Cerebrospinal fluid HIV RNA in persons living with HIV.

OBJECTIVES: Despite adequate suppression of plasma HIV RNA, viral escape in cerebrospinal fluid (CSF) is widely reported. Rates of CSF HIV RNA escape vary in the literature. In persons living with HIV (PLWH) undergoing lumbar puncture examination for clinical reasons, we assessed rates of CSF HIV RNA escape. METHODS: Persons living with HIV attending a designated HIV neurology service undergoing CSF assessment for clinical reasons between January 2015 and April 2017 were included in the study. CSF HIV RNA escape was defined as HIV RNA ≥ 0.5 log10 HIV-1 RNA copies/mL higher than plasma HIV RNA or detectable CSF HIV RNA when plasma HIV RNA was < 20 copies/mL. Clinical factors associated with CSF HIV RNA were assessed using logistic regression modelling. RESULTS: Of 38 individuals, 35 were receiving antiretroviral therapy, 30 were male and their mean age was 51 years. Clinical reasons for CSF assessment included investigation for cognitive decline (n = 25), early syphilis (n = 4) and other central nervous system (CNS) conditions (n = 9). HIV RNA was detectable in plasma and CSF in seven and six individuals, respectively, with two individuals (5.3%) meeting the definition of CSF escape. Detectable CSF HIV RNA was associated with a detectable plasma HIV RNA (P < 0.001) and a history of known antiretroviral drug resistance mutations (P = 0.021). CONCLUSIONS: The prevalence of CSF viral escape in PLWH undergoing lumbar puncture examination for clinical reasons is lower than previously reported.

Cerebellar volumes in newly diagnosed and chronic epilepsy.

Cerebellar atrophy is assumed to be a common finding in patients suffering from epilepsy. Anticonvulsants as well as seizure activity itself have been considered to be responsible for it but many studies have addressed these questions in specialised centres for epilepsy thus having a referral bias towards patients with severe epileptic syndromes. The purpose of this study was: 1. To develop a quantitative method on 3D-MRI data to achieve volume or planimetric measurements (of cerebrum, cerebellum and cerebellar substructures). 2. To investigate the prevalence of cerebellar atrophy (and substructure atrophy) in a prospectively investigated population-based cohort of patients with newly diagnosed and chronic epilepsy. 3. To quantify cerebellar atrophy in clinic-based patients, who had had atrophy previously diagnosed on routine visual MRI assessment. 4. To correlate the measures of atrophy with clinical features in both patient groups. A total of 57 patients with either newly diagnosed or chronic active epilepsy and 36 control subjects were investigated with a newly developed semiautomated method for cerebral as well as cerebellar volume measurements and substructure planimetry, corrected for intracranial volume. We did not find any significant atrophy in the population-based cohort of patients with newly diagnosed epilepsy or with chronic epilepsy. Visually diagnosed cerebellar atrophy was mostly confirmed and quantified by volumetric analysis. The clinical data suggested a correlation between cerebellar atrophy and the duration of the seizure disorder and also the total number of lifetime seizures experienced and the frequency of generalised tonic-clonic seizures per year. Volumetry on 3D-MRI yields reliable quantitative data which shows that cerebellar atrophy might be common in severe and/or longstanding epilepsy but not necessarily in unselected patient groups. The results do not support the proposition that cerebellar atrophy is a predisposing factor for epilepsy but rather are consistent with the view that cerebellar atrophy is the aftermath of epileptic seizures or anticonvulsant medication.

An age-related decline in melatonin secretion is not altered by food restriction.

Melatonin has been found to exhibit youth-maintaining and disease-preventing properties. The current study examined whether the age-retarding regimen of chronic food restriction (FR) slowed the decline in melatonin secretion reported to occur with age. Total nocturnal melatonin secretion was assessed by radioimmunoassay of the primary metabolite, 6-sulphatoxymelatonin (6-S-OH-MLT), in urine. Measurements were made through adulthood (70 to 765 days) on male Wistar rats maintained on the FR regimen (60% of the normal intake) with the control animals fed ad libitum (AL). The data of animals exhibiting gross pathology were excluded. Analyses of covariance found the FR regimen had no effect on either the levels or pattern of decline observed in 6-S-OH-MLT excretion through adulthood. However, the FR body-weight-indexed metabolite measures were approximately double those of the AL (p = .06). The possibility that this result may reflect unusually high melatonin peaks in the FR tissues is discussed.

Bicuculline, pentobarbital and diazepam modulate spontaneous GABA(A) channels in rat hippocampal neurons.

Spontaneously opening, chloride-selective channels that showed outward rectification were recorded in ripped-off patches from rat cultured hippocampal neurons and in cell-attached patches from rat hippocampal CA1 pyramidal neurons in slices. In both preparations, channels had multiple conductance states and the most common single-channel conductance varied. In the outside-out patches it ranged from 12 to 70 pS (Vp=40 mV) whereas in the cell-attached patches it ranged from 56 to 85 pS (-Vp=80 mV). Application of GABA to a patch showing spontaneous channel activity evoked a rapid, synchronous activation of channels. During prolonged exposure to either 5 or 100 microM GABA, the open probability of channels decreased. Application of GABA appeared to have no immediate effect on single-channel conductance. Exposure of the patches to 100 microM bicuculline caused a gradual decrease on the single-channel conductance of the spontaneous channels. The time for complete inhibition to take place was slower in the outside-out than in the cell-attached patches. Application of 100 microM pentobarbital or 1 microM diazepam caused 2 - 4 fold increase in the maximum channel conductance of low conductance (<40 pS) spontaneously active channels. The observation of spontaneously opening GABA(A) channels in cell-attached patches on neurons in slices suggests that they may have a role in neurons in vivo and could be an important site of action for some drugs such as benzodiazepines, barbiturates and general anaesthetics.

Spontaneously opening GABA(A) channels in CA1 pyramidal neurones of rat hippocampus.

Spontaneous, single channel, chloride currents were recorded in 48% of cell-attached patches on neurones in the CA1 region of rat hippocampal slices. In some patches, there was more than 1 channel active. They showed outward rectification: both channel conductance and open probability were greater at depolarized than at hyperpolarized potentials. Channels activated by gamma-aminobutyric acid (GABA) in silent patches on the same neurones had similar conductance and outward rectification. The spontaneous currents were inhibited by bicuculline and potentiated by diazepam. It was concluded that the spontaneously opening channels were constitutively active, nonsynaptic GABA(A) channels. Such spontaneously opening GABA(A) channels may provide a tonic inhibitory mechanism in these cells and perhaps in other cells that have GABA(A) receptors although not having a GABA(A) synaptic input. They may also be a target for clinically useful drugs such as the benzodiazepines.

Classification of the epilepsies: time for a change? A critical review of the International Classification of the Epilepsies and Epileptic Syndromes (ICEES) and its usefulness in clinical practice and epidemiological studies of epilepsy.

The Commission on Classification and Terminology of the International League against Epilepsy (ILAE) first devised a comprehensive classification for the epilepsies and epileptic syndromes nearly 30 years ago. Despite subsequent revisions, the classification remains too complicated to be of utility in clinical practice and epidemiological research. Recent developments in neuro-imaging and neurogenetics have also contributed to the limited usefulness of the current International Classification of the Epilepsies and Epileptic Syndromes (ICEES). This review examines the evolution, advantages, and notable disadvantages of the ICEES and assesses its previous application in several population-based studies of epilepsy. The important need for a new, simplified, and aetiologically orientated classification which is amenable to use outside of the tertiary epilepsy centre is discussed.

A threonine residue in the M2 region of the beta1 subunit is needed for expression of functional alpha1beta1 GABA(A) receptors.

Although there is a high degree of homology in the M2 transmembrane segments of alpha1 and beta1 subunits, subunit-specific effects were observed in alpha1beta1 GABA(A) receptors expressed in Spodoptera frugipedra (Sf9) cells when the conserved 13' threonine residue in the M2 transmembrane region was mutated to alanine. When threonine 263 (13') was mutated to alanine in the beta1 subunit, high-affinity muscimol binding and the response to GABA were abolished. This did not occur when the threonine 263 (13') was mutated to alanine in the alpha1 subunit, but the rate of desensitisation increased and the effect of bicuculline, a competitive inhibitor, was reduced. The results show differential effects of subunits on receptor function and support a role for M2 in desensitisation.

Male monozygotic twins discordant for periventricular nodular heterotopia and epilepsy.

PURPOSE: To determine zygosity and study cerebral structure in apparently identical twins with discordant manifestation of focal epilepsy. METHODS: Male twins in their fifth decade were scanned by using magnetic resonance imaging (MRI) to detect structural abnormalities. Zygosity was determined by using 10 microsatellite markers. RESULTS: DNA analysis showed that the twins were >99.99% likely to be monozygous; they were discordant for bilateral symmetric periventricular nodular heterotopia (PNH) and epilepsy. CONCLUSIONS: The discordant occurrence of PNH and epilepsy in monozygotic male twins carries implications with respect to somatic mosaicism, currently held to be responsible for PNH in affected male subjects.

Evidence for nodular epileptogenicity and gender differences in periventricular nodular heterotopia.

OBJECTIVE: To determine whether clinical differences between the sexes seen in periventricular nodular heterotopia (PNH) have structural correlates on imaging. BACKGROUND: PNH is the most common dysgenesis associated with hippocampal sclerosis (HS). Women with PNH have normal intellect; men may have mental retardation and other changes. Familial PNH, seen in women, is linked to Xq28-a region also abnormal in a sporadic male infant with PNH and retardation-suggesting sexual differences in gene expression. Epilepsy associated with PNH may be refractory to drugs, and surgery for associated HS does not stop seizures, suggesting intrinsic epileptogenicity of PNH. METHODS: Quantitative MRI analysis was performed using established techniques for detecting subtle structural changes in 13 female patients (11 sporadic and two familial) and four male patients (sporadic). RESULTS: There is structural heterogeneity in PNH, even in patients with bilateral PNH. On MRI, men have more cerebral abnormalities beyond PNH than control subjects or female patients (p < 0.005). CONCLUSIONS: The findings support the concept of intrinsic epileptogenicity of PNH. There may be additional structural abnormalities relevant to seizure generation, especially in men. Structural heterogeneity, and widespread abnormalities, may need consideration when patients are referred for surgical treatment or when additional studies of patients with PNH are conducted.

A descriptive survey of long-term residents with epilepsy and intellectual disability at the Chalfont Centre: is there a relationship between maladaptive behaviour and magnetic resonance imaging findings?

The advent of high-resolution magnetic resonance imaging (MRI) has facilitated the identification of subtle, aetiologically relevant structural brain abnormalities in a significant proportion of patients with epilepsy and negative standard neuro-imaging. In the present study of people with intellectual disability (ID), the authors show that a high frequency of cerebral structural abnormalities (72.4%) can be demonstrated by high-resolution MRI in patients with epilepsy and ID. Malformations of cortical development (MCD) were found in 8.7% of people without profound ID. An earlier age of onset of habitual seizures was associated with more severe ID and more severe seizures in adulthood. There was no obvious association between this finding and maladaptive behaviour, but a past history of febrile convulsions was associated with increased irritability and agitation. Since there was no obvious association between a history of febrile convulsions and MRI abnormalities, the reason for the above finding remains unclear. Inevitably, any residential epilepsy centre population is subject to selection biases. The population studied was highly skewed, with only one-third of the sample being female and 80% having mild ID. Thus, the findings of the present study cannot necessarily be generalized to all people with ID.

Magnetic resonance imaging in epilepsy with a fast FLAIR sequence.

OBJECTIVE: To assess the diagnostic value of the fast FLAIR sequence in patients with epilepsy. METHODS: One hundred and twenty eight patients with epilepsy and 10 control subjects were scanned with the fast FLAIR sequence with 5 mm slices, a coronal gradient echo (GRE) T1 weighted sequence with 1.5 mm slices and spin echo (SE) or fast spin echo (FSE) proton density and T2 weighted sequences with 5 mm slices. All images were compared by an unblinded neuroradiologist and neurologist. Fast FLAIR images of patients with hippocampal sclerosis (HS) and normal control subjects were also evaluated by two blinded independent raters. RESULTS: Fast FLAIR provided a high conspicuity of neocortical damage, hamartomas, dysembryoplastic neuroepithelial tumours, and clear cut hippocampal sclerosis. However, the same information could be obtained from the coronal T1 and T2 weighted images. In three patients fast FLAIR showed a clearly abnormal signal when SE T2 weighted images had not been definitely abnormal. Heterotopia was less conspicuous on fast FLAIR than GRE T1 weighted images. The two blinded raters detected all but one of the patients with clear cut hippocampal sclerosis on fast FLAIR images but missed all borderline cases of hippocampal atrophy and there were two false positives. Clear cut hippocampal sclerosis was more conspicuous on fast FLAIR images than on SE T2 weighted images in most patients, but additional patients were not identified. CONCLUSION: Fast FLAIR has the advantage of identifying neocortical lesions and definite hippocampal sclerosis with a short scanning time and may also demonstrate lesions when other sequences are normal in a limited number of cases. The technique was not useful, however, for identifying mild hippocampal sclerosis or heterotopia.

Morphometric analysis of gastrocnemius muscle fiber size and fiber proportions in the hypophysectomized rat after prolonged administration of growth hormone or thyroxine.

This study investigated the effects of either growth hormone or thyroxine on muscle fiber atrophy caused by hypophysectomy in male Wistar rats. Muscle fiber size is reported as equivalent circle diameter (ECD) in transverse section of fresh-frozen gastrocnemius muscle. Three months post-hypophysectomy type 1 (slow twitch) and type 2 (fast twitch) muscle fibers were smaller (p < 0.01) than those in intact controls as shown previously in this laboratory. The administration of human growth hormone (GH) (50mIU/100g body weight/day) to hypophysectomized (hypox) rats for 42 days, stimulated body growth, restored 42% of the lost gastrocnemius muscle weight (p < 0.05) and 36% of the lost type 1 fiber size, (p < 0.01), but had no effect on type 2 fiber size. Treatment of hypox rats with physiological doses of thyroxine (5 micrograms T4/100g body weight/alternate day) for 42 days did not affect body growth, gastrocnemius muscle weight or type 1 fiber size, but reduced the size of type 2 fibers (p < 0.01). Thyroxine prevented the decline in the percentage of type 2 fibers which occurs after hypophysectomy. This unique observation suggests that thyroid hormone regulates the proportion of different fiber types in the gastrocnemius muscle. Thus, in hypox rats, GH promoted growth of type 1 or slow twitch muscle fibers needed to support the increasing weight of the growing body. Physiological doses of T4 did not stimulate growth, but caused further atrophy of of type 2 fibers possibly while providing fuel for rapid movement.

The effect of neonatal pinealectomy on the inhibitory actions of food restriction on vaginal opening and collagen aging in the rat.

Long-term food restriction is known to inhibit development and aging in the rat. These actions may be mediated by the pineal hormone, melatonin, whose secretion is increased by food restriction. This mechanism was investigated by studying the effects of pinealectomy in ad libitum fed and food restricted rats of both sexes living under normal conditions of temperature (23 degrees C) and lighting 12 h light:12 h dark cycle) over a period of 400 days. Pinealectomies were performed at the age of 5 days. Pinealectomy did not affect the amount of food eaten per day. Vaginal opening occurred at age 35 days in ad libitum fed female rats and was delayed to 49 days (P < 0.001) in rats whose food intake was restricted by 35%, but only to 41 days (P < 0.001) if food restricted (FR) rats were pinealectomized (Px). The inhibitory effect of food restriction on body growth and tail tendon collagen fibre aging was the same in both intact and pinealectomized rats. At the conclusion of the study in middle age at 400 days, plasma melatonin levels 4 h into the dark cycle were higher in food restricted than in ad libitum fed rats (P = 0.015). This study provides evidence for a role of the pineal in mediating the inhibitory action of food restriction on vaginal opening, but not on body growth or collagen aging in tail tendon up to middle age.

Characteristics of GABAA channels in rat dentate gyrus.

Single channel currents were activated by GABA (0.5 to 5 microM) in cell-attached and inside-out patches from cells in the dentate gyrus of rat hippocampal slices. The currents reversed at the chloride equilibrium potential and were blocked by bicuculline (100 microM). Several different kinds of channel were seen: high conductance and low conductance, rectifying and "nonrectifying." Channels had multiple conductance states. The open probability (Po) of channels was greater at depolarized than at hyperpolarized potentials and the relationship between Po and potential could be fitted with a Boltzmann equation with equivalent valency (z) of 1. The combination of outward rectification and potential-dependent open probability gave very little chloride current at hyperpolarized potentials but steeply increasing current with depolarization, useful properties for a tonic inhibitory mechanism.