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PubMed2002

Inactivation of acid-adapted and nonadapted Escherichia coli O157:H7 during drying and storage of beef jerky treated with different marinades.

The inactivation of both acid-adapted and unadapted Escherichia coli O157:H7 during the processing of beef jerky was studied. Following inoculation with the pathogen, beef slices were subjected to different predrying marinade treatments, dried at 60 degrees C for 10 h, and stored at 25 degrees C for 60 d. The predrying treatments evaluated were as follows: (i) no treatment (C), (ii) traditional marinade (TM), (iii) double-strength TM modified with added 1.2% sodium lactate, 9% acetic acid, and 68% soy sauce with 5% ethanol (MM), (iv) dipping into 5% acetic acid for 10 min followed by application of TM (AATM), and (v) dipping into 1% Tween 20 for 15 min and then into 5% acetic acid for 10 min followed by TM (TWTM). Bacterial survivors were determined during drying and storage using tryptic soy agar with 0.1% pyruvate, modified eosin methylene blue agar, and sorbitol MacConkey agar. Results indicated that bacterial populations decreased during drying in the order of TWTM (4.9 to 6.7 log) > AATM > MM > C > or = TM (2.8 to 4.9 log) predrying treatments. Populations of acid-adapted E. coli O157:H7 decreased faster (P < 0.05) in AATM and TWTM than nonadapted cells during drying, whereas no significant difference was found in inactivation of acid-adapted and nonadapted inocula in C and TM samples. MM was more effective in inactivating the nonadapted than the adapted inoculum. Bacterial populations continued to decline during storage and dropped below the detection limit (-0.4 log10 CFU/cm2) as early as day 0 (after drying) or as late as day 60, depending on acid adaptation, predrying treatment, and agar medium. The results indicated that acid adaptation may not increase resistance to the hurdles involved in jerky processing and that use of additional antimicrobial chemicals or preservatives in jerky marination may improve the effectiveness of drying in inactivating E. coli O157:H7.

Acetic Acid↗
PubMedDate not supplied

Relative fitness can decrease in evolving asexual populations of S. cerevisiae.

It is generally accepted from the darwinian theory of evolution that a progressive increase in population adaptation will occur in populations containing genetic variation in fitness, until a stable equilibrium is reached and/or the additive genetic variation is exhausted. However, the theoretical literature of population genetics documents exceptions where mean population fitness may decrease in response to evolutionary changes in gene frequency, due to varying selective coefficients, sexual selection or to epistatic interactions between loci. Until now, no examples of such exceptions have been documented from fitness estimates in either natural or experimental populations. We present here direct evidence that, as a result of epistatic interactions between adaptive mutations, mean population fitness can decrease in asexual evolving populations of the yeast Saccharomyces cerevisiae.

Biological Evolution↗
PubMed2004

Antibacterial activity of plants used in cooking for aroma and taste.

Thirty-three plants used in cooking for aroma and taste were examined for antibacterial activity against pathogens causing foodborne infections. Vibrio parahaemolyticus and Staphylococcus aureus were sensitive to many kinds of plant extracts, whereas Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella Enteritidis populations decreased in only six, one, and three plant extracts, respectively. The polyphenol content in the plants was significantly different between the antibacterial plants and nonantibacterial plants, indicating that the polyphenols were related to the antibacterial action of these plants. Antibacterial activity of various concentrations of leaf extracts from Japanese persimmon, white cedar, and grape were investigated. Japanese persimmon and white cedar leaf extracts at low concentrations affected L. monocytogenes and V. parahaemolyticus rapidly. With grape leaf extract at low concentrations, the population of L. monocytogenes decreased similarly to Japanese persimmon and white cedar leaves. This study demonstrates that many plants used in cooking for aroma and taste contain polyphenols and exhibit antibacterial activity against foodborne pathogens.

Anti-Bacterial Agents↗
PubMed2003

The application potential of sintered beta-dicalcium pyrophosphate in total joint arthroplasty.

An in vitro bone cell culture model was used to evaluate the potential application of sintered beta-dicalcium pyrophosphate (SDCP) in arthroplasty surgery. Primary osteoclasts and osteoblasts were cocultured with different sizes of SDCP particles. The changes in cell counts and the synthesis and secretion of alkaline phosphatase, acid phosphatase, and prostaglandin E(2) in response to the SDCP particles were monitored. When bone cells were cultured with SDCP particles smaller than 53 microm, both the osteoblast and osteoclast cell counts decreased significantly. When the SDCP particles were larger than 177 microm, although the osteoblast population increased significantly, the osteoclast population decreased significantly. Simultaneously, the titer of prostaglandin E(2) in the medium and the cytoplasmic prostaglandin E(2) increased significantly. We concluded that SDCP is a potentially useful bioceramic for the prevention of osteoclast-mediated periprosthetic osteolysis.

Absorbable Implants↗
PubMed2003

[National surveillance of schistosomiasis from 2000 to 2002].

OBJECTIVE: To identify the trends of endemic situation at the twenty-one national surveillance sites from 2000 to 2002. METHODS: According to the protocol of the national surveillance system, longitudinal surveillance of endemic situation of schistosomiasis was carried out at the twenty-one surveillance sites since 2000. RESULTS: Relative indexes of endemic situation of schistosomiasis decreased in two surveillance sites annually. The infection rate of Schistosoma japonicum in human population decreased in most surveillance sites. The infection rate of cattle decreased in eight surveillance sites. However, acute cases were found in two sites each year. The density of live snails and infected snails was higher compared with that in 2000 among eight sites and infected snails were found in inner embankment in Junshan surveillance sites. Hunan Province, in 2002 at first time. The snail ridden areas increased significantly in Fengjin sites, Shanghai, where schistosomiasis was eliminated years ago. CONCLUSION: Current control strategies have some impact on the morbidity of schistosomiasis. However, these strategies should be lasted for longer time and surveillance on snails should be enhanced.

Adolescent↗
PubMed1987

Ruminal microbial development in conventionally or early-weaned calves.

Eight bull calves (four Holsteins and four Ayrshire calves with mean birth weight of 38.8 kg) were ruminally cannulated at 3 d of age and allocated to one of two weaning programs. All calves were fed colostrum for 3 d after birth and milk until weaning. Calves in the conventional-weaning program were fed a starter diet from 3 d of age and weaned at 6 wk of age. In the early-weaning program, calves were fed a highly palatable pre-starter diet from 3 d of age until they consumed 227 g/d, and then fed a mixture of pre-starter (227 g) and starter diet ad libitum. Calves in this group were weaned at 4 wk of age. Ruminal samples were collected at 3 and 7 d, then weekly thereafter through 8 wk and at 10 and 12 wk of age to assess microbial activity. Calves in the early-weaned group had a higher concentration of total ruminal volatile fatty acids at an earlier age than the calves in the conventional-weaning program. This was accompanied by a trend toward higher lactate concentrations and lower ruminal pH in the early-weaned group during their first 4 wk of age. Lactate and ammonia concentrations decreased with calf age. The total anaerobic bacterial counts increased slightly with calf age, whereas Streptococcus bovis and facultative bacterial populations decreased with calf age. Amylolytic, proteolytic, lactobacilli, lactate-utilizers, cellulolytic and methanogenic bacterial populations increased progressively in both groups. Cellulolytic and methanogenic bacteria were present in both groups at 3 d of age. No protozoa were detected in calves of either group. In general, the most significant changes in bacterial populations and metabolic activity in both groups occurred between 4 and 6 wk of age. Although calves in both groups had similar patterns of bacterial development, calves in the early-weaning program tended to have high ruminal microbial activity at an earlier age than the conventionally weaned calves.

Animals↗
PubMedDate not supplied

Improving glycemic control: can techniques used in a managed care setting be successfully adapted to a rural fee-for-service practice?

The objective of this work was to improve glycemic control using case management supported by electronic diabetes care monitoring. Information for patients with diagnosed diabetes in a rural community was maintained in the Diabetes Care Monitoring System. In September 1998, counseling and medication management for glycemic control was intensified during individual office visits. And, from September 1998 to February 1999, 2-hour cluster visits modeled after a successful urban program were offered for groups of patients with elevated HbA1c values. The median (and 75th percentile) HbA1c values for the patient population decreased from 8.7% (10.9%) in March 1998 (N = 173) to 7.5% (9.3%) in March 1999 (N = 182) and was maintained at 7.5% (9.1%) through March 2000 (N = 182). Case management, including cluster visits, can be accomplished in a rural physician's office with the support of an electronic diabetes care monitoring system. This intensified approach decreased and sustained the HbA1c level by more than a percentage point for the patient population.

Adolescent↗
PubMed1987

Comparative larvivorous performances of mosquitofish, Gambusia affinis, and juvenile Sacramento blackfish, Orthodon microlepidotus, in experimental paddies.

Mosquitofish, Sacramento blackfish, or combinations of both species were stocked in experimental paddies. Cultured Culex tarsalis larvae, stocked weekly into each paddy, and wild Anopheles freeborni larvae were counted by dipping. At the end of the 12 week experiment, paddies were drained and the remaining fish and visible invertebrates counted. Data show the highest number of mosquito larvae in the blackfish-stocked paddies. This low larvivorous ability of blackfish may result from their rapid growth to ca. 70 mm standard length and a consequent shift to a filtering mode of feeding. Although blackfish populations decreased from one-third to one-half of their stocked levels and mosquitofish populations increased to very high levels, mosquito control seemed to be a function of species rather than just the number of predatory fish. The lower number of larvae in the control paddies compared with the blackfish paddies might be attributable to predatory invertebrate communities.

Agriculture↗
PubMed1991

[Population effects of fluctuation in fecundity and mortality in Triatoma infestans: simulation using Leslie matrices].

The population effects of known fluctuations in fecundity and mortality of T. infestans was studied through simulation using Leslie matrices. The effect of mortality and fecundity cycles was a stepped cycling through the growing phase, with no significant population decreases. Density dependent regulation stabilizes changes during the steady phase. The main effect is on population composition with the establishment of a regular annual cycle in the proportion of different age groups. Cycles with high number of larvae may be misinterpreted as an adult plague.

Animals↗
PubMed1984

Quantitative changes in T helper or T suppressor/cytotoxic lymphocyte subsets that distinguish acquired immune deficiency syndrome from other immune subset disorders.

Quantitative measurements of the immune cell subgroups, T helper (Leu 3+/OKT4+) cells and T suppressor/cytotoxic (Leu 2+/OKT8+) cells, were made in patients having acquired immune deficiency syndrome (AIDS) with Kaposi's sarcoma and in patients with AIDS and opportunistic infection, as well as in three other relevant populations. These included patients with lymphadenopathy syndrome, e.g., homosexually active males with lymphadenopathy who sought medical care for additional symptoms, and healthy male homosexuals, as well as a control population. Decrease in the number of T helper cells is characteristic of AIDS with Kaposi's sarcoma or opportunistic infection. Augmentation of the T suppressor/cytotoxic cell population is rare in AIDS with Kaposi's sarcoma but is more frequent in AIDS with opportunistic infection. Augmentation of the T suppressor/cytotoxic cell population, however, may occur in a variety of circumstances, including cytomegalovirus and other viral infections, in healthy, homosexually active males, and in otherwise healthy hemophiliac subjects receiving factor VIII treatment. Reduced T helper:T suppressor/cytotoxic cell ratio can be caused by either decrease in the number of T helper cells or augmentation of the T suppressor/cytotoxic cell population. Lowered T helper:T suppressor/cytotoxic cell ratio does not, by itself, help to distinguish between AIDS and other causes of reduced ratios. Quantitative measurements are needed to define the T subset changes. AIDS is characterized by decrease in the number of T helper cells and reduced T helper:T suppressor/cytotoxic cell ratio. The T helper (Leu 3+) and T suppressor/cytotoxic (Leu 2+) cell subpopulations can change independently. Identification of decrease in the number of T helper cells as an alteration that occurs independently of numerical change in other lymphoid subpopulations, such as T suppressor/cytotoxic cells and B cells, and the close association of the decrease in the number of T helper cells with AIDS are consistent with a distinct pathogenesis (and cause) for AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1983

A demographic investigation of the four Albanian communities living in Molise, Italy.

In a study of the four Albanian villages of Molise, Italy (Campomarino, Montecilfone, Portocannone and Ururi), demographic data have been obtained through national censuses and direct interviews of 382 subjects. The data demonstrate an increase of the population from 1700 to the middle of the twentieth century. From that time the population decreases in three villages, which now present a considerable degree of ageing. On the contrary, in the fourth village (Campomarino) the population continues to increase during the second half of the twentieth century, and now appears as a relatively young population. Immigration has proved to be somewhat elevated and shows a diminishing trend from the great-grandparents to the propositi. The endogamy decreases passing from the generation of the great-grandparents to that of the parents, and is higher along the paternal ascendence than along the maternal one. The exogamy, on the contrary, increases passing from the generation of the greatgrandparents to that of the parents, demonstrating a rather considerable mixture with the surrounding population. The percentage of Albanian surnames, or those of probable Albanian origin, has also been estimated in the parents of the propositi, and resulted to be higher in Montecilfone and Ururi, in comparison with Campomarino and Portocannone.

Adolescent↗
PubMed2002

Foodborne viruses.

Foodborne and waterborne viral infections are increasingly recognized as causes of illness in humans. This increase is partly explained by changes in food processing and consumption patterns that lead to the worldwide availability of high-risk food. As a result, vast outbreaks may occur due to contamination of food by a single foodhandler or at a single source. Although there are numerous fecal-orally transmitted viruses, most reports of foodborne transmission describe infections with Norwalk-like caliciviruses (NLV) and hepatitis A virus (HAV), suggesting that these viruses are associated with the greatest risk of foodborne transmission. NLV and HAV can be transmitted from person to person, or indirectly via food, water, or fomites contaminated with virus-containing feces or vomit. People can be infected without showing symptoms. The high frequency of secondary cases of NLV illness and - to a lesser extent - of hepatitis A following a foodborne outbreak results in amplification of the problem. The burden of illness is highest in the elderly, and therefore is likely to increase due to the aging population. For HAV, the burden of illness may increase following hygienic control measures, due to a decreasing population of naturally immune individuals and a concurrent increase in the population at risk. Recent advances in the research of NLV and HAV have led to the development of molecular methods which can be used for molecular tracing of virus strains. These methods can be and have been used for the detection of common source outbreaks. While traditionally certain foods have been implicated in virus outbreaks, it is clear that almost any food item can be involved, provided it has been handled by an infected person. There are no established methods for detection of viruses in foods other than shellfish. Little information is available on disinfection and preventive measures specifically for these viruses. Studies addressing this issue are hampered by the lack of culture systems. As currently available routine monitoring systems exclusively focus on bacterial pathogens, efforts should be made to combine epidemiological and virological information for a combined laboratory-based rapid detection system for foodborne viruses. With better surveillance, including typing information, outbreaks of foodborne infections could be reported faster to prevent further spread.

Caliciviridae Infections↗
PubMedDate not supplied

A preliminary comparison between local public health units in the Canadian Province of Ontario and in the United States.

This comparison between public health departments in the United States and in the Canadian Province of Ontario addresses the funding and staffing and the size and program content of local health departments after Canada's national health reform provided universal access to personal health services. Ontario's local health departments are required to provide a uniform set of public health services. In the United States, there is substantial variation among jurisdictions in kinds and amounts of services delivered. Ontario health units have staff sizes and budget levels that increase in proportion to population served, like those in the United States. But in Ontario, per capita expenditures increase with decreasing population, while the reverse is true in the United States. This anomaly may be attributed to lack of critical staff or elimination of key programs in small U.S. departments. Medical care of indigents probably accounts for the increased per capita costs seen in very large U.S. health departments. An estimated price for uniform public health services meeting the Ontario requirements in all U.S. jurisdictions as they were organized in 1989 is $5.8 billion per annum (not adjusted for inflation). If smaller health departments were consolidated, a savings of more than $1 billion could be realized. Even with this reorganization, average expenditures in smaller U.S. health departments would need to be doubled, and staff sizes increased by about 50 percent to meet Ontario's uniform public health program standards.

Data Collection↗
PubMed1982

Effects of cell motility and chemotaxis on microbial population growth.

A mathematical model is developed to elucidate the effects of biophysical transport processes (nutrient diffusion, cell motility, and chemotaxis) along with biochemical reaction processes (cell growth and death, nutrient uptake) upon steady-state bacterial population growth in a finite one-dimensional region. The particular situation considered is that of growth limitation by a nutrient diffusing from an adjacent phase not accessible to the bacteria. It is demonstrated that the cell motility and chemotaxis properties can have great influence on steady-state population size. In fact, motility effects can be as significant as growth kinetic effects, in a manner analogous to diffusion- and reaction-limited regimes in chemically reacting systems. In particular, the following conclusions can be drawn from our analysis for bacterial populations growing at steady-state in a confined, unmixed region: (a) Random motility may lead to decreased population density; (b) chemotaxis can allow increased population density if the chemotactic response is large enough; (c) a species with superior motility properties can outgrow a species with superior growth kinetic properties; (d) motility effects become greater as the size of the confined growth region increases; and (e) motility effects are diminished by significant mass-transfer limitation of the nutrient from the adjacent source phase. The relationships of these results for populations to previous conclusions for individual cells is discussed, and implications for microbial competition are suggested.

Bacterial Physiological Phenomena↗
PubMed1999

Interactions of allogeneic human mononuclear cells in the two-way mixed leucocyte culture (MLC): influence of cell numbers, subpopulations and cyclosporin.

With organ allografts considerable numbers of donor-type mononuclear cells are transferred to the recipient, leading to bilateral immunological interactions between donor and recipient lymphocytes. To study such bilateral immune reactions in detail, human two-way MLC were performed. In this model proliferation kinetics, patterns of activation, and survival of the two populations were analysed, and the relevance of initial cell subset composition, relative cell numbers, and the effect of immunosuppression on this co-culture were evaluated. It could be demonstrated that with an initial 50:50 ratio of two populations of allogeneic cells one population dominated after 21 days of co-culture in 78 out of 80 combinations (97%) tested; the other population decreased markedly after an initially stable phase of 6-7 days. With unequal starting conditions the larger population dominated when resting cells were used, but small populations of preactivated cells or separated CD8+ cells could also dominate. Depletion of CD16+ natural killer (NK) cells and of CD2- cells (B cell and monocytes) had no effect on domination. Addition of cyclosporin delayed or blocked the domination process while addition of IL-2 accelerated it. Disappearance of one population was associated with detection of apoptotic cells. The findings indicate that co-cultures of allogeneic mononuclear cells are generally not stable for more than 1 week, but lead to active elimination of one population. CD8+ cells and particularly preactivated cells seem to play the most important role in that process, while NK cells are of less importance. Cyclosporin can prolong survival of allogeneic cells in co-culture. These observations suggest that under the conditions of clinical organ transplantation even small amounts of immunocompetent donor cells transferred by the graft may persist for some time and may, thereby, have the chance to exert immunomodulatory functions.

Antigens, CD↗
PubMed2004

Fitness effects of a selfish gene (the Mus t complex) are revealed in an ecological context.

In wild house mice, genes linked to the t transmission distortion complex cause meiotic drive by sabotaging wild-type gametes. The t complex is consequently inherited at frequencies higher than 90%. Yet, for unclear reasons, in wild mouse populations this selfish DNA is found at frequencies much lower than expected. Here, we examine selection on the t complex in 10 seminatural populations of wild mice based on data from 234 founders and nearly 2000 progeny. Eight of the 10 populations decreased in t frequency over one generation, and the overall frequency of t haplotypes across all 10 populations was 48.5% below expectations based on transmission distortion and 34.3% below Mendelian (or Hardy-Weinberg) expectations. Behavioral and reproductive data were collected for 10 months for each population, and microsatellite genotyping was performed on seven of the populations to determine parentage. These combined data show t-associated fitness declines in both males and females. This is the first study to show evidence for a reduction in the ability of +/t males to maintain territories. Because females tend to mate with dominant males, impairment of territorial success can explain much of the selection against t observed in our populations. In nature, selection against heterozygote carriers of the t complex helps solve the puzzlingly low t frequencies found in wild populations. This ecological approach for determining fitness consequences of genetic variants has broad application for the discovery of gene function in general.

Analysis of Variance↗
PubMed1993

[Studies on the changes in infection rates of whipworm and ascaris in population after continuous chemotherapy].

The inhabitants with positive eggs of whipworm and ascaris in a village of Jiangdou County were examined and treated with different antihelmintic drugs twice a year. The uncured population were treated by drug administration once again. On an average the efficiency of drug treatment (cure rate x treatment rate) was 56.7% in whipworm and 64.5% in ascaris. The program had been carried out for five years. The positive rate of eggs of whipworm and ascaris in the population decreased from 64.7% and 52.1% to 2.7% and 4.1%, respectively, the mean increase in infection rates among population at 5 or 7 months after treatment was 2.68 (0.86-5.74)% and 6.94(1.72-17.27)%, respectively.

Albendazole↗
PubMed1994

Role of anaerobic ciliates in planktonic food webs: abundance, feeding, and impact on bacteria in the field.

We studied the dynamics of two populations of anaerobic ciliates, Plagiopyla sp. and Metopus sp., and of their potential prey, heterotrophic and phototrophic purple bacteria, in Lake Cisó throughout a 1-year cycle. The abundance of both ciliates was very low (less than 2 individuals per ml). During mixing, Plagiopyla ciliates exhibited high clearance rates (about 100 nl ciliate h), its integrated abundance increased with a net doubling time of 47 days, and its potential doubling times, as calculated from the number of bacteria consumed, ranged between 5 and 8 days. During stratification, the activity of Plagiopyla ciliates was reduced and the population decreased; this was related to the higher amounts of sulfide present. The impact of predation by the Plagiopyla population on bacterioplankton was found to be insignificant, less than 0.1% of bacterial biomass consumed per day. Thus, anaerobic ciliates cannot control the bacterioplankton in Lake Cisó because of both the low abundance over the period studied and the low feeding rates during certain periods. A review of available field studies suggests that this conclusion can be extrapolated to most other anoxic systems.

Journal Article↗