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Biomedical subjects

G Oliver

Publications and source records attributed to G Oliver.

At least 55 records · Page 3Linked to original sources
PubMed1999

Hydrolytic action of Lactobacillus casei CRL 705 on pork muscle sarcoplasmic and myofibrillar proteins.

Lactobacillus casei CRL 705 was screened, among other meat isolates, for its proteinase and aminopeptidase activities toward synthetic substrates and, according to that, selected for specific assays on muscle proteins. The hydrolytic effects of whole cells, cell free extracts (CFE), and the combination of both on muscle sarcoplasmic and myofibrillar protein extracts was evaluated by SDS-PAGE and reverse phase HPLC analyses. The proteinase activity of whole cells caused the degradation of a great number of sarcoplasmic protein bands. A partial hydrolysis was also associated with CFE that when combined with whole cells showed an important additional degradation. Peptide profiles from sarcoplasmic protein extracts were greatly modified regardless of the addition of whole cells or CFE, although their combination intensified these changes. The generation of free amino acids was remarkable when whole cells and CFE were incorporated together to sarcoplasmic protein extracts.

Aminopeptidases↗
PubMed1999

Prox1 function is crucial for mouse lens-fibre elongation.

Although insights have emerged regarding genes controlling the early stages of eye formation, little is known about lens-fibre differentiation and elongation. The expression pattern of the Prox1 homeobox gene suggests it has a role in a variety of embryonic tissues, including lens. To analyse the requirement for Prox1 during mammalian development, we inactivated the locus in mice. Homozygous Prox1-null mice die at mid-gestation from multiple developmental defects; here we describe the specific effect on lens development. Prox1 inactivation causes abnormal cellular proliferation, downregulated expression of the cell-cycle inhibitors Cdkn1b (also known as p27KIP1) and Cdkn1c (also known as p57KIP2), misexpression of E-cadherin and inappropriate apoptosis. Consequently, mutant lens cells fail to polarize and elongate properly, resulting in a hollow lens. Our data provide evidence that the progression of terminal fibre differentiation and elongation is dependent on Prox1 activity during lens development.

Animals↗
PubMed1999

Hydrolysis of pork muscle sarcoplasmic proteins by lactobacillus curvatus and lactobacillus sake.

Lactobacillus curvatus CECT 904 and Lactobacillus sake CECT 4808 were selected on the basis of their proteolytic activities against synthetic substrates. Further, the effects of whole cells, cell extracts, and a combination of both enzymatic sources on muscle sarcoplasmic proteins were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and reverse-phase high-performance liquid chromatography analyses. Strains of both species displayed proteinase activities on five sarcoplasmic proteins. The inoculation of whole cells caused a degradation of peptides, whereas the addition of cell extracts resulted in the generation of both hydrophilic and hydrophobic peptides. This phenomenon was remarkably more pronounced when L. curvatus was involved. Whole cells also consumed a great amount of free amino acids, while the addition of intracellular enzymes contributed to their generation. L. sake accounted for a greater release of free amino acids. In general, cell viability and also proteolytic events were promoted when cell suspensions were provided with cell extracts as an extra source of enzymes.

Journal Article↗
PubMed1999

Characterization of muscle sarcoplasmic and myofibrillar protein hydrolysis caused by Lactobacillus plantarum.

Strains of Lactobacillus plantarum originally isolated from sausages were screened for proteinase and aminopeptidase activities toward synthetic substrates; on the basis of that screening, L. plantarum CRL 681 was selected for further assays on muscle proteins. The activities of whole cells, cell extracts (CE), and a combination of both on sarcoplasmic and myofibrillar protein extracts were determined by protein, peptide, and free-amino-acid analyses. Proteinase from whole cells initiated the hydrolysis of sarcoplasmic proteins. The addition of CE intensified the proteolysis. Whole cells generated hydrophilic peptides from both sarcoplasmic and myofibrillar proteins. Other peptides of a hydrophobic nature resulted from the combination of whole cells and CE. The action of both enzymatic sources on myofibrillar proteins caused maximal increases in lysine, arginine, and leucine, while the action of those on sarcoplasmic proteins mainly released alanine. In general, pronounced hydrolysis of muscle proteins required enzyme activities from whole cells in addition to those supplied by CE.

Amino Acids↗
PubMed1999

Some probiotic properties of chicken lactobacilli.

The beneficial effect of lactobacilli has been attributed to their ability to colonize human and animal gastrointestinal tracts. In this work, adhesion assays with three lactobacillus strains and intestinal fragments obtained from chickens were assessed. Lactobacillus animalis and L. fermentum were able to adhere to three kinds of epithelial cells (crop, small and large intestines) with predominance to small intestine. Among the strains considered, L. fermentum subsp. cellobiosus showed the lowest and L. animalis the highest adhesion ability. Scanning electron microphotographs showing L. animalis and L. fermentum adhering to intestinal cells were obtained. The characterization of L. animalis adhesion indicated that lectin-like structure of this strain has glucose/mannose as specific sugars of binding. However, a calcium requirement was not observed. The adhesion of L. fermentum was reduced by addition of sialic acid or mannose (P < 0.01). These carbohydrates can be involved in the interaction between adhesin and epithelial surface. In this case, the dependence on bivalent cations was demonstrated. Lactobacillus fermentum was effective in reducing the attachment of Salmonella pullorum by 77%, while L. animalis was able to inhibit (90%, 88%, and 78%) the adhesion of S. pullorum, S. enteritidis, and S. gallinarum to host-specific epithelial fragments respectively. Our results from this in vitro model suggest that these lactobacilli are able to block the binding sites for Salmonella adhesion.

Animals↗
PubMed1999

Lectin-like protein fractions in lactic acid bacteria isolated from chickens.

Agglutination of fifty bacterial strains isolated from gastric-intestinal tract of chickens with yeasts treated with glutaraldehyde and glycine was assayed to study possible adhesion mechanisms to epithelia. It was found that Lactobacillus fermentum, Lactobacillus fermentum subsp. cellobiosus and Lactobacillus animalis agglutinated yeasts massively and this agglutination was inhibited in each strain by different representative sugars: agglutination was inhibited in three selected strains with 0.2 M mannose. The three strains agglutinated chicken red blood cells, but did not agglutinate human red blood cells, whereas the agglutinating capacity for other animal erythrocytes was variable. The lectins were partially purified on a Sephadex G-75 column and affinity chromatography. The molecular weight of each of the protein subunits was estimated as about 50-67 kDa using electrophoretic techniques. After treatment with lipase and metaperiodate modifications bacterial superficies and/or liberation of some structures produced an unspecific interaction with increase in the yeast agglutination and hemagglutination. The optimal conditions of work were: pH 6-7, Ca2+ 1 mM, Mg2+ 2 mM and 37-42 degrees C.

Agglutination↗
PubMed1999

Study of adhesion of Lactobacillus casei CRL 431 to ileal intestinal cells of mice.

It is well known that the cell wall of Lactobacillus casei CRL 431, a strain present in probiotics, presents lectinlike surface molecules. Presence of these molecules stimulates the immune system. Given the role that lectins and lectinlike substances play in the adhesion phenomenon, it is probable that this is an initial stage in the immunostimulation produced by this bacterium. To confirm this, adhesion of this microorganism to exfoliated mouse ileal epithelial cells was studied in vitro. Other L. casei strains isolated from adult human intestines and one of dairy origin were also examined for their ability to adhere to ileal epithelial cells. Another strain, which was included in the present study, was Lactobacillus acidophilus CRL 730. L. casei strains isolated from humans showed good ability to adhere to ileal epithelial cells, whereas L. casei isolated from dairy origin did not. Adhesion was only observed at 37 degrees C and at a pH between 6 and 7.5. The exposure time needed for highest adhesion was 30 min. Presence of lectinlike substances on the surface of L. casei CRL 431 is important to this adhesion phenomenon, since adherence capacity was lost after removal of these substances.

Animals↗
PubMed1999

Lactobacilli isolated from chicken intestines: potential use as probiotics.

Lactobacillus strains were tested for their in vitro probiotic properties. Cell surface hydrophobicity was found to be very high for Lactobacillus fermentum subsp. cellobiosus and Salmonella Gallinarum; high values could indicate a greater ability to adhere to epithelial cells. Studies on Lactobacillus animalis indicated relative cell surface hydrophobicities smaller than those of L. fermentum subsp. cellobiosus and L. fermentum. L. animalis and Enterococcus faecalis were able to coaggregate with L. fermentum subsp. cellobiosus and L. fermentum, respectively, but not with Salmonella Gallinarum. After mixed-culture studies for determining suitable growth behavior, the pair of strains L. animalis plus L. fermentum subsp. cellobiosus was selected for an attempted challenge against Salmonella Gallinarum. Double and triple mixed-culture studies indicated that selected lactobacillus strains were able to retain their beneficial characteristics in the presence of Salmonella Gallinarum such as presence of lectins, production of antimicrobial compounds, and ability to grow and compete. The selected microorganisms can be considered as potential ingredients for a chicken probiotic feed formulation intended to control salmonellosis and also improve poultry sanitation.

Animals↗
PubMed1999

Antagonistic effect of Enterococcus faecium J96 against human and poultry pathogenic Salmonella spp.

Production of antagonistic compounds was studied in a strain of Enterococcus faecium isolated from the intestinal tract of a free-ranging chicken. Production of lactic acid and a bacteriocin was observed in cultures of this bacterium, alone and in mixed culture fermentations with pathogenic Salmonella serotypes (i.e., Gallinarum, Pullorum, Enteritidis, and Typhimurium). Growth inhibition of these avian and human pathogens was observed after 4 h of incubation at 37 degrees C in CAm broth, a medium developed according to the nutrients present in chicken food. The antibacterial action was due to the combined effect of lactic acid and bacteriocin. Accumulation of these metabolites caused both a bacteriostatic and a bactericidal action against the gram-negative bacteria assayed.

Animals↗
PubMed1999

Starter culture activity in refrigerated fermented soymilk.

The refrigerated shelf life of soymilk fermented with single cultures of Lactobacillus fermentum, L. casei, Streptococcus salivarius subsp. thermophilus, and Bifidobacterium longum was evaluated. During storage at 4 degrees C for 28 days, the stability of the microflora differed markedly among the starter cultures. After 28 days, the average numbers of S. salivarius subsp. thermophilus decreased by two log cycles to 6.0 x 10(7) CFU/ml, whereas those of L. casei increased gradually by more than two log cycles to 4.6 x 10(9) CFU/ml. Numbers of B. longum and L. fermentum remained moderately high (8.7 x 10(8) CFU/ml and 3.7 x 10(8) CFU/ml, respectively) even after 28 days of storage. S. salivarius subsp. thermophilus and L. casei continued to metabolize sucrose during the storage period, but the pattern of consumption was different among the strains. The other starter cultures did not seem to have significant activity (P > 0.05) on the residual sugars. In most cases, L(+)-lactate predominated.

Animals↗
PubMed1998

Tuberculosis notifications in Australia, 1996. Communicable Diseases Network Australia New Zealand.

Since the implementation of the National Mycobacterial Surveillance System (NMSS) in 1991, the epidemiology and trends of tuberculosis in Australia have been described in a series of annual reports. This article presents an analysis of the data for tuberculosis notifications for 1996. A total of 1,037 notifications of tuberculosis were received for the year 1996, and the crude rates of new and relapsed disease were reported at 5.37 per 100,000 and 0.29 per 100,000 respectively. Rates of tuberculosis have remained stable over the last decade and the majority of notifications and highest rates of disease continue to occur in the overseas-born population.

Adolescent↗
PubMed1998

A longitudinal study of work load and variations in psychological well-being, cortisol, smoking, and alcohol consumption.

The effects of variations in work load (indexed by paid work hours) on psychological well-being, cortisol, smoking, and alcohol consumption were examined in a sample of 71 workers (44 women, 27 men) in the retail industry. Measures were obtained on four occasions over a six-month period, and assessments were ranked individually according to hours of work over the past seven days. Job strain (demand/control) and job social support were evaluated as potential moderators of responses. Paid work hours ranged from a mean of 32.6 to 48.0 hours per week, and ratings of work-home conflict and perceived stress varied across assessments. Salivary cortisol was inversely associated with job strain and did not vary across sessions. Female but not male smokers consumed more cigarettes during periods of long work hours, and self-reported smoking and cotinine concentrations were greater among smokers with higher nicotine dependency scores. Men but not women with poor social supports consumed more alcohol as work hours lengthened. These data indicate that health behaviors are affected only to a limited extent by variations in work load. Results are discussed in the context of adaptation to work and the pathways linking stressful experience with health risk.

Adult↗
PubMed1998

Weight-control practices of adults in a rural community.

Obesity is recognised as a significant public health problem, and health authorities are concerned with promoting a healthy weight for all adults. However, there is a paucity of data about community weight-control practices. We surveyed weight-control behaviour, strategies and goals in a population-based sample of 1342 adults living in rural Victoria. In addition to the 20 per cent of adults who were attempting to lose weight, 22 per cent were actively trying to maintain their present weight or to avoid weight gain. Those taking action for their weight most often did so for health-related reasons, and most of the strategies used were those recommended by health authorities. However, some adults, particularly women, adopted potentially unhealthy weight-control practices. One in four women whose weight was acceptable was trying to lose weight, and 14 per cent of women had a weight goal that was below the acceptable range. Conversely, 50 per cent of men had a weight goal higher than that currently considered acceptable. Additional research is required to assess more accurately the specific nature of community weight-control practices.

Adolescent↗
PubMed1998

Study of the morphology of the cell walls of some strains of lactic acid bacteria and related species.

The objective of the present study was to find an explanation for the biological effect of the bacteria present in a biotherapeutic milk (Lactobacillus casei CRL 431 and Lactobacillus acidophilus CRL 730). The ability of bacterial cell walls to induce an immune response when introduced into an organism is well known. In this paper we specifically analyzed the morphology of these cell walls. Besides the two bacterial strains used in the fermented milk, two other lactic acid bacteria, belonging to another genus and unable to induce an immune system response, as well as a strain of Propionibacterium, of which the immune modulating capacity is known, were used in this work. We found a structural particularly in strains with immunostimulating capacity (L. casei CRL 431 and P. acidopropionici CRL 1198): molecules which protrude from the cell surface. In L. casei CRL 431 these molecules were identified as lectins because they are able to agglutinate yeast cells treated with glutaraldehyde and glycine. The structures protruding from P. acidipropionici CRL 1198 cells were teichoic acids. Teichoic acid and lectin-like structures can participate in adhesion to intestinal cells. The immunostimulation observed can be induced by the adhesion phenomenon.

Adjuvants, Immunologic↗
PubMed1997

A population-based study determining the incidence of tuberculosis attributable to HIV infection.

Although the tuberculosis (TB) epidemic has been attributed in part to the AIDS epidemic, few studies in the United States have measured the risk attributable to HIV infection. We linked the TB registry of Alameda County, California, 1985 to 1994, with the AIDS registry, 1982 to 1994. We defined a person with TB and HIV infection as a patient in the TB registry with the same name, race/ethnicity, gender, and date of birth as a patient in the AIDS registry. We used population and HIV seroprevalence estimates to determine the HIV-seropositive and -seronegative population at risk of TB in 1994. Of 1990 TB cases reported by Alameda County from 1985 to 1994, 116 (5.8%) had an AIDS diagnosis. Among 25- to 44-year-old TB patients, 25.2% of U.S.-born men and 8.4% of U.S.-born women had an AIDS diagnosis. In 1994, the estimated TB incidence rate in persons with HIV infection was 198.1 per 100,000 versus a rate of 13.9 of 100,000 among persons without HIV infection (rate ratio, 13.8; 95% confidence interval, 8.0, 23.8). In 1994, 93% of TB cases among HIV seropositive persons, 6.4% of all TB cases, and 16.7% of TB cases aged 25 to 44 years were attributable to HIV infection. The high attributable risk underscores the impact of HIV on the TB epidemic. All persons with HIV infection should be screened for TB, and persons with TB infection should be screened for HIV infection. TB/HIV coinfected patients should be provided with TB preventive therapy.

Adult↗
PubMed1997

Australia's notifiable diseases status, 1996. Annual report of the National Notifiable Diseases Surveillance System.

In 1996 there were 65,024 notifications to the National Notifiable Diseases Surveillance System. The record high number of Ross River virus infection notifications was of particular note. The highest rates were recorded in Western Australia, where an outbreak was documented in the South West, and in Queensland. Most cases occurred in the late summer and early autumn months. The number of measles cases has continued to fall markedly following the outbreak in 1993 and 1994. Rubella notifications also fell in 1996. The number of cases of pertussis remained at a similar level to that recorded in recent years, the highest notification rate being recorded for children under the age of one year. A peak in late 1996 marked a resurgence in the pertussis epidemic which has continued into 1997. Notifications of Haemophilus influenzae type b continued to decline reaching a record low rate of 0.3 notifications per 100,000 population. For the enteric diseases, the number of cases of campylobacteriosis rose, with an annual adjusted notification rate of 100.4 per 100,000 population; more notifications were received for this disease than for any other in 1996. The number of hepatitis A cases also rose relative to 1995. This is a reversal of the trend observed in recent years when the notification rate fell. The number of cases of salmonellosis and shigellosis remained stable. Notifications for chlamydial infection and gonococcal infection rose relative to 1995, whilst those for syphilis fell.

Alphavirus Infections↗