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Biomedical subjects

J Rivero

Publications and source records attributed to J Rivero.

At least 19 recordsLinked to original sources
PubMed2004

Effect of cervical spinal cord stimulation on regional blood flow and oxygenation in advanced head and neck tumours.

BACKGROUND: Tumour ischaemia leads to decreased delivery of oxygen, chemotherapy and radiosensitisers. Hypoxia in head and neck (H&N) tumours is an important adverse prognostic factor. Spinal cord stimulation (SCS) is a well-established neurosurgical technique in the treatment of several ischaemic syndromes. This prospective study evaluated the effect of cervical-SCS on common carotid artery (CCA) blood flow and tumour oxygenation in patients with advanced H&N cancer. PATIENTS AND METHODS: Sixteen patients with advanced H&N tumours were enrolled. Cervical-SCS devices were inserted subcutaneously prior to commencement of scheduled chemoradiotherapy. Pre- and post-SCS measurements were as follows: (i) tumour oxygenation (mmHg) using polarographic probes; (ii) blood flow quantification (ml/min) and diastolic and systolic velocimetry (cm/s) in the CCA using colour Doppler. RESULTS: After SCS, median tumour oxygenation increased in two-thirds of patients (34%; P = 0.023), all patients had improved CCA blood flow (50%; P <0.001) and almost all patients showed an increased CCA diastolic velocity (26%; P = 0.003) and systolic velocity (20%; P = 0.011). CONCLUSIONS: Cervical-SCS increased tumour oxygenation and CCA blood flow, and could enhance the loco-regional delivery of oxygen, radiosensitising and chemotherapeutic drugs. Cervical-SCS as adjuvant in chemoradiotherapy of these tumours warrants further investigation.

Adult↗
PubMed2001

Chimeric synthetic peptides from the nucleocapsid p24 protein of human immunodeficiency virus type-1.

Two chimeric synthetic peptides incorporating antigenic sequences from N-terminal (peptide C14) (134-163) and C-terminal (peptide C15) (335-364) of the p24 protein of human immunodefiency virus (HIV- 1), were synthesized. Peptides C14-GG-C15 and C15-GG-C14 represented sequences from the p24 protein in both possible orders, separated by two glycine residues as arm spacers. These peptides were evaluated as antigen in an Ultramicroenzyme-linked immunosorbent assay (UMELISA) using sera of HIV-1-infected individuals (n = 16) with different titers of antibodies and the specificity was evaluated with healthy blood donors (n = 20). The results were compared to plates coated with monomeric peptides C14 and C15. The chimeric peptide C14-GG-C15 was the most antigenic. Those results may be related to the peptide structure, the sequence order in the chimeric peptide, and epitope accessibility to the antibodies. This chimeric peptide would be very useful for HIV-1 diagnostics.

Amino Acid Sequence↗
PubMed1998

Influence of mechanical ventilation on blood lactate in patients with acute respiratory failure.

OBJECTIVES: To determine whether mechanical ventilation (MV) may affect blood lactate concentration in patients with acute respiratory failure. DESIGN: Prospective observational study with follow-up to hospital discharge. SETTING: A 17-bed medical and coronary intensive care unit in a 650-bed general hospital. PATIENTS: 55 adult patients mechanically ventilated for acute respiratory failure between May 1996 and April 1997 were recruited. MEASUREMENTS AND RESULTS: Arterial blood samples for determination of plasma lactate and blood gas analysis were taken just before tracheal intubation on spontaneous breathing, and 20 and 60 min after the initiation of controlled MV. Cuff systemic arterial pressure was measured before tracheal intubation and every 10 min during the first h of MV. Hyperlactatemia (arterial blood lactate > or = 2 mmol/l) was present in 21 of the 55 patients studied. After 20 min of MV, there was a decrease in blood lactate from 4.74 +/- 1.78 to 3.07 +/- 1.69 mmol/l (p < 0.01); 40 min later there was a further decrease to 2.63 +/- 1.35 mmol/l (p < 0.05). The decrease in blood lactate was also observed in those patients who after starting MV developed systemic arterial hypotension (p < 0.01). In patients with a normal lactate concentration at the entry to the study, lactate remained the same after 60 min on MV (NS). CONCLUSIONS: Controlled MV decreases substantially the severity of hyperlactatemia in patients with acute respiratory failure, and any adverse circulatory effects of MV do not alter this beneficial outcome.

Adult↗
PubMed1998

A recombinant protein based immunoassay for the combined detection of antibodies to HIV-1, HIV-2 and HTLV-I.

The aim of this study was to develop and evaluate a combined assay for the detection of antibodies to HIV-1, HIV-2 and HTLV-I (human T-cell leukemia virus type I). A mixture of recombinant proteins and synthetic peptides was fixed to the surface of microELISA wells and a protein A peroxidase conjugate was used as tracer. The combined assay was compared to specific HIV-1/2 and HTLV-I commercial ELISAs. The sensitivity was studied with a panel of 158 HIV-1, 82 HIV-2 and 48 HTLV-I positive sera, all of which were reactive in the combined assay. The analytical sensitivity was studied with a panel of serially diluted sera and was similar to that obtained for the specific ELISAs. The specificity of the test was 99.78% against a panel of 466 negative sera collected from voluntary donors that included HBsAg, HCV, and VDRL positive sera. The false positive serum was borderline in the HTLV-I specific ELISA. The new combined ELISA can be used as an efficient initial screening assay, avoiding the cost of individual tests for HIV and HTLV.

AIDS Serodiagnosis↗
PubMed1998

Use of antipsychotic drugs in nursing homes: current compliance with OBRA regulations.

OBJECTIVE: To examine the degree and patterns of compliance with the Omnibus Budget Reconciliation Act (OBRA) regulations regarding the use of antipsychotic drugs in nursing homes. DESIGN: Retrospective chart review of all resident records. PARTICIPANTS: Eight nursing homes: five community, two county-owned, and one university-affiliated Veterans Administration facility. MEASUREMENTS: A structured assessment instrument to track compliance with each aspect of the OBRA regulations regarding antipsychotic drug use. RESULTS: A total of 1573 nursing home residents' pharmacy records were reviewed between August 1994 and March 1996. Two hundred seventy-nine residents were actively taking antipsychotic medications (prevalence = 17.7%). Mean compliance greater than 70% was found for (1) appropriate diagnostic indication (mean = 70.9%), (2) dosage within recommended limits (mean = 90.1%), and 3) documented appropriate target symptoms (mean = 90.4%). Dosages were more likely to exceed limits in those patients with histories of major mental illness, particularly schizophrenia. CONCLUSIONS: Nursing homes were better able to comply with those guidelines that are most specific. Educational interventions now need to focus on behavioral interventions, monitoring of adverse effects, and efficacy. These data are useful in establishing threshold levels of performance and can be used by nursing homes for continuous quality improvement. OBRA continues to impact neuroleptic drug prescribing practices in nursing homes significantly.

Aged↗
PubMed1998

Circulating cell adhesion molecules are correlated with ultrasound-based assessment of carotid atherosclerosis.

Although cellular adhesion molecules (CAMs) are hypothesized to play an important role in atherogenesis, the relationship between CAMs and systemic atherosclerosis is uncertain. Among 92 outpatients (48 men; mean+/-SD age, 65+/-9 years), we evaluated the association of soluble vascular CAM-1 (sVCAM-1) and intercellular adhesion molecule-1 (sICAM-1) with carotid intimal-medial thickness (IMT), an index of early atherosclerosis. All subjects underwent a 2-dimensional ultrasound examination of both carotid arteries at the distal common carotid arteries and bifurcation. sVCAM-1 and sICAM-1 levels measured by enzyme-linked immunosorbent assay were significantly correlated with mean IMT of the common carotid artery (r=0.34 and r=0.30, respectively; P<0.01) and carotid bifurcation (r=0.31 and r=0.26, respectively; P<0.05), whereas sVCAM-1 was also positively associated with maximal carotid IMT (r=0.35, P<0.01). Adjustment for age attenuated the association between sVCAM-1 and common (r=0.16, P=0.13) and bifurcation (r=0.18, P=0.07) carotid IMT but had minimal effect on the associations between sICAM-1 and carotid measurements (r=0.32, P<0.01; r=0.23, P<0.05; for common and bifurcation IMT, respectively). Age-adjusted sICAM-1 levels increased in a stepwise fashion across common carotid IMT tertiles (253+/-27 versus 275+/-24 versus 384+/-26 pg/mL for the lowest, intermediate, and highest IMT tertiles, respectively; P<0.01). A similar trend was also found between sVCAM-1 levels and common carotid IMT tertiles (625+/-60 versus 650+/-53 versus 714+/-58 pg/mL; P<0.15). These associations were minimally affected in analyses adjusting for hypertension, diabetes, smoking, low and high density lipoprotein cholesterol, lipoprotein(a), and homocysteine, or in a subgroup analysis limited to those with no prior history of atherothrombotic disease. These data demonstrate a positive association between serum CAMs with carotid IMT and further support the hypothesis that systemic inflammation may have a role in atherosclerotic lesion development.

Aged↗
PubMed1997

Single point dilution method for the quantitative analysis of antibodies to the gag24 protein of HIV-1.

In the present work a concept proposed in 1992 by Dopotka and Giesendorf was applied to the quantitative analysis of antibodies to the p24 protein of HIV-1 in infected asymptomatic individuals and AIDS patients. Two approaches were analyzed, a linear model OD = b0 + b1.log(titer) and a nonlinear log(titer) = alpha.OD beta, similar to the Dopotka-Giesendorf's model. The above two proposed models adequately fit the dependence of the optical density values at a single point dilution, and titers achieved by the end point dilution method (EPDM). Nevertheless, the nonlinear model better fits the experimental data, according to residuals analysis. Classical EPDM was compared with the new single point dilution method (SPDM) using both models. The best correlation between titers calculated using both models and titers achieved by EPDM was obtained with the nonlinear model. The correlation coefficients for the nonlinear and linear models were r = 0.85 and r = 0.77, respectively. A new correction factor was introduced into the nonlinear model and this reduced the day-to-day variation of titer values. In general, SPDM saves time, reagents and is more precise and sensitive to changes in antibody levels, and therefore has a higher resolution than EPDM.

Enzyme-Linked Immunosorbent Assay↗
PubMed1997

Incidence of dehiscences in the fallopian canal.

Fifty human temporal bones from necropsies were used to study the frequency of canal dehiscences in detail along the course of the facial nerve. Specifically, the study focused on bony dehiscences in the fallopian canal and vascular communications between the facial nerve and the surrounding bone. High frequency of dehiscences at the oval window (60%) and in the pyramidal segment (54%) were found. These dehiscence rates are in agreement with published reports. A 20% rate of dehiscences at the most anterior segment of the tympanic segment was noted and a non-reported high rate (20%) of multiple dehiscences along the course of the fallopian canal in the same temporal bone in specimens of newborns and young children. The significance of these findings in terms of clinical implications is discussed.

Adolescent↗
PubMed1997

Long-term treatment with recombinant interferon alpha-2b prolongs survival of asymptomatic HIV-infected individuals.

RATIONALE AND OBJECTIVE: Early long-term treatment with recombinant interferon (IFN) alpha-2b delayed disease progression in asymptomatic Human Immunodeficiency Virus (HIV) carriers in a randomized trial that lasted from October 1987 to February 1992 (14). The aim of the work reported in this paper was to observe if there was also an effect on survival when the same patients were followed-up further. DESIGN AND INTERVENTIONS: IFN alpha-2b was given 3 x 10(6) IU, 3 times weekly. The control group did not receive any treatment. The main end-point for this evaluation was death due to any cause. The deadline was August 1995. POPULATION: Subjects were anti-HIV-1 seropositive, Western blot-confirmed, asymptomatic (CDC group II), or with generalized lymphadenopathies (CDC group III). The groups had 79 (control) and 83 (IFN) patients. MAIN RESULTS: Mean survival was longer in the IFN group (95% CI: 127-152 vs. 101-120 months since infection or 80-90 vs. 70-82 months since the start of treatment). Survival rates were higher in IFN-treated individuals (61-77% vs. 24-54% at 10 years of infection or 53-69% vs. 34-52% at 7 years of treatment or follow-up). It was also confirmed that disease progression is significantly slower in IFN-treated patients. There were 23.4 vs. 3.2% long-term survivors in the IFN and control groups, respectively (p = 0.005). IFN-treated patients had fewer AIDS-related malignancies (5 vs. 11), mainly Kaposi's sarcomas (1 vs. 5). This difference was not statistically significant, but clinically interesting. There was no difference in survival if measured since the onset of AIDS. CONCLUSION: IFN alpha treatment given from the early stages of infection, but not after the appearance of AIDS symptoms, can prolong survival.

Adult↗
PubMed1997

Cytotoxicity of a low molecular weight fraction from Aloe vera (Aloe barbadensis Miller) gel.

The cytotoxicity of a low mol. wt fraction (LMWF) obtained from Aloe vera gel was determined by two different assays. Firstly, exposure of monolayers of chicken fibroblasts to LMWF induced disruption of intercellular junctions and detachment of individual cells from the bottom of the flask, with formation of cell-free gaps in the monolayer. Secondly, LMWF inhibited the production of reactive oxygen species by human polymorphonuclear leukocytes stimulated by zymosan, as followed by luminol-dependent chemiluminescence. The toxic activity of LMWF was compared to that of sodium dodecyl sulfate (a well-known toxic substance), aloe-emodin and aloin (an anthraquinone and its precursor present in Aloe vera cortex) using the chemilumescence assay, and was found to be of similar potency to these toxic substances on a weight-to-weight basis. These results confirm that Aloe vera gel contains toxic low mol. wt compounds, and every effort must be made to limit the amount of these toxins in the commercially prepared Aloe vera gel products.

Aloe↗
PubMed1997

[Follow-up serological study of herpes simplex and cytomegalovirus in Cuban patients infected with human immunodeficiency virus (HIV)].

The evolution serological response against the herpes simplex virus and citomegalovirus in HIV infected patients grouped into different stages of the disease was studied. Fluctuations in the TPG of antibodies were observed in these values in a cyclical way through time. There was a greater significant difference among the TPG of antibodies against HSV in the group of asymptomatic patients compared with AIDS patients and with those who died. There is a marked decrease in the TPG of antibodies against HSV and CMV approximately one year before the death of patients.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Histological structure of the vocal fold in the human larynx.

Histological analysis of the human vocal folds, focused particularly on the lamina propria of the vocal muscle of fetuses, infants, and adults in horizontal laryngeal sections, allowed us to show the differences in morphology and composition according to the laryngeal development. Our results indicate that the origin of the vocal fold is independent of the origin of the other portions of the larynx, and the influence of the zone known as macula flava in the maturation of the vocal fold is an age-related process.

Adult↗
PubMed1995

Clinicopathologic study of probable Alzheimer disease: assessment of criteria for excluding cerebrovascular disease.

The National Institute of Neurological and Communicative Disorders and Stroke/Alzheimer Disease and Related Disorders Association criteria for probable Alzheimer disease (AD) require exclusion of non-AD dementia-producing conditions but do not specify how the non-AD conditions are to be identified. We addressed this issue for the case of cerebrovascular disease (CVD) by defining exclusion rules based on commonly described clinical features: (a) history of strokelike episodes; (b) history of stepwise cognitive decline; (c) focal deficits on neurological examination; and (d) evidence of significant CVD on neuroimaging. We applied these rules retrospectively to clinical records for 92 cognitively impaired patients who otherwise met criteria for probable AD and whose brains were subsequently available for postmortem examination. We used Fisher's exact test to assess the effectiveness of the exclusion rules in predicting the presence of CVD on autopsy. Prediction was better than chance when all four clinical features were used together (p = 0.0008) and when the stepwise decline or neuroimaging criteria were used alone (p = 0.03 and p = 0.05, respectively). Overall, the CVD exclusion rules were deficient because of low accuracy (50.0%) and low sensitivity (52.6%). These results support provisional use of the CVD criteria chosen for this study but suggest that modifications are needed for acceptable diagnostic accuracy and sensitivity to be achieved.

Alzheimer Disease↗