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Biomedical subjects

M L Rodriguez

Publications and source records attributed to M L Rodriguez.

At least 37 records · Page 2Linked to original sources

Structure and serological properties of the capsular K11 antigen of Escherichia coli O13:K11:H11.

The capsular K11 antigen of Escherichia coli contains glucose, fructose, and phosphate in the molar ratios 2:1:1, and a backbone of -4)-beta-D-glucopyranosyl-(1----4)-alpha-D-glucopyranosyl phosphate-(1----to which beta-D-fructofuranose is linked at position 3 of the beta-D-glucopyranosyl residue. The fructose, which is the immunodominant sugar of the K11 antigen, is released from the polysaccharide under mild acidic conditions (70 degrees, pH 5.0).

Antigens, Bacterial↗

Cognitive person variables in the delay of gratification of older children at risk.

The components of self-regulation were analyzed, extending the self-imposed delay of gratification paradigm to older children with social adjustment problems. Delay behavior was related to a network of conceptually relevant cognitive person variables, consisting of attention deployment strategies during delay, knowledge of delay rules, and intelligence. A positive relationship was demonstrated between concurrent indexes of intelligence, attention deployment, and actual delay time. Moreover, attention deployment, measured as an individual differences variable during the delay process, had a direct, positive effect on delay behavior. Specifically, as the duration of delay and the frustration of the situation increased, children who spent a higher proportion of the time distracting themselves from the tempting elements of the delay situation were able to delay longer. The effect of attention deployment on delay behavior was significant even when age, intelligence, and delay rule knowledge were controlled. Likewise, delay rule knowledge significantly predicted delay time, even when age, attention deployment, and intelligence were controlled.

Age Factors↗

Structure and serological characteristics of the capsular K4 antigen of Escherichia coli O5:K4:H4, a fructose-containing polysaccharide with a chondroitin backbone.

The chemical structure of the K4-specific capsular polysaccharide (K4 antigen) of Escherichia coli O5:K4:H4 was elucidated by composition, carboxyl reduction periodate oxidation methylation nuclear-magnetic-resonance spectroscopy and enzymatic cleavage. The polysaccharide consists of a backbone with the structure----3)-beta-D-glucuronyl-(1,4)-beta-D-N-acetylgalactosaminyl(1- to which beta-fructofuranose is linked at C-3 of glucuronic acid. Mild acid hydrolysis liberated fructose and converted the K4 antigen into a polysaccharide which has the same structure as chondroitin. The defructosylated polysaccharide was a substrate for hyaluronidase and chondroitinase. The serological reactivity of the K4 polysaccharide was markedly reduced after defructosylation.

Antigens, Bacterial↗

Comparative structural elucidation of the K18, K22, and K100 antigens of Escherichia coli as related ribosyl-ribitol phosphates.

The structures of the capsular K18, K22, and K100 antigens of E. coli O23:K18:H15, O23:K22:H15, and O75:K100:H5, respectively, were elucidated by determination of composition, 1H-, 13C-, and 31P-n.m.r. spectroscopy, periodate oxidation, alkaline hydrolysis followed by incubation with alkaline phosphatase, and methylation analysis of the polymers and their neutral fragmentation products. The polymers are poly(ribosyl-ribitol phosphates) related to the capsular antigen of H. influenzae (Hib). The K22 antigen has the repeating unit -P-2)-beta-Rib-(1----2)-RibOH-(5-, and the K18 antigen has the same polymer chain with partial 3-O-acetylation of the ribose moiety. The K100 antigen consists of repeating units of -P-3)-beta-Rib-(1----2)-RibOH-(5- and seems to have a secondary structure different from that of the other antigens. Together with the Hib capsular antigens, the structure of which was reported as -P-3)-beta-Rib-(1----1)-RibOH-(5-, these capsular antigens represent a structurally related group of capsular polymers.

Carbohydrate Conformation↗

Adjusting delay to reinforcement: comparing choice in pigeons and humans.

Indifference functions of amount and delay of reinforcement were compared for pigeon and human subjects by using Mazur's (1987) adjusting delay procedure. A model similar to the matching law (the simple reciprocal model), a hyperbolic model, three modified versions of the hyperbolic model, and a negative exponential model were evaluated. In Experiment 1 the subjects were pigeons, and in Experiments 2 and 3 the subjects were humans. In order to make the nonhuman and human situations more comparable, in Experiments 2 and 3 the reinforcer (points exchangeable for money) was discounted at a constant rate during the delay periods. The rate of this discounting varied between Experiments 2 and 3. The results of all three experiments demonstrated that a power function transformation of the hyperbolic model (in which 1 is added to the delays in the denominator of the simple reciprocal model) provided the best description of both nonhuman and human data.

Animals↗

Hydrogen bonds between protein side chains and phosphates and their role in biological calcification.

Poly(L-histidine)-phosphate (H2PO4-, HPO4(2-)) and poly(L-glutamate)-phosphate systems (residue/phosphate, 1:1) in the presence of Ca2+ are studied by infrared spectroscopy. In the poly(L-histidine)-phosphate systems N...HOP in equilibrium NH+...O-P hydrogen bonds are formed where most phosphate protons are found at the histidine ring. With an increase in the degree of hydration the proportion of the proton limiting structure NH+...O-P increases. In the poly(L-glutamate)-dihydrogen phosphate system most phosphate protons are found at the carboxylate groups. Different behavior is observed for poly(L-glutamate)-hydrogen phosphate mixtures, where the residence time of the phosphate proton at the hydrogen acceptor carboxylate group is very short. This residence time increases, however, with increasing humidity. All these results support the triphasic theory of biological calcification involving a tripartite protein-calcium-phosphate complex where these hydrogen bonds can be present. The behavior of these hydrogen bonds can also explain the formation of a nidus of calcium phosphate salts in calcium oxalate-containing urinary calculi.

Animals↗

Quantitative assessment of vaginal microflora during use of tampons of various compositions.

Although the effect of vaginal tampons on the microbial flora during menstruation has recently been studied by several investigators, quantitative effects attributable to particular tampon fibers have received less attention. The purposes of the present study were (i) to determine and then to compare the effects of polyacrylate rayon tampons and viscose rayon tampons on the normal vaginal flora, (ii) to compare quantitative bacterial counts obtained from these tampons with those obtained from concomitant vaginal swabs, and (iii) to determine whether either of these tampon types alters the vaginal microflora when compared with the microflora in the same women using all-cotton tampons or external catamenial pads. Tampon and swab samples were obtained at predetermined times from 18 women for an average of seven menstrual cycles. Samples consisting of swabs from women wearing menstrual pads were compared with swab and tampon samples taken at predetermined times during the menstrual cycle from women using cotton, polyacrylate rayon, or viscose rayon tampons. Samples were analyzed for total aerobic, facultative, and anaerobic bacterial counts. Statistical evaluation of the results indicated that, on the whole, total bacterial counts decreased during menstruation and that the numbers of bacteria in tampons tended to be lower than those in swab samples taken at the same time. The tampon type had little effect on the vaginal microflora.

Adult↗

Qualitative assessment of vaginal microflora during use of tampons of various compositions.

The effect of vaginal tampons on the microbial flora during menstruation has recently been studied by several investigators. However, little information regarding the qualitative effects attributable to particular tampon fibers is available. The purpose of the present study was to compare the effects of polyacrylate rayon tampons and cotton-viscose rayon blend tampons on the qualitative bacterial counts obtained from tampons and concomitant vaginal swabs and to determine whether either of these tampon types alters the qualitative makeup of the vaginal microflora when compared with the microflora in the same women using all-cotton tampons or external catamenial pads. Tampon and swab samples were obtained as described previously (A. B. Onderdonk, G. R. Zamarchi, M. L. Rodriguez, M. L. Hirsch, A. Muñoz, and E. H. Kass, Appl. Environ. Microbiol. 53:2774-2778). The genus and species of the six dominant bacterial species in each sample were identified, if possible. A statistical evaluation of the qualitative makeup of the microflora revealed that the same numerically dominant phenotypes were present regardless of sample type, sample time, or catamenial product. Predictable changes in total numbers among the dominant species were also noted when the data were evaluated by day of menstrual cycle. The correlation between the total numbers of each dominant species present was evaluated by day of cycle, and the findings are discussed.

Adult↗

Self-control in adult humans: variation in positive reinforcer amount and delay.

In five experiments, choice responding of female human adults was examined, as a function of variations in reinforcer amount and reinforcer delay. Experiment 1 used a discrete-trials procedure, and Experiments 2, 3, 4, and 5 used a concurrent variable-interval variable-interval schedule. Reinforcer amount and reinforcer delay were varied both separately and together. In contrast to results previously reported with pigeons, the subjects in the present experiments usually chose the larger reinforcers even when those reinforcers were delayed. Together, the results from all the experiments suggest that the subjects followed a maximization strategy in choosing reinforcers. Such behavior makes it easy to observe self-control and difficult to observe impulsiveness in traditional laboratory experiments that use adult human subjects.

Adolescent↗

Choice in a self-control paradigm: Quantification of experience-based differences.

Previous quantitative models of choice in a self-control paradigm (choice between a larger, more-delayed reinforcer and a smaller, less-delayed reinforcer) have not described individual differences. Two experiments are reported that provide additional quantitative data on experience-based differences in choice between reinforcers of varying sizes and delays. In Experiment 1, seven pigeons in a self-control paradigm were exposed to a fading procedure that increased choices of the larger, more-delayed reinforcer through gradually decreasing the delay to the smaller of two equally delayed reinforcers. Three control subjects, exposed to each of the small-reinforcer delays to which the experimental subjects were exposed, but for fewer sessions, demonstrated that lengthy exposure to each of the conditions in the fading procedure may be necessary in order for the increase to occur. In Experiment 2, pigeons with and without fading-procedure exposure chose between reinforcers of varying sizes and delays scheduled according to a concurrent variable-interval variable-interval schedule. In both experiments, pigeons with fading-procedure exposure were more sensitive to variations in reinforcer size than reinforcer delay when compared with pigeons without this exposure. The data were described by the generalized matching law when the relative size of its exponents, representing subjects' relative sensitivity to reinforcer size and delay, were grouped according to subjects' experience.

Journal Article↗

Antenatal diagnosis of mosaic trisomy 8 confirmed in fetal tissues.

An aneuploid karyotype with an extra submetacentric C-group chromosome was observed in all metaphase cells in 5 of 24 primary amniotic fluid cell clones and in admixture with normal cells in two additional clones. Trisomy 8 was demonstrated by R-banding. The parents elected to terminate the pregnancy. Successful cultures were initiated from nine fetal tissues and aneuploid cells were observed in cultures derived from two separate sites in the skin.

Adult↗

Levamisole therapy for multiple warts.

Levamisole, a wide-spectrum antiparasitic drug, increases cellular immunity in vivo and in vitro. Patients with verruca vulgaris may have defective cell mediated immune mechanisms. Levamisole was given to twenty-two patients with multiple warts, 5 mg/kg body weight on 3 consecutive days every fortnight. Patients' lymphocytes were studied for E-rosette formation before therapy. E-rosette counts were lower in patients compared with controls and a significant increase was obtained after in vitro incubation with levamisole. Seventeen patients were cured in 1-4 months, there were four failures and one patient showed marked improvement. It is concluded that patients with multiple warts have defective cell-mediated mechanisms as far as the E-rosette count is concerned and that levamisole increases in vitro E-rosette formation and is useful in the treatment of these patients.

Adolescent↗

Mosaicism in amniotic fluid cell cultures: classification and significance.

The last decade has witnessed increasing application of human cytogenetic technology to prenatal chromosome analysis. However, unlike the rather uniform peripheral blood T-lymphocyte system which has provided most of our experience in human cytogenetics, long-term amniotic-fluid cell cultures display extreme cellular heterogeneity and disproportionate growth of certain cell types as a consequence of clonal amplification. When they enter cell culture, many of these cells are approaching the terminal stages of their respective, life spans and may have accumulated chromosomal aberrations. Concern about the possibility of true fetal mosaicism seems warranted chiefly in situations were multiple colonies display potentially viable aberrations. Clonal analysis, preferably of multiple clonal types, and attention to details of clonal morphology are likely to minimize diagnostic errors and undue apprehension resulting from mosaicism in amniotic-fluid cell cultures.

Amniocentesis↗

Amniotic fluid cell mosaicism for presumptive trisomy 20.

Trisomy for an F-like chromosome with banding characteristics of chromosome 20 was observed, respectively, in 25 and 8% of amniotic fluid cell clones in two cases of prenatal diagnosis for advanced maternal age. No such aneuploidy was found upon examination of fetal or postnatal tissues. In both instances there were no detectable malformation. It is suggested that propensity to nondisjunction for an F-like chromosome, not unlike tetraploidy, might be another characteristic of amniotic fluid cells in culture.

Abortion, Induced↗

Creative teams: an experiential activity.

BACKGROUND: Staff development educators in a Department of Education & Development were seeking a creative activity to reinforce the qualities of effective teams. METHOD: Staff development educators developed an experiential activity that provides an opportunity to observe team behaviors by introducing several glitches into a goal-oriented team project. Later, observed team behaviors were explored with the group. RESULTS: The activity allowed participants to practice collaboration, communication, and problem-solving skills while functioning as a team. CONCLUSION: This activity, which is easily adaptable to any audience, creatively integrates the principles of adult learning to provide participants with an opportunity to discuss and practice behaviors necessary for teamwork in the current health care settings.

Adult↗