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Biomedical subjects

E L Schneider

Publications and source records attributed to E L Schneider.

At least 19 recordsLinked to original sources
PubMed2000

SEM studies on vessels in ferns. 17. Psilotaceae.

Perforation plates are reported in aerial and subaerial axes of Psilotum nudum and in aerial axes of Tmesipteris obliqua. In Psilotum, both perforations lacking pit membranes and perforations with pit membrane remnants were observed. Perforation plates in Psilotum may consist wholly of one type or the other. In Tmespteris, perforations have threadlike pit membranes or consist of porose pit membranes. Wide perforations alternating with narrow pits, a conformation observed in various ferns, were observed in Psilotum (subaerial axes). In Psilotum, perforations are more common in metaxylem than in protoxylem; perforations in protoxylem consist of primary wall areas containing small circular porosities or relatively large circular to oval perforations. There are no modifications in the secondary wall framework of protoxylem or metaxylem in Psilotum or Tmesipteris that would permit one to distinguish presence of perforations or perforation plates with light microscopy, and scanning electron microscopy (SEM) is required for demonstration of porose walls or perforations. The tracheary elements of the Psilotaceae studied have no features not also observed in other ferns with SEM.

Journal Article↗
PubMed1999

Sem studies on vessels in ferns. 12. Marattiaceae, with comments on vessel patterns in eusporangiate ferns.

Scanning electron microscopy (SEM) of tracheary elements of roots of five species from four genera of Marattiaceae and of the rhizome of one species revealed vessel elements present in all. The secondary wall framework of perforation plates is the same as that of lateral wall pitting for vessel elements in all species. Thus, no specialization is present in perforation plates of Marattiaceae compared to the simplified morphology of perforation plates of some leptosporangiate ferns (e.g., Dryopteridaceae, Polypodiaceae, and Pteridaceae). The difference between lateral wall pitting and perforation plates in tracheary elements of Marattiaceae cannot be seen by light microscopy (in which pit membranes are transparent), but is evident with SEM. Diversity in structure of perforation plates (especially the alternation of wide and narrow perforations within a plate) and presence of web-like pit membrane remnants are evident. Vessels are widespread in both leptosporangiate and eusporangiate ferns, although specialization in perforation plates (e.g., bars few and more widely spaced in lateral wall pitting of a given vessel element) is to be expected only in ferns of habitats with marked fluctuation in water availability. Vessels of Marattiaceae lack such specializations and are thus are correlated with the mesic habitats characteristic for the family.

Journal Article↗
PubMed1997

Manipulating the aggregation and oxidation of human SPARC in the cytoplasm of Escherichia coli.

Human SPARC (secreted protein acidic and rich in cysteine), an extracellular matrix protein containing 14 cysteine residues, was found to partition equally between soluble and insoluble cellular fractions when overexpressed in the Escherichia coli cytoplasm. While the growth temperature and medium pH had little effect on inclusion body formation, co-overproduction of the dnaKJ operon, but not of the groE operon, suppressed aggregation at the expense of intracellular accumulation. Although both forms of the protein were fully reduced in wild-type cells, 70% to 85% of soluble and insoluble SPARC could be converted into oxidized species in a thioredoxin reductase (trxB) null mutant following incubation on ice. Approximately 15% to 20% of SPARC exhibited the electrophoretic mobility of the biologically active protein. Overproduction of the dnaKJ operon in trxB cells decreased the formation of disulfide-bonded SPARC multimers in the aggregated material but not in its soluble counterpart. Our results suggest that the activity responsible for disulfide bond formation in trxB mutants acts at the post-translational level and is able to freely diffuse within inclusion bodies.

Amino Acid Sequence↗
PubMed1996

Cloning of rat GADD45 gene and induction analysis following ionizing radiation in vivo.

A gene encoded GADD45 was isolated from rat and revealed four exons along with a p53 binding consensus sequence and a putative AP-1 site in the third intron. This suggests that the rat GADD45 gene is also involved in the p53 signal pathway related to the G1 cell cycle checkpoint. The rat GADD45 mRNA was induced within 30 min in liver and increased as a function of gamma-irradiation. We found that mRNA expression differed substantially in a variety of tissues (brain, liver, kidney, and spleen). The finding of in vivo induction of GADD45 gene may provide insight into the role of GADD45 gene in DNA repair.

Alkylating Agents↗
PubMed1996

Imbalance in an older population: an epidemiological analysis.

Difficulties with balance are associated with limitations in activities of daily living. There is little information, however, about the epidemiology of imbalance. Imbalance, defined as the inability to maintain a full-tandem stand for 10 seconds, was assessed as part of an interview with 2,018 residents of Marin County, California, age 55 and older. The likelihood of imbalance was greater in women, those aged 85 and older, and those with less than 12 years of education. It was also associated with specific chronic conditions, including a history of hypertension, stroke, or cataracts. Even after adjusting for these conditions, imbalance was associated with reduced lower-body strength as well as poor short-term memory, hip pain, vision problems, abstention from alcohol, and current cigarette smoking. With those aged 85 and older representing the fastest growing age group in developed nations, imbalance may become a major health problem.

Activities of Daily Living↗
PubMed1994

Cloning of the rat Gadd45 cDNA and its mRNA expression in the brain.

We cloned the rat Gadd45 (growth arrest and DNA damage inducible) cDNA and examined its mRNA induction by gamma-ray irradiation in the rat brain. The rat Gadd45 cDNA sequence was highly homologous to the previously published human and hamster cDNAs, and was partially similar to the 28S rRNA gene. The mRNA encoding rat GADD45 was induced in the brain after gamma-ray irradiation. This finding indicates that Gadd45 is an inducible gene following the ionizing radiation, not only in cultured cells in vitro, but also in animal tissues in vivo.

Amino Acid Sequence↗
PubMed1994

Modifications of alkaline microgel electrophoresis for sensitive detection of DNA damage.

The alkaline microgel electrophoresis technique was modified to achieve a substantial increase in sensitivity for the detection of radiation-induced DNA damage in human lymphocytes. This increased sensitivity was achieved through: (1) the addition of free radical scavengers to the electrophoresis solution to reduce DNA damage generated during alkaline unwinding and electrophoresis; (2) the modification of the electrophoresis unit to achieve a more uniform electric field; (3) the use of YOYO-1, a DNA dye, producing fluorescence 500-fold more intense than ethidium bromide; and (4) the introduction of an image analysis system for the quantitation of DNA migration. In addition to increasing sensitivity, these modifications have increased the speed with which observations can be quantified, and improved reproducibility from experiment to experiment. In human lymphocytes, these modifications have resulted in an increased sensitivity of several fold, allowing the detection of DNA damage in the range of 50 mGy. This increased sensitivity for the detection of DNA damage should extend the utility of this technique.

Benzoxazoles↗
PubMed1992

The aging of the aged: challenges for gerontology & geriatrics in the United States.

It comes as no surprise that global graying will be one of the most pressing issues of the coming century. The most rapidly growing age group in all developed countries is the one with persons aged 85 and older. Often referred to as the "oldest old", the aging of the aged reflects a universal concern being experienced in the United States as well as in other industrialized countries, such as Japan. This paper addresses the challenges that such changes present for gerontology and geriatrics. Contextual projections of population trends and of life expectancy, as well as actual health care costs and estimated government health care expenditures will be compared for the United States and for Japan. Among the geriatric challenges being confronted are (1) the need to separate aging from disease, (2) the need for more geriatric centers and available geriatricians to serve the aged, (3) the introduction of health care strategies of prevention and case management, (4) responses to the notion of health care rationing, and (5) the ultimate importance of research ranging from the biological and molecular to the behavioral, social, and health service delivery. Global aging presents a gerontological imperative that may best be understood by examining policy recommendations and future policy decisions.

Aged↗
PubMed1992

The growth of gerontology & geriatrics in the United States.

Since the confirmation of the Older American's Act (OAA) in 1965, the growth of gerontology and geriatrics, has literally come of age in the United States. Although individual aging courses were offered in higher education prior to passage of the OAA, few gerontology programs had been established. On campuses where gerontology courses were available, they represented electives connected with a pre-existing discipline, such as social work or family studies. However, 1965 was a watershed year for gerontology instruction since it heralded the provision of federal funding support, beginning with that of the Administration on Aging (AoA), to help develop, pilot, and oversee gerontological programs in American institutions of higher learning. Initially, instruction was at an undergraduate level, but later gerontology degree programs were established at the master's level, with the first gerontology degree program originating at North Texas State University, in 1967. This program was followed a year later (1968) by a program at the University of South Florida. While funding from AoA began in 1966, funding from other federal agencies (e.g., the Bureau of Health Professions (BHP); the National Institute on Aging (NIA); the National Institute of Mental Health (NIMH), Mental Disorders of Aging Branch; and the Veteran's Administration (VA))--the five agencies that became the basis for a 1984 and 1987 Report on Education and Training in Geriatrics and Gerontology,--did not begin until the mid 1970s. The mid 1970s reflected the growing awareness of the demographic shift in America and around the world, particularly in developed nations.(ABSTRACT TRUNCATED AT 250 WORDS)

California↗
PubMed1991

A microgel electrophoresis technique for the direct quantitation of DNA damage and repair in individual fibroblasts cultured on microscope slides.

We demonstrate by single-cell microgel electrophoresis that the 2 main techniques, trypsinization and scraping, used to collect normal diploid mammalian cells cultured in monolayer induce DNA damage. To minimize this potential interference with studies on DNA damage and repair, we have standardized the single-cell gel electrophoretic (SCG) technique for the in situ quantitation of DNA single-strand breaks and alkali-labile sites in cultured human-fibroblasts. To demonstrate the utility of this technique, human neonatal foreskin-derived fibroblasts were allowed to attach to frosted microscope slides and then either irradiated with X-rays (25-200 rad) or treated for 1 h with hydrogen peroxide (2.2-140.8 mumoles). Treatment with either agent induced a dose-dependent increase in DNA migration. At equal levels of DNA damage, cell-to-cell variability in DNA migration was more heterogeneous for hydrogen peroxide-treated cells than for X-irradiated cells. A time course study to evaluate the kinetics of DNA repair for X-ray (200 rad)-induced damage indicated that the damage was completely repaired within 2 h. Applications of this technique for in vitro toxicology are discussed.

Cell Adhesion↗
PubMed1991

Basal DNA damage in individual human lymphocytes with age.

A role for DNA damage is central to many theories of aging, but attempts to show an increase in DNA damage with age have yielded contradictory results. However, previous experiments have been of limited sensitivity, only able to examine induced (not basal) damage or pooled (not individual) cells. In this report, we apply a novel technique (Singh et al., 1988) to directly measure basal levels of DNA single-strand breaks and alkali-labile sites in individual human peripheral blood lymphocytes (PBL) obtained from young (less than 60 years) and old (more than 60 years) male donors. This approach shows that while average changes with age are small, changes in certain individuals and in certain cells may be large: the mean increase in damage was only 12%, but the increase in a subpopulation of highly damaged lymphocytes was 5-fold. However, most of this increase was contributed by just 3 of 17 older subjects. Further characterization of these individuals may shed light on the relationship between DNA damage and aging.

Adult↗
PubMed1991

Prohibitin, an evolutionarily conserved intracellular protein that blocks DNA synthesis in normal fibroblasts and HeLa cells.

Genes that act inside the cell to negatively regulate proliferation are of great interest because of their implications for such processes as development and cancer, but these genes have been difficult to clone. This report details the cloning and analysis of cDNA for prohibitin, a novel mammalian antiproliferative protein. Microinjection of synthetic prohibitin mRNA blocks entry into S phase in both normal fibroblasts and HeLa cells. Microinjection of an antisense oligonucleotide stimulates entry into S phase. By sequence comparison, the prohibitin gene appears to be the mammalian analog of Cc, a Drosophila gene that is vital for normal development.

Amino Acid Sequence↗
PubMed1990

Aberrant gene expression and aging: examination of tissue-specific mRNAs in young and old rats.

It has been suggested that aberrant gene expression may play a role in aging. To test this possibility, we examined the steady-state mRNA levels for five tissue-specific genes of known function in young (6 month) and old (24 month) rats. Six different tissues from three animals of each age were analyzed using a hybridization assay estimated to be able to detect one mRNA copy per cell. At this level of sensitivity, no aberrant gene expression was seen. The results indicate that these tissue-specific genes retain their fidelity of expression with age.

Aging↗
PubMed1990

The aging of America. Impact on health care costs.

The rapid growth of the oldest age groups will have a major impact on future health care costs. We use current US Census Bureau projections for the growth of our oldest age groups to project future costs for Medicare, nursing homes, dementia, and hip fractures. Without major changes in the health of our older population, these health care costs will escalate enormously, in large part as a result of the projected growth of the "oldest old," those aged 85 years and above. Medicare costs for the oldest old may increase sixfold by the year 2040 (in constant 1987 dollars). It is unlikely that these projected increases in health care costs will be restrained solely by cost-containment strategies. Successful containment of these health care costs will be related to our ability to prevent and/or cure those age-dependent diseases and disorders that will produce the greatest needs for long-term care.

Aged↗