Early Clinical and Subclinical Visual Evoked Potential and Humphrey's Visual Field Defects in Cryptococcal Meningitis.

Cryptococcal induced visual loss is a devastating complication in survivors of cryptococcal meningitis (CM). Early detection is paramount in prevention and treatment. Subclinical optic nerve dysfunction in CM has not hitherto been investigated by electrophysiological means. We undertook a prospective study on 90 HIV sero-positive patients with culture confirmed CM. Seventy-four patients underwent visual evoked potential (VEP) testing and 47 patients underwent Humphrey's visual field (HVF) testing. Decreased best corrected visual acuity (BCVA) was detected in 46.5% of patients. VEP was abnormal in 51/74 (68.9%) right eyes and 50/74 (67.6%) left eyes. VEP P100 latency was the main abnormality with mean latency values of 118.9 (±16.5) ms and 119.8 (±15.7) ms for the right and left eyes respectively, mildly prolonged when compared to our laboratory references of 104 (±10) ms (p<0.001). Subclinical VEP abnormality was detected in 56.5% of normal eyes and constituted mostly latency abnormality. VEP amplitude was also significantly reduced in this cohort but minimally so in the visually unimpaired. HVF was abnormal in 36/47 (76.6%) right eyes and 32/45 (71.1%) left eyes. The predominant field defect was peripheral constriction with an enlarged blind spot suggesting the greater impact by raised intracranial pressure over that of optic neuritis. Whether this was due to papilloedema or a compartment syndrome is open to further investigation. Subclinical HVF abnormalities were minimal and therefore a poor screening test for early optic nerve dysfunction. However, early optic nerve dysfunction can be detected by testing of VEP P100 latency, which may precede the onset of visual loss in CM

Cryptococcal Neuroradiological Lesions Correlate with Severity during Cryptococcal Meningoencephalitis in HIV-Positive Patients in the HAART Era

Cryptococcal meningoencephalitis has an overall global mortality rate of 20% in AIDS patients despite antifungals. There is a need for additional means of precise assessment of disease severity. We thus studied the radiological brain images available from 62 HIV-positive patients with cryptococcocal meningoencephalitis to analyse the brain lesions associated with cryptococcosis in relationship with disease severity, and the respective diagnostic contribution of magnetic resonance (MR) versus computed tomography (CT)

High pressure synchrotron X-ray diffraction studies of biological molecules using the diamond anvil technique

A system for high pressure synchrotron X-ray diffraction studies of biological samples in a diamond anvil cell (DAC) is described. It is capable of operating in the whole temperature and pressure range of interest for studies of biological molecules, i.e., in the temperature range from −40 to 100°C at pressures between 1 bar and 50 kbar. The pressure is calibrated by measuring the pressure dependence of the ruby fluorescence line at 694 nm. Two linear detectors connected in series are used to measure simultaneously the small- and wide-angle X-ray scattering. The advantage of the experimental technique is threefold: Firstly, the amount of sample can be kept to a minimum (ca. 30 nl) using the high intensity of synchrotron radiation. Secondly, only the diamond anvil technique allows to reach extreme pressures. Thirdly, the use of the dual detector system allows recording of diffraction data both in the small- and wide-angle region at the same time. Examples of hitherto unknown phases of aqueous lipid and protein samples illustrate the potential of the system

Increased neuropeptide Y-like immunoreactivity in cerebrospinal fluid and plasma of human immunodeficiency virus-infected patients: relationship to HIV encephalopathy

Neuropeptide Y (NPY) is one of the most abundant and phylogenetically best conserved peptides in the mammalian central and peripheral nervous system where it plays an important role in the regulation of cardiovascular, metabolic, endocrine, immunological and cognitive functions. In a prospective study we determined neuropeptide Y-like immunoreactivity (NPY-LI) in cerebrospinal fluid (CSF) and plasma of 95 HIV-seropositive (n = 49) or seronegative (n = 46) patients who underwent diagnostic CSF examination. CSF and plasma NPY-LI but not noradrenaline concentrations were higher in seropositive than in seronegative patients indicating that raised levels of NPY-LI did not result from a non-specific activation of the sympathetic nervous system. Increased CSF NPY-LI was positively correlated with the degree of HIV encephalopathy (P <0.01, Kruskal-Wallis test). Inflammatory disorders of the central nervous system and dementia due to other causes in HIV-seronegative patients were not associated with increased CSF NPY-LI. Our data suggest that increased CSF NPY-LI is a relatively specific phenomenon of HIV encephalopathy and may be involved in the pathogenesis of HIV-related neurological dysfunction. The links between retroviral infection and increased expression of neuropeptide Y and their pathophysiological implications remain to be determine