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Biomedical subjects

D C Adams

Publications and source records attributed to D C Adams.

At least 19 recordsLinked to original sources
PubMed2001

A model for phylogenetic inference using structural and chemical covariates.

We investigated whether or not evolutionary change in DNA sequence data was homogeneous across different classes of base pairs. DNA sequences for eight protein-coding mitochrondrial genes were obtained for 38 vertebrate taxa from GenBank. Each nucleotide site in the alignment was classified according to a number of covariates, including its codon position, genetic code degeneracy, and hydrophobicity. The evolutionary transition matrix for each base was estimated by tracing implied character changes under parsimony on a known phylogenetic tree. Canonical variates analyses of the inferred transition matrices were performed for each gene to determine whether or not different classes of bases behaved similarly. We found five distinct clusters of transition matrices that could be roughly defined by combinations of codon position and degeneracy. This pattern was consistent among all genes. A stochastic model of rate variation based on the interaction of the covariates was developed to assess the statistical significance of the clusters. The five-group classification was found to explain significantly more sequence variation than did a codon only classification, a codon degeneracy classification, or a codon and degeneracy classification. The same five-group classification was found for all genes tested, suggesting a common process underlying the molecular evolution of the mitochondrial genome. These results confirm that there are classes of base pairs that evolve differently, and suggest that models of sequence evolution that incorporate covariate information may be useful in developing nucleotide substitution models that more accurately reflect evolutionary history.

Animals↗
PubMed2001

Effects of stable flies (Diptera: Muscidae) on weight gains of grazing yearling cattle.

Differences in weight gains caused by stable flies, Stomoxys calcitrans (L.), on grazing yearling steer/calves averaged 0.2 kg per steer in a 3-yr study on canyon range pastures in West Central Nebraska, Stable fly numbers averaged 0.85 per front leg on treated calves and 3.64 per front leg on control calves. In 2 of the 3 yr after the grazing trials were completed, the calves were placed in a feedlot and fed a finishing ration. Compensatory gain did not occur in the feedlot after the stable fly stress was removed.

Animals↗
PubMed2000

Ecological character displacement in Plethodon: biomechanical differences found from a geometric morphometric study.

Ecological character displacement describes a pattern where morphological differences between sympatric species are enhanced through interspecific competition. Although widely considered a pervasive force in evolutionary ecology, few clear-cut examples have been documented. Here we report a case of ecological character displacement between two salamander species, Plethodon cinereus and Plethodon hoffmani. Morphology was quantified by using linear measurements and landmark-based geometric morphometric methods for specimens from allopatric and sympatric populations from two geographic transects in south-central Pennsylvania, and stomach contents were assayed to quantify food resource use. Morphological variation was also assessed in 13 additional allopatric populations. In both transects, we found significant morphological differentiation between sympatric populations that was associated with a reduction in prey consumption in sympatry and a segregation of prey according to prey size. No trophic morphological or resource use differences were found between allopatric populations, and comparisons of sympatric populations with randomly paired allopatric populations revealed that the observed sympatric morphological differentiation was greater than expected by chance. The major trophic anatomical differences between sympatric populations relates to functional and biomechanical differences in jaw closure: sympatric P. hoffmani have a faster closing jaw, whereas sympatric P. cinereus have a slower, stronger jaw. Because salamanders immobilize prey of different sizes in different ways, and because the observed sympatric biomechanical differences in jaw closure are associated with the differences in prey consumption, the observed character displacement has a functional ecological correlate, and we can link changes in form with changes in function in this apparent example of character displacement.

Analysis of Variance↗
PubMed2000

Assessing quality of life in patients with head and neck cancer: cross-validation of the European Organization for Research and Treatment of Cancer (EORTC) Quality of Life Head and Neck module (QLQ-H&N35).

OBJECTIVE: To evaluate the reliability and validity of a new, disease-specific quality-of-life measure for patients with head and neck cancer: the European Organization for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire--QLQ-H&N35. DESIGN: Cross-sectional study using questionnaire data and medical chart review. SETTING: Academic tertiary care otolaryngology clinic. PARTICIPANTS: One hundred twenty ambulatory patients, including 30 patients with advanced head and neck cancer in each of the following stages of treatment: (1) prior to treatment, (2) during active treatment, (3) within 6 months of completing treatment, and (4) more than 6 months after completing treatment. In addition, (5) a comparison group of 40 patients without malignant disease was included (total sample, N = 160). MAIN OUTCOME MEASURES: Scores on EORTC Quality of Life Core Questionnaire (QLQ-C30) and head and neck module (QLQ-H&N35), Profile of Mood States, and Impact of Events Scale. RESULTS: The QLQ-H&N35 demonstrated acceptable reliability (internal consistency). It successfully discriminated between cancer patients and the comparison group, and among subgroups of cancer patients at different phases of treatment (construct validity). The instrument was sensitive to the effects of radiation treatment and to site of disease. Its low-to-moderate correlations with the EORTC core questionnaire indicated that the QLQ-H&N35 provided unique information (discriminant validity). Scores were significantly associated with a number of demographic variables. CONCLUSION: Results support the use of this disease-specific measure to assess quality of life among patients with advanced head and neck cancer.

Activities of Daily Living↗
PubMed2000

Coping with head and neck cancer during different phases of treatment.

BACKGROUND: Little is known about how patients cope with head and neck cancer despite its devastating impact on basic functioning. This study examined coping patterns among patients at different phases of illness. METHODS: Participants were 120 patients with advanced disease, who were grouped according to the following phases of illness: (1) pretreatment, (2) on treatment, (3) <6 months after treatment, and (4) >6 months after treatment. Coping was assessed with the COPE questionnaire, and outcome measures assessed general distress (Profile of Mood States) and illness-specific distress (Impact of Events Scale). RESULTS: Use of specific coping responses differed among the groups. Denial (p <.05), behavioral disengagement (ie, giving up or withdrawing, p <.05), suppression of competing activities (ie, focusing exclusively on the illness, p <.01), and emotional ventilation (p <.10) were most characteristic of patients who were receiving or had recently completed treatment. There were no differences in flexibility of coping or overall effort expended, but patients who were on treatment or who had recently completed treatment used the greatest number of strategies. Generally, denial, behavioral disengagement, and emotional ventilation were associated with greater distress. CONCLUSIONS: Results suggest that phase of illness may be important in shaping patients' responses to life-threatening illness.

Adaptation, Physiological↗
PubMed2000

A multidimensional measure of religious involvement for cancer patients: the Duke Religious Index.

Despite increasing interest in the relationship between religious involvement and health outcomes for cancer patients, research has been limited by the lack of appropriate measures. Few of the many instruments available are well suited to cancer patients. The current study examined the psychometric properties of one recently developed measure, the Duke Religious Index (DRI), which assesses several aspects of religious involvement. The DRI was evaluated in two distinct samples: 104 cancer patients receiving treatment at a bone marrow transplantation program and 175 gynecology clinic patients. The instrument demonstrated good internal consistency (coefficient alphas 0.87-0.94). Moderate to high correlations with other measures of religiosity provided support for convergent validity. Modest relationships with other measures commonly used in psychosocial oncology (e.g., optimism, social support, purpose in life) indicated that the instrument provides unique information (all rs's < 0. 42). Small relationships with social desirability response bias, negative affect, and relationship cohesion further supported the divergent validity of the instrument (all rs's < 0.22). The DRI was significantly associated with demographic characteristics but not with medical variables. Findings support the value of the DRI for use in oncology settings.

Adult↗
PubMed2000

Arterial blood pressure and heart rate discrepancies between handwritten and computerized anesthesia records.

UNLABELLED: Previous publications suggest that handwritten anesthesia records are less accurate when compared with computer-generated records, but these studies were limited by small sample size, unblinded study design, and unpaired statistical comparisons. Eighty-one pairs of handwritten and computer-generated neurosurgical anesthesia records were retrospectively compared by using a matched sample design. Systolic arterial pressure (SAP), diastolic arterial pressure (DAP), and heart rate (HR) data for each 5-min interval were transcribed from handwritten records. In computerized records, the median of up to 20 values was calculated for SAP, DAP, and HR for each consecutive 5-min epoch. The peak, trough, standard deviation, median, and absolute value of the fractional rate of change between adjacent 5-min epochs were calculated for each case. Pairwise comparisons were performed by using Wilcoxon tests. For SAP, DAP, and HR, the handwritten record peak, standard deviation, and fractional rate of change were less than, and the trough and median were larger than, those in corresponding computer records (all with P: < 0.05, except DAP median and HR peak). Considering together all the recorded measurements from all cases, extreme values were recorded more frequently in computerized records than in the handwritten records. IMPLICATIONS: The discrepancies between handwritten and computerized anesthesia records suggest that some of the data in handwritten records are inaccurate. The potential for inaccuracy should be considered when handwritten records are used as source material for research, quality assurance, and medicolegal purposes.

Adolescent↗
PubMed2000

Incidence of atrial fibrillation after mild or moderate hypothermic cardiopulmonary bypass.

OBJECTIVES: Atrial fibrillation remains a significant source of morbidity after coronary artery bypass grafting (CABG). Whether cardiopulmonary bypass (CPB) temperature influences the occurrence of postoperative atrial fibrillation in CABG patients has not been specifically examined. In the present study, we reviewed postoperative data from patients who were prospectively randomized to mild or moderate hypothermic CPB for elective CABG to determine the incidence of postoperative atrial fibrillation. DESIGN: Randomized, single center, observational study. SETTING: Tertiary university medical center. PATIENTS: Adults undergoing elective CABG surgery. INTERVENTIONS: Enrolled patients were prospectively randomized to mild (34 degrees C [93.2 degrees F]) or moderate (28 degrees C [82.4 degrees F]) hypothermic CPB. MEASUREMENTS AND MAIN RESULTS: The incidence of postoperative atrial fibrillation was determined by review of ICU and hospital records. There was a significantly higher incidence of atrial fibrillation in the moderate compared with the mild hypothermic CPB group. Patients who had postoperative atrial fibrillation were significantly older than those without atrial fibrillation. Furthermore, a significant increase in the relative risk of developing postoperative atrial fibrillation was found for both age and CPB temperature. CONCLUSIONS: Our results indicate that the temperature of systemic cooling during CPB is an important factor in the development of atrial fibrillation after CABG surgery. In addition, this study confirms that increasing age is a significant determinant of postoperative atrial fibrillation.

Adult↗
PubMed1999

Safety and efficacy of fixed-dose heparin in carotid endarterectomy.

OBJECTIVE: Although fixed dosage of heparin is frequently used during vascular surgery, there are very few studies that document the appropriateness of this type of dosing. We have undertaken a prospective study to determine the physiological response to a fixed dose of heparin, using a conventional measure of anticoagulation, and have correlated this measure with complications. METHODS: We studied 140 consecutive patients undergoing elective carotid endarterectomy. Serial activated clotting times (ACT values) were obtained in duplicate before administration of heparin, 15 minutes after application of a carotid artery cross-clamp, and 1 hour after administration of 5000 U of heparin by intravenous bolus. Postoperatively, patients were assessed for new neurological deficits (transient ischemic attack and stroke) and neck hematomas. A battery of neuropsychometric tests was performed in 49 patients at baseline and on the day after carotid endarterectomy to identify subtle new neurological deficits. RESULTS: ACT values were found to be highly reproducible, with less than a 1.5% difference between duplicate baseline samples. Although all patients received 5000 U of heparin, the dose received per kilogram of body weight varied considerably (44-116 U/kg), as did ACT values at both 15 minutes (178-423 s) and 1 hour (173-390 s). Nevertheless, there was a significant correlation between heparin dose per kilogram and ACT values at 15 minutes (r = 0.45) and at 1 hour (r = 0.38) postinfusion, as well as ACT ratios (final ACT/initial ACT) at 15 minutes (r = 0.43) and at 1 hour (r = 0.34) after heparin bolus. Eight patients (5.7%) developed postoperative wound hematomas, one of which (0.7%) required reoperation. No patient had a stroke, but one patient had a transient ischemic attack, and 19 (39%) of 49 patients demonstrated significant early postoperative neuropsychometric deficits. Although the incidence of neck hematoma was not influenced by the heparin dose (P = 0.23), the ACT value at 15 minutes (P = 0.71) or 1 hour (P = 0.61), or the ACT ratio (P = 0.68), the only severe hematoma requiring reoperation occurred when the maximal ACT value was more than 400 seconds. Although performance on neuropsychometric tests did not appear to be statistically influenced by heparin dosing, the ACT value, or the degree of ACT elevation, there was a trend for deficits to be associated with lower heparin doses. CONCLUSION: Fixed heparin dosing achieves safe and efficacious anticoagulation in the great majority of patients having carotid endarterectomy, with 5000 U expected to result in 15-minute and 1-hour ACT values of 175 to 425 seconds and 170 to 390 seconds, respectively. Although weight-based heparin dosing may reduce the incidence of subtle complications (hematoma formation or decline on neuropsychometric tests) and may result in more predictable 15-minute and 1-hour ACT values (85 U/kg; 225-375 and 200-340 s, respectively), no statistically compelling clinical advantage could be demonstrated. Therefore, either weight-based or fixed dosing is acceptable, with both obviating the need for routine pre-clamp ACT confirmation, thereby saving operative time and expense.

Adult↗
PubMed1999

Effects of supplementation of organic and inorganic combinations of copper, cobalt, manganese, and zinc above nutrient requirement levels on postpartum two-year-old cows.

The objective of this study was to determine whether a combination of Cu, Co, Mn, and Zn in an organic or inorganic form fed at higher than nutrient recommendations for 2-yr-old cows from calving to breeding would affect pregnancy rate, calving date, calf performance, and cow liver and serum mineral concentrations. Crossbred 2-yr-old cows were used after calving in 1994 (n = 127) and 1995 (n = 109). Cows were blocked by calving date to one of three treatments: 1) no supplemental minerals (CTL), 2) organic minerals (ORG), or 3) inorganic minerals (ING). Minerals were fed for the same daily intake for both organic and inorganic treatments: Cu (125 mg), Co (25 mg), Mn (200 mg), and Zn (360 mg). Cows were individually fed a mineral-protein supplement with grass hay from calving (February-March) to before breeding (May 15). Hay intakes were calculated using chromium oxide boluses to determine fecal output. Fecal excretion of minerals was calculated following trace element analysis of feces. Liver biopsies were obtained before calving, after calving (start of supplementation), at the end of supplementation, and in midsummer. Over 2 yr, more cows did not become pregnant (P < .01) in ORG (11/78) and ING (11/78) treatments than in CTL (0/80) treatments. A treatment x year interaction was found for day of conception. Cows in the ORG group conceived later (P < .01) than cows in the ING or CTL groups in 1994. In 1995, there was no difference (P > .10) in day of conception among groups. Liver Zn and Mn concentrations were not different (P > .10) and Cu concentrations increased (P < .01) for the ORG and ING groups. Cows in the ORG and ING groups had higher (P < .01) concentrations of Cu, Mn, and Zn in the feces than the CTL cows. Trace elements in the feces did not differ for ORG and ING groups. Results indicate that combinations of Cu, Co, Mn, and Zn fed at higher levels than are required reduced reproductive performance.

Animal Feed↗
PubMed1999

Adenosine-induced transient asystole for management of a basilar artery aneurysm. Case report.

Advances in anesthetic and surgical management, such as induced deep hypothermic circulatory arrest and application of temporary clips, have improved outcome for patients with basilar artery aneurysms. Nonetheless, these techniques are associated with significant risks. The authors report a case in which three transient periods of cardiac asystole were induced during basilar artery aneurysm surgery. Adenosine-induced asystole facilitated the safe clipping of the aneurysm by producing consistent periods of profound hypotension and collapse of the aneurysm without the need for temporary clipping. This technique provided unencumbered identification of perforating arteries, precise definition of the local anatomy, and an ideal environment for the safe placement of the aneurysm clip.

Adenosine↗
PubMed1998

Evidence for unconscious memory processing during elective cardiac surgery.

BACKGROUND: Many anesthetic drugs have been shown to disrupt conscious recall (explicit memory) in volunteers. However, unconscious processing (implicit memory) of intraoperative auditory material may occur during general anesthesia and may provide an opportunity for intraoperative therapeutic intervention. In this study, we examined patients undergoing elective cardiac surgery for evidence of intraoperative implicit and explicit memory. METHODS AND RESULTS: Twenty-five subjects provided written informed consent and underwent general anesthesia and cardiopulmonary bypass for cardiac surgery. During the operation, patients were randomized to receive 1 of 2 different audiotapes of associated word pairs. Postoperatively, a blinded observer conducted a standardized interview to determine the extent of intraoperative implicit and explicit memory. With the use of free association, significant intraoperative implicit memory was found. In contrast, no patient had spontaneous or directed recall of intraoperative events, and we did not find evidence of intraoperative explicit memory with a recognition task. CONCLUSIONS: Patients undergoing general anesthesia for cardiac surgery were reliably able to reinforce associations between word pairs solely on the basis of their intraoperative presentation. This provides further evidence that patients are capable of processing intraoperative auditory information.

Adult↗
PubMed1998

Neuropsychometric changes in patients after carotid endarterectomy.

BACKGROUND AND PURPOSE: One hundred twelve patients undergoing elective carotid endarterectomy for symptomatic and asymptomatic carotid artery stenosis were enrolled in a prospective study to evaluate the incidence of change in postoperative cerebral function. METHODS: Patients were evaluated preoperatively and postoperatively before hospital discharge and at follow-up 1 and 5 months later with a battery of neuropsychometric tests. The results were analyzed by both event-rate and group-rate analyses. For event-rate analysis, change was defined as either a decline or improvement in postoperative neuropsychometric performance by 25% or more compared with a preoperative baseline. RESULTS: Approximately 80% of patients showed decline in one or more test scores, and 60% had one or more improved test scores at the first follow-up examination. The percentage of declined test scores decreased and the percentage of improved test scores increased with subsequent follow-up examinations. Group-rate analysis was similar for group performance on individual tests. However, a decline in performance was seen most commonly on verbal memory tests, and improved performance was seen most commonly on executive and motor tests. CONCLUSIONS: Neuropsychometric evaluation of patients undergoing carotid endarterectomy for significant carotid artery stenosis demonstrates both declines and improvements in neuropsychometric performance. The test changes that showed decreased performance may be associated with ischemia from global hypoperfusion or embolic phenomena, and the improvement seen may be related to increased cerebral blood flow from removal of stenosis.

Aged↗
PubMed1997

Cerebral dysfunction after coronary artery bypass grafting done with mild or moderate hypothermia.

OBJECTIVE: Ninety-nine patients undergoing elective coronary artery bypass grafting were enrolled in a prospective, randomized study to evaluate the incidence of cerebral dysfunction after "mild" or "moderate" hypothermia during cardiopulmonary bypass. METHODS: Patients were evaluated before and after operation before hospital discharge and in some cases at follow-up at least 6 weeks later with a complete neurologic examination (85 patients) and a battery of standard neuropsychometric tests (86 patients). RESULTS: Postoperative changes detected by neurologic examination consisted of the appearance of new primitive reflexes in both groups. No statistically significant differences in incidence were found. The neuropsychometric performances of the two groups were statistically similar by either event-rate or group-rate analysis. CONCLUSIONS: There is no detectable difference in postoperative cerebral dysfunction in patients undergoing coronary artery bypass grafting who are supported by cardiopulmonary bypass with either mild or moderate hypothermia.

Aged↗
PubMed1997

Sympathetic response during cardiopulmonary bypass: mild versus moderate hypothermia.

OBJECTIVE: To determine the sympathetic response during cardiopulmonary bypass at mild (34 degrees C) and moderate (28 degrees C) hypothermia. DESIGN: A randomized study. SETTING: Tertiary university hospital. PATIENTS: Adults undergoing elective coronary artery bypass graft surgery. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Plasma norepinephrine, epinephrine, and neuropeptide Y concentrations were measured. Moderate, but not mild, hypothermic cardiopulmonary bypass evoked a significant sympathetic response with increases in plasma norepinephrine and neuropeptide Y concentrations. A significantly higher incidence of postoperative atrial fibrillation was also observed in the moderate hypothermic compared with the mild hypothermic group. CONCLUSIONS: Our results indicate that the degree of hypothermia significantly influences the sympathetic response during cardiopulmonary bypass. The higher incidence of postoperative atrial fibrillation in the moderate hypothermic group suggests that the enhanced sympathetic response might be one contributing factor in the development of atrial fibrillation.

Aged↗
PubMed1997

Effects of sire, dam traits, calf traits, and environment on dystocia and subsequent reproduction of two-year-old heifers.

A study was conducted over 3 yr to evaluate effects of sire birth weight EPD, calf birth weight and shape, and heifer pelvic area and weight, individually and in combination, on dystocia and subsequent rebreeding of 2-yr-old heifers. Heifers (n = 550), MARC II yearlings, were assigned for breeding to one of four Angus sires with birth weight EPD of -.95, -82, +2.9, and +2.7 kg. At calving, heifers were assisted as needed. A gauge attached to the cal puller recorded applied traction pressure. Analysis of traction pressure detected only slightly larger amounts of variation (2 to 3%) affecting dystocia than the standard five-point scoring system. Dam weight did not affect calving difficulty score (CDS), except dam birth weights were heavier (P < .05) for CDS 5 (Caesarean section) than CDS 1 (unassisted). Dams requiring Caesarean section had smaller pelvic areas (P < .05), with no other differences among CDS. The CDS increased as calf birth weight and cal external measurements increased. Low EPD sires produced calves with smaller (P < .05) birth weights and smaller calf head and food circumferences and caused less dystocia than high EPD sires. The CDS did not affect subsequent pregnancy rates but did affect conception date of the second calf. Calves delivered by Caesarean section were lighter (P < .05) at weaning than other calves but had similar slaughter weights. As mean winter temperature increased (6.1 degrees C) from yr 1 to 3, calf birth weight decreased (4.6 kg) and calving difficulty decreased 23%. Results indicate sire birth weight EPD, calf birth weight and shape, dam pelvic area, and climate affected CDS, and CDS affected subsequent conception date.

Aging↗
PubMed1996

Neurologic assessment and cardiac surgery.

Cerebral injury remains a significant complication of cardiac surgery. This complication is evaluated by clinical means that include a neurologic examination. In this report, the most important components of this type of evaluation are described. The neurologic complications of cardiac surgery can be determined by comparing structured preoperative and postoperative clinical evaluations. The neurologic examination must include a mental state examination, examination of cranial nerves, motor, sensory, and cerebellar systems, examination of gait and station, and deep tendon and primitive reflexes. The purpose of this report is to discuss the relevance of the neurologic examination in the assessment of cerebral injury after cardiac surgery, review the components of a structured neurologic examination, and explore the role of "quantitative" stroke scales as a research tool.

Brain Diseases↗