Morphological engineering of Streptomyces hygroscopicus var. geldanus: regulation of pellet morphology through manipulation of broth viscosity.

Actinomycetes, especially members of the genus Streptomyces, are responsible for producing the majority of known antibiotics. The production of antibiotics by filamentous organisms is often dependent on the morphology and size distribution of the pellet population within the culture. Particle interaction and subsequent pellet formation are primarily dependent on the rate of collision of particles in culture, which is in turn, a function of fluid turbulence. The microbial polysaccharide xanthan gum was used to artificially regulate the apparent viscosity (mu(a)) of S. hygroscopicus fermentation broths with the aim of controlling particle interaction, aggregation and hence pellet formation. An increase in both pellet count and biomass concentration from approximately 2,000 to 8,000 pellets ml(-1) and 0.9-2.1 g l(-1) dry weight of biomass, as well a decrease in the mean pellet volume from 0.014 to 0.004 mm(3) was observed in cultures supplemented with 3 g l(-1) xanthan gum. The addition of xanthan gum significantly alters fluid rheology by increasing the mu(a). Counter-intuitively, an increase in the mu(a) within the experimental range examined resulted in an increase in the rate of gas-liquid mass transfer. This was attributed to the predominantly diffusive nature of oxygen transfer in shake flask cultures.

Development of a robust microtiter plate-based assay method for assessment of bioactivity.

A microtiter plate-based assay was developed for the quantitative monitoring of bioactive compound production in Streptomyces hygroscopicus fermentation samples. The method reported demonstrates the successful application of the theories of disk diffusion based methods of bioactivity assessment, to a microtiter assay for high throughput analysis. The assay method facilitates the generation of the dose-response curve of test organisms (Escherichia coli, Bacillus subtilis and Saccharomyces cerevisiae) to a bioactive compound. Using this dose-response curve, the method facilitates definition of three distinct Minimum Inhibitory Concentration (MIC) values for use in the characterisation of the bioactive attributes of a sample. The assay uses established standard procedures to facilitate adaptation of the assay for use with a wider range of test microorganisms. Errors due to the assumption of a linear relationship between turbidity and biomass concentration are also reduced, due to incorporation of a step to convert turbidity to biomass concentration, for use in the calculation of bioactivity.

Morphological quantification of pellets in Streptomyces hygroscopicus var. geldanus fermentation broths using a flatbed scanner.

An image analysis technique has been developed to allow high throughput morphological characterisation of microbial fermentation broths containing spherical pellets greater than 100 microm in diameter. Images of stained Streptomyces hygroscopicus var. geldanus culture samples at three different inoculum levels were captured using a flatbed scanner, at a resolution of 21 microm per pixel (1200 dots per inch) and subsequently analysed leading to the generation of a morphological profile of each sample. The time taken for image capture and analysis of a prepared sample, containing approx. 2000 particles, was 3 min 6 s.

A workable solution for the pre-Medicare population.

Incremental reforms to expand health coverage among older Americans are justified by medical spending that increases with age and enrollment in employer insurance that decreases with age. Older Americans are also at risk of unexpected changes in health, access to health insurance, and earnings that could leave them poorly positioned financially for their retirement years. We propose offering universal access to Medicare at a community-rated premium, with premium vouchers for those with a history of low lifetime earnings and tax-preferred savings accounts to help everyone with the increased cost of insurance at older ages. These subsidies are available for coverage obtained from sources other than Medicare. We would set the eligibility age for the buy-in at 62. However, because enrollment in employer insurance does not drop precipitously at age 62, we regard the eligibility age as an adjustable design element that could resize the program to fit political and budgetary constraints.

Betwixt and between: targeting coverage reforms to those approaching Medicare.

Recent Medicare buy-in proposals agree on setting eligibility at age sixty-two but disagree on linking eligibility to loss of employer insurance or ability to pay. We examine arguments for targeting incremental coverage for older Americans in these ways. While access to retiree health insurance is declining, we question whether targeting loss of employer insurance can address many older Americans' insurance problems. Furthermore, focusing on persons ages sixty-two to sixty-four misses a large group of persons in poor health with limited resources. Efforts to improve coverage for older Americans should consider trade-offs between defining eligibility by age versus ability to pay.

The effect of culture conditions on the morphology of the dimorphic yeast Kluyveromyces marxianus var. marxianus NRRLy2415: a study incorporating image analysis.

The effect of changing environmental conditions on the morphology of the yeast Kluyveromyces marxianus var. marxianus NRRLy2415 was investigated in batch and continuous culture, using a previously developed computer-aided image analysis protocol [O'Shea and Walsh (1996) Biotechnol Bioeng 51: 679 690]. The morphology of the organism is primarily controlled by the specific growth rate, mu. This finding was contrary to a previous investigation [Walker and O'Neill (1990) J Chem Tech Biotechnol 49: 75-89]. When the organism is cultured in batch with excess oxygen, mu can approach the maximum specific growth rate, microm, and the primary morphology of the culture is yeast-like. However, if the organism is cultured in a chemostat, thereby controlling the growth rate, the morphology reverts to a pseudohyphal form. This response is thought to be an adaptation by the organism to its environment, whereby it assumes a foraging form under adverse environmental conditions. The use of computer-aided image analysis made possible the discrimination of subtle morphological differences between samples and the determination of the relationship between morphology and growth rate.

Use of mental health services by persons with a mental illness in nursing facilities: initial impacts of OBRA87.

OBJECTIVE: To identify mental health service use patterns in nursing facilities subsequent to nursing home reforms in the Omnibus Budget Reconciliation Act of 1987. METHODS: The study involves a retrospective analysis of Medicare Part B claims for mental health care for persons in a nursing facility in 1992 (N = 692) using the Medicare Current Beneficiary Survey. Mental health service use was described and analyzed using logistic regression. RESULTS: Only 26% of nursing facility residents and 36% of residents with a mental illness had a mental health visit in 1992. Logistic regression confirms analyses prior to 1987 showing older residents and those in rural areas remain less likely to receive mental health visits. DISCUSSION: Claims data collected after the passage of The Nursing Home Reform Act (NHRA) of 1987 indicate continued low levels of mental health treatment in nursing homes.

How many elders receive assistance? A cross-national comparison.

OBJECTIVES: To examine models of informal support received by elders in the United States and Sweden and to test whether differences in informal support appear to stem from demographic differences between the nations alone or whether cultural and historical differences must also be considered. METHODS: Samples with similar functional dependence, age 75 and older in the United States (n = 4,677) and Sweden (n = 1,378), were used to model cross-national differences in the association between country, age, sex, potential availability of kin support, and receipt of informal assistance. RESULTS: Patterns of informal help were higher in the United States than in Sweden but were qualified by higher order interactions among age, sex, and availability of kin support. DISCUSSION: Cultural differences predating current policies in both countries appear to influence informal support over and above what can be accounted for by demographic differences alone.

Effect of cell morphology on dead-end filtration of the dimorphic yeast Kluyveromyces marxianus var. marxianus NRRLy2415.

The dead-end filtration characteristics of the dimorphic yeast Kluyveromyces marxianus var. marxianus (formerly fragilis) NRRLy2415 were investigated for a range of mean cell morphologies, ranging from predominantly yeast-like to predominantly filamentous. Semiautomated image analysis was used to measure the mean cell specific surface area, Sv, and the mean ratio of cell length to equivalent cylindrical diameter, Ldm, in each broth. The method of Ju and Ho (Biotechnol. Bioeng. 1988, 32, 95-99) was used to show that for broths with Ldm values between 1.72 and 10.03, the voidage of cell pellets formed by centrifugation increased with increasing Ldm. In the pressure range 30-180 kPa, the specific filter cake resistance, alpha, was found to be related to pressure, DeltaP, through the equation alpha = alpha0(1 + kcDeltaP). The dependence of alpha0/Sv2 on Ldm was found to be qualitatively consistent with the pellet voidage data and the Carman-Kozeny equation. Considerably better agreement with the experimental data was obtained when the Kozeny constant, K, was treated as variable and related to Ldm through the equation K = 4.83 + 7.08 log10 Ldm. The cake compressibility constant, kc, was found to increase with increasing Ldm, a phenomenon consistent with the wide range of voidages that can be displayed by beds of long cylinders.

Profiles of hospital, physician, and home health service use by older persons in rural areas.

Using data from the Medicare Current Beneficiary Survey, we identify differences in hospital days, home health visits and physician office visits across five geographical categories. After controlling for individual characteristics and availability of health care providers, we find significant differences in service use. Results show greater use of home health care and less use of physician office visits and hospital care in rural areas. Because service use exhibits patterns of substitution and complementarity, future research on the use of health services needs to move beyond modeling the use of single services to modeling the range of services used.

Mental health services and the mortality of nursing home residents.

This article examines the impact of mental health services on the mortality rate for mentally ill nursing home residents. Previous research has documented the unmet need for mental health services among nursing home residents. Some research using small data sets has indicated patient benefits from treatment. This article examines the issue using data from the nationally representative National Nursing Home Survey. In a series of multivariate logistic regressions, treatment for mental illness provided by either general practice physicians or by mental health specialists appears to have few impacts on mortality. A statistically significant treatment effect is found only for residents with schizophrenia, other psychoses, or anxiety disorders when treated by mental health specialists. The results are discussed with reference to ongoing reforms for mental health care in nursing homes.

Morphological characterization of the dimorphic yeast Kluyveromyces marxianus var. marxianus NRRLy2415 by semi-automated image analysis.

A semiautomatic image analysis method has been developed to characterize the morphology of the dimorphic yeast Kluyveromyces marxianus var. marxianus (formerly fragilis) NRRLy2415 undergoing alcoholic fermentation of cheese whey permeate. The method is capable of separating cells into six defined categories, varying from simple ovoid yeast cells to branched mycelial cells. A sample size of 300 cells was found to be sufficient to obtain a statistically significant categorization. The processing time for a sample was found to be approximately 90 min. In addition to qualitative characterization, the method permits the measurement of geometric properties such as the width, length, and volume of individual cells or clusters of cells. When the cells analyzed by the automatic method were categorized on a manual basis, the error level in the automatic routine was found to be less than 3%.

The health-wealth connection: racial differences.

This article examines the theoretical connection between health capital and financial capital in an economic life-cycle model, exploring possible explanations for racial differences in capital accumulation behavior. Using data from the Health and Retirement Survey, detailed descriptive analysis and a comparison of regression models for health and financial capital are presented. The results, although preliminary and based on cross-section data, suggest possible racial differences in the connection between health and wealth and deserve further study.

Demand for insurance by elderly persons: private purchases and employer provision.

Studies of the demand for health insurance by elderly persons often inadequately address the distinctions between those who receive insurance through a former employer and those who purchase insurance on their own. The failure to distinguish these two modes of supplementing Medicare can lead to an inability to identify the effects of important independent variables. Using data from the Survey of Income and Program Participation this paper examines the demand for employer provided health insurance among retired pensioners using a bivariate probit model with partial observability and compares these results to other models of insurance demand among elderly persons. The results indicate that unobserved factors reducing the probability of being offered employer provided insurance are associated with increased acceptance. A comparison of the employer provided results with results from other models of the demand for privately purchased insurance indicates that different independent variables may determine the probability of having these types of insurance. Previous studies of insurance that have not distinguished between these two types of insurance may not provide reliable estimates of the relationship between independent variables and the probability of insurance coverage.

Employment trends and the traditional baccalaureate health administration student.

Baccalaureate programs in health administration serve both traditional undergraduates--usually age 18 to 22 with little experience--and older adult students with more experience. The former group of students, as well as some older students who are changing their fields, are sometimes not as well informed as graduate students and adult undergraduates with health care experience about the impact of changes in the health care sector on employment opportunities. Furthermore, career advisers in placement offices may not be able to keep pace with the rapid change in health care. This article examines past and future changes in employment opportunities for baccalaureate students, with a particular focus on the changes that are occurring in sector employment growth. The implications of the continued shrinking in the acute care sector, the growth of managed care, the increased complexity of physician group management, and the ongoing rise in long-term care for employment are too often missed by students with limited experience in health care.

Determinants of the use of specialist mental health services by nursing home residents.

OBJECTIVE: This study examines the effects of resident and facility characteristics on the probability of nursing home residents receiving treatment by mental health professionals. DATA SOURCES/STUDY SETTING: The study uses data from the Institutional Population Component of the 1987 National Medical Expenditure Survey, a secondary data source containing data on 3,350 nursing home residents living in 810 nursing homes as of January 1, 1987. STUDY DESIGN: Andersen's health services use model (1968) is used to estimate a multivariate logistic equation for the effects of independent variables on the probability that a resident has received services from mental health professionals. Important variables include resident race, sex, and age; presence of several behaviors and reported mental illnesses; and facility ownership, facility size, and facility certification. DATA COLLECTION/EXTRACTION METHODS: Data on 188 residents were excluded from the sample because information was missing on several important variables. For some additional variables residents who had missing information were coded as negative responses. This left 3,162 observations for analysis in the logistic regressions. PRINCIPAL FINDINGS: Older residents and residents with more ADL limitations are much less likely than other residents to have received treatment from a mental health professional. Residents with reported depression, schizophrenia, or psychoses, and residents who are agitated or hallucinating are more likely to have received treatment. Residents in government nursing homes, homes run by chains, and homes with low levels of certification are less likely to have received treatment. CONCLUSIONS: Few residents receive treatment from mental health professionals despite need. Older, physically disabled residents need special attention. Care in certain types of facilities requires further study. New regulations mandating treatment for mentally ill residents will demand increased attention from nursing home administrators and mental health professionals.

The provision and use of mental health services in nursing homes: results from the National Medical Expenditure Survey.

Data from the Institutional Population Component of the National Medical Expenditure Survey were used to provide national estimates of annual mental health service provision and use in nursing homes. In addition, the relationship between service provision and setting characteristics such as ownership, size, Medicaid certification, and chain status was examined. Although more than three quarters of residents with a mental disorder resided at a nursing home that provided counseling services, fewer than one fifth actually received any mental health services within the year.

Ability to pay for retiree health benefits.

This paper examines retired persons who received employer-provided health benefits in 1987. The sociodemographic, health, and economic characteristics of these elderly persons are compared to the total elderly population. Two methods of estimating retiree insurance purchase are considered and indicate 13% to 20% of retirees would be unable to afford benefits without an employer subsidy. The percentage of persons unable to purchase the employer-provided benefits drops significantly if some subsidy is maintained. The results indicate substantial differences in ability to purchase insurance by sociodemographic characteristics. The future of retiree health benefits in a reformed health care system is discussed.

Mental health services for nursing home residents: what will it cost?

The Nursing Home Reform Act of 1987 requires nursing homes to provide basic mental health services for all residents and to give active mental health treatment, a set of specialized mental health services, to those residents who are admitted with a serious mental illness. This article examines the potential size of the nursing home population who will require mental health services, its demographic composition, and the facilities in which these individuals reside using the Institutional Population Component of the National Medical Expenditure Survey. Estimates of the potential costs of providing monthly psychotherapy and pharmacological management to this population in nursing homes indicate that the mandate will have significant financial effects on nursing facilities. Conclusions about how the requirements for maintaining the mental and psychosocial well-being of nursing home residents may affect the future of nursing home care and mental health care are considered.