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Biomedical subjects

J M Polo

Publications and source records attributed to J M Polo.

At least 19 recordsLinked to original sources
PubMed2006

Sindbis virus replicon particles encoding calreticulin linked to a tumor antigen generate long-term tumor-specific immunity.

Alphavirus vectors have emerged as a promising strategy for the development of cancer vaccines and gene therapy applications. In this study, we used the replication-defective vaccine vector SIN replicon particles from a new packaging cell line (PCL) to develop SIN replicon particles encoding calreticulin (CRT) linked to a model tumor antigen, human papillomavirus type 16 (HPV16) E7 protein. The linkage of CRT to E7 in SIN replicon particles resulted in a significant increase in E7-specific CD8(+) T-cell precursors and a strong antitumor effect against E7-expressing tumors in vaccinated mice. SINrep5-CRT/E7 replicon particles enhanced presentation of E7 through the major histocompatibility complex (MHC) class I pathway by infecting dendritic cells (DCs) directly and pulsing DCs with lysates of cells infected by SINrep5-CRT/E7 replicons. Vaccination of immunocompromised (BALB/c nu/nu) mice with SINrep5-CRT/E7 replicon particles also generated significant reduction of lung tumor nodules, suggesting that antiangiogenesis may contribute to the antitumor effect of SINrep5-CRT/E7 replicon particles. Furthermore, SINrep5-CRT/E7 replicon particles generated long-term in vivo tumor protection effects and antigen-specific memory immunities. We concluded that the CRT strategy used in the context of SIN replicon particles facilitated the generation of a highly effective vaccine for cancer prophylaxis and immunotherapy.

Analysis of Variance↗
PubMed2004

Decreased oxidative stress in prehepatic portal hypertensive rat livers following the induction of diabetes.

1. Oxidative stress (OS) is a biological entity indicated as being responsible for several pathologies, including diabetes. Diabetes can also be associated with human cirrhosis. Portal hypertension (PH), a major syndrome in cirrhosis, produces hyperdynamic splanchnic circulation and hyperaemia. The present study was designed to investigate the occurrence of OS in prehepatic PH rat livers following the induction of diabetes. 2. Five groups of rats were used: control, sham operated, chronic diabetes (induced with a single dose of streptozotocin at 60 mg/kg, i.p.), prehepatic PH and chronic diabetic plus prehepatic PH. The occurrence of OS was determined in liver homogenates by measuring hydroperoxide-initiated chemiluminescence and the activity of anti-oxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase). 3. Prehepatic PH produced a significant increase in hydroperoxide-initiated chemiluminescence in the liver compared with control and sham-operated rats, whereas the liver in chronic diabetic rats showed no difference. However, chemiluminescence values decreased almost by 50% in the chronic diabetic plus prehepatic PH group. Concomitantly, the activities of the anti-oxidant enzymes in chronic diabetes, prehepatic PH and chronic diabetic plus prehepatic PH groups were decreased (P < 0.05 vs control and sham-operated groups). 4. Livers from the chronic diabetic group did not show any evidence of the occurrence of OS, whereas the prehepatic PH group showed the occurrence of OS. The association of PH and chronic diabetes resulted in a significant decrease in the occurrence of OS, which could be explained by an anti-oxidant response to an OS.

Animals↗
PubMed2002

Friedreich ataxia with minimal GAA expansion presenting as adult-onset spastic ataxia.

Around a quarter of Friedreich ataxia (FA) patients, despite being homozygous for GAA expansion within the FRDA gene, show atypical presentations. Our aim is to describe the case of three brothers with long-term follow-up suffering from late onset FA manifested with spastic ataxia. The three patients belong to a family with occipital dysplasia (OD) and Chiari I malformation previously reported by us. We have carried out serial examinations since 1977. Electrophysiological and neuroimaging studies, and molecular genetic analyses of hereditary ataxias are available in all three patients. Onset of symptoms occurred between 25 and 35 years. The clinical picture consisted of progressive spastic gait, truncal and limb ataxia, dysarthria, nystagmus, hyperreflexia with knee and ankle clonus and extensor plantar response, and mild hypopallesthesia. Ages at present vary between 50 and 59. One patient is wheelchair-bound but the other two are able to walk with support. Leaving OD aside, skeletal anomalies are not prominent. All three patients showed cardiomyopathy. MR imaging revealed atrophy of the cerebellum and spinal cord. Motor and sensory nerve conduction velocities were normal. Central conduction time of both motor and sensory pathways was delayed or unobtainable. All three patients were homozygous for the GAA expansion, the smaller expanded allele ranging between 131 and 156 repeats. Four heterozygotic carriers were detected among non-ataxic relatives including one with OD; furthermore, an asymptomatic OD patient showed normal genotype. We conclude that adult onset spastic ataxia is a distinctive FA phenotype associated with minimal GAA expansion. This phenotype represents a new cause of selective distal degeneration of central sensory axons. The present concurrence of OD and FA reflects coincidental cosegregation of two different inherited disorders.

Adult↗
PubMed2001

Human immunodeficiency virus type 1 Gag-specific vaginal immunity and protection after local immunizations with sindbis virus-based replicon particles.

The majority of human immunodeficiency virus (HIV) infections occur through vaginal and rectal transmission. In seeking a safe, nonreplicating gene-delivery vector that can induce mucosal and systemic immune responses and protection, Sindbis virus-based replicon particles expressing HIV-1 Gag (SIN-Gag) were developed. In mice, after nasal or intramuscular immunization with SIN-Gag and vaginal challenge with vaccinia virus (VV) expressing HIV-1 Gag (VV-Gag), CD8(+) T cell-mediated responses were detected locally, in the vaginal mucosa and in the draining iliac lymph nodes (ILNs), and systemically, in the spleen. However, the mice were not protected against VV-Gag replication in the ovaries. In contrast, after vaginal or rectal immunization with SIN-Gag and vaginal challenge with VV-Gag, despite lower local CD8(+) T cell-mediated responses in the vaginal mucosa and ILNs, the mice were protected against VV-Gag replication in the ovaries. Therefore, local immunization with SIN-Gag induced both local mucosal cell-mediated responses and protection.

AIDS Vaccines↗
PubMed2001

Chromium (VI) induces oxidative stress in the mouse brain.

Potassium dichromate was given to female Swiss mice (25 mg/kg per day) orally in water for 1-3 days. Brain homogenates were prepared to evaluate the occurrence of oxidative stress in this organ through the measurement of the antioxidant defense levels. and the extent of lipid peroxidation. In addition, mitochondrial fractions were isolated from brain homogenates to determine the production of reactive oxygen species in this subcellular fraction. The administration of potassium dichromate for 3 days caused increases of 72 and 74% in superoxide dismutase and catalase activities, respectively, in the homogenates. The treatment with this metal for 3 days increased brain homogenate chemiluminescence and thiobarbituric acid-reactive substances by 34 and 29%, respectively. The brain contents of the non-enzymatic antioxidants alpha-tocopherol and sulfhydryl groups decreased by 35 and 32%, respectively. Ascorbic acid levels were not modified by the administration of potassium dichromate. Finally, there was a significant increment in the mitochondrial production of oxidants in the brain of treated mice as compared with controls. These results suggest that chromium(VI) produces an increased formation of reactive oxygen species and brain lipid peroxidation. The increase in the antioxidant enzyme activities reflects an adaptive response against oxidative stress, while the reduction in the levels of non-enzymatic antioxidants might be due to their reaction with reactive oxygen species generated during the metabolism of chromium(VI).

Administration, Oral↗
PubMed2001

Development of an MFG-based retroviral vector system for secretion of high levels of functionally active human BMP4.

We sought to develop a retroviral vector system that would produce secretion of high levels of bone morphogenetic protein (BMP)-4 by optimizing the expression construct and developing an improved retroviral vector. Replacement of the propeptide domain of BMP4 with that of BMP2 increased the secretion level of mature BMP4 protein in transduced cells. The intact BMP2 pro-peptide sequence was essential, as deletion of a small part of the propeptide sequence of BMP2 from the BMP2/4 hybrid construct diminished BMP4 expression and secretion. Addition of a hemaglutinin tag to the carboxy terminus of BMP4 abolished the bioactivity of secreted BMP4. Transduction of rat marrow stromal cells (and fibroblasts) with an MFG-based retroviral vector pseudotyped with VSV-G envelope containing this BMP2/4 hybrid expression construct led to secretion of very high levels of mature BMP4 in conditioned medium (up to 1 microg/10(6) cells/24 hours). The secreted BMP4 was biologically active, as it induced alkaline phosphatase expression in C2C12 cells. The transduced rat marrow stromal cells expressing mature BMP4 induced de novo ectopic bone formation in syngenic immune-competent rats. We have developed an MFG-based retroviral vector system that causes secretion of high levels of functionally active human BMP4 protein.

Animals↗
PubMed2000

Replicon vectors derived from Sindbis virus and Semliki forest virus that establish persistent replication in host cells.

Alphavirus replicon vectors are well suited for applications where transient, high-level expression of a heterologous gene is required. Replicon vector expression in cells leads to inhibition of host macromolecular synthesis, culminating in eventual cell death by an apoptotic mechanism. For many applications, including gene expression studies in cultured cells, a longer duration of transgene expression without resulting cytopathic effects is useful. Recently, noncytopathic Sindbis virus (SIN) variants were isolated in BHK cells, and the mutations responsible were mapped to the protease domain of nonstructural protein 2 (nsP2). We report here the isolation of additional variants of both SIN and Semliki Forest virus (SFV) replicons encoding the neomycin resistance gene that can establish persistent replication in BHK cells. The SIN and SFV variant replicons resulted from previously undescribed mutations within one of three discrete regions of the nsP2 gene. Differences among the panel of variants were observed in processing of the nonstructural polyprotein and in the ratios of subgenomic to genomic RNAs. Importantly, high-level expression of a heterologous gene was retained with most replicons. Finally, in contrast to previous studies, efficient packaging was obtained with several of the variant replicons. This work expands the utility of noncytopathic replicons and the understanding of how alphavirus replicons establish persistent replication in cultured cells.

Genetic Vectors↗
PubMed2000

Infection of human dendritic cells by a sindbis virus replicon vector is determined by a single amino acid substitution in the E2 glycoprotein.

The ability to target antigen-presenting cells with vectors encoding desired antigens holds the promise of potent prophylactic and therapeutic vaccines for infectious diseases and cancer. Toward this goal, we derived variants of the prototype alphavirus, Sindbis virus (SIN), with differential abilities to infect human dendritic cells. Cloning and sequencing of the SIN variant genomes revealed that the genetic determinant for human dendritic cell (DC) tropism mapped to a single amino acid substitution at residue 160 of the envelope glycoprotein E2. Packaging of SIN replicon vectors with the E2 glycoprotein from a DC-tropic variant conferred a similar ability to efficiently infect immature human DC, whereupon those DC were observed to undergo rapid activation and maturation. The SIN replicon particles infected skin-resident mouse DC in vivo, which subsequently migrated to the draining lymph nodes and upregulated cell surface expression of major histocompatibility complex and costimulatory molecules. Furthermore, SIN replicon particles encoding human immunodeficiency virus type 1 p55(Gag) elicited robust Gag-specific T-cell responses in vitro and in vivo, demonstrating that infected DC maintained their ability to process and present replicon-encoded antigen. Interestingly, human and mouse DC were differentially infected by selected SIN variants, suggesting differences in receptor expression between human and murine DC. Taken together, these data illustrate the tremendous potential of using a directed approach in generating alphavirus vaccine vectors that target and activate antigen-presenting cells, resulting in robust antigen-specific immune responses.

Adenovirus E2 Proteins↗
PubMed2000

Fatal familial insomnia: clinical, neuropathological, and genetic description of a Spanish family.

The clinical presentation and evolution, neuropathological findings, and genotyping of three members of a Spanish family affected with fatal familial insomnia are reported. The mother and two of her offspring developed a rapidly evolving disease with insomnia and behavioural disorders as the initial symptoms and died between 5 and 10 months after the onset of the illness. Frontal brain biopsy in the mother disclosed only non-significant spongiosis, and full neuropathological examination of her offspring showed thalamic and olivary degeneration with isolated focal cortical spongiosis. Genetic examination could only be performed in the contemporary patients and both harboured the prion protein (PrP) 178Asn mutation and homozygous 129 Met/Met genotype.

Biopsy↗
PubMed2000

Continuous facial myokymia in multiple sclerosis: treatment with botulinum toxin.

Continuous facial myokymia (CFM) is an involuntary undulating, vermicular movement that spreads across facial muscles and is associated with a characteristic electromyographic pattern. It is an infrequent clinical sign that almost always occurs in intrinsic brainstem lesions, particularly in multiple sclerosis (MS). It is usually present for only a few weeks, but it may persist for long periods of time being very troublesome for patients. We report 2 cases with MS and continuous hemifacial myokymia persisting for up to 1 month which disappeared after injection of botulinum toxin. Botulinum toxin A (BTX-A) has been used successfully to treat a variety of focal dystonias and occasionally in orbicularis myokymia, but its use has not been reported in continuous hemifacial myokymia. BTX-A appears to be effective and safe for treating persistent facial myokymia in MS patients.

Adult↗
PubMed2000

[Progressive anarthria: one case without lingual apraxia].

Progressive anarthria is a focal cortical degenerative disorder characterized by a profound, progressive alteration in speech without impairment in other cognitive domains. The first symptoms consist of an alteration in the articulation of speech producing telegraphic speech. The disorder invariably progress towards anarthria by deprogramming of the phonation and orolingual movements (bucophonetic apraxia). This type of apraxia is usually associated with orolinguofacial apraxia and it has been anatomofunctionally correlated with frontal opercular involvement of left predominance. The patient presented as progressive anarthria in the absence of manifest orolingual apraxia associated with a predominance of cortical atrophy in the right frontal operculum. This semiological dissociation emphasizes the importance of bucophonatory apraxia in the pathophysiology of progressive anarthria.

Apraxias↗
PubMed2000

Alphavirus DNA and particle replicons for vaccines and gene therapy.

Alphaviruses have several features that make them attractive as gene delivery platforms, and vectors derived principally from Sindbis virus (SIN), Semliki Forest virus (SFV), and Venezuelan equine encephalitis virus (VEE), are currently being developed as prophylactic and therapeutic vaccines for infectious diseases and cancer. Alphavirus vectors, termed "replicons", retain the nonstructural protein genes encoding the viral replicase, that in turn programme high level cytoplasmic amplification of the vector RNA. We have developed plasmid DNA and recombinant vector particle delivery systems derived from the prototype alphavirus, SIN. Each system uses RNA polymerase II-based expression of alphavirus genome components and both vector formats are highly efficacious towards inducing robust antigen-specific immune responses in vaccinated animals. To increase the potency of SIN vector particles, which are not known to be lymphotropic, the tropism was re-directed for efficient infection of dendritic cells, both in vitro and in vivo.

Alphavirus↗
PubMed1999

Stable alphavirus packaging cell lines for Sindbis virus and Semliki Forest virus-derived vectors.

Alphavirus vectors are being developed for possible human vaccine and gene therapy applications. We have sought to advance this field by devising DNA-based vectors and approaches for the production of recombinant vector particles. In this work, we generated a panel of alphavirus vector packaging cell lines (PCLs). These cell lines were stably transformed with expression cassettes that constitutively produced RNA transcripts encoding the Sindbis virus structural proteins under the regulation of their native subgenomic RNA promoter. As such, translation of the structural proteins was highly inducible and was detected only after synthesis of an authentic subgenomic mRNA by the vector-encoded replicase proteins. Efficient production of biologically active vector particles occurred after introduction of Sindbis virus vectors into the PCLs. In one configuration, the capsid and envelope glycoproteins were separated into distinct cassettes, resulting in vector packaging levels of 10(7) infectious units/ml, but reducing the generation of contaminating replication-competent virus below the limit of detection. Vector particle seed stocks could be amplified after low multiplicity of infection of PCLs, again without generating replication-competent virus, suggesting utility for production of large-scale vector preparations. Furthermore, both Sindbis virus-based and Semliki Forest virus-based vectors could be packaged with similar efficiency, indicating the possibility of developing a single PCL for use with multiple alphavirus-derived vectors.

Alphavirus↗
PubMed1999

An early description of striatonigral degeneration.

Our aim was to revisit the papers published by Scherer 1933 describing four cases of sporadic olivopontocerebellar atrophy (OPCA) thought to represent the earliest description of striatonigral degeneration. One should note that extrapyramidal rigidity associated with OPCA was then considered a type of cerebellar parkinsonism. Two of Scherer's four patients had severe parkinsonism masking cerebellar signs. Pathologically both cases displayed marked degeneration of the striatum and nigra and partially developed pontocerebellar atrophy. Cerebellar ataxia was the outstanding feature in the other two, their pathological study showing severe pontocerebellar lesions and incipient striatonigral atrophy. Scherer stated that the severity of parkinsonism in OPCA is not correlated with the degree of cerebellar degeneration but with that of striatum and nigra. We conclude that Scherer gave the first accurate description of striatonigral degeneration. Moreover, his contribution was essential in ruling out the prevalent notion of cerebellar parkinsonism in OPCA.

Diagnosis, Differential↗
PubMed1999

Castleman's disease associated with chronic inflammatory demyelinating polyradiculoneuropathy: a clinical and electrophysiological follow-up study.

Castleman's disease (CD), or angiofollicular lymph node hyperplasia, is a rare lymphoproliferative disorder that can be associated with peripheral neuropathy. We report the long-term follow-up of a patient with a chronic inflammatory demyelinating polyradiculoneuropathy complicating the mediastinal form of classic CD who improved notably with immunosuppressive therapy. Our findings suggest that serial electrophysiological studies may be useful for monitoring treatment efficacy.

Aged↗
PubMed1999

Neuroimaging diagnosis of Tolosa-Hunt syndrome: MRI contribution.

OBJECTIVE: To present our experience in the neuroradiological diagnosis of six patients with Tolosa-Hunt syndrome. METHODS: Computerized tomograms and MRI, with and without contrast enhancement, of the cranium and orbits of patients fulfilling IHS criteria for the diagnosis of Tolosa-Hunt syndrome were analyzed. RESULTS: Standard CT scan, with and without contrast enhancement, disclosed an enlarged cavernous sinus in one patient and was normal in the remaining five. In comparison, MRI was clearly abnormal in the four patients on whom it was performed, showing a convex enlargement of the symptomatic cavernous sinus by an abnormal tissue isointense with gray matter on short TR/TE images and iso-hypointense on long TR/TE scans. This abnormal tissue markedly increased in signal intensity after contrast injection and, in two patients, extended into contiguous regions, mainly the orbital apex and subtemporal fossa ipsilaterally. One patient had follow-up studies after successful treatment with corticosteroids. Although diminished in size, the abnormal tissue was still visible on MRI after 3 months of treatment and only disappeared after 6 months of treatment. CONCLUSIONS: These MRI findings help in the differential diagnosis of the Tolosa-Hunt syndrome from conditions such as meningioma, lymphoma, and sarcoidosis, as well as confirming the similarities of the Tolosa-Hunt syndrome and orbital pseudotumor. In the presence of painful ophthalmoplegia, the finding by MRI of cavernous sinus enlargement, with the herein described signal and extension characteristics and slow resolution with corticosteroid treatment, is highly suggestive of the Tolosa-Hunt syndrome.

Acoustic Stimulation↗
PubMed1999

Tolosa-Hunt syndrome: focus on MRI diagnosis.

Experience with modern neuroimaging techniques, computed tomography (CT) and magnetic resonance imaging (MRI) scans, in the diagnosis of Tolosa-Hunt syndrome (THS) is reviewed. Conventional CT scan remains normal in about two-thirds of these patients. In the reported 22 patients meeting the IHS criteria for a THS diagnosis on whom an MRI study was performed, MRI revealed a convex enlargement of the symptomatic cavernous sinus by an abnormal tissue isointense with gray matter on short TR/TE images and isohypointense on long TR/TE images. This abnormal tissue markedly increases in signal intensity after contrast injection. MRI seems also to be the ideal technique to follow progressive resolution of the abnormal tissue after steroids. Therefore, normal MRI would probably exclude THS, whereas in the appropriate clinical setting of steroid-responsive painful ophthalmoplegia, MRI showing the cavernous sinus abnormality described here suggests a diagnosis of THS. From these data, we propose that the fourth IHS criterion for THS diagnosis, "Exclusion of other causative lesions by neuroimaging and (not compulsory) carotid angiogram" should be changed to "Finding by MRI of specific cavernous sinus abnormalities (with the characteristics described herein) which slowly resolve with steroid treatment".

Humans↗