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O Porras

Publications and source records attributed to O Porras.

30 records · Page 2Linked to original sources
PubMed1986

Application of multilocus enzyme gel electrophoresis to Haemophilus influenzae.

Multilocus enzyme electrophoresis was adapted to the study of Haemophilus influenzae. Protein extracts from sonicated whole bacteria were subjected to starch gel electrophoresis. After staining with substrates, the position of each isoenzyme (electromorph) was registered. Each isolate was assigned an electrophoretic type (ET) by the combination of electromorphs for the enzymes stained. Twenty-seven enzymes were tested; 12 were expressed in H. influenzae. Six enzymes were selected for subsequent study: malate dehydrogenase (MDH), phenylalanylleucine peptidase (PE2), 6-phosphogluconate dehydrogenase (6PG), adenylate kinase (AK), glucose 6-phosphate dehydrogenase (G6P), and phosphoglucose isomerase (PGI). They were polymorphic and occurred in all isolates. Six electromorphs were found for PE2, G6P, and PGI, five for MDH, four for 6PG, and three for AK. PE2, G6P, and PGI contributed most of the ET resolution (48 of 49 ETs). Multilocus enzyme electrophoresis showed several advantages over previous typing techniques. An ET could be assigned to both typable and nontypable (NT) isolates. The technique was powerful in resolving differences among isolates. The 94 isolates comprised 49 ETs, five biotypes, and six capsular types and NT isolates. Strains known to be related expressed the same ET, e.g., RAB b+ and b-, ET12; Ma a+ and a-, ET1. ET variability among type b isolates was low; 26 of 28 clinical isolates expressed ET14; 2 of 28 expressed ET13 and ET15, differing from ET14 by one electromorph each. In contrast, the 47 NT isolates comprised 38 different ETs. No ETs were shared between non-type b capsulated strains and type b or NT strains. Interestingly, five NT isolates expressed the same ET as type b strains. (iv) Strains of the same capsular type but different biotypes expressed different ETs. ET determinations will thus be useful in studying the epidemiology and evolution of H. influenzae.

Bacterial Proteins↗
PubMed1986

Difference in structure between type b and nontypable Haemophilus influenzae populations.

The extent of chromosomal genetic variability and the genetic structure of Haemophilus influenzae populations was analyzed. A total of 119 isolates from humans in Göteborg, Sweden, and Birmingham, Ala., and 16 strains from a type culture collection were characterized for capsular type, biotype, outer membrane protein profile, and enzyme electrophoretic type (ET). The results of this study indicate that the bacteria identified as H. influenzae are a genetically extremely variable array of organisms. For the six enzymes studied, the estimated mean genetic diversity was 0.57 (approximately 20% higher than the corresponding estimate for Escherichia coli). Two lines of evidence indicate that despite its ability to recombine by transformation, H. influenzae maintains a largely clonal population structure. Although there is considerable potential for generating different genotypes, there were only 88 distinct ETs among the 135 strains, and isolates of the same ET and biotype were recovered at frequencies greater than would be anticipated at random. This evidence for a clonal population structure holds for uncapsulated as well as capsulated strains. However, these data also suggest that the stability of H. influenzae clones (clone persistence time) may be less than that of the nontransforming species E. coli. The ET data indicate that there is somewhat less variability among H. influenzae strains that express the same capsular antigens, biotype, and outer membrane proteins than among randomly chosen isolates. Nevertheless, there is substantial genetic variation among isolates within each of these classes and combinations thereof. There is also variation in these typing characteristics among strains of the same ET. These observations and those on genetic variability and population structures have implications for the characterization of H. influenzae isolates in clinical and epidemiological studies.

Bacterial Outer Membrane Proteins↗
PubMed1985

Defence of mucous membranes by antibodies, receptor analogues and non-specific host factors.

Most infections reach man via the mucosal membranes, and more than half of the lymphoid system is found in connection with mucosae. The major antibodies found on mucous membranes are secretory IgA, which function primarily by binding microorganisms and thereby preventing their contact with the host tissues. The optimal mode of immunization to obtain a secretory IgA response is not well defined. Repeated mucosal exposure with antigen may result in oral tolerance, with decreasing circulating antibodies but a remaining secretory IgA response. The secretory IgA response is usually short-lived and can be difficult to boost. IgM as well as IgG antibodies may add to host defence at the mucosal level, but when engaged, they usually induce inflammation in host tissues. Analogues to bacterial receptors on mucosal epithelium may be present in exocrine secretions such as human milk. During an attack on the host, it is possible that such receptor analogues may aid in the prevention of attachment of bacteria to mucous membranes used as an initial site. A number of non-specific host factors support mucosal defence. One of them is lactoferrin. Lactoferrin deficiency seems to result in recurrent bacterial infections, suggesting its importance in normal host defence.

Antibody Formation↗
PubMed1985

Method for testing adherence of Haemophilus influenzae to human buccal epithelial cells.

A method for testing adherence of Haemophilus influenzae strains to buccal mucosal cells is described. Bacteria grown in broth for 4 h were mixed with buccal mucosal cells. After elimination of unattached bacteria by repeated cycles of centrifugation and resuspension in PBS, the number of attached bacteria was counted microscopically. Optimal results were obtained with an early log-phase bacterial culture at a concentration of 10(9) bacteria/ml mixed with 2 X 10(4) cells/ml and incubated at 37 degrees C for 60 min. This assay showed an at least ten times higher rate of adherence for Haemophilus influenzae than previous studies. Nontypeable strains attached in higher numbers than strains with the type b capsule. Adherence was related to the frequency of nontypeable strains rather than to the site of isolation or type of infection. Thus all the isolates from middle ear fluid were nontypeable, and all but one adhered. The results suggest a difference in virulence mechanisms between type b and nontypeable Haemophilus influenzae strains.

Adhesiveness↗
PubMed1985

Detection of soy protein in soy lecithin, margarine and, occasionally, soy oil.

Samples of soy lecithin, soy oil and margarine were tested for the presence of soy proteins by an inhibition technique using ELISA. All but one of the soy lecithin samples contained soy protein, as did some of the soy oil and margarine samples. The positive margarines contained only about 25% as much soy protein as the soy lecithin preparations. The presence of soy proteins in these soy products might account for hitherto unrecognized exposure to soy proteins in various foods.

Animals↗
PubMed1985

Protective factors in milk and the development of the immune system.

The neonate is immature in certain immunologic functions. The slow development of secretory immunoglobin A (IgA) seems to be compensated by selective transfer of secretory IgM into exocrine secretions on mucous membranes during the first few months of life. Secretory IgA and secretory IgM antibodies against Escherichia coli and poliovirus are already found in the neonate, possibly in response to the maternal anti-idiotypic IgG antibodies transplacentally exposing the fetus. Via such a mechanism, food antibodies could occur before direct food exposure in the infant. Human milk provides large amounts of antibodies (as a crude comparison, about 50 times the amount of antibodies given to a patient with hypogammaglobulinemia). The milk antibodies, dominated by secretory IgA, protect especially against intestinal infections. The milk also contains oligosaccharide analogues to epithelial receptors for bacteria. They, as well as a number of milk components such as lactoferrin and lysozyme, may contribute to host defense. The food antibodies in human milk may influence the infant's immune response to foreign food proteins introduced during weaning.

Animals↗
PubMed1984

The immune response of the mammary gland and its significance for the neonate.

The immune response of the mammary gland is dominated by local production of secretory IgA antibodies (SIgA). These milk antibodies, amounting to about 0.5-1 g/day throughout lactation, are directed against food proteins and microorganisms often present in the intestine. This is presumably explained by the enteromammaric link: after antigenic exposure in the Peyer's patches of lymphoid cells they home to various exocrine glands, including the mammary gland. Similarly, lymphoid cells from the bronchial mucosa, may contribute to the antibody-producing cell population in the mammary gland. SIgA antibodies against common foods like cow's milk and soy proteins are regularly found in milk if such proteins are part of the mother's diet. It is possible, but unproven, that milk antibodies can decrease the exposure of the infant's intestinal mucosa to foreign food proteins introduced during continued breast-feeding. Milk SIgA antibodies do not prevent intestinal colonization by microorganisms, against which the milk antibodies are directed. The SIgA antibodies are thought to exert protection primarily by preventing contact between the microorganisms and the mucosal membranes. In this manner, human milk blocks attachment of otitis media-causing strains of pneumococci and H. influenzae to retropharyngeal cells, possibly explaining why breast-feeding may prevent otitis media. Milk antibodies have anti-attachment capacity, but there is also low molecular weight material in the milk with this capacity. It probably consists of analogues to the oligosaccharide receptor for pneumococci on the retropharyngeal cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

Food and immunological development.

The infant's host defence is deficient in IgA for mucosal protection and also in IgG2 for protection against encapsulated bacteria. The baby is provided with about one gram a day of milk secretory IgA antibodies against most intestinal microorganisms and also food proteins. These milk antibodies together with a number of other defence factors in the milk protect the baby against gastrointestinal and respiratory infections. Maternal undernutrition does not necessarily diminish the milk IgA concentration or 24 hour output. The infant seems to be low in secretory IgA antibodies for several months as studied in saliva. It is of great importance to protect mucosal membranes especially the intestinal mucosa, so that its nutrient uptake is not disturbed. Infections in infancy especially in the gastrointestinal tract is an important cause of undernutrition. The human milk antibodies against cow's milk and soy protein may decrease the exposure to these food proteins during weaning and possibly decrease the risk of developing allergy. Soy oil can contain soy protein, which may explain some food intolerance reactions.

Animals↗
PubMedDate not supplied

Defence of mucous membranes by antibodies, receptor analogues and non-specific host factors.

Most infections reach man via the mucosal membranes, and more than half of the lymphoid system is found in connection with mucosae. The major antibodies found on mucous membranes are secretory IgA, which function primarily by binding microorganisms and thereby preventing their contact with the host tissues. The optimal mode of immunization to obtain a secretory IgA response is not well defined. Repeated mucosal exposure with antigen may result in oral tolerance, with decreasing circulating antibodies but a remaining secretory IgA response. The secretory IgA response is usually short-lived and can be difficult to boost. IgM as well as IgG antibodies may add to host defence at the mucosal level, but when engaged, they usually induce inflammation in host tissues. Analogues to bacterial receptors on mucosal epithelium may be present in exocrine secretions such as human milk. During an attack on the host, it is possible that such receptor analogues may aid in the prevention of attachment of bacteria to mucous membranes used as an initial site. A number of non-specific host factors support mucosal defence. One of them is lactoferrin. Lactoferrin deficiency seems to result in recurrent bacterial infections, suggesting its importance in normal host defence.

Administration, Oral↗
PubMedDate not supplied

The secretory IgA system.

The secretory IgA system is common to all mucosal membranes and is presumably of great importance for their defense. In addition to the secretory IgA antibodies produced in a mucosa in response to a local antigenic stimulus there is a spread of this type of IgA response via committed lymphocytes. They originate from central lymphoid organs in the intestinal (Peyer's patches) and bronchial mucosa (bronchus-associated lymphoid tissue, BALT) which they leave after antigenic exposure. They migrate, or "home", to exocrine glands such as the lacrimal, salivary, mammary and prostatic glands and mucosal membranes of the respiratory, gastrointestinal and genito-urinary tract. Almost half of all lymphocytes may be involved in the production of IgA antibodies. The secretory IgA antibodies are the dominating immunoglobulins in exocrine secretions on mucous membranes. They function primarily by preventing contact between the microbe and the host tissue most commonly attacked in infections, the mucous membrane. The fact that breast-feeding protects the infant against intestinal infections is one good example of the clinical significance of secretory IgA antibodies. This mode of protection can be enhanced by vaccination.

Breast Feeding↗
PubMedDate not supplied

Juvenile chronic arthritis in Costa Rica. A pilot referral study.

In order to adequately care for patients with chronic disorders and to properly allocate resources, the epidemiology of the underlying disease must be know. Proper population based studies involve substantial planning and educational programs, however. To prepare for such a study of pediatric rheumatic disorders, we performed a referral-based pilot study. During an eleven-month period pediatricians all over Costa Rica were asked to refer to us all new cases of possible rheumatic disorders among children less than 16 years of age, using the EULAR criteria for juvenile chronic arthritis. The children were evaluated at the National Children's Hospital. An annual incidence of 5.9 cases of all types of pediatric rheumatic diseases per 100,000 was found. Incidences of 5.4 per 100,000 children below 16 years of age and 6.1 for children below 12 years of age were observed for juvenile chronic arthritis (JCA). 77% of the JCA cases were of pauciarticular onset, and 23% were of polyarticular onset. No cases of systemic JCA were diagnosed. The female to male ratio was 3:2. Antinuclear antibodies were positive in 13% of the JCA cases, and IgM rheumatoid factor was found in 15% of the children. Chronic iritis was noted in only 2 cases; both were girls and both were ANA positive. The incidence found was low compared to population-based studies, but in the same range as hospital-based investigations.

Adolescent↗