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Biomedical subjects

M Rodriguez

Publications and source records attributed to M Rodriguez.

At least 361 records · Page 20Linked to original sources
PubMed1994

Analysis of sites of foot and mouth disease virus persistence in carrier cattle via the polymerase chain reaction.

This study was undertaken in order to explore possible sites of foot-and-mouth disease virus (FMDV) persistence during the carrier state. Tissue samples taken from experimentally infected animals at different times post-infection (p.i.) were examined by conventional viral isolation and the polymerase chain reaction (PCR) technique. The analysis of samples from several organs taken from 17 bovines between 3 and 270 days p.i. allowed the following conclusions: 1) Virus present in oesophageal-pharyngeal fluids (OPF) during the carrier state originates in the pharynx as shown by the detection of antisense FMDV RNA by PCR, 2) PCR is more sensitive than standard virus isolation techniques and may be used for the rapid detection of FMDV in specimens obtained during the acute stage of FMD and for identification of persistently infected cattle.

Animals↗
PubMed1994

Motor and somatosensory evoked potentials in mice infected with Theiler's murine encephalomyelitis virus.

We used an in vivo technique to record spinal motor and somatosensory evoked potentials in SJL/J and B10 mice chronically (4-10 months) infected with Daniel's strain of Theiler's murine encephalomyelitis virus (TMEV). SJL/J mice demonstrated primary spinal cord demyelination with chronic TMEV infection, whereas B10 mice were resistant to TMEV induced demyelination. Analysis based on the velocity of the initial peak of evoked responses demonstrated significantly slower conduction velocities in infected SJL/J mice as compared to age-matched uninfected SJL/J controls (p < 0.01) and infected B10 mice (p < 0.01). We noted no significant differences in conduction velocities of spinal evoked potentials recorded between uninfected SJL/J mice, uninfected B10 mice and infected B10 mice. Chronic infection with TMEV in susceptible SJL/J mice is associated with slowed conduction of spinal motor and somatosensory evoked potentials. This sensitive electrophysiologic assay will provide an in vivo method to test therapeutic regimens to inhibit demyelination or promote remyelination.

Animals↗
PubMed1994

Maternal ingestion of tyrosine during rat pregnancy modifies the offspring behavioral lateralization.

It was previously reported that oral administration of tyrosine (500 mg/kg) to pregnant rats increases tyrosine and monoamines level in the fetal brain and modifies locomotion during postnatal life. In the present study, it was found that this treatment alters behavioral lateralization in the offspring. Neonatal rats whose mothers received tyrosine during the second half of gestation showed a low level of absolute and population laterality in both tail and head movements. The alteration of behavioral lateralization was also found during postnatal development and during adulthood. The T-maze behavioral ontogeny was different for tyrosine-mother and sham-treated or untreated mother rats. During adulthood, the T-max lateralization after stress sessions (a procedure that decreases alternation behavior and facilitates the quantification of behavioral lateralization) was also different in control and tyrosine-mother groups. Neonatal and adult rats showed an increase in right-side movements probability. These data provide evidence that maternal ingestion of a catecholamine precursor during gestation may induce a long-lasting modification of the behavioral lateralization of the offspring.

Administration, Oral↗
PubMed1994

Permanent dopaminergic alterations in the n. accumbens after prenatal stress.

It has been suggested that stress during the initial stages of human life may serve as a predisposing factor to mental illness. Recently, we reported that in pregnant rats, stress induces an increase of behavioral depression in the female offsprings when adult. This article describes the effect of prenatal stress on central dopaminergic transmission during adulthood. The offspring of stressed mothers showed an increase of behavioral depression in the Porsolt test and a reduction of DOPAC, HVA, and DOPAC/DA index in the n. accumbens. The effect on the right accumbens was more marked than on the left. A great body of information exists to suggest that depression is related to a decrease of dopaminergic neurotransmission, and the present data provide new evidence in support of the hypothesis that maternal stress during gestation increases the risk of depression in the offspring. We are also reporting a hitherto uncommented relationship between behavioral depression in the Porsolt test and the decrease of dopamine transmission in the n. accumbens.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1994

Ontogenic development of brain asymmetry in dopaminergic neurons.

In the present study the right-left brain asymmetry of central dopamine (DA) systems during postnatal brain development is evaluated. DA and dihydroxyphenylacetic acid (DOPAC) levels increased from neonatal to adult life in both the forebrain and mesencephalon. This increase was not similar in the right and left brain sides. From neonatal life to adulthood a fall was observed in (a) DA percentage in the DA high-brain side in the mesencephalon and (b) DOPAC percentage in the DOPAC high-brain side in both the forebrain and mesencephalon. The percentage of lateralized rats (more than 65% of DA or DOPAC levels in either brain side) also decreased during ontogeny. Thus, biochemical lateralization decreases during ontogeny. The right-left brain correlation for DA level and DA turnover was used to evaluate the inter-hemispheric regulation of dopaminergic systems. The correlation coefficient was near to 0 during postnatal life and around -0.8 during adulthood in both forebrain and mesencephalon. Taken together, these data suggest that the ontogenic decrease of in brain asymmetry for DA or DOPAC levels is related to the postnatal development of an inter-hemispheric regulatory system that control dopaminergic neurons activity.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1994

Immune promotion of central nervous system remyelination.

Remyelination by oligodendrocytes is the normal response to injury of the central nervous system following experimental demyelination by toxins and viruses in rodents. By contrast, in immune-mediated myelin disorders such as human MS, Theiler's virus-induced demyelination or EAE, remyelination is incomplete. We have considered two hypotheses to explain why myelin repair is incomplete in these disorders. Hypothesis I is that myelin repair is the normal consequence of primary myelin injury but there are immune factors which prevent its full expression. To test hypothesis I, we depleted T cells in Theiler's virus infected mice with cyclophosphamide or with monoclonal antibodies to CD4, CD8, or immune response gene products (Ia). Enhanced remyelination and proliferation of glial cells was observed in mice depleted of CD4+ or CD8+ T cells. Hypothesis II is that there are immune factors within some demyelinated lesions which, when present, promote new myelin synthesis. We envision these factors to be present in those lesions showing remyelination but absent in those lesions that remain demyelinated. To test hypothesis II, we generated polyclonal immunoglobulins directed against normal CNS antigens. Transfer of immunoglobulins from mice immunized repeatedly with spinal cord homogenate resulted in 4-5-fold enhancement of remyelination in Theiler's virus infected mice. We have also generated a series of monoclonal antibodies directed against normal autoantigens which also promote CNS remyelination. These experiments support the concept that full CNS remyelination is possible in human demyelinating diseases such as MS. Manipulation of the immune response either by inhibiting the function of T cells or by treatment with immunoglobulins (possibly normal autoantibodies) appears to promote remyelination. These experiments provide hope for patients with fixed neurological deficits for whom there are currently no available therapies.

Adjuvants, Immunologic↗
PubMed1994

Effects of estradiol on radial arm maze performance of young and aged rats.

Gonadectomized male and female Sprague-Dawley rats, given estradiol (E2) via sc Silastic capsules that generated proestrus levels of hormones, were tested for spatial memory performance on an 8-arm radial maze. Performance of males, with or without E2, exceeded that of females, with or without E2, for choice accuracy parameters over 20 trials. In addition, males reached criterion earlier than females (6 vs 11 trials). There were no significant effects of E2 on performance of either sex. When a 1-h delay was instituted between the 4th and 5th choices, the performance of males remained better than that of the females, and E2 administration was associated with a small, but significant, improvement in performance of the males but not the females. E2 administration to 25-month-old males also did not affect performance in regular trials, but performance was enhanced in trials with delays of 1-3 h after the 4th choice. These results show that estradiol can influence spatial memory performance and suggest that E2 may be beneficial for age and/or disease-related memory impairments.

Aging↗
PubMed1994

[Long-term outcome of a silastic semilunar bone prosthesis].

Eight silastic implants of the lunate bone were inserted between 1980 and 1984 on 8 patients. Seven patients were seen, at a ten year follow-up visit and were satisfied with the results. However, STT osteoarthritis secondary to the carpal collapse had to be stabilized by a triscaph arthrodesis. The clinical course showed a clear improvement of force and mobility in a first phase, followed by progressive deterioration ending in a return to preoperative values. Multiple intracarpal cysts were found radiologically in all wrists as well as in the distal radius in two cases and in the metacarpal bones in 3 cases. The height of the prosthesis was decreased by about 36%. Carpal collapse and ulnar translation showed a statistically significant progression. According to these findings, silastic prostheses should no longer be recommended.

Adolescent↗
PubMed1994

Factors in the development of secondary hyperparathyroidism during graded renal failure in the rat.

Secondary hyperparathyroidism (2 degree HPT) develops as a result of renal failure. Hypocalcemia, phosphorus retention, calcitriol deficiency and skeletal resistance to the calcemic action of parathyroid hormone (PTH) are closely interrelated pathogenic factors important for the development of 2 degrees HPT in renal failure. Since previous studies have mainly focused on advanced renal failure, only limited data are available in early renal failure. The goal of the present study was to evaluate how alterations in the dietary calcium and phosphorus composition affect the factors known to contribute to the genesis of 2 degrees HPT in early and more advanced renal failure. To achieve this goal, graded differences in renal function were surgically induced in 453 rats while the dietary content of calcium and phosphorus was varied. Three different diets were used: (1) a high phosphorus diet (HPD), to induce phosphorus retention and stimulate 2 degrees HPT; (2) a high calcium diet (HCaD), to inhibit calcitriol synthesis; and (3) a moderate calcium-moderate phosphorus diet (MCaPD), to separate the effects of high dietary phosphorus and calcium. Based on the serum creatinine (SCr) concentration rats were assigned to one of four different groups: (1) normal renal function (SCr < or = 0.3 mg/dl); (2) mild renal failure (SCr 0.4 to 0.6 mg/dl); (3) moderate renal failure (SCr 0.7 to 0.8 mg/dl); or (4) advanced renal failure (SCr > or = 0.9 mg/dl). As the severity of renal failure increased, progressive 2 degrees HPT developed in each of the dietary groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

The calcemic response to PTH in the rat: effect of elevated PTH levels and uremia.

Secondary hyperparathyroidism (2 degrees HPT) is a consistent finding in renal failure. A decreased calcemic response (CR) to parathyroid hormone (PTH) contributes to the development of 2 degrees HPT. Since parathyroidectomy (PTX) corrects the decreased CR to PTH in azotemic animals, down-regulation of PTH receptors induced by an elevation of PTH has been advanced as an important factor in the development of 2 degrees HPT. The goal of the study was to determine in azotemic rats whether a progressive reduction of PTH improves the CR to PTH and whether the maintenance of normal PTH levels corrects the CR to PTH. Seven groups of pair-fed rats were studied. Three groups of rats had normal renal function (NRF groups) and received either a high phosphorus (HPD-NRF), a moderate phosphorus (MPD-NRF), or a low phosphorus (LPD-NRF) diet. Three azotemic (NX) groups received similar diets (HPD-NX, MPD-NX and LPD-NX groups) in order to vary the magnitude of 2 degrees HPT. A PTX was performed in a fourth azotemic group (PTX-NX) to induce the complete absence of PTH. After 14 to 16 days on the maintenance diets, the CR to PTH was determined with a 48 hour infusion of 1-34 rat PTH.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Severe life-threatening cholera associated with blood group O in Peru: implications for the Latin American epidemic.

A household survey in 1991, at the onset of the Latin American cholera epidemic, investigated high attack rates in Trujillo, Peru, and determined the association between blood group O and severe cholera. Of 463 persons in 69 households, 173 (37%) reported diarrhea, 21% required rehydration therapy, and 4% were hospitalized; these treatment requirements greatly exceeded estimates based on other populations. Elevated vibriocidal or antitoxic antibody titers were present in 52% of 321 from whom serum was obtained; 73% were blood group O. Blood group O was strongly associated with severe cholera: Infected persons had more diarrheal stools per day than persons of other blood groups, were more likely to report vomiting and muscle cramps, and were almost eight times more likely to require hospital treatment. Since prevalence of blood group O in Latin America may be the world's highest, estimates of treatment requirements should be increased to prevent unnecessary deaths.

ABO Blood-Group System↗
PubMed1994

Adynamic bone disease with negative aluminium staining in predialysis patients: prevalence and evolution after maintenance dialysis.

Aplastic bone disease (ABD) is a common form of renal osteodystrophy and is characterized by a defect in bone matrix formation and mineralization without an increase in osteoid thickness. The prevalence and pathogenesis of ABD in predialysis patients is largely unknown. We prospectively studied 92 unselected predialysis patients with a creatinine clearance < 10 ml/min/1.73 m2 and a mean age of 45 +/- 2 years (61 M, 31 F). None of the study patients had received any form of vitamin D therapy, and CaCO3 was the primary phosphate binder. Aplastic bone disease was observed in 30 (32%) patients. Stainable bone aluminium surface was < 3% in all ABD patients. Patients with ABD were older (52 +/- 3 versus 42 +/- 2 years; P < 0.01) and had reduced serum intact PTH compared to non-ABD patients (199 +/- 25 versus 561 +/- 87 pg/ml; P < 0.001). Patients with diabetes mellitus showed lower PTH values (179 +/- 31 versus 432 +/- 62 pg/ml; P < 0.001) and a lower incidence of advanced hyperparathyroidism bone lesions (16% versus 46%; P < 0.05) than non-diabetic patients. However, diabetes was not clearly associated with low bone turnover disease (56% in diabetics versus 41% in non-diabetics; P = 0.1). A second bone biopsy was obtained in eleven ABD patients after a period of 16.6 +/- 2.2 months on maintenance dialysis with a dialysate calcium of 7 mg/dl. Bone histology was unchanged in 10 patients, and one evolved to mild hyperparathyroidism. Trabecular bone volume did not change (22.7 +/- 1.7 versus 20.7 +/- 1.7%), and the stainable bone aluminium surface remained < 3%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

The role of steroids in the management of metastatic carcinoma to the brain. A pilot prospective trial.

This prospective study attempted to evaluate the indications for glucocorticoids which are commonly given to patients with brain metastases. Twelve patients with histologically confirmed malignancies and radiographically documented brain metastases were enrolled. Patients were scored for general performance status and neurologic function class. All subjects were given high-dose dexamethasone (HDD) for 48 hours and then randomized to receive either intermediate-dose dexamethasone (IDD) or no steroids with cranial radiotherapy. Of these 12 study patients, 3 achieved a complete response, 1 partial response, and 8 nonresponses to HDD. Seven patients had IDD, while five received no IDD. Although a small sample size prevented any statistical analysis, this study does suggest that the place for using glucocorticoids in treating patients with metastatic carcinoma to the brain remains uncertain and should be evaluated in a cooperative prospective trial.

Adult↗
PubMed1994

Proteolipid protein gene expression in demyelination and remyelination of the central nervous system: a model for multiple sclerosis.

We asked whether nonlethal injury to the oligodendrocyte as manifested by altered myelin gene expression is an early event in the pathogenesis of demyelinating disease and subsequent remyelination. Using simultaneous in situ hybridization and immunocytochemistry, we studied expression of proteolipid protein (PLP) antigen and mRNA in spinal cords of normal adult mice and of mice infected with Theiler's virus which provides an excellent model for multiple sclerosis. Downregulation of PLP mRNA was observed within 3 days and persisted for as long as 367 days following intracerebral virus infection of SJL/J mice which are susceptible to chronic demyelination. Downregulation of myelin gene products preceded the development of prominent inflammation and demyelination observed following virus infection. In contrast, no change from control uninfected mice was observed in the expression of PLP mRNA following infection of C57BL/10SNJ mice which are resistant to demyelination. Treatment of chronically infected susceptible SJL/J mice with a regimen which promotes CNS-type (oligodendroglial) remyelination resulted in a 3- to 4-fold increase in PLP mRNA expression in oligodendrocytes. Actin mRNA expression in PLP antigen-positive cells was unchanged following TMEV-induced demyelination or remyelination indicating up- or downregulation of myelin gene products as compared to constitutively expressed actin gene. These experiments support the hypothesis that early regulation of myelin gene expression may be an important determinant in demyelination and in remyelination following nonlethal injury to oligodendrocytes.

Animals↗
PubMed1994

Heterosexual transmission of hepatitis C virus and the possible role of coexistent human immunodeficiency virus infection in the index case. A multicentre study of 423 pairings.

OBJECTIVES: To define the role that sexual transmission plays in the spread of hepatitis C virus (HCV) infection, and to examine the influence of coexistent human immunodeficiency virus (HIV) infection on this mode of transmission. DESIGN: A multicentre, seroprevalence study of anti-HCV performed in the stable heterosexual partners (SHP) of index cases reactive for anti-HCV. SETTING: Department of Internal Medicine and Section of Gastroenterology of three University Hospitals, Spain. SUBJECTS: A total of 423 stable heterosexual partners of index cases reactive for anti-HCV. This included a group of 142 intravenous drug users (IVDU), 120 of whom were coinfected with HIV. Additionally, 2886 first-time voluntary blood donors selected at random were included to compare the prevalence of anti-HCV. MAIN OUTCOME MEASURES: Serum samples were screened for anti-HCV by a commercially available, second-generation enzyme-linked immunoassay. Tests repeatedly reactive for anti-HCV were analysed by a four-antigen, recombinant immunoblot assay. Anti-HIV was tested by enzyme immunoassay and Western blot was used for confirmation of positive cases. RESULTS: The prevalence of anti-HCV, was 7.1% in SHP and 1.2% in random donors (P < 0.001). This prevalence was higher in SHP of index cases coinfected with HIV in comparison with that shown in the SHP of index cases only reactive for the anti-HCV (9.1 vs. 6.3%; P = 0.2), particularly when a younger and more homogeneous group such as the SHP of IVDU index cases was considered alone (9.2 vs. 0%; P = 0.1). However, the SHP of IVDU index cases coinfected with HIV were almost three times more likely to be infected with HIV than HCV (24.2 vs. 9.2%). CONCLUSIONS: These data suggest that HCV infection may be sexually transmitted but with low efficiency, and this could be increased in the presence of coexistent HIV infection in the index case.

Adolescent↗
PubMed1994

Detection of Bm86 antigen in different strains of Boophilus microplus and effectiveness of immunization with recombinant Bm86.

The control of tick populations by using conventional strategies poses several problems, including the appearance of organophosphate resistant strains, among others. The possibility of using alternative strategies such as vaccination with tick antigens has been suggested by several authors. One particular antigen (Bm86) has been described and shown to be able to induce a protective immunity against the cattle tick Boophilus microplus. In this paper we demonstrate by means of immunohistochemical staining that this antigen is conserved among several strains of this species. These results correlate with those showing that animals vaccinated with a preparation of recombinant Bm86 were protected against challenge with the four different strains tested, including one resistant to organophosphates. These results favour the immunization with recombinant Bm86 for the control of the cattle tick B. microplus.

Animals↗
PubMed1994

Defective G2 repair in Down syndrome: effect of caffeine, adenosine and niacinamide in control and X-ray irradiated lymphocytes.

Lymphocytes from both Down syndrome (DS) patients and age-matched control donors have been investigated to identify a possible disturbance in chromosomal G2 repair. Analyses of caffeine treatments during G2 have shown that the frequency of chromosomal aberrations is higher in DS lymphocytes than in normal lymphocytes. Likewise, G2 duration is longer in DS cells than in normal cells. In both control and DS lymphocytes, caffeine treatments increase the frequencies of chromatid breakages and decrease the average of G2 duration. The reversal of the caffeine potentiation effect by adenosine and niacinamide is higher in DS cells than in normal cells. Furthermore, ATP content per cell in DS lymphocytes is one third of that estimated in normal lymphocytes. The increase of ATP level produced by adenosine or niacinamide generally correlates with the reversal of the caffeine effect on chromosome aberrations. Under the experimental conditions tested, a good negative exponential correlation between ATP level and chromosome aberrations has been detected in both normal and DS lymphocytes which were or were not X-irradiated. Finally, we postulate a decrease in G2 repair capability of DS lymphocytes caused by a low availability of ATP and/or some other factor correlating with it.

Adenosine↗