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Biomedical subjects

A Yi

Publications and source records attributed to A Yi.

At least 19 recordsLinked to original sources
PubMed1999

Sexual practices and prevalence of HIV, HTLV-I/II, and Treponema pallidum among clandestine female sex workers in Lima, Peru.

BACKGROUND AND OBJECTIVES: A survey was conducted to determine the sexual behavior practices and prevalence of HIV-1, HTLV-I/II, and T. pallidum infections among unlicensed female sex workers (FSWs) in Lima, Peru. GOAL OF THIS STUDY: To assess the role of unlicensed FSWs as a potential source of retroviral and T. pallidum infection. STUDY DESIGN: Female sex workers from 15 brothels were enrolled. Sera samples were obtained and tested for antibodies to HIV-1, HTLV-I, and Treponema pallidum. RESULTS: Of 158 FSWs studied, all were negative for HIV-1, 6 were positive for HTLV-I, and 5 were positive for Treponema pallidum. Of their male clients, 75% used condoms, whereas only 3% reported condom use with their steady partners. When condoms were always used by clients, the history of a sexually transmitted disease was significantly reduced (p < 0.01), and the prevalence of HTLV-I (p < 0.05) and syphilis was lower among these workers. CONCLUSION: Data suggested that the low rate of sexually transmitted diseases among FSWs reflected the high rate of condom use by their male clients.

Adult↗
PubMed1998

Topographical distribution of [125I]-glial cell line-derived neurotrophic factor in unlesioned and MPTP-lesioned rhesus monkey brain following a bolus intraventricular injection.

The present study determined the topographical distribution profile for [125I]-glial cell line-derived neurotrophic factor in unlesioned and MPTP-lesioned (unilateral intracarotid injection) rhesus monkeys following an intraventricular injection. Autoradiographic analysis showed that following a bolus intraventricular injection, there was widespread distribution of [125I]-glial cell line-derived neurotrophic factor throughout the ventricular system (walls of lateral, third, and fourth ventricles and aqueduct), with some accumulation at the lateral ventricle injection site, possibly associated with the ependymal cell layer. In both unlesioned and MPTP-lesioned monkeys, there was labelling of the cerebral cortex, substantia nigra/ventral tegmental area and sequestration of [125I]-glial cell line-derived neurotrophic factor adjacent to the hippocampal formation, globus pallidus, ventral to and in the substantia nigra. However, [125I]-glial cell line-derived neurotrophic factor did not appear to diffuse readily or accumulate in the caudate-putamen even though there was some penetration away from the ventricular walls. Throughout the brain, there was also substantial non-parenchymal labelling of [125I]-glial cell line-derived neurotrophic factor, possibly associated with extracellular matrix components, meninges and vasculature due to the heparin binding properties of glial cell line-derived neurotrophic factor. In addition to the extensive loss of tyrosine hydroxylase immunoreactivity within the substantia nigra, there was also decreased accumulation of [125I]-glial cell line-derived neurotrophic factor and reduced glial cell line-derived neurotrophic factor immunoreactivity ipsilateral to the lesion. Microscopic analysis showed that glial cell line-derived neurotrophic factor immunoreactivity was associated with upper cortical layers including a high density of immunoreactivity at the surface of the cortex (meningeal, pial layer, vasculature) and around the ventricular walls (with some cellular labelling and labelling of vasculature). Moderate staining was observed in nigral cells contralateral to the MPTP-lesion, whereas only minimal levels of that glial cell line-derived neurotrophic factor immunoreactivity were detected ipsilateral to the lesion. This study shows that intraventricularly injected glial cell line-derived neurotrophic factor accumulates not only around the ventricular walls, but also in specific brain regions in which sub-populations of cells are more readily accessible than others. The presence of cells labelled with [125I] and immunopositive for glial cell line-derived neurotrophic factor in the substantia nigra indicates that these cells are a target for the trophic factor following intraventricular administration. Thus, the behavioral improvement observed in MPTP-lesioned monkeys following an intraventricular injection of glial cell line-derived neurotrophic factor is likely the result of activation of nigral cells.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1996

Functional recovery in parkinsonian monkeys treated with GDNF.

Parkinson's disease results from the progressive degeneration of dopamine neurons that innervate the striatum. In rodents, glial-cell-line-derived neurotrophic factor (GDNF) stimulates an increase in midbrain dopamine levels, protects dopamine neurons from some neurotoxins, and maintains injured dopamine neurons. Here we extend the rodent studies to an animal closer to the human in brain organization and function, by evaluating the effects of GDNF injected intracerebrally in rhesus monkeys that have had the symptomatology and pathophysiological features of Parkinson's disease induced by the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The recipients of GDNF displayed significant improvements in three of the cardinal symptoms of parkinsonism: bradykinesia, rigidity and postural instability. GDNF administered every four weeks maintained functional recovery. On the lesioned side of GDNF-treated animals, dopamine levels in the midbrain and globus pallidus were twice as high, and nigral dopamine neurons were, on average, 20% larger, with an increased fibre density. The results indicate that GDNF may be of benefit in the treatment of Parkinson's disease.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1995

Clinical characteristics and risk factors for Vibrio cholerae infection in children.

Surveillance was conducted during February and March 1991 in the pediatric emergency department of Cayetano Heredia Hospital, Lima, Peru, to contrast the characteristics of children with epidemic cholera with those of children with noncholera-associated diarrhea. Among 626 patients 14 years of age or younger, Vibrio cholerae O1 was isolated from stool specimens of 310 patients (49%), more commonly from children older than 24 months of age (66%; p < 0.0001) than from younger children. Cholera was clinically characterized by a more sudden onset; watery diarrhea; and associated abdominal pain, muscle cramps, and vomiting, which led to more severe dehydration and hospitalization more often than in noncholera cases. Only one patient with cholera died, for a case-fatality rate of 3.2 deaths per 1000 persons. Nonpotable water and uncooked foods were identified as probable vehicles for V. cholerae. The frequency of diarrhea among relatives of patients with cholera suggested intrafamily transmission. This study of epidemic cholera describes the clinical features and the risk factors for acquisition of the infection, and points out the low case-fatality rate with prompt and appropriate treatment.

Abdominal Pain↗
PubMed1994

Clindamycin plus amikacin versus clindamycin plus aztreonam in established intraabdominal infections.

BACKGROUND: A prospective, randomized, single-blind study evaluated the efficacy and safety of clindamycin plus amikacin versus clindamycin plus aztreonam (Cl-Az) in treating intraabdominal infections in adults. METHODS: Patients were treated intravenously for 7 to 10 days, clindamycin 900 mg plus amikacin 5.0 mg/kg three times a day or clindamycin 900 mg plus aztreonam 2.0 gm three times a day. All 67 patients enrolled were evaluated for safety and 31 in each group for clinical and microbiologic response. Both groups were similar in initial diagnosis, perforated appendicitis or intraabdominal abscess. In each group 24 patients (77%) were admitted in serious condition and three (10%) in critical condition. Twenty-five patients (80.6%) in each group had aerobic and anaerobic pathogens; the remainder had either aerobic or anaerobic pathogens. RESULTS: On therapy completion, clinical and bacteriologic responses were as follows: clindamycin plus amikacin group, 26 (84%) cured, 3 (9.7%) improved, and 2 (6.3%) failed; Cl-Az group, 25 (80.7%) cured, 6 (19.3%) improved, and 0 failed. Rapid temperature decrease occurred in Cl-Az group (p = 0.007). Forty-one mild adverse medical events reported were evenly distributed, but no patients were removed as a result. CONCLUSIONS: Both combinations were highly effective in managing intraabdominal sepsis. Clindamycin aztreonam showed a slight advantage because of absence of renal toxicity and shorter time to apyrexia.

Abdomen↗
PubMed1993

Evaluation of alkaline phosphatase-labelled ipaH probe for diagnosis of Shigella infections.

The presence of many enteropathogens which are not easily detectable by routine stool culture has led to the development of alternative diagnostic methods. One of these techniques, nucleic acid probe hybridization, has been used to identify Shigella spp. and enteroinvasive Escherichia coli (EIEC) in stool specimens through the detection of genetic material encoded by a specific large approximately 200-kbp virulence-related plasmid. In the present study, an alkaline phosphatase-labelled oligonucleotide probe developed to detect the gene for ipaH, a repetitive genetic sequence thought to be present on both the virulence-related plasmid and the chromosomes of all strains of Shigella and EIEC, was tested in a developing-country setting through a prospective clinical trial. In a group of 219 Peruvian adults and children with acute gastroenteritis, the ipaH probe detected 85% of cases of shigellosis and demonstrated a specificity of 95% when compared with simultaneous detection by several stool culture techniques. Additionally, three cases of EIEC infection which could not be diagnosed by culture methods alone were detected with the ipaH probe and were confirmed by plasmid analysis and Sereny testing. These preliminary results suggest that, with further research, the ipaH probe should prove to be a useful and rapid adjunct in the diagnosis of acute gastroenteritis in developing countries.

Alkaline Phosphatase↗
PubMed1993

Comparison of three methods to obtain upper small bowel contents for culture.

In this study of 27 patients with dyspepsia, we compared three methods for obtaining upper small bowel contents for culture: 1) the Enterotest or string capsule method, 2) duodenal intubation using a closed polyethylene tube filled with water that had been boiled for sterilization and removal of dissolved oxygen, and 3) brushing of duodenal mucosa with a cytology brush protected by a sheath (the last two done during endoscopy). In 12 of the 27 patients, duplicate intubations and brushings were performed. The samples obtained were cultured aerobically. Parameters used to compare the three methods were: the contribution of each method to the diagnosis of upper small bowel bacterial overgrowth (USBBO), agreement between the methods in diagnosis of USBBO and in detailed microbiological findings, and the reproducibility of diagnosis of USBBO and of microbiological findings in duplicate intubation and brushing. Intubation and brushing were highly reproducible and superior to the Enterotest in all of the tested parameters. Intubation and brushing are equally efficacious, but intubation is preferred because of the slight cost advantage, ease of specimen processing, and the ability to obtain anaerobic specimens.

Adult↗
PubMed1992

Etiologic agents in acute vs persistent diarrhea in children under three years of age in peri-urban Lima, Perú.

In a longitudinal study of acute and persistent diarrhea in 677 children less than three years old in a peri-urban community of Lima, Perú, during 27 months of surveillance, stools were cultured at the beginning of each diarrheal episode and on each subsequent week of illness. Analyzing stool cultures only from children who had not received antibiotic treatment in the 48 h prior to the culture, no association was found between any enteropathogen and persistent diarrhea. We did not find any increase in mixed infections in persistent diarrhea episodes as compared with acute diarrhea, controlling for age, season and anthropometric status. The isolation rate for any given enteropathogen was similar during the first, second, third or later week of illness, but when the presence of a specific enteropathogen was sought in sequential stools within a single episode, no evidence of persistent infection was found. This study shows that in developing countries with a high incidence of diarrheal diseases frequent re-infections with enteropathogens prevalent in the population are one reason for prolonged illnesses. Host factors that increase susceptibility to infection or decrease recovery from illness may also play a role. Further studies of these factors, such as micronutrient deficiencies, are needed to identify a public health intervention to control persistent diarrhea, a condition associated with mortality in many developing countries.

Acute Disease↗
PubMed1992

Serological responses to various Coccidioides antigen preparations in a new enzyme immunoassay.

A new enzyme immunoassay (EIA) was used to investigate immunoglobulin M (IgM) and IgG responses to various coccidioidal antigen preparations. Direct binding and inhibition assays both revealed that the IgG responses of many serum specimens were directed largely to the tube precipitin (TP) antigen even when the microwells were coated with a combination of coccidioidal antigens (CCAs). From a panel of 28 serum specimens containing antibodies to CCAs, 4 serum specimens yielded high IgG signals (absorbance, greater than 1.0) and were negative for IgM (absorbance, less than 0.2), yet all four IgG responses were inhibited by at least 90% with partially purified TP antigens (2.4 micrograms/ml). The IgM and IgG fractions of several serum specimens were separated by ion-exchange chromatography and assayed by using different antigen preparations adsorbed to the microwells. The binding of both IgM and IgG peaks to the microwells coated with the CCA preparation was inhibited significantly by preincubation with TP antigens. One serum specimen (specimen 26) yielded a large IgG response (absorbance, greater than 2.0) with the CCA preparation and also bound directly to microwells coated only with TP antigens. The IgG signal (absorbance) of serum specimen 26 was reduced by 98% when it was preincubated with TP antigens prior to the assay. Significant IgG signals from several other serum specimens were observed when microwells were coated with TP antigen preparations, but they were absent when periodate-treated preparations were used. Two cerebrospinal fluid specimens yielded IgG signals with CCA-coated microwells, which were not inhibited by TP antigens, and yielded no signal with microwells coated only with TP antigens. The results are consistent with the concept that the typical serologic response to TP antigens occurs early in disease progression, but they suggest that TP antigens stimulate both IgM and IgG responses.

Antibodies, Fungal↗
PubMed1991

Measles-associated diarrhea in hospitalized children in Lima, Peru: pathogenic agents and impact on growth.

Because the causes of measles-associated diarrhea are not well known, 0- to 5-year-old children presenting to the hospital with measles-associated diarrhea (cases, n = 77) or acute diarrhea only (controls, n = 77) were compared. Growth and diarrheal morbidity were evaluated for 1 month after acute illness. Campylobacter jejuni was more frequently isolated from cases (31%) than controls (16%; P = .03). Rotavirus was absent in all cases versus 28% of controls (P less than .001). Incidence density for new episodes of diarrhea was significantly greater in cases (6.5 vs. 4.1; odds ratio, 1.6; confidence intervals, 1.09-2.34; P = .01), as was duration of episodes (3 vs. 2 days, P = .02). Both groups showed similar positive cumulative percentage weight gains throughout follow-up. These data support the theory of measles as a risk factor for developing diarrhea. The bacteriologic and virologic findings may reflect the immunologic response of the host to measles infection.

Acute Disease↗
PubMed1991

Prospective study of systemic and mucosal immune responses in dysenteric patients to specific Shigella invasion plasmid antigens and lipopolysaccharides.

Shigellosis is a major cause of infant morbidity and mortality in developing countries. To find immunological correlates of specific protection against shigellosis, we examined chronological samples of sera, stool extracts, duodenal aspirates, and saliva samples from 39 adults and 22 children with shigellosis from Peru for the presence of specific antibody to invasion plasmid antigens (Ipa) common to all virulent Shigella strains, by using both a whole-organism enzyme-linked immunosorbent assay (ELISA) and a Western blot (immunoblot) assay. Antibody responses to lipopolysaccharide (LPS) from Shigella serotypes both homologous and heterologous to the infecting strain were also determined by ELISA. ELISAs showed that the highest serum immunoglobulin G (IgG) antibody titers to Shigella whole organisms both with and without surface Ipa were found in adults and malnourished children, the two groups with the shortest and longest durations of disease, respectively. Mucosal IgA antibody titers to Shigella strains decreased over time to a much greater extent than serum IgG titers, and IgA to Ipa in mucosal secretions was found in adults and well-nourished children but not in malnourished children. The presence of mucosal antibody to Ipa may limit the spread and severity of the infection, as indicated by the prolonged illness observed in malnourished children who have no significant mucosal antibody to Shigella Ipa. Serum antibody titers to the Ipa antigens were high relative to anti-Shigella LPS antibody titers, especially in pediatric patients. In contrast to the anti-Ipa responses observed, no differences in antibody responses to LPS in children compared by nutritional status were found. High levels of serum and mucosal cross-reacting antibody to heterologous serotype LPS were found between Shigella flexneri serotypes 1a and 2a. Different patterns of immune response to Ipa proteins and LPS that may aid in the definition of Shigella antigens important in host protection were observed in adults, well-nourished children, and malnourished children.

Adult↗
PubMed1991

High frequency of coinfecting enteropathogens in Aeromonas-associated diarrhea of hospitalized Peruvian infants.

Rectal swabs from 391 infants less than 18 months of age who were hospitalized with acute diarrhea and from 138 similarly aged healthy infants were examined for the etiologic agents of diarrhea. Aeromonas spp. were recovered from 205 of 391 (52.4%) diarrheic patients, whereas they were recovered from 12 of 138 (8.7%) controls (P less than 10(-11). Among the 205 Aeromonas-positive diarrheic patients, 118 (57.6%) were found to be coinfected with other common enteropathogens. Of the 164 Aeromonas-positive initial diarrheic specimens, 82 (50.0%) had one or more other enteropathogens present; 30 patients were coinfected with rotavirus, 20 with enterotoxigenic Escherichia coli, 16 with Campylobacter spp., 14 with Shigella spp., 13 with enteropathogenic E. coli, 4 with Vibrio spp., 1 with Salmonella spp., and 1 with Plesiomonas spp. of Aeromonas strains from cases compared with that from controls supports an etiologic role for this organism. However, frequent concomitant infections with other well-recognized enteropathogens and a lack of disease correlation with common Aeromonas phenotypes suggest that only a subset of Aeromonas strains may be diarrhea causing and that such strains may be common to several of the existing species.

Aeromonas↗
PubMed1990

Laboratory observations on Plesiomonas shigelloides strains isolated from children with diarrhea in Peru.

Eleven strains of Plesiomonas shigelloides isolated from 10 Peruvian children with diarrhea were examined. All the strains were resistant to two or more antibiotics, most commonly ampicillin, gentamicin, erythromycin, kanamycin, and streptomycin. The strains were all negative in the Sereny and cell culture assays used to test for enteroinvasiveness. One strain showed cytotoxic activity on Vero cells. The strains showed no antigenic relationship with Shigella organisms. Both bioassays and enzyme-linked immunosorbent assays used for detection of Escherichia coli enterotoxins were negative. Nucleic acid probes for such toxins likewise gave negative results. The strains all possessed a large (approximately 200-megadalton) plasmid in addition to one or more other plasmids. Several different plasmid profiles were observed among these 11 P. shigelloides strains, indicating that the isolates were not acquired from a common source or from a single bacterial clone.

Child↗
PubMed1989

Assessment of HIV-1 screening test sensitivities using serially diluted positive sera can give misleading results.

Three FDA licensed HIV-1 viral lysate and two nonlicensed recombinant antigen assays were used to evaluate six serially diluted plasma samples and 2 highly characterized seroconversion series. The sensitivity as measured by serial dilution did not necessarily correlate with the sensitivity as measured by seroconversion performance with the lysate and the recombinant assays. It is concluded that national licensing agencies should arrange to share seroconversion panels to evaluate accurately the sensitivity of new HIV-1 screening tests.

Diagnostic Errors↗
PubMed1989

Comparison of single-dose treatment with norfloxacin and standard 5-day treatment with trimethoprim-sulfamethoxazole for acute shigellosis in adults.

Shigellae have been shown to be highly susceptible to new quinolone agents, with average MICs for 90% of isolates of less than 0.1 microgram/ml. Because these agents also reach high concentrations in the stool after a single dose, the effectiveness of a single 800-mg dose of norfloxacin and of 5-day treatment with trimethoprim-sulfamethoxazole (TMP-SMX) were compared in a randomized trial. Patients with clinical dysentery received one of these treatment regimens, and clinical data and follow-up culture results were analyzed for patients whose stool culture on presentation grew shigellae. When 55 patients with shigellosis (26 treated with TMP-SMX, 29 treated with norfloxacin) whose bacterial isolates were susceptible to the antibiotic given were compared by treatment group, no significant differences were seen in days of illness (mean, 2.5 +/- 0.65 days with TMP-SMX and 2.0 +/- 0.47 days with norfloxacin; P = 0.200) or number of unformed stools after starting treatment (mean, 9.7 +/- 2.37 stools with TMP-SMX and 7.6 +/- 3.19 stools with norfloxacin; P = 0.312). Resistance in vitro to TMP-SMX was seen in 15% of Shigella isolates, whereas none was resistant to norfloxacin. Bacteriologic failure was found in 1 patient among 24 receiving TMP-SMX and in none of 25 patients receiving norfloxacin. One single dose of norfloxacin was as effective as 5 days of treatment with TMP-SMX in these adults with shigellosis.

Adult↗
PubMed1989

Furazolidone and chloramphenicol for treatment of typhoid fever.

Seventy-one adults who were hospitalized between March 1985 and March 1987 were entered into a randomized, double-blind study to compare the efficacy and safety of furazolidone and chloramphenicol in therapy for typhoid fever. Patients received chloramphenicol capsules (total daily dosage, 2 g) plus placebo tablets for furazolidone tablets (total daily dosage, 800 mg) plus placebo capsules for 14 days. Seven patients were excluded from the analysis of efficacy because blood, bile, or bone marrow cultures at admission failed to demonstrate the presence of Salmonella typhi. Four additional patients were excluded because of intercurrent illness or failure to return for follow-up visits. Cure was achieved in 31 (97%) of 32 chloramphenicol recipients and 24 (86%) of 28 furazolidone recipients. In the chloramphenicol group, one patient experienced moderate sideroblastic anemia, and another experienced moderate neutropenia. Both adverse reactions resolved spontaneously within 7 days. Mild gastritis was reported by two patients who received furazolidone and one who received chloramphenicol. This study has demonstrated that furazolidone is an effective and safe alternative to chloramphenicol for the treatment of typhoid fever in adults.

Adult↗