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Biomedical subjects

D E Harrison

Publications and source records attributed to D E Harrison.

At least 109 records · Page 6Linked to original sources
PubMed1985

Detection of islet cell surface antibodies using cloned beta cells and comparison of their incidence with that of islet cell cytoplasmic antibodies.

We have investigated the occurrence of islet cell antibodies in sera from newly-diagnosed patients with insulin-dependent diabetes mellitus (IDDM). For detection of islet cell surface antibodies (ICSA), cloned hamster beta cells (HIT-T15) were used and reaction of antibody with the beta cells was assessed by indirect immunofluorescence or by [125I]-protein A binding; the 2 procedures were shown to give good agreement. The use of HIT-T15 beta cells was validated by demonstration of good correlation between results obtained using HIT-T15 beta cells with those using dispersed rat islet cells. The presence of islet cell cytoplasmic antibodies (ICA) and complement fixing islet cell antibodies (CF-ICA) was assessed by conventional indirect immunofluorescence on unfixed, frozen sections of human pancreas. Of 33 sera from newly-diagnosed diabetics, 21 (64%) were positive for ICSA. In comparison, of 40 control sera only 7 (17%) were ICSA-positive. When the diabetic sera were assessed for cytoplasmic antibodies, 20 (60%) were positive for ICA of which half were also positive for CF-ICA. There were 6 IDDM sera which were negative for ICSA but positive for ICA: 7 of the ICSA-positive IDDM sera were negative for both ICA and CF-ICA. In 9 IDDM sera, positive reaction was obtained for all 3 types of antibody. All 9 sera positive for CF-ICA were also positive for ICSA. These data confirm the high incidence (greater than 80%) in IDDM sera of antibodies reacting with islet cells. Of these, the ICSA, which appear from the data to be distinct from ICA and CF-ICA, are possibly most relevant to the pathogenesis of IDDM.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Ultimate erythropoietic repopulating abilities of fetal, young adult, and old adult cells compared using repeated irradiation.

Erythropoietic repopulating abilities of fetal liver cells and young and old adult marrow cells were compared as follows: Equal numbers of cells from a donor of each age were mixed with a constant portion of cells pooled from genetically distinguishable competitors. These mixtures were transplanted into stem cell-depleted recipients, and the proportions of recipient hemoglobin that were donor type measured the relative effectiveness of early erythropoietic precursor cells from the various donors (Fig. 1). At intervals of 3-6 mo, recipients were sublethally irradiated, requiring a new round of competitive repopulation. When B6 mice were used as donors, with WBB6F1 competitors and recipients, the highest levels of stem cell activity were found using old donors (Tables I, III). This was true even with unirradiated, immune-competent W/Wv recipients (Table III). When donors and recipients were WBB6F1 hybrids, with B6 competitors, fetal cells initially gave higher levels of repopulating ability, and they were similar to the adult and old marrow cells after 400 d and after recovery from two sublethal irradiations (Table II). These effects were mostly insignificant and probably reflect small differences in initial stem cell concentrations that are brought out by the sensitivity of the competitive repopulation assay. Clearly, ultimate erythropoietic stem cell proliferative capacities did not decline as a result of the proliferation required between 15 d of fetal life and old age. Repopulating abilities of 12-d fetal liver cells were not detectable. We also showed that the proportions of newly synthesized hemoglobins made by the two types of stem cells in tetraparental mice remained nearly constant when tested at 3-d intervals over 30 d. Minimum numbers of stem cells producing erythrocytes over a single 3-d period were calculated as 62 and 128, but these are too low, since variances were similar in the tetraparental mice and in the F1 hybrid control. This contradicts the hypothesis that erythropoietic stem cells reserve limited proliferative capacities by proliferating one or a few at a time. We suggest that erythropoietic stem cells have essentially unlimited proliferative capacities and are found in approximately equal concentrations in the primary erythropoietic organs after 15 or 16 d of fetal life.

Aging↗
PubMed1984

Skin graft rejection in mice repopulated with marrow of the skin donor type: a Skn gene in a congenic line.

Genetically anemic W/Wv mice and lethally irradiated wild-type mice were cured and populated by grafted marrow cells from donor mice of three congenic lines that differed at non-H-2 histocompatibility loci. Tail skin from mice of the same congenic lines was grafted 3-4 weeks later. In two cases, the recipients behaved as expected, no longer rejecting skin syngeneic with the marrow graft that had repopulated them. However, B6-H-24c skin was rejected by WBB6F1-W/Wv mice that were cured with B6-H-24c marrow showing a mean survival time of 9.9 weeks. It was rejected somewhat faster, with a mean survival time of 5.9 weeks, by W/Wv mice cured with marrow from other types of donors. Results were more variable in lethally irradiated WBB6F1-+/+ recipients of B6-H-24c marrow, but they also rejected B6-H-24c skin. Both types of recipients remained chimeras after the skin was rejected, showing more than 90% of the B6-H-24c hemoglobin type. This is the first report of a Skn gene in a congenic line.

Animals↗
PubMed1984

Effects of food restriction on aging: separation of food intake and adiposity.

Restricted feeding of rodents increases longevity, but its mechanism of action is not understood. We studied the effects of life-long food restriction in genetically obese and normal mice of the same inbred strain in order to distinguish whether the reduction in food intake or the reduction in adiposity (percentage of fatty tissue) was the critical component in retarding the aging process. This was possible because food-restricted obese (ob/ob) mice maintained a high degree of adiposity. In addition to determining longevities, changes with age were measured in collagen, immune responses, and renal function. Genetically obese female mice highly congenic with the C57BL/6J inbred strain had substantially reduced longevities and increased rates of aging in tail tendon collagen and thymus-dependent immune responses, but not in urine-concentrating abilities. When their weight was held in a normal range by feeding restricted amounts, longevities were extended almost 50%, although these food-restricted ob/ob mice still had high levels of adiposity, with fat composing about half of their body weights. Their maximum longevities exceeded those of normal C57BL/6J mice and were similar to longevities of equally food-restricted normal mice that were much leaner. Food restricted ob/ob mice had greatly retarded rates of collagen aging, but the rapid losses with age in splenic immune responses were not mitigated. Thus, the extension of life-span by food restriction was inversely related to food consumption and corresponded to the aging rate of collagen. These results suggest that aging is a combination of independent processes; they show that reduced food consumption, not reduced adiposity, is the important component in extending longevity of genetically obese mice.

Adipose Tissue↗
PubMed1984

Effects of marrow donor and recipient age on immune responses.

This report describes treatments to restore diminished splenic immune responses of old mice. Lethal irradiation, followed by young bone marrow and infant thymus transplants, restored the T cell mitogen response and the antibody-forming cell response against sheep red blood cells in the old mice. Although old bone marrow cells restore these immune responses in young recipients, as well as do young bone marrow cells, old bone marrow in old recipients did not improve their levels of response. Longevities of old recipients with rejuvenated responses were not increased, and aging of tail tendon collagen was not affected. The effect of lethal irradiation before the marrow transplant was shown to be minimal, by the use of unirradiated old W-anemic recipients. Parabiosing young mice with old partners caused impairment of these two immune responses in the young partners without enhancing them in the old partners. The old partners did not have increased longevities. To explain these results, we suggest the following hypothesis: old bone marrow contains precursors that produce suppressive factors or cells when in an old environment but not when in a young environment. However, these factors, if allowed to develop in an old environment, can function in a young parabiosed partner.

Aging↗
PubMed1984

B lymphocyte precursors in embryonic and adult W anemic mice.

Mice homozygous for mutations at the dominant spotting or W locus on chromosome 5 have been extensively used as models of severe macrocytic anemia caused by defective hemopoietic stem cells. We examined cells of the developing B lineage in adult and embryonic W anemic mice both by phenotypic analyses and by three distinctly different functional assays for B lymphocyte precursors. Adult W/Wv mice had normal numbers of B cells in the spleen and bone marrow, and normal numbers of pre-B cells and cells identified by a monoclonal antibody directed to a B lineage cell surface antigen (14.8) in the bone marrow. Embryonic W/Wv and Wx/Wx mice had hypoplastic liver development at 16 days gestation with a corresponding reduction in absolute numbers of pre-B cells, 14.8+ cells, and clonable granulocyte-macrophage progenitor cells, although their frequencies were normal. As expected, spleen colony-forming units were greatly reduced both in absolute number and frequency. Adult bone marrow cells and fetal liver cells from W anemic mutants generated B cells in vitro as well as did cells from normal littermates, but W anemic cells failed to generate B lymphocytes as well in vivo. These observations likely reflect differences in precursor cells that contribute to B cell formation in these assays, and suggest that early B lineage precursors are reduced or defective in W anemic mice.

Aging↗
PubMed1983

Bone marrow toxicity induced by oral benzo[a]pyrene: protection resides at the level of the intestine and liver.

The Ah locus encodes a cytosolic receptor that regulates the induction of certain drug-metabolizing enzymes by polycyclic aromatic hydrocarbons such as benzo[a]pyrene. Some inbred mouse strains such as C57BL/6N have the high-affinity Ah receptor (Ahb/Ahb), others such as DBA/2N, the poor-affinity receptor (Ahd/Ahd). Presence of the high-affinity receptor leads to greater cytochrome P1-450 induction by benzo[a]pyrene; in turn, enhanced benzo[a]pyrene metabolism can result in more toxic intermediates or greater detoxication, depending upon the test system studied. Benzo[a]pyrene in the growth medium, in direct contact with cultured myeloid cells, is more toxic to C57BL/6N than DBA/2N cultured cells. Oral benzo[a]pyrene induces P1-450 (measured by benzo[a]pyrene trans-7,8-dihydrodiol formation determined by high-performance liquid chromatography) in C57BL/6N but not DBA/2N intestine and liver. In the bone marrow of oral benzo[a]pyrene-treated C57BL/6N and DBA/2N mice, the magnitude of P1-450 induction is about the same. WB/ReJ (Ahd/Ahd), C57BL/6J (Ahb/Ahb), or (WB/ReJ)(C57BL/6J)F1 (Ahb/Ahd) marrow was transplanted into lethally irradiated (WB/ReJ)(C57BL/6J)F1 mice. DBA/2J (Ahd/Ahd) marrow was transplanted into lethally irradiated BALB/cByJ (Ahb/Ahb) mice and vice versa. Mice having the Ahd/Ahd intestine and liver died in less than 3 weeks of benzo[a]pyrene feeding (120 mg/kg/day), irrespective of the source of transfused marrow. All the data are consistent with pharmacokinetic differences in the tissue distribution of benzo[a]pyrene: mice having the high-affinity receptor, and therefore the P1-450 induction process in the intestine and liver, are protected from oral benzo[a]pyrene-induced myelotoxicity.

Administration, Oral↗
PubMed1983

Long-term erythropoietic repopulating ability of old, young, and fetal stem cells.

It is possible that erythropoietic stem cells do not age. This would mean that stem cells from old donors can function as well as those from young or fetal donors. The competitive repopulation assay has been used to test long-term stem cell function by directly comparing how well competing stem cells repopulate a recipient and produce differentiated cell types. C57BL/6J (B6) mice were used as donors, while recipients and competitors were WBB6F1 hybrids with genetically distinguishable hemoglobin. Lethally irradiated young WBB6F1 recipients were given a mixture of 2.5 X 10(6) cells from B6 old marrow, young marrow, or fetal liver donors; each recipient also received a standard dose of 1 X 10(6) marrow cells from a pool of young WBB6F1 competitors. Surprisingly, the old marrow cells competed the best in repopulating the recipients. This pattern was maintained even after recovery from sublethal irradiation, a treatment that severely stresses stem cells. This stress was demonstrated when sublethal irradiation caused a 20-fold decline in repopulating ability measured using hemoglobin markers, and a 3- to 7-fold decline using chromosome markers. Stem cells from old marrow competed better than young or fetal cells in similar experiments using immunologically crippled recipients or using unirradiated W/Wv recipients that are immunologically intact. In both types of recipients, the advantage of old marrow cells again persisted after recovery from sublethal irradiation. Other genotypes were tested, and marrow cells from old B6CBAF1 donors competed better than those from young donors of that genotype. However, marrow cells from young CBA donors completed better than those from old CBA donors. These results support the hypothesis that stem cells do not age, and suggest that regulatory changes with age promote rapid stem cell repopulation in B6 and B6CBAF1 mice, but inhibit it in CBA mice.

Aging↗
PubMed1983

Physiological assays for biological age in mice: relationship of collagen, renal function, and longevity.

Tests of physiological changes with age are illustrated by collagen denaturation times of tail tendon fibers, and urine concentrating abilities; the tests are evaluated using the following four criteria: change with age, repeatability, relationship to other assays, and relationship to longevity. These tests usually showed highly significant changes with age when mice of different ages were compared for nine mouse genotypes, however neither appeared to be related to subsequent longevities of individual mice. When average values for eleven mouse genotypes were compared, the mean longevities of the genotypes were not significantly correlated with their mean collagen denaturation times or mean renal concentrating abilities, testes at two different ages. The relationships between all three factors--collagen denaturation times, urine concentrating abilities, and longevities--were tested in the same individuals for mice of six different genotypes at 600-700 days of age. Only one marginally significant correlation appeared out of 21 tested; this probably occurred by chance. We conclude that tail tendon collagen denaturation times and urine concentrating abilities change with age independently of each other; furthermore, these changes are unrelated to subsequent longevities, at least when linear relationships are tested. These data suggest that aging is timed by more than one mechanism and demonstrate that strong correlations with chronological age do not necessarily indicate that independent tests will be correlated with longevity or with each other.

Aging↗
PubMed1983

Decline in male mouse pheromone with age.

An age-related decline in urinary-borne pheromone was found in male C57BL/6J mice aged from 2 to 30 months. Pheromone activity, estimated by bioassay, declined sharply after about 10 months of age. Two other strains of mice tested (DBA/2J and CBA/HT6J) also appeared to show an age-related decline in pheromone activity. Within each strain, however, pheromone activity was consistently similar to or higher than that of the C57BL/6J male mice. The DBA/2J and BALB/cWt strains appeared to be high pheromone producers, and the C57BL/6J and CBA/HT6J strains, low producers. This report is the first demonstration of a decline with age in male mouse pheromone activity. This decline appears to be synchronized with the well-defined loss of reproductive function in female mice.

Aging↗
PubMed1982

Loss of stem cell repopulating ability upon transplantation. Effects of donor age, cell number, and transplantation procedure.

Long-term functional capacities of marrow cell lines were defined by competitive repopulation, a technique capable of detecting a small decline in repopulating abilities. There was little or no difference between cells from old and young donors, but a single serial transplantation caused a large decline in repopulating ability. Varying the numbers of marrow cells transplanted into the initial carrier from 10(5) to 10(7) did not alter the ability of the carrier's marrow cells to repopulate in competition with previously untransplanted cells. This ability was improved only in carriers that had received 10(8) marrow cells, although deleterious effects of transplantation were still present. These effects were not solely caused by cell damage from the transplantation procedure, because transplantation by parabiosis, or recovery from sublethal irradiation without transplantation, reduced repopulating abilities as much as transplanting 10(5) to 10(7) marrow cells. The transplantation effect also was not caused solely by irradiation, because the same effect appeared in unirradiated W/Wv carriers. The transplantation effect was more pronounced when donors were identified by hemoglobin type than by chromosome markers, implying that nonerythroid cell lines may be less affected by transplantation than erythroid precursor cells. When the effects of a lifetime of normal function and a single transplantation were compared, the latter caused 3-7 times more decline in repopulating abilities of phytohemagglutinin-responsive cell precursors, and at least 10-20 times more decline in erythroid cell precursors. Stem cell lines can be serially transplanted at least five times before losing their ability to repopulate and save lethally irradiated recipients or to cure genetically anemic mice. Therefore, if transplantation causes an acceleration of the normal aging process, these figures suggest that stem cells should be able to function normally through at least 15-50 life spans.

Aging↗
PubMed1982

Effects of Ca2+, calmodulin and cyclic AMP on the phosphorylation of endogenous proteins by homogenates of rt islets of langerhans.

Activation of Ca2+ -calmodulin- and cyclic AMP-dependent protein kinases has been suggested to be involved in stimulus-secretion coupling in the pancreatic beta-cell. To study the properties of suc kinases and their endogenous protein substrates homogenates of rat islets of Langerhans were incubated with [gamma-32P]ATP. Phosphorylated proteins were separated by sodium dodecyl sulphate polyacrylamide gel electrophoresis and detected by autoradiography. The phosphorylation of certain proteins could be enhanced by Ca2+ plus calmodulin or by cyclic AMP. The major effect of Ca2+ and calmodulin was to stimulate the phosphorylation of a protein (P53) of molecular weight 53,100 +/- 500 (n = 15). Maximum phosphorylation of protein P53 occurred within 2 min with 2 micrometers free Ca2+ and 0.7 micrometers calmodulin. Incorporation of label into protein P53 was inhibited by trifluoperazine or W7 but not by cyclic AMP-dependent protein kinase inhibitor. Phosphorylation of a proteins of similar molecular weight could be enhanced to a lesser extent in the absence of Ca2+ but in the presence of cyclic AMP and 3-isobutylmethylxanthine: this phosphorylation was blocked by cyclic AMP-dependent protein kinase inhibitor. Cyclic AMP also stimulated incorporation of label into polypeptides of molecular weights 55,000 and 70-80,000. The results are consistent with the hypothesis that protein phosphorylation mechanisms may play a role in the regulation of insulin secretion.

Adenosine Triphosphate↗
PubMed1982

Physiological and behavioral correlates of lifespan in aged C57BL/6J mice.

Physiological and behavioral measurements were made in a cohort of 29-month-old male C57BL/6J mice to determine whether any correlated significantly with lifespan. Significant linear relationships with lifespan were found among the physiological measures, including hematocrit and hemoglobin levels and collagen denaturation rate; however, body weight failed to be a significant predictor of survival. Among the behavioral variables studied, significant quadratic relationships with lifespan were found for exploratory activity and passive avoidance learning, while performance on a rotorod and a tightwire showed no significant relationships with lifespan. Through the use of multiple regression techniques, about one-third of the variance in lifespan could be explained by a combination of physiological variables, and about two-fifths could be explained by a combination of behavioral variables.

Aging↗
PubMed1982

Changes with age in renal function and morphology in C57BL/6, CBA/HT6, and B6CBAF1 mice.

Mice of the C57BL/6J and CBA/HT6J inbred strains and their F1 hybrid were investigated at 67, 202, 463, and 711 days of age to determine how genetic differences affected aging patterns of renal function and morphology. The three genotypes differed significantly in their body and kidney weights and their kidney to body weight ratios. These differences reflected functional capacities, and renal hypertrophy appeared to be an attempt to compensate for functional losses with age. The glomerular filtration rate (GFR) decreased in both inbred strains with age but remained constant in the F1 hybrid mice. There was a significant strain difference in GFR, but this difference disappeared when the GFR was considered in relation to the kidney weight. Thus the strain difference appeared to reflect differences in ability to compensate for loss of function by increasing kidney size. Osmolarities and sodium clearances decreased with age and increased with renal hypertrophy, but plasma levels were constant. Histopathological changes with age appeared to be correlated with functional changes.

Aging↗
PubMed1982

The effect of hypophysectomy on thymic aging in mice.

Surgical removal of the pituitary (hypophysectomy) followed by endocrine supplementation in middle-aged rats has been reported to reverse immunologic decline with age. We attempted to confirm and extend these reports by using a well-defined and readily available mouse model system. Hypophysectomy and endocrine supplementation in 8- to 9-mo-old C57BL/6J (B6) male retired breeder mice improved some, but not all, T dependent immune functions tested at 15 mo of age. In hypoxed mice, spleen cell proliferation in response to phytohemagglutinin (PHA) in vitro, and delayed type hypersensitivity (DTH) responses to sheep red blood cells (SRBC) measured by footpad swelling improved to levels shown by young controls. Direct anti-SRBC plaque-forming cell (PFC) responses by spleen cells, and serum agglutination responses against SRBC were not improved. Hypoxed mice had larger thymuses and much higher ratios of cortex-medulla areas than did age-matched controls. Hair regrowth after shaving was much faster in hypoxed mice. Nevertheless, hypophysectomy reduced mean and maximum longevities. These results conflict in several ways with the previously reported studies in rats, in which direct PFC responses and maximum longevities were improved by this treatment. There have been no previous studies of the effect of hypophysectomy and endocrine supplementation on thymic aging in mice, nor has it previously been reported that this treatment causes improvements in PHA and DTH responses and in thymic morphology. These effects show that at least some aging processes are reversible in aging individuals. They also suggest that hypophysectomy of middle-aged mice will be useful for studying neuroendocrine and thymic interactions that occur during the aging process.

Aging↗