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Biomedical subjects

J Perez

Publications and source records attributed to J Perez.

At least 37 records · Page 2Linked to original sources
PubMed2003

Distribution patterns of entomopathogenic nematodes applied through drip irrigation systems.

The distribution of entomopathogenic nematodes applied by drip irrigation was evaluated by injecting small volumes of Steinernema carpocapsae (Weiser) All strain, Steinernema feltiae (Filipjev) SN strain, Steinernema glaseri Steiner, and Heterorhabditis bacteriophora HP 88 strain Poinar suspensions into drip irrigation lines. Additionally, Steinernema riobrave Cabanillas, Poinar, & Raulston, and S. carpocapsae were injected in a 10-liter volume of water with an injection pump. Overall, the nematodes were evenly distributed along the drip lines. The total number of nematodes recovered from drip emitters was variable ranging from 42 to 92%. However, drip irrigation lines have potential to deliver entomopathogenic nematodes efficiently into pest habitats.

Agriculture↗
PubMed2002

BPTI liquid-liquid phase separation monitored by light and small angle X-ray scattering.

In the field of protein crystallization, a better knowledge of the nucleation process is essential to control the nucleation rate, the growth and therefore the size and the quality of crystals. With that aim, it becomes clear that the important stage is the determination of the protein phase diagram. We highlighted and investigated the bovine pancreatic trypsin inhibitor (BPTI) binary liquid-liquid phase separation in 350 mM KSCN solutions as a function of temperature. We measured the low concentration part of the binodal curve using light scattering and optical microscopy. We show, from small angle X-ray scattering experiments, that the high concentrated phase sediments in the bottom of the capillary and we analysed the low concentrated phase in terms of monomers/decamers equilibrium.

Animals↗
PubMed2002

Peroneal nerve palsy caused by thrombosis of crural veins.

Acute palsies of the peroneal nerve may have a variety of causes. In many patients, the cause remains undetermined. The authors report a patient with a thrombosis of a crural vein causing an acute peroneal nerve palsy. If the clinical history of patients with an acute peroneal nerve lesion is suggestive of venous thrombosis an appropriate diagnostic workup should be considered.

Acute Disease↗
PubMed2002

[Rhabdoid meningioma. A new malignant subtype].

Of the numerous morphological variants of meningiomas only few, and among these the rhabdoid meningioma, have prognostic importance. Rhabdoid meningiomas were described for the first time in 1998 as an unusual variant with increased proliferative activity. In 2000 they have been included in the revised WHO classification of tumours of the CNS as a subtype of meningiomas with increased risk of recurrence and more aggressive growth, corresponding to WHO grade III. We report the case of a rhabdoid meningioma in a 21-year-old woman presenting as a intracerebral tumour mimicking an oligodendroglioma. The tumour showed features of a meningioma and a rhabdoid morphology with angiomatous components and was considered to be a rhabdoid meningioma. After surgery a small residual tumour remained. The patient received postoperative radiotherapy resulting in regression of the residual tumour in control examinations after 4 and 8 months. Using the presented case we discuss the differential diagnosis and prognostic significance of recognition of a rhabdoid meningioma.

Brain Neoplasms↗
PubMed2002

Interspecific barriers between salmonids when hybridisation is due to sneak mating.

Male sneaking behaviour can lead to interspecific hybridisation if sneakers attempt to fertilise ova in heterospecific mating, contributing to break down of interspecific barriers. In south European rivers, sneaking Atlantic salmon males fertilise an important proportion of ova from adult females in heterospecific crosses, up to 65%. In a south French flow-controlled stream, we found that they were able to naturally fertilise brown trout ova in absence of brown trout males. Aggressiveness of brown trout males towards sneaking salmon males and low survival of hybrids issued from salmon sneakers are found to be interspecific barriers.

Animals↗
PubMed2002

cAMP signaling pathway in depressed patients with psychotic features.

Abnormalities in protein kinase A (PKA) and Rap1 have recently been reported in depressed patients. The aim of the present study was to investigate the levels of these proteins in platelets from untreated unipolar and bipolar depressed patients with psychotic features. The levels PKA and Rap1 were assessed by Western blot analysis and immunostaining in 37 drug-free patients and 29 healthy subjects. Both unipolar and bipolar patients with psychotic depression have significantly lower levels of platelet regulatory type I and higher levels of catalytic subunits of PKA than controls, whereas the levels of regulatory type II were higher only in psychotic unipolar patients. No significant differences were found in the immunolabeling of both Rap1 and actin among groups. These findings support the idea that besides nonpsychotic depression, abnormalities of PKA could be linked, albeit in a somewhat different way, with psychotic depression.

Adult↗
PubMed2002

Immunohistochemical characterization of tumor cells and inflammatory infiltrate associated with cutaneous melanocytic tumors of Duroc and Iberian swine.

The immunophenotype of tumor cells and inflammatory infiltrate associated with cutaneous melanocytic lesions (29 melanocytomas, two malignant melanomas, and 23 residual lesions) from 54 adult Iberian and Iberian x Duroc pigs were examined using a panel of nine antibodies. All neoplastic cells were vimentin+, cytokeratin-, and alpha-1-antitrypsin- and the majority were S100+, whereas all pigmented macrophages were vimentin+, cytokeratin-, and S100- and most expressed alpha-1-antitrypsin. Regressing tumors were characterized by zones with low density of neoplastic cells accompanied by heavy infiltration of CD3+ T lymphocytes, whereas zones with high density of neoplastic cells showed very low numbers of CD3+ T lymphocytes. The infiltrate of CD79a+ B cells and IgG, IgM, and IgA plasma cells was low. The majority of lymphocytes of the peri- and intratumoral infiltrate were major histocompatibility complex class II+, but neoplastic cells did not express class II antigen. The 17 residual lesions examined were composed of macrophages containing abundant melanin pigment and low to moderate numbers of CD3+ T lymphocytes. The results of the present study suggest that the local cellular immune response plays a crucial role in the host response that induces regression of cutaneous melanomas and melanocytomas of the Iberian and crossbred Iberian x Duroc pigs.

Animals↗
PubMed2001

Amyloid precursor protein in platelets: a peripheral marker for the diagnosis of sporadic AD.

BACKGROUND: An altered pattern of amyloid precursor protein (APP) forms consisting in a reduced ratio between the upper (130 kDa) and the lower (106 to 110 kDa) immunoreactivity bands has been described in platelets of patients with AD. OBJECTIVE: To evaluate the sensitivity and the specificity of platelet APP forms' ratio (APPr) as a marker for AD. METHODS: Eighty-five patients with probable AD and 95 control subjects (CON), including healthy individuals and neurologic patients, entered the study. Platelet APPr was evaluated by means of Western Blot analysis and immunostaining in the whole platelet homogenate, and calculated by the ratio between the optical density (OD) of the upper (130 kDa) and the lower (106 to 110 kDa) APP immunoreactive bands. RESULTS: Mean APPr levels were decreased in AD patients (mean OD +/- SD = 0.35 +/- 0.18) compared with the CON group (mean OD +/- SD = 0.92 +/- 0.38) (DF 1, 178, p < 0.0001). Accuracy levels measured by Receiver Operating Curve analysis showed that a cut-off level of 0.57 resulted in a sensitivity of 88.2% and a specificity of 89.4%, with an area under the curve of 0.945. APPr levels were significantly associated with disease severity (mild AD versus moderate AD: p < 0.0001; moderate AD versus severe AD: p < 0.05). CONCLUSION: Platelet APPr allowed to differentiate AD from normal aging and other dementing disorders with high sensitivity and specificity. These findings suggest that platelet APPr may be of help as an adjunctive diagnostic tool in clinical practice.

Aged↗
PubMed2001

Spherical plant viruses: interactions in solution, phase diagrams and crystallization of brome mosaic virus.

Brome mosaic virus (BMV) is a small icosahedral plant virus of mean diameter 268 A. Interactions between BMV particles in solution were studied by means of small-angle X-ray scattering in order to find crystallization conditions. The interactions between biomacromolecules as large as these viruses have not yet been systematically studied by this method. As it is known that usually proteins crystallize in, or close to, attractive regimes, the interactions between BMV particles in solution were studied as a function of pH, type of salt and size and concentration of polyethylene glycol. An unexpected result of these studies is that the precipitates obtained upon addition of PEG alone or PEG combined with salt were in fact made of microcrystals, which were all characterized by the same series of diffraction peaks, with positions close to those of a centered cubic space group. A phase diagram of the virus as a function of PEG concentration was established by means of microbatch experiments. From the precipitation zones, conditions for crystallization were tested from 5 to 40 mg ml(-1) virus with 3-10%(w/v) PEG 8000 or PEG 20,000. Small crystals were obtained in several conditions after a few days and continued growing for several weeks.

Bromovirus↗
PubMed2001

Thyroid hormone regulation of rhes, a novel Ras homolog gene expressed in the striatum.

Thyroid hormone action on brain development is essentially exerted through regulation of the expression rate of a number of genes some of which have been identified in the past 10 years. In the present work we describe the thyroid hormone regulation of a novel Ras homolog which we have named Rhes (Ras homolog enriched in striatum). The rhes cDNA was previously isolated in subtractive hybridization experiments aimed at identifying cDNA clones corresponding to genes expressed preferentially in the rat striatum. The sequence was found to encode a small GTP-binding protein of the Ras family with highest homology to the dexamethasone-inducible Dexras1. Here we show that rhes mRNA and protein in the striatum are strongly dependent on the thyroidal status. Developmentally, Rhes was regulated such that in normal rats there was an increased rhes mRNA content in the striatum after postnatal day 5 (P5). Rhes concentration in hypothyroid rats was similar to that of normal rats at P5, but the subsequent age-dependent increase was blunted. The administration of a single T3 dose to hypothyroid rats normalized rhes mRNA concentration in 8 h, whereas it took 24 h, or more, to normalize the expression of rc3, another T3-dependent brain gene, involved in PKC signaling. Double in situ hybridization using rhes and rc3 riboprobes showed that the bulk of rhes signal was located in cells expressing rc3. Given the relevance of small GTPases in signal transduction it is very likely that control of rhes, in addition to rc3, is of relevance to explain the actions of thyroid hormone in the striatum, a region of the brain especially vulnerable in neurological cretinism.

Amino Acid Sequence↗
PubMed2001

Searching for specific binding sites of the secretory glycoproteins of the subcommissural organ.

The molecular organization of Reissner's fiber (RF), the structure of its proteins, and the permanent turnover of these proteins are all facts supporting the possibility that RF may perform multiple functions. There is evidence that CSF-soluble RF-glycoproteins may occur under physiological conditions. The present investigation was designed to investigate the probable existence within the CNS of specific binding sites for RF-glycoproteins. Three experimental protocols were used: (1) immunocytochemistry of the CNS of bovine fetuses using anti-idiotypic antibodies, raised against monoclonal antibodies developed against bovine RF-glycoproteins; (2) in vivo binding of the RF glycoproteins, perfusing into the rat CSF 125I-labeled RF-glycoproteins, or grafting SCO into a lateral ventricle of the rat; (3) in vitro binding of unlabeled RF-glycoproteins to rat and bovine choroid plexuses maintained in culture. One of the anti-idiotypic antibody generated by a Mab raised against RF-glycoproteins binds to choroidal cells. Furthermore, binding of RF-glycoproteins to the rat choroid plexus was obtained when: (1) the choroid plexus was cultured in the presence of unlabeled RF-glycoproteins; (2) the concentration of soluble RF-glycoproteins in the CSF was increased by isografting SCOs into a lateral ventricle; (3) radiolabeled glycoproteins were perfused into the ventricular CSF. This evidence suggests that the apical plasma membrane of the ependymal cells of the choroid plexus has specific binding sites for RF-glycoproteins, of unknown functional significance. The radiolabeled RF-glycoproteins perfused into the rat CSF also bound to the paraventricular thalamic nucleus, the floor of the Sylvian aqueduct and of the rostral half of the fourth ventricle, and the meninges of the brain and spinal cord. The labeling of the paraventricular thalamic nucleus points to a functional relationship between this nucleus and the SCO. The possibility that the SCO may be a component of the circadian timing system is discussed.

Animals↗
PubMed2001

Distribution of aflatoxin M1 in cheese obtained from milk artificially contaminated.

Small-scale manufacture of cheese using artificially AFM1 contaminated milk as raw material to study the distribution of such toxin both in whey and in cheese, was carried out. Whole milk with undetectable levels of AFM1 was used. The toxin was added in concentration that varied from 1.7 to 2.0 microg/l of milk. After the home-made production of cheese, the concentration of AFM1 was determined both in whey and in cheese, using the enzymatic immunoassay technique. The greatest proportion, 60%, was detected in whey while 40% AFM1 remained in cheese.

Aflatoxin M1↗
PubMed2001

Continuous positive airway pressure and obstructive sleep apnea in an Hispanic population.

OBJECTIVES: We sought to explore the relationship between the diagnosis of hypertension and obstructive sleep apnea (OSA) in a Hispanic population, describe the effect of continuous positive airway pressure (CPAP) on blood pressure regulation, and assess the effect of CPAP on quality of life. DESIGN: A retrospective, recall interview study. PARTICIPANTS: Patients enrolled at the Home Oxygen Program of the San Juan V.A. Medical Center with the diagnosis of OSA and treatment with CPAP. MEASUREMENTS: The Calgary Sleep Apnea Quality of Life Index was administered to all patients after informed consent. Information regarding co-morbid conditions and fluctuations in blood pressure and anthropometric variables were obtained on a follow-up evaluation. RESULTS: After excluding for the use of antihypertensive medications, weight, and age, a 10% decrease in mean arterial pressure (MAP) from 100 mm Hg to 92 mm Hg was observed in an average of 40 months of therapy (p < 0.05). With the Calgary Quality of Life Index, 67% of the patients reported an extreme improvement in their quality of life. Compliance with CPAP therapy correlated with improved quality of life (r = 0.33, p < 0.015). CONCLUSIONS: In this pilot study, there appears to be a correlation between our intervention and decline of blood pressure, independent of body weight, age, or medication usage. CPAP treatment is an effective modality in improving symptoms and quality of life.

Adult↗
PubMed2001

Effect of reboxetine treatment on brain cAMP- and calcium/calmodulin-dependent protein kinases.

Previous studies showed that the type II Ca(2+)/calmodulin- and cAMP-dependent protein kinases (CaMKII and PKA) are affected by long-term antidepressant treatment in presynaptic and somatodendritic compartments, respectively. This study describes the long-term effects of the selective noradrenaline reuptake inhibitor reboxetine on PKA and CaMKII, in both the microtubule and subsynaptosomal fractions of rat brain. Unlike other antidepressants, chronic reboxetine induced in the cerebrocortical soluble and microtubule fractions a decrease in the [(32)P]cAMP binding to the type II PKA regulatory subunit. No change in the cAMP-dependent endogenous phosphorylation of the protein substrate, microtubule-associated protein 2 was observed. In the hippocampal subsynaptosomal fractions (synaptic vesicles and synaptosomal membranes) reboxetine induced a robust increase in the activity but not in the expression of CaMKII. An increase in the calcium/calmodulin-dependent phosphorylation of presynaptic substrates was also detected. These findings showed that reboxetine modulates post-receptor signal transduction systems in rat brain.

Adrenergic Uptake Inhibitors↗
PubMed2001

Serine/threonine kinases as molecular targets of antidepressants: implications for pharmacological treatment and pathophysiology of affective disorders.

It is currently a widely accepted opinion that adaptive, plastic changes in the molecular and cellular components of neuronal signaling systems correlate with the effects on mood and cognition observed after long-term treatment with antidepressant drugs. Protein phosphorylation represents a key step for most signaling systems, and it is involved in the regulation of virtually all cellular functions. Two serine/threonine kinases, Ca2+ /calmodulin-dependent protein kinase II and cyclic AMP-dependent protein kinase, have been shown to be activated in the brain following antidepressant treatment. The changes in kinase activity are mirrored by changes in the phosphorylation of selected protein substrates in subcellular compartments (presynaptic terminals and microtubules), which, in turn, may contribute to the modulation of synaptic transmission observed with antidepressants. The molecular consequences of protein kinase activation may account for some of the alterations in neural function induced by antidepressants, and may suggest novel possible strategies of pharmacological intervention.

Animals↗
PubMed2001

Valproate in very young children: an open case series with a brief follow-up.

We report nine cases of juvenile mania, of which six began in the preschool years. We provide validation by clinical description, family history of bipolar disorder, worsening on stimulants, and considerable mood stabilization with divalproex. This is a relatively new area of clinical observation, and systematic studies are needed to firmly establish this diagnostic category in very young children. Our case series enriches the existing scant literature and provide the rationale for the use of mood stabilizers rather than stimulants in this juvenile population. However, no controlled studies exist on the efficacy and safety of valproate in this age group; lithium that has received greater clinical attention, has not been subjected to controlled studies either. Our clinical observations with divalproex are preliminary but encouraging.

Affect↗
PubMed2001

The cAMP-dependent protein kinase substrate Rap1 in platelets from patients with obsessive compulsive disorder or schizophrenia.

Previous studies have reported that the cAMP-dependent protein kinase and one of its substrates, namely Rap1, are altered in patients with affective disorders. Abnormalities in the cAMP-dependent protein kinase have also been reported in platelets of patients with obsessive compulsive disorder and schizophrenia. However, it remains to be determined whether abnormalities in Rap1 are specifically related to affective disorders or may also be present in schizophrenia and obsessive compulsive disorder. Thus, we investigated Rap1 in platelets from 12 drug-free patients with obsessive compulsive disorder, ten drug-free patients with schizophrenia, and 20 healthy subjects. While no difference was observed in the levels of Rap1 between groups, the phosphorylation state of Rap1 was significantly lower in patients with obsessive compulsive disorder than in schizophrenic patients and controls. These data further support the idea that abnormalities of cAMP signalling pathway could be associated, albeit in a somewhat different way, with several psychiatric disorders.

Adult↗