Biomedical subjects

D P Miller

Publications and source records attributed to D P Miller.

At least 19 recordsLinked to original sources

PubMed1997

Cardioversion guided by transesophageal echocardiography: the ACUTE Pilot Study. A randomized, controlled trial. Assessment of Cardioversion Using Transesophageal Echocardiography.

BACKGROUND: Electrical cardioversion in patients with atrial fibrillation is associated with an increased risk for embolic stroke. Screening for atrial thrombi with transesophageal echocardiography (TEE) before cardioversion should, in many patients, safely permit cardioversion to be done earlier than would be possible with prolonged conventional, anticoagulation therapy. OBJECTIVE: To compare the feasibility and safety of TEE-guided early cardioversion with those of conventional management of cardioversion in patients with atrial fibrillation. DESIGN: Randomized, multicenter clinical trial. SETTING: 10 hospitals in the United States, Europe, and Australia. PATIENTS: 126 patients who had atrial fibrillation lasting longer than 2 days and were having electrical cardioversion. INTERVENTION: Conventional therapy or early, TEE-guided cardioversion with short-term anticoagulation therapy. OUTCOME MEASURES: Feasibility outcome variables were frequency of cardioversion and times to cardioversion and sinus rhythm. Safety outcomes were ischemic stroke, transient ischemic attack, systemic embolization, bleeding, and detected episodes of clinical hemodynamic instability occurring as long as 4 weeks after cardioversion. RESULTS: 62 patients were randomly assigned to receive TEE-guided cardioversion; TEE was done in 56 (90%) of these patients. Atrial thrombi were detected in 7 patients (13%) and led to the postponement of cardioversion. Cardioversion was successful in 38 of 45 patients (84%) who had early cardioversion. No embolization occurred with this strategy. Of the 64 patients receiving conventional therapy, 37 (58%) had cardioversion, which was successful in 28 patients (76%). One patient had a peripheral embolic event. The time to cardioversion was shorter in the TEE group (0.6 weeks [95% CI, 0.3 to 0.9 weeks] compared with 4.8 weeks [CI, 3.8 to 5.7 weeks]; P < 0.01). The incidence of clinical hemodynamic instability and bleeding complications tended to be greater in the conventional therapy group. CONCLUSIONS: These results suggest that TEE-guided cardioversion with short-term anticoagulation therapy is feasible and safe. The use of TEE may allow cardioversion to be done earlier, may decrease the risk for embolism associated with cardioversion, and may be associated with less clinical instability than conventional therapy. A large, multicenter study to confirm these findings is currently under way.

Aged↗

PubMed1996

Inability of serum myocyte death markers to predict acute cardiac allograft rejection.

Acute cardiac rejection involves myocyte necrosis. Hence, markers of myocyte death may be useful in diagnosing rejection. Creatine kinase MB, MB isoforms, and troponins I and T were measured in 186 patients undergoing 365 endomyocardial biopsies. No differences were noted with rejection (rejectors vs. nonrejectors: CK=63.8 U/L and 86.6 U/L, P=0.0881; CK MB=2.04 ng/ml and 2.06 ng/ml, P=0.949; troponin T=0.134 ng/ml and 0.0881 ng/ml, P=0.374; troponin I=0.216 ng/ml and 0.707 ng/ml, P=0.357). The time course of troponins T and I levels in rejectors and nonrejectors do not differ with both groups having early elevations. Markers of myocyte death are inadequate predictors of acute rejection in cardiac allografts. The time course of troponins T and I suggests a possible role as prognostic indicators of outcome.

Acute Disease↗

PubMed1996

Determinants of the use of coronary angiography and revascularization after thrombolysis for acute myocardial infarction.

BACKGROUND: Clinical trials and practice guidelines have identified clinical criteria for the use of coronary angiography and revascularization procedures after thrombolysis for acute myocardial infarction. The effect of these criteria on clinical practice has not been extensively evaluated. METHODS: We used classification-and-regression-tree (CART) and logistic-regression models to study the patients in the first Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries trial, to identify the variables that best predicted the use of angiography and revascularization procedures after thrombolysis. RESULTS: Among the 21,772 U.S. patients in the trial, 71 percent underwent coronary angiography before discharge from the hospital. Of these, 58 percent underwent revascularization (73 percent receiving angioplasty). The CART model for the use of angiography showed that age was the variable most predictive of angiography; only 53 percent of patients at least 73 years of age underwent angiography, as compared with 76 percent of those under 73. Among the older patients, age was again the most predictive factor; among the younger patients, the availability of angioplasty was a more important predictor (67 percent of patients in hospitals without angioplasty facilities underwent angiography, as compared with 83 percent in hospitals with such facilities). The next most important variable was recurrent ischemia, which was more predictive at hospitals without angioplasty facilities than at those with them. Both statistical models identified coronary anatomy as the most important predictor of the use and type of revascularization. CONCLUSIONS: More patients treated with thrombolysis underwent angiography and revascularization before discharge than might be expected. Younger age and the availability of the procedures appeared to be the major determinants of the use of coronary angiography, whereas coronary anatomy largely determined the use and type of revascularization. This process appeared to select low-risk patients for intervention rather than those at higher risk, who would be the most likely to benefit.

Age Factors↗

PubMed1996

Natural history of isolated bundle branch block.

The purpose of this study was to determine the long-term outcome of patients with bundle branch block (BBB) who have no clinical evidence of cardiovascular disease. Among 110,000 participants in a screening program, 310 subjects with BBB without apparent of suspected heart disease were identified. Their outcome after a mean follow-up of 9.5 years was compared with that of 310 similarly screened age- and sex-matched controls. Among the screened population, isolated right BBB was more prevalent than isolated left BBB (0.18% vs 0.1%, respectively; p<0.001), and the prevalence of each abnormality increased with age (p<0.001). Total actuarial survival was no different for those with left BBB or right BBB and their respective controls. Cardiac mortality, however, was increased in the left BBB group when compared with their controls (p=0.01, log rank test). Left BBB, but not right BBB, was associated with an increased prevalence of cardiovascular disease at the follow-up (21% vs 11%; p=0.04). In the absence of clinically overt cardiac disease, the presence of left BBB or right BB is not associated with increased overall mortality. Isolated left BBB is associated with an increased risk of developing overt cardiovascular disease and increased cardiac mortality.

Adult↗

PubMed1996

Outmigration for coronary bypass surgery in an era of public dissemination of clinical outcomes.

BACKGROUND: Since 1989, New York State has disseminated comparative information on outcomes of coronary bypass surgery to the public. It has been suggested that this program played a significant role in the 41% decrease in the risk-adjusted mortality rate between 1989 and 1992. We hypothesized that some high-risk patients had migrated out of state for surgery. METHODS AND RESULTS: We reviewed 9442 isolated coronary bypass operations performed from 1989 through 1993 to assess referral patterns of case-mix and outcome. Expected and risk-adjusted mortality rates were computed using logistic regression models derived from the Cleveland Clinic and New York State databases. A mortality comparison was performed using the 1980 to 1988 time period as a historical control. Patients from New York (n=482) had a higher frequency of prior open heart surgery (44.0%) than patients from Ohio (n=6046) (21.5%, P<.001), other states (n=1923) (37.4%, P=.008), and other countries (n=991) (17.3%, P<.001). They were also more likely to be in NYHA functional class III or IV (47.6% versus Ohio 42.7%, P=.037; other states, 41.2%, P=.011; other countries, 34.1%, P=.001). The expected mortality rate was thus higher than among other referral cohorts. The observed 5.2% mortality rate among these patients was significantly greater than the 2.9%, 3.1%, and 1.4% mortality rates observed for patients from Ohio (P=.004), other states (P=.028), and other countries (P<.001). These differences in outcome were not apparent between 1980 and 1988 among referrals from within the United States. CONCLUSIONS: Public dissemination of outcome data may have been associated with increased referral of high-risk patients from New York to an out-of-state regional medical center.

Coronary Artery Bypass↗

PubMed1996

Neural substrates of discriminative avoidance learning and classical eyeblink conditioning in rabbits: a double dissociation.

In a previous study, lesions of the deep cerebellar nuclei blocked classical eyeblink conditioning, but did not impair discriminative avoidance learning in rabbits. Here, was also found previously, lesions of the anterior and medial dorsal thalamic nuclei severely impaired discriminative avoidance learning. However, these lesions had no impact on discriminative eyeblink conditioning or reversal learning. These results complete the demonstration of a double dissociation, indicating distinct neural substrates for the acquisition of these learned behaviors. It is proposed that the two learning circuits identified by these studies mediate, respectively, acquisition of specific adaptive reflexes and whole-body, voluntary goal-directed movements.

Animals↗

PubMed1995

Hyperhomocysteinemia and low pyridoxal phosphate. Common and independent reversible risk factors for coronary artery disease.

BACKGROUND: High plasma homocysteine is associated with premature coronary artery disease in men, but the threshold concentration defining this risk and its importance in women and the elderly are unknown. Furthermore, although low B vitamin status increases homocysteine, the link between these vitamins and coronary disease is unclear. METHODS AND RESULTS: We compared 304 patients with coronary disease with 231 control subjects. Risk factors and concentrations of plasma homocysteine, folate, vitamin B12, and pyridoxal 5'-phosphate were documented. A homocysteine concentration of 14 mumol/L conferred an odds ratio of coronary disease of 4.8 (P < .001), and 5-mumol/L increments across the range of homocysteine conferred an odds ratio of 2.4 (P < .001). Odds ratios of 3.5 in women and of 2.9 in those 65 years or older were seen (P < .05). Homocysteine correlated negatively with all vitamins. Low pyridoxal 5'-phosphate (< 20 nmol/L) was seen in 10% of patients but in only 2% of control subjects (P < .01), yielding an odds ratio of coronary disease adjusted for all risk factors, including high homocysteine, of 4.3 (P < .05). CONCLUSIONS: Within the range currently considered to be normal, the risk for coronary disease rises with increasing plasma homocysteine regardless of age and sex, with no threshold effect. In addition to a link with homocysteine, low pyridoxal-5'-phosphate confers an independent risk for coronary artery disease.

Age Factors↗

PubMed1995

Regional variation across the United States in the management of acute myocardial infarction. GUSTO-1 Investigators. Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries.

BACKGROUND: Differences in the management of acute myocardial infarction have been reported among countries, but few studies have investigated this issue in regions of the United States. METHODS: We compared the management of acute myocardial infarction among census regions across the United States, using data from the first Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries trial (GUSTO-1) comprising 21,772 patients, and from the American Hospital Association. RESULTS: We found substantial regional variation in the management of acute myocardial infarction in the United States. Beta-blockers (prescribed for a range of 55 to 81 percent of patients in the various regions), nitrates (prescribed for 61 to 77 percent), and angiotensin-converting-enzyme inhibitors (prescribed for 18 to 23 percent) were used most often in New England, whereas calcium-channel blockers (31 to 42 percent) and lidocaine (14 to 43 percent) were used least often there. Similarly, the proportion of patients undergoing various cardiac procedures differed among regions (range for angiography, 52 to 81 percent of patients; angioplasty, 22 to 35 percent; and coronary-artery bypass surgery, 9 to 17 percent) and was lowest in New England. The regional use of cardiac procedures was closely related to their availability, except in New England. After the analysis was adjusted for clinical and hospital variables, patients in New England were found to be less likely to undergo angiography than patients in the other regions (odds ratio, 0.37; 95 percent confidence interval, 0.32 to 0.42). There was no apparent relation between the use of cardiac procedures and rates of recurrent infarction or death at 30 days or 1 year. CONCLUSIONS: There is substantial regional variation in the use of cardiac medications and procedures to manage acute myocardial infarction in the United States. The use and availability of cardiac procedures are closely related. The management of acute myocardial infarction in New England is atypical in that the relatively limited availability of cardiac procedures does not account for their relatively low use in that region.

Angioplasty↗

PubMed1995

In-hospital cost of percutaneous coronary revascularization. Critical determinants and implications.

BACKGROUND: Hospital charges associated with percutaneous transluminal coronary revascularization (PTCR) in the United States exceeded $6 billion in 1994 and are likely to be constrained in some manner in the near future. Despite this high cost to the public, little is known about the major determinants and sources of variability of PTCR. METHODS AND RESULTS: From a consecutive series of 1258 procedures with attempted PTCR at a single tertiary referral center, we analyzed 65 clinical, angiographic, physician, and outcome variables as potential correlates of total (hospital and physician) cost. Direct and indirect costs, both hospital and physician, were determined on the basis of resource utilization using "top-down" methodology and were available for 1237 procedures (1086 patients) (98.3%). Mean (+/- SD) patient age was 62 +/- 11 years, 76% were male, 3% had acute myocardial infarction, 71% had unstable angina, 58% had multivessel disease, left ventricular ejection fraction was 54 +/- 12%, 26% had use of at least one nonballoon revascularization device, and median length of stay was 4.4 days. Procedural success was obtained in 89%, and major complications (death, bypass surgery, or Q-wave myocardial infarction) occurred in 3.8%. The median cost was $9176, but it was asymmetrically distributed, and the interquartile and total ranges were wide ($7333 to $13,845 and $3422 to $193,474, respectively). Analyses of independent correlates of cost and loge(cost) were performed using multivariate linear regression in training and test populations. Modeling found 15 independent preprocedural correlates of loge(cost) (R2 = .37) and 23 overall correlates (R2 = .65), excluding length of stay per se. Additional of length of stay to the model increased the explanatory power of the model to R2 = .82. Preprocedural variables most predictive of loge(cost) included presentation with acute myocardial infarction, decision delay (> 48 hours between admission and diagnostic angiography and/or > 24 hours between angiography and intervention), weekend delay, use of intra-aortic balloon counterpulsation, intention to stent, creatinine > or = 2.0 mg%, and lesion complexity (modified American College of Cardiology/American Heart Association score) (all P < .001). In the model that included postprocedural variables as well, length of stay, noncardiac death, urgent bypass surgery, use of the Rotablator, Q-wave myocardial infarction, rise in creatinine > or = 1.0%, and blood product transfusion were all strong independent correlates of loge(cost) (P < .001). CONCLUSIONS: The range of total hospital costs associated with percutaneous intervention is extraordinarily wide. Baseline patient characteristics account for nearly half of the explained variance, but procedural complications and system delays account for much of the remainder. Quantification of the determinants of cost may promote more economically efficient care in the future.

Aged↗

PubMed1995

Surgical management of hypertrophic obstructive cardiomyopathy. Early and late results.

From 1975 through 1993, 178 patients underwent surgical management of hypertrophic obstructive cardiomyopathy. Operations included isolated septal myectomy (n = 95), septal myectomy and coronary artery bypass grafting (n = 41), septal myectomy plus a valve procedure (n = 25), septal myectomy, valve procedure, and coronary artery bypass grafting (n = 14), and mitral valve replacement without septal myectomy (n = 3). Recent myectomy results were monitored with transesophageal echocardiography. After initial myectomy, 32 patients (20%) underwent a second pump run for more extensive myectomy only (n = 22), mitral valve replacement only (n = 5), or both (n = 2). In-hospital mortality was 6% (n = 11) and 4% (n = 6) for patients undergoing septal myectomy or septal myectomy plus coronary artery bypass grafting, respectively. Heart block occurred in 17 patients (10%). Left ventricular outflow tract systolic gradients decreased from a mean of 93 mm Hg to 21 mm Hg after myectomy. Late survival was 86% and 70% at 5 and 10 postoperative years, respectively, and 93% and 79% for patients undergoing septal myectomy alone or septal myectomy plus coronary artery bypass grafting, respectively. Only 3 of 131 in-hospital survivors of septal myectomy or septal myectomy plus coronary artery bypass grafting died late cardiac deaths, for a yearly mortality of 0.6%. However, the 5-year late survival of patients undergoing valve operation plus septal myectomy was 51%, and multivariate testing confirmed the adverse influence on late survival (p = 0.008), as well as adverse influences of increasing age (p = 0.016) and return to cardiopulmonary bypass for mitral valve replacement (p = 0.038). At follow-up 136 patients (94%) had New York Heart Association class I or II symptoms. For patients with hypertrophic obstructive cardiomyopathy, septal myectomy alone or in combination with coronary artery bypass grafting produces effective symptom relief, excellent long-term survival, and a low risk of late cardiac death.

Aged↗

PubMed1995

The Carpentier-Edwards pericardial aortic valve. Ten-year results.

To evaluate the function of the Carpentier-Edwards pericardial valve in the aortic position, we analyzed the results of 310 aortic valve replacements performed between 1982 and 1985. Mean age was 64.2 +/- 10.8 years (range 22 to 95 years); 190 patients (61.3%) were male patients. There were 18 hospital deaths (5.8%), and none were valve related. Follow-up of the 292 survivors was 100% complete at a mean of 7.8 +/- 2.9 years; 2290 patient-years of follow-up were available for analysis. There were 133 late deaths (45.5%). Actuarial survivals at 5 and 10 years were 82.5% and 45.9%, respectively. The 10-year actuarial freedom from events was 88.7% +/- 2.1% for thromboembolism, 90.9% +/- 1.8% for hemorrhage, 94.3% +/- 1.6% for endocarditis, and 91.2% +/- 2.6% for structural deterioration. The 153 hospital survivors 65 years of age or older had an extremely low incidence of structural valve deterioration, with only four explants and 95.5% actuarial freedom from explantation at 10 years, and a linearized rate of 0.3 +/- 0.2 per patient-year compared with 88.6% and 0.7 +/- 0.2 for patients younger than 65 years of age. Twelve valves were explanted for structural deterioration. Of these, 11 (93%) had leaflet calcification causing stenosis and one had a wear-related leaflet tear. The Carpentier-Edwards pericardial valve has a low incidence of valve-related complications. The freedom from structural valve deterioration is low at 10 years, particularly in patients 65 years of age and older.

Actuarial Analysis↗

PubMed1995

Management of small unilateral renal cell carcinomas: radical versus nephron-sparing surgery.

OBJECTIVES: There is controversy concerning the management of small unilateral renal cell carcinomas. The present study was undertaken to evaluate the relative efficacy of radical nephrectomy versus nephron-sparing surgery in such patients. METHODS: Patients with a single, small (less than 4 cm), localized, unilateral, sporadic renal cell carcinoma (RCC) were identified from an institutional registry. From 1975 to 1992, 88 patients fulfilling these criteria were treated with either radical nephrectomy (n = 42) or nephron-sparing surgery (n = 46). The mean postoperative follow-up interval is 48 +/- 29 months. RESULTS: The radical and nephron-sparing surgical groups were well matched for patient age, sex, renal function, diabetes, hypertension, tumor size, tumor location, and tumor stage. All patients in both groups had low pathologic stage RCC. There was no difference between the two groups in terms of the mean hospital stay, the requirement for blood transfusions, or the occurrence of surgical complications. There was no difference in the mean preoperative and postoperative serum creatinine levels for patients in the nephron-sparing surgery group. However, the mean postoperative serum creatinine levels were significantly higher than the mean preoperative levels for patients in the radical nephrectomy group (P < 0.001). A single patient in each group developed recurrent RCC postoperatively. The cancer-specific 5-year survival rate for patients in the radical and nephron-sparing surgical groups is 97% and 100%, respectively. CONCLUSIONS: Radical nephrectomy and nephron-sparing surgery each provide safe and effective curative treatment for patients with a single, small, unilateral localized RCC. The long-term renal functional advantage of nephron-sparing surgery in this setting is not established.

Aged↗

PubMed1995

Genetic modification of an entomopoxvirus: deletion of the spheroidin gene does not affect virus replication in vitro.

In the late stages of an entomopoxvirus infection, virions become embedded within a crystalline occlusion body or spheroid. Spheroids are composed primarily of a single polypeptide, spheroidin. We describe the construction of a genetically modified Amsacta moorei entomopoxvirus (AmEPV) in which the spheroidin gene coding sequences are deleted and replaced with those of a heterologous reporter gene encoding chloramphenicol acetyltransferase (CAT). A transfer vector, pAmCP1, was prepared containing a unique BamHI site in lieu of the spheroidin gene coding region, together with 1 kbp of upstream and downstream DNA sequence that flanks the spheroidin gene. The flanking sequences provide the transcriptional control signals and also guide homologous recombination so that the spheroidin gene coding region can be replaced with that of the foreign gene. The transfer vector was designed so that the translational start codon of the introduced foreign gene would be utilized. A recombinant virus, AmEPV.CAT, was produced by transfecting AmEPV-infected cells with the transfer vector encoding the CAT gene. The recombinant virus was isolated from wild-type virus by identifying plaques with a spheroidin-negative phenotype. Light microscopy and SDS-PAGE analysis demonstrated that no spheroids or spheroidin protein were produced in the recombinant virus-infected cells. The recombinant virus was able to replicate to high titres (10(7) p.f.u./ml) in insect cells indicating that the spheroidin gene is non-essential for AmEPV replication in vitro. Moderate levels of CAT were synthesized in recombinant virus-infected cells and temporal analyses indicated that CAT synthesis followed the pattern of spheroidin production suggesting that the spheroidin gene promoter was functioning under normal regulatory control in the genetically modified virus.

Base Sequence↗

PubMed1995

Treatment of renal cell carcinoma in von Hippel-Lindau disease: a multicenter study.

A total of 65 patients with von Hippel-Lindau disease underwent surgery for renal cell carcinoma (54 bilaterally and 11 unilaterally) at 8 medical centers. Only 1 patient presented with metastatic disease. Radical nephrectomy and nephron sparing surgery were performed in 16 and 49 patients, respectively. Mean posttreatment followup was 68 months. The 5 and 10-year cancer-specific survival rates for all patients were 95% and 77%, respectively. The corresponding rates for patients treated with nephron sparing surgery were 100% and 81%, respectively. Of the latter patients 25 (51%) had postoperative local tumor recurrence but only 2 had concomitant metastatic disease. Survival free of local recurrence was 71% at 5 years but only 15% at 10 years. End stage renal failure occurred in 15 patients (23%): 6 underwent renal transplantation (5 are alive with satisfactory renal function and no evidence of malignancy) and 9 were treated with chronic dialysis (6 are free of tumor). Our results indicate that nephron sparing surgery can provide effective initial treatment for patients with renal cell carcinoma and von Hippel-Lindau disease. These patients must be followed closely, since most will eventually have locally recurrent renal cell carcinoma. When removal of all renal tissue is necessary to achieve control of malignancy, renal transplantation can provide satisfactory replacement therapy for end stage renal disease.

Adolescent↗

PubMed1994

Neuronal activity in rabbit neostriatum during classical eyelid conditioning.

Extracellular multiple- and single-unit recordings were made from the neostriatum of rabbits during classical eyelid conditioning. Neostriatal neurons processed information regarding the conditioned auditory stimulus (CS) and conditioned eyelid response (CR) as well as the unconditioned stimulus/response (US/UR). These data are consistent with previous reports that neostriatal neurons respond to movement and movement-related sensory stimuli. In most cases, neostriatal neurons increased activity to the US during the early phase of training, but to the CR as training progressed. A close temporal correlation was found between neuronal activity and CR onset with unit discharges typically preceding CR onset by 10-50 ms. The activity of some multiple and single units was monitored after injection of haloperidol, a neuroleptic and dopamine antagonist known to disrupt neostriatal function. Interestingly, haloperidol caused a greater disruption of CRs at low-intensity than at high-intensity CSs, but conditioning-related neuronal activity was disrupted equally at both intensities. These data are discussed in terms of a possible role for the neostriatum in eyelid conditioning.

Animals↗

PubMed1994

Multifocal renal cell tumors: a retrospective analysis of 56 patients treated with radical nephrectomy.

In this retrospective analysis of 56 patients with multifocal renal cell tumors the effect of secondary tumors on the prognosis was examined and the incidence of tumors in the contralateral kidney was evaluated. All of the primary tumors were renal cell carcinomas, the majority of which had a local tumor stage of pT2 (31 cases, 55.3%) and a cytological grading of 1 (23 cases, 41%). The mean size of the secondary tumors was 1.0 cm. An additional tumor was diagnosed in 23 patients (41%), 2 to 5 secondary tumors in 23 (41%) and more than 5 additional tumors in 10 (18%). The overall 5-year survival rates were 69.4%, 72.2% and 40%, respectively (p = 0.313). Histopathological differentiation of the additional lesions revealed 23.2% renal cell carcinomas, 71.4% adenomas and 5.3% renal tumors of "doubtful dignity," with overall 5-year survival rates of 67.2% for adenomas, and 60.6% for carcinomas and renal tumors of "doubtful dignity" (p = 0.546). After a mean followup of 60 months 33 patients (58.9%) were alive without evidence of disease, 1 (1.7%) was alive with tumor progression, 8 (14.2%) died of the disease and 14 (25%) died of other causes; only 1 patient presented with a tumor in the contralateral kidney (incidence 1.7%). Thus, the overall 5-year survival rate for the entire group was 66.0% and the histopathological parameters of the additional tumors had no effect on the prognosis of the patients.

Adenoma↗

PubMed1993

Miniature crystal models of cellulose polymorphs and other carbohydrates.

Miniature crystal models of cellulose and other carbohydrates were evaluated with the molecular mechanics program MM3. The models consisted of groups of 24 to 32 monosaccharide residues, with the models of mono- and disaccharides based on well-established, single-crystal work. Structures of the cellulose forms and cellotetraose were based on published work using fibre diffraction methods. A structure for the single-chain I alpha cellulose unit cell was also tested. A dielectric constant of about 4 was best for this type of work. Calculated intra- and intermolecular energy for glucose agreed with literature values for the heat of combustion. Cellulose II had the lowest calculated energy for a cellulose form, followed by I alpha, cellulose III(I), ramie I, IV(II) and IV(I). Optimization of cellulose IV caused larger mean atomic movements from the original crystallographic positions than the other cellulose forms, and cellotetraose had larger movements than any of the other structures. Lattice energies for the cellulose forms were about 20 kcal/mol of glucose residues, with a dominant van der Waals component.

Carbohydrates↗

PubMed1993

Using signaled barpressing tasks to study the neural substrates of appetitive and aversive learning in rats: behavioral manipulations and cerebellar lesions.

The development of standard within-subject conditioning tasks for studying similarities and differences in the neural substrates of appetitive and aversive learning is described. Rats learned to press a bar during a brief tone presentation to receive a food pellet reward (the appetitive task). Using the same tone signal, conditioning chamber, and trial timing parameters, the same rats were then trained to press the bar during the tone presentation to avoid a mild footshock (the aversive task). As an initial study of the neural substrates of these forms of learning, the involvement of the cerebellum was assessed. Bilateral lesions of the deep cerebellar nuclei prevented the learning of the aversive task but had no effect on the learning of the appetitive task.

Animals↗