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Biomedical subjects

M Habib

Publications and source records attributed to M Habib.

126 records · Page 7Linked to original sources
PubMedDate not supplied

[Neurologic sequelae of the neuroleptics-lithium combination: role of hyperthermia].

The combination of lithium carbonate and neuroleptic is frequently used in the treatment of bipolar disorders. Four patients exhibited permanent neurological sequelae including cerebellar, pyramidal and extra-pyramidal signs after a long-term therapy with this association. Fever, stupor and pulmonary event were initially present. Neuropathological findings in one case only showed selective degeneration of cerebellar Purkinje cells, also noted as a characteristic feature in heat stroke and malignant hyperthermia. Lithium carbonate may be the main factor of neurotoxicity but hyperthermic states are probably involved in determinating brain damage, particularly cerebellar lesions.

Adult↗
PubMedDate not supplied

The "temporal processing deficit" hypothesis in dyslexia: new experimental evidence.

The notion that developmental dyslexia may result from a general, nonspecific, defect in perceiving rapidly changing auditory signals is a current subject of debate (so-called "temporal processing deficit" hypothesis). Thirteen phonological dyslexics (age 10-13 years) and 10 controls matched for chronological and reading age were compared on a temporal order judgment (TOJ) task using the succession of two consonants (/p/-/s/) within a cluster. In order to test the relevance of the temporal deficit hypothesis, the task also included two additional conditions where either the two stimuli were artificially slowed or the interstimulus interval was expanded. As expected, the TOJ performance was significantly poorer in dyslexics than in controls. Moreover, in the "slowed speech" condition dyslexics' performance improved to reach the normal controls' level, whereas no significant improvement occurred when increasing the interstimulus interval. Finally dyslexics' performances, especially on the slowed condition, were found correlated with several tests of phonological processing (phoneme deletion, rhyme judgment, and nonword spelling tasks). These results lend support to the general temporal deficit theory of dyslexia.

Adolescent↗
PubMedDate not supplied

Intensive training of phonological skills in progressive aphasia: a model of brain plasticity in neurodegenerative disease.

Three patients with a typical syndrome of nonfluent primary progressive aphasia (Mesulam's syndrome) were trained daily with a remediation protocol including auditory exercises specifically designed to involve several aspects of phonological processing, a domain known to be specifically affected in the condition. The speech content of the exercises was based on the temporal theory of phonological processes according to which increasing the duration of formant transition should facilitate phoneme discrimination and phoneomic awareness. Significantly improved performance on the trained tasks was demonstrated in the three patients. Improvement further generalized to other tasks such as nonword repetition and reading. We conclude that such results (1) argue for using intensive focused therapy of language impairment in neurodegenerative disorders, (2) may constitute a good model of brain plasticity in neurodegenerative disorders in general, and (3) support theories of phonological processing emphasizing temporal features of the auditory signal.

Aged↗
PubMedDate not supplied

Preparation and characterization of ofloxacin microspheres for the eradication of bone associated bacterial biofilm.

Biodegradable polymers for localized delivery of antibiotics have emerged as an important approach to treating orthopaedic infections. In chronic forms of osteomyelitis which are thought to be associated with bacterial biofilm, localized delivery of a suitable antibiotic is desirable. This paper describes the formulation and in vitro evaluation of biodegradable ofloxacin microspheres for the eradication of bone associated bacterial biofilm infections. Ofloxacin microspheres were formulated using poly(glycolic acid-co-DL-lactic acid) (PGLA) by the emulsion solvent evaporation technique. The effects of process parameters such as phase volume, poly(vinyl alcohol) (PVA) concentration, and viscosity grade of the polymer during preparation on encapsulation efficiency (EEF) and in vitro release profiles were investigated. An increase in the phase volume or volume fraction from 21 to 35% at a constant internal phase volume resulted in an increase in EEF from 34 to 74%. Increasing PVA concentration from 0.25 to 2.5% w/v at a constant phase volume or volume fraction did not have an effect on the EEF. Ofloxacin release from the microsopheres was biphasic with an initial burst release followed by a slow release phase. An optimum slowing down of release was observed when the phase volume was 29%. Above and below this phase volume, release of ofloxacin was higher. The higher the viscosity grade of the polymer used for the preparation of microspheres, the higher the PVA concentration needed to prepare microspheres with slower release. The study indicates that various rates of ofloxacin release is possible by varying formulation conditions. This should provide a means for formulating sustained release microspheres of antibiotics for the treatment of biofilm infections associated with the bone.

Anti-Infective Agents↗
PubMedDate not supplied

Pharmacokinetic and pharmacodynamic analysis of sedative and amnesic effects of lorazepam in healthy volunteers.

This study describes for the first time the pharmacokinetic and pharmacodynamic modeling of the psychomotor and amnesic effects of a single 2-mg oral dose of lorazepam in healthy volunteers. Twelve healthy volunteers were included in this randomized, double-blinded, placebo-controlled two-way crossover study. The effect of lorazepam was examined for a battery of tests that explored mood, vigilance, psychomotor performance, and memory. The pharmacokinetic and pharmacodynamic modeling of these tests was performed using the indirect response model. Vigilance and psychomotor performance were significantly impaired. Short-term memory was not affected, but a paradoxical tendency to improvement of the score was observed 0.4 hours after drug intake. Significant impairment was observed for immediate and delayed cued verbal recall, for immediate and delayed free recall, and for picture recognition as well as for visual-verbal recall, but not for cued visual-spatial recall or priming. Globally, the different effects were greatest between 0.4 to 3 hours after dosing. However, the time course profile of the recovery period suggests a possible dissociation between the kinetics of the effects of lorazepam on vigilance, psychomotor performance, and visual episodic memory, on the one hand, and on verbal episodic memory, on the other. The pharmacokinetic and pharmacodynamic model used two compartments with first-order absorption to describe the lorazepam concentrations and an indirect response model with inhibition or stimulation of Kin to describe the effects. The mean values for calculated median effective concentration (EC50) derived from the pharmacokinetic and pharmacodynamic modeling of the different tests ranged from 11.3 to 39.8 ng/mL. According to these EC50 values, lorazepam seemed to be more potent on the delayed-recall trials than on the immediate-recall trials; similar observations were made concerning the free-recall versus cued-recall trials. The previously stated results suggest that the tests performed in this study represent sensitive measurements of the effects of lorazepam on the central nervous system. Moreover, the parameter values derived from pharmacokinetic and pharmacodynamic modeling, especially, the EC50 values, may provide sensitive indices that can be used to compare the central nervous system effects of benzodiazepines.

Adolescent↗
PubMedDate not supplied

Proportional localization system for anatomical interpretation of cerebral computed tomograms.

The existence of individual variations in size and shape of the human brain constitutes a problem for the anatomical interpretation of brain reconstructed images obtained from scanning devices; it is, for example, responsible for most of the inaccuracies in reading CT scans. One way to account for these variations is to use a proportional localization system. In the 1960s a group of neurosurgeons developed such a system based on two pivotal intracerebral structures, the anterior and the posterior commissures; they published an atlas consisting of horizontal, coronal, and sagittal brain sections interpreted in the proportional system. The atlas also included standard proportional brain schemes based on anatomical and radiological studies on large numbers of individuals. In this article we report a target localization experiment that we carried out to determine if this atlas could be used as a reference for a more accurate interpretation of CT and, eventually, of positron emission tomography (PET) and nuclear magnetic resonance (NMR) scans. Ten radiopaque small targets were inserted through the skull in the cortex of three cadavers; head CT was performed, and the atlas was used for predicting the cortical location of the targets seen on the CT images: The predictions were confirmed. These results strongly support the use of the proportional atlas for the interpretation of CT as well as of PET and NMR scans.

Anatomy, Artistic↗
PubMedDate not supplied

Kufs' disease presenting as progressive dementia with late-onset generalized seizures: a clinicopathological and electrophysiological study.

A 32-year-old woman presented with increasing motor difficulties and memory disturbances. Neurological examination only showed mild cerebellar and extrapyramidal symptoms, whereas neuropsychological evaluation disclosed severe cognitive changes consistent with dementia. Her motor and mental status progressively deteriorated until death, which occurred 5 years after the first admission. One year before death, while she was almost bedridden, symptoms of myoclonic epilepsy first appeared, with frequent generalized seizures and generalized myoclonus, occurring especially upon sensory stimulation or passive joint movements. Pathological examination showed neuronal inclusions typical of Kufs' disease. This case, with primary progressive dementia and late-onset myoclonic epilepsy, differs from previously reported cases. Three special electrophysiological features were abnormal, "giant", evoked potentials; unusually marked photosensitivity; and seizure induction by any sensory stimulation.

Adult↗
PubMedDate not supplied

Startle response: epileptic or non-epileptic? The case for "flash" SMA reflex seizures.

A 19-year-old woman complained of long-standing, frequent, debilitating brusque movements triggered by unexpected stimuli. She was neurologically normal and neuroimaging was also normal. Conspicuous startle reactions were easily reproduced under EEG and video monitoring: the interictal EEG was normal, the ictal recordings doubtful; clinically, the startle reaction was asymmetric, with elevation of the left limbs. The diagnosis of hyperekplexia and startle epilepsy were discussed. We learned that she had been evaluated at age 3-4 months for spontaneous, generalised tonic-clonic seizures and "infantile spasms", in fact for early-onset startle reactions triggered by noise or contact, in association with prominent EEG changes. A full remission had been achieved under ACTH therapy, but the startle reactions had reappeared at around age six. The patient was successfully treated with carbamazepine. The history, clinical and neurophysiological data led us to discuss the diagnosis of hyperekplexia and startle epilepsy. We concluded that the patient had an unusual form of cryptogenic focal epilepsy originating from the supplementary motor area, presenting as strictly stimulus-triggered "flash" seizures.

Adult↗
PubMedDate not supplied

Seroprevalence of hepatitis C virus specific antibodies among Iraqi children with thalassaemia.

The seroprevalence of hepatitis C virus (HCV) specific antibodies and HCV genotypes distribution were studied among 559 Iraqi children with thalassaemia in receipt of repeated blood transfusions. HCV-specific antibodies were detected in 376 (67.3%) serum samples using third-generation enzyme immunoassay and confirmatory immunoblot assays. Of 78 randomly selected sera, 48 (61.5%) were HCV-RNA positive. HCV genotypes 1a, 1b, 4 and mixed 1b and 4 were demonstrated in 13 (27.1%), 11 (22.9%), 17 (35.4%) and 7 (14.6%) sera respectively. Strict measures for the controlling the spread of HCV are needed by introducing advanced techniques for blood donor screening.

Blood Donors↗
PubMedDate not supplied

[Diagnostic criteria of depressive pseudodementia].

Ten patients fulfilling the DSM III (A, B, C, D) criteria for both dementia and major depression and presenting the diagnostic dilemma of depressive pseudodementia were included in a prospective study in search of indices for the differential diagnosis of depressive pseudodementia (DPSD) and organic dementia (OD). Patients were assessed with the Hamilton Depression Rating Scale (HDRS), the Blessed Dementia Rating Scale (BDRS), the Wells's criteria, the Mini Mental State (MMS), computerized tomography (CT scan) of the brain, the dexamethasone suppression test (DST), total plasma 3-methoxy-4-hydroxyphenylglycol (MHPG) and sleep electroencephalograms (EEG). Patients suffering from DPSD were defined as showing an improvement higher than 50% in both the HDRS et BDRS scores following adequate antidepressant treatment. Wells's criteria, MMS scores, CT scan and DST do not contribute to the separation of DPSD (n = 6) and OD (n = 4). On the contrary, plasma MHPG levels higher than 35 ng/ml and EEG measures of sleep structure and REM sleep significantly differentiate the two groups.

Aged↗
PubMedDate not supplied

[Athymhormic syndrome caused by bilateral striato-capsular infarction. Moyamoya disease in adults].

A 49 year-old women with no medical history suddenly presented bilateral striato-capsular infarct causing frontal-like behavioural disturbances associating inertia with loss of drive, interest and affect, and preservation of intellectual function ("athymhormic syndrome" or "loss of psychic self-activation"). Ischaemic lesions mainly affected right globus pallidus and left lentiform nucleus with no involvement of the caput of the nuclei caudati. Such changes were close to anoxic lesions known to cause the same symptomatology. Infarction was attributed to a Moyamoya disease on angiographic data. Bilateral involvement of basal ganglia, arterial borderzones or both, may explain the frequent occurrence of neuropsychological disturbances in Moyamoya disease.

Cerebral Angiography↗
PubMedDate not supplied

[Isolated involvement of motivated behavior and basal ganglia diseases].

Focal brain lesions involving bilaterally either the globus pallidus, the corpus striatum or the deep frontal white matter, may result in a distinctive syndrome whereby patients become totally inert, with massive decrease in spontaneous behaviour, despite lack of obvious cognitive and mood disturbances. This syndrome has been variously labelled as "loss of psychic autoactivation" (Laplane et al.), "loss of action initiation and maintaining" (Ali Chérif et al.), "athymhormic syndrome" (Habib & Poncet). The most salient feature of this syndrome lies in the dissociation found between dramatic decrease in spontaneous mental (gestural, linguistic, emotional) productions, on the one hand, and almost normal productions given in response to external orders or stimulations, on the other hand. Patients are totally aware of these behavioural changes. According to their own reports, they do not suffer from these changes, they are not depressed or anxious, they do not make any plans or projects. Finally, a striking feature of their subjective experience is that they very often report an absence of spontaneous thought ("mental emptiness"). It is all though psychophysiological processes responsible for releasing and maintaining self-initiated behaviours or behaviours occurring in response to appetitive or aversive environmental stimulations, were impaired; this impairment may thus be termed a "motivational" disorder. Observations of the brain lesional substrate of this syndrome have focused on several sub-cortical neural structures, whose common feature is to be tightly connected with elements of the dopaminergic meso-limbic system, known from abundant experimental evidence to be chiefly involved in the regulation of motivated behaviour.

Basal Ganglia Diseases↗
PubMedDate not supplied

[Primary progressive aphasia (Mesulam syndrome)].

Primary progressive aphasia is defined as a gradually appeared and gradually worsening disorder of speech without any major alteration of the other cognitive functions. It is regarded by some authors as a syndrome which may be due to various degenerative diseases of the cerebral cortex (notably Alzheimer's disease, owing to its frequency), while others see in it an autonomous disease related to a neuropathological process that is distinct from the main degenerative dementias. The principal clinical particularity of primary progressive aphasia is that it spares the patient's autonomy for a long time, but ultimately turns into global dementia. Despite the diversity of aphasic aspects accompanied or not, in neuroimaging, by morphological and metabolic asymmetry to the expense of the left hemisphere, a review of the autopsy cases published shows that the vast majority corresponded to a neuropathological pattern devoid of the characteristic features of Alzheimer's disease and nearer to Pick's disease. In practice, the diagnosis of Alzheimer's disease can be excluded in all patients whose clinical presentation and cerebral neuroimaging results are compatible with primary progressive aphasia. Moreover, the fact that this new clinicoanatomical entity has been individualized constitutes a definite step towards a better comprehension of degenerative dementias.

Aged↗
PubMedDate not supplied

[Activity and motivational disorders in neurology: proposal for an evaluation scale].

Isolated disturbances of motivation and action have recently been reported following focal (anoxic, toxic or ischemic) lesions of the basal ganglia. Their postulated mechanism is thought to involve bilateral dysfunction in a cortico-subcortical loop centered on the limbic part of the striato-pallidum. Such disturbances also occur as a consequence of more diffuse brain damage, such as in vascular or degenerative dementias. Clinically, patients show dramatic decrease in spontaneous acts, whereas the same acts are correctly performed on external demand (so-called "loss of auto activation"). Moreover, they also demonstrate a special "loss of interest, affect and elan vital" which is relevant to both diagnosis and physiopathologic issues. Finally, they very often report a unique feature of decrease or absence of spontaneous thoughts, which is reversible upon external stimulation as well. In this article, the various clinical features of this syndrome are reviewed, based on the relevant literature as well as the author's personal experience. A new rating scale is proposed in order to evaluate specifically disorders of motivation and action in brain-damaged patients.

Affective Symptoms↗
PubMedDate not supplied

[Partial lipodystrophy, hypocomplementemia and glomerulonephritis].

Renal involvement is found in 20 to 50% of cases of Partial lipodystrophy (PLD). We report 8 cases of PLD of which 6 had a glomerular nephropathy and 2 had no renal disease but all had persistent hypocomplementemia and 5 had circulating nephritic factor (C3NeF). The analysis of these cases and of all the cases reported in the literature shows the specificity of the glomerular involvement. Membranoproliferative glomerulonephritis (MPGN) with dense intramembranous deposits is a constant finding in PLD with renal involvement. This variety of MPGN is well known for being associated with persistent hypocomplementemia. However, the presence of hypocomplementemia and C3NeF in patients with PLD but without nephritis raises the question of the interrelationship between alternative pathway complement activation and the development of MPGN with or without lipodystrophy. There is no valid explanation in the present state of knowledge for the association of partial lipodystrophy hypocomplementemia, and MPGN. From the answer to this problem should emerge a better understanding of the role of complement in renal disease and in particular in the unusual form of glomerular injury seen in MPGN.

Adolescent↗