Anti-Tr antibodies as markers of paraneoplastic cerebellar degeneration and Hodgkin's disease

BACKGROUND

Preliminary studies suggested that anti-Tr antibodies identify patients with paraneoplastic cerebellar degeneration (PCD) and Hodgkin disease (HD).

OBJECTIVE

To extend the clinical-immunologic analysis to 28 patients with anti-Tr antibodies.

METHODS

Anti-Tr antibodies were detected by immunohistochemistry. A competitive inhibition assay was used to ascertain if anti-Tr antibodies of different sera identify common epitopes. Anti-Tr immunoglobulin G (IgG) subclass distribution was determined by immunohistochemistry using monoclonal antibodies against human IgG isotypes. Tr immunoreactivity was analyzed in tumor sections using biotinylated anti-Tr IgG.

RESULTS

Median age of the 28 patients was 61 years (range 14 to 75 years) and 22 were male. A cerebellar syndrome was present in 27 patients and a possible limbic encephalitis in one. HD was diagnosed in 25 patients. No tumor was found in three patients; the autopsy of one of them disclosed severe loss of Purkinje cells without inflammatory infiltrates. Anti-Tr antibodies spontaneously disappeared in all patients without tumor and in 10/10 patients after successful HD treatment. Anti-Tr antibodies were absent in the serum but positive in the CSF of two patients. All positive anti-Tr sera inhibited the immunoreactivity of biotinylated anti-Tr IgG. The predominant isotypes of anti-Tr were IgG1 and IgG3. Only 1 out of the 15 HD samples studied presented anti-Tr positivity that was localized in some Reed-Sternberg cells.

CONCLUSIONS

This study confirms the strong association between anti-Tr antibodies and PCD associated with HD. Anti-Tr antibodies from different patients recognize similar epitopes. Unlike other antineuronal antibodies, anti-Tr antibodies can be detected in the CSF but not in the serum and may spontaneously disappear during the follow-up, and Tr immunoreactivity is usually lacking in the tumor.

Polymorphism in intron 2 of islet amyloid polypeptide gene is associated with lower low-density lipoprotein cholesterol in nondiabetic subjects and in type 2 diabetic patients

The aim of this study was to investigate the presence of mutations in the islet amyloid polypeptide (IAPP) gene in a Spanish population with type 2 diabetes and gestational diabetes mellitus (GDM). Using polymerase chain reaction single-stranded conformation polymorphism, we examined the coding region and the 5'-untranslated region (UTR) of the IAPP gene in 177 unrelated type 2 diabetic patients, 110 healthy control subjects, 38 women with GDM, and 38 gestational control subjects. Mutations were confirmed by DNA sequencing. A heterozygous C-to-A nucleotide substitution at +79 bp in intron 2 of the IAPP gene was detected. The frequencies of the +79-bp polymorphism (A allele) were 6.8% in type 2 diabetic patients, 7.7% in nondiabetic control subjects, 11.8% in women with GDM, and 9.2% in gestational control subjects. No AA genotypes were detected. Nondiabetic subjects and patients with type 2 diabetes bearing the CA genotype had lower low-density lipoprotein (LDL) cholesterol levels than subjects bearing wild genotype. Multivariate logistic regression analysis showed an independent association (p < 0.001; odds ratio: 0.33; 95% confidence interval: 0.17-0.63). We did not detect any sequence variant within exons 1 or 2. One diabetic patient was heterozygous for a silent mutation at codon 31 of exon 3 (Asn31 AAC --> AAT). Our findings indicate that the presence of the +79-bp polymorphism of the IAPP gene in nondiabetic subjects and in patients with type 2 diabetes is associated with lower levels of LDL cholesterol. Furthermore, abnormalities of the coding regions or the 5'-UTR of the IAPP gene are not associated with type 2 diabetes or GDM in the Spanish population.

[Intravenous multi vitamin formulation to use in pediatric total parenteral nutrition]

BACKGROUND

No intravenous multivitamin formulation is available at the Chilean market that fulfills the requirements of pediatric patients on total parenteral nutrition. Therefore, adult formulations must be used.

AIM

To prepare a parenteral aqueous multivitamin solution, to be used in pediatric patients.

MATERIAL AND METHODS

The solution was prepared, mixing vitamins according to their stability and compatibility, in a horizontal laminar flow hood. The quality control for this formulation at times zero and 30 days consisted of an organoleptic analysis, microbiologic and pyrogen controls and vitamin quantification. In addition, the effect of vitamin solution incorporation on the stability of total parenteral nutrition formulae was evaluated. The approximated production cost was calculated.

RESULTS

The ampoules did not show changes on the organoleptic characteristics. No bacterial contamination or pyrogens were detected. Total parenteral nutrition solutions were not modified after the incorporation of the vitamins. The vitamin solution was stable for one month at 4 degrees C.

CONCLUSIONS

The manufacture of this formulation results in significant savings, because it has a low manufacturing cost and fulfills pediatric requirements.

A graph layout algorithm for drawing metabolic pathways

MOTIVATION

A large amount of data on metabolic pathways is available in databases. The ability to visualise the complex data dynamically would be useful for building more powerful research tools to access the databases. Metabolic pathways are typically modelled as graphs in which nodes represent chemical compounds, and edges represent chemical reactions between compounds. Thus, the problem of visualising pathways can be formulated as a graph layout problem. Currently available visual interfaces to biochemical databases either use static images or cannot cope well with more complex, non-standard pathways.

RESULTS

This paper presents a new algorithm for drawing pathways which uses a combination of circular, hierarchic and force-directed graph layout algorithms to compute positions of the graph elements representing main compounds and reactions. The algorithm is particularly designed for cyclic or partially cyclic pathways or for combinations of complex pathways. It has been tested on five sample pathways with promising results.

[Analysis of mutations A3243G, C3256T and mitochondrial deletions in 41 diabetic patients]

BACKGROUND

Mutations or deletions of mitochondrial DNA (mtDNA) define a new diabetes subtype.

PATIENTS AND METHOD

The A3243G and C3256T mutations and mtDNA deletions were studied in 41 diabetic patients with maternally inherited diabetes mellitus or deafness.

RESULTS

The A3243G mutation was found in one out of forty-one diabetic patients (2.4%). Neither the C3256T mutation nor mtDNA deletions were detected.

CONCLUSIONS

The search of A3243G mutation has to be considered in a diabetic patient with deafness and/or maternal history of diabetes.

A quantitative study of fault tolerance, noise immunity, and generalization ability of MLPs

An analysis of the influence of weight and input perturbations in a multilayer perceptron (MLP) is made in this article. Quantitative measurements of fault tolerance, noise immunity, and generalization ability are provided. From the expressions obtained, it is possible to justify some previously reported conjectures and experimentally obtained results (e.g., the influence of weight magnitudes, the relation between training with noise and the generalization ability, the relation between fault tolerance and the generalization ability). The measurements introduced here are explicitly related to the mean squared error degradation in the presence of perturbations, thus constituting a selection criterion between different alternatives of weight configurations. Moreover, they allow us to predict the degradation of the learning performance of an MLP when its weights or inputs are deviated from their nominal values and thus, the behavior of a physical implementation can be evaluated before the weights are mapped on it according to its accuracy.

Short-term prediction of chaotic time series by using RBF network with regression weights

We propose a framework for constructing and training a radial basis function (RBF) neural network. The structure of the gaussian functions is modified using a pseudo-gaussian function (PG) in which two scaling parameters sigma are introduced, which eliminates the symmetry restriction and provides the neurons in the hidden layer with greater flexibility with respect to function approximation. We propose a modified PG-BF (pseudo-gaussian basis function) network in which the regression weights are used to replace the constant weights in the output layer. For this purpose, a sequential learning algorithm is presented to adapt the structure of the network, in which it is possible to create a new hidden unit and also to detect and remove inactive units. A salient feature of the network systems is that the method used for calculating the overall output is the weighted average of the output associated with each receptive field. The superior performance of the proposed PG-BF system over the standard RBF are illustrated using the problem of short-term prediction of chaotic time series.

Long-term clinical outcome of paraneoplastic cerebellar degeneration and anti-Yo antibodies

The outcome of 34 women with anti-Yo-associated paraneoplastic cerebellar degeneration was reviewed. Three patients had not developed cancer after more than 4 years of follow-up. The only independent predictor for survival was the type of associated tumor (risk ratio, 1.79; 95% CI, 1.02 to 3.12). Median survival was 100 months for patients with breast cancer and 22 for those with gynecologic cancer. Although paraneoplastic cerebellar degeneration leads to the diagnosis of cancer in 63% of the patients, cancer progression was the cause of death in 52%.

Etiological Characterization of 512 Severely Mentally Retarded Institutionalized Patients in Havana

OBJECTIVE

To investigate etiological factors in severe mental retardation (SMR).

METHODS

An etiological study is presented of 512 SMR patients in five specialized institutions in Havana.

RESULTS

Prenatal, perinatal and postnatal causes were apparent in 58.0, 24.8 and 11.1% of the patients, respectively; infantile psychosis was determined in only 0.4%. The remaining 5.6% were classified as having SMR of undeterminable origin, i.e. patients with apparently normal pre-, peri- and postnatal histories who had neither dysmorphism nor affected first-degree relatives, and had a normal karyotype and metabolic screen. Among prenatal causes, genetic factors were the most frequent (82.8%), while environmental factors were apparent in only 5.3% of these cases. Of the cases with prenatal genetic etiology, chromosomal aberrations were present in 86.5% (Down syndrome 96.2% and 3.7% other chromosomal aberrations), monogenic disorders in 11.3% [neurocutaneous diseases (32.1%) and fragile X syndrome (25%) were the most frequent], and multifactorial disorders in 2.0%. Thirty-five patients (11.7%) presented multiple congenital anomalies of 'prenatal unknown' causes. The latter group may include unidentifiable chromosomal aberrations, uniparental disomy, de novo mutations and multifactorial or teratogenic factors.

CONCLUSION

Accurate determination of the etiology of SMR is important not only for genetic counseling purposes, but also in identifying prenatal events which make infants more vulnerable to perinatal risk factors.

The search for natural bioactive compounds through a multidisciplinary approach in Bolivia. Part II. Antimalarial activity of some plants used by Mosetene indians

Forty-six different species collected in the Mosetene ethnia, dwelling in the Andean Piedmont of Bolivia, were screened for antimalarial properties. Thirty-three extracts were screened for antimalarial activity in vitro on Plasmodium falciparum chloroquine resistant strain (Indo), and forty-seven extracts were evaluated in vivo on the rodent malaria P. vinckei petteri 279BY. Only two plants are specifically used in combination by the Mosetene against malaria attack (Hymenachne donacifolia and Tesseria integrifolia), but they did not display any activity in vivo at 1000 mg/kg. The in vivo most active extracts were Swietenia macrophylla bark, Trema micrantha bark and Triplaris americana bark, not all of them were used for antimalarial purposes by the Mosetene. The following extracts were moderately active: Jacaratia digitata inner bark and Momordica charantia aerial part (both traditionally used as febrifuge), Kalanchoe pinnate aerial part (used in inflammatory processes), Lunania parviflora twigs and leaves, Phyllanthus acuminatus (used as piscicide), Tynanthus schumannianus fruit (used against diarrhoea), Triumfetta semitrilobata (used as febrifuge, to alleviate kidney and gynecological pain) and finally Solanum mammosum fruit (used against scabies). We present here the results of this screening, emphazing on the in vivo antimalarial activity of the selected plants. The antimalarial in vivo activity of the selected species, in relation with their traditional Mosetene use is then discussed.

A search for natural bioactive compounds in Bolivia through a multidisciplinary approach. Part I. Evaluation of the antimalarial activity of plants used by the Chacobo Indians

Thirty extracts of plants traditionally used by the Chacobos, a native community living in the Amazonian part of Bolivia, were screened in vitro and/or in vivo for antimalarial activity. Two of the four species designated as antimalarial, Geissospermum laeve and Maquira coriacea, displayed rather good activity, corroborating their traditional uses. However, they did show a rather high toxicity in vivo. Among twelve species used to cure symptoms relevant to malaria, five showed good activity: Apuleia leiocarpa, Bauhinia guianensis, Nectandra cuspidata, Sparattanthelium amazonum, Tanaecium jaroba. Two species, Qualea paraensis and Sclerolobium aff. guianense, used to treat scabies, showed interesting antimalarial activity in vivo; three other species (Iryanthera laevis, Prunus amplifolia, Pterocarpus aff. amazonum) used for various medicinal purposes, apparently not related with a Plasmodium infection, also showed antimalarial activity. Finally, one species (Derris amazonica) used as a piscicide displayed good in vitro activity, in the same way as one Annonaceae, Guatteria aff. schomburgkiana, used for construction purposes.

A new measurement of noise immunity and generalization ability for MLPs

This paper shows a quantitative relation between the regularization techniques, the generalization ability, and the sensitivity of the Multilayer Perceptron (MLP) to input noise. Although many studies about these topics have been presented, in most cases only one of the problems is addressed, and only experimentally obtained evidence is provided to illustrate some kind of correlation between generalization, noise immunity and the use of regularization techniques to obtain a set of weights after training that provides the corresponding MLP with generalization ability and noise immunity. Here, a new measurement of noise immunity for a MLP is presented. This measurement, which is termed Mean Squared Sensitivity (MSS), explicitly evaluates the Mean Squared Error (MSE) degradation of a MLP when it is perturbed by input noise, and can be computed from the statistical sensitivities (previously proposed) of the output neurons. The MSS provides an accurate evaluation of the MLP performance loss when its inputs are perturbed by noise and can also be considered a measurement of the smoothness of the error surface with respect to the inputs. Thus, as the MSS can be used to evaluate the noise immunity or the generalization ability, it gives a criterion to select among different weight configurations that present a similar MSE after training.

Stimulus correlation and adaptive motion detection using spiking neurons

Stimulus correlation and adaptive movement detection, among other tasks can be performed with VLSI general-purpose neurons that have controllable steady and transient responses. This paper presents experimental results of simple neural primitives based on the CMOS neuron approach described in [11]. Stimulus correlation experiments illustrate the well defined behavior of the CMOS approach. This basic primitive is used to implement motion detectors with adaptive capabilities that enable it to work efficiently in a wide velocity range.

Antimalarial activity and cytotoxicity of (-)-roemrefidine isolated from the stem bark of Sparattanthelium amazonum

(-)-Roemrefidine, an aporphine alkaloid isolated from Sparattanthelium amazonum Martius (Hernandiaceae) a vine from Bolivia, has been found to be active against both resistant and sensitive strains of Plasmodium falciparum in vitro and against P. berghei in mice. The compound demonstrated no cytotoxic activity against three cell lines (KB, HEp-2 and HeLa).

[An analysis of 6 Leber mutations in 31 individuals with optic atrophy. A study of its transmission in 5 families]

BACKGROUND

Leber's hereditary optic neuropathy (LHON) is a mitochondrial disorder that represents the most frequent cause of visual loss among otherwise healthy young men.

PATIENTS AND METHODS

We have screened for the most important LHON mutations (primary mutations) and several other previously described mutations (secondary mutations) in 31 Spanish patients suffering from optic atrophy. These individuals fulfilled the clinical criteria for LHON. We have compared the mutation frequencies obtained with those reported in several other countries. We have also followed the segregation of the disease and its associated LHON mutations in five families. The screening has been performed by PCR followed by restriction enzyme digestions and electrophoretic separation.

RESULTS

67.75% of the patients did not harbour any of the studied mutations, whereas 16.13% showed one mutation and the remaining 16.13% carried two Leber mutations in their mitochondrial DNA. The three primary mutations as well as G15257A were the changes most frequently detected (30% each of them). There were no significant differences among the compared populations in terms of frequencies of the primary mutations. In contrast, our patients showed a significantly higher rate of 15257 mutation.

CONCLUSIONS

The incidence of primary LHON mutations among the Spanish patients is not statistically different from those observed in other Caucasian populations. Transmission of the mutation to the progeny is not necessarily linked to the transmission of the disease. This fact complicates genetic counselling and makes prenatal diagnosis almost impossible for this disease.