RESUMEN
OBJECTIVE: Recent findings support greater efficacy of early vs. delayed interferon beta (IFNbeta) treatment in patients with a first clinical event suggestive of multiple sclerosis (MS). We aimed to evaluate the effectiveness of early IFNbeta treatment in definite relapsing-remitting MS (RRMS) and to assess the optimal time to initiate IFNbeta treatment with regard to the greatest benefits on disability progression. METHODS: A cohort of 2,570 IFNbeta-treated RRMS patients was prospectively followed for up to 7 years in 15 Italian MS Centers. A Cox proportional hazards regression model adjusted for propensity score (PS) quintiles was used to assess differences between groups of patients with early vs. delayed IFNbeta treatment on risk of reaching a 1-point progression in the Expanded Disability Status Scale (EDSS) score, and the EDSS 4.0 and 6.0 milestones. A set of PS-adjusted Cox hazards regression models were calculated according to different times of treatment initiation (within 1 year up to within 5 years from disease onset). A sensitivity analysis was performed to assess the robustness of findings. RESULTS: The lowest hazard ratios (HRs) for the three PS quintiles-adjusted models were obtained by a cutoff of treatment initiation within 1 year from disease onset. Early treatment significantly reduced the risk of reaching a 1-point progression in EDSS score (HR = 0.63; 95% CI = 0.48-0.85; p < 0.002), and the EDSS 4.0 milestone (HR = 0.56; 95% CI = 0.36-0.90; p = 0.015). Sensitivity analysis showed the bound of significance for unmeasured confounders. INTERPRETATION: Greater benefits on disability progression may be obtained by an early IFNbeta treatment in RRMS.
Asunto(s)
Interferón beta/uso terapéutico , Esclerosis Múltiple Recurrente-Remitente/tratamiento farmacológico , Esclerosis Múltiple Recurrente-Remitente/psicología , Calidad de Vida/psicología , Adulto , Estudios de Cohortes , Femenino , Estudios de Seguimiento , Humanos , Masculino , Esclerosis Múltiple Recurrente-Remitente/epidemiología , Estudios Prospectivos , Perfil de Impacto de Enfermedad , Factores de Tiempo , Resultado del Tratamiento , Adulto JovenRESUMEN
Apoptotic deletion of autoreactive T-cells is defective in patients with multiple sclerosis (MS). Glatiramer acetate (GA) treatment seems to restore apoptosis of detrimental T-cells. We analyzed the mitochondria membrane pro- (Bax) and anti-apoptotic (Bcl- 2) and cytosolic pro-apoptotic (Cyt-c, APAF-1) proteins expression in peripheral lymphocytes from relapsing-remitting (RR) MS patients during GA treatment. Blood samples were collected from 8 healthy controls (HCs) and from 8 RR MS patients prior to and every three months during the 9 months of GA treatment. Peripheral blood mononuclear cells (PBMNCs) Bcl-2, Bax, Cyt-c and APAF-1 were quantified by western blot followed by densitometric scanning and Bax/Bcl-2, cytosolic Cyt-c/Bcl-2 and APAF-1/Bcl-2 ratios were calculated. T-cells were in vitro tested for oxygen consumption by a respirometric analysis. Bax/Bcl-2, cytosolic Cyt-c/Bcl-2 and APAF-1/Bcl-2 ratios in untreated MS patients were significantly (p < 0.05) lower than in HCs. Bax/Bcl-2 ratio increased (p = 0.03) and Cyt-c/Bcl-2 ratio showed a trend to increase during the 9 months of GA treatment in MS patients. A reduction of 58% and 59% in oxygen consumption by PBMNCs was evident after GA treatment in vitro or when GA treated patients' cells were compared with those from HCs, respectively. Our findings suggest that GA exerts a regulatory effect on peripheral T lymphocytes through pro-apoptosis mechanisms involving mitochondria and cytosolic proteins.
Asunto(s)
Proteínas Reguladoras de la Apoptosis/metabolismo , Apoptosis/efectos de los fármacos , Inmunosupresores/administración & dosificación , Linfocitos/efectos de los fármacos , Esclerosis Múltiple/patología , Péptidos/administración & dosificación , Adulto , Factor Apoptótico 1 Activador de Proteasas , Western Blotting/métodos , Carbonil Cianuro m-Clorofenil Hidrazona/farmacología , Estudios de Casos y Controles , Citocromos c/metabolismo , Femenino , Acetato de Glatiramer , Humanos , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Linfocitos/patología , Masculino , Persona de Mediana Edad , Esclerosis Múltiple/tratamiento farmacológico , Consumo de Oxígeno/efectos de los fármacos , Proteínas/metabolismo , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Rotenona/farmacología , Estadísticas no Paramétricas , Factores de Tiempo , Desacopladores/farmacología , Proteína X Asociada a bcl-2/metabolismoRESUMEN
OBJECTIVES: To optimize the use of polymerase chain reaction (PCR) on cerebrospinal fluid (CSF) for the evaluation of central nervous system (CNS) white-matter lesions that along with clinical findings and magnetic resonance imaging (MRI) can allow a definite diagnosis to be made; also to evaluate treatment with zidovudine plus foscarnet. DESIGN AND METHODS: Fifteen AIDS patients with uncertain CNS white-matter lesions were identified. HIV-1 RNA, cytomegalovirus (CMV) and JC virus (JCV) DNA were measured in a total of 29 CSF samples. The results were correlated with clinical and MRI findings and treatment with zidovudine plus foscarnet was evaluated. RESULTS: Four and five out of 15 patients with CMV DNA > or = 1 : 625 and JCV DNA > or = 10(3) copies/microl detected in the CSF were diagnosed with CMV and progressive multifocal leukoencephalopathy (PML), respectively. Six patients who were CMV/JCV-negative with the highest levels of HIV RNA (median, 6.87 log10 copies/ml) in CSF were considered as having HIV-1 encephalitis. Neurological symptoms were non-supportive for diagnosis as was MRI in 11 out of 15 patients. Nine patients completed a 21-day course of zidovudine plus foscarnet. HIV RNA decreased irrespective of neurological diagnosis. All three HIV-1 encephalitis patients and two out of three patients with CMV leukoencephalopathy improved. In these two latter patients, relief of clinical symptoms coincided with decreased CMV DNA. JCV DNA remained unchanged and all three PML patients deteriorated. CONCLUSIONS: Measurement of CSF viral sequences supports the diagnosis of CNS white-matter lesions in AIDS patients. While effective therapy for PML remains elusive, treatment including zidovudine plus foscarnet may be a promising option for HIV-1 and CMV-related manifestations.
Asunto(s)
Complejo SIDA Demencia/virología , Citomegalovirus/aislamiento & purificación , ADN Viral/líquido cefalorraquídeo , Virus JC/aislamiento & purificación , Reacción en Cadena de la Polimerasa/métodos , Complejo SIDA Demencia/diagnóstico , Complejo SIDA Demencia/tratamiento farmacológico , Complejo SIDA Demencia/patología , Infecciones Oportunistas Relacionadas con el SIDA/tratamiento farmacológico , Infecciones Oportunistas Relacionadas con el SIDA/virología , Adolescente , Adulto , Fármacos Anti-VIH/uso terapéutico , Encéfalo/patología , Infecciones por Citomegalovirus/diagnóstico , Infecciones por Citomegalovirus/tratamiento farmacológico , Infecciones por Citomegalovirus/virología , Quimioterapia Combinada , Femenino , Foscarnet/uso terapéutico , VIH-1/aislamiento & purificación , Humanos , Leucoencefalopatía Multifocal Progresiva/diagnóstico , Leucoencefalopatía Multifocal Progresiva/tratamiento farmacológico , Leucoencefalopatía Multifocal Progresiva/virología , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Infecciones por Papillomavirus/diagnóstico , Infecciones por Papillomavirus/tratamiento farmacológico , Infecciones por Papillomavirus/virología , ARN Viral/líquido cefalorraquídeo , Zidovudina/uso terapéuticoRESUMEN
Isoelectric focusing of CSF and serum IgG followed by crossed immuno isoelectric focusing and direct immunofixation as well as quantitative assay of IgG and albumin were performed in 64 clinically definite multiple sclerosis patients. Intrathecal IgG synthesis was calculated according to the CSF IgG index and de novo CNS IgGsyn. Isoelectric focusing showed abnormal IgG fractions i CSF indicating increased intrathecal synthesis of oligoclonal IgG in 99% of patients. Only 62% and 70% of multiple sclerosis patients showed values of CSF IgG indices and de novo CNS IgGsyn higher than in controls. Increased intrathecal IgG synthesis was indicated more frequently by de novo CNS IgGsyn in patients with a normal CSF IgG index than by the CSF IgG index in patients with normal de novo CNS IgGsyn. All patients with blood CSF barrier damage had increased de novo CNS IgGsyn, but only 40% had an increased CSF IgG index. Isoelectric focusing seemed to be a more sensitive method to detect an increased intrathecal oligoclonal IgG synthesis than quantitative methods. Identification of abnormal IgG fractions can be performed easily and with more reproducible results by direct immunofixation than by crossed immuno isoelectric focusing. The formula for de novo CNS IgGsyn seemed more sensitive and less influenced by blood-CSF barrier damage than the CSF IgG index to detect increased intrathecal IgG synthesis in multiple sclerosis patients. No correlation was found between the CSF IgG pattern or amounts and age, duration, clinical course or therapy of the disease.
Asunto(s)
Inmunoglobulina G/biosíntesis , Esclerosis Múltiple/inmunología , Médula Espinal/inmunología , Reacciones Cruzadas , Humanos , Inmunoglobulina G/líquido cefalorraquídeo , Focalización Isoeléctrica/métodosRESUMEN
Isoelectric focusing and quantitative estimation of serum and CSF IgG were performed in 85 patients with idiopathic polyneuropathy (IP), subdivided according to the clinical course (acute, subacute, recurrent, chronic). Acute IP very frequently had an increase of oligoclonal and/or polyclonal serum IgG during the progressive phase and blood-CSF barrier damage accompanied by polyclonal IgG intrathecal synthesis during the stationary phase. Polyclonal IgG intrathecal synthesis was also present in several not acute IP and seemed to forecast unfavorable course. Oligoclonal IgG synthesis occurs very rarely within CSF but is a frequent finding in serum of patients with IP. Abnormalities of the IgG serum pattern are neither specific for any clinical course of IP nor of prognostic value. The possible significance of such findings is discussed.
Asunto(s)
Inmunoglobulina G/metabolismo , Polineuropatías/inmunología , Adolescente , Adulto , Anciano , Niño , Preescolar , Femenino , Humanos , Focalización Isoeléctrica , Masculino , Persona de Mediana Edad , Polirradiculoneuropatía/inmunología , Prednisolona/uso terapéuticoRESUMEN
Ten children affected by acute lymphoblastic leukaemia without CNS involvement were treated with a CNS prophylaxis protocol. Intrathecal methotrexate and CNS irradiation (60Co) administered at different times both induced an increase in blood-CSF barrier permeability to serum proteins (albumin, IgG, alpha 2 macroglobulin). The relationship between permeability coefficients of proteins was analysed by theoretical porous or vesicular blood-CSF barrier models. The analysis indicated that both therapeutic procedures affect endothelial pinocytosis. An increase in radius of pinocytotic vesicles from 400 to 1500 A seemed the most relevant change. The damage of endothelial barrier permselectivity could be involved in acute and late delayed toxic effects of intrathecal methotrexate and of CNS irradiation.
Asunto(s)
Proteínas Sanguíneas/metabolismo , Barrera Hematoencefálica/efectos de los fármacos , Sistema Nervioso Central/efectos de la radiación , Metotrexato/uso terapéutico , Enfermedad Aguda , Barrera Hematoencefálica/efectos de la radiación , Niño , Preescolar , Terapia Combinada , Humanos , Inyecciones Espinales , Leucemia Linfoide/tratamiento farmacológico , Leucemia Linfoide/radioterapia , Modelos BiológicosRESUMEN
Cerebrospinal fluid (CSF)/serum concentration gradients (Q) of individual proteins (albumin, IgG, alpha 2-macroglobulin) have been studied in controls and in patients in whom the lumbar CSF flow is altered (medullary compression) or the blood-CSF barrier (BCB) function impaired (acute idiopathic polyneuropathy and acute meningoencephalitis). The analysis of relationships among protein Q has been performed by total and multiple regressions and the actual BCB permeability to individual proteins has been interpreted according to the accepted theoretical porous or vesicular BCB models. The exponential Q-IgG vs. Q-albumin total regression, and the poor Q-alpha 2-macroglobulin vs. Q-albumin regression found in controls, together with the different multiple regressions among proteins and the high Q-IgG vs. Q-albumin partial regression coefficients found in medullary compression, acute idiopathic polyneuropathy and acute meningoencephalitis, indicated that different permeability mechanisms can be postulated. Heterogeneous, fairly independent permeability BCB mechanisms maintain the normal CSF/serum protein concentration gradient. Pinocytotic vesicles or pores of radius exceeding 1000-1500 A, probably located at the capillary endothelium, account for the main serum-derived CSF protein fraction(s) with large hydrodynamic radius (R). A more selective endothelial vesicular transport with a radius of 250 A transfers a negligible amount of protein from serum into CSF. Proteins with small R also enter the CSF through a set of selective pores of radius 120 A, probably at the level of the choroidal epithelium. Pinocytotic vesicles with a radius of 250 A and increased rate of formation induce the accumulation of proteins below an obstruction of lumbar CSF flow. An increased formation rate of vesicles with a radius of 450 A can explain the increased capillary permeability in nerve roots in acute idiopathic polyneuropathy. Loss of selectivity was the main feature of BCB in acute meningoencephalitis, and it seemed to be due to pores or vesicles with a radius larger than 1000-1500 A. The heterogeneity of BCB mechanisms must be taken into account when the intrathecal synthesis of a protein, also derived from serum (for example IgG), has to be measured.
Asunto(s)
Proteínas Sanguíneas/metabolismo , Barrera Hematoencefálica , Encefalopatías/líquido cefalorraquídeo , Permeabilidad Capilar , Humanos , Inmunoglobulina G/líquido cefalorraquídeo , Meningoencefalitis/líquido cefalorraquídeo , Pinocitosis , Polineuropatías/líquido cefalorraquídeo , Albúmina Sérica/líquido cefalorraquídeo , Compresión de la Médula Espinal/líquido cefalorraquídeo , alfa-Macroglobulinas/líquido cefalorraquídeoRESUMEN
BACKGROUND: There are a few and conflicting results from randomised controlled trials (RCTs) pertaining to the influence of gender in response to currently used disease modifying drugs in Multiple Sclerosis (MS). Observational studies may be especially valuable for answering effectiveness questions in subgroups not studied in RCTs. OBJECTIVE: To conduct a post-marketing analysis aimed to evaluate the gender effect on Interferon beta (IFNbeta) treatment response in a cohort of relapsing (RR) MS patients. METHODS: A cohort of 2570 IFNbeta-treated RRMS was prospectively followed for up to 7 years in 15 Italian MS Centers. Cox proportional hazards regression models were used to assess gender differences for risk of reaching 1st relapse and risk of progression by 1 point on Expanded Disability Status Scale (EDSS) score. Gender effects were also explored by a propensity score (PS) matching algorithm, and a tree-growing technique. RESULTS: The multivariate Cox Regression analyses showed that male patients had a significant (p=0.0097) lower risk for 1st relapse and a trend (p=0.0897) for a higher risk to reach 1 point EDSS progression than females. The PS matched multivariate Cox Regression confirmed these results. The RECPAM analysis showed that male sex conferred a significant reduction in the risk for 1st relapse (HR=0.86; 95% CI=0.76-0.98; p=0.0226) in the subgroup with a low pre-treatment number of bouts, and a significant increase in the risk for 1 point EDSS progression (HR=1.33; 95% CI: 1.00-1.76; p<0.05) in the subgroup with a delayed treatment, but a still young age at the start of treatment. CONCLUSION: The results of this exploratory analysis seem to suggest that male patients do not respond to IFNbeta treatment in the same way of females.
Asunto(s)
Factores Inmunológicos/uso terapéutico , Interferón beta/uso terapéutico , Esclerosis Múltiple/tratamiento farmacológico , Vigilancia de Productos Comercializados , Adulto , Estudios de Cohortes , Intervalos de Confianza , Evaluación de la Discapacidad , Método Doble Ciego , Vías de Administración de Medicamentos , Femenino , Humanos , Italia , Masculino , Oportunidad Relativa , Modelos de Riesgos Proporcionales , Análisis de Regresión , Índice de Severidad de la Enfermedad , Factores Sexuales , Adulto JovenRESUMEN
This independent, population-based surveillance study monitored, in clinical practice, the efficacy of interferon beta (IFNbeta) products in 1173 patients with multiple sclerosis (MS) from the Department of Neurological and Psychiatric Sciences, University of Bari, Italy. Relapses and Expanded Disability Status Scale (EDSS) scores were evaluated for up to 6 years for Avonex, Betaferon and Rebif 22 groups, and for up to 3 years for the Rebif 44 group. IFNbeta products produced significant reductions from baseline in relapse rates at 2, 4 and >4 years (p<0.0001), with no differences among treatments (p=0.2). A modest significant (p<0.05) increase of EDSS was observed in all treatment groups from baseline to 48 months, followed thereafter by a plateau. The IFNbeta-1b group showed more withdrawals (19%) compared with Avonex (6%) and Rebif (7%) at 6 years.
Asunto(s)
Adyuvantes Inmunológicos/uso terapéutico , Interferón beta/uso terapéutico , Esclerosis Múltiple Crónica Progresiva/tratamiento farmacológico , Esclerosis Múltiple Recurrente-Remitente/prevención & control , Adulto , Estudios de Cohortes , Evaluación de la Discapacidad , Supervivencia sin Enfermedad , Femenino , Estudios de Seguimiento , Humanos , Interferón beta-1a , Interferon beta-1b , Italia , Masculino , Persona de Mediana Edad , Esclerosis Múltiple Crónica Progresiva/inmunología , Esclerosis Múltiple Recurrente-Remitente/tratamiento farmacológico , Esclerosis Múltiple Recurrente-Remitente/inmunología , Vigilancia de la Población , Vigilancia de Productos Comercializados , Estudios Prospectivos , Prevención Secundaria , Resultado del TratamientoRESUMEN
OBJECTIVES: To confirm reduced human immunodeficiency virus type-1 (HIV-1) burden in the CSF of patients with progressive multifocal leukoencephalopathy (PML) and to verify whether this viral load coincides with the absence of inflammatory changes in the CSF. METHODS: Paired CSF and plasma samples from 17 patients with PML, 26 with non-PML cerebral opportunistic infections, nine with HIV-1 leukoencephalopathy (HIVE), and 12 neurologically asymptomatic AIDS patients were subjected to HIV-RNA titration. Tumour necrosis factor (TNF)-alpha was also measured and the CSF albumin: serum albumin ratio (Q(Alb)) was calculated. RESULTS: The CSF HIV-1 burden of patients with PML did not differ from that of neurologically asymptomatic patients (p=0.21), but was significantly lower than CSF burden of the remaining patients (non-PML opportunistic infections, p<0.001; HIVE, p<0.001). Q(Alb) was normal for all neurologically asymptomatic patients, for 86.6% patients with PML, and 62.5% patients with HIVE (p=0.09). Q(Alb) was altered in 91.6% patients with non-PML opportunistic infections. TNF-alpha in CSF was higher in patients with non-PML opportunistic infections (p<0.001) and those with HIVE (p<0.001) than in patients with PML who consistently had TNF-alpha concentrations<10 pg/ml. CONCLUSIONS: These results, while indicating a reduced HIV replication in CSF of patients with PML which might serve as a disease marker, emphasise the increased CSF HIV-RNA concentration in patients with HIVE and patients with non-PML opportunistic infections. Low concentrations of HIV-RNA in CSF coincide with reduced TNF-alpha concentrations, possibly due to particular features of PML compared with other opportunistic infections as it develops without detectable inflammatory changes in the CSF.
Asunto(s)
Síndrome de Inmunodeficiencia Adquirida/líquido cefalorraquídeo , VIH-1 , Leucoencefalopatía Multifocal Progresiva/líquido cefalorraquídeo , Leucoencefalopatía Multifocal Progresiva/virología , ARN Viral/líquido cefalorraquídeo , Factor de Necrosis Tumoral alfa/líquido cefalorraquídeo , Síndrome de Inmunodeficiencia Adquirida/complicaciones , Adulto , Femenino , Humanos , MasculinoRESUMEN
CSF and serum of 80 HIV-seropositive patients in various stages of the disease were examined. Total as well as intrathecal IgG synthesis appeared to be frequently elevated in each diagnostic group. Abnormal CSF oligoclonal IgG fractions were significantly more frequent in asymptomatic patients. CSF pleocytosis was found with a lower percentage in neurological AIDS patients. In patients subdivided according to blood T helper cell count, the distribution of the abnormal CSF parameters confirms that the immunological response in the CNS is mediated by interaction with systemic immunity.
Asunto(s)
Enfermedades del Sistema Nervioso Central/etiología , Seropositividad para VIH/metabolismo , Inmunoglobulina G/biosíntesis , Adulto , Enfermedades del Sistema Nervioso Central/sangre , Enfermedades del Sistema Nervioso Central/líquido cefalorraquídeo , Enfermedades del Sistema Nervioso Central/inmunología , Enfermedades del Sistema Nervioso Central/metabolismo , Femenino , Seropositividad para VIH/sangre , Seropositividad para VIH/líquido cefalorraquídeo , Seropositividad para VIH/inmunología , Humanos , Inmunoglobulina G/líquido cefalorraquídeo , Recuento de Leucocitos , Masculino , Persona de Mediana Edad , Linfocitos T Colaboradores-InductoresRESUMEN
Age at onset of multiple sclerosis (MS) can vary from childhood to adult life. Many reports have been carried out over the years concerning the role of age at onset in determining the disease outcome. In a sporadic MS population of 1463 patients with homogeneous clinical and demographic features, derived from three Italian neurological centres (Bari, Cagliari and Sassari), we analysed the relative weights of current age and age at onset on disease severity according to the expanded disability status scale (EDSS) score, by fixing the disease duration. The results of present study demonstrate that clinical disability in MS is influenced by the patient's age (p < 0.01) and not by the age at onset. Therefore, these data do not confirm the hypothesis that an early age at onset should be considered a favourable prognostic factor of the disease outcome.
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Esclerosis Múltiple/epidemiología , Adolescente , Adulto , Distribución por Edad , Edad de Inicio , Anciano , Análisis de Varianza , Niño , Estudios de Cohortes , Progresión de la Enfermedad , Femenino , Humanos , Italia/epidemiología , Masculino , Persona de Mediana Edad , Esclerosis Múltiple/fisiopatología , Pronóstico , Factores SexualesRESUMEN
Seven paired HIV-1 isolates from peripheral blood mononuclear cells (PMCs) and cerebrospinal fluid (CSF) of infected subjects at various stages of the disease were studied for their capacity to replicate in continuous cell lines (Molt-3 and U-937 cells) and to induce cytopathic effects "in vitro". Obtained results indicate that paired HIV-1 isolates from PMCs and CSF of the same patient can differ in their replicative activity "in vitro", suggesting that, at least in some cases, CSF isolates may represent a distinct subtype of HIV-1.
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Síndrome de Inmunodeficiencia Adquirida/microbiología , VIH-1/patogenicidad , Complejo Relacionado con el SIDA/microbiología , Síndrome de Inmunodeficiencia Adquirida/sangre , Síndrome de Inmunodeficiencia Adquirida/líquido cefalorraquídeo , Línea Celular , Células Cultivadas , Efecto Citopatogénico Viral , VIH-1/aislamiento & purificación , Humanos , Técnicas In Vitro , Monocitos/microbiología , Linfocitos T/microbiologíaRESUMEN
OBJECTIVES: To evaluate the role of proton MR spectroscopy (1H-MRS) in detecting metabolic changes in diffuse or focal lesions in the brain of patients infected with HIV. METHODS: Sixty HIV seropositive patients (25 with HIV related encephalopathies, 20 with toxoplasmosis, eight with progressive multifocal leukoencephalopathies (PMLs), and seven with lymphomas) and 22 HIV seronegative neurological controls were examined with a combined MRI and 1H-MRS technique using a Siemens 1.5 Tesla Magnetom. Spectra (Spin Echo sequence, TE 135 ms) were acquired by single voxel, localised on focal lesions in toxoplasmosis, PML, lymphomas, and HIV encephalopathies and on the centrum semiovale of neurological controls. Choline (Cho), creatine (Cr), N-acetyl aspartate (NAA), lactate, and lipids were evaluated in each spectrum and NAA/Cr, NAA/Cho, and Cho/Cr ratios were calculated. RESULTS: A significant decrease in NAA/Cr and NAA/Cho ratios were found in all HIV diagnostic groups in comparison with neurological controls (p<0.003), suggesting neuronal or axonal damage independent of brain lesion aetiology. However, the NAA/Cr ratio was significantly lower in PML and lymphomas than in HIV encephalopathies (p<0.02) and toxoplasmosis (p<0.05). HIV encephalopathies, lymphomas, and toxoplasmosis showed a significant increase in the Cho/Cr ratio in comparison with neurological controls (p<0.03) without between group differences. The presence of a lipid signal was more frequent in lymphomas (71%) than in other HIV groups (Fisher's test, p=0.00003). The presence of mobile lipid resonance together with a high Cho/Cr ratio in lymphomas may be related to an increased membrane synthesis and turnover in tumour cells. A lactate signal (marker of inflammatory reaction), was found in all but one patient with PML lesions (75%), but had a lower incidence in the other HIV diagnostic groups (Fisher's test, p=0.00024). CONCLUSION: 1H-MRS shows a high sensitivity in detecting brain involvement in HIV related diseases, but a poor specificity in differential diagnosis of HIV brain lesions. Nevertheless, the homogeneous metabolic pattern that characterises PML suggests the usefulness of 1H-MRS as an adjunct to MRI in differentiating CNS white matter lesions, such as HIV encephalopathies, from PML.