Biomedical subjects

M Blanco

Publications and source records attributed to M Blanco.

At least 163 records · Page 9Linked to original sources

PubMed1994

Serological response to rotavirus infection in newborn infants.

We report the identification of rotavirus in stools of newborn infants at the "Hospital Materno Infantil de Caricuao" (HMIC) as well as the infants' serological responses to various rotavirus strains. The serological responses of another group of rotavirus-positive neonates studied previously at the "Maternidad Concepcion Palacios" (MCP) hospital was also evaluated. Fifty-four of 266 (20%) newborns examined at HMIC shed rotavirus. The infection rate was higher among infants admitted to the nursery (75%) than in those "rooming in" with their mothers (7%) (P < .01). Eleven of the 54 neonates (20%) had diarrhea; seven of them experienced mild, short-lived episodes, whereas five had frequent diarrhea bouts or diarrhea lasting for over 3 days; the remaining 43 infants were asymptomatic. Twenty-seven of 28 rotavirus specimens tested at HMIC had VP7 serotype 4 specificity and one belonged to VP7 serotype 1; VP4 typing performed on 24 of the viruses by RNA hybridization showed these viruses to be similar to the M37 strain, a rotavirus previously associated with asymptomatic infections in newborns at MCP. IgA seroresponses were detected in eight of 11 infants born at HMIC (73%), but most failed to developed neutralization responses to homologous or heterologous strains. Newborn infants who had shed the M37 rotavirus strain at MCP reacted similarly: 16 of 24 (67%) developed a rotavirus IgA rise, but only 29% developed a neutralization response.

Antibodies, Viral↗

PubMed1994

Evaluation of the antigenicity and reactogenicity of varying formulations of the rhesus rotavirus-based quadrivalent and the M37 rotavirus vaccine candidates.

Three phase I trials of the rhesus rotavirus (RRV)-based quadrivalent vaccine [composed of serotype 3 (RRV), and serotypes 1 (D x RRV), 2 (DS1 x RRV), and 4 (ST3 x RRV) human rotavirus x RRV reassortants] and the M37 (nursery strain) rotavirus vaccine candidates were conducted in an attempt to find a safe and optimally antigenic formulation. Infants 10-20 weeks old received, in trial I, 1) the quadrivalent vaccine as two separate bivalent doses (1 x 10(4) PFU each of D x RRV and RRV, followed 4 weeks later by 1 x 10(4) PFU each of DS1 x RRV and ST3 x RRV) or 2) placebo; in trial II, 1) one dose of quadrivalent vaccine (10(4) PFU of each component), or 2) two doses of quadrivalent vaccine, or 3) a 10(4) PFU dose of M37 vaccine, or 4) M37 vaccine followed by the quadrivalent vaccine, or 5) placebo; in trial III, 1) a dose of a higher-titered quadrivalent vaccine (10(5) PFU of each component), or 2) two doses of higher titered quadrivalent vaccine, or 3) a dose of higher titered M37 vaccine (10(5) PFU) or 4) two doses of M37 vaccine (10(5) PFU), or 5) M37 vaccine (10(5) PFU) followed by the higher titered quadrivalent vaccine, or 6) placebo. A mild, transient fever during the first week postvaccination was associated with the bivalent or quadrivalent vaccines but not with the M37 vaccine. Fourfold or greater serum IgA ELISA responses to rotavirus were observed in 48-92% of the infants receiving quadrivalent vaccine and in 32-50% of those receiving M37 vaccine.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Viral↗

PubMed1994

Serotypes of CNF1-producing Escherichia coli strains that cause extraintestinal infections in humans.

The O:K:H serotypes of 137 necrotoxigenic Escherichia coli (NTEC) producing the cytotoxic necrotizing factor type 1 (CNF1) isolated from human extraintestinal infection were determined. Although NTEC producing CNF1 belonged to 58 different serotypes, only 10 of them accounted for 54% of strains. The most common serotypes, in order of frequency, were: O4:K?:H5, O6:K13:H1, O83:K1:H31, O75:K95:H5, O2:K1:H6, O2:K7:H-, O75:K1:H7, O2:K?:H1, O4:K12:H1 and O22:K13:H1. CNF1 strains of serotypes O2:K7:H- and O4:K12:H1 express P-fimbriae, whereas CNF1 strains of serotypes O2:K?:H1, O2:K1:H6 and O75:K95:H5 possess the adhesin responsible for MRHA type III. Among CNF1 strains of serotype O4:K?:H5 there exist some that express P-fimbriae and others that possess MRHA type III. Lastly, the majority of CNF1 strains of serotypes O6:K13:H1, O22:K13:H1, O75:K1:H7 and O83:K1:H31 do not express P-fimbriae nor the adhesin responsible to MRHA type III. Our results show that extraintestinal infections are caused by a limited number of virulent clones, as suggested by the theory of special pathogenicity.

Adhesins, Bacterial↗

PubMed1994

Serotypes, toxins and antibiotic resistance of Escherichia coli strains isolated from diarrhoeic and healthy rabbits in Spain.

One hundred and ten Escherichia coli strains isolated from diarrhoeic and healthy rabbits from 50 Spanish commercial farms were serotyped and investigated for production of enterotoxins (LT and STa), verotoxins (VT), cytotoxic necrotizing factors (CNF1 and CNF2), alpha-haemolysin (Hly) and enterohaemolysin (EntHly), for necrotic and lethal activities and for antibiotic resistance. Six serogroups (O2, O26, O49, O92, O103 and O128) accounted for 81% (67 of 83) and 26% (7 of 27) respectively of E. coli strains isolated from diarrhoeic and healthy rabbits (P < 0.001). The most common serotypes found among E. coli strains associated with diarrhoeic rabbits in order of frequency were: O103:K-:H2, O49:K?:H2, O26:K-:H-, O26:K-:H11, O128:K?:H-, O92:K-:H2 and O2:K5:H6. E. coli strains belonging to the same serotype but from different farms usually showed a distint antibiotics resistance pattern. Only one strain, of serotype O2:K5:H6 was toxigenic (CNF1+, Hly+, necrotic and lethal).

Animals↗

PubMed1994

Genes coding for Shiga-like toxins in bovine verotoxin-producing Escherichia coli (VTEC) strains belonging to different O:K:H serotypes.

Forty-six verotoxin-producing Escherichia coli (VTEC) strains isolated from diarrhoeic and healthy calves in Spain were examined for DNA sequences homologous to genes for verotoxins (VT1 and VT2) and enterotoxins (LT-I, LT-II, STaH, STaP and STb). Hybridisation showed that 26 (57%) of VTEC strains carried VT1 genes, 13 (28%) possessed VT2 genes, and 7 (15%) carried both VT1 and VT2 genes. No VTEC strains hybridised with DNA probes for enterotoxins. A correlation was found between the serotype and type of VT produced. Thus, all strains of serotypes O26:K-:H11 (13 strains), O103:K-:H2 (3 strains) and O128:K?:H- (4 strains) hybridised with the VT1 probe only, whereas all strains of serotypes O4:K-:H4 (3 strains) and O113:K-:H21 (4 strains) were positive with the VT2 probe only. By contrast, O81:K?:H28 (2 strains) and O157:K-:H- (2 strains) strains hybridised with both VT1 and VT2 probes. One strain of serotype O157:K-:H7 was VT2 positive.

Animals↗

PubMed1994

Serotypes of bovine Escherichia coli producing cytotoxic necrotizing factor type 2 (CNF2).

The serotypes of 101 faecal bovine necrotoxigenic Escherichia coli (NTEC) producing the cytotoxic necrotizing factor type 2 (CNF2) were determined. Although, NTEC producing CNF2 belonged to 48 different O:K:H serotypes, only eleven of them accounted for 54% of strains. The most common serotypes in order of frequency were: O123:K-:H16, O3:K-:H21, O88:K-:H8, O15:K14:H21, O1:K-:H12, O1:K1:H46, O2:K1:H5, O55:H21, O88:K?:H25, O117:K?:H21 and O123:K-:H-. The serotypes of CNF2 NTEC were different from those found in NTEC producing CNF1 and in enterotoxigenic, verotoxigenic, enteropathogenic, enteroinvasive and enteroadherent E. coli strains that cause infections in humans and animals.

Animals↗

PubMed1994

Spectrophotometric determination of pharmaceutical dosages by partial least-squares calibration.

Partial least-squares calibration was used for the spectrophotometric determination of the active compound and preservative in a syrup also containing several light absorbing excipients. The calibration matrix was constructed from laboratory-made mixtures of the analytes and excipients and was used to quantify three samples from different batches. The most suitable conditions for quantitation were determined and the results obtained are compared with those provided by HPLC.

Butyrophenones↗

PubMed1994

Mycobacterial spindle-cell pseudotumor of the spleen.

A case of spindle-cell pseudotumor of the spleen due to nontuberculous mycobacteria in a patient with acquired immunodeficiency syndrome (AIDS) is described. The patient was a 55-year-old, human immunodeficiency virus-positive Haitian man who died of acute neurologic complications while on treatment for central nervous system toxoplasmosis. At autopsy, an enlarged multinodular spleen was noted. Histologic examination revealed coarse nodules of splenic parenchyma replaced by a dense spindle cell proliferation, admixed with scattered inflammatory cells. Immunostains showed strong cytoplasmic positivity of the spindle cells with MAC 387, HAM 56, and alpha-1-antichymotrypsin antibodies and negative staining for actin, vimentin, and S-100 protein antibodies. Ziehl-Neelsen stains revealed numerous elongated acid-fast bacilli within the cytoplasm of the cells that were occasionally lying free within the interstitium. The organisms also had a strongly positive reaction with antibodies to desmin intermediate filaments. Mycobacterial spindle-cell pseudotumor should be included in the differential diagnosis of conditions affecting the spleen in patients with AIDS.

AIDS-Related Opportunistic Infections↗

PubMed1994

Poor transduction efficiency of human hematopoietic progenitor cells by a high-titer amphotropic retrovirus producer cell clone.

The transduction efficiency of human bone marrow CD34+ cells with supernatants from the retrovirus producer cell clone PA317/LGSN 16 was only one-fifth of that with supernatants from GP+ envAm12/LGSN 15, even though both producers had similar infection titers on 3T3 cells. PA317/LGSN 16-conditioned medium inhibited the proliferation of the bone marrow CD34+ cells, and this inhibitory effect was partially blocked by anti-transforming growth factor beta antibodies. These studies suggest that cytokine secretion plays a role in the suppression of retrovirus transduction of human CD34+ cells.

3T3 Cells↗

PubMed1994

Virulence factors and O groups of Escherichia coli strains isolated from cultures of blood specimens from urosepsis and non-urosepsis patients.

Ninety-six Escherichia coli strains isolated from cultures of blood specimens taken from both urosepsis patients (n = 48) and non-urosepsis patients (n = 48) were examined for the production of alpha-haemolysin (Hly) and cytotoxic necrotizing factor type 1 (CNF1), the expression of P-fimbriae and mannose-resistant haemagglutination (MRHA). Twenty-seven (56%) of the E. coli strains from urosepsis showed some of the virulence factors investigated, whereas only 15 (31%) of the strains associated with non-urosepsis possessed virulence factors (P < 0.05). By contrast, only 16% (P < 0.001) of the faecal isolates from healthy individuals were virulent. Of the bacteremic E. coli strains, 56 (58%) belonged to one of 8 serogroups (O1, O2, O4, O6, O8, O9, O18 and O83). Virulence factors were concentrated in strains belonging to serogroups O2, O4, O6, O18 and O83. Thus, 23 (72%) of the 32 strains of these 5 groups showed virulence factors, but only 19 (30%) of the 64 strains belong to other serogroups (P < 0.001). The majority of bacteremic O2, O4, O6 and O83 E. coli strains were Hly+CNF1+ and expressed P-fimbriae or MRHA type III, whereas the strains of serogroup O18 were Hly+CNF1- and had P-fimbriae or MRHA type III, whereas the strains of serogroup O18 were Hly+CNF1- and had P-fimbriae. We conclude that strains from urosepsis show more virulence factors than bacteremic strains isolated from non-urosepsis.

Adolescent↗

PubMed1993

Quinolone action in Escherichia coli cells carrying gyrA and gyrB mutations.

We have isolated spontaneous mutant strains of Escherichia coli KL16 showing different levels of nalidixic acid (NAL) resistance. From 40 independent mutants, 36 had gyrA and four had gyrB mutations. Most of the gyrA mutations (30/36) conferred high level NAL resistance. In contrast, the only gyrB mutation that conferred a relatively high level of NAL resistance also determined enhanced susceptibility to quinolones with a piperazinyl substituent at C7 position of the quinolone ring (amphoteric quinolones). This gyrB mutation (denoted gyrB1604), jointly with a gyrA mutation (denoted gyrA972) which confers a high level of quinolone resistance, were used to construct strain IC2476, carrying the two gyr mutant alleles. The susceptibility of this strain to amphoteric quinolones (pipemidic acid, norfloxacin and ciprofloxacin) was similar to that of the gyrA972 single mutant. This result indicates that the change in GyrA subunit which determines a high level of quinolone-resistance has the capacity to mask the hypersusceptibility to amphoteric quinolones promoted by the GyrB1604 mutant subunit. This capacity was further confirmed by studying the effects of ciprofloxacin (CFX) on gyrase inhibition in the gyrA972 gyrB1604 strain.

Anti-Infective Agents↗

PubMed1993

Spectrophotometric analysis of a pharmaceutical preparation by principal component regression.

The use of a principal component regression procedure for quantitative analytical control of pharmaceutical preparations was investigated. The procedure was applied to the simultaneous quantitation of the active compound and preservative of a syrup by resolving their respective UV spectra. The most suitable conditions for quantitation were established and the results were compared with those obtained by HPLC.

Benzamides↗

PubMed1993

Serotypes and colonization factors of enterotoxigenic Escherichia coli isolated in various countries.

One hundred and six enterotoxigenic E. coli (ETEC) isolated from many geographical areas were serotyped and investigated for the presence of colonization factor antigens CFA/I and CFA/II, the expression of mannose-resistant haemagglutination (MRHA) and the levels of surface hydrophobicity. CFA/I was found in 6 (17%) of 36 LT+STa+ strains and in 15 (54%) of 28 STa+ strains; CFA/II was found in 16 (44%) of 36 LT+STa+ strains. None of 42 LT+ strains showed CFA/I or CFA/II. CFA/I was found in ETEC of serotypes O63:K-:H-, O78:K80, O128:K67 and O153:K:H45, whereas CFA/II was found in serotypes O6:H-, O6:K15:H16 and O6:K?:H40. Of the 69 CFA/I- CFA/II- ETEC strains, 9 (13%) showed MRHA with some of the seven erythrocyte species used and 21 (30%) were hydrophobic. Among the 21 hydrophobic strains CFA-negative we have detected: (i) 6 LT+ strains of serogroup O25 negative for MRHA, (ii) 5 strains O159 (4 LT+ and 1 LT+ STa+) also negative for MRHA, and (iii) 3 STa+ strains of serotype O27:K-:H7 that haemagglutinated calf and sheep erythrocytes when grown on Minca-Is. The 106 ETEC strains belonged to 20 different O serogroups. However, 77 (73%) were of one of nine serogroups (O6, O8, O25, O27, O78, O148, O153, O159 and O167). E. coli strains belonging to O6 and O153 groups predominated among ETEC isolated in Spain, O159 strains in the Central African Republic, O25 and O148 strains in Japan, and O15 and O78 strains in India.

Adult↗

PubMed1993

Mutability by polycyclic hydrocarbons is improved in derivatives of Escherichia coli WP2 uvrA with increased permeability.

Escherichia coli B, unlike both E. coli K12 and Salmonella typhimurium, is sensitive to the rough-specific phage C21. This sensitivity is probably due to the incomplete lipopolysaccharide core of the E. coli B cells, which confers on them a partial permeability to large molecules. Derivatives of WP2 uvrA, a tryptophan-requiring E. coli B strain, were rendered still more permeable by selecting for C21-resistant clones. The new permeable strains, when tested for mutagenesis induced by polycyclic hydrocarbons, showed a mutagenic response higher than that of the parental strains.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1993

Haemolytic Escherichia coli strains isolated from stools of healthy cats produce cytotoxic necrotizing factor type 1 (CNF1).

A total of 159 Escherichia coli colonies isolated from the stools of 23 healthy cats were studied for production of alpha-haemolysin (Hly), enterohaemolysin (EntHly), cytotoxic necrotizing factors (CNF1 and CNF2), verotoxins (VT) and heat-labile enterotoxin (LT). Hly+CNF1+, Hly+CNF2+, Hly+VT+ and Hly+ E. coli colonies were isolated from 12 (48%), 1 (4%), 1 (4%) and 2 (8%) respectively of the cats sampled. None of the 159 E. coli colonies produced LT or EntHly. Nine of 12 Hly+CNF1+ strains from the cats belonged to serogroup O6 and eleven to serotypes (O4:K?:H5 or H-, O6:K13:H1, O6:K53:H-, O6:K53:H1, O6:K53:H7 and O6:K14:H31) found among Hly+CNF1+ E. coli that cause urinary tract infections and sepsis in humans. Furthermore, 10 Hly+CNF1+ strains from the cats expressed the mannose-resistant haemagglutination (MRHA) type III. By contrast, the majority of nontoxigenic E. coli strains were MRHA negative and belonged to different O groups. We conclude that cats are a important reservoir of Hly+CNF1+ E. coli strains that possess similar characteristics to strains that can cause extraintestinal infections in humans and that Hly+ E. coli from cats usually do not produce shiga-like toxins with cytotoxic activity on Vero cells.

Animals↗

PubMed1993

Local and systemic immune responses in murine Helicobacter felis active chronic gastritis.

Helicobacter felis inoculated per os into germfree mice and their conventional non-germfree counterparts caused a persistent chronic gastritis of approximately 1 year in duration. Mononuclear leukocytes were the predominant inflammatory cell throughout the study, although polymorphonuclear cell infiltrates were detected as well. Immunohistochemical analyses of gastric mucosa from H. felis-infected mice revealed the presence of mucosal B220+ cells coalescing into lymphoid follicles surrounded by aggregates of Thy-1.2+ T cells; CD4+, CD5+, and alpha beta T cells predominated in organized gastric mucosal and submucosal lymphoid tissue, and CD11b+ cells occurred frequently in the mucosa. Follicular B cells comprised immunoglobulin M+ (IgM+) and IgA+ cells. Numerous IgA-producing B cells were present in the gastric glands, the lamina propria, and gastric epithelium. Infected animals developed anti-H. felis serum IgM antibody responses up to 8 weeks postinfection and significant levels of IgG anti-H. felis antibody in serum, which remained elevated throughout the 50-week course of the study.

Animals↗

PubMed1993

Reactogenicity and immunogenicity of a high-titer rhesus rotavirus-based quadrivalent rotavirus vaccine.

We evaluated the reactogenicity and antigenicity of a quadrivalent rotavirus vaccine composed of serotype 3 rhesus rotavirus (RRV) and three single-gene-substitution reassortants of RRV and human strain D (D x RRV, serotype 1), DS1 (DS1 x RRV, serotype 2), or ST3 (ST3 x RRV, serotype 4) in a double-masked study with 302 infants in Caracas, Venezuela. Three doses of the quadrivalent vaccine composed of either 10(5) PFU (low titer) or 10(6) PFU (high titer) of each component were administered to 99 and 101 infants, respectively, at 4-week intervals starting at the second month of age; 102 infants received a placebo. Postvaccination reactions were monitored by home visits every other day during the week postvaccination. The vaccine was associated with the occurrence of mild, short-lived febrile episodes in 26 and 23% of the recipients after the first doses of high- or low-titer vaccine, respectively, in comparison with 13% of the infants receiving the placebo. Febrile reactions occurred less frequently in vaccinees after the second or third dose than after the initial dose. The vaccine was not significantly associated with diarrhea or any additional symptom or sign. Serum specimens obtained shortly before the first, 4 weeks after the first, and 4 weeks after the third dose of vaccine or placebo were tested by an immunoglobulin A enzyme-linked immunosorbent assay and by neutralization assays. Seroresponses occurred significantly more often after 3 doses than after a single dose of either vaccine. Immunoglobulin A responses were observed in 80 and 79% of the infants after 3 doses of high- or low-titer vaccine, respectively. Most of the infants tested developed a neutralization response to RRV after 3 doses of the high- (90%) or low-(88%) titer vaccine. Neutralization response rates to human rotavirus serotypes 1 to 4 after 3 doses were similar in both vaccine and 87 of 90 receiving the high-titer vaccine developed seroresponses, as detected by any of the assays employed. The study indicates that 3 doses of quadrivalent vaccine at a titer of 10(6) PFU of each component offered no advantage over the lower-titer preparation for use in efficacy trials.

Antibodies, Viral↗

PubMed1993

[Enterotoxigenic Escherichia coli K99+, serotype 08:K25, produce cytotoxic necrotizing factor CNF1 and alpha-hemolysin].

A total of 54 K99+ and/or F41+ Escherichia coli strains isolated of calves and piglets with diarrhoea in different countries were investigated for production of heat-labile (LT) and heat-stable (STa) enterotoxins, verotoxins (VT1 and VT2), cytotoxic necrotizing factors (CNF1 and CNF2), alpha-haemolysin (Hly) and enterohaemolysin (EntHly). Fifty-one (94%) strains were STa+, two (4%) were STa+CNF1+Hly+ and one (2%) was not toxigenic. The two STa+CNF1+Hly+ E. coli strains expressed the K99 intestinal colonization factor and belonged to serotype O8:K25. The majority of STa-producing E. coli were K99+ and F41+ and belonged to serotypes O9:K(A)35, O101:K(A)28 and O101:K(A)30. All enterotoxigenic strains assayed in this study were negative for expression of the Att25, Vir and B23 adhesins recently detected in E. coli that cause infections in calves.

Adhesins, Escherichia coli↗