Large-scale feasibility of gene transduction into human CD34+ cell-derived dendritic cells by adenoviral/polycation complex

With a view to using multiple injections of anti-cancer dendritic cell (DC)-based vaccines, we evaluated the feasibility of the adenoviral transduction of large amounts of human CD34+ cell-derived DCs, and analysed the persistence of the transgene expression and the integrity of DC functional activity after the transduction/cryopreservation procedures. Mature DCs generated from highly enriched human CD34+ cells were transduced by a recombinant adenovirus (rAd-MFG) that carried a modified, membrane-exposed, alkaline phosphatase (AP) sequence as the reporter gene. Cationic lipids such as LipofectAmine or poly-L-lysine were mixed with the viral particles before the transduction of the target cells. The highest transduction efficiency was obtained at a multiplicity of infection (MOI) rate of 500 (AP + DCs: 50 +/- 2%, viability =95%) under both small- and large-scale conditions. The addition of poly-L-lysine or LipofectAmine increased the percentage of transduced cells at an MOI of 500 (CD1a+/AP+ cells = 85 +/- 3% and 80 +/- 2% respectively). Polycations made it possible to reduce the amounts of viral particles, with high efficiency of transduction being achieved at a MOI of 100 with 10 microg/ml poly-L-lysine (CD1a+/AP+: 68 +/- 9%) or 30 microg/ml LipofectAmine (CD1a+/AP+: 60 +/- 7%). Evaluation of the immunophenotype of the transduced DCs showed that the lack of a DC subpopulation was more susceptible to adenoviral transduction. Cryopreservation of transduced DCs did not modify the viability or percentage of AP+ cells that maintain antigen-presenting cell (APC) functions. These findings indicate the efficacy of this method for the transduction of large amounts of CD34+ cell-derived DCs using small quantities of adenoviral vector mixed with polycations. Cryopreservation of transduced DCs did not damage their viability or APC functions, thus making it possible to plan multiple injections of engineered DC-based vaccines.

Preparation, morphological characterization, and activity of thin films of horseradish peroxidase

Active uniform films of horseradish peroxidase (HRP) have been prepared by covalent binding on Si/SiO(2) or glass supports previously activated by silanization and succinylation. Labeling by fluorescent or by Electron Spin Resonance (ESR) probes was used to quantify the surface density of active groups and of horseradish peroxidase. Atomic Force Microscopy (AFM) imaging was used to characterize the surface morphology. We observed that a non-uniform protein adsorption due to physical interactions was present when the supports were not activated for covalent binding and was, in large part, removed by washing. The enzyme deposited by covalent binding formed homogeneous layers with a height in the range 60-90 A. By using a fluorescent label, we calculated a protein density of 3.6 x 10(12) molecules cm(-2) on Si/SiO(2), corresponding to an estimated area per molecule of 2800 A(2) which is in agreement with the value expected on the basis of the crystallographic data considering the formation of a monomolecular layer. The protein density of the layer immobilized on glass was similar (1.9 x10(12) molecules cm(-2)). The enzyme immobilized on both supports showed a k(cat)/K(M) being of the order of 3-5x10(5) M(-1)s(-1) that is 1/20th of free HRP. The half-life time of the activity of the enzyme immobilized by covalent binding was longer than 40 days at 6 degrees C.

Contribution of proanthocyanidins to the peroxy radical scavenging capacity of some Italian red wines

Highly reactive radicals, ROO(*), were generated from 2, 2'-azobis[2-(2-imidazolin-2-yl)propane] and linoleic acid. The ROO(*) scavenging capacity of some Italian red wines was evaluated following the changes in oxygen consumption. Under the experimental conditions the time course of oxygen consumption shows two typical behaviors: trolox-like (class I) and gallic acid-like (class II). Usually the time course of wine was similar to that of gallic acid. The rate of oxygen consumption was found to decrease exponentially with the amount of wine or gallic acid added to the test solution. On this basis the capacity of red wines to scavenge peroxy radicals was expressed as content of gallic acid (S(GA)). The S(GA) values were found to be correlated to the amount of total proanthocyanidins and total polyphenols of some Italian red wines (p < 0.01). The proanthocyanidins extracted from seeds were shown to make a major contribution to the peroxy radical scavenging capacity of red wines, whereas, interestingly, the chemical class of the low molecular weight tannins reactive to vanillin did not correlate with the S(GA) values.

Enzyme mimics complexing Cu(II) ion: structure-function relationships

Five peptides containing (His-X2)-His or (His-X3)-His motifs have been designed and synthesized to coordinate Cu(II). Structural information was obtained by various spectroscopic techniques and was used as constraint to search for local conformational energy minima by molecular mechanics. Thermodynamic stability constants of the Cu(II) chelates was obtained by 19F-NMR. The synthesized Cu(II)-peptide chelates were tested as catalysts of some important red-ox processes occuring in biological systems, in particular oxidation of ascorbate and dismutation of superoxide ion. The catalytic efficiency of the five chelates was much lower than that of ascorbate oxidase. On the contrary, two of them showed kinetic constants for superoxide dismutation about one order of magnitude lower than that of the enzyme Cu,Zn superoxide dismutase. In both cases, the catalytic properties were dependent on the peptide sequence. The relationships between structure and activity are discussed to find the structural parameters crucial for catalytic activity that can be modulated by appropriate design and synthesis of the peptides.

Polyethylenimine shows properties of interest for cystic fibrosis gene therapy

Before being considered for a cystic fibrosis (CF) gene therapy trial, any gene delivery agent must be able to show that it produces low levels of toxicity as well as being able to protect the DNA from nuclease degradation. Here we show that complexes of linear polyethylenimine (L-PEI) and DNA can repeatedly be administered to animals (up to 21 consecutive days) without eliciting an immune response against PEI/DNA particles or inducing toxic side effects due to accumulation of PEI in the lungs. However, the host response to the exogenous protein resulted in some decrease of expression. PEI-mediated transfection was unaffected by treatment of the complexes with DNase (frequently used to reduce the viscosity of lung secretions in CF patients). Taken together, these properties make L-PEI a valuable vector for gene therapy of CF.

Recombinant adenoviral vector-lipofectAMINE complex for gene transduction into human T lymphocytes

We have evaluated, as a vector for gene transfer into human T lymphocytes, a recombinant adenovirus (rAd-MFG-AP) carrying a modified, membrane-exposed, alkaline phosphatase (AP) as reporter gene. CD3+ cells were selected from the buffy coat of healthy donors by the immunomagnetic technique. The positive cell population, comprising 96+/-2% CD3+ cells, was cultured with clinical-grade cytokine(s) for 3-7 days prior to rAd-MFG-AP transduction and the transgene expression was evaluated 48 hr later by indirect immunofluorescence flow cytometry assay with an anti-alkaline phosphatase antibody. The best efficiency of transduction was achieved on incubation of CD3+ cells with IL-2 plus either IL-12 (AP+ cells, 12+/-3%) or IL-7 (AP+ cells, 11+/-3%). To increase further the efficiency of transduction, we have combined LipofectAMINE and rAd-MFG-AP with the aim to enhance the uptake of viral particles into the target cells. The percentage of CD3+ cells transduced by rAd-MFG-AP-LipofectAMINE complex was 24+/-4% (range, 20-35%) after incubation with IL-2 plus IL-7 and 22+/-4% (range, 18-32%) after incubation with II-2 plus IL-12. Forty-eight hours after the incubation with rAd-MFG-AP, the transduced T lymphocytes were subjected to fluorescence-activated cell sorting and fractionated into AP+ and AP- cell subpopulations. The AP+ cell fraction, comprising 96.8% of AP+ cells, was evaluated by FACScan analysis for T lymphocyte surface antigens. The immunophenotyping of the transduced T lymphocytes has shown that there was not a particular subtype of T lymphocytes more susceptible to rAd-MFG-AP transduction. In addition, the transgene expression did not modify T lymphocyte functions, as demonstrated by results obtained by cytotoxicity assay before and after rAd-MFG-AP-LipofectAMINE complex transduction. In conclusion, human T lymphocytes can be efficiently transduced, under clinically applicable conditions, by adenovirus-LipofectAMINE complex after 7 days of culture with IL-2 and IL-12 or IL-7.

Detection of five rare cystic fibrosis mutations peculiar to Southern Italy: implications in screening for the disease and phenotype characterization for patients with homozygote mutations

BACKGROUND

The search for the eight most frequent mutations (i.e., DeltaF508, G542X, W1282X, N1303K, 1717-1G-->A, R553X, 2183AA-->G, and I148T) by allele-specific oligonucleotide dot-blot analysis revealed 78% of 396 cystic fibrosis alleles in Southern Italy. The observation of frequent haplotypes on the unidentified cystic fibrosis alleles suggested that a few mutations could account for a large number of unidentified alleles.

METHODS

We screened most of the coding sequence of the cystic fibrosis transmembrane regulator gene by denaturing gradient gel electrophoresis to determine the spectrum of these mutations in 68 unrelated cystic fibrosis patients bearing one or both unidentified mutations.

RESULTS

The screening revealed five mutations, R1158X, 711+1G-->T, 4016insT, L1065P, and G1244E, each of which had a frequency of 1.3-1.8% (7% collectively). The 7% increase in the detection rate (85% vs 78%) reduces by >50% the residual risk of being cystic fibrosis carriers for couples who had tested negative by molecular analysis. We therefore designed a second allele-specific oligonucleotide set to analyze the five mutations. Among the patients analyzed, one patient homozygous for the L1065P mutation expressed a mild pulmonary and intestinal form of the disease with pancreatic insufficiency. Two other patients, homozygous for mutations R1158X and 4016insT, both expressed a severe cystic fibrosis phenotype.

CONCLUSIONS

Five cystic fibrosis mutations are peculiar to patients from Southern Italy. The method described for their analysis is efficient, inexpensive, and can be semi-automated by use of a robotic workstation. The results obtained in patients from Southern Italy may have an impact on laboratories in other countries, given the large migrations of populations from Southern Italy to other countries in the last two centuries.

A rat brain fraction and different purified peroxidases catalyzing the formation of dopaminochrome from dopamine

Dopaminochrome formation is catalyzed by commercially available purified peroxidases (EC 1.11.1.7) such as horseradish, lacto- and myelo-peroxidase using dopamine, hydrogen peroxide or promethazine sulfoxide as substrates. A rat brain fraction (RBF) catalyzes a similar reaction and its catalytic power increases after preincubation with hydrogen peroxide/ascorbic acid. The activity of both the purified enzymes and the RBF preparation is inhibited by carnosine and characterized by excess substrate inhibition. The enzymes recognize different substrates but show the highest affinity for dopamine. The RBF fraction is strongly buffered against oxidation by compounds such as glutathione and by bioreductive enzymes such as DT-diaphorase (EC 1.6.99.2) which can use as a substrate menadione or dopaminochrome. The rat brain dopamine peroxidizing activity appeared to be mostly bound to the synaptosomal fraction. The reaction catalyzed by the purified peroxidases was followed by electron spin resonance spectroscopy and, unlike that catalyzed by RBF, was shown to produce the signal of a transient dopamine-o-semiquinone radical.

An ESR assay for alpha-amylase activity toward succinylated starch, amylose and amylopectin

The esterification of the three polysaccharides, starch, amylose and amylopectin was carried out in pyridine-DMSO by succinic anhydride. The carboxylic groups in the succinylated polysaccharides were measured by FT-IR spectroscopy. The succinic derivatives were tested as alpha-amylase (1,4-alpha-D-glucan glucano hydrolase, E.C. 3.2.1.1) substrates. A colorimetric assay of the alpha-amylase activity indicated that this enzyme is active on succinic esters of starch and amylose and that the activity shows a linear decrease with the number of succinic units introduced into the polysaccharide. Since the colorimetric test was not suitable for the detection of the alpha-amylase activity when succinylated amylopectin was the substrate, we set-up an assay based on the labeling by a paramagnetic probe of the free carboxylic groups of succinylated polysaccharides. The kinetics of the alpha-amylase reaction were monitored by ESR spectroscopy through the increase of the mobility of the paramagnetic probe. The spin label used was the commercially available 4-amino-tempo. By this method we demonstrated that alpha-amylase is active on succinylated amylopectin. The utility of the assay for monitoring alpha-amylase activity when other methods (i.e. colorimetric tests) fail, is discussed.

Continuous flow immunosensor for atrazine detection

The hapten atrazine was detected under continuous flow conditions using a micro-column which contained immobilized monoclonal antibodies (Ab) against atrazine and atrazine labeled with alkaline phosphatase (An*). The equilibrium of the antibody-hapten system, was achieved by a continuous flow of the tracer An* through the micro-column containing the immobilized antibodies. The activity of the tracer was monitored continuously, after the micro-column, by an amperometric detector using p-hydroquinone phosphate as substrate. When pulses of unlabeled atrazine (An) were added to the An* flowing continuously through the micro-column, An* bound to the antibody was displaced, with a consequent change of the detector signal. By this method atrazine concentrations in the range 9-180 micrograms/l were monitored under conditions of continuous operation. Since the equilibrium condition for the system Ab-An* was continuously restored by the flow of An* through the micro-column the regeneration of the antibody was not required.

In vitro and in vivo antitumor effects of retrovirus-mediated herpes simplex thymidine kinase gene-transfer in human medulloblastoma

Herpes simplex virus thymidine kinase gene (HSVtk) transfer together with treatment with the prodrug ganciclovir (GCV) represents the most commonly used suicide gene approach for the gene therapy of human central nervous system malignancies. Despite encouraging results reported in clinical trials conducted in adults, very little is known about the feasibility of this approach for the treatment of CNS tumors of childhood. We studied the effects of the HSVtk/GCV system on human medulloblastoma cells in vitro and in vivo. The transfer of tk gene to medulloblastoma cells was capable of mediating cell suicide in vitro and in vivo upon treatment with GCV, but the overall effect in vivo appeared to be suboptimal. The relatively low sensitivity of the medulloblastoma cells to viral infection and a limited bystander effect, coupled with a low expression of connexin-43 protein, might partially explain these results. Whether this is a peculiarity of the cell line studied or a general characteristic of medulloblastoma remains to be determined. These findings should be taken into account for the future planning of gene therapy trials for human medulloblastoma.

A peroxidase-catalyzed sulfoxidation of promethazine

Lactoperoxidase, when incubated with increasing amounts of promethazine (P) and promethazine sulfoxide (PO) catalyzes the formation of promethazine sulfoxide accompanied by oxygen consumption. An intermediate radical of PO can be detected by electron spin resonance (ESR). Catalase or superoxide dismutase do not inhibit the reaction while dopamine does. The lactoperoxidase-catalyzed formation of dopaminochrome in the presence of hydrogen peroxide is inhibited by P. Both P and PO inhibit acetyl- and butyrylcholinesterase. Purified enzymes were used throughout the study and horseradish peroxidase but not myeloperoxidase had an activity similar to that of lactoperoxidase.

An automated method for mapping human tissue permittivities by MRI in hyperthermia treatment planning

This paper presents an automatic method to obtain tissue complex permittivity values to be used as input data in the computer modelling for hyperthermia treatment planning. Magnetic resonance (MR) images were acquired and the tissue water content was calculated from the signal intensity of the image pixels. The tissue water content was converted into complex permittivity values by monotonic functions based on mixture theory. To obtain a water content map by MR imaging a gradient-echo pulse sequence was used and an experimental procedure was set up to correct for relaxation and radiofrequency field inhomogeneity effects on signal intensity. Two approaches were followed to assign the permittivity values to fat-rich tissues: (i) fat-rich tissue localization by a segmentation procedure followed by assignment of tabulated permittivity values; (ii) water content evaluation by chemical shift imaging followed by permittivity calculation. Tests were performed on phantoms of known water content to establish the reliability of the proposed method. MRI data were acquired and processed pixel-by-pixel according to the outlined procedure. The signal intensity in the phantom images correlated well with water content. Experiments were performed on volunteers' healthy tissue. In particular two anatomical structures were chosen to calculate permittivity maps: the head and the thigh. The water content and electric permittivity values were obtained from the MRI data and compared to others in the literature. A good agreement was found for muscle, cerebrospinal fluid (CSF) and white and grey matter. The advantages of the reported method are discussed in the light of possible application in hyperthermia treatment planning.

ExGen 500 is an efficient vector for gene delivery to lung epithelial cells in vitro and in vivo

Nonviral vectors might represent a safe alternative to adenovirus for gene therapy of lung disorders, in particular cystic fibrosis (CF). Cationic lipids have been shown to correct the CF defect both in vitro and in vivo, but more efficient vectors are needed to improve the low gene transfer efficiency. Here, we show that the cationic polymer ExGen 500, a linear polyethylenimine derivative, is more efficient than cationic lipids in transferring reporter genes to lung epithelial cells in vitro. In vivo ExGen 500 was able to mediate gene transfer into both newborn and adult rabbit lungs with comparable efficiencies. The best levels of transfection were obtained using neutral complexes. Under such conditions, luciferase activities corresponding to about 10(3) RLU/10 s/mg of protein were reproducibly obtained 2 days after transfection throughout the four lung lobes of newborn and adult rabbits. A nlslacZ reporter gene showed transfected cells around the lumen of large and small bronchi. No signs of acute toxicity (inflammation, cellular infiltration etc) were detected by direct histopathological analysis. Within 1 week after instillation, transgene expression decreased by two orders of magnitude.

Deuterium distribution in lactate as tracer of metabolic pathways

2H-NMR spectroscopy has been used to study the distribution of 2H atoms in brain lactate, after intraperitoneal injection of 2H2O. Information on brain metabolism was obtained from the ratio [(3-2H) lactate]/[(2-2H)-lactate] which was found very sensitive to the PO2 in the breathing air. The dependence of this ratio on the rates of metabolic pathways is an example of the possibility to use the distribution of 2H atoms in a molecule to probe metabolic flow through different pathways.

The bacteriophage T7 binary system activates transient transgene expression in zebrafish (Danio rerio) embryos

The bacteriophage T7 binary expression system is widely used in vitro for high level selective expression of cloned genes but its application to in vivo models has not yet been investigated. In the present work, we show that coinjection into fertilized zebrafish eggs of pE1T7R, an expression plasmid bearing the T7 RNA polymerase gene driven by the cytomegalovirus (CMV) promoter, together with reporter vectors containing the Escherichia coli lacZ gene driven by the T7 promoter, resulted in the efficient expression of the reporter gene in 24-h mosaic transgenic embryos. Conversely, embryos receiving an unrelated CMV-expression plasmid, instead of pE1T7R, lacked significant reporter gene activity, indicating the strict requirement of T7 polymerase to activate the T7 promoter in these embryos. The present study demonstrates the possibility of applying efficiently the bacteriophage T7 binary system in vivo to a vertebrate model.

Development and characterization of a binary gene expression system based on bacteriophage T7 components in adenovirus vectors

To explore the utility of the bacteriophage T7 binary system in adenovirus (Ad) vectors we constructed three Ad5-based vectors containing the T7 RNA polymerase (T7pol) gene in either early region 1 (E1) or E3. The recombinant Ad vectors were either deficient (AdT7pol1, AdT7pol2) or competent (AdT7pol3) for replication in human cells other than Ad5 transformed (293) cells. To test the ability of the T7 polymerase produced by these vectors to drive gene expression, a reporter vector was constructed with an E1 substitution comprising the bacterial beta-galactosidase (betaGal) (lacZ) gene under the control of the T7 gene 10 promoter (T7pro) and linked to the encephalomyocarditis virus (EMCV) internal ribosome entry site (IRES) (AdBHG10T7betaGal). Coinfections were performed with the various AdT7pol vectors and the reporter vector, and expression was analysed in three different human cell lines: 293, A549 and MRC-5. Depending on the AdT7pol vector used, different levels of expression were obtained from the reporter gene. In 293 cells, expression was detected following infection at very low multiplicities of infection (moi) with all of the T7pol vectors when coinfected with the reporter vector AdBHG10T7betaGal. In A549 and MRC-5 cells very little expression was detected using AdT7pol1 or pol2 and efficient expression was only obtained when relatively high moi values of the replication-competent vector were used in the coinfections. We also constructed a single vector containing both elements of the T7 system (T7pol in E3 and T7 promoter driving expression of the chloramphenicol acetyl transferase (cat) gene in E1). This vector proved difficult to rescue but was stable once isolated. Finally, experiments performed to evaluate the 'leakiness' of the Ad-T7 system detected very little expression from the T7pro in the absence of T7 polymerase suggesting this system may be useful for the cloning and expression of genes encoding cytotoxic proteins.

Learning and forgetting processes in Parkinson's disease: a model-based approach to disentangling storage, retention and retrieval contributions

Learning and forgetting a prose passage was studied in 20 patients with Parkinson's disease and in 20 normal control subjects by means of stochastic models, with the aim of identifying the learning and retaining abilities that are affected by Parkinson's disease. Results suggested that Parkinson's disease patients are impaired in developing automatic processing both during learning and retaining, while functions that require active attention are spared. The automatic/intentional dissociation, which is the hallmark of motor disturbance in Parkinson's disease, extends to memory abilities, and, on the grounds of neuroanatomical, neurochemical and neurophysiological correlates, suggests that the memory deficit in Parkinson's disease may be contingent on a dysfunction of the medial prefrontal-cingulate cortex.

In vitro correction of iduronate-2-sulfatase deficiency by adenovirus-mediated gene transfer

Hunter syndrome is a lethal lysosomal storage disorder caused by the deficiency of iduronate-2-sulfatase and characterized by severe skeletal and neurological symptoms. Only symptomatic treatments are available and, although bone marrow transplantation has been suggested, no encouraging results have been obtained so far. Therefore, gene therapy might be a route to be pursued for treatment of the disease. In this respect, one major goal to achieve is the generation of an overexpressing vector able to correct, in particular, central nervous system (CNS) cells. Adenoviruses have been shown to infect CNS cells efficiently with minor or even absent immunological response. We describe the generation of a replication-defective adenoviral vector, AdRSVIDS, which is able to express in vitro high levels of iduronate-2-sulfatase. After infection, accumulation of mucopolysaccharides in treated Hunter cells was normalized. Furthermore, endocytosis of the transduced IDS did occur via the mannose-6-phosphate (M6P) receptor. Since no animal model for the disease is available, we developed a system based on the generation of derma-equivalents which enabled us to verify the expression of high levels of sulfatase up to 30 days after infection.

[Ureteroscopic lithotripsy using the laser]

The Cagliari urology team is very satisfied with the use of the dye laser for ureteroscopic lithotripsy. This apparatus is recommended in units possessing a well equipped endourology room, otherwise it is simpler to use endoureteric ballistic lithotripsy, which also provides good results.

In vitro and in vivo gene transfer to pulmonary cells mediated by cationic liposomes

Cationic liposomes have been proposed as alternative to adenovirus in the treatment of cystic fibrosis lung disease. Therefore, we have investigated the efficiency of two lipid mixtures in mediating gene transfer in in vitro and in vivo models. The cationic lipid DOTMA (N-(1-(2,3(dioleyloxy)propyl)-n,n,n-trimethylammoniumchloride++ +) and DOGS (dioctadecylamidoglycylspermine) were used in combination with the neutral lipid DOPE (dioleoylphosphatidylethanolamine). The relative transfection efficiencies of the two cationic liposomes were tested using the bacterial beta-galactosidase (lacZ) and the firefly luciferase genes. Gene expression was detected in both cell limes and primary culture of rhesus monkey airway epithelium after transfection with plasmid DNA complexed with DOGS/DOPE or DOTMA/DOPE. Transfection efficiency of both types of lipids was higher in the mouse fibroblast 3T3 cell line as compared to human carcinoma A549 cells and primary epithelial cultures. Administration of DNA-liposome complexes via intratracheal instillation resulted in expression of the lacZ and luciferase marker gene in the mouse airways. In vivo transfection mediated by both types of liposomes were proven to be far less efficient than adenovirus treatment.

Horseradish peroxidase-catalyzed sulfoxidation of promethazine and properties of promethazine sulfoxide

Promethazine sulfoxide was obtained with a quantitative yield in a horse radish peroxidase-catalyzed reaction of promethazine and hydrogen peroxide and was also prepared by direct chemical synthesis. The enzymatic sulfoxidation of promethazine was studied in vitro as a function of pH, promethazine, and hydrogen peroxide concentration. Promethazine sulfoxide inhibits with an apparent K(i) of 59.7 microM at pH 5.5 the enzymatic reaction, followed spectrophotometrically, polarographically, potentiometrically, and luminometrically. The reaction was also inhibited by ascorbic acid (K(i) 26.8 microM) and glutathione (K(i) 41.8 microM). The spectrophotometric techniques employed, together with ESR spectrometry, allowed the identification of at least three radical species formed in the course of the reaction. Promethazine sulfoxide is devoid of the antioxidant effect exhibited by promethazine on rat brain synaptosomes. The sulfoxide also lacks photosensitizing action, while retaining the neuroleptic effect of the parent compound.

Parkinson's disease affects automatic and spares intentional verbal learning. A stochastic approach to explicit learning processes

We studied word list and paired associates learning in patients with idiopathic Parkinson's disease and normal controls by means of a two-stage stochastic model, which allows independent measurements of encoding, storage and retrieval abilities. We preliminarily ascertained that the model components were both sufficient and necessary to account for the overall performance of the subjects, and then compared the learning abilities between the two groups. Parkinson's disease patients were selectively impaired in identifying well-known engrams, for which learning is superfluous, and in automatic retrieval, namely in abilities that do not need attentional effort. By contrast, they were unimpaired in encoding and intentional retrieval, which require a purposeful effort. The automatic-voluntary dissociation of Parkinson's disease patients' motor behaviour is, therefore, paralleled by some features of their memory performance.

A brain-damaged patient with an unusual perceptuomotor deficit

When interacting with objects, the pattern of movements is influenced by such object characteristics as size and position. Little is known about the effect of higher level categorical encoding of objects upon movements. Here we present evidence for an approval-for-action process which takes into account such encoding. For the brain-damaged subject L.P., the ability to complete actions involving two objects in central vision is influenced by the semantic or functional relationship between the objects. Even though she perceives only one object, she can integrate two related objects into a coordinated action. If the objects are not related she is unable to integrate them into a single motor act. We propose that selection-for-action systems include processes which gate conceptually the behavioural disposition to action.

Effect of polyphosphates on the activity of amine oxidases

The interaction between polyphosphates and polyamines was investigated by 31P-NMR spectroscopy and by amine oxidase activity measurements. An apparent competition between negatively charged polyphosphates (ATP, ADP, AMP, tripolyphosphate and pyrophosphate) and positively charged polyamine, for the active site of bovine serum and soybean seedling amine oxidases, was observed by activity measurements. This behavior was explained by formation of polyamine-polyphosphate complexes and the stability constants of these complexes were calculated by 31P NMR. However, at a given concentration of polyphosphate, the amine oxidase activity was found higher than that expected on the basis of the free amine concentration calculated according to the NMR stability constant. This fact, and the different extent of inhibition of the spermidine oxidase activity of soybean seedling and of bovine serum amine oxidases observed in the presence of a given polyphosphate, suggest that amine oxidases may be active also on the polyamine-polyphosphate complexes. This hypothesis was supported by the strong dependence of the kcat/Km of bovine serum amine oxidase on ionic strength, indicating an electrostatic interaction between the charged amine and the active site, while no effect of ionic strength on kcat/Km was observed in the presence of ATP. A kinetic model of this behavior was found to fit the experimental data.

Covert visuospatial attentional mechanisms in Parkinson's disease

Orienting and focusing of attention were assessed in 32 Parkinson's disease and 32 control subjects. No differences were found in the covert orienting of attention, suggesting that the Parkinson's disease subjects of the current study were not impaired in the ability to orient attention towards an expected source of stimulation. However, with the process of modulating the attentional focus or of managing more than one attentional task, dysfunction in Parkinson's disease subjects became apparent. The observed results are explained in terms of deficits in the relationship between task-related distribution of attentional resources and time efficiency of processing.

Kinetics of nitroxide spin label removal in biological systems: an in vitro and in vivo ESR study

A systematic study on the disappearance of the electron spin resonance (ESR) signal of nitroxides based on six-or five-membered ring and bearing various charges was carried out in vitro and in vivo. The second-order kinetic rate constants of the reaction of spin probes with ascorbate were measured in vitro at various temperatures in phosphate buffered saline, and the relative activation energies were calculated. Clearance rates of the nitroxide radicals in rat brain homogenates and in blood indicate that the ascorbate contribution to nitroxide removal is about 50-70% in brain and 50-90% in blood. These rates can be easily calculated on the basis of the ascorbate concentration and of the second-order kinetic rate constants measured in phosphate buffered saline. ESR spectra acquired in vivo in rat head and tail, by an L-band resonator, indicated that the nitroxide decay rate is a first-order kinetic process in both domains and that the positively charged nitroxides are not retained in the brain, whereas the anionic and uncharged nitroxides are. Once nitroxides with piperidine ring enter the brain, their decay appears controlled mainly by ascorbate, while the ascorbate has a negligible influence on disappearance in brain of five-membered ring proxyl nitroxides.

Antiretroviral activity of furocoumarins plus UVA light detected by a replication-defective retrovirus

The replication defective retrovirus, pXM5(N2), was used for an easy, safe and reproducible test for the screening of furocoumarins with antiretroviral activity. High titer viral supernatants have been photomodified by UVA light (20 kJ m-2) in the presence of different concentrations of two psolarens (8-methoxypsoralen, 8-MOP and 4,5',8-trimethylpsoralen, TMP) and one angelicin (4,6,4'-trimethylangelicin, TMA). At low concentrations (100-250 ng ml-1) 8-MOP and TMA did not show any significant antiviral activity, while TMP demonstrated a reduction of virus infectivity by one log at 250 ng ml-1. At the highest concentration (5 micrograms ml-1), TMA and TMP reduced the virus titer by one and more than two logs, respectively, being, therefore, two and four times more active than 8-MOP. The most active compound, TMP, was further tested on HIV-1 viral supernatants. Total inactivation of the HIV-1 (200 SFU) was obtained in the presence of 1 microgram ml-1 of TMP and 20 kJ m-2 of UVA light. Our results support the validity of the N2 system to detect the antiretroviral activity of furocoumarins and suggest the potential of TMP in combination with UVA light against HIV-1.

Perturbation of a prehension movement in Parkinson's disease

Movement kinematics of the transport and manipulation components of a double-step prehension task were studied in eight Parkinson patients and eight control subjects. The aims were to (a) assess the effects of a spatial perturbation upon the movement for the two groups and (b) add data to the controversy about the damage/preservation of predictive behaviour in Parkinson patients. The results showed: (a) Both groups are able to preprogram a movement. (b) In both groups, the perturbation results in an anticipation of all kinematic parameters, both of the transport and manipulation components. (c) Parkinson patients, when adopting a predictive behavior, show a delay between the beginning of the two components, and thus activate them in sequence rather than simultaneously. This delay is significantly reduced by the perturbation, indicating that Parkinson patients, when using a responsive behavior, can recouple the two motor components.

Electrostatic control of oxidative deamination catalysed by bovine serum amine oxidase

The ionic-strength-dependence of steady-state kinetic parameters (kc and Km') for non-biogenic (benzylamine, butylamine) and biogenic (spermine, spermidine) amines has been measured in the bovine serum amine oxidase reaction. The catalytic rate constant (kc) values are similar (0.9-2.5 s-1) for all the substrates studied and are almost constant over the experimental ionic strength range (24-155 mM). In contrast, Km' values are in the range 6-2300 microM and undergo a 4-12-fold increase with increasing ionic strength, parallelled by a decrease in catalytic efficiency. From an analysis of the kc and Km' values and their dependence on ionic strength, we conclude that more than one negative site is involved in the binding of these amines and that the relative dielectric constant of the binding site is lower than that of aqueous solutions.

A sensitive spectrophotometry-based method for the determination of the rate of hydrogen peroxide generation in biological systems

A new sensitive spectrophotometric method for the determination of the rate of hydrogen peroxide generation in biological systems has been developed. This method is based on the measurement of the oxidation rate of reduced cytochrome c by H2O2 in the presence of a mediator and permits the detection of H2O2 generation rates as low as 60 nM min-1. The solution of the differential equations of the kinetic process permitted the calculation of the kinetic rate constants and assessment of the conditions required to measure the hydrogen peroxide generation rate.

Gene transfer in regenerating muscle

We have compared the efficiency of direct gene transfer in normal and regenerating rat skeletal muscle. Muscle necrosis and regeneration was induced by intramuscular injection of bupivacaine in the soleus muscle of adult rats. Plasmids containing beta-galactosidase (beta-gal) or chloramphenicol acetyltransferase (CAT) genes driven by viral promoters were injected 3 days after bupivacaine treatment into the regenerating and the contralateral uninjured muscles. Expression of CAT activity was > 80-fold higher in regenerating compared to control muscles at 7 days post-transfection, but decreased at 30 and 60 days. Southern blot analysis showed that the predominant form of CAT DNA was episomal in transfected muscles; however, CAT activity measurements performed on the same transfected muscles showed no precise correlation between enzymatic activity and amount of plasmid DNA. Expression of beta-gal was detected in numerous regenerating fibers of the injured soleus muscles at 7 days post-transfection; in contrast, only rare positive fibers were found in control muscles. Focal infiltrates of mononuclear cells, which surround and invade selectively beta-gal-positive fiber segments, were observed at 30 days post-transfection, suggesting that immune mechanisms are implicated in the progressive loss of transgenes with time. The finding that regenerating muscle fibers display a higher efficiency of transfection may be relevant to gene therapy of Duchenne muscular dystrophy, because regenerating fibers are numerous in the early stages of the disease.

Uptake and life time of fluoride ion in rats by 19F-NMR

19F nuclear magnetic resonance (NMR) was utilized to obtain information on the uptake and half-life time of fluoride ion in rats. Changes in tissue fluoride level after acute loading were monitored over time in blood and tissue homogenates obtained from liver and brain. The rate of fluoride elimination from various tissues was roughly similar, following in all cases a first-order kinetic rate law. The F- concentration in brain was about 20% of that found in liver, indicating a reduced fluoride diffusion across the blood-brain barrier. In vivo F- spectra were obtained in rat brain in few minutes with a good signal-to-noise ratio; this confirms the possibility of extending the use of F- as a probe of biomolecules to in vivo applications.

Effect of phosphate ion on the activity of bovine plasma amine oxidase

The system bovine plasma amine oxidase-polyamine-phosphate ion was investigated by activity measurements and 31P NMR spectroscopy. Lineweaver-Burk plots showed that phosphate ion, under physiological conditions, is an apparent competitive inhibitor of bovine plasma amine oxidase. While NMR measurements of the T1 of 31P do not suggest the binding of phosphate to/or near the paramagnetic Cu(II) sites of bovine plasma amine oxidase, the chemical shift dependence of 31P on spermidine concentration indicates the formation of a spermidine-phosphate complex. The value of the dissociation constant of this complex was found 18.5 +/- 1.4 mM, at pH 7.2, by NMR, in good agreement with the value 17.0 +/- 0.8 mM calculated from activity measurements, assuming the enzyme activity is proportional to the free amine concentration, under second order conditions. Our data suggest that the decrease of the free spermidine, due to the binding of phosphate ion, is responsible of the observed inhibition of bovine plasma amine oxidase.

Added ATP influences some responses of rat synaptosomes to glutamate

ATP added externally to rat synaptosomes activated uptake of both Ca2+ and glutamate which was partially accounted for by the uptake phenomena of synaptic vesicles and mitochondria, as shown by using specific inhibitors of the latter. Increasing concentrations of glutamate stimulated Ca2+ entry linearly, as shown by using 45Ca or a Ca-specific electrode. The processes of glutamate and Ca2+ uptake shared some common features and their ATP-dependence may be correlated with an ouabain-insensitive synaptosomal ectonucleotidase activity measured by a 31P-NMR or a luminometric technique. The ATP hydrolysis catalysed by the synaptosomes was activated by both Ca2+ and glutamate. The present synaptosomal activities may represent a model for studying the modulatory effects of ATP on the glutamatergic neurotransmission.

Temporal coupling between transport and grasp components during prehension movements: effects of visual perturbation

The temporal coupling between the transport and grasp components of prehension movements was investigated through two experiments. In Experiment 1, six normal subjects were required to reach and grasp each of three spheres located at three different distances (Blocked trials). In Experiment 2, a visual perturbation paradigm was used in which the location of the object to be reached and grasped could change at the beginning of arm movement (Perturbed trials). The same subjects participated in both experiments. Kinematics of wrist trajectory (transport component) and of distance between thumb and index finger (grasp component) were analyzed. The results of Experiment 1 showed that the two components could be temporally coupled during their time course. In Experiment 2, the visual perturbation affected both the components, but different times were required by each component to reorganize the movement towards the new target. These different times caused the decoupling of those events that appeared synchronized in Experiment 1. Finally, evidence was found to suggest that planning of grip formation takes into account not only the perceived characteristics of the object, but also the time planned by the transport component to reach the object.

ATP-stimulated glutamate-dependent calcium uptake by rat synaptosomes

The entry of Ca2+ in rat synaptosomes was followed with a Ca(2+)-selective electrode. Extracellular ATP is necessary for the entry which is a function of synaptosomal protein, free Ca2+ and glutamate concentrations. Ketamine, glycine and kainate have negligible effect while quisqualate slightly inhibits the uptake of Ca2+ in the presence of glutamate. The added ATP is hydrolyzed by the synaptosomes through an ouabain-insensitive ecto-ATPase affected by the presence of Ca2+, glutamate and, to a slight extent, NMDA.

Screening for cystic fibrosis gene mutations by multiplex DNA amplification

We have developed a simple rapid DNA screening test that allows us simultaneously to analyze seven CF mutations (delta F508, R347P, S549N, G551D, R553X, R334W, 444delA) that together account for about 60% of all CF mutations in the Italian population. It consists of three steps: multiplex polymerase chain reaction (PCR) amplification of exons 4, 7, 10 and 11; restriction endonuclease digestion of the PCR products; and vertical polyacrylamide gel electrophoresis analysis. We have used our multiplex assay for analyzing 15 CF chromosomes (non delta F508) and have found 3 cases of the R553X mutation; the latter have been confirmed by amplification and digestion of exon 11.

A model-based study of learning and memory following transient global amnesia attacks

Verbal learning and forgetting were studied in patients one month after an episode of Transient Global Amnesia and in normal control subjects by means of a two-stage stochastic model, which allows independent measurements of encoding, storage and forgetting. We preliminarily ascertained both the necessity and the sufficiency of the model to account for several performance scores of the two experimental groups, and then compared the learning and forgetting functions between groups. In spite of the analytical power of the statistical method adopted. Transient Global Amnesia was not found to entail persistent impairment of encoding and storage, as well as of retaining memory traces and retrieval algorhythm.

Evaluation of lymphoid-specific enhancer addition or substitution in a basic retrovirus vector

Two novel retroviral vectors bearing lymphoid-specific enhancers were tested for improved expression of human adenosine deaminase (hADA) in tissue culture cells and in mouse bone marrow transplant recipients. These vectors carried either an added human T-cell receptor alpha-chain enhancer (delta N2TADA) or a substitution of the Moloney long terminal repeat (LTR) enhancer with the murine immunoglobulin mu heavy-chain first intron enhancer (delta N2 mu ADA). Each vector was produced at a titer of approximately 10(6) infectious units/ml and efficiently transduced hADA into murine fibroblast and myeloma cells in culture. No quantitative difference in expression was observed between the enhancer modified vectors and the basic retrovirus vector (delta N2ADA). In addition, each vector efficiently conferred hADA expression in lymphoid, myeloid, and erythroid cells of long-term transplanted mice. The majority of the transduced-marrow recipients demonstrated expression of the human enzyme for 4-8 months with each of the three vectors.

Gene transfer of adenosine deaminase into primitive human hematopoietic progenitor cells

The inherited deficiency in adenosine deaminase (ADA), which results in severe combined immunodeficiency, is generally regarded as an optimal model for the development of human somatic gene therapy. The ideal target for the correction of ADA deficiency and other lympho-hematopoietic disorders would be the hematopoietic stem cell. We have used a combination of recombinant human interleukins-3 and -6 to stimulate the proliferation of primitive human hematopoietic progenitor cells during a period of co-cultivation with irradiated cells producing high titers of an ADA-transducing retroviral vector packaged in amphotropic particles. In a series of nine experiments, an average of 83% of the clonogenic progenitors (CFU-E and CFU-GM) were found to have acquired the transferred sequence as determined by polymerase chain reaction analysis. In addition, in two experiments, 24-44% of the clonogenic progenitors derived from long-term myeloid cultures 9 weeks post-transduction were found to contain vector sequence. The latter cells are derived from so-called "long-term culture-initiating cells" (LTC-IC), which are primitive cells probably related to hematopoietic stem cells. Moreover, the transduced ADA enzyme was found to be expressed in both normal and ADA-deficient erythroid colonies, and in the nonadherent cells of long-term bone marrow culture for at least 2 weeks at levels that approximate the endogenous ADA levels of normal erythroid cells. These results indicate that the ADA coding sequence can efficiently be introduced by retroviral gene transfer into both committed and primitive human hematopoietic progenitor cells, and that this will result in adequate expression of the transduced enzyme in the progeny of committed hematopoietic progenitors.

The aphasic isolate. A clinical-CT scan study of a particularly severe subgroup of global aphasics

This paper outlines the clinical and CT scan features of a subtype of global aphasia, characterized by an extreme loss of communicative abilities, verbal as well as nonverbal. Three to four weeks after a left hemisphere stroke, 17 patients were completely unable to communicate with people addressing them. Though there were differences in their willingness to interact with the environment, they were characterized by complete loss of speech output and by inaccessibility to any kind of message, whether given verbally or through gestures. Patients who survived were reassessed 6 and 12 mos later and half of them were still found in a state of complete communicative isolation. The remainder had somewhat improved, but remained globally aphasic. The attempt to find a CT scan basis for this picture was disappointing. Only 35% of patients had a lesional pattern in agreement with the traditional view that ascribes global aphasia to the involvement of Broca's and Wernicke's areas. The location of lesion in the other cases spanned from anterior cortical damage, to posterior cortical damage, to deep nuclei damage and none of the lesions that have been proposed to account for subcortical global aphasia was consistently observed.

[Kinematic study of the temporal coupling between the components of transport and manipulation during reaching and grasping movements]

In this study the temporal coupling between transport and manipulation components of prehension movements was tested. For this purpose two experiments were carried out. In Experiment 1 six normal subjects were required to reach and grasp one of three spheres located at three different distances (Blocked trials). In Experiment 2 a visual perturbation paradigm was used in which the location of the object to be reached and grasped could change at onset of arm movement (Perturbed trials). The results of this study exclude a temporal coupling between events of transport and manipulation components. On the contrary they suggest that manipulation component organizes its time course having information about the time required to reach the object.