrain. During development Hoxa2 expression extends caudally throughout the spinal cord and persists into adulthood.</p><p> Although previous analysis of Hoxa2 expression indicates its possible role in neuronal circuit specification and/or dorsal-ventral patterning within the spinal cord, the precise genetic pathways through which Hoxa2 affects spinal cord development have not been characterized. We have used immunoprecipitation of Hoxa2-target DNA complexes from chromatin preparations of E18 mouse spinal cord and hindbrain tissue to isolate in vivo downstream target genes of Hoxa2. Seven DNA fragments were isolated, sequenced and were shown to exhibit in vitro DNA binding by Hoxa2. A search of sequence databases for the target sequences revealed that of these, two displayed high identity with novel mouse genes: toll-associated serine protease (Tasp) and the murine homolog of the human dual specificity tyrosine phosphorylation regulated kinase 4 (Dyrk4). Also, two of the isolated clones are presumably bacterial sequences containing the canonical homeodomain binding site TAAT, and the remaining three clones have not yet been mapped in the mouse genome. A potential core Hoxa2 binding motif consisting of 5' CCATCA/T 3', which is based on a previously characterized Hoxa2-Pbx consensus sequence (Lampe et al., 2004), has been identified in both the Tasp and Dyrk4 intronic elements. Both Dyrk4 and Tasp mRNA have been detected within the developing mouse from E10-18 and in the adult CNS. Analysis by RT-PCR of Tasp expression in Hoxa2-/- newborn mice hindbrain and spinal cord tissues showed an upregulation of Tasp, and transient transfection experiments indicated that Hoxa2 may act as a transcriptional repressor of Tasp through an intronic regulatory element. Transfection studies using the intronic sequence of Dyrk4 indicated that it may function as an enhancer of transcription of Dyrk4 in the presence of Hoxa2. Both Dyrk4 and Tasp belong to large protein subfamilies whose members play a role in numerous developmental pathways in several organisms. Tasp, also known as HtrA3, interacts with TGFâ signaling molecules which are known to be key regulators of development, dorsoventral patterning and are involved in various neuronal pathways. Although the function of Dyrk4 is not known, many of its family members are involved in the regulation of transcription factors and signaling molecules via phosphorylation that are involved in neuronal pathways also. Hoxa2 may act in specifying neuronal subtypes and dorsoventral patterning in the CNS through down and upregulation of its downstream targets Dyrk4 and Tasp, respectively.

Hox genes are evolutionarily conserved transcription factors which act to control important developmental pathways involved in morphogenesis of the embryo. Hoxa2 is expressed in the developing CNS in rhombomeres 2-7 in the presumptive hindbrain. During development Hoxa2 expression extends caudally throughout the spinal cord and persists into adulthood.</p><p> Although previous analysis of Hoxa2 expression indicates its possible role in neuronal circuit specification and/or dorsal-ventral patterning within the spinal cord, the precise genetic pathways through which Hoxa2 affects spinal cord development have not been characterized. We have used immunoprecipitation of Hoxa2-target DNA complexes from chromatin preparations of E18 mouse spinal cord and hindbrain tissue to isolate in vivo downstream target genes of Hoxa2. Seven DNA fragments were isolated, sequenced and were shown to exhibit in vitro DNA binding by Hoxa2. A search of sequence databases for the target sequences revealed that of these, two displayed high identity with novel mouse genes: toll-associated serine protease (Tasp) and the murine homolog of the human dual specificity tyrosine phosphorylation regulated kinase 4 (Dyrk4). Also, two of the isolated clones are presumably bacterial sequences containing the canonical homeodomain binding site TAAT, and the remaining three clones have not yet been mapped in the mouse genome. A potential core Hoxa2 binding motif consisting of 5' CCATCA/T 3', which is based on a previously characterized Hoxa2-Pbx consensus sequence (Lampe et al., 2004), has been identified in both the Tasp and Dyrk4 intronic elements. Both Dyrk4 and Tasp mRNA have been detected within the developing mouse from E10-18 and in the adult CNS. Analysis by RT-PCR of Tasp expression in Hoxa2-/- newborn mice hindbrain and spinal cord tissues showed an upregulation of Tasp, and transient transfection experiments indicated that Hoxa2 may act as a transcriptional repressor of Tasp through an intronic regulatory element. Transfection studies using the intronic sequence of Dyrk4 indicated that it may function as an enhancer of transcription of Dyrk4 in the presence of Hoxa2. Both Dyrk4 and Tasp belong to large protein subfamilies whose members play a role in numerous developmental pathways in several organisms. Tasp, also known as HtrA3, interacts with TGFâ signaling molecules which are known to be key regulators of development, dorsoventral patterning and are involved in various neuronal pathways. Although the function of Dyrk4 is not known, many of its family members are involved in the regulation of transcription factors and signaling molecules via phosphorylation that are involved in neuronal pathways also. Hoxa2 may act in specifying neuronal subtypes and dorsoventral patterning in the CNS through down and upregulation of its downstream targets Dyrk4 and Tasp, respectively.

No description available.

Despite the prevalence of CNS disorders, treatment options for CNS disorders fall woefully behind treatment options for other systemic disorders. This is due to the presence of the blood brain barrier (BBB) acting as an obstacle, preventing foreign substances from entering the brain. A newly developed and innovative biomedical procedure attempts to bypass the BBB in the delivery of therapeutics by using focused ultrasound (FUS) to disrupt and temporarily open the BBB. The use of FUS-facilitated BBB opening is able to target specific tissue for noninvasive, localized BBB penetration. As the technique is experimental and in it's nascent stage of development, there are only a few studies that investigate its abilities in delivering treatments directly to the brain. The studies involve delivery of large, hydrophilic molecules that traditionally would not be able to bypass the BBB and enter the brain, and analysis of CNS concentrations of the molecules after FUS treatment, as well as the therapeutic successes. Results of FUS the studies are promising and the results demonstrate that the procedure is able to significantly increase drug concentrations in the brain, increase survival rates in animal models, decrease tumor growth, and decrease tumor margins and volume. The potential and power of FUS should be further explored as the future of CNS disorder treatments.

Abstract Imaging of the head and spine with CT and/or MRI was performed on 125 Northern Finnish NF1 patients to evaluate the CNS lesions in patients of different ages and their role in diagnosis and follow-up. Manifestations of NF1 in the head were more common in children than in adults. 77% of the children and 33% of the adults had T2 hyperintense brain lesions. Optic gliomas were present in 29% of the patients, in 44% of the children and 10 % of the adults. 8% of the patients had other intracranial tumours . Spinal lesions were seen in 75% of the patients. Hyperintense T2 lesions were most common in the age group of 5 to 9 years. During follow-up of the children, the lesions diminished in 25%, remained unchanged in 36%, showed mixed behaviour in 20% and disappeared in 10%. In 15% they increased in size and number. In one patient a malignant tumour developed at the site of a T2 lesion. Optic gliomas were located intraorbitally and/or prechiasmally in 94%, chiasmally and/or at the hypothalamus in 58% and in other optic areas in 14% of the patients. 52 % of the intraorbital gliomas were bilateral. The gliomas remained unchanged in 68% of the children and 50% of the adults. Other lesions included plexiform neurofibromas, sphenoid bone dysplasias and hydrops of the optic sheath. Optic glioma was more common in children with T 2 hyperintense brain lesions than without them. The other brain tumours included six astrocytomas, including an affected mother and her son. In one patient the astrocytoma regressed spontaneously. Hydrocephalus was seen in 5% of the patients. T2 hyperintense brain lesions were more common and numerous in macrocephaly; all macrocephalic children, but only 59% of the normocephalic children were affected. All children without T2 lesions were normocephalic. The brain measurements did not reveal any specific area to be responsible for macrocephaly. Spinal postural changes and dural ectasias were more common in adults. The spinal cord was affected in two patients. Spinal neurofibromas were seen in 19% of the children and 55% of the adults. Even young children may have severe manifestations. In one family a rare familial type of spinal neurofibromatosis (FSNF) was observed in four adults with bilateral spinal neurofibromas at all levels of the spine. Although both CT and MRI were valuable in CNS imaging, MRI proved to be the method of choice in detecting T2 hyperintense brain lesions, in evaluating the intracranial extent of optic gliomas and hydrops of the optic sheath and lesions of the spinal cord and nerves. MR imaging proved necessary for evaluating the extent of NF1 manifestations and helpful in the diagnosis, screening and follow-up of NF1 patients.

Fibroblast Growth Factor 21 (FGF21) is a hormone that is produced from the liver which has pleiotropic effects. Physiologically, FGF21 increases energy expenditure, increases glucose uptake, enhances glucose tolerance, and increases peripheral insulin sensitivity. Pharmacologically, FGF21 reverses obesity and diabetes in animal models and significantly improves metabolic profiles in humans through unknown mechanisms. We hypothesized that the physiological actions of FGF21 may provide insights to explain FGF21’s beneficial pharmacological effects. The overall theme of this work was to identify the elusive mechanism by which FGF21 regulates energy homeostasis. In chapter 1, I review some adipokines and hepatokines that regulate energy homeostasis. In chapter 2, I provide background on fibroblast growth factors (FGFs), metabolic FGFs, and the tissue-specific effects of FGF21. In chapter 3, I will review the role of growth factors in thermoregulation. In chapter 4, we use tissue-specific loss of function models to investigate the trajectory of FGF21’s thermogenic effects during prolonged cold. In chapter 5, we specifically address the necessity and sufficiency of FGF21 signaling directly to adipose tissue, and the contribution of the adipokine adiponectin in mediating FGF21’s metabolic effects. In chapter 6, I summarize our results, reflect upon the ramifications of these results, and briefly address potential future experiments given our results on the physiological and pharmacological actions of FGF21 in adipose tissues.

Background: The aim of this study was to describe the morphological signs of the central nervous system lymphoma (CNSL) in magnetic resonance imaging (MRI). We compared morphological characteristics of primary CNSL (PCNSL) and secondary CNSL (SCNSL) and also of PCNSL and glioblastoma (GBM). Methods: We included 64 patients with PCNSL (ten of them were immunocompromised), 21 patients with SCNSL and 54 patients with GBM. The diagnosis was confirmed histologically in all patients. We evaluated morphological signs on the first MRI examination. Additionally, in patients with PCNSL, we evaluated the development of the disease on follow-up examination before histological confirmation of the diagnosis, if available. Results: In most patients with PCNSL (62.5%) the tumor was localized supratentorially and presented as multiple lesions (53.1%) or as a diffuse infiltrative lesion (23.4%). In 87.5% of the patients the lesions reached the brain surface. Infiltration of ependyma was seen in 56.3%, infiltration of meninges in 39.1% and infiltration of cranial nerves in 48.5% of patients. Restriction of diffusion in some part of the tumor was apparent in nearly all patients (97.6%) with PCNSL. After administration of contrast media, marked enhancement was usually seen. In immunocompetent patients, homogenous...

Recent studies have confirmed the presence of insulin receptors in the rat brain although their function has still not been well defined. The present study explores the possibility that insulin receptors in the brain can alter or contribute to central neurotransmission. Insulin caused a dose-dependent inhibition of hippocampal pyramidal neurons. The pattern of inhibition mirrored the binding kinetics of insulin in the hippocampus. Two related peptides, proinsulin and desoctapeptide insulin, had neuronal effects consistent with their binding to insulin receptors in the brain. Proinsulin was effective in doses 30-fold greater than insulin, whereas desoctapeptide insulin had little or no effect. These observations indicate that the inhibitory effect of insulin in this tissue may be insulin receptor-mediated and support a previously suggested functional role of insulin in the central nervous system.

No description available.

Thesis advisor: Kenneth C. Williams / Thesis advisor: Welkin Johnson / Understanding the persistence of viral reservoirs despite durable antiretroviral therapy (ART) is essential to addressing the challenge of viral clearance and chronic immune activation with human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV). It had not previously been demonstrated that HIV or SIV- infected macrophage traffic out of the CNS to reseed the periphery, potentially contributing to viral recrudescence. This thesis proposes the central hypothesis that persistent traffic of monocytes and macrophages out of the CNS and subsequent viral reseeding of the periphery plays a key role in viral dissemination, particularly in the context of acquired immunodeficiency syndrome (AIDS), with ART, and following ART interruption. In Chapter 2, utilizing Superparamagnetic iron oxide nanoparticles (SPION) as a novel in vivo method to label CNS macrophages, we demonstrate that under normal conditions, CNS macrophages migrate out to the deep cervical lymph nodes. However, during SIV infection, we observe an accumulation of macrophages within the CNS and a reduction in traffic out to the periphery. Importantly, with SIV-infection, we found that SIV-infected macrophages traffic out to deep cervical lymph nodes. From these, we find that under normal conditions, macrophages traffic out of the CNS. However, during SIVinfection, macrophages are retained within the CNS, contributing to inflammation in the brain, and those that do migrate out are virally infected. In Chapter 3, we hypothesized that ART restores CNS macrophage traffic and prevents viral dissemination from the CNS reservoir by eliminating the traffic of virally infected macrophage out of the CNS, as seen with AIDS and SIV-induced encephalitis (SIVE). We also hypothesized that following four weeks of ART interruption there would be expansion of the CNS viral reservoir with traffic out of virally infected macrophages to the deep cervical lymph node. Utilizing a rapid AIDS model with CD8 depletion to induce a high incidence of SIVE and intracisternal injection of SPION, we found that SIV-infected macrophages accumulate in the perivascular space, meninges, choroid plexus, and traffic out at a low rate to the deep cervical lymph node, spleen, and even to the dorsal root ganglia (DRG). With ART, we found clearance of virally infected macrophages in the brain perivascular space but not in the meninges or choroid plexus. Importantly following four weeks of ART interruption, the perivascular space remained clear of virus but there was a rebound in the meninges and scattered virally infected macrophages in the choroid plexus. With ART and following a brief ART interruption, there was no traffic of CNS virally infected macrophages out to the deep cervical lymph node, spleen, or DRGs. These data demonstrate that ART effectively clears virus-infected perivascular macrophages and eliminates the traffic of virus-infected macrophages out of the CNS to the deep cervical lymph node and spleen but does not eliminate virally infected macrophages in the meninges or choroid plexus. By using two differently colored SPION injected early and late, we observed an increase in early SPION+ macrophages within and outside the CNS with SIVE, ART, and ART interruption, indicating that SIV-infected perivascular macrophages establish an early viral reservoir with ongoing seeding in the meninges and choroid plexus throughout infection. These findings are consistent with the retention of CNS macrophages in the presence of inflammation and viral infection, as well as the potential for viral rebound in the CNS from sources such as the blood, meninges, and choroid plexus with ART and following ART interruption. In Chapter 4, we propose a novel pathway for virus-infected macrophages to traffic out of the CNS via cranial and spinal nerves. Due to the persistence of virally infected macrophages in the meninges with durable ART and continuity of the CNS meninges with peripheral nerves, we hypothesize that virally infected macrophage traffic out of the CNS via cranial and peripheral nerves with AIDS and SIVE, on ART, and following ART interruption. To test this hypothesis, we tracked SPION+ macrophages by quantifying them at central (spinal cord and cranial nerves) and peripheral sites (dorsal root ganglia, DRG). Similar to our previous findings in the brain, SIV infection increased the numbers of macrophages in the spinal cord and decreased them in peripheral sites. Staining for viral RNA and GP41 identified virus-infected SPION+ macrophages in cranial nerves and DRG, which were significantly reduced but not eliminated by ART. In animals with AIDS, late- and dual-labeled SPION+ macrophages decreased, suggesting reduced macrophage trafficking late in infection. ART appeared to restore traffic, as higher numbers of late- and dual-labeled macrophages were observed, though this reversed to levels seen in AIDS/SIVE upon ART interruption. Our findings reveal a previously understudied pathway that allows CNS macrophage viral reservoirs to reseed virus to the periphery, a process that persists despite ART. In Chapter 5, we performed a literature review to better understand the effects of HIV infection on aging, as age is a primary risk factor for the development of HIV-associated neurocognitive disorders and HIV-associated sensory neuropathy. With ART extending the lifespan of people living with HIV, they now also experience accelerated aging, leading to earlier onset of age-related conditions like cardiovascular disease and neurocognitive disorders. Evidence suggests this is due to chronic immune activation, co-infections, and possibly ART itself. HIV and aging both alter immune cell populations, increasing inflammatory markers and contributing to "inflamm-aging." While ART slows this acceleration, it cannot prevent aging or related comorbidities. This thesis explores the role of macrophage traffic from the CNS and its contribution to the spread of the virus to peripheral tissues. To investigate this, we utilized a novel in vivo labeling method to track CNS macrophages, identify migration out of the CNS, and evaluate how ART and ART interruption influence the traffic of virally infected macrophages to peripheral tissues. Our findings underscore the role of CNS macrophages in the resolution of inflammation by trafficking out of the CNS, viral rebound from blood- derived sources following ART interruption, and the role of perineural pathways in viral dissemination even with durable ART. / Thesis (PhD) — Boston College, 2024. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Biology.