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Biomedical subjects

D L Adams

Publications and source records attributed to D L Adams.

50 records · Page 3Linked to original sources
PubMed1996

Postmetaphase nuclear formation: loss of a chromosomal epitope coincident with apparent chromatid coalescence.

Previously, we have conceptualized mitotic nuclear formation following metaphase as a morphogenic process and have suggested that sets of chromatids, after separation from a metaphase plate, can be thought of as prenuclei. Such structures can be grouped temporally as either early or late prenuclei based on morphologic, morphometric and density characteristics. Sequential ordering of early prenuclei is of particular interest because it reveals that condensed chromatids coalesce with the resulting formation of a unique chambered structure. In this paper we describe data obtained with a newly raised monoclonal antibody (mAb-2) that initially recognizes an epitope(s) on metaphase chromosomes. Light and confocal fluorescent microscopy of early prenuclei reveal that the chromosomal epitope can no longer be detected about chromatids after their apparent coalescence. Immunoblot analysis of dispersed polypeptides of metaphase plates and early prenuclei indicates that the major protein antigens recognized by mAb-2 have apparent molecular masses of approximately 106000 and 80500 and that each is likely composed of multiple charge isomers. A dual fluorescent analysis using mAb-2 and high-titer anti-lamin B serum provides additional evidence that chromatid coalescence is a separate, early event that precedes nuclear lamina formation.

Animals↗
PubMed1996

Cardiac surgical conditions induced by beta-blockade: effect on myocardial fluid balance.

BACKGROUND: Both crystalloid and blood cardioplegia result in cardiac dysfunction associated with myocardial edema. This edema is partially due to the lack of myocardial contraction during cardioplegia, which stops myocardial lymph flow. As an alternative, acceptable surgical conditions have been created in patients undergoing coronary artery bypass operations with esmolol-induced minimal myocardial contraction. We hypothesized that minimal myocardial contraction during circulatory support using either standard cardiopulmonary bypass (CPB) or a biventricular assist device would prevent myocardial edema by maintaining cardiac lymphatic function and thus prevent cardiac dysfunction. METHODS: We placed 6 dogs on CPB and 6 dogs on a biventricular assist device and serially measured myocardial lymph flow rate and myocardial water content in both groups and preload recruitable stroke work only in the CPB dogs. In all dogs we minimized heart rate with esmolol for 1 hour during total circulatory support. RESULTS: Although myocardial lymph flow remained at baseline level during CPB and increased during biventricular assistance, myocardial water accumulation still occurred during circulatory support. However, as edema resolved rapidly after separation from circulatory support, myocardial water content was only slightly increased after CPB and biventricular assistance, and preload recruitable stroke work was normal. CONCLUSIONS: Our data suggest that minimal myocardial contraction during both CPB and biventricular assistance supports myocardial lymphatic function, resulting in minimal myocardial edema formation associated with normal left ventricular performance after circulatory support. The concept of minimal myocardial contraction may be a useful alternative for myocardial protection, especially in high-risk patients with compromised left ventricular function.

Adrenergic beta-Antagonists↗
PubMed1995

Normothermic continuous antegrade blood cardioplegia does not prevent myocardial edema and cardiac dysfunction.

BACKGROUND: Normothermic continuous blood cardioplegia (BC) has been proposed to completely protect the myocardium during cardiac surgery. However, previous work from our laboratory suggests that BC could cause myocardial edema that produces cardiac dysfunction. The purpose of this present study was to evaluate the impact of BC on myocardial fluid balance and left ventricular function. METHODS AND RESULTS: In 11 dogs, myocardial water content (MWC) was determined by microgravimetry. Myocardial lymph flow rate was measured after cannulation of the major prenodal cardiac lymphatic. Preload recruitable stroke work (PRSW) was calculated by sonomicrometry and micromanometry. The dogs were placed on normothermic cardiopulmonary bypass (CPB), and BC was delivered at either 80 to 90 mm Hg (BChigh; n = 6) or 40 to 50 mm Hg (BClow; n = 5) for 1 hour. Coronary sinus lactate and oxygen saturation monitoring demonstrated ischemia avoidance. BC was associated with substantial myocardial lymph flow rate decrease (P < .05) and myocardial edema development in both groups. MWC increased from 76.0 +/- 1.9% to 79.2 +/- 1.7% (P < .05) after 10 minutes of BChigh and from 75.9 +/- 0.6% to 78.9 +/- 1.4% (P < .05) after 30 minutes of BClow. PRSW decreased to 63 +/- 19% (BChigh) and 69 +/- 15% of control (BClow) at 30 minutes after CPB (P < .05). Myocardial lymph flow rate increases of threefold to fourfold that of control (P < .05) resulted in significant myocardial edema reduction associated with PRSW improvement to 71 +/- 17% (BChigh) and to 78 +/- 11% (BClow) at 2 hours after CPB. CONCLUSIONS: We conclude that BC is associated with compromised cardiac function despite ischemia avoidance. This cardiac dysfunction is due to myocardial edema caused by the combination of increased myocardial microvascular fluid filtration and decreased myocardial lymph flow rate during BC.

Animals↗
PubMed1994

Effect of online literature searching on length of stay and patient care costs.

PURPOSE: To examine the associations between (1) the economic indicators of hospital costs, charges, and length of stay (LOS) for inpatient cases and (2) the use of MEDLINE searches for such cases. METHOD: An outcome-based, objective, prospective study with an economic evaluation was conducted from September 1989 to September 1990 at three metropolitan Detroit teaching hospitals representing both allopathic and osteopathic care. The study consisted of (1) 192 test cases, derived from a consecutive sample of inpatients of all ages for whom MEDLINE searches were requested at the participating medical libraries, and (2) 10,409 control cases, which were of the same diagnosis-related groups (DRGs) as the test cases but did not involve identified MEDLINE searches. Statistical analysis included the use of multivariate analyses of variance and correlation coefficients. Comparisons of cases were made on case-by-case and DRG bases regarding total patient costs, charges, and lengths of stay for cases with or without MEDLINE searches. RESULTS: The test cases were found to have a higher severity of illness. Among test cases, statistically significant relationships existed between (1) hospital expenses and LOS and (2) hospital expenses and the timing of the search during hospitalization when controlling for LOS. When cases were matched for DRG and LOS, the cases with early searches (i.e., conducted during the first half of hospitalization) had significantly lower expenses. CONCLUSION: Of the test-case patients (for whom MEDLINE searches were conducted during hospitalization), those whose searches were conducted earlier had statistically significantly lower costs, charges, and lengths of stay than those whose searches were conducted later.

Adolescent↗
PubMed1991

Caring for the acute myocardial infarction patient: a nursing perspective.

Cardiac nursing is nearly 30 years old. Changes in the role of cardiac nursing have directly corresponded to the three distinct medical phases of care for the acute myocardial infarction patient--arrhythmia detection, pump failure, and limiting infarct size. Nursing care delivery in the cardiac setting, the cardiac patient, and the role of the cardiac nurse each have undergone changes over the years, which together has provided a challenge to health care delivery. Future effects of technological and pharmacologic advances, social changes, and nursing professional practice issues on cardiac care delivery are imperative to consider as health care moves into the 1990s.

Forecasting↗
PubMed1978

Regulation of an aspartyl-tRNA species in BHK cells in culture and in solid tumor form. II. The effect of different sera on aspartyl-tRNA in culture.

In normal tissues aspartyl tRNA is present in 3 separable components by RPC-5-chromatography, 2 small and early eluting peaks and a major component designated rRNAAspIII. A late eluting peak, tRNAAspIV has also been found in many tumors of human and animals origin, and in BHK 21/13 cells grown in culture, where 27% or more of the total aspartate acceptance occurs in this peak. In contrast, normal tissue studied, i.e., hamster liver or kidney, exhibits less than 2.0% of the total aspartyl tRNA as the late eluting tRNAAspIV. Increasing the level of fetal calf serum in the medium from 5 to 15% resulted in a change from 0.79 to 1.83 in the ratio of tRNAAspIII--tRNAAspIV in BHK cells. Utilizing sera from different species, the percentage of tRNAAspIV was found to vary between 26.8 and 66.0% while the combined percentages of tRNAAspIII and tRNAAspIV varied between 59.5 and 80.8%. It appears that the increased tRNAAspIII was derived from tRNAAspIV and vice versa indicating that there may be a close structural relationship between tRNAAspIII and tRNAAspIV. It was also observed that BHK tumor cells or ascitic fluid enhanced the appearance of tRNAAspIV in normal host liver.

Animals↗
PubMed1976

Extended x-ray-absorption fine structure-Auger process for surface structure analysis: Theoretical considerations of a proposed experiment.

A method for surface structure analysis is proposed. The proposed process combines x-ray photoabsorption and Auger electron emission. The extended x-ray-absorption fine structure, occurring for photon energies above an atomic absorption edge, contains structural information of the microscopic environment due to the coupling of the photoelectron final state with the atomic initial state. Measurement of the variations in the intensity of particular Auger lines, as a function of the incident radiation energy, provides a surface sensitive measure of the photoabsorption cross section in the media. Theoretical considerations of the physical processes underlying the proposed experiment and its feasibility, and a discussion of background contributions are presented.

Journal Article↗
PubMed1971

Compound stimulus control by discriminative stimuli associated with high and moderate response rates.

Four rats received water on a fixed-ratio schedule for lever pressing in the presence of a tone (or light) stimulus and on a variable-interval schedule in the presence of a light (or tone) stimulus. Following stabilization of a high response rate during the fixed-ratio component and a moderate response rate during the variable-interval component, brief periods with the light and tone presented simultaneously but with no responses reinforced were inserted into the regular training schedule. Response rates during the compound stimuli were intermediate between the response rates controlled by the individual fixed-ratio and variable-interval associated stimuli.

Animals↗
PubMedDate not supplied

Rapid identification of ocular dominance columns in macaques using cytochrome oxidase, Zif268, and dark-field microscopy.

Strabismus induces an abnormal pattern of alternating light and dark columns of cytochrome oxidase (CO) activity in macaque striate cortex. This pattern may arise because visual perception is suppressed in one eye to avoid diplopia. To test whether CO activity is reduced in the ocular dominance columns of the suppressed eye, we performed monocular enucleation to co-label the ocular dominance columns with Zif268 immunohistochemistry in seven exotropic adult Macaca fascicularis. This approach was unsuccessful, for two reasons. First, Zif268 yielded inconsistent labelling, that was usually greater in the enucleated eye's ocular dominance columns, but was sometimes greater in the intact eye's columns. Therefore, Zif268 was not a reliable method for identifying the ocular dominance columns serving each eye. Second, in three control animals we found that a brief survival period following monocular enucleation (needed for Zif268 levels to change) was long enough to alter CO staining. For example, a survival time of only 3 h was sufficient to induce CO columns, indicating that the activity of this enzyme fluctuates more rapidly than realized previously. Independent of these findings, we have also discovered that acute monocular enucleation produces a vivid pattern of ocular dominance columns visible in unstained or CO-stained sections under dark-field illumination. The ocular dominance columns of the acutely enucleated eye appear dark. This was verified by labelling the ocular dominance columns with [3H]proline. Dark-field illumination of the cortex after acute monocular enucleation offers a new, easy method for identifying the ocular dominance columns in macaques.

Animals↗