PubMed Health⌕ Search

Biomedical subjects

C A Rodríguez

Publications and source records attributed to C A Rodríguez.

18 recordsLinked to original sources
PubMed2006

In situ study of the relevance of bacterial adherence to feed particles for the contamination and accuracy of rumen degradability estimates for feeds of vegetable origin.

An in situ study was conducted on four rumen-cannulated wethers to determine (using (15)N infusion techniques) the microbial contamination (mg bacterial DM or crude protein (CP)/100 mg DM or CP) and the associated error on the effective degradability of fourteen feeds: barley and maize grains, soyabean and sunflower meals, full-fat soyabean, maize gluten feed, soyabean hulls, brewers dried grains, sugarbeet pulp, wheat bran, lucerne and vetch-oat hays, and barley and lentil straws. The DM or CP contamination in residues (M) fitted to single exponential or sigmoid curves. A general model (M=m (1-e(-ft) ) (j)) was proposed to match this fit. Asymptotic values (m) varied from 2.84% to 13.3% and from 2.85% to 80.9% for DM and CP, respectively. Uncorrected results underestimated the effective degradability of both DM (P<0.05) and CP (P<0.01). For CP, this underestimation varied from 0.59 % to 13.1%, with a higher but unascertainable error for barley straw. Excluding maize grain, the microbial contamination of both DM and CP, and the associated underestimation of the effective degradability of CP, were positively related to the cellulose content of the feed. The error in the effective degradability of CP was also negatively related to the CP content and its apparent effective degradability (R(2) 0.867). This equation allows easier and more accurate estimates of effective degradability, needed to improve protein-rationing systems.

Animal Feed↗
PubMed2003

Screening of antimutagenicity via antioxidant activity in Cuban medicinal plants.

The reducing activity on the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, z.rad;OH radical scavenging potential, in vitro inhibition of lipid peroxidation and modulation of mutagenicity induced by ter-butyl hydroperoxide (TBH) in Escherichia coli were sequentially screened in 45 species of plants used with medicinal purposes in Cuba, in a search for antioxidant agents which protect DNA against oxidative stress.Five species, e.g. Tamarindus indica L., Lippia alba L., Pimenta dioica (L.) Merr, Rheedia aristata Griseb. and Curcuma longa L. displayed IC(50)<30 micro g/ml in the DPPH radical reduction assay and IC(50)<32 micro g/ml in lipid peroxidation inhibition testing. Pimenta dioica and Curcuma longa L. showed also a 20% inhibition of the in vitro induced z.rad;OH attack to deoxyglucose. Further antimutagenesis assay in Escherichia coli IC 188 evidenced that only Pimenta dioica prevents DNA damage by TBH to the test bacteria. A role of antioxidant enzymes is presumed in this case, as judged by a different response in the isogenic Escherichia coli IC 203 deficient in catalase and alkyl hydroperoxide reductase and the discrete inhibition of oxidative mutagenesis also observed when pre-treatment of the extract was assayed. Eugenol, the main constituent of the essential oil of Pimenta dioica, also inhibited oxidative mutagenesis by TBH in Escherichia coli, at concentrations ranging from 150 to 400 micro g/plate.

Antimutagenic Agents↗
PubMed2003

Effects of feed intake on composition of sheep rumen contents and their microbial population size.

The present study was conducted to determine the effect of feed intake on the composition of the rumen contents of sheep and on their bacterial densities. Whole rumen contents were sampled after a period of continuous inter-rumen infusion of 15NH3 from four rumen-cannulated wethers successively fed on a hay-concentrate diet (2:1, w/w on a DM basis) at two rates of feed intake: 40 and 80 g DM/kg body weight0.75. Total weight and chemical composition of rumen contents, as well as the distribution by size and chemical composition of particles, were determined. The populations of bacteria associated with the liquid (liquid-associated bacteria, LAB) and solid (solid-associated bacteria, SAB) fractions of rumen digesta and the distribution of SAB according to feed particle size were also examined. The greater feed intake caused an increase in the mass of the rumen contents, while its chemical composition did not change, except for a higher content of organic matter (P=0.023). The distribution of feed particles by size was similar at both levels of intake. The concentrations of neutral- and acid-detergent fibre in feed particles decreased and those of total, dietary, and microbial N increased, both with a quadratic response (P=0.001), as particle size decreased. The proportion of LAB in the microbial biomass of rumen digesta reached only 8.0 %. This proportion and the density of LAB were unaffected by the level of feed intake, whereas an apparent reduction (10.4 %) occurred with the SAB biomass in whole rumen contents. A systematic, but not significant, reduction (mean value 11.9 %) in the level of microbial colonisation in the different particle fractions with the increase of feed intake was also observed.

Animal Nutritional Physiological Phenomena↗
PubMed2000

Composition of bacteria harvested from the liquid and solid fractions of the rumen of sheep as influenced by feed intake.

A study was conducted to determine the effect of the feed intake on the chemical composition of bacteria associated with the solid (solid-associated bacteria; SAB) and liquid (liquid-associated bacteria; LAB) fractions of rumen digesta, the digestive passage kinetics and their relationships. Whole rumen contents were sampled after a period of continuous infusion of 15NH3 from four ruminally-cannulated wethers provided successively with a hay-concentrate diet (2 : 1 w/w on a DM basis) at two rates of feed intake: 40 and 80 g DM/kg body weight 0.75. SAB had a higher content of organic matter and total lipids (P < 0.001) and a similar N content as compared with LAB. The concentration of purines and 15N was lower (P = 0.011 and P < 0.001 respectively) in SAB than LAB, whereas the opposite was observed for the concentration of amino acids (mg/g DM; P = 0.031). An increase in feed intake produced an increase in the N (P = 0.034) and purine (P = 0.066) concentrations in bacteria and a decrease (P = 0.033) in their amino acid concentrations. Significant increases of rumen outflow rates of liquid and particles were also observed with increased feed intake. Rates of rumen outflow showed positive and negative linear relationships (P < 0.001) with the purine : N ratio and the proportion of amino acid on total N of bacteria respectively. SAB contained significantly higher proportions of leucine, isoleucine, lysine and phenylalanine and lower proportions of alanine, methionine and valine than LAB. The increase in feed intake also induced significant changes in the amino acid profile of bacteria, increasing arginine and methionine and decreasing alanine and glycine proportions. Results show that the outflow rate of rumen contents is a major factor in determining the proportion of nucleic acids and protein in rumen bacteria and explains some of the differences observed between LAB and SAB.

Amino Acids↗
PubMed1999

Venous irritation, pharmacokinetics, and tissue distribution of tirilazad in rats following intravenous administration of a novel supersaturated submicron lipid emulsion.

PURPOSE: To compare the venous irritation, pharmacokinetics, and tissue distribution of tirilazad in rats after intravenous administration of a submicron lipid emulsion with that of an aqueous solution. METHODS: Venous irritation was determined by microscopic evaluation of injury to the lateral tail veins of rats. Pharmacokinetic parameters were determined by following plasma concentrations of drug. Tissue distribution of [14C]-tirilazad was determined by quantitative whole body autoradiography. RESULTS: Single dose injections of tirilazad as an emulsion at doses ranging from 1.52 mg to 13.5 mg were non-irritating whereas the solution was irritating at a dose of 1.3 mg. The pharmacokinetic parameters were not statistically different between the emulsion and the solution (p > 0.2) at doses of 6 mg/kg/day and 20 mg/kg/day. However, at 65 mg/kg/day dose, a higher AUC(0,6) (4-fold) and lower V(ss), (18-fold) and CL(5-fold) were observed for the lipid emulsion as compared to the solution (p < 0.05). Tissue distribution showed higher initial concentrations (two fold or more) in most tissues for the solution. These values, however, equilibrated by 4 h and AUC(0,4) differences were less than two fold in most tissues. CONCLUSIONS: Formulating tirilazad in the lipid emulsion significantly reduces the venous irritation without changing the pharmacokinetics and tissue distribution at low doses.

Animals↗
PubMed1997

[Sequential chemotherapy and radiotherapy in the treatment of locally advanced carcinoma of the head and neck].

In patients with non-resectable carcinoma of the head and neck, radiotherapy produces an average survival of 12 months. Neoadjuvant chemotherapy followed by radiotherapy has been shown to prolong survival and preserve organ structure and function, and to reduce systemic relapses in patients with advanced, resectable disease. An analysis was made of 35 patients treated with sequential chemotherapy and radiotherapy, 20 with non-resectable disease and 15 with resectable disease who refused surgery. Treatment consisted of 4 cycles of cisplatin + 5-fluoruracil in a 96-h continuous intravenous infusion in 16 patients, and the same treatment with leucovorin in 19 patients. After chemotherapy, the patients underwent cobalt irradiation of the primary tumor and neck. Chemotherapy produced a complete response rate of 46% and a partial response rate of 28%, yielding an overall rate of 74%. After radiotherapy, the CR increased to 63%. After 92 months of maximum follow-up, overall survival was 20% and median survival was 25 months. Locoregional relapses were the main cause of treatment failure. Our results suggest that sequential chemo-radiotherapy achieved encouraging CR rates with no significant increase in toxicity, prolonged survival in non-resectable patients, and enabled organ preservation in patients with resectable disease.

Adult↗
PubMed1996

[Hypertrophic myocardiopathy with isoelectric T waves].

INTRODUCTION AND OBJECTIVES: The lack of specificity of electrocardiographic (ECG) recording showing isoelectric T-waves often leads to diagnostic doubts. This study attempts to demonstrate that asymptomatic patients who demonstrate benign forms of hypertrophic cardiomyopathy may be identified from a typical ECG pattern showing isoelectric T-waves. METHODS: In 45 out of 5,126 asymptomatic healthy aircrew members, an ECG pattern which showed isoelectric T-waves in all leads, but were normal in V2 and V3, was found. 12 of them had negative T-waves in III and aVF leads. Cardiac echo-Doppler, Bruce test and 24-hour Holter recordings were performed in 29 of the 45 cases; all were males aged 30-55 (43.1 +/- 7.1) without any associated disorder nor engaged in heavy exercise, and a control group of 15 healthy subjects. In each of the 29 cases, 2-21 ECG's (11.1 +/- 6.3) performed over a period of 2 to 20 years (13.0 +/- 5.9) were reviewed. RESULTS: In 23 of the 29 cases (79.3%), echo-Doppler criteria of non obstructive mild hypertrophic cardiomyopathy were found. T-waves became normal during exercise testing, returning to isoelectric during recovery, in 19 of the 23 cases. In 17 of these cases, reversible T-wave changes were observed between successive ECG's; T-wave changes became clearly negative when the level of exercise was increased. Holter recordings did not show pathological findings. CONCLUSIONS: We believe that echo-Doppler studies must be performed in asymptomatic patients showing the ECG pattern described above, because they are strongly suspicious of having mild hypertrophic cardiomyopathy.

Adult↗
PubMed1996

Neoadjuvant chemotherapy with continuous infusion of cisplatin and 5-fluorouracil, with or without leucovorin, for locally advanced nasopharyngeal carcinoma.

Cisplatin-based induction chemotherapy has been extensively tested in nasopharyngeal carcinoma for the improvement of local and systemic control and survival of this disease. In this study, we report the results of the treatment with induction chemotherapy in 40 patients with locally advanced carcinoma of the nasopharynx (LANPC) with four courses of cisplatin (P) 25 mg/m2 per day and 5-fluorouracil (F) 1000 mg/m2 per day both in a 4-days continuous infusion, with or without leucovorin (L) 250 mg/m2 per day in 2-hour infusion at the beginning of daily administration of PF, followed by sequential radiotherapy. All except one were in stage IV. The overall response after induction chemotherapy was 93%, with 55% CR and 38% PR. Definitive overall response after radiotherapy was 98%, with 80% CR and 18% PR. At a maximum follow up of 11 years, the overall survival rate is 55%. Induction chemotherapy with continuous infusion of PF with or without leucovorin followed by radiotherapy is a highly active regimen for the treatment of locally advanced nasopharyngeal carcinoma with response and survival rates comparable to other combinations of sequential or simultaneous chemotherapy and radiotherapy.

Adult↗
PubMed1992

Effect of angiotensin II-induced changes in perfusion flow rate on chlorothiazide transport in the isolated perfused rat kidney.

Angiotensin II was used as a probe to study the effect of changes in perfusate flow rate on the renal clearance parameters of chlorothiazide in the isolated perfused rat kidney. Perfusion studies were performed in five rats with no angiotensin II present in the perfusate and in five rats with a 1-4 ng/min infusion of angiotensin II into the perfusate. Angiotensin II had a dramatic effect on the renal hemodynamics, resulting in a 43% decrease in perfusate flow, a 16% decrease in glomerular filtration rate (GFR), and a 45% increase in filtration fraction. Values for the fractional excretion of glucose were low and consistent, with or without angiotensin II. Although the unbound fraction (fu) of chlorothiazide was unchanged between treatments, the renal (CLr) and the secretion clearances were reduced by about 50% in the presence of angiotensin II; the excretion ratio [ER = CLr/(fu.GFR)] was reduced by 38% with angiotensin II present in the perfusate. Analysis of the data was complicated by the presence of a capacity-limited transport for renal tubular secretion. Transport parameters (+/- SD) were obtained and the corrected intrinsic secretory clearance [(Vmax/GFR)/Km] of chlorothiazide was 123 +/- 18 without angiotensin II vs. 72.8 +/- 30.0 with angiotensin II. These results demonstrate that alterations in organ perfusion can significantly reduce the clearance parameters of chlorothiazide in the rat IPK. These flow-induced changes in intrinsic secretory transport may reflect perturbations other than that of perfusion flow rate alone.

Angiotensin II↗
PubMed1992

Influence of angiotensin II-induced alterations in renal flow on excretion of cefonicid in isolated perfused rat kidneys.

The effects of variations in renal perfusate flow on the excretion of cefonicid was examined in isolated perfused rat kidneys. Cefonicid, an expanded-spectrum cephalosporin, is primarily eliminated by active tubular secretion and is neither metabolized nor reabsorbed in the isolated kidney. We used angiotensin II (AII), a strong vasoconstrictor hormone of the afferent and the efferent arterioles in the kidney, to determine whether the renal and secretion clearances, as well as the excretion ratio (ER = CLR/[fu x GFR], where CLR is renal clearance, fu is the unbound fraction, and GFR is glomerular filtration rate), of this low-extraction compound can be altered by a decreased perfusion flow. Control studies were performed in the absence (n = 5) and presence (n = 4) of AII; cefonicid studies were performed in the absence (n = 4) and presence (n = 5) of AII. AII (1 to 4 ng/min) and cefonicid (5 to 10 micrograms/min) were infused into the perfusate. Cefonicid was assayed by high-performance liquid chromatography, and its protein binding was determined by ultrafiltration. AII decreased the perfusate flow rate and increased the renal vascular resistance and filtration fraction of the isolated kidney in the presence and absence of cefonicid. The glomerular filtration rate remained unchanged among the groups. The fractional excretion of glucose was low and steady, indicating a well-preserved tubular function. Although the unbound fraction was unchanged between treatments, the renal and secretion clearances and the excretion ratio of cefonicid were reduced by about 40% in the presence of AII (excretion ratios, 10.3 without AII versus 6.03 with AII). These results suggest that the altered clearance parameters of cefonicid are the result of a flow-induced change in the intrinsic secretory transport of the drug.

Angiotensin II↗
PubMedDate not supplied

Rumen effective degradability of amino acids from soybean meal corrected for microbial contamination.

Rumen degradation kinetics and effective degradability of individual amino acids, total analysed amino acids (TAA) and crude protein (CP) of soybean meal were measured on four rumen-cannulated wethers using the nylon bag technique. Microbial contamination of the incubated residues was corrected using a continuous 15N intraruminal infusion and isolated solid associated bacteria as a reference sample. TAA showed a lower soluble fraction (14.9 vs. 20.8%; P < 0.01), a similar insoluble-degradable fraction (79.0 vs. 79.2%) and a higher degradation rate (11.5 vs. 8.4% x h(-1); P < 0.05) than CP. As a consequence, effective degradability was similar for TAA and CP (74.7 vs. 75.7%). Degradability values of individual amino acids varied moderately (range: +/-6% of TAA degradability). Valine, isoleucine, leucine, alanine, aspartic acid and tyrosine showed significantly lower degradability than TAA, while the opposite effect was observed for histidine, threonine and glutamic acid. Degradability of individual amino acids was related to their soluble fraction (r = 0.877; P<0.001).

Amino Acids↗
PubMedDate not supplied

Effects of stage of harvest on the protein value of fresh lucerne for ruminants.

The ruminal degradation of dry matter (DM) and crude protein (CP) and the intestinal availability of CP of four fresh lucerne (Medicago sativa L.) samples, corresponding to a 3rd growing cycle and harvested at 2-week intervals, were determined. Rumen degradability, measured by the nylon bag technique, and rumen outflow rates were determined on three rumen-cannulated wethers. Intestinal digestibility was determined by the mobile bag technique on three duodenal fistulated wethers. Both groups of animals were fed a 2:1 lucerne hay to concentrate diet at an intake level of 40 g DM x kg(-1) BW0.75. The effective degradability (ED) of DM decreased with maturity in linear and quadratic form, as a consequence of a decrease in the soluble fraction and a similar increase in the undegradable materials. The resultant values were 0.795, 0.661, 0.600, and 0.576 for harvests at 2, 4, 6, and 8 weeks. The ED of CP showed the same trend. However, the variations (values of 0.896, 0.832, 0.791, and 0.817, respectively), were moderate and mainly due to the reduction of the proportion of soluble CP. The intestinal digestibility of CP of all samples showed a downward trend with the increase in the ruminal incubation time, as modelled according to a logistic function. The undegraded CP digested in the gut (Di) and therefore the effective intestinal digestibility (EID) were derived from this function according to the rumen outflow of undegraded CP. The effects of maturity on the mean values of Di, expressed as a proportion of the original CP content, were the opposite of those recorded for the ED of CP. These values were 0.067, 0.102, 0.115, and 0.089 for samples harvested at 2, 4, 6, and 8 weeks, respectively. Nevertheless, when Di was expressed as g CP x kg(-1) DM, these values (18.0, 17.4, 17.1, and 14.3, respectively) decreased in linear form. The same trend was observed for EID values, which represent 0.641, 0.609, 0.549, and 0.488, respectively. The change of the digestion site produced by the reduction of ED of CP was also associated with an increase in the undigested CP (values of 0.037, 0.066, 0.094, and 0.094, at the four harvesting times).

Animal Feed↗
PubMedDate not supplied

[Work conditions of patients with controlled epileptic crises].

OBJECTIVES: To study the employment conditions in a group of patient epileptic adults with control of its seizures, assisted in the University Hospital of Cajuru. PATIENTS AND METHODS: We studied 70 patients that we applied the specific protocol, obtaining data of its origin, profession and job situation. RESULTS: We examined 46 men and 24 women, with mean age 34 years old, where 63 of urban origin and 7 rural. All the patients were in treatment with antiepileptic drugs and without seizures or less than three seizures in the last twelve months. The largest group of patients (35) they met unemployed: 14 retired, 11 of the motivated by the disease, 10 worked as autonomous, 3 only studied and 3 were public employees.

Adolescent↗
PubMedDate not supplied

[Interferon-alpha2b recombinant improved the cognitive dysfunction in patients with relapsing remitting multiple sclerosis].

INTRODUCTION: Some experimental, Phase II clinical trials and the preliminary reports of the Cuban Phase III clinical trial indicate that alpha-IFN (IFN) may be useful in relapsing remitting (RR) multiple sclerosis (MS). The reports in Cuba showed that 70% of the MS patients have cognitive dysfunction. OBJECTIVE: To assess the efficacy of IFN-alpha2b recombinant in the cognitive dysfunction of RR MS. PATIENTS AND METHODS: 57 RR-MS clinical definite patients from the randomised, double blind, placebo controlled study of 225 patients with RR-MS and brain MRI confirmed. Patients were randomly assigned to receive intramuscular IFN-alpha2b (Heberon R) 10 million IU (high dose), 3 million IU (low dose) or placebo twice week for 2 years. Outcome results were blinding evaluated considering changes in the following tests: Luria, WAIS, Benton and PASAT-3. Adverse events and side effects were not evaluated to maintain physician blinding. RESULTS: The initial comparison of the groups did not show any differences among the placebo (n=20), low dose (n=18) and high dose (n=19) considering age (p=0.234), gender, ethnic group (p=0.012), years ill (p=0.787), EDSS (p=0.203) and rate of relapses (p=0.432). The Luria's Test showed an improved in the low dose group from 2.50 +/- 1.34 to 1.39 +/- 1.85 (p=0.029) and in the high dose group from 3.22 +/- 1.89 to 2.17 +/- 1.50 (p=0.006) vs placebo 2.85 +/- 1.66 to 2.90 +/- 1.97 (p=0.723). The results of the Benton's test demonstrated that the low dose group had an improved from 5.50 +/- 1.10 to 6.22 +/- 1.31 (p=0.047), in the high dose group from 4.87 +/- 1.85 to 5.78 +/- 1.35 (p=0.005) where as in the placebo group worse from 5.15 +/- 1.76 to 5.05 +/- 2.11 (p=0.893). The WAIS test showed the same results, the low dose group increased from 5.17 +/- 1.34 to 6.06 +/- 1.21 (p=0.022), the high dose group from 4.56 +/- 1.38 to 5.39 +/- 1.29 (p=0.007) and the placebo group worse from 5.25 +/- 1.25 to 5.05 +/- 1.57 (p=0.354). Finally, the PASAT-3 test increased in the IFNs groups: from 45.72 +/- 10.61 to 49.94 +/- 11.68 (p=0.015) in the low dose group, from 42.67 +/- 11.04 to 48.72 +/- 8.84 (p=0.03) in the high dose group, but in the placebo group worse from 44.55 +/- 10.86 to 41.95 +/- 13.74 (p=0.655). CONCLUSION: IFN-alpha improved the cognitive dysfunction in RR-MS patients. The higher dose is more beneficial.

Adult↗