Impaired glucose priming of insulin secretion from perfused pancreas in aged female rats.

Effects of age and glucose levels on insulin secretion and synthesis were studied in the perfused pancreas of young (2-month-old) and older (10-month-old) female Wistar rats. Insulin secretion induced by 16.7 mM glucose showed a triphasic pattern: an early spike and fall (first phase, 0-6 min), followed by a sustained gradual increase (second phase, 7-120 min) and a gradual decreased release thereafter (third phase, 121-360 min) during the perfusion period of 360 min. First and second phase insulin secretion, but not third phase, were lower in older rats than in young rats. Insulin synthesis in old rat pancreas perfused with 16.7 nM glucose for 360 min was much greater than that of young rats. Second phase insulin secretion was restored to comparable levels by 28 mM glucose in older rats. Repeated pulses of 28 mM glucose potentiated subsequent insulin secretion in young rats, but not in older rats. These findings provide further evidence that sensitivity to glucose in pancreatic B cells is altered by aging.

[An experimental study on the determinants to the effects of self-affirmation].

The purpose is twofold: first to examine whether an experience that affirms a valued aspect of the self eliminates the negativity of failure and second, to identify what is the most effective condition of self-affirmation. A 2 x 3 factorial design was employed: Immediately after having failed and prior to rating the beneficialness of failure experience, 72 subjects were allowed to affirm the real-self that they had built up, or the pseudo-self made by the experimenter. The situation of self-affirmation was (1) that subjects affirmed the self in private or (2) that the experimenter also affirmed the subject's self or (3) that the experimenter added information of another one who had the same aspect of self the subjects had affirmed. The self-affirmation effect was most clear-cut, when the real-self was affirmed, and was also affirmed by the experimenter. This effect was especially pronounced for high self-esteem subjects. Joint effects of high self-esteem, clearer real-self, and its publicity elevated level of self-affirmation.

[Acute myelogenous leukemia transformed from myelodysplastic syndrome with tetraploid chromosome constitution].

A 57-year-old female presented with general fatigue. She had neither lymphadenopathy nor hepatosplenomegaly. Laboratory data revealed anemia and leukopenia (1,500/microliters) with a differential count of 4.5% leukemic cells. The myelogram revealed 34.4% leukemic cells, of which diameter ranged from 20 to 28 microns. The diagnosis was acute myelogenous leukemia (FAB: M2) with myelodysplasia. Cytogenetic analysis revealed that the leukemic cells had chromosome abnormalities involving both diploidy and tetraploidy with structural rearrangement. Structural rearrangement included del(5) (q22q33), del(15) (q22q24), and t(3; 12) (q25;p13). Small dose aclacinomycin-A treatment was effective in reducing the number of leukemic cells in bone marrow, and both anemia and leukocytopenia were improved.

Effect of aging on the sensitivity of pancreatic beta-cells to insulin secretagogues in rats.

Glucose-stimulated insulin release from rat pancreas is known to be blunted by aging. In the present study, we examined the effect of aging on insulin release induced by various secretagogues using the isolated perfused pancreas of female rats. Insulin release from the perfused pancreas in response to 16.7 mM glucose in 8-month-old rats (older rats) was much less than that in 2-month-old rats (young rats). The first phase of insulin release after glucose stimulation was attenuated in older rats. The addition of 0.1 mM 3-isobutyl-1-methylxanthine (IBMX) potentiated glucose-induced insulin secretion in both groups of rats. However, the second phase of insulin secretion in older rats was lower than that in younger rats. The phorbol ester 12-O-tetradecanoyl phorbol ester (TPA, 200 nM) enhanced both the first and the second phases of insulin release induced by glucose in both groups of rats. The amount of first phase insulin release induced by TPA with glucose in young rats was greater than that in older rats, whereas the second phase of insulin release was similar in both groups of rats. On the other hand, tolbutamide (200 uM) similarly stimulated the first phase of insulin release in both age groups of rat. In addition, the amount of cumulative insulin secretion induced by tolbutamide during the second phase was slightly but significantly greater in older rats than in young controls. Insulin content in the pancreas was significantly greater in older rats than in young rats and increased after the stimulation with TPA and tolbutamide.(ABSTRACT TRUNCATED AT 250 WORDS)

Team effort: the nuclear medicine decision making process. Part II.

This two part article examines the nuclear medicine purchase of Baptist Memorial Hospital in Memphis, the largest private hospital in the nation. Part I (May 1991) focused on what their needs were. This concluding installment looks at the committee mechanism itself and the reasoning that went behind their decisions.

Gauging the heart of medical imaging. Probing the past, exploring the present, questioning the future.

In fifty years, will the radiologist be obsolete? If we listen closely, we can hear voices from the past whispering that same worry. We expect our fabulous machines to grow obsolete, but professions need not wither and fade if they evolve and innovate. Today, radiology can set foundations, begin to mold the future, and then await the show. For some of the main elements have not yet appeared or are not even being anticipated beyond the bend. As Arthur Clarke said, "the real future is not logically foreseeable." It lies a little past the impossible.

The last third. R&D: the return on our investment.

"The challenge is to balance what is good for the individual against what is in society's best interests without providing disincentives for product development." This quotation from a 1988 JAMA article by Peter Jacobson and John Rosenquist exploring contrast media issues goes beyond the usual scope of concern and also crystallizes why the low osmolar contrast agent (LOCA) controversy is so typical of the dilemmas that healthcare and society as a whole will continue to confront. The first two-thirds of this quotation presents a challenge that has been the subject of the LOCA debate for some time now: how to weigh the benefit to the individual versus the cost to society. The last third of this challenge acknowledges the importance of research and development, which has been largely ignored although it represents a vital ingredient for future healthcare improvements.

Differential sensitivity of pancreatic beta-cells to phorbol ester TPA and C-kinase inhibitor H-7 in nonpregnant and pregnant rats.

In order to elucidate the possible role of C-kinase in exaggerated insulin release in pregnancy, the effects of phorbol ester TPA and a C-kinase inhibitor H-7 were investigated using the isolated perfused pancreas from nonpregnant and pregnant rats. At the termination of perfusion, the insulin content of the perfused pancreas was determined to estimate insulin biosynthesis. Insulin release from the perfused pancreas was markedly augmented by 20 nM TPA in the presence of 4.4 mM glucose in pregnant rats, but not in nonpregnant rats. When glucose concentrations in the perfusate were raised to 16.7 mM, insulin release from the perfused pancreas was profoundly enhanced in pregnant rats. TPA further augmented insulin release, but the insulin content was not affected by TPA. In contrast to the considerable effect of TPA in the presence of 4.4 mM glucose, the potentiating effect of TPA on insulin release was rather weaker in pregnant than in non-pregnant rats in the presence of 16.7 mM glucose. The release of insulin induced by 16.7 mM glucose was inhibited by the addition of 100 microM H-7 in nonpregnant rats, whereas insulin release from pregnant rat pancreases was not altered. Thus, the effect of TPA and H-7 on insulin release can be more clearly observed in the beta-cells of nonpregnant rats than those of pregnant ones when maximal concentrations of glucose are used as a stimulant. Exaggerated insulin release caused by glucose in pregnancy may be due to already fully activated C-kinase in the beta-cells.