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Biomedical subjects

J Sanchez

Publications and source records attributed to J Sanchez.

At least 19 recordsLinked to original sources
PubMed2000

Emerging genetic diversity of HIV-1 in South America.

OBJECTIVE: Genotype determination and risk group analysis of HIV-1 infected individuals in selected regions of South America. DESIGN: Cross-sectional convenience sampling of HIV-1-positive individuals in Peru, Ecuador, Uruguay and Paraguay from March, 1994 through September, 1998. METHODS: HIV-1-positive subjects were identified through the national AIDS surveillance program in each country. A standardized questionnaire was used to obtain demographic, clinical and risk factor data on each study subject. Viral DNA was extracted from participants' peripheral blood mononuclear cells either directly or after co-cultivation. A nested PCR was used to obtain selected fragments of the envelope genes for genotyping by the heteroduplex mobility assay (HMA). A 600 bp sequence encompassing the V3 loop was sequenced from a selection of 23 of these samples for phylogenetic analysis and confirmation of HMA genotype. RESULTS: Among the 257 successfully genotyped HIV-1-positive samples, genotype B was found in 98.3% (228/232) of those obtained from subjects in Peru, Ecuador, and Paraguay. In contrast, 56% (14/25) of the samples from Uruguay were genotype F, and the remainder were genotype B. Genotype F was detected for the first time in Peru (2/224) and Paraguay (1/4), and genotype A for the first time in Peru (1/224). Phylogenetic analysis confirmed the genotype identified by HMA in the 23 samples sequenced. There was no detectable genetic clustering of HIV-1 within the different high-risk groups or geographic locations. CONCLUSIONS: These findings verify and extend the presence of several different HIV-1 genotypes in South America.

Amino Acid Sequence↗
PubMed2000

Molecular analysis of lineage-specific chimerism and minimal residual disease by RT-PCR of p210(BCR-ABL) and p190(BCR-ABL) after allogeneic bone marrow transplantation for chronic myeloid leukemia: increasing mixed myeloid chimerism and p190(BCR-ABL) detection precede cytogenetic relapse.

We studied lineage-specific chimerism and minimal residual disease (MRD) in sequential posttransplant samples from 55 patients who underwent unmanipulated (n = 44) or partially T-cell-depleted (n = 11) allogeneic bone marrow transplantation (BMT) for chronic myeloid leukemia (CML). Chimerism was assessed by polymerase chain reaction (VNTR [variable number of tandem repeats]-PCR) analysis in highly purified CD19+, CD3+, CD15+, and CD56+ cell fractions, whereas MRD was investigated in whole blood by reverse transcriptase-PCR (RT-PCR) of both p210(BCR-ABL) and p190(BCR-ABL) hybrid transcripts. Of 55 patients, 14 (including 6 T-cell-depleted patients) had cytogenetic relapse at 5-80 months and progressed to hematologic relapse, while 41 patients remained in prolonged cytogenetic remission 12-107 months post-BMT. Before leukemia recurrence, patients in the relapse group showed a consistent evolution pattern sequentially featured by persistent p210(BCR-ABL) positivity, increasing mixed chimerism (MC) in myeloid cells, p190(BCR-ABL) positivity, and, finally, cytogenetic relapse. Myeloid MC preceded cytogenetic relapse by 2-12 months, whereas p190(BCR/ABL) was detected 1-6 months prior to cytogenetic relapse in 11 patients and concomitant with cytogenetic relapse in 3 patients. In the remission group, all patients invariably tested negative for p190(BCR-ABL); 10 patients tested positive for p210(BCR-ABL) at variable time-points but showed persistent full donor chimerism (DC), whereas 31 patients tested p210(BCR-ABL) negative and displayed full DC or transient MC due to the persistence of recipient T cells. Two patients in the relapse group were successfully reinduced into molecular remission with donor lymphocyte infusion. Sequential molecular analysis after such treatment showed the inverse pattern to that observed prior to relapse, ie, progressive disappearance of p190(BCR-ABL) transcripts, conversion of myeloid chimerism to donor type, and, finally, p210(BCR-ABL) negativity. We conclude that lineage-specific chimerism and p190(BCR-ABL) messenger RNA (mRNA) analyses contribute a better characterization of CML evolution after BMT and enable early identification of patients at the highest risk of relapse. (Blood. 2000;95:2659-2665)

Adolescent↗
PubMed2000

Lipoxygenase pathway in olive callus cultures (Olea europaea).

Stimulation of the lipoxygenase pathway in olive fruit initiates a cascade of reactions that begins with the regio- and stereospecific di-oxygenation of polyunsaturated fatty acids containing a cis, cis-1,4 pentadiene moiety. Later products of the pathway include volatiles that influence the organoleptic properties of harvested olive oil. In this study, we have investigated lipoxygenase activity in olive callus cultures, and found that there is evidence of several isoforms of the enzyme with different pH optima and substrate specificities. Endogenous lipoxygenase activity was detected throughout the growth cycle of olive callus, particularly during the log phase of growth, suggesting that olive lipoxygenases are intimately involved in growth. The most prominent lipoxygenase activity in tissue cultures was found to be soluble but significant activities were detected in the plastid fraction. In addition, hydroperoxide lyase (HPL) activity was measured in the calli; both 13- and 9-HPL activities were found which were particulate.

Aldehyde-Lyases↗
PubMed2000

Isolation and hypoglycemic activity of 5, 7,3'-trihydroxy-3,6,4'-trimethoxyflavone from Brickellia veronicaefolia.

Hypoglycemic activity-guided fractionation together with chemical analysis led to the isolation of one flavone (5, 7,3'-trihydroxy-3,6,4'-trimethoxyflavone) from the chloroform extract of the leaves of Brikkellia veronicaefolia. Identification was based on spectroscopic methods. The isolated flavone was tested for hypoglycemic activity in normal and alloxan-diabetic CD1 mice (25-30 g) were administered in doses of 10, 25 and 50 mg/kg body weight. The blood glucose levels were determined before and 1.5, 3, 4.5 and 24 hours after drug administration. The results showed that the flavone produces a significant hypoglycemic effect in normal as well as in diabetic mice. Comparison was made between the action of the flavone and a known hypoglycemic drug as tolbutamide (50 mg/kg). The flavone was found to be slow and less effective than tolbutamide.

Alloxan↗
PubMed2000

Molecular structures and vibrations of m-methylaniline in the S0 and S1 states studied by laser induced fluorescence spectroscopy and ab initio calculations.

The UV fluorescence excitation and dispersed fluorescence spectra of a jet-cooled m-methylaniline have been obtained for the S1<--S0 transition, in which some of the bands have been observed for the first time. The main spectral bands have been assigned by comparison with those of other relevant substituted benzenes. It was found that the spectra exhibit an important feature which is the internal rotation of the methyl group in the electronic ground and excited states. Ab initio calculations at MP2/6-31G* and CIS/6-31G* show that the optimized structure of m-methylaniline in the ground state is not planar with the amino group having sp3 hybridation-like character due to the existence of lone-paired electrons on the nitrogen atom. Upon electronic excitation, the C-N bond exhibits a partial double bond character, indicating an enhanced interaction between the ring and the NH2 group as in the case of aniline.

Aniline Compounds↗
PubMed2000

First injection and current risk factors for HIV among new and long-term injection drug users.

The purpose of this paper is to estimate HIV seroprevalence and to examine the injection and sexual risk behaviours of a cohort of active new heroin injectors who have initiated injection within the past four years and to compare their risk behaviours with those of long-term heroin injectors who initiated injection prior to January 1, 1985. A stratified network-based sample was used to recruit injection drug users (IDUs) from the streets of Miami-Dade, Florida. New IDUs displayed a significantly lower HIV seroprevalence than long-term injectors (13.3 versus 24.7%). Both new and long-term drug injectors exhibited a high level of current HIV risk behaviour. While new injectors were more likely than long-term injectors to practise safer injection behaviours at the initial injection episode, the current risk behaviours of new and long-term injectors are similar.

Adult↗
PubMed1999

Resources and estuarine health: perceptions of elected officials and recreational fishers.

It is important to understand the perceptions of user groups regarding both the health of our estuaries and environmental problems requiring management. Recreational fishers were interviewed to determine the perceptions of one of the traditional user groups of Barnegat Bay (New Jersey), and elected officials were interviewed to determine if the people charged with making decisions about environmental issues in the bay held similar perceptions. Although relative ratings were similar, there were significant differences in perceptions of the severity of environmental problems, and for the most part, public officials thought the problems were more severe than did the fishers. Personal watercraft (often called Jet Skis) were rated as the most severe problem, followed by chemical pollution, junk, overfishing, street runoff, and boat oil. Small boats, sailboats, wind surfers, and foraging birds were not considered environmental problems by either elected officials or fishermen. The disconnect between the perceptions of the recreational fishers and those of the locally elected public officials suggests that officials may be hearing from some of the more vocal people about problems, rather than from the typical fishers. Both groups felt there were decreases in some of the resources in the bay; over 50% felt the number of fish and crabs had declined, the size of fish and crabs had declined, and the number of turtles had declined. Among recreational fishers, there were almost no differences in perceptions of the severity of environmental problems or in changes in the bay. The problems that were rated the most severe were personal watercraft and overfishing by commercial fishers. Recreational fishers ranked sailboats, wind surfers, and fishing by birds as posing no problem for the bay. Most fishers felt there had been recent major changes in Barnegat Bay, with there now being fewer and smaller fish, fewer and smaller crabs, and fewer turtles. The results suggest that the views of a wide range of coastal users should be considered when making environmental health decisions.

Adult↗
PubMed1999

Single-step PCR amplification and enzyme restriction analysis of the entire Helicobacter pylori cytotoxin vacA gene for genetic variability studies.

To monitor changes along the entire Helicobacter pylori vac A gene we carried out full-length single-step PCR amplification in 21 gastritis and gastric cancer isolates. HindIII restriction analysis led us to detect a > 400-bp internal insertion in vacA subsequently shown to be a direct 451-bp gene duplication. We found HindIII profiles for 16 genes that allowed their grouping into two restriction patterns that were related to theoretical profiles for previously sequenced Western genes. Comparisons with theoretical HindIII patterns for Japanese isolates appear suggestive of geographical H. pylori clonality. Full-length single-step PCR amplification seems suitable for quick restriction pattern assignment and detection of gene size changes.

Bacterial Proteins↗
PubMed1999

Purification, characterization, and role of nucleases and serine proteases in Streptomyces differentiation. Analogies with the biochemical processes described in late steps of eukaryotic apoptosis.

Two exocellular nucleases with molecular masses of 18 and 34 kDa, which are nutritionally regulated and reach their maximum activity during aerial mycelium formation and sporulation, have been detected in Streptomyces antibioticus. Their function appears to be DNA degradation in the substrate mycelium, and in agreement with this proposed role the two nucleases cooperate efficiently with a periplasmic nuclease previously described in Streptomyces antibioticus to completely hydrolyze DNA. The nucleases cut DNA nonspecifically, leaving 5'-phosphate mononucleotides as the predominant products. Both proteins require Mg2+, and the additional presence of Ca2+ notably stimulates their activities. The two nucleases are inhibited by Zn2+ and aurin tricarboxylic acid. The 18-kDa nuclease from Streptomyces is reminiscent of NUC-18, a thymocyte nuclease proposed to have a key role in glucocorticoid-stimulated apoptosis. The 18-kDa nuclease was shown, by amino-terminal protein sequencing, to be a member of the cyclophilin family and also to possess peptidylprolyl cis-trans-isomerase activity. NUC-18 has also been shown to be a cyclophilin, and "native" cyclophilins are capable of DNA degradation. The S. antibioticus 18-kDa nuclease is produced by a proteolytic processing from a less active protein precursor. The protease responsible has been identified as a serine protease that is inhibited by Nalpha-p-tosyl-L-lysine chloromethyl ketone and leupeptin. Inhibition of both of the nucleases or the protease impairs aerial mycelium development in S. antibioticus. The biochemical features of cellular DNA degradation during Streptomyces development show significant analogies with the late steps of apoptosis of eukaryotic cells.

Amino Acid Sequence↗
PubMed1999

Perceptions of on-site hunters: environmental concerns, future land use, and cleanup options at the Savannah river site.

The Department of Energy owns land in 34 states, and most of these lands have been off limits to the public for over 50 years. Although some parts of each site are contaminated, most of many sites are not. With the ending of the Cold War, the department is considering alternative land uses. In this article, the perceptions of hunters and fishermen allowed on site for a limited time were examined, about environmental concerns, future land use, and cleanup options. Although loss of jobs was the foremost concern, preserving parts of the site had more support as a future land use than continuing the nuclear mission, and nearly three-quarters of the sample supported cleanup, regardless of cost. On-site employment was a significant indicator of lower concern about safety and environmental issues, less support for designating the site for research, and more concern for maintaining jobs.

Adolescent↗
PubMed1999

A cloning vector for efficient generation of cholera toxin B gene fusions for epitope screening.

Gene fusion proteins with epitopes attached to the amino end of cholera toxin B subunit (CTB) are useful to raise immunological responses. We describe a cloning vector, designated pCTBtet, carrying a tetracycline resistance gene (TetR) between the leader peptide and mature CTB. Removal of TetR to insert oligonucleotides encoding fusion epitopes allowed for screening of tetracycline-sensitive clones. Restoration of the correct CTB reading phase was subsequently used to choose gene fusion candidate colonies. The use of pCTBtet permitted the rapid construction of 8 fusion proteins carrying 9-24 aa from Salmonella typhi OmpC and 6 hybrids with 7-31 aa from Escherichia coli colonization factor CFAI.

Amino Acid Sequence↗
PubMed1999

Pseudocyst of the umbilical cord: prenatal sonographic appearance and clinical significance.

OBJECTIVE: To assess the clinical significance of umbilical cord pseudocysts detected prenatally by sonography. METHODS: The prenatal sonographic findings, karyotype, and perinatal outcome in 13 fetuses with umbilical cord pseudocysts were reviewed retrospectively. RESULTS: Umbilical cord pseudocysts were diagnosed at a median gestation of 27 weeks (range 15-37). Pseudocysts were single in eight cases with cyst diameters ranging from 20 to 50 mm, and double in one case. In the remaining four cases, multiple small cystic masses measuring less than 8 mm were identified. Additional sonographic findings were noted in 11 cases; ten of these fetuses had prenatal karyotyping, which showed trisomy 18 in five cases, trisomy 13 in one case, and a 46,XX, inv ins(18;21) complement in one case. Among the seven chromosomally abnormal fetuses, umbilical cord pseudocysts were multiple in four fetuses and single in three. All chromosomally abnormal fetuses and two euploid fetuses with associated structural defects died in utero or in the neonatal period. There were no perinatal complications in either of the fetuses with isolated pseudocysts. CONCLUSION: The prenatal sonographic appearance of umbilical cord pseudocysts varied widely. These umbilical cord cystic masses were associated strongly with chromosomal disorders and structural defects, regardless of their sonographic appearance in utero.

Adult↗
PubMed1999

Epidemiological study of the prevalence of allergic reactions to Hymenoptera in a rural population in the Mediterranean area.

BACKGROUND: Systemic allergic reactions to Hymenoptera venom occur in a percentage that varies from 0.4 to 3.3%. Epidemiological studies indicate that from 15 to 25% of the general population can be sensitized to different Hymenoptera venom as well as the fact that the degree of exposure may be related to the prevalence found in those studies. OBJECTIVE: The objective of this study was to evaluate the prevalence of insect sting allergy and the venom sensitization in a rural population to three Hymenoptera previously found in the area: Polistes dominulus (Pd), Vespula germanica (Vg) and honey bee (Hb). METHODS: A rural community located in the south-east of Spain, close to the Mediterranean Sea, was selected since the stinging Hymenoptera having been previously identified. A random sample of 310 subjects from the village census was studied. A questionnaire and a serum sample were obtained from every patient. The evaluation was conducted by a family doctor, who focused on the reactions to Hymenoptera sting, age, sex, occupation, atopia, previous Hymenoptera sting, stinging insect, interval to last sting and average stings per year. RAST to Hymenoptera venoms were also determined. RESULTS: The prevalence of systemic reactions was 2.3% (57.6% of them had a positive RAST). Large local reactions were found in 26.4% (only 28.5% of them had a positive RAST). Asymptomatic sensitization (positive RAST) was observed in 16.4% of subjects without reaction. Only a weak correlation between subjects with less than 3 years' interval to last sting exposure and positive RAST results was noted, whether they presented with a clinical reaction or not (P < 0.05). CONCLUSIONS: The prevalence of systemic sting reactions in our rural community is higher than other general populations in the same Mediterranean area, and similar to other rural populations studied. The degree of exposure influences not only the prevalence found but also the detection of specific serum IgE.

Adolescent↗
PubMed1999

Temporal variations in blood glutathione peroxidase (GSHPx) activity in sheep at pasture in a Mediterranean area.

The present study evaluates blood GSHPx activity in 18 sheep flocks at range, to identify those seasons with the highest risk of selenium deficiency. Samples were taken from 1108 15-day-old lambs during the two usual lambing periods in this geographical area (autumn-winter and spring-summer). The overall mean values in the first period (146.69 +/- 3.41 i.u./g Hb) was higher than in the second one (107.50 +/- 3.53 i.u./g Hb). This may be explained by the special features of the climate in the Mediterranean area, which allow an optimum growth of grass from October to May. Therefore, the lambs born in spring-summer are from pregnancies in months when feeding is based only upon grazing. However, lambs born in autumn-winter comes from ewes gestating during the summer, when supplementation with cereal grains is given. As a conclusion, lambs born in spring-summer in this area are at higher risk to selenium-deficiency related disorders.

Animals↗
PubMed1999

Double-blind, randomized, placebo-controlled assessment of chloroquine/primaquine prophylaxis for malaria in nonimmune Colombian soldiers.

To improve upon the efficacy of primaquine prophylaxis for malaria (94%, Plasmodium falciparum malaria; 85%, Plasmodium vivax malaria), we administered chloroquine (300 mg weekly) in combination with primaquine (30 mg daily) to nonimmune Colombian soldiers during 16 weeks of patrol in a region of endemicity and for a further 1 week in base camp. The occurrence of symptomatic parasitemia was determined during those 17 weeks and during a further 3 weeks in base camp. The protective efficacy for the chloroquine/primaquine treatment group of 100 subjects, compared with that for the placebo treatment group of 51 subjects, was 88% (95% confidence interval [CI], 76-94) against all types of malaria, 89% (95% CI, 61-97) against P. falciparum malaria, and 88% (95% CI, 58-93) against P. vivax malaria. Two chloroquine/primaquine recipients had severe gastrointestinal distress. Comparison of these data with data from a previous study indicates that the addition of chloroquine did not increase the prophylactic efficacy of primaquine.

Antimalarials↗
PubMed1999

Neurological characteristics of HIV-infected men and women seeking primary medical care.

We examined the neurological differences between human immunodeficiency virus (HIV)-infected men (n = 193) and women (n = 41) receiving primary medical care. There was no difference between men and women in the rate of HIV-related neurological syndromes (i.e. polyneuropathy, myelopathy, myopathy, HIV- dementia [HAD]). A logistic regression analysis indicated that low CD4+ cell count predicted all neurological syndromes. In addition, HAD was predicted by intravenous-drug use and lower education level, while neuropathy was associated with older age and with race. These findings indicate that there are no differences in the rate of neuropsychiatric disorders attributable to gender. The presence of other factors (e.g. drug abuse) could explain previously reported gender differences in neurological manifestations of HIV infection.

AIDS Dementia Complex↗
PubMed1999

Transient transcriptional activation of the Vibrio cholerae El Tor virulence regulator toxT in response to culture conditions.

Vibrio cholerae El Tor require special in vitro culture conditions, consisting of an initial static growth period followed by shift to shaking (AKI conditions), for expression of cholera toxin (CT) and toxin coregulated pili (TCP). ToxT, a regulator whose initial transcription depends on the ToxR regulator, positively modulates expression of CT and TCP. To help understand control of CT and TCP in El Tor vibrios, we monitored ctxAB and ToxR-dependent toxT transcription by time course primer extension assays. AKI conditions stimulated CT synthesis with an absence of ctxAB transcription during static growth followed by induction upon shaking. ToxR-dependent toxT transcription was induced at the end of the static growth period but was transient, stopping shortly after shaking was initiated but, interestingly, also if the static phase was prolonged. Immunoblot assays showed that ToxR protein levels were not coincidentally transient, implying a protein on/off switch mechanism for ToxR. Despite the transient activation by ToxR, transcription of ctxAB was maintained during shaking. This finding suggested continued toxT expression, possibly through relay transcription from another promoter. The 12.6-kb distant upstream tcpA promoter responsible for expression of the TCP operon has been proposed to provide an alternate toxT message by readthrough transcription. Activation of the tcpA promoter is supported by increased expression of TcpA protein during the shaking phase of the culture. Readthrough transcription of toxT from tcpA would be compatible with reverse transcription-PCR evidence for a toxT mRNA at times when ToxR-dependent transcription was no longer detectable by primer extension.

Bacterial Outer Membrane Proteins↗