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Biomedical subjects

J D Hare

Publications and source records attributed to J D Hare.

At least 19 recordsLinked to original sources
PubMed2001

Diabetes in adolescent patients: diagnostic dilemmas.

The classification of diabetes mellitus by types (1 or 2), or by age of onset (juvenile or adult), helps to clarify many aspects of pathophysiology, prognosis, and therapy. However, less-commonly encountered patients, presenting in childhood or adolescence, may not fit neatly into one or the other group. These include teenagers who present with new-onset diabetes with ketoacidosis, but who are later able to be managed permanently as type 2 patients. Other adolescent patients present with only minimal glucose intolerance, then proceed to develop type 1 diabetes, with evidence of autoimmune etiology, after a variable number of years. Four patients are presented to illustrate these diagnostic dilemmas.

Adolescent↗
PubMed1998

Small tubes revisited.

We measured the peak inflation and end expiratory pressure at the proximal and distal ends of two sizes of tracheal tube in men and women receiving positive pressure ventilation. There was a statistically significant increase in proximal inflation pressure when the smaller size of tube (6.5 mm for men, 6.0 mm for women) was used. There was no increase in distal inflation or end expiratory pressures. Clinically satisfactory positive pressure ventilation was obtained when 6.0 and 6.5 mm tracheal tubes were used. The advantages and disadvantages of using small sizes of tracheal tube are discussed.

Adolescent↗
PubMed1992

Cell cycle analysis of asexual stages of erythrocytic malaria parasites.

Intra-erythrocytic Plasmodium species can be stained with the DNA binding dye, Hoechst 33342, and the distribution of DNA content determined for parasite populations by flow cytometric measurement of fluorescence. Analysis of this distribution will determine the parasitaemia (percentage of erythrocytes infected), and the percentages of trophozoite infected red blood cells, polyparasitized (trophozoite) red blood cells, and schizont/segmenter infected red blood cells. This analysis is based on the hypothesis that the asexual parasites cycle with single G1 period, and effectively, a single S phase with no significant G2/M period except at schizogony when the genome DNA content is equivalent to 8 N or higher, dependent on the species. Data are presented to support this model.

Animals↗
PubMed1987

Expression of polyomavirus virion proteins by a vaccinia virus vector: association of VP1 and VP2 with the nuclear framework.

The polyomavirus proteins VP1, VP2, and VP3 move from their cytoplasmic site of synthesis into the nucleus, where virus assembly occurs. To identify cellular or viral components which might control this process, we determined the distribution of VP1, VP2, and VP3 in a soluble fraction, a cytoplasmic cytoskeleton fraction, and a nuclear framework fraction of infected cells. All three proteins were detected in a detergent-extractable form immediately after their synthesis in polyomavirus-infected cells. Approximately 50, 25, and 40% of pulse-labeled VP1, VP2, and VP3, respectively, associated with the skeletal framework of the nucleus within 10 min after their synthesis. The remaining portion of each labeled protein failed to accumulate on the nuclear framework during a 40-min chase and was degraded. When expressed separately by recombinant vaccinia viruses, VP1 and VP2, but not VP3, accumulated on the nuclear framework. This association was not dependent on other polyomavirus proteins or viral DNA. The amount of total VP1 and VP2 which was bound to the nuclear framework approximated 45 and 20%, respectively. Indirect immunofluorescence demonstrated an exclusive nuclear localization of VP1 in situ. In coinfection experiments, a greater percentage of total VP2 and VP3 was bound to the nuclear framework of cells which cosynthesized VP1. These results indicate that although VP1 and VP2 can bind independently to the insoluble nuclear framework, the association of VP3 with this nuclear structure is promoted by the presence of VP1.

Animals↗
PubMed1986

Two-color flow-cytometric analysis of the growth cycle of Plasmodium falciparum in vitro: identification of cell cycle compartments.

A previous study (Hare JD, Bahler DW: J Histochem Cytochem 34:215, 1986) has shown that the flow cytometric analysis of acridine-orange-stained Plasmodium falciparum growing in vitro generates a complex two-color display, regions of which correlate with the major morphological stages. In this report, four cell cycle compartments (A-D) are defined by characteristic ratios of red and green fluorescence of cells distributed throughout the erythrocytic cycle as well as by the differential effects of several metabolic inhibitors. The primary characteristic of cells in compartment A is the significant increase in red fluorescence. Inhibition of DNA synthesis by either aphidicolin or hydroxyurea causes the accumulation of cells at the interface between compartments A and B, whereas n-butyrate prevents cells in compartment A from reaching the A-B interface. Cells in compartment A display a small increase in green fluorescence which is independent of DNA synthesis but is enhanced by n-butyrate treatment. Cells in compartment B display a continued increase in red fluorescence coupled with a significant increase in green fluorescence, reflecting the onset of DNA synthesis in compartment B. The transition to compartment C is more abrupt and is associated with a marked increase in green fluorescence and little increase in red fluorescence. Compartment D is characterized by an increase in red fluorescence and a continued rise in green fluorescence. It is postulated that these discontinuities in the two-color display reflect not only changes in the rates of RNA and DNA synthesis but also decondensation of parasite chromatin in compartment A as the organism prepares for DNA synthesis, and re-condensation in compartment D as the newly replicated chromatin prepares for segregation into merozoites. The method described promises to provide a sensitive and rapid technique to study the effects of various factors on the growth cycle of the parasite.

Animals↗
PubMed1986

Analysis of Plasmodium falciparum growth in culture using acridine orange and flow cytometry.

The growth of Plasmodium falciparum in cultures of human red blood cells was studied using acridine orange to stain RNA and DNA, followed by flow cytometric analysis. The cycle of the parasite is characterized by a period of growth, prior to initiation of DNA synthesis, in which a significant increase in red fluorescence is observed, with only a small change in green fluorescence. Following this phase, which is formally similar to the G1 period in mammalian cells, initiation of DNA synthesis is characterized by increases in green fluorescence. Sorting of cells from several regions of the two-dimensional display shows that the distribution of morphological stages correlates with differences in red and green fluorescence. The effect of aphidicolin on the growth cycle of the parasite was also studied.

Acridine Orange↗
PubMed1984

Flow cytometric analysis of blood cells stained with the cyanine dye DiOC1[3]: reticulocyte quantification.

The fluorescent dye 3,3'-dimethyloxacarbocyanine (DiOC1[3]) is taken up by all cells in mammalian blood which then fluoresce as follows: mature erythrocytes less than immature erythrocytes congruent to platelets less than leukocytes. A continuous fluorescence distribution can be generated for the red blood cells by flow cytometry and deconvolved into two arbitrary populations, mature and immature erythrocytes (mRBC and imRBC). This analysis mimics the established method of counting imRBC stained with the supravital dyes, new methylene blue, brilliant cresyl blue (BCB), and acridine orange (AO). However, the population of imRBC as quantified by DiOC1[3] fluorescence is a subset of reticulocytes (reticulocytes as determined by BCB assay). The advantages and disadvantages of using DiOC1[3], AO, or pyronine Y as reticulocyte stains are discussed.

Animals↗
PubMed1983

Analysis of malaria parasite-infected blood by flow cytometry.

The use of flow cytometry in the quantitative analysis of blood from mice infected with Plasmodium vinckei has been studied. Several fluorescent dyes responsive to cell membrane potential were screened and one dye, 3,3'-dimethyloxacarbocyanine (DiOC1(3) ), was chosen for further study. Mature red blood cells (mRBC), immature RBC (imRBC), and parasitized RBC (pRBC) could be recognized and counted in the flow cytometer. When infected blood was separated on a Percoll gradient and fractions analyzed by flow cytometry using DiOC1(3), distinct populations of pRBC were recognized, the frequency of which varied with density. These subpopulations could not be correlated with distinct morphologic stages but varied with the size or age of the growing parasite. Methods combining the use of DiOC1(3) with a DNA specific-dye, Hoechst 33342, are discussed as an approach to more complete analysis of the blood of malaria-infected animals.

Animals↗
PubMed1982

Mutation affecting late gene expression in polyoma virus maps in the late region.

A mutation in polyoma virus strain 3049 which results in the overproduction of capsid proteins has been mapped to the late region of the genome between the HindIII site at 45.0 map units and the BamHI site at 58.6 map units. This region contains the coding sequence for VP3 and a portion of VP2, but does not include the late promoters or the coding sequence for the late leaders. The possible role of VP2 or VP3 in the regulation of genetic expression in polyoma virus is discussed.

Base Sequence↗
PubMed1982

Charge microheterogeneity of the major capsid protein of polyoma virus.

The behavior in isoelectric focusing of the major capsid polypeptide VPI of several strains of polyoma virus was studied. Two previously recognized phenomena were reexamined, namely, (i) the separation of the VP1 polypeptide into multiple subspecies differing only slightly from each other in apparent isoelectric point and (ii) strain differences in the overall apparent net charge of the family of VP1 subspecies. It was found that the pattern of subspecies was reproducible when focusing was initiated from either the basic or acidic region of the gel, keeping the ampholyte mixture constant. However, individual subspecies were unstable, and labeled polypeptide could be shifted dramatically by either refocusing of separated subspecies or by altering the concentration of ampholytes. These findings suggest that protein-protein and protein-ampholyte interactions play an important role in the generation of this charge heterogeneity. The basis for the overall charge difference between the VP1 of 3049 virus and several other strains (lpD, lpS, ts59, and A2) was studied, using recombinant viruses constructed of specific sequences derived from 3049 and lpD genomes. The portion of the VP1 polypeptide carrying the altered charge could be mapped to the body of the molecule 3' to the HindIII site at 45.0 map units (3,918 base pairs). This clearly segregates the VP1 charge phenotype from the cyc phenotype of 3049 in which capsid proteins are overproduced and accumulate in the cytoplasm of infected cells.

Ampholyte Mixtures↗
PubMed1981

DNA synthesis and template activity in a mutant of polyoma virus with altered expression of late viral proteins.

The 3049 strain of polyoma virus overproduces late RNA and proteins. The synthesis and accumulation of virus DNA was measured in cells infected with 3049 and a wild-type virus, lpS, to assess the possible role of gene dosage in this phenomenon. The rate of incorporation of [3H]thymidine into the DNA of 3049 and lpS virus was shown to be identical. The number of genome copies per cell, determined by DNA-DNA reassociation kinetics, was found to be similar in either whole cell or Hirt extracts of cells infected with the two viruses. Viral transcription complexes were isolated by Sarkosyl extraction, and the specific transcriptional activity was measured by incorporation of [3H]UTP. The incorporation of [3H]UTP and the DNA content of transcription complexes were indistinguishable. These results suggest that overproduction of late RNA (and protein) by the 3049 virus is not due to either an increased number of viral genomes per cell or an increased fraction of genomes involved in transcription. These and other data (unpublished) support the conclusion that the altered phenotype is due to a posttranscriptional mechanism.

Animals↗
PubMed1978

The penetration of antibiotics into bacterial cells: significance to antimicrobial action.

The penetration of antibiotics into the microbial cell is reviewed from the standpoint of the structure and function of the several types of membranes which constitute permeability barriers to the passage of hydrophilic molecules. It is clear that little is actually known about the mechanisms by which the majority of antibiotics gain access to their site of action within the target cell. Sufficient evidece is at hand to indicate that resistance to several groups of antibiotics is determined by changes in the permeability of the cell membranes, the genes for which are often carried on R-plasmids. The importance of studies to determine the precise mechanisms by which each type of antibiotic permeates the membrane of the bacterial cell is stressed by a discussion of several approaches to enhancing antibiotic permeation through manipulation of either the drug or the target cell based on knowledge of the uptake mechanisms.

Aminoglycosides↗