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Biomedical subjects

R Rodríguez

Publications and source records attributed to R Rodríguez.

At least 199 records · Page 11Linked to original sources
PubMed1993

Mitotic index and cell proliferation kinetics for identification of antineoplastic activity.

The mitotic index (MI) and cell proliferation kinetics (CPK) of human blood lymphocyte cultures were determined to evaluate the effects of six antineoplastic drugs with well known cytostatic activity: cisplatin, melphalan, bleomycin, methotrexate, 5-fluorouracil and 6-mercaptopurine. All six drugs showed a clear effect on the inhibition of MI. The first three drugs interact directly with DNA showing a dose-related retardation of CPK. Methotrexate, 5-fluorouracil and 6-mercaptopurine, which act on ribonucleotide biosynthesis, showed no significant effects on CPK. The results suggest that CPK and MI measurements are useful for the prescreening of drugs with potential cytostatic activity.

Adult↗
PubMed1993

Fate of oral enzymes in pancreatic insufficiency.

Oral pancreatic enzyme supplements, including those protected from gastric acidity by enteric coating, often achieve only partial correction of pancreatic steatorrhoea. To characterise the mechanisms involved in vivo, eight patients with steatorrhoea due to advanced pancreatic insufficiency and nine healthy controls were studied. Two sets of studies (small bowel intubation and five day faecal fat quantification) were randomly performed while patients were either on enteric coated pancreatin or equivalent placebo. A 260 cm long multilumen tube was used for double marker perfusion of two 20 cm segments located in the duodenum and in the ileum respectively. Luminal pH, flow, and trypsin and lipase activity outputs were measured at each segment for four hours postcibally. Placebo treated patients with pancreatic steatorrhoea had low enzyme outputs in the duodenal test segment and even lower outputs in the ileal segment. Pancreatin treatment significantly decreased steatorrhoea (p < 0.05) and increased luminal enzyme outputs (p < 0.05). The increase was much greater in the ileal than in the duodenal segment. Thus enteric coated pancreatin treatment abolished the normal gradient between postcibal duodenal and ileal lipase output. The results suggest that enteric coated pancreatin nearly corrects severe pancreatic steatorrhoea. The ingested lipase was utilised inefficiently, however, as luminal enzyme activity in the ileum was enhanced to a greater extent than in the duodenum, and consequently the absorptive potential of the small bowel was only partially utilised.

Celiac Disease↗
PubMed1993

[Geographic distribution of mortality from cancer of the stomach and the colon in Spain].

The present study analyzes the mortality of gastric and colon cancer in Spain from 1975 to 1985, and examines the figures obtained for each Spanish province as well as in several major cities. During the study period, proportional mortality for all cancers increased, except for gastric cancer which decreased both for men and women. We found that Soria the highest mean mortality rate due to gastric cancer (81.83), whereas figures were highest for men in Segovia (97.71) and for women in Soria (66.69). By contrast, Gran Canaria had the lowest mean mortality rate due to gastric cancer (6.26), whereas lowest values were obtained for men in Tenerife (8.42) and for women in Gran Canaria (4.11). On the other hand, the highest mortality rate due to colon cancer was found in Gerona (19.11), and the sex distribution was as follows: for men the rate was highest in Gerona (22.22), and for women in Burgos (19.75). Albacete had the lowest mortality rate due to colon cancer (1.09); for men the lowest was obtained in Avila (1.20), and for women in Albacete (0.90). This geographical distribution suggest that environmental as well as dietary factors may play a role in cancer mortality.

Adult↗
PubMed1993

[The verbal autopsy on children with a respiratory infection and acute diarrhea. An analysis of the disease-care-death process].

The study focuses on children between 72 hours and five years of age who died of acute respiratory infection (ARI) or acute diarrhea (AD) in the State of Tlaxcala. Peer Review Mortality Committee of the State contributed with the staff to the deaths analysis. Cases were included only when diagnosis was confirmed by verbal autopsy (VA). One hundred and thirty two cases were included (98 corresponding to ARI deaths and 34 to AD). The process related to medical care-seeking behaviors and prescribing practices by private and non-private physicians was analyzed through the VA. During the study period, 60% of children with ARI and 58.9% of children with AD died at home. More than 80% of these children had received medical care within three days preceding their death, and 50% of them had been seen by a physician within 12 hours prior to their death. Most of these visits were to a private doctor (71% for ARI and 86% for AD). Forty seven percent of treatments prescribed for ARI were judged to be wrong, either because of a bad choice of antibiotic or because the physician did not prescribe an antibiotic when the patient required it. Similarly, 65% of treatments for AD were considered erroneous, either due to the use of an antibiotic which was not justified or due to the lack of oral rehydration therapy when it was needed. Additionally, late referral to a hospital was considered as having direct influence at the death in half of the consultation. Families were too late in demanding medical care or demanded no care at all in 21.9% of cases of ARI and in 6.1% of cases of AD. We have found the VA to be useful in identifying problems related to the process of health-seeking behaviors and medical care. Our results suggest interventions that may lower the high mortality rates in Tlaxcala, such as training workshops directed to institutional and private physicians, and the implementation of top-of-line treatment centers where high-risk patients can be referred and also the health care workers can learn the correct treatment of both diseases. Future studies should focus on the identification of alarm signs and risk factors that may help to lower mortality due to ARI or AD, when recognized and treated at early stages.

Acute Disease↗
PubMed1993

Genetic evidence of a species complex in Anopheles pseudopunctipennis sensu lato.

This preliminary report provides information concerning genetic variation in the vector mosquito Anopheles pseudopunctipennis sensu lato that could have malaria control implications. Because of inconsistencies in malaria transmission patterns within geographic zones inhabited by this vector, the possibility that it represents a species complex was investigated. Hybrid crossing studies, electrophoretic analysis of enzyme variation, and DNA restriction studies were carried out in mosquitoes captured in nine areas of Mexico, Bolivia, and Peru. The findings demonstrated the existence of a species complex believed to have resulted from allopatric speciation. This research points to a need for establishing the geographic distribution of the newly recognized species because of their potential influence on malaria control.

Animals↗
PubMed1992

Tumor cytostasis mediated by a monoclonal IgM antibody promoting adhesion between macrophages and tumor cells. Evidence for a lectin-like behavior.

We have shown previously that an IgM mAb (A10) recognizing Ehrlich tumor (ET) cell surface carbohydrates, inhibits in vivo ET growth by a macrophage-dependent mechanism. The inhibition mechanism involving both IgM and macrophages was unclear because receptors for IgM on macrophages are controversial and another monoclonal IgM (E1), also recognizing ET cell surface carbohydrates, was completely unable to show any protective effect. Here we show that A10, but not E1, was able to promote adhesion between macrophages and ET cells by a receptor for IgM-independent mechanism. Immunofluorescence studies showed that A10, but not E1, did react with macrophages if these cells were preincubated with a source of Ag spontaneously released from ET cells. This Ag release appeared to be required for A10-mediated adhesion, because adhesion was not obtained when ET cells fixed with paraformaldehyde were used. Cytostasis studies performed with macrophages stimulated with L-929 conditioned medium and ET cells showed that A10, but not E1 nor unrelated IgM, was able to inhibit ET cell proliferation in vitro by a mechanism involving cell contact between both cell populations. Therefore, IgM inhibition of ET growth, both in vivo and in vitro, could be explained by a lectin-like mechanism, where IgM, recognizing Ag of tumor origin, bridges macrophages to tumor cells.

Animals↗
PubMed1992

Nitrate transport in the cyanobacterium Anacystis nidulans R2. Kinetic and energetic aspects.

Nitrate transport has been studied in the cyanobacterium Anacystis nidulans R2 by monitoring intracellular nitrate accumulation in intact cells of the mutant strain FM6, which lacks nitrate reductase activity and is therefore unable to reduce the transported nitrate. Kinetic analysis of nitrate transport as a function of external nitrate concentration revealed apparent substrate inhibition, with a peak velocity at 20-25 microM-nitrate. A Ks (NO3-) of 1 microM was calculated. Nitrate transport exhibited a stringent requirement for Na+. Neither Li+ nor K+ could substitute for Na+. Monensin depressed nitrate transport in a concentration-dependent manner, inhibition being more than 60% at 2 microM, indicating that the Na(+)-dependence of active nitrate transport relies on the maintenance of a Na+ electrochemical gradient. The operation of an Na+/NO3- symport system is suggested. Nitrite behaved as an effective competitive inhibitor of nitrate transport, with a Ki (NO2-) of 3 microM. The time course of nitrite inhibition of nitrate transport was consistent with competitive inhibition by mixed alternative substrates. Nitrate and nitrite might be transported by the same carrier.

Biological Transport↗
PubMed1992

[A 2-year follow-up of a program for the control of cardiovascular risk factors among asymptomatic workers].

In 1987, a cardiovascular risk profile was obtained on 836 workers of the National Electricity Co in Santiago. There were 714 males and 125 females, the mean age was 45 years (ES +/- 0.3). Hypertension (systolic pressure > 160 or diastolic > 90 mmHg) was present in 17% of subjects, hypercholesterolemia (> 240 mg/dl or > 220 mg/dl associated to 2 other risk factors) in 17%, obesity (> 20% above ideal weight) in 33% and 29% were smokers. An advice to stop smoking, changes in the casino menu and hypertension, obesity and hypercholesterolemia's control programs were offered. These were attended by 108 hypertensives, 141 subjects with hypercholesterolemia and 104 obese individuals with an attendance rate of 64%, 75 and 77% respectively. Measurements repeated 2 years later revealed a reduction in diastolic pressure of 3.3 +/- 1.1 mmHg (p < 0.004) only in adherent subjects. Cholesterol levels were reduced by 24 +/- 3 mg/dl (p < 0.001) with no differences for non participants, adherent and non adherent subjects. Adherent obese subjects reduced their weight by 2.2 +/- 0.4 kg (p < 0.001). There was no change in the number of smokers.

Cardiovascular Diseases↗
PubMed1992

[Genetic evidence of a species complex in Anopheles pseudopunctipennis pseudopunctipennis].

In light of inconsistencies in the pattern of malaria transmission within geographical areas inhabited by Anopheles pseudopunctipennis pseudopunctipennis, a study was carried out to investigate the possibility that this vector constitutes a species complex. Hybrid crossing studies, electrophoretic analysis of enzyme loci, and DNA restriction analysis were conducted on mosquitoes captured at nine sites in Mexico, Bolivia, and Peru. The sterility of generations resulting from cross-mating of Mexican female mosquitoes and South American male mosquitoes; the results of electrophoretic analysis, which showed differences at two loci; and a genetic distance value of 0.13 confirmed the existence of a species complex, probably produced by allopatric speciation. It is concluded that the geographic distribution of this newly discovered species complex should be defined, in view of its potential effect on malaria control.

Animals↗
PubMed1991

A new distinct group of 2 S albumins from rapeseed. Amino acid sequence of two low molecular weight napins.

Two napins (nIa and nIb), isolated from Brassica napus (rapeseed) seeds, have been sequenced. The two proteins show the common structural pattern of the 2 S albumins, since they are composed of two disulfide-linked chains of different size, yet they exhibit an atypical low molecular weight (12.5 kDa vs. 14.5 kDa of the major napins). High sequence similarity has been found between these 2 proteins, but only 54% similarity can be estimated from their comparison with the 14.5 kDa major napins. Thus, nIa and nIb are considered representatives of a new distinct group of rapeseed napins since all the previously known napins exhibit 95% sequence similarity. Unexpectedly, the similarity increases when compared with the 2 S proteins from other species.

2S Albumins, Plant↗
PubMed1991

Structural analysis of the small chain of the 2S albumin, napin nIII, from rapeseed. Chemical and spectroscopic evidence of an intramolecular bond formation.

Napin nIII is a 2S albumin from rapeseed (Brassica napus L.) homologous to the major mustard allergen. It is composed of two different polypeptide chains linked by two disulphide bonds. The small chain has been isolated by reverse-phase HPLC after reduction of the native protein and its primary structure elucidated. This 37 residue polypeptide contains only two cysteines, at positions 10 and 23, which show a great tendency to form a non-native intramolecular disulphide bridge. The kinetic analysis of this process was performed by measuring the fluorescence emission of the single tryptophan residue of the molecule since its fluorescence intensity is about 30% decreased during disulphide formation. Small changes on the secondary structure of the polypeptide were measured by circular dichroism. The process is delayed in the presence of the reduced large chain of nIII. However, no dimer formation was detected under the conditions used, either between small chains or between the small and the large chains. Thus, the interchain disulphide formation in napin nIII should be considered as an early step during maturation of this multi-subunit seed protein.

2S Albumins, Plant↗
PubMed1991

Hand motor patterns after the correction of left-nondominant-hand mirror writing.

In a previous report, the author studied a left-nondominant-hand mirror writer, postulating that her mirror writing resulted from the failure to reverse the right-hand writing motor patterns when transmitted from the left to the right cerebral hemisphere. In this study, the patient was asked to write in normal fashion with the left hand; the result was a mixture of handwriting motor patterns which included normal letters, letters with reversed direction tracings, letters with one or more than one loop-tracings and illegible letters. The author considers this result to be a further support for the above-proposed hypothesis.

Adult↗
PubMed1991

Isolation and characterization of a major allergen from oriental mustard seeds, BrajI.

A 2 S albumin from oriental mustard (Brassica juncea) seeds has been isolated and characterized as an allergen. This protein, BrajI, was recognized by human IgE from mustard-sensitive individuals, as proved by using two different enzyme immunoassays. BrajI was found to be closely related to Sin a I, the major allergen from yellow mustard seeds. Many fractions with molecular weights ranging from 16,000 to 16,400 and with differences in charge were separated by ion-exchange chromatography. They exhibited small but significant amino acid composition differences for Glx, Val, Ile, Lys, and Arg contents. The heterogeneity of BrajI can be explained by size and charge differences of its heavy and light chains. All of the isoallergenic forms of BrajI gave a single precipitation band in double diffusion immunoassays when using a Sin a-I-specific rabbit polyclonal serum.

2S Albumins, Plant↗