[Accurate localization and successful treatment of 23 cases of migrating pharynx and cervical esophageal foreign bodies]

Objective: To explore clinical features, diagnosis, localization, and therapeutic strategy of migratory pharyngeal and cervical esophageal foreign bodies. Methods: A total 23 cases of pharyngeal and cervical esophageal migratory foreign bodies were admitted between January 2015 and December 2021. There were 14 females and 9 males with the age ranged from 35 to 82 (55.0±12.7)years. In all the cases, esophageal CT was taken to confirm the esophageal foreign body. Multiplanar reconstruction (MPR) was performed to locate the foreign body from the horizontal, coronal and sagittal dimensions as well as the corrected reconstructed MPR. According to the location of the foreign body, appropriate surgical method was selected.The symptoms, complications, types of foreign body, positioning, surgical methods, and relevant information were recorded.Data were analyzed using the descriptive method and SPSS 25.0 software. Results: The clinical symptoms of 23 migrating esophageal foreign bodies included pharyngodynia (20/23), foreign body sensation (6/23), hoarsenss (1/23), difficulty in turning neck(1/23), difficulty in opening mouth (1/23), fever (7/23), poor appetite (1/23), and abdominal pain (1/23). The foreign bodies included 19 fish bones, 2 wires, 1 embroidery needle and 1 chicken bone. There were 9 cases (39.1%) of foreign bodies located in extraluminal cervical esophagus, 2 cases (8.7%) of foreign bodies located in the muscular layer of the cervical esophagus and 12 cases (52.2%) of foreign bodies located in pharynx. Twenty-one cases of foreign bodies were removed by cervical lateral incision, in which 11 were removed by cervical lateral incision directly, 10 by the second lateral cervical incision after the foreign bodies were accurately located by MPR and/or corrected MPR, 1 foreign body was removed by incision of the pharyngeal mucosa under suspension laryngoscope, 1 foreign body was removed by tracheoscopy. Compared with patients with intraluminal foreign bodies (n=308) treated in the same period, intake of fishbone [19 (19/23) vs. 133 (82.6% (43.2%, 133/308), OR=7.31] and first visit was more than 24 hours [20(87.0%, 20/23) vs. 77(25.0%, 77/308),OR=17.2] were the significant risk factors of migratory esophageal foreign bodies. Conclusions: MPR and the corrected MPR can accurately locate the migrating pharyngeal and cervical esophageal foreign bodies, by providing more intuitive imaging evidence for doctors, which provide imaging basis for formulation of surgical programs. Foreign bodies in pharyngeal and cervical esophagus need to be treated as soon as possible, otherwise they are easy to migrate, leading lead to serious complications.

Does religiosity in early adulthood predict change in filial eldercare norms after midlife among baby boomers?

This study investigated whether patterns of religious change from early to middle adulthood is associated with patterns of change in filial norms from midlife to later life. Tracking change across 45 years of the adult life span, we link developmental processes occurring at two stages of life using midlife as the point of inflection. Respondents consisted of 436 individuals in the Baby Boom generation who participated in the Longitudinal Study of Generations from Waves 1 (1971) to 9 (2016). We conducted latent class and latent transition analysis to identify religious classes and their transitions over several decades, and latent growth curve modeling to identify change in filial norms. We identified three religiosity classes in Waves 1 and 5-strongly religious, weakly religious, and moderately religious-and five patterns of religious transitions. These transitions were then used to predict change in filial norms between Waves 5 and 9. Respondents who remained weakly religious from early to mid-adulthood reported weaker filial norms in midlife, compared to those who became more religious, and declined more rapidly in their strength of filial norms after middle age. Those who stayed weakly religious also declined more rapidly post-middle age. Our findings link dynamics in religiosity and filial norms across disparate stages of the adult life span and suggest that religious orientations earlier in adulthood are linked to filial norms at time of life when responsibilities for eldercare become a concern for one's parents as well as oneself. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Socioeconomic Determinants of Anticipated and Actual Caregiving for Older Adults in India

This study investigates adult children's informal caregiving for, and living arrangements with, older parents in urban India. We differentiated between anticipated caregiving, for respondents whose parents and parents-in-law do not currently need care, and actual caregiving, for respondents who have at least one parent or parent-in-law with care needs. The results based on the 2011 Osaka University Preference Parameters Study reveal different antecedents of anticipated and actual care. Females have lower odds of anticipated care but there were no gender differences in actual caregiving. Married people have higher odds of anticipating financial assistance, but lower odds of providing actual caregiving. Religiosity is positively related to anticipated care and co-residing but not actual caregiving. Wealth increases the odds of anticipating providing housework as well as anticipated and actual financial assistance, while decreasing the odds of actual care. Given these findings, strengthening public pension and long-term care services is warranted.

Global prevalence, cascade of care, and prophylaxis coverage of hepatitis B in 2022: a modelling study

BACKGROUND

The 2016 World Health Assembly endorsed the elimination of hepatitis B virus (HBV) infection as a public health threat by 2030; existing therapies and prophylaxis measures make such elimination feasible, even in the absence of a virological cure. We aimed to estimate the national, regional, and global prevalence of HBV in the general population and among children aged 5 years and younger, as well as the rates of diagnosis, treatment, prophylaxis, and the future burden globally.

METHODS

In this modelling study, we used a Delphi process with data from literature reviews and interviews with country experts to quantify the prevalence, diagnosis, treatment, and prevention measures for HBV infection. The PRoGReSs Model, a dynamic Markov model, was used to estimate the country, regional, and global prevalence of HBV infection in 2022, and the effects of treatment and prevention on disease burden. The future incidence of morbidity and mortality in the absence of additional interventions was also estimated at the global level.

FINDINGS

We developed models for 170 countries which resulted in an estimated global prevalence of HBV infection in 2022 of 3·2% (95% uncertainty interval 2·7-4·0), corresponding to 257·5 million (216·6-316·4) individuals positive for HBsAg. Of these individuals, 36·0 million were diagnosed, and only 6·8 million of the estimated 83·3 million eligible for treatment were on treatment. The prevalence among children aged 5 years or younger was estimated to be 0·7% (0·6-1·0), corresponding to 5·6 million (4·5-7·8) children with HBV infection. Based on the most recent data, 85% of infants received three-dose HBV vaccination before 1 year of age, 46% had received a timely birth dose of vaccine, and 14% received hepatitis B immunoglobulin along with the full vaccination regimen. 3% of mothers with a high HBV viral load received antiviral treatment to reduce mother-to-child transmission.

INTERPRETATION

As 2030 approaches, the elimination targets remain out of reach for many countries under the current frameworks. Although prevention measures have had the most success, there is a need to increase these efforts and to increase diagnosis and treatment to work towards the elimination goals.

FUNDING

John C Martin Foundation, Gilead Sciences, and EndHep2030.

Stability and change of religiosity among baby boomers in adulthood: Associations with familism over time

While it is commonly understood that familism is influenced by religiosity, less is known about how religiosity between young adulthood and midlife is related to the trajectory of familism from midlife over the later life course. In this study, we identified a multidimensional typology of religiosity among baby boomers in young adulthood and midlife, explored how membership in this religious typology changed from young adulthood to midlife, and examined how transition patterns of religiosity were associated with familism over time. We used data from a sample of 471 baby boomers (mean age 19 years in 1971) from the Longitudinal Study of Generations (LSOG), Wave-1 (1971) through Wave-8 (2005). Using latent class and latent transition analysis, we identified three latent religiosity classes in Wave-1 (1971) and Wave-3 (1988): strongly religious, weakly religious, and privately religious, and identified nine transition patterns of religiosity from you between these waves from young adulthood to midlife. Using latent growth curve analysis (Wave-3 to Wave-8), we found that respondents who remained strongly or privately religious or whose religiosity increased had higher initial levels of familism (Wave-3) compared to those who stayed in the weakly religious class. However, the gap in familism across religiosity transition patterns decreased over time up to late middle age. Our findings indicate that while religiosity was positively associated with familism, its impact weakened over time possibly due to change in the centrality of family life and societal factors.

PASSING ON THE SILVER SPOON: THE ROLE OF EARLY LIFE CIRCUMSTANCES ON DOWNWARD INTERGENERATIONAL FINANCIAL TRANSFERS

Childhood circumstances are known to etch an indelible influence on individual outcomes across the life course such as education, income, and health. Yet relatively little is known about how early life exposures influence family outcomes. This study aims to determine how childhood exposures are associated with inter vivos downward intergenerational financial transfers among older adults aged 51-85 with at least one surviving adult child. Using cumulative (dis)advantage theory, I hypothesized that experiences in childhood shape intergenerational transfers patterns – with early-life advantage being able to provide more transfers than their disadvantaged counterparts. I used data from the US Health and Retirement Study waves 1998 to 2018 (n=32,095 individuals, 169,316 person-years) and estimated random effects models. The index of childhood socioeconomic status was constructed by adding the following dichotomized indicators: poor to fair family socioeconomic status, mother / father having less than HS education, father working for service sector, and moved due to financial difficulty. Downward transfers were defined as whether the respondent gave money, helped pay bills, or covered certain costs to children or grandchildren worth ≥US$ 500. The unadjusted model revealed that the probability of providing downward transfers among those with 1 and 2+ childhood socioeconomic status disadvantage was 5.4% and 3.8% less than those without disadvantage. The inverse association of early life disadvantage and downward transfers were preserved when basic demographic controls and household income and wealth were controlled for, although the magnitude slightly declined (4.0% and 3.1% lower probability for those with 1 and 2+ misfortunes, respectively).

Reciprocal associations between affectual, associational, and normative solidarity with parents during children's early to established adulthood

Intergenerational solidarity has become increasingly important to understand, as close family members mobilize the provision of social support across generations and contribute to family wellbeing. However, less is known about continuity and change in normative (eldercare norms), affectual, and associational solidarity with mothers and fathers as children emerge into full or established adulthood. Therefore, we focused on reciprocal associations between three dimensions of intergenerational solidarity (normative, affectual, and associational) as reported by young-adult children from their early twenties to late thirties. Data were derived from respondents in the Longitudinal Study of Generations: daughters reported about relationships with 291 mother-father pairs and sons reported about relationships with 309 mother-father pairs in 2000, 2005, and 2016. Autoregressive cross-lagged models prospectively predicted mutual influences among the three dimensions of solidarity across daughter-parent and son-parent relationships. In addition, multiple group analysis was conducted to examine the children's gender difference. We found that normative solidarity and emotional closeness with mothers were mutually reinforcing in daughters' and sons' parental relationships. However, normative solidarity predicted emotional closeness with fathers in both daughter-parent and son-parent relationships. The study concludes that sons and daughters establish eldercare norms based on emotional components of solidarity with mothers, and suggest that filial duty is a key reason why mother-child relations become close over the family life course.

Educational disparities in adult health across U.S. states: Larger disparities reflect economic factors

Introduction

Education level is positively associated with adult health in the United States. However, new research shows that the association is stronger in some U.S. states than others, and that states with stronger associations also tend to have poorer overall levels of health. Understanding why educational disparities in health are larger in some states than others can advance knowledge of the major drivers of these disparities, between individuals and states. To that end, this study examined how key mechanisms (economic conditions, health behaviors, family, healthcare) help explain the education-health association in each state and whether they do so systematically.

Methods

Using data on over 1.7 million adults ages 25-64 in the 2011-2018 Behavioral Risk Factor Surveillance System, we estimated the association between education level and self-rated health in each state, net of age, sex, race/ethnicity, and calendar year. We then estimated the contribution of economic, behavioral, family, and healthcare mechanisms to the association in each state.

Results

The strength of the education-health association differed markedly across states and was strongest in the Midwest and South. Collectively, the mechanisms accounted for most of the association in all states, from 55% of it in North Dakota to 73% in Oklahoma. Economic (employment, income) and behavioral (smoking, obesity) mechanisms were key, but their contribution to the association differed systematically across states. In states with stronger education-health associations, economic conditions were the dominant mechanism linking education to health, but in states with weaker associations, the contribution of economic mechanisms waned and that of behavioral mechanisms rose.

Discussion

Meaningful reductions in educational disparities in health, and overall improvements in health, may come from prioritizing access to employment and livable income among adults without a 4-year college degree, particularly in Southern and Midwestern states.

Religiosity of Baby-Boomers in Young Adulthood: Associations with Psychological Well-Being over the Life Course

Although several studies have discovered positive relationships between religion and various aspects of mental health, less is known about longitudinal associations between religiosity and psychological well-being over the life course. We examined how religious latent classes during the transition to adulthood are associated with trajectories of psychological well-being over 45 years. We selected 798 young-adults baby-boomers from the 1971 wave of the Longitudinal Study of Generation (mean age: 19 years) and tracked their psychological well-being over nine waves up to the 2016 wave (mean age: 64 years). Latent class analysis focused on four religiosity domains (religious service attendance, religious intensity, civic value of religion, literal beliefs) identified four distinct latent religious classes: strongly religious, weakly religious, liberally religious, and privately religious. Results of latent growth curve modeling showed that strongly religious baby-boomers during the transition to adulthood generally reported better psychological well-being than weakly religious baby-boomers at the same stage in life. In addition, psychological well-being in strongly, liberally, and privately religious baby-boomers followed a consistently upward trend across the life course, whereas among weakly religious baby-boomers psychological well-being followed an inverted u-curve (increased until mid-40s and decreased thereafter). Findings suggest that earlier religiosity may serve as a significant predictor affecting psychological well-being throughout the adult life course.

Religiosity Among Young-Adult Baby Boomers: Associations With Psychological Well-Being Over 45 Years

Past studies on the influence of religiosity on psychological well-being tended to be cross-sectional in nature and neglected generational differences. In this study, we assess how religiosity in early adulthood (mean age = 19) affects baby-boomers’ psychological well-being over the life course. We used waves 1 to 9 or 45 years of survey data from the Longitudinal Study of Generations (LSOG) (N=798), a sample of Southern Californians. First, we used latent class analyses on five domains to identify three typologies of baby boomers’ religiosity in early adulthood. We call these typologies “strongly religious,” “weakly religious,” and “personally religious.” Then, we used latent growth curve modelling to ascertain the influence of these religiosity typologies on psychological wellbeing from waves 1 to 9, controlling for time-invariant (religious affiliation, age, sex, race, parental income) and varying (religious salience, education, marital status, and annual income) factors. We found that the strongly religious have a consistently upward psychological wellbeing trend throughout the study period whereas wellbeing started to decline for the weakly religious and personally religious at around wave 6, on when they were about mid-40s to almost 50. We provide evidence that religiosity in early adulthood – a period in life characterized by the exploration of various options for the future brought about by greater personal freedom – positively influences baby boomer’s psychological wellbeing over the life course.

Reciprocal Associations Between Normative, Affectual, and Associational Solidarity With Parents in Young Adults

Intergenerational solidarity has become important as close family ties mobilize the provision of social support across generations and contribute to the family wellbeing. One popular approach to studying intergenerational cohesion in aging families is through the theoretical construct of intergenerational solidarity. However, less is known about the longitudinal and reciprocal associations between normative, affectual, and associational solidarity with mothers and fathers among young-adult children in the transition to adulthood. On the basis of the theoretical construct of intergenerational solidarity, we examined the reciprocal associations between three dimensions of intergenerational solidarity (normative, affectual, and associational) with parents in young-adult children from their early twenties to late thirties. Data were derived from 287 mother-son, 325 mother-daughter, 262 father-son, and 297 father-daughter groups who participated in the Longitudinal Study of Generations between 2000 and 2016. Autoregressive cross-lagged model with latent variables predicted the causal relations between three dimensions of solidarity across four parent-child groups. We found that young-adult sons’ perceived associational solidarity with parents predicted normative solidarity over time, whereas young-adult daughters’ perceived affectual solidarity with mothers predicted normative solidarity over time. In addition, young-adult daughters’ perceived normative solidarity predicted affectual solidarity for fathers over time. The present study found that young-adult sons and daughters have different ways establishing normative solidarity in their early twenties to late thirties according to parents’ gender. In addition, this study found that normative solidarity is beneficial for young-adult daughters developing emotional closeness with fathers over time.

The Mediating Role of Optimism on the Relationship of Activities of Daily Living and Well-Being Among Older Adults

Limitations on activities of daily living (ADL) and instrumental activities of daily living (IADL) can be deleterious to an older person’s life satisfaction and overall feelings of wellbeing. This study explored the possible mediating role of optimism on relationship between changes in ADL/IADL and life satisfaction over time. Using 2006-2016 data from the Health and Retirement Study (n=11,869), growth curve modelling was used to account for intra-individual and inter-individual changes in life satisfaction trajectories. All models controlled for age, sex, marital status, years of education, self-rated health, labor force status, log of household income, and attrition. In the baseline model without optimism and with all controls, coefficients for ADL (Beta=-0.13, P<0.01) and IADL (Beta=-0.12, P<0.01) were negatively significantly associated with life satisfaction. When optimism was introduced to the model, coefficients for both ADL and IADL increased by 0.01 and remained statistically significant, which suggests some mediating effects. When interaction terms between ADL/IADL and optimism were introduced, coefficients for ADL and IADL became statistically insignificant. However, the interaction between ADL and optimism (Beta=-0.02, P<0.05) was negatively significantly associated with life satisfaction. Findings suggest that optimism may protect against the negative impact of ADL/ IADL on life satisfaction. While changes in physical functioning and mobility may influence mental health status (e.g., depression, feelings of isolation), such consequences are not inevitable. Efforts are needed to highlight the positive aspects of aging and opportunities for life enrichment to increase morale and optimism among older adults.

Risk Aversion Among Male Older Adults: Does Veteran Status Matter?

Risk aversion determines how people make decisions and is known to predict a wide array of economic outcomes. This study assessed whether there are veteran status differences in risk aversion utilizing the Health and Retirement Study. Risk aversion is based on hypothetical financial gambles (N=2,121; 2006 wave) and self-reported risk attitudes on selected topics (N= 4,980; pooled 2014 and 2016 waves of the Leave-Behind Survey). Results from multivariate analyses reveal that veterans were more likely to be risk averse than nonveterans in financial matters, occupation, and health, but veteran status is not statistically significant in explaining risk taking in driving and leisure, and sport risk. Further research is needed to discern the role of military service-related experiences in determining levels of risk aversion among veterans and the extent to which risk aversion accounts for veteran status differences in later-life economic outcomes. Part of a symposium sponsored by the Aging Veterans: Effects of Military Service across the Life Course Interest Group.

Multidimensional Profiles of Religiosity: Do They Matter for Gen-Xers’ Psychological and Familial Well-Being?

Although researchers have suggested that religiosity is a multidimensional construct, less is known about the long-term effects of religiosity profiles on Generation X (born between 1965 and 1980) adults’ psychological and familial wellbeing over the life courses. Thus, the goal of this study is (1) to identify unobserved profiles of young-adult Gen-Xers’ religiosity based on religious attendance, religious intensity, spirituality, and religious ideology, (2) to investigate demographic factors that predict membership in these religiosity latent classes, and (3) to examine how these profiles of religiosity predict Gen-Xers’ psychological wellbeing (self-esteem, life satisfaction, and depression) and familial wellbeing (martial satisfaction, and affectual and associational solidarity toward their aging parents) in early and middle adulthood. We selected 462 Gen-Xers from the Longitudinal Study of Generation in the 2005 (mean age = 30.25) and the 2016 waves (mean age = 41.25). In terms of data analysis, the three-step latent class analysis was conducted. We identified four religiosity profiles among young-adult Gen-Xers: strongly religious, weakly religious, literalists but not religious, religious but not literalists. Less educated single Gen-Xers were more likely to be in the strongly religious class, and less likely to be in other classes. Gen-Xers in the strongly religious class reported high scores of psychological and familial wellbeing than those in other religiosity classes. Given that the religiosity of the U.S. population has declined substantially over the past few decades, our findings indicate that religiosity is an important resource for Gen-X adults’ psychological and familial wellbeing.

Formation of bacterial microcolonies on feed particles in the rumen

Examination of particulate feed that had been digested in vivo in the rumen, and of the leaves of specific legumes that had been digested in vitro by a mixed population of rumen bacteria, showed that very extensive glycocalyx-enclosed bacterial microcolonies developed on many of the available surfaces. Some of these adherent bacteria colonized a surface almost exclusively and attracted another specific type of bacteria as the second members of a distinct morphological consortium. The true extent of the exopolysaccharide glycocalyces of these adherent rumen bacteria was seen in cases where the fibers were attached at multiple points, and their role in microcolony formation and adhesion could be unequivocally ascribed.

Cytochemical Localization of Urease in a Rumen Staphylococcus sp. by Electron Microscopy

We describe a technique whereby intracellular urease activity can be localized by transmission electron microscopy. The ammonia produced from the enzymatic hydrolysis of urea is first precipitated with sodium tetraphenylboron and then replaced with silver to produce electron-dense silver tetraphenylboron. This direct reaction product deposition procedure was used to demonstrate the presence of membrane-bound urease of Staphylococcus sp. H3-22, a gram-positive ruminal bacterium.

Reduction of Selenate and Selenite to Elemental Selenium by a Pseudomonas stutzeri Isolate

A Pseudomonas stutzeri isolate rapidly reduced both selenite and selenate ions to elemental selenium at initial concentrations of both anions of up to 48.1 mM. Optimal selenium reduction occurred under aerobic conditions between pH 7.0 and 9.0 and at temperatures of 25 to 35 degrees C. Reduction of both selenite and selenate was unaffected by a number of anions except for sulfite, chromate, and tungstate ions, which inhibited both growth and reduction.

An improved method to illuminate and record a phytase assay in SDS-PAGE zymogram gels

Experimentation at the Lethbridge Research Center in Alberta, Canada using cross-polarized transmitted light to photographically record a staining technique on zymograms has proved to be successful with both color and black and white films. It has been possible to obtain the desired visible contrast without compromising the intensity of the enzyme activity bands. Increasing numbers of such PAGE gels are being submitted for photographic recording when it is believed that the image will be used for records, publication, scientific posters or AV presentations.

Directed evolution to produce an alkalophilic variant from a Neocallimastix patriciarum xylanase

The catalytic domain of a xylanase from the anaerobic fungus Neocallimastix patriciarum was made more alkalophilic through directed evolution using error-prone PCR. Transformants expressing the alkalophilic variant xylanases produced larger clear zones when overlaid with high pH, xylan-containing agar. Eight amino acid substitutions were identified in six selected mutant xylanases. Whereas the wild-type xylanase exhibited no activity at pH 8.5, the relative and specific activities of the six mutants were higher at pH 8.5 than at pH 6.0. Seven of the eight amino acid substitutions were assembled in one enzyme (xyn-CDBFV) by site-directed mutagenesis. Some or all of the seven mutations exerted positive and possibly synergistic effects on the alkalophilicity of the enzyme. The resulting composite mutant xylanase retained a greater proportion of its activity than did the wild type at pH above 7.0, maintaining 25% of its activity at pH 9.0, and its retention of activity at acid pH was no lower than that of the wild type. The composite xylanase (xyn-CDBFV) had a relatively high specific activity of 10128 micromol glucose x min(-1) x (mg protein)(-1) at pH 6.0. It was more thermostable at 60 degrees C and alkaline tolerant at pH 10.0 than the wild-type xylanase. These properties suggest that the composite mutant xylanase is a promising and suitable candidate for paper pulp bio-bleaching.

3(2H)-Benzofuranones and chromanes from liquid cultures of the mycoparasitic fungus Coniothyrium minitans

Two 3(2H)-benzofuranones and three chromanes were isolated from the mycoparasitic fungus Coniothyrium minitans. Their structures and absolute stereochemistry were determined by spectroscopic methods.

The effects of sequential inoculation of mixed rumen protozoa on the degradation of orchard grass cell walls by anaerobic fungus Anaeromyces mucronatus 543

The effects of protozoa on the degradation of plant cell walls (CW) during different growth stages of the fungus Anaeromyces mucronatus have been investigated. Since fungi show a marked lag in their in vitro cultures and many protozoa rapidly die during a prolonged incubation time, the effects of protozoa may vary according to the growth phase of the fungi. Therefore, the approach adopted was (i) to inoculate CW with fungus monoculture, (ii) to inoculate CW with fungus-protozoa coculture, or (iii) to sequentially inoculate fungal cultures that had been grown in CW for 24 (initial stage of growth), 48, and 72 h (late stage of growth) with mixed protozoa. When a fungus was associated with protozoa, a growth phase dependent effect was observed. Ruminal protozoa adversely affected the growth and activity when introduced in the initial growth stage of A. mucronatus, but a synergetic interaction was detected when added to late growth stage cultures. Although there is no immediate explanation for these results, the data suggested that protozoa can engulf the fungal zoospores, which are in ruminal fluids and (or) attached to small feed particles, but cannot engulf the fungal thallus that is tightly attached to feed particles by a rhizoidal system. Our data indicated that the protozoa did not influence cellulolysis by the fungi in exponential and (or) stationary phase, but they had a marked inhibitory effect on fungi that were in lag phase. Inhibition during lag phase could result from the protozoal predation of fungal zoospores that had failed to attach to substrates.

The impact of a clinic-based literacy intervention on language development in inner-city preschool children

OBJECTIVE

To determine the effect of a clinic-based literacy intervention on the language development of preschool children.

METHODS

A convenience sample of families presenting to 2 urban pediatric clinics for well-child care met the following criteria: the family was Latino or black and English- or Spanish-speaking; the child was 2 to 5.9 years old, with no neurodevelopmental disability, at a gestational age of 34 weeks or more, and not attending kindergarten. Participants at the first clinic (intervention group) were exposed to a literacy support program, based on Reach Out and Read (ROR), during the previous 3 years. At the second clinic (comparison group), a similar program started 3 months before the study. Parent-child reading activities were measured using the READ Subscale of the StimQ. Language development was measured using the One-Word Expressive and Receptive Picture Vocabulary Tests, and was performed in the child's primary language.

RESULTS

A total of 122 study participants (49 interventions and 73 comparisons) met inclusion criteria and completed all measures. Intervention and comparison families were similar for most sociodemographic variables. Intervention families reported reading together with their children approximately 1 more day per week. Intensity of exposure to ROR (measured by total number of contacts with the program) was associated with increased parent-child reading activities, as measured by the StimQ-Read Subscale (r = 0.20). Intervention children had higher receptive language (mean: 94.5 vs 84.8) and expressive language (mean: 84.3 vs 81.6). After adjusting for potential confounders in a multiple regression analysis, intervention status was associated with an 8.6-point increase (95% confidence interval [CI]: 3.3, 14.0) in receptive language (semipartial correlation [SR]coefficient = 0.27), and a 4.3-point increase (95% CI: 0.04, 8.6) in expressive language (SR = 0.17). In a similar multiple regression, each contact with ROR was associated with an adjusted mean 0.4-point increase (95% CI: 0.1, 0.6) in receptive score, and an adjusted mean 0.21-point increase (95% CI: 0. 02, 0.4) in expressive score.

CONCLUSIONS

ROR is an important intervention, promoting parental literacy support and enhancing language development in impoverished preschool children. Integration of literacy promoting interventions such as these into routine pediatric health care for underserved populations can be recommended.

Purification and characterization of a cellulase from the ruminal fungus Orpinomyces joyonii cloned in Escherichia coli

A cellulase from the ruminal fungus Orpinomyces joyonii cloned in Escherichia coli was purified 88-fold by chromatography on High Q and hydroxyapatite. N-terminal amino acid sequence analyses confirmed that the cellulase represented the product of the cellulase gene Cel B2. The purified enzyme possessed high activity toward barley beta-glucan, lichenan, carboxymethyl cellulose (CMC), xylan, but not toward laminarin and pachyman. In addition, the cloned enzyme was able to hydrolyze p-nitrophenyl (PNP)-cellobioside, PNP-cellotrioside, PNP-cellotetraoside, PNP-cellopentaoside, but not PNP-glucopyranoside. The specific activity of the cloned enzyme on barley beta-glucan was 297 units/mg protein. The purified enzyme appeared as a single band in SDS-polyacrylamide gel electrophoresis and the molecular mass of this enzyme (58000) was consistent with the value (56463) calculated from the DNA sequence. The optimal pH of the enzyme was 5.5, and the enzyme was stable between pH 5.0 and pH 7.5. The enzyme had a temperature optimum at 40 degrees C. The K(m) values estimated for barley beta-glucan and CMC were 0.32 and 0.50 mg/ml, respectively.

Localization of phytase in Selenomonas ruminantium and Mitsuokella multiacidus by transmission electron microscopy

The localization of phytase (myo-inositol-hexaphosphate phosphohydrolase) in the ruminal bacteria, Selenomonas ruminantium JY35 and Mitsuokella multiacidus 46/5(2), was determined with transmission electron microscopy. Phosphate produced from the enzymatic dephosphorylation of the calcium salt of phytic acid is precipitated as calcium phosphate. The calcium is then replaced with lead to produce electron-dense lead phosphate. This deposition of lead phosphate localized phytase in S. ruminantium JY35 and M. multiacidus 46/5(2) to the outer membrane, and confirmed intracellular expression of the enzyme in Escherichia coli pSrP.2, the recombinant clone which possesses the gene (phyA) encoding phytase (phyA) in S. ruminantium.

Effects of Tween 60 and Tween 80 on protease activity, thiol group reactivity, protein adsorption, and cellulose degradation by rumen microbial enzymes

Microbial enzymes extracted from mixed ruminal microorganisms were incubated for 2 h with casein and Tween 60 or Tween 80 at 10 concentrations ranging from 0 to 2.0% (vol/vol) to determine the effects of these nonionic surfactants on protease activation and thiol reactivity (unmasking of thiol groups). Rate and extent of protein adsorption to cellulosic substrate (barley straw) was measured in the presence of 0, 0.05, 0.10, 0.25, and 0.50% (vol/vol) Tween 80. Degradation of cellulose by a rumen bacterial fraction was measured over 48 h of incubation with and without Tween 60 or Tween 80 at 0.25% (vol/vol). Maximum accelerations of protease activity achievable with Tween 60 and Tween 80 (calculated from a Michaelis-Menten kinetics model) were 99.2 and 166.8%, respectively. Concentrations of Tween 60 and Tween 80 at which half the maximal velocities were attained were 0.28 and 0.20% (vol/vol), respectively. Tween 80 increased (P < 0.05) the rate and extent of adsorption of microbial protein to barley straw, and the effect was related to concentration of Tween 80 up to 0.10% (vol/vol). Initial rates of cellulose degradation with no surfactant, 0.25% Tween 60, or 0.25% Tween 80 were 0.60, 0.87, and 1.04 micrograms/ml per h, respectively. These nonionic surfactants were effective for enhancing rumen microbial protease and cellulase activities. Thus, further study is warranted to determine their potential for improving ruminant feeding.

Intraruminal supplementation with increasing levels of exogenous polysaccharide-degrading enzymes: effects on nutrient digestion in cattle fed a barley grain diet

The effects of supplying increasing ruminal doses of exogenous polysaccharide-degrading enzymes (EPDE) on rumen fermentation and nutrient digestion were studied using eight ruminally cannulated heifers, four of which were also duodenally cannulated, in a replicated Latin square. The heifers were fed a diet of 85.5% rolled barley grain and 14% barley silage (DM basis), and once daily they were given intraruminal doses of 0 (Control), 100, 200, or 400 g of a preparation containing polysaccharide-degrading enzymes. Enzyme treatment decreased ruminal pH (linear, P<.001) and increased ammonia N (quadratic, P<.001) concentration. The ruminally soluble fraction and effective degradability of feed DM in situ were increased (quadratic response, P<.001) by enzyme treatment. Ruminal administration of EPDE increased ruminal fluid carboxymethylcellulase and xylanase activities linearly (P<.001) and beta-glucanase activity quadratically (P<.01), decreased (quadratic response, P<.05) ruminal fluid viscosity, and did not affect (P>.05) ruminal fluid amylase activity. Elevated levels of fibrolytic activities in the rumen resulted in increased (quadratic, P<.001) carboxymethylcellulase, xylanase, and beta-glucanase (P<.01) activities in duodenal digesta. Duodenal amylase activity and reducing sugar concentration were also increased (quadratic responses, P<.001 and P<.05, respectively) by EPDE. Xylanase activity of fecal DM was increased linearly (P<.05) with increasing ruminal EPDE levels. Apparent digestibilities of DM, crude protein, and NDF were not affected by EPDE supplementation. Enzyme treatment did not affect (P>.05) urinary excretion of allantoin and uric acid, or concentrations of glucose and urea in blood.

A novel staining method for detecting phytase activity

Differential agar media for the detection of microbial phytase activity use the disappearance of precipitated calcium or sodium phytate as an indication of enzyme activity. When this technique was applied to the study of ruminal bacteria, it became apparent that the method was unable to differentiate between phytase activity and acid production. Strong positive reactions (zones of clearing around microbial colonies) observed for acid producing, anaerobic bacteria, such as Streptococcus bovis, were not corroborated by subsequent quantitative assays. Experimentation revealed that acidic solutions generated false positive results on the selected differential medium. Empirical studies undertaken to find a solution to this limitation determined the false positive results could be eliminated through a two step counterstaining treatment (cobalt chloride and ammonium molybdate/ammonium vanadate) which reprecipitates acid solubilized phytate. This report discusses the application of the developed two step counterstaining treatment for the screening of phytase producing ruminal bacteria as well as its use in phytase zymogram assays.

Characterization of a Neocallimastix patriciarum xylanase gene and its product

A xylanase gene (xynC) isolated from the anaerobic ruminal fungus Neocallimastix patriciarum was characterized. The gene consists of an N-terminal catalytic domain that exhibited homology to family 11 of glycosyl hydrolases, a C-terminal cellulose binding domain (CBD) and a putative dockerin domain in between. Each domain was linked by a short linker domain rich in proline and alanine. Deletion analysis demonstrated that the CBD was essential for optimal xylanase activity of the enzyme, while the putative dockerin domain may not be required for enzyme function.

Pneumonia in HIV-infected patients: a case-control survey of factors involved in risk and prevention

OBJECTIVE

To assess the factors that increase or decrease the risk of pneumonia with particular attention to immunization with pneumococcal and influenza vaccines in a group of HIV-infected persons.

DESIGN

A retrospective, case-control study based on information entered into a standard database and the medical record.

SETTING

Patients attending a referral clinic specializing in AIDS/HIV care at a public hospital.

PATIENTS

Among over 2000 subjects entered into a database in 8 years, 127 incidents of pneumonia were identified from the record. These cases were matched with 127 CD4 cell count matched, concurrent controls.

INTERVENTIONS

None.

MAIN OUTCOME MEASURE

The principal hypothesis was that chart review would find a decreased frequency of pneumococcal immunization in the pneumonia cases compared with matched controls.

RESULTS

Pneumococcal immunization was associated with a reduction of the risk of pneumonia by nearly 70%. The effect was seen even when immunization was given with a CD4 cell count of less than 100/mm3. Injection drug users and African-Americans had a twofold increased risk of pneumonia.

CONCLUSION

The study provides data to support the current recommendation for pneumococcal immunization of all HIV-infected persons. Although this conclusion could lead to renewed enthusiasm for increasing pneumococcal immunization rates in HIV-infected persons, it must be recognized that the study is observational and ascertainment bias cannot be excluded.

Isolation and characterization of angiogenin-1 and a novel protein designated lactogenin from bovine milk

This paper reports the isolation and characterization from bovine milk of two proteins: angiogenin-1, a recently discovered angiogenin, and lactogenin, a novel protein. Both proteins were adsorbed on and eluted closely from CM-Sepharose and Mono S. Lactogenin possessed a molecular weight (17 kDa) slightly higher than that of angiogenin-1 (15 kDa). Lactogenin had a higher ribonucleolytic (RNase) activity than angiogenin-1 towards yeast transfer RNA (tRNA). The Km values estimated for the RNase activities of angiogenin-1 and lactogenin were 51 microM and 40 microM respectively. Both were specific for poly C. The optimal pH for the RNase activities of angiogenin-1 and lactogenin was 7.75 and 7.5 respectively. Comparison of the amino acid sequences of cyanogen bromide fragments and the pyroglutaminase-treated N-terminal fragment of lactogenin with the sequence of bovine liver RNase (RNase BL4) revealed identity in residues 3-22, 24, 26-27, 37, 41-44, 46-50, 54, 56, 63, 72-80, and 83. Considerable similarity to the N-terminal sequence of angiogenin-2 was also noted. Both lactogenin and angiogenin-1 inhibited cell-free translation in a rabbit reticulocyte lysate system with an IC(50) below 100 nM.

Effect of Yucca schidigera on ruminal fermentation and nutrient digestion in heifers

In a replicated 3 x 3 Latin square experiment, six heifers (443 +/- 6.1 kg) fed a 61% barley grain:39% alfalfa silage diet (DM basis) were given intraruminal doses of powdered Yucca schidigera (YS). Doses of 0 (control), 20, or 60 g/d were given at 0800 daily. Ruminal content was sampled 0, 2, 4, and 6 h after dosing. Acidity, concentrations of reducing sugars, free amino acids, and peptides in the rumen were not affected (P > .05) by YS. Relative to control, ruminal ammonia concentration was reduced (P < .05) 2 h after YS dosing. Ruminal propionate concentration was increased (P < .05) by YS. Protozoal numbers in the rumen were lower (P < .05) with YS than without. Yucca did not affect (P > .05) rate or extent of in situ DM degradability. Fibrolytic, amylolytic, and proteolytic activities in ruminal contents were similar among treatments (P > .05). Dry matter intake, apparent digestibilities of DM, NDF, and CP, nitrogen balance, and microbial protein synthesis in the rumen were not affected (P > .05) by treatment. The effect of YS on ruminal ammonia concentration likely resulted from a decreased concentration of protozoa and, presumably, from ammonia binding by YS. The effect on ruminal propionate was probably a result of a selective inhibitory effect of YS on rumen microbial species.

Rearing stable fly larvae (Diptera: Muscidae) on an egg yolk medium

The growth and survival of Stomoxys calcitrans (L.) larvae on egg yolk medium inoculated with bacteria isolated from a colony of stable flies was evaluated. Five species of bacteria--Acinetobacter sp., Aeromonas sp., Empedobacter breve (Holmes & Owen), Flavobacterium odoratum Stutzer, and Serratia marcescens Bizio--were identified according to fatty acid profiles using a microbial identification system. Larvae failed to develop on uninoculated plates, confirming that bacteria are required to complete development. Larvae also failed to complete development on plates inoculated with Aeromonas sp. and S. marcescens, and died during the 1st instar. Larvae completed development on the remaining 3 bacterial species as well as on Escherichia coli (Migula). Survival was generally higher when larvae were reared on Acinetobacter sp. and F. odoratum compared with E. coli and E. breve. Egg density did not influence larval survival, although the variability in survival was lowest using 20 and 40 eggs per plate. Larval survival in mixed cultures of Acinetobacter and Flavobacterium averaged 22.7% lower than survival in the pure cultures, and averaged 21.6% higher in mixed cultures of Empedobacter and Flavobacterium compared with pure cultures. Larval survival in mixed cultures did not differ significantly from mean survival in pure cultures for combinations of Acinetobacter and E. coli, Acinetobacter and Empedobacter, E. coli and Empedobacter, and E. coli and Flavobacterium. Larval developmental time was faster on all mixed bacterial cultures compared with developmental time on pure bacterial cultures. Optimal sample sizes and egg numbers are presented for detecting specified differences in larval survival. This rearing procedure will be useful for studying insect-microbe interactions and evaluating mortality using bacterial agents.

Effect of micronizing full fat canola seed on amino acid disappearance in the gastrointestinal tract of dairy cows

Ruminal and total tract digestion of the amino acids (AA) in full fat canola seed was studied in two in situ experiments with three nonlactating, ruminally and duodenally fistulated dairy cows. Whole, full fat canola seed was hand-cracked or micronized (an infrared heat treatment) for 90 s and then studied in that form or after grinding to pass a 1.25-mm sieve. In the first experiment, the four sample types were ruminally incubated in nylon bags for up to 96 h. In the second experiment, they were sealed in mobile nylon bags, incubated ruminally for 16 h, placed in acidified pepsin for 1 h, and then inserted into duodenal cannulas for passage through the intestine. Amino acids in the canola seed and in the residues from in situ incubations were analyzed by HPLC. Micronization reduced ruminal disappearance of total AA and essential AA from full fat canola seed. Degradation kinetics from Experiment 1 indicated reduced soluble fraction and increased slowly degradable fraction of both total AA and essential AA following micronization. Micronization reduced disappearances of total AA and essential AA from whole canola seed in the total digestive tract but did not affect total tract digestion of total AA or essential AA in ground seed. Intestinal disappearance of total AA and essential AA from both whole and ground full fat canola seed were increased by micronization. Micronizing canola seed may be of value in improving AA utilization in ruminants.

Effect of dietary or abomasal supplementation of exogenous polysaccharide-degrading enzymes on rumen fermentation and nutrient digestibility

The effect of site of supplementation of a mixture of two crude preparations (Enzyme C and Enzyme X) of exogenous polysaccharide-degrading enzymes (EPDE) was studied in vivo using four ruminally and duodenally cannulated heifers (Exp. 1). The treatments were as follows: control (no EPDE), EPDE supplied through the diet (EF, 47.0 g/d), and EPDE infused continuously into the abomasum (EA, 41.6 g/d). Enzyme treatment increased the concentration of soluble reducing sugars (P < .05) and decreased NDF content (P < .05) in the treated feed, but this did not increase the rate or extent of in sacco disappearance of DM from the feed. Compared with control, ruminal fermentation was not affected by EF, but abomasal infusion increased (P < .05) rumen ammonia levels and shifted ruminal VFA patterns. Ruminal carboxymethylcellulase (CMCase) and xylanase activities were not affected by treatment. Abomasal infusion increased (P < .05) duodenal xylanase activity as compared with control and EF, but apparent digestion of DM, NDF, and CP were not affected by treatment. Negligible levels of CMCase and amylase reached the duodenum. During an in vitro experiment (Exp. 2), abomasal stability of the two EPDE was studied over a range of pH from 3.39 to .85, with or without pepsin. Carboxymethylcellulase activity (in Enzymes C and X) and beta-glucanase activity (in Enzyme C) were largely unstable against pepsin proteolysis (P < .001) and low pH (P < .001). Xylanase and amylase activities were resistant to pepsin but irreversibly inactivated at low pH. These two experiments showed that abomasal supplementation of EPDE did not successfully supply cellulases and amylases to the intestine, due partially to their limited resistance to low pH and pepsin proteolysis. Although EPDE significantly increased the level of xylanase activity at the duodenum, this did not significantly improve total tract digestion.

Effect of melengestrol acetate on development of 3-methylindole-induced pulmonary edema and emphysema in sheep

The involvement of melengestrol acetate (MGA) in susceptibility to developing pulmonary edema and emphysema following oral administration of 3-methylindole (3MI) was investigated using 10 Suffolk ewes receiving 0 or 0.15 mg of MGA daily (n = 5). Blood, urine and ruminal fluid were collected immediately prior to 3MI dosing (0.2 g/kg BW) and 1, 2, 3, 4, 5, 6, 12 and 24 h (blood); 3, 6, 9, 12 and 15 h (urine) and 1, 2, 3 and 12 h (ruminal fluid) afterward. Ewes receiving MGA experienced earlier (P < 0.05) onset of respiratory distress than the control ewes (2.5 vs 4 h), and upon euthanasia at 96 h, their lung weight relative to body weight tended (P < 0.10) to be lower. Ruminal 3MI concentrations did not differ between treatments (P > 0.05). Ewes receiving MGA had higher (P < 0.05) concentrations of 3MI metabolites in plasma prior to dosing than did control ewes, and these values tended to remain higher throughout the sampling period. Immunoreactivity assays indicated more pneumotoxin present in the lungs of MGA-treated ewes than controls. Lung damage was apparently more acute and accelerated in the MGA-treated ewes than in the controls. Urinary 3MI mercapturate concentrations differed (control > MGA-treated, P < 0.05) at 9, 12, and 15 h, but this difference was not apparent when urinary production (as estimated by creatinine concentration) was considered. The implications of these findings for MGA-treated feedlot heifers are currently under investigation.

Phytase activity of anaerobic ruminal bacteria

Phytase catalyses the release of phosphate from phytate (myo-inositol hexakisphosphate), the predominant form of phosphorus in cereal grains, oilseeds and legumes. The presence of phytase activity was investigated in 334 strains of 22 species of obligately anaerobic ruminal bacteria. Measurable activities were demonstrated in strains of Selenomonas ruminantium, Megasphaera elsdenii, Prevotella ruminicola, Mitsuokella multiacidus and Treponema spp. Strains isolated from fermentations with cereal grains proved to have high activity, and activity was particularly prevalent in S. ruminantium, with over 96% of the tested strains being positive. The measured phytase activity was found exclusively associated with the bacterial cells and was produced in the presence of approximately 14 mM phosphate. The most highly active strains were all S. ruminantium, with the exception of the one Mitsuokella multiacidus strain examined. Phytase activity varied greatly among positive strains but activities as high as 703 nmol phosphate released (ml culture)-1 were measured for a S. ruminantium strain and 387 nmol phosphate released (ml culture)-1 for the Mitsuokella multiacidus strain.

A method for the selective enumeration and isolation of ruminal Lactobacillus and Streptococcus

Ruminal lactic acid-producing bacteria were selectively isolated and enumerated using a one hour aerobic exposure prior to incubation on a semi-selective Lactobacillus medium, MRS, under anaerobic conditions. The technique allowed growth of pure cultures of ruminal Lactobacillus spp. and Streptococcus bovis without supporting the growth of pure cultures of any of the prominent ruminal bacterial species. In mixed cultures, the one hour aerobic pre-incubation inhibited the growth of the obligate anaerobic ruminal bacteria which can otherwise grow on the MRS medium, and the subsequent anaerobic incubation permitted maximal recovery of the weakly aerotolerant ruminal lactic acid-producing Lactobacillus spp. and Streptococcus spp. The efficacy of this technique in selecting exclusively for the lactic acid-producing bacteria was also demonstrated from populations of rumen bacteria from mixed culture end-point in vitro fermentation, continuous in vitro culture and isolations from fresh ruminal samples.

A review of bloat in feedlot cattle

Improvements in feedlot management practices and the use of various feed additives have reduced, but not eliminated, the occurrence of bloat in feedlot cattle. Feedlot bloat reduces the profitability of production by compromising animal performance and more directly by causing fatalities. In feedlots, bloat is associated with the ingestion of large amounts of rapidly fermented cereal grain and destabilization of the microbial populations of the rumen. An abundance of rapidly fermented carbohydrate allows acid-tolerant bacteria (e.g., Streptococcus bovis and Lactobacillus spp.) to proliferate and produce excessive quantities of fermentation acids. As a result, ruminal pH becomes exceedingly low, and this impairs rumen motility. Further, the excessive production of mucopolysaccharide or "slime" increases the viscosity of ruminal fluid and stabilizes the foam implicated in frothy feedlot bloat. Although protocols have been developed to treat feedlot bloat, the most profitable approach is to use management strategies to reduce its likelihood. Amount of roughage, grain processing techniques, selection of cereal grain (e.g., corn, barley, and wheat), dietary adaptation periods, and various additives (e.g., ionophores) can influence the occurrence of bloat in feedlot cattle. Successful management of these factors depends on a thorough understanding of the behavioral, dietary, and microbial events that precipitate bloat in feedlot cattle.

An endoglucanase from the anaerobic fungus Orpinomyces joyonii: characterization of the gene and its product

An endoglucanase gene (celA) was isolated from a genomic library of the ruminal fungus Orpinomyces joyonii. DNA sequence analysis of celA revealed an intronless gene encoding a typical signal sequence, an N-terminal catalytic domain, two repeated regions linked by a short Ser/Thr-rich linker and a domain of unknown function. The deduced amino acid sequence of the catalytic domain showed homology with the family 5 cellulases. While the catalytic domain of CelA was not homologous to the catalytic domain of the endoglucanase gene (EG3) from the ruminal bacterium Fibrobacter succinogenes, the repeated regions of CelA were very similar to the noncatalytic domain of EG3. This suggests that evolutionary shuffling of endoglucanase domains might occur among bacteria and fungi within the anaerobic ecosystem of the rumen. The celA gene was expressed in Escherichia coli, and the periplasmic endoglucanase was used for the characterization studies of the enzyme. CelA exhibited both endoglucanase and xylanase activities. Its pH optimum was 4 and the temperature optimum was 40 degrees C. Deletion analysis showed that the repeated sequences and C-terminal domain of CelA were not required for enzyme activity.

Efficacy of fenbendazole for treatment of giardiasis in calves

OBJECTIVE

To determine efficacy of fenbendazole for treatment of giardiasis in calves.

ANIMALS

Twenty male and 15 female Holstein calves (100 to 180 kg), naturally infected with Giardia sp.

PROCEDURE

In vitro fenbendazole susceptibility and resistance development was determined for a ruminant Giardia isolate by use of an adherence assay. Calves were treated as follows: group 1, a single administration of 5 mg of fenbendazole/kg of body weight; group 2, a single administration of 10 mg of fenbendazole/kg; group 3, 5 mg of fenbendazole/kg, every 24 hours for 3 days; group 4, 10 mg of fenbendazole/kg, every 24 hours for 3 days; group 5, 20 mg of fenbendazole/kg, every 24 hours for 3 days; group 6, 0.833 mg of fenbendazole/kg, every 24 hours for 6 days; and group 7, saline solution. Fecal Giardia cysts were counted on days -3 through -1 and 1 through 7, 9, 11, 13, 21, and 28 by use of sucrose gradient concentration and staining with a fluorescent monoclonal antibody.

RESULTS

The 50% adherence inhibition concentration was 0.024 +/- 0.002 microgram/ml, and resistance could not be detected after 5 weeks of continuous culture at sublethal concentration of fenbendazole (0.01 microgram/kg). Fenbendazole was 100% effective in eliminating cysts from the feces within 6 days for calves in treatment groups 2-6. Reinfection was observed in some calves within the 28-day study period.

CONCLUSIONS

Fenbendazole is effective in the elimination of Giardia infections in calves, but repeat treatments may be required in reinfected animals.

CLINICAL RELEVANCE

Fenbendazole is an effective and economical treatment for Giardia-associated diarrhea and growth rate reduction in calves.

Effect of salinomycin on giardiasis and coccidiosis in growing lambs

An experiment was undertaken to determine the effect of salinomycin on Giardia in vitro and on Giardia and coccidia in growing lambs. Concentrations of salinomycin above (3.9 micrograms/mL) reduced the adherence (index of viability) of Giardia S2 trophozoites by more than 50%. This strain did not develop resistance after repeated exposure to sublethal concentrations of salinomycin. Five of 40 lambs escaped natural infection by Giardia, and these were inoculated with > or = 500,000 cysts. Giardiasis (presence of cysts in feces) was confirmed in all lambs before commencement of the experiment. Coccidiosis (presence of oocysts) developed by natural exposure. Lambs were assigned randomly to diets containing 0, 4, 10, or 16 ppm of salinomycin. Giardia cyst and coccidia oocyst excretions were determined on 6 d during the first week and weekly thereafter. Giardia cysts were detected at each sampling date in all treatments (highest release, 2.3 x 10(6) cysts/g feces). The number of Giardia cysts shed in feces was not affected (P > .05) by salinomycin but did decline (P < .05) with time. Average infection rates remained above 50% until d 41 of the experiment and declined linearly (P < .05) with salinomycin concentration and time. The number of coccidia oocysts in feces was low (highest release, 6.8 x 10(4) oocysts/g feces), but shedding occurred in 38 of the 40 lambs. Treatment with salinomycin had a cubic effect (P < .05) on coccidia oocyst excretion, and no oocysts were detected beyond d 28. Treatment effect on average daily gain (P < .002), dry matter intake (P < .02), and final live weight (P < .07) was cubic, whereas carcass weight (P < .003) and dressing percentage (P < .08) were linearly affected by salinomycin concentration. Although a beneficial effect of 10 ppm salinomycin on lamb performance was apparent, the development of natural resistance makes it difficult to attribute this response to the control of coccidiosis or giardiasis.

The Rumen: A Unique Source of Enzymes for Enhancing Livestock Production

Increasing competition in the livestock industry has forced producers to cut costs by adopting new technologies aimed at increasing production efficiency. One particularly promising technology is feeding enzymes as supplements for animal diets. Supplementation of diets for non-ruminants (e.g., swine and poultry) with fibrolytic enzymes, such as cellulases, xylanases and beta-glucanases, increases the feed conversion efficiency and growth rate of the animals. Enzymatic hydrolysis of plant cell wall polymers (e.g., cellulose, xylan, beta-glucans) releases glucose and xylose and eliminates the antinutritional effects of beta-glucans and arabinoxylans. Enzyme supplementation of diets for ruminants has also been shown to improve growth performance, even though the rumen itself represents the most potent fibrolytic fermentation system known. Implementation of this technology in the livestock industry has been limited largely because of the cost of development and production of enzymes. Over the last decade, however, developments in recombinant DNA technology have increased the efficiency of existing microbial production systems and facilitated exploitation of alternative sources of industrial enzymes. The ruminal ecosystem is among the novel enzyme sources currently being explored. Understanding the role of enzymes in feed digestion through characterization of the enzymology and genetics involved in digestion of feedstuffs by ruminants will provide insight required to improve the products currently available to producers. Characterization of genes encoding a variety of hydrolytic enzymes, such as cellulases, xylanases, beta-glucanases, amylases, pectinases, proteases, phytases and tannases, will foster the development of more efficacious enzyme supplements and enzyme expression systems for enhancing nutrient utilization by domestic animals. Characteristics of the original source organism need no longer restrict the production of a useful enzyme. Recent reports of transgenic plants expressing fibrolytic or phytase activity and of transgenic mice able to produce endoglucanase in the pancreas speak to the feasibility of improving feed digestion through genetic modification of the feedstuffs and the animals.

Retrieval of clinical science information using an interactive activation and competition network

A method for storing and retrieving tabulated clinical science information is described. This method uses the interactive activation and competition network and belongs to the realm of parallel distributed processing. The advantages of this method are that information is readily retrievable by name and by any content, and that the best matched information is automatically returned when partially incorrect cues are given. Furthermore, it allows a variable degree of association among different units of information. The basic principles of this method are illustrated through a simple example from clinical bacteriology. In addition an application of this method to the retrieval of information in cardiology is presented.

Effects of giardiasis on production in a domestic ruminant (lamb) model

OBJECTIVE

To examine the effects of giardiasis on production and carcass quality, using growing lambs as a domestic ruminant model.

DESIGN

Randomized block.

ANIMALS

Giardia-free lambs: 23 in infected group, 24 in control group.

PROCEDURE

Six-week-old, specific-pathogen-free lambs were infected with Giardia trophozoites; control lambs received saline solution. Clinical signs of infection, body weight, and feed intake were determined for 10 weeks. Carcass weight and quality were determined at slaughter weight of 45 kg.

RESULTS

Giardia infection persisted from weeks 7 to 16. For 5 weeks after challenge exposure, abnormal feces were more frequently observed in infected lambs. Giardia infection was associated with a decrease in rate of weight gain and impairment in feed efficiency. Time to reach slaughter weight was extended in infected lambs, and the carcass weight of Giardia-infected lambs was lower than that of control lambs.

CONCLUSION

Giardiasis has a negative effect on domestic ruminant production.

CLINICAL RELEVANCE

Giardiasis in domestic ruminants is an economically important disease, thus necessitating control or elimination of the infection.

Emerging patterns of HIV transmission: the value of alternative surveillance methods

OBJECTIVE

To assess the current patterns of HIV transmission in Los Angeles County and determine if AIDS surveillance data accurately reflect these patterns.

DESIGN

Records-based cohort study.

METHODS

The demographic and HIV risk characteristics of persons considered to be recently infected with HIV (CD4+ count > 700 x 10(6)/l) were determined and compared with the characteristics of persons meeting the Centers for Disease Control and Prevention (CDC) 1993 AIDS case definition. Data were obtained for patients with HIV infection enrolled from four HIV outpatient clinics and analyzed between August 1991 and July 1993.

RESULTS

The patient cohort included 1857 persons with HIV infection; 1096 (59.1%) met the CDC 1993 AIDS case definition and 134 (7.2%) had a CD4+ lymphocyte count > 700 x 10(6)/l. The median CD4+ count for the group presumed to be recently infected was 809 x 10(6)/l. Persons considered recently infected with HIV were more likely than those meeting the AIDS case definition to be female (26.1 and 14.5%, respectively; P < 0.001), black (28.4 and 18.2%, respectively; P = 0.001), or male homosexual injecting drug users (IDU; 6.7 and 3.4%, respectively; P = 0.05). After controlling for confounding variables by logistic regression, persons recently infected were more likely to be female [adjusted odds ratio (OR), 3.4; 95% confidence interval (CI), 1.8-6.5; P < 0.001], black (adjusted OR, 1.6; 95% CI, 1.1-2.5; P = 0.02) or male homosexual IDU (adjusted OR, 2.4; 95% CI, 1.1-5.2; P = 0.02) than persons with AIDS.

CONCLUSIONS

Our results suggest that the HIV epidemic in Los Angeles County is currently advancing into different subpopulations and indicate that the current patterns of HIV transmission in the County are not fully reflected in standard AIDS surveillance activities. However, our data must be interpreted cautiously because of potential selection and misclassification biases. These findings illustrate the benefits of alternative surveillance mechanisms in detecting important changes in HIV transmission and defining groups at risk, especially in jurisdictions without HIV reporting.

A conjugative transfer system for the rumen bacterium, Butyrivibrio fibrisolvens, based on Tn916-mediated transfer of the Staphylococcus aureus plasmid pUB110

A limitation of genetic studies of the rumen bacterium, Butyrivibrio fibrisolvens, has been the availability of suitable vectors and transfer systems. Using the conjugative tetracycline resistant transposon, Tn916, the Staphylococcus aureus plasmid, pUB110, and the pUB110-based shuttle vector, pUBLRS, a conjugative transfer system was developed for B. fibrisolvens. B fibrisolvens donor strains H17c2 and H17c12, containing Tn916 and pUB110 or pUBLRS, respectively, were used in mating experiments with selected B. fibrisolvens strains. Kanamycin resistant transconjugants, containing pUB110, of strains 193, 194, and 195 were detected at a combined average frequency of 7.78 x 10(-7) per donor and 1.11 x 10(-5) per recipient. Transconjugants of strains 193 and 194, containing pUBLRS, were detected at an average frequency of 1.22 x 10(-6) per donor and 4.70 x 10(-8) per recipient. Southern hybridization analysis confirmed the presence of pUB110 and pUBLRS in transconjugants. Results indicated that Tn916 was necessary for mobilization of pUB110 as transconjugants were not detected when the transposon was absent from the donor strains. The ability to mobilize pUB110 and pUBLRS between B. fibrisolvens strains provides a conjugative transfer system that circumvents problems encountered with electroporation.

Microbial attachment and feed digestion in the rumen

Direct microscopic examination of the rumen and its contents shows microbial populations largely attached to feed particles in the digesta. Most feeds contain a surface layer that is resistant to attachment and therefore to digestion. Infiltration of these recalcitrant epidermal layers through damage sites or through focused enzymatic attack is essential for initiation of the digestive process. Proliferation of primary colonizing cells produces glycocalyx-enclosed microcolonies. Secondary colonizers from the ruminal fluid associate with microcolonies, resulting in the formation of multispecies microbial biofilms. These metabolically related organisms associate with their preferred substrates and produce the myriad of enzymes necessary for the digestion of chemically and structurally complex plant tissues. Upon accessing the internal, enzyme-susceptible tissues, microbial "digestive consortia" attach to a variety of nutrients, including protein, cellulose, and starch and digest insoluble feed materials from the inside out. Substances that prevent microbial attachment or promote detachment (e.g., condensed tannins, methylcellulose) can completely inhibit cellulose digestion. As the microbial consortium matures and adapts to a particular type of feed, it becomes inherently stable and its participant microorganisms are notoriously difficult to manipulate due to the impenetrable nature of biofilms. Properties of feed that place constraints on microbial attachment and biofilm formation can have a profound effect on both the rate and extent of feed digestion in the rumen. Developments in feed processing (i.e., chemical and physical), plant breeding, and genetic engineering (both of ruminal microorganisms and plants) that overcome these constraints through the promotion of microbial attachment and biofilm formation could substantially benefit ruminant production.

Production of 2-aminobutyrate by Megasphaera elsdenii

Production of the amino acid 2-aminobutyrate was studied in four strains of Megasphaera elsdenii grown on a lactate-based growth medium containing Bacto-casamino acids and yeast extract. Supplementation with threonine increased the production of 2-aminobutyrate in three of the four strains, but no substantial increase in production was noted with serine, methionine, or aspartate, all of which are potential sources for the precursor of 2-aminobutyrate, 2-oxobutyrate. L-Cycloserine, an inhibitor of alanine transaminases, decreased both alanine and 2-aminobutyrate production, suggesting that 2-aminobutyrate synthesis may share the same metabolic pathway as alanine synthesis or that 2-oxobutyrate can act as a substrate for alanine transaminases. Decreases in the production of 2-aminobutyrate were associated with a reduction in the catabolism of branched-chain amino acids in two of the four strains.