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V Zúñiga

Publications and source records attributed to V Zúñiga.

15 recordsLinked to original sources
PubMed2006

Reactions, characterization and uptake of ammoxidized kraft lignin labeled with 15N.

Ammoxidation of kraft lignin was carried out in a Parr reactor using (15)NH(3) as the main nitrogen source. Reaction parameters were set up until a total nitrogen content of approximately 13 wt.% in lignin was achieved, in accordance with conditions of previous studies. Analytical tools such as FTIR, Py-GC/MS, and solid state NMR were used in this research. The nature of nitrogen bondings is discussed. The incorporation of the (15)N from ammoxidized lignin was followed in pumpkins (Zucchini cucurbita pepo L.) by means of (15)N emission spectroscopy.

Ammonia↗
PubMed2001

Biomechanical and biochemical pulping of sugarcane bagasse with Ceriporiopsis subvermispora fungal and xylanase pretreatments.

Sugarcane bagasse was pretreated with both the white-rot fungus, Ceriporiopsis subvermispora, and xylanase enzyme for 2 weeks before soda chemithermomechanical (CTMP) and soda chemical (CP) cooking. For fungi-CTMP (BCTMP) and enzyme-fungi-CTMP (EBCTMP), the bagasse, after bio-pretreatment, was cooked with 5% sodium hydroxide, at 130 degrees C for 20 min. For the chemical pulping (CP), after fungi pretreatment (BCP) or after xylanase and fungal pretreatment (EBCP), the bagasse was cooked with 14.5% sodium hydroxide. With the BCTMP, the Klason lignin was reduced, all of the pulp strength properties were increased, and a 28% savings in refining energy consumption was obtained, but the brightness was reduced 5 points compared to the control. With the EBCTMP, the brightness losses were overcome but with a mild reduction in the pulp strength properties compared to the BCTMP. The energy savings were 5% greater than from BCTMP and 33% over the control. The BCP treatment increases somewhat the pulp strength properties, reduces the energy consumption 23%, and reduces the brightness by 9 points compared to the control; however, the kappa no. was 5.5 points higher than the control. EBCP treatment reduces brightness losses and increases the pulp yield 2% compared to the control, but with some reduction in the strength properties compared to BCP.

Basidiomycota↗
PubMed1989

[Resistance of enterobacteria and Pseudomonas to old and new antimicrobial agents].

Antibiotic sensitivity to eight common use antibiotics for 9,538 enterobacteria and Pseudomonas strains isolated from hospitalized children was studied using the serial dilution plate technique. Minimum inhibitory concentration to seven new antibiotics for 310 strains was also determined. Enterobacteria showed high resistance (50-80%) to ampicillin, carbenicillin, sulbenicillin, chloramphenicol and trimethoprim/sulfamethoxazole; resistance to piperacillin, gentamicin, tobramycin, and netilmicin was moderate (15-45%), and resistance to amikacin, cefotaxime, moxalactam and aztreonam was low (2-10%). Pseudomonas strains showed less than 20% resistance to carbenicillin, piperacillin, amikacin and aztreonam. Enterobacteria isolated from urine samples showed low resistance to nitrofurantoin and nalidixic acid (15%). Therapeutic recommendation for most frequent infections caused by these etiologic agents based on the resistance values found were elaborated.

Anti-Bacterial Agents↗
PubMed1989

[Infections by anaerobes in children: frequency of isolation and antimicrobial resistance].

We studied the frequency of isolation and antimicrobial susceptibility of strict anaerobic bacteria isolated in a paediatric hospital. A total of 1,753 samples from purulent material and hemocultures were processed. One hundred and thirty strains were isolated from 95 children: 44 from 48 cases of peritonitis (91.7%), 2 from 8 brain abscesses (25%), 23 from 124 soft tissue abscesses (18.5%), 4 from 64 empyemas or lung abscesses (6.3%) and 22 from 1,509 hemocultures (1.5%). Mixed infection (anaerobic and aerobic bacteria) was detected in 38.5% of the cases; however, in peritonitis 81.3% of the cases showed mixed infection. The more frequently isolated bacteria were: Bacteroides (44.6%), Clostridium (19.2%), Fusobacterium (7.7%) and gram positive cocci (7.7%). Propionibacterium acnes was isolated in 15 specimens; however, most of them were considered as contamination. Bacteroides was isolated more frequently from patients with peritonitis (51.6%). The susceptibility to five antibiotics was tested in 124 strains using the method of serial dilutions in agar plates. The genus Bacteroides showed a high resistance to penicillin (73.1%), moderate to clindamycin (11.5%) and low to cefoxitin, chloramphenicol and metronidazole (6.8%, 2% and 5.8%). The rest of the anaerobic strains tested (other gram negatives and grampositives) were highly sensitive to all the antimicrobials tested, except for clindamycin (26.7% and 36.9% resistance, respectively). Cefoxitin, chloramphenicol and metronidazole had the lower CMI50 and CMI90 for the genus Bacteroides; and for the rest of the bacteria, penicillin had the highest activity (CMI90 less than 0.025). Since the frequency of isolation of anaerobic bacteria in children with severe infections, presumably originated from the digestive tract, paranasal sinus and middle ear is high, anaerobic cultures must be practiced in these patients. Empiric antimicrobial treatment should also be started. This treatment should be with penicillin when the probability of isolation of Bacteroides is low (infections in the face, neck, thorax and soft tissues) and with metronidazole in intraabdominal infections. Because of the severity and probable etiology of brain abscesses, treatment with penicillin and chloramphenicol or metronidazole is recommended in these cases.

Anti-Bacterial Agents↗
PubMedDate not supplied

[Treatment with human colostrum of children with prolonged infectious gastroenteritis].

The results of treatment with human colostrum in 6 babies with protracted infectious diarrhea from enteropathogenic E. coli and/or Salmonella are reported. Active diarrhea was present in 5 cases and the 6th was a carrier. Remission was obtained in cases with diarrhea and all showed increase in weight. Negativeness of stool cultures was achieved in four cases and in the other two, the bacteriologic control was not complete. One patient died from a secondary pulmonary infectious problem. As an average, all patients showed rise in secretory IgA and in IgG measured at the duodenal fluid level and in comparison with a control group, there were statistically significant differences. Serum immunoglobulins showed no changes following administration of human colostrum. Although the number of patients reported is small, the results obtained may be considered favorable.

Administration, Oral↗
PubMedDate not supplied

[Microbiology of chronic otitis media in children and comparison of 2 technics for obtaining otic secretions].

Samples of otic secretion for culture were taken to 50 children with suppurative chronic otitis media; two techniques were followed: with a cotton swab from the external meatus or with a sterile metal aspirator, through the tympanic perforation under microscopic control. To 20 of them with unilateral chronic otitis media, a swab with product from the external meatus of the healthy ear was also taken; in 65% of the latter, the same germs were found in both ears, but when the sample was taken with the aspirator, only in 15% were the germs the same (p less than 0.01). Two or more germs were isolated in 54% of the ears following the technique of the swab and in 32% with the aspiration. The predominant microorganisms with the swab technique were gram-positive cocci (S. epidermidis 48% S. aureus 16%); while the aspiration technique reported gram-negative germs in 96% of cultures (Proteus sp. 42%, Pseudomonas sp. 30% and S. aureus only in 14%). We believe that the sample obtained with a swab has a high degree of contamination with the normal flora of the external meatus; therefore, it should be relinquished.

Adolescent↗
PubMedDate not supplied

[Immunopathology of nephropathy secondary to anaphylactoid purpura].

With the purpose of contributing to the study of the pathogenesis of the nephropathy of anaphylactoid purpura (NPA), investigation was made of the presence and extension of immunoglobuline deposits, complement factors and fibrinogen in renal biopsies of 15 patients with NPA, correlating the findings with glomerular lesions seen at the light microscope. Fibrin and IgA deposits were found in all biopsies in mesangium, while C3 was detected only in 5 cases with potentially progressive lesions: 3 with PEEF, one with PEED and one with MP, being negative in PSF and PE cases, which are potentially reversible. The extension of deposits was diffuse or segmentary, without the existence of a precise correlation with the different morphological types. It is concluded that the immunopathologic pattern found in NPA is quite characteristics, different from that of postinfectious acute glomerulonephritis and that there seems to exist relation between findings of C3 with progression of the glomerular lesion.

Adolescent↗
PubMedDate not supplied

[Immunopathological study in membranoproliferative glomerulonephritis].

In 39 renal percutaneous biopsies, practiced to 31 patients with membranoproliferative glomerulonephritis (GMP) with subendothelial deposits (DSE), a study with immunofluorescence technique and light microscopy was carried out. In all cases, heavy granular deposits of C3 were detected in the loops of the glomerular capillaries and in a variable proportion of cases, deposits of IgM, IgA, C3PA (factor B) and C1q of similar aspect and localizacion were found. These findings suggest immunologic pathogenesis. In the absence of C1q, no cases with factor B were found; thus, it is possible to assert that the activation of the complement system takes place exclusively through an alternate pathway, as was previously accepted. On the other hand, it was found that the presence of C1q was correlated with a faster evolution to chronic renal failure and with the presence of a higher percentage of glomeruli with extracapillary proliferation (crescents). Thus, it is concluded that activation of C1q in patients with MPG and SED, may play a role in formation of crescent and consequently, it is a sign of poor prognosis.

Adolescent↗