PubMed Health⌕ Search

Biomedical subjects

J A Kramer

Publications and source records attributed to J A Kramer.

35 records · Page 2Linked to original sources
PubMed1997

RNA in spermatozoa: implications for the alternative haploid genome.

The presence of specific messenger RNAs in the nuclei of mature mammalian spermatozoa has been demonstrated by several independent laboratories. Others have suggested that various polymerases may also be active in mature spermatozoa. This has led to the notion that the 'sleeping' genome may not be so quiescent after all. The alternate use of somatic-like nucleosomal and haploid protamine packaging structures to assemble sperm chromatin and the ordered array of chromosomes within the mature human sperm nucleus support this view. This had led us to address the issue of whether a somatic-like organization of select regions of the paternal genome and the mRNAs present in spermatozoa were correlated. Results from this and other laboratories suggest that this in indeed the case. Potential roles for this novel packaging and the accumulation of transcripts within the mature human nucleus are discussed.

Animals↗
PubMed1996

Nuclear matrix interactions within the sperm genome.

Analysis of the haploid-expressed human PRM1 --> PRM2 --> TNP2 genic domain has revealed two regions of attachment to the sperm nuclear matrix. These sperm nuclear matrix attachment regions delimit the DNase I-sensitive domain of this haploid-expressed locus. The domain is intermediately associated with but not attached to the nuclear matrix. DNase I-sensitive genes within the mature sperm nucleus, such as protamine 1, protamine 2, transition protein 2, alpha-globin, and beta-actin, display this intermediate affinity for the sperm nuclear matrix. This may denote their role in templating the male genome prior to fertilization, thus ensuring the formation of a viable male pronucleus during early embryonic development.

Base Sequence↗
PubMed1996

Computer-assisted search for sites of nuclear matrix attachment.

This communication describes a useful approach for assessing the significance of the occurrence of multiple motifs within defined segments of the genome. Regions of potential biological importance are identified using various sequence motifs, and then the results are displayed as their cumulative statistically weighted distribution. We illustrate the utility of this strategy to the search for known nuclear matrix-associated regions by its application to the human beta-globin and other loci.

Algorithms↗
PubMed1995

A haploid expressed gene cluster exists as a single chromatin domain in human sperm.

Mammalian spermiogenesis is marked by the initial disruption of the nuclear-histone-DNA complex by the transition proteins for ultimate replacement with protamines. The genes for three of these low molecular weight basic nuclear proteins exist as a single linear array of PRM1, PRM2, and TNP2 on human chromosome 16p13.2. To begin to address the mechanism governing their transcriptional potentiation, a region of approximately 40 kilo-bases of the human genome encompassing these genes was introduced into the germ line of mice. Fluorescence in situ hybridization and Southern analysis showed that this segment of the human genome integrated into independent chromosomal sites while maintaining its fidelity. Transcript analysis demonstrated that the expression of the endogenous mouse protamine Prm1 and Prm2 genes as well as the mouse transition protein Tnp2 gene were expressed along with their human transgene counterparts. The pattern of expression of these transgenic human genes within this multigenic cluster faithfully represented that observed in vivo. In addition, all members of this transgenic gene cluster were expressed in proportions similar to those in human testis. Copy number-dependent and position-independent expression of the transgenic construct demonstrated that the corresponding biological locus was contained within this segment of the human genome. Furthermore, DNase I sensitivity established that in sperm the human PRM1-->PRM2-->TNP2 genic domain was contained as an approximately 28.5-kilobase contiguous segment bounded by an array of nuclear matrix associated topoisomerase II consensus sites. This is the first description of a multigenic male gamete-specific domain as a fundamental gene regulatory unit. A model of haploid-specific gene determination is presented.

Amino Acid Sequence↗
PubMed1994

Position 713 is critical for catalysis but not iron binding in soybean lipoxygenase 3.

The role of asparagine-713 in iron atom incorporation and catalysis in soybean lipoxygenase 3 was investigated using site-directed mutagenesis. A full-length cDNA for the lipoxygenase isoenzyme was obtained from a library derived from soybeans cv. Provar. Protein with native specific activity at pH 7.4 was obtained from expression in Escherichia coli. Two recent structure reports provided conflicting views about the participation of the side chain of asparagine-694 in the coordination of the iron atom required for catalysis by lipoxygenase 1. Oligonucleotide-directed mutagenesis was employed to modify residue 713 in lipoxygenase 3 which corresponds to asparagine-694 in the sequence of lipoxygenase 1. It was found that for enzyme expressed in bacteria, asparagine was not required for iron incorporation. Histidine, alanine, and serine substitutions for asparagine-713 all produced proteins that contained iron. The histidine mutant had specific activity and catalytic characteristics comparable to the wild-type enzyme. By contrast, the alanine- and serine-substituted lipoxygenases had no detectable catalytic activity. When oxidized by product, the histidine mutant also displayed the characteristic g6 signal of the soybean enzyme in its EPR spectrum. The possibilities that the residue at position 713 acts as a metal ligand, an acid-base catalyst, and a hydrogen bonding group are considered and discussed.

Asparagine↗
PubMed1993

Challenges and opportunities in the provision of long-term care.

The demands for long-term care are substantial and, given our nation's demographics, are likely to become a critical issue for the economy. Through employee assistance programs and the provision of long-term care benefits, employers are likely to see a substantial increase in individuals' concern for the provision of care.

Aged↗
PubMed1992

Regulating managed care firms: the Connecticut plan.

Virtually every state in the country, as well as the federal government, is either considering or has recently considered legislation to regulate utilization review/managed care companies. Despite the magnitude of this issue, few legislative bodies have expended the resources to study the form that regulation should take. Recently, Connecticut, which has seen considerable growth in utilization review within managed care programs that insure Connecticut residents, funded such a study. This article, authored by two of the study's participants, reviews the issues and explains the study's recommendations.

Attitude of Health Personnel↗
PubMed1991

Time management and leadership styles: an empirical study of long-term health care administrators.

Is there a relationship between the type of leadership style employed by long-term health care administrators and the effective use and management of time? This paper describes a 1989 study of 188 administrators of skilled nursing facilities and intermediate care facilities in Connecticut. Two self-rating instruments were employed: the Executive Time Management Inventory (Hartley, Kramer, et al.) and the LEAD-Self instrument (Hersey and Blanchard). Four hypotheses were tested at the .05 level of significance to examine relationships among time management, leadership style, size of facility, administrator experience, and cost factors. Statistical procedures included Pearson Product-Moment correlations, analysis of variance, t-tests, and partial correlations. Results of the study included (1) time management effectiveness increased as administrators gained more experience; (2) no significant relationship existed between type of leadership style and time management effectiveness; (3) women administrators perceived themselves as significantly more effective time managers than men did; (4) most health care administrators employed the same primary leadership style: "selling," which is defined as high relationship/high task; and (5) institutional size was not related to the time management effectiveness of the administrator. The findings have implications for pre-service and in-service training and for future studies in health administration education.

Connecticut↗
PubMed1975

Infants' development of object permanence: a refined methodology and new evidence of Piaget's hypothesized ordinality.

To investigate Piaget's theory of object concept development, a series of 6 tasks was administered in a combined longitudinal/cross-sectional design incorporating a number of methodological controls. The tasks spanned the entire sensorimotor period and included single versus sequential displacements combined with visible or invisible hidings. 36 infants from 5 to 32 months of age at initial testing were drawn equally from day-care and home settings. All infants received the 6 tasks during each of 3 testing sessions over a 6-month period. Clear evidence was obtained for task ordinality as proposed by Piaget, with ordinality coefficients ranging from .71 to .82 for the 3 testing sessions. Performance changes across the 3 sessions were also ordinal in 80% of the cases. Expected age, task, and session effects and accompanying interactions were also obtained.

Age Factors↗
PubMedDate not supplied

Extended analysis of the region encompassing the PRM1-->PRM2-->TNP2 domain: genomic organization, evolution and gene identification.

The human male haploid expressed protamine 1 (PRM1)-->protamine 2 (PRM2)-->transition protein 2 (TNP2) locus comprises a coordinately regulated multigenic domain. This region of 16p13.13 has been used as a model to address how the organization of genes and genic domains within the human genome may influence tissue specific gene expression. Toward this goal, we have completed an extensive computational and biological analysis of the region encompassing the PRM1-->PRM2-->TNP2 domain. These analyses have revealed the likely genesis of this domain. Interestingly, the SOCS-1 gene and an hnRNPC-class pseudogene lies just 3' of this domain. Regions of nuclear matrix attachment also mark these newly identified genes.

Chromosomal Proteins, Non-Histone↗