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Biomedical subjects

V Rivera

Publications and source records attributed to V Rivera.

At least 19 recordsLinked to original sources
PubMed2004

Identifying and treating patients with suboptimal responses.

Multiple sclerosis (MS) is an immune-mediated neurologic disease in which acute inflammatory events early in the disease course contribute to subsequent neurologic disability. The early relapsing inflammatory phase is followed by a progressive degenerative phase in which the frequency of acute inflammatory attacks diminishes but progressive loss of neurologic function continues. Current immune therapies are most effective in suppressing the acute inflammatory events that characterize the earlier stages of disease. Optimal suppression of these inflammatory events is likely to have the best potential for delaying or preventing loss of axons and decline in neurologic function. In view of these considerations, and because MS is a heterogeneous disease and response to disease-modifying agents (DMA) varies across individuals, it is important to identify suboptimal responders as early as possible to allow therapeutic modification while the opportunity to avert future loss of function remains. At present, no criteria for identifying suboptimal responders have been validated. In January 2004, a group of neurologists from 16 MS centers in the United States met to develop a consensus on criteria for defining suboptimal response for use in compelling clinical situations and to prompt clinical studies to validate the efficacy of these criteria. Consensus criteria included relapse rates of either 1/year or unchanged from pretreatment rates, incomplete recovery from multiple attacks, evolution of polyregional neurologic involvement, recurrent brainstem or spinal cord lesions, and cumulative loss of neurologic function sufficient to disrupt daily activities. The panel then considered the use of mitoxantrone for patients with worsening MS and a suboptimal response to DMA therapy.

Clinical Trials as Topic↗
PubMed2002

Immunochemical characterisation of species-specific antigens in bovine crude heparin.

In order to develop immunoassays for the control of the species origin of crude heparins, polyclonal antisera were produced in rabbits against samples obtained from the last purification steps of bovine intestinal crude heparin. The reactivity of the antisera was analysed by agar gel double immunodiffusion, immunoelectrophoresis, crossed and line immunoelectrophoresis. Up to 13 antigenic components were detected in the effluents of the ion-exchange chromatographic step, and three in the final crude heparin. The major and most anodic antigen (Ag1) was recovered in bovine crude heparin purified by the two different industrial processes. This bovine specific antigen was found in high concentrations in lung, liver, small intestine, spleen and kidney. It displayed an apparent molecular weight of 45 kDa by size-exclusion chromatography. Though the identification of Ag1 is not yet fully elucidated, a single radial immunodiffusion assay has been developed for the quantification of this antigen, allowing the detection of 6 p 1000 bovine crude heparin in porcine heparin (50 mg/ml) after 2 h diffusion.

Animals↗
PubMed2002

Immunochemical control of the species origin of porcine crude heparin and detection of ovine and caprine materials.

As a consequence of the outbreak of bovine spongiform encephalopathy (BSE), ruminants materials have been generally banned from the production of heparin. Immunochemical methods have been recently developed for the control of the raw materials used by manufacturers of materials such as porcine mucosa and for the detection of bovine crude heparins. To certify the porcine origin of crude porcine heparins and to exclude ovine or caprine materials, new ELISAs were developed. Rabbit antisera were produced against species-specific antigenic contaminants present in crude heparins or in eluted materials (EM) from the chromatographic step of the purification process. When analysed by line immunoelectrophoresis, these antisera revealed five to eleven antigenic contaminants in the EMs, the major one being the most anodic and predominant antigen in crude heparins. Using the best antisera, competitive indirect ELISAs were optimised. They allowed the detection of porcine, ovine and caprine crude heparins down to a dilution of 0.6 to 1.5 parts per 1000, with CVs ranging from 3 to 12%. These ELISAs complete the set of immunological techniques which can be routinely used by heparin manufacturers to secure their supply chain.

Animals↗
PubMed2001

A sensitive ELISA for the detection of bovine crude heparin in porcine heparin.

Heparin is an effective anticoagulant drug which has been purified for decades from bovine or porcine tissues. However, with the emergence of BSE, heparin purification is today restricted to porcine intestinal mucosa. To control the origin of crude heparins, polyclonal antibodies were raised against bovine contaminants. These antibodies were used to develop one sandwich and two competitive indirect ELISAs. Optimal results were obtained with competitive indirect ELISA, using bovine crude heparin for the coating and anti-bovine crude heparin as a detector antibody. The detection limit of the assay was 1 ppm of bovine crude heparin in a porcine heparin. Taking into account the variability of the background obtained for 10 crude and 9 pure porcine heparins from known origin, the detection level was 5 ppm. Ovine and caprine crude heparins cross-reacted slightly (6-17 ppm).

Animals↗
PubMed2001

IgA and IgM anti-Naegleria fowleri antibodies in human serum and saliva.

Antibodies from IgA and IgM classes that recognize Naegleria fowleri (Nf) proteins were detected by the ELISA assay in serum and saliva from three groups of people: (i) subjects with upper respiratory tract infections (URTI) living in the parasite-endemic area, (ii) healthy persons from the same area, and (iii) healthy persons from a parasite-nonendemic area. In serum and in saliva the titers of IgA antibodies to Naegleria fowleri in the group of patients with URTI was significantly higher than that of the healthy group in the parasite-endemic area; also the titers of IgM antibodies in serum were significantly higher in patients. On the contrary, in saliva the antibodies were higher in healthy people from the parasite-endemic area. In all cases the subjects from the parasite-nonendemic area had lower antibody titers in serum and saliva.

Adult↗
PubMed2000

Odontogenic keratocyst: the northwestern USA experience.

Odontogenic keratocyst (OKC) is a cyst of tooth origin with an aggressive clinical behavior including a high recurrence rate. OKC demographics in the northwestern United States are presented and compared to those reported elsewhere. A total of 430 cases were obtained from 393 patients of the northwest region over a period of 15 years. Data evaluated included: site, gender, age, race, and association with bifid-rib basal cell nevus syndrome (Gorlin syndrome). Site distribution of the northwest group was similar to that of international groups. For the northwest group, the most common lesion location was the body of the mandible. Gender distribution in the northwest group appeared similar to other reports made in Denmark, England, Japan, and other regions in the United States. However, when gender distribution was compared by decade of life, the northwest group had the largest cluster of males in the fourth decade and of females in the second decade. The greatest frequency in both genders occurred in the third decade. There were 18 of 258 (6.9%) male patients with OKC under age 10 in the northwest group and nearly 80% of the patients were Caucasian. The race factor is rarely described in other reports. Gorlin's syndrome was present in 5% of the patients, with a higher distribution in the first and second decades. In conclusion, this is the first report of OKC cases from the Pacific Northwest region of the United States of America.

Adolescent↗
PubMed1998

The correlation of urodynamic findings with cranial magnetic resonance imaging findings in multiple sclerosis.

PURPOSE: To our knowledge there are no studies of the correlation between urinary complaints or urodynamic findings in multiple sclerosis and magnetic resonance imaging (MRI) findings. We investigated the correlation of urodynamic results in multiple sclerosis patients with voiding complaints to the cranial MRI findings. We also sought to correlate urodynamic results in these patients with International Prostate Symptom Scores (IPSS). MATERIALS AND METHODS: We retrospectively reviewed urodynamic results and cranial MRI findings in 90 multiple sclerosis patients (64 women, 26 men, mean age 44.5 years) with voiding complaints. The most recent urodynamic study and cranial MRI for each patient were reviewed. The interval between the 2 studies and MRI was no more than 6 months. Detrusor contractions were categorized as areflexic, hyporeflexic, hyperreflexic or hyperreflexic with impaired contractility. The presence of impaired compliance or detrusor-external sphincter dyssynergia was recorded. The cranial MRI findings were categorized on the basis of the presence of atrophy or enhancing lesions, total number of lesions and size of largest lesion. The urodynamic and MRI findings were correlated. Of the patients 40 who had urodynamic studies done within the last 6 months completed the IPSS, and severity of cranial MRI findings in these patients was correlated with the IPSS results. In addition, the presence of irritative findings of detrusor hyperreflexia or detrusor hyperreflexia with impaired contractility was correlated with the irritative score (sum of questions 1, 2, 4, 7), and the presence of detrusor-external sphincter dyssynergia was correlated with the obstructive score (sum of questions 3, 5, 6). RESULTS: There was no correlation between urodynamic category, presence of impaired compliance or presence of detrusor-external sphincter dyssynergia and any of the MRI findings of atrophy or enhancing lesions, total number of lesions or size of the largest lesions. In the patients who completed the IPSS there was no correlation between total number of lesions and IPSS score. There was no correlation between the presence of detrusor-external sphincter dyssynergia and obstructive score on the IPSS or between the presence of detrusor hyperreflexia and irritative score. CONCLUSIONS: Although patients with multiple sclerosis often are followed closely with urodynamic studies and cranial MRI, there appears to be no correlation between these 2 studies. Symptom scores also do not appear to correlate with urodynamic findings. Therefore, urodynamic studies appear to be warranted and irreplaceable in the evaluation of voiding dysfunction in multiple sclerosis patients.

Adolescent↗
PubMed1995

Dichotic listening, event-related potentials, and interhemispheric transfer in the elderly.

OBJECTIVE: To determine the basis for the large, age-related asymmetries in dichotic listening performance scores reported by Jerger et al. (1994). DESIGN: Behavioral and electrophysiologic responses to dichotic listening tasks in both verbal and nonverbal paradigms were obtain in four groups of subjects: young adults with normal hearing, elderly persons with presbyacusis, elderly persons with presbyacusis and marked dichotic deficits, and patients with lesions of the corpus callosum. RESULTS: In comparison with the young group the two elderly groups showed an increasing left-ear deficit on the verbal task, and an increasing right-ear deficit on the nonverbal paradigm. The pattern of results obtained in the elderly persons with marked dichotic deficits was similar to the pattern of results in the group with callosal lesions. CONCLUSIONS: With age, there may be a significant loss of efficiency of interhemispheric transfer of auditory information through the corpus callosum. Such age-related deficit might have important implications for the effective use of binaural information by elderly person.

Adolescent↗
PubMed1992

A role for the Na/K-ATPase in the control of human c-fos and c-jun transcription.

The c-fos proto-oncogene is known to be regulated by a variety of hormones, growth factors, and other conditions that alter cellular metabolism. The regulation of c-fos RNA concentrations is known to occur both by altered RNA half-life and/or changes in the transcription rate of the gene. In most cases thus far investigated, induction of c-fos transcription by growth factors occurs very rapidly and transiently. Results presented in this paper show that ouabain, a specific inhibitor of the Na/K-ATPase increases the transcription of c-fos, as well as c-jun, in a variety of cultured cells. However, in contrast to other agents that induce c-fos and c-jun expression, the increased transcription rate of these genes in the presence of ouabain required several hours and remained elevated for at least 16 h. NIH 3T3 cells that have been transfected with deletions of the human c-fos promoter have enabled us to define at least two elements within the promotor that are regulated by ouabain. These include the serum response element and a region between 123 and 222 base pairs 5' to the start site of transcription. We speculate that regulation of the intracellular ion balance through changes in Na/K pump activity may be a general mechanism by which basal transcriptional activity of c-fos is modulated.

3T3 Cells↗
PubMed1991

FMRFamide-like immunoreactivity in cells and fibers of the holothurian nervous system.

Immunoreactivity to FMRFamide (FMRFa) was detected in several components of the nervous system of the sea cucumber, Holothuria glaberrima. Neurons and fibers expressing immunoreactivity to this peptide were found in the radial nerves, and in nerve plexuses of the esophagus, and large and small intestine. The neurons in the enteric nervous system were located in the serosal layer and immunoreactive fibers appeared to innervate the longitudinal muscle. Co-existence of immunoreactivities to FMRFa and cholecystokinin was detected in most of the enteric fibers. Therefore, in the holothurians, neurons expressing FMRFa and FMRFa/cholecystokinin might be involved in the physiology of the digestive tract.

Animals↗
PubMed1991

A prospective randomized study of cerebrospinal fluid drainage to prevent paraplegia after high-risk surgery on the thoracoabdominal aorta.

This article is concerned with the study of the effect of several variables, principally that of cerebrospinal fluid drainage, on the incidence of neurologic deficit in a prospective randomized series of patients with extensive aneurysms of the descending thoracic and abdominal aorta (thoracoabdominal type I and II). Forty-six patients had cerebrospinal fluid drainage, and 52 were controls, with a total of 98 available for study. Cerebrospinal fluid pressure was continuously monitored in the former group and pressure maintained less than or equal to 10 mm Hg in 20, less than or equal to 15 mm Hg in 20, and greater than 15 mm Hg in 6 patients during period of aortic clamping. The method of treatment including reattachment of intercostal and lumbar arteries (p = 0.2), temporary atriofemoral bypass during aortic occlusion (p = 0.3), and spinal fluid drainage (p = 0.8) were not statistically significant in reducing the incidence of neurologic deficits. Thus cerebrospinal fluid drainage as we used it, was not beneficial in preventing paraplegia. On appropriate statistical analysis we found that the only significant predictor of delayed deficits was postoperative hypotension (p = 0.006).

Aortic Dissection↗
PubMed1990

Spinal cord ischemia after resection of thoracoabdominal aortic aneurysms: MR findings in 24 patients.

MR images of the thoracic spinal cord were made in 24 patients who developed signs and symptoms of spinal cord ischemia or infarction following surgery for a thoracoabdominal aortic aneurysm. Findings consisted primarily of four different patterns of signal abnormalities in the distribution of the anterior spinal artery. These abnormalities were identified as types A-D, depending on the degree of involvement of the gray matter and surrounding white matter. We found good correlation between the distribution of the signal abnormalities in the cord, the severity of the neurologic deficits, and the clinical outcome. MR is the imaging method of choice for diagnosing spinal cord ischemia or infarction. A thorough knowledge of the spinal cord arterial territories is crucial for characterizing ischemic MR signal abnormalities and for differentiating them from other causes of myelopathy.

Adolescent↗