Hydrocephalus in Tuberculous Meningitis

Hydrocephalus is a frequent complication of tuberculous meningitis. We present the incidence of hydrocephalus in patients diagnosed with tuberculosis of the nervous system, the therapeutic possibilities and the evolution of these patients. A consensus definition for tuberculous meningitis (TBM) stratified the cases as definite, probable and possible. In various studies, radiological investigations (CT, MRI) can be normal in the initial stages of the disease in approximately 30% of cases, but they do not exclude the possibility of a TBM. The most common radiological changes found in TBM are communicating hydrocephalus (up to 80% of cases), increased basal contrast (50%), cerebral tuberculomas (30%) and cerebral infarcts (10–40%). MRI has been shown to be more sensitive than a CT scan for diagnosed TBM. Communicating hydrocephalus is among the short-term complications of TBM (approximately 80% of cases), being more frequent than non-communicating ones. In these cases, the need to perform a ventriculo-peritoneal unit must be taken into account. Long-term complications are cognitive impairment, epilepsy, stroke, hydrocephalus, myelitis, damage to the hypothalamus or the pituitary gland manifested by obesity, growth disorders and diabetes insipidus. Sequels may occur frequently in TBM such as dementia, epilepsy, neurological deficits, behavioral disorders, blindness and deafness

Hypothalamic orexin’s role in exacerbated cutaneous vasodilation responses to an anxiogenic stimulus in a surgical menopause model

Distressing symptoms such as hot flashes and sleep disturbances affect over 70% of women approaching menopause for an average of 4-7 years, and recent large cohort studies have shown that anxiety and stress are strongly associated with more severe and persistent hot flashes and can induce hot flashes. Although high estrogen doses alleviate symptoms, extended use increases health risks, and current non-hormonal therapies are marginally better than placebo. The lack of effective non-hormonal treatments is largely due to the limited understanding of the mechanisms that underlie menopausal symptoms. One mechanistic pathway that has not been explored is the wake-promoting orexin neuropeptide system. Orexin is exclusively synthesized in the estrogen receptor rich perifornical hypothalamic region, and has an emerging role in anxiety and thermoregulation. In female rodents, estrogens tonically inhibit expression of orexin, and estrogen replacement normalizes severely elevated central orexin levels in postmenopausal women. Using an ovariectomy menopause model, we demonstrated that an anxiogenic compound elicited exacerbated hot flash-associated increases in tail skin temperature (TST, that is blocked with estrogen), and cellular responses in orexin neurons and efferent targets. Furthermore, systemic administration of centrally active, selective orexin 1 or 2 and dual receptor antagonists attenuated or blocked TST responses, respectively. This included the reformulated Suvorexant, which was recently FDA-approved for treating insomnia. Collectively, our data support the hypothesis that dramatic loss of estrogen tone during menopausal states leads to a hyperactive orexin system that contributes to symptoms such as anxiety, insomnia, and more severe hot flashes. Additionally, orexin receptor antagonists may represent a novel non-hormonal therapy for treating menopausal symptoms, with minimal side effects

Orexin Depolarizes Central Amygdala Neurons via Orexin Receptor 1, Phospholipase C and Sodium-Calcium Exchanger and Modulates Conditioned Fear

Orexins (OX), also known as hypocretins, are excitatory neuropeptides with well-described roles in regulation of wakefulness, arousal, energy homeostasis, and anxiety. An additional and recently recognized role of OX is modulation of fear responses. We studied the OX neurons of the perifornical hypothalamus (PeF) which send projections to the amygdala, a region critical in fear learning and fear expression. Within the amygdala, the highest density of OX-positive fibers was detected in the central nucleus (CeA). The specific mechanisms underlying OX neurotransmission within the CeA were explored utilizing rat brain slice electrophysiology, pharmacology, and chemogenetic stimulation. We show that OX induces postsynaptic depolarization of medial CeA neurons that is mediated by OX receptor 1 (OXR1) but not OX receptor 2 (OXR2). We further characterized the mechanism of CeA depolarization by OX as phospholipase C (PLC)- and sodium-calcium exchanger (NCX)- dependent. Selective chemogenetic stimulation of OX PeF fibers recapitulated OXR1 dependent depolarization of CeA neurons. We also observed that OXR1 activity modified presynaptic release of glutamate within the CeA. Finally, either systemic or intra-CeA perfusion of OXR1 antagonist reduced the expression of conditioned fear. Together, these data suggest the PeF-CeA orexinergic pathway can modulate conditioned fear through a signal transduction mechanism involving PLC and NCX activity and that selective OXR1 antagonism may be a putative treatment for fear-related disorders

Polarization Control of Wafer-Fused Long-Wavelength VCSELs using Sub-Wavelength Shallow Gratings

Polarization stable, wafer-fused 1310 nm VCSELs employing sub-wavelength shallow gratings on their top DBR and emitting 1.5 mW single mode output power in the 20 degrees C - 75 degrees C temperature range are demonstrated. (C) 2008 Optical Society of Americ

2-mu m WAVELENGTH RANGE InGa(Al)As/InP-AlGaAs/GaAs WAFER FUSED VCSELs for SPECTROSCOPIC APPLICATIONS

We demonstrate 2-mu m wavelength, wafer-fused InGa(Al)As/InP-AlGaAs/GaAs vertical-cavity surface-emitting lasers (VCSELs) emitting single-mode power of 0.5 mW at room-temperature with a threshold current of 4mA and side-mode suppression ratio of over 30 dB. Emission wavelength can be continuously tuned with current by similar to 5 nm without mode hopping with a tuning rate of 0.31 nm/mA. These features demonstrate the long wavelength VCSELs potential for gas sensing and other optical spectroscopy applications

Wafer-fused heterostructures : application to vertical cavity surface-emitting lasers emitting in the 1310 nm band

Currently, wafer-fusion technology represents an effective technique for enhancing the performance of long-wavelength vertical cavity surface-emitting lasers (VCSELs) based on classical double heterostructures with multi-quantum well active regions. Using the example of 1310 nm wavelength VCSELs, we demonstrate the status of this technology for wafer-level scale, wavelength-controlled devices with high performance, capable of operation in a wide temperature range up to 90 degrees C with single-mode output power levels in excess of 1 mW and a side mode suppression ratio (SMSR) in excess of 40 dB. No degradation was observed in a qualification lot that operated at 10 mA and 90 degrees C for 2000 h

1.3-mu m Wavelength Coupled VCSEL Arrays Employing Patterned Tunnel Junction

Using tunnel junction patterning and double wafer fusion, we demonstrate phase-locked arrays of VCSELs emitting at the 1300 nm waveband. CW powers as high as 10 mW and coherent beams are demonstrated for various array configurations. (C) 2009 Optical Society of Americ

8 mW fundamental mode output of wafer-fused VCSELs emitting in the 1550-nm band

We report record-high fundamental mode output power of 8 mW at 0 °C and 1.5 mW at 100°C achieved with wafer-fused InAlGaAs-InP/AlGaAs-GaAs 1550 nm VCSELs incorporating a re-grown tunnel junction and un-doped AlGaAs/GaAs distributed Bragg reflectors. A broad wavelength tuning range of 15 nm by current variation and wavelength setting in a spectral range of 40 nm on the same VCSEL wafer are demonstrated as well. This performance positions wafer-fused VCSELs as prime candidates for many applications in low power consumption, “green” photonics

Intra-cavity patterning for mode control in 1.3μm coupled VCSEL arrays

We report coupled VCSEL arrays, emitting at 1.3μm wavelength, in which both the optical gain/loss and refractive index distributions were defined on different vertical layers. The arrays were electrically pumped through a patterned tunnel junction, whereas the array pixels were realized by intra-cavity patterning using sub-wavelength air gaps. Stable oscillations in coupled modes were evidenced for 2x2 array structures, from threshold current up to thermal roll-over, using spectrally resolved field pattern analysi