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Biomedical subjects

P Ruiz

Publications and source records attributed to P Ruiz.

At least 91 records · Page 5Linked to original sources
PubMed2001

Treatment advances for cocaine-induced ischemic stroke: focus on dihydropyridine-class calcium channel antagonists.

OBJECTIVE: The authors reviewed the pathogenesis of cocaine-related cerebral ischemia, appraised current knowledge of its sequelae, and assessed the role of putative therapeutic agents, particularly dihydropyridine-class calcium channel antagonists. METHOD: The authors performed an OVID-based literature review of all indexed journals between 1966 and 2000. RESULTS: Cocaine abuse significantly increases the risk of ischemic stroke. The principal mechanism of cocaine-induced cerebral ischemia is vasospasm of large cranial arteries or within the cortical microvasculature. Increased levels of extracellular monoamines, particularly dopamine, mediate vasospasm. Neuroanatomical and labeling studies also have shown that dopamine-innervated neurons may regulate cerebral blood flow. Indeed, dopamine-rich brain regions appear to be relatively specific targets for cocaine-induced cerebral ischemia. Neuroimaging studies show that cocaine-induced hypoperfusion can persist even after 6 months of abstinence. Hypoperfusion can result in deficits on complex and simple psychomotor tasks but perhaps not on memory or attention. Severe cerebral ischemia can directly precipitate neuronal death and degradation, a condition exacerbated by liberation of the excitatory amino acid glutamate. Dihydropyridine-class calcium channel antagonists inhibit cocaine-mediated dopamine release on neurons involved in vasospasm and the control of cortical circulation. Other causes of cerebral ischemia include thrombogenesis and vasculitis. Although antithrombotic agents have potential in alleviating cocaine's neurotoxic effects, their use may be limited by the risk of spontaneous hemorrhage. CONCLUSIONS: Cocaine abuse can result in stroke, neuroischemia, and cognitive deficits that can persist even after prolonged abstinence. Dihydropyridine-class calcium channel antagonists, such as isradipine, show promise as therapeutic agents for preventing cocaine-induced cerebral ischemia.

Brain Ischemia↗
PubMed2000

FK409, a spontaneous nitric oxide releaser, attenuates allograft vasculopathy in a rat aortic transplant model.

Although systemic administration of NO donors has been shown to attenuate the development of neointimal hyperplasia in the balloon injury model, this strategy has not been tested in a model of allograft vasculopathy. In this study, we investigated the effect of FK409, a spontaneous NO releaser, on the development of allograft vasculopathy, using a rat aortic transplant model. Thoracic aortas from ACI rats were transplanted heterotopically into the abdominal aorta of Wistar-Furth rats. Postoperatively, recipients received FK409 orally every 8 hours from the day of transplantation to the time of euthanization. Morphometric and immunohistochemical analyses were performed on the aortic grafts 8 weeks after transplantation. Control allografts showed severe neointimal hyperplasia, which consists mainly of alpha-actin-containing vascular smooth muscle cells. The FK409-treated allografts showed a dose-dependent reduction (statistically significant compared with the control) in the neointimal thickness as the dose increased from 1 to 10 mg/kg (thrice per day). However, there was no significant difference in the neointimal thickness between groups treated with 10 and with 20 mg/kg. FK409 treatment (10 mg/kg) caused a significant decrease in DNA synthesis (5-bromo-2-deoxyuridine [BrdU] uptake), an increase in DNA fragmentation (terminal deoxynucleotidyltransferase-mediated uridine nick-end labeling [TUNEL]), and upregulation of Fas expression, in the neointimal vascular smooth muscle cells. These data suggest that FK409 attenuates the allograft vasculopathy in a rat aortic transplant model.

Animals↗
PubMed2000

Modulation of renal disease in MRL/lpr mice genetically deficient in the alternative complement pathway factor B.

In systemic lupus erythematosus, the renal deposition of complement-containing immune complexes initiates an inflammatory cascade resulting in glomerulonephritis. Activation of the classical complement pathway with deposition of C3 is pathogenic in lupus nephritis. Although the alternative complement pathway is activated in lupus nephritis, its role in disease pathogenesis is unknown. To determine the role of the alternative pathway in lupus nephritis, complement factor B-deficient mice were backcrossed to MRL/lpr mice. MRL/lpr mice develop a spontaneous lupus-like disease characterized by immune complex glomerulonephritis. We derived complement factor B wild-type (B+/+), homozygous knockout (B-/-), and heterozygous (B+/-) MRL/lpr mice. Compared with B+/- or B+/+ mice, MRL/lpr B-/- mice developed significantly less proteinuria, less glomerular IgG deposition, and decreased renal scores as well as lower IgG3 cryoglobulin production and vasculitis. Serum C3 levels were normal in the B-/- mice compared with significantly decreased levels in the other two groups. These results suggest that: 1) factor B plays an important role in the pathogenesis of glomerulonephritis and vasculitis in MRL/lpr mice; and 2) activation of the alternative pathway, either by the amplification loop or by IgA immune complexes, has a prominent effect on serum C3 levels in this lupus model.

Animals↗
PubMed2000

Systemic lupus erythematosus in mice, spontaneous and induced, is associated with autoimmunity to the C-terminal domain of p53 that recognizes damaged DNA.

The tumor suppressor molecule p53 features a regulatory domain at the C terminus that recognizes damaged DNA. Since damaged DNA might be involved in activating anti-DNA autoantibodies, we tested whether autoimmunity to the C terminus of p53 might mark murine systemic lupus erythematosus (SLE). We now report that MRL / MpJ-Fas(lpr) mice, which spontaneously develop SLE, produce antibodies both to the C terminus of p53 and to a monoclonal antibody (PAb-421) that binds the p53 C terminus. Anti-idiotypic antibodies to PAb-421 (sampled as monoclonal antibodies) could also bind DNA. Thus, the PAb-421 antibody mimics DNA, and the anti-idiotypic antibody to PAb-421 mimics the p53 DNA-binding site. This mimicry was functional; immunization of BALB / c mice to PAb-421 induced anti-DNA antibodies and antibodies to the C terminus of p53, and most of the mice developed an SLE-like disease. Immunization of C57BL / 6 mice to PAb-421 induced antibodies to p53, but not to its C-terminal domain. The C57BL / 6 mice also did not develop anti-DNA antibodies or the SLE-like disease. Thus, network autoimmunity to the domain of p53 that recognizes damaged DNA can be a pathogenic feature in SLE in genetically susceptible strains of mice.

Animals↗
PubMed2000

Quality of life measures in the Miami HIV-1 infected drug abusers cohort: relationship to gender and disease status.

PURPOSE: This study examined activity, daily living, health, support, and outlook in HIV+ drug users. METHODS: Using the physician-administered Spitzer Index, the study assessed 75 HIV-1 seropositive men (n = 51) and women (n = 24) enrolled in the Miami HIV-1 Infected Drug Abusers Study (MIDAS). RESULTS: Total composite scores were significantly lower in the HIV-1 infected women than the men (p = .03). Significant gender differences were observed in activity assessment, independent of disease status, with women six times as likely to have lower activity scores (p = .0038). Most women (45%) in this category were homeless or marginally housed, compared to 11 percent of the men. Additionally, women with low activity scores had less social support than women with high activity scores. Cocaine use was significantly related to reports of normal activity, and varied across genders; more men used cocaine than women (p = .03). Compared to non-AIDS participants, AIDS patients were more likely to have lower scores in health (p = .009) and poorer outlook (p = .03). IMPLICATIONS: These findings reveal specific deficits in areas of psychosocial capacity, particularly in HIV-1 infected women who abuse drugs, that may need to be strengthened in order to enhance function and adherence to treatment, as well as well-being.

Activities of Daily Living↗
PubMed2000

Experimental discordant hepatic xenotransplantation in the recipient with liver failure: implications for clinical bridging trials.

BACKGROUND: Clinical xenotransplantation might start with bridge-to-bridge trials. Situations where hyperacute rejection is avoided would provide opportunities for the initiation of bridging trials. Patients with liver failure have a diminished capacity to initiate antibody and complement-induced injury of xenogeneic endothelium. Hyperacute rejection of a liver xenograft manifests as a coagulopathy. We examined the ability of a recipient with liver failure to hyperacutely reject a liver xenograft in the dog-to-pig model in the immediate postoperative period. STUDY DESIGN: Liver failure in pigs was induced with galactosamine. Canine livers were transplanted into pigs with liver failure and into healthy pigs. The postoperative course was monitored for 1 hour for histologic changes in the xenograft, changes in platelet counts, and whole blood clotting with Sonoclot analysis. In vitro assays with pig serum and canine hepatic sinusoidal endothelial cells were used to assess the effect of liver failure on serum cytotoxicity and xenoreactive antibody levels. RESULTS: All untreated pig recipients of liver xenografts died from a coagulopathy. Recipients with liver failure manifested no signs of coagulopathy, and had minimal change in platelet counts or Sonoclot (Sienco Inc., Morrison, CO) tracings. Liver xenograft biopsies from recipients with liver failure showed no evidence of the tissue injury that characterized the biopsies of control recipients. Serum from pigs was less cytotoxic to the canine hepatic sinusoidal endothelium after induction of liver failure. The xenoreactive antibody levels and repertoire were similar in the pig serum before and after liver failure was induced. CH50 (total complement) levels were diminished in pigs after the induction of liver failure. CONCLUSIONS: Liver xenotransplantation used in bridging trials in recipients with liver failure might not face the barrier of hyperacute rejection.

Animals↗
PubMed2000

Is there a special relationship between CD30-positive lymphoproliferative disorders and epidermal proliferation?

The relationship between CD30+ lymphoma and epithelial proliferations is not well defined. CD30+ lymphoma and lymphomatoid papulos (LyP) share immunohistochemical epitopes and some other features. A single case of LyP associated with multiple keratoacanthomas (KAs) was recently reported. We report two cases of atypical lymphocytic proliferation with features of CD30+ lymphoma and LyP intimately associated to KA and squamous cell carcinoma (SCC), KA type. This similar combination of an epidermal tumor and apparent involvement with atypical lymphocytic infiltrates raises the possibility of an association between the two entities. We speculate that the association may be more than expected to occur by chance and suggest several mechanisms by which the association may evolve.

Aged↗
PubMed2000

A role for leukotrienes in cyclosporine nephrotoxicity.

BACKGROUND: Nephrotoxicity associated with cyclosporine A (CsA) administration is characterized by marked renal vasoconstriction, interstitial fibrosis, and arteriolar hypertrophy. While the molecular mechanisms of CsA toxicity are not well characterized, previous studies have demonstrated that altered arachidonic acid (AA) metabolism plays a role its pathogenesis. Using a rat renal transplant model, the purpose of this study was to examine the effects of CsA on the 5-lipoxygenase (5-LO) pathway of AA metabolism. METHODS: The PVG (RT1c) strain of rats underwent kidney transplantation, and recipients of nonrejecting kidney transplants were treated with either 50 mg/kg/day CsA or vehicle (N = 24). To determine the physiologic significance of increased leukotriene (LT) production, the peptidoleukotriene receptor antagonist SKF 106203 was administered to CsA-treated animals for six days. RESULTS: CsA caused a substantial reduction in glomerular filtration rate (GFR) in the transplanted rats compared with the vehicle-treated controls (1.5 +/- 0.6 vs. 4.1 +/- 0.8 mL/min/kg, P < 0.05). The reduction in renal function was associated with enhanced urinary excretion of the peptidoleukotriene metabolites LTE4 (1431 +/- 207 vs. 953 +/- 125 pg/24 h, P < 0.05) and N-acetyl-LTE4 (4411 +/- 848 vs. 463 +/- 70 pg/24 h, P < 0.001). LT receptor blockade had a significant protective effect on renal transplant function in CsA-treated animals (GFR, 4.8 +/- 1.1 vs. 1.7 +/- 0.9 mL/min/kg, P < 0.05), such that CsA-treated animals that received SKF106203 maintained GFR at levels similar to controls that never received CsA (4.1 +/- 0.8 mL/min/kg). Peptidoleukotriene receptor blockade also prevented the histomorphological abnormalities caused by CsA, including tubular vacuolization. CONCLUSIONS: These studies identify a critical role for LTs in the pathophysiology of CsA nephrotoxicity and suggest that LT antagonists may be useful in preventing CsA-associated kidney toxicity.

Animals↗
PubMed2000

E-cadherin and adenomatous polyposis coli mutations are synergistic in intestinal tumor initiation in mice.

BACKGROUND & AIMS: Inactivation of the adenomatous polyposis coli (APC) gene is observed at early stages of intestinal tumor formation, whereas loss of E-cadherin is usually associated with tumor progression. Because both proteins compete for the binding to beta-catenin, an essential component of the Wnt signaling pathway, reduction of E-cadherin levels in an Apc mouse model could influence both tumor initiation and progression. In addition, loss or haploinsufficiency of E-cadherin may affect tumorigenesis by altering its cell-adhesive and associated functions. METHODS: Apc1638N mice were bred with animals carrying a targeted E-cadherin knockout mutation. RESULTS: Double heterozygous animals showed a significant 9-fold and 5-fold increase of intestinal and gastric tumor numbers, respectively, compared with Apc1638N animals. The intestinal tumors of both groups showed no significant differences in grading and staging. Loss of heterozygosity analysis at the Apc and E-cadherin loci in both intestinal and gastric Apc(+/1638N)/E-cad(+/-) tumors revealed loss of the wild-type Apc allele in most cases, whereas the wild-type E-cadherin allele was always retained. This was supported by a positive, although reduced, staining for E-cadherin of intestinal tumor sections. CONCLUSIONS: Introduction of the E-cadherin mutation in Apc1638N animals enhances Apc-driven tumor initiation without clearly affecting tumor progression.

Adenomatous Polyposis Coli Protein↗
PubMed2000

Age of onset as a discriminator between alcoholic subtypes in a treatment-seeking outpatient population.

Subtyping alcoholics may provide a more accurate guide as to the course and character of the disease. Classifications of different ages of onset of problem drinking have so far resulted in categorical inconsistencies. In the past, hospital-based alcoholics have over-represented those most severely ill, and comprehensive evaluations of psychopathology for discriminating between alcoholic subtypes have been infrequent. In a heterogeneous treatment-seeking, outpatient, alcoholic population, we tested the hypothesis that age of onset represents a continuum of disease, and that greater severity of psychopathology is associated with lower ages of onset. Using a standard questionnaire, 253 male and female treatment-seeking alcoholics were stratified according to specific ages of onset: a) < 20 years; b) 20-25 years, and c) > 25 years. These age of onset groups were compared on alcohol severity and craving, family history, childhood behavior, personality, hostility, overt aggression, mood, and social functioning. Symptom severity and age of onset were negatively correlated, and the 20-25-year onset group usually had intermediate scores. The < 20 year onset group was characterized by greater severity of alcohol-related problems, family history, childhood behavioral problems, craving, hostility, antisocial traits, mood disturbance, and poor social functioning. Alcoholics with an earlier age of onset have relatively greater psychopathology than those of later onset. While the preponderance of psychopathology among those in the < 20-year onset group could be conceptualized as a clinical "subtype," such a characterization would not define an entirely homogeneous category. Yet, this clinical characterization would be clinically important if specific age of onset levels were found to be differentially sensitive to pharmacological and/or psychological treatments.

Adult↗
PubMed2000

Psychiatric considerations in the diagnosis, treatment, and prevention of HIV/AIDS.

HIV/AIDS has the unfortunate distinction of being one of the most devastating epidemics of the twentieth century. By the end of June, 1999, 420,201 deaths in persons with AIDS had been reported in the United States. While HIV/AIDS patients are currently living longer as a result of more effective and complex treatments, no vaccination or cure has yet been discovered. Over the years, the HIV/AIDS epidemic has become multifactorial and currently affects several different special population groups. Individuals who are at high risk for becoming infected with HIV or who already suffer from HIV/AIDS can benefit greatly from the interventions of psychiatrists or other mental health professionals. It is important that psychiatrists collaborate very closely with infectious disease specialists in the management of HIV/AIDS and its psychological sequelae. The authors describe the psychiatric conditions that most often occur in association with HIV/AIDS: mood disorders, anxiety disorders, substance-related disorders, psychotic disorders, insomnia and sleep disorders, delirium, dementia, and pain syndromes. We present guidelines for diagnosis and psychopharmacological and psychotherapeutic treatment of these disorders in patients with HIV/AIDS. The article concludes with a discussion of prevention strategies that can be used in a mental health treatment setting and special issues related to treating HIV/AIDS in certain special population groups.

Journal Article↗