Search PubMed⌕ Search

Biomedical subjects

C S Roberts

Publications and source records attributed to C S Roberts.

At least 37 records · Page 2Linked to original sources
PubMed1999

Should distal interlocking of tibial nails be performed from a medial or a lateral direction? anatomical and biomechanical considerations.

OBJECTIVE: To compare the relative risks of neurovascular injury from perforation during distal interlocking and the biomechanical stability of two approaches to distal interlocking of tibial nails. DESIGN: In vitro anatomical and biomechanical study. SETTING: All mechanical testing was performed in a servohydraulic test frame with a customized motion transducer. INTERVENTION: Tibial nails were interlocked distally with a medial-to-lateral (ML) or a lateral-to-medial (LM) approach. MAIN OUTCOME MEASURE: The distances from the nearest end of each distal locking screw to four neurovascular structures were measured manually with calipers, and two-dimensional motion under simulated stance load across the fracture site was recorded. RESULTS: There were greater distances from the posterior tibial neurovascular bundle and the superficial peroneal nerve with distal targeting from the LM direction compared with targeting from the ML direction. Biomechanically, the ML nail configuration demonstrated slightly greater resistance to bending than the LM configuration. CONCLUSIONS: Distal tibial interlocking from the LM direction appears to be safer than interlocking from the ML direction with regard to relative distances from the neurovascular structures. This small anatomical advantage must be considered in light of slightly greater resistance to bending of the ML interlocking configuration compared with the LM interlocking configuration.

Biomechanical Phenomena↗
PubMed1999

Pathologic fracture of the humerus due to metastatic cholangiocarcinoma.

Cholangiocarcinoma is a rare tumor of the bile duct system known to frequently metastasize to the axial skeleton, lungs, adrenal glands, brain, and lymphatic system. Spread to the long bones has not previously been reported in the literature partly because of the short life expectancies of patients with this disease. We discuss a case of a pathologic humerus fracture due to metastatic cholangiocarcinoma.

Bile Duct Neoplasms↗
PubMed1999

When the care giver needs care.

Case studies are used to illustrate family dysfunction that can occur when the wife and/or mother who has assumed the role of primary care giver is diagnosed and treated for cancer. These women were treated by the liaison psychiatrist and social workers at a large cancer center. The cases are discussed from a framework of family systems theory. Treatment implications for social workers in health care are also presented.

Adult↗
PubMed1998

Psychosocial issues of adolescents with cancer.

Although researchers agree that cancer during adolescence does not lead to serious psychopathology, the adolescent patient is confronted with a number of biopsychosocial problems. This article reviews the literature on nine psychosocial issues: (1) Health concerns, (2) Family relationships, (3) Sexual and reproductive issues, (4) Peer relationships, (5) Body image, (6) School disruption, (7) Interaction with treatment team, (8) Future goals and career development, and (9) Positive life changes. Practice implications and support group interventions for this population are presented.

Achievement↗
PubMed1998

Spinal ligament loading during axial distraction: a biomechanical model.

The objective of this study was to develop a method of measuring spinal ligament forces during axial distraction to understand the load-bearing contributions of the individual ligamentous structures in the lumbar spine. A sequential ligament-cutting technique and the arthroscopically implantable force probe (AIFP, MicroStrain, Burlington, VT) were used to determine loading of the anterior longitudinal ligament (ALL), the posterior longitudinal ligament (PLL), and the remaining posterolateral complex (PLC) in an in vitro corpectomy model. During axial spinal distraction, the relative percentages of the total axial load in the individual structures were as follows: ALL, 37.5%; PLL, 17.2%; PLC, 45.3%.

Aged↗
PubMed1998

Sonography for the office screening of suspected rotator cuff tears: early experience of the orthopedic surgeon.

This study examined the feasibility of orthopedic surgeons performing sonography of the shoulder at the initial office evaluation of the rotator cuff and assessed the sensitivity, specificity, and predictive value of sonography for the detection of tears in the rotator cuff. Initial results in 24 patients suggest that sonography by the orthopedic surgeon is feasible and that it detects tears in the rotator cuff with sufficient accuracy for clinical decision making.

Adult↗
PubMed1997

Comprehensive strategy for the evaluation and triage of the chest pain patient.

STUDY OBJECTIVE: To evaluate the safety and efficacy of a systematic evaluation and triage strategy including immediate resting myocardial perfusion imaging in patients presenting to the emergency department with chest pain of possible ischemic origin. METHODS: We conducted an observational study of 1,187 consecutive patients seen in the ED of an urban tertiary care hospital with the chief complaint of chest pain. Within 60 minutes of presentation, each patient was assigned to one of five levels on the basis of his or her risk of myocardial infarction (MI) or unstable angina (UA): level 1, MI; level 2, MI/UA; level 3, probable UA; level 4, possible UA; and level 5, noncardiac chest pain. In the lower risk levels (3 and 4), immediate resting myocardial perfusion imaging was used as a risk-stratification tool alone (level 4) or in combination with serial markers (level 3). RESULTS: Acute MI, early revascularization indicative of acute coronary syndrome, or both were consistent with risk designations: level 1: 96% MI, 56% revascularization; level 2: 13% MI, 29% revascularization; level 3: 3% MI, 17% revascularization; level 4: .7% MI; 2.5% revascularization. Sensitivity of immediate resting myocardial perfusion imaging for MI was 100% (95% confidence interval [CI], 64% to 100%) and specificity 78% (74% to 82%). In patients with abnormal imaging findings, risk for MI (7% versus 0%, P < .001; relative risk [RR], 50; 95% CI, 2.8 to 889) and for MI or revascularization (32% vs 2%, P < .001; RR, 15.5; 95% CI, 6.4 to 36) were significantly higher than in patients with normal imaging findings. During 1-year follow-up, patients with normal imaging findings (n = 338) had an event rate of 3% (revascularization) with no MI or death (combined events: negative predictive value, 97%; 95% CI, 95% to 98%). Patients with abnormal imaging findings (n = 100) had a 42% event rate (combined events: RR, 14.2; 95% CI, 6.5 to 30; P < .001), with 11% experiencing MI and 8% cardiac death. CONCLUSION: This strategy is a safe, effective method for rapid triage of chest pain patients. Rapid perfusion imaging plays a key role in the risk stratification of low-risk patients, allowing discrimination of unsuspected high risk patients who require prompt admission and possible intervention from those who are truly at low risk.

Adult↗
PubMed1997

Use of the combination of myoglobin and CK-MB mass for the rapid diagnosis of acute myocardial infarction.

Early identification of patients presenting with myocardial infarction (MI) is necessary for rapid initiation of treatment. Currently, MI has been diagnosed using the combination of the history, electrocardiogram (ECG), and biochemical markers of myocardial necrosis. Unfortunately, all lack sufficient sensitivity and specificity to confidently identify most patients with MI in a timely enough fashion to influence early intervention. Development of newer immunochemical assays for CK-MB mass and myoglobin have allowed for earlier, more rapid diagnosis; however, each has important limitations. The diagnostic sensitivity of CK-MB mass, myoglobin, and the combination of both were analyzed at the time of presentation (0 hours) and again 4 hours later in 101 patients admitted from the emergency department (ED) with possible MI. Twenty patients were subsequently diagnosed as having MI. The sensitivity of the initial ECG was 60%, compared with the sensitivities of the initial myoglobin and CK-MB mass of 70% and 30%, respectively. By 4 hours the sensitivity of myoglobin had increased to 85% and CK-MB mass to 90%. The combination of the initial myoglobin and CK-MB mass had a sensitivity of 85%. Combining these two markers, using both the initial and 4-hour samples, raised the sensitivity to 100%, with a specificity of 100% and negative predictive value of 100%. When patients with diagnostic ECGs were excluded, the sensitivity of the combination at 0 hours was 80% with a specificity of 84%, while the use of the 0- and 4-hour markers had a sensitivity and specificity of 100% and 100%, respectively. We conclude that the combination of CK-MB mass and myoglobin can rapidly diagnose or exclude MI in as short as 4 hours after ED presentation, and accuracy is not different in patients without diagnostic ECGs. Application of this strategy could potentially lead to more rapid intervention in patients with MI, while also allowing early identification of lower risk patients.

Biomarkers↗
PubMed1997

A support group intervention to facilitate young adults' adjustment to cancer.

Results of a previous survey of 46 young adults with cancer led to the development of a professionally led support group to address their unique concerns. The intervention combined group therapy techniques with Psychoeducational strategies in six weekly sessions on the topics of anxiety about health and physical well-being, worry about fertility and raising children, problems in relationships, financial concerns, and body image. Pretest and posttests demonstrated significant improvement in the 14 participants' scores on a measure of psychological well-being but no changes in coping mechanisms or overall quality of life. Practice recommendations include expanding the group to eight sessions and providing less structure. Arguments in favor of time-limited group interventions for cancer patients are presented.

Adaptation, Psychological↗
PubMed1997

Biomechanics of in situ rod contouring of short-segment pedicle screw instrumentation in the thoracolumbar spine.

In situ rod contouring is proposed as a means of three-dimensionally controlling the three columns of the spine. Our goal was to determine the biomechanical effectiveness of the technique for both clinical application and future research. Six cadaver specimens were tested with pedicle screw instrumentation from T12 to L2 in an L1 corpectomy model with all longitudinal ligaments retained across the defect. Contouring moment, anterior longitudinal ligament (ALL) forces, and distraction and lordosis across L1 were monitored. Rods were contoured to 26 degrees, and axial distraction averaged 6.9 mm. Bone/screw-interface failure began during contouring in every case < 10 degrees with no resulting increase in lordosis across L1. High tensile forces generated in the ALL resisted the moment applied by the rod benders and instead caused failure of the weaker bone/screw interface.

Aged↗
PubMed1996

Breast cancer patients' personality style, age, and treatment decision making.

BACKGROUND: Previous studies have shown that whereas nearly all cancer patients want information, far fewer wish to make treatment decisions. Although breast cancer patients who were given a choice of lumpectomy versus mastectomy and were encouraged to make the decision were believed to do better psychologically, a 1994 study refuted this. Some authors suggest that patient personality style is an important consideration in decisional preference. METHODS: Newly diagnosed breast cancer patients (n = 76) were surveyed within 6 months of surgery. They answered seven questions about patient and physician roles in the decision-making process. Additionally, they completed the Miller Behavioral Style Scale (MBSS), which categorizes "monitors," or information seekers, and "blunters," or information avoiders. Chi-square analyses were used to explore the relationship of personality style and age to treatment decision-making preferences. RESULTS: Although 80% of women wanted a role in decision making, 74% wanted their surgeons to make a recommendation and when given, 94% followed the recommended treatment plan. Monitors and blunters were equally likely to want physician recommendations. Younger women, particularly those under age 40, were more likely to want a physician's recommendation. Of those women who had specific fears about their cancer (76%), only half of them revealed such fears to their doctors. CONCLUSIONS: The notion that health care consumers, particularly younger ones, desire an independent choice of treatment was contradicted in this study. Physicians are encouraged to provide information and to probe regarding the fears of breast cancer patients in order to reduce anxiety while recognizing that treatment recommendations are desired by most women.

Adult↗
PubMed1996

Canine double-lung transplantation with cadaveric donors.

If lungs could be retrieved from cadavers after circulatory arrest, the critical shortage of donors for lung transplantation might be alleviated. To assess gas exchange after transplantation of lungs from cadaveric donors, we performed double-lung transplantation through sequential thoracotomies in 12 dogs. Donors were sacrificed by intravenous pentobarbital injection and then ventilated with 100% oxygen. Lungs were harvested 2 hours (n = 6) or 4 hours (n = 6) after death and flushed with 2 L modified Euro-Collins solution. Recipients underwent sequential right and left lung transplantation; they were then monitored while under anesthesia for 8 hours, with adjustments of the fraction of inspired oxygen. Nine of 12 recipients survived the 8-hour study period. Four of six dogs with cadaveric lungs retrieved 2 hours after death survived; deaths were from pulmonary embolism at 6 hours and pulmonary edema at 2 hours. Five of six dogs with cadaveric lungs retrieved 4 hours after death survived; one died of hypoxia during implantation of the left lung, while dependent on the right lung graft. Postoperative hemodynamic and gas exchange parameters were similar in both groups. Alveolar-arterial oxygen gradient rose significantly compared with baseline 1 hour after transplantation in both groups (462 +/- 60 vs 38 +/- 31 mmHg for 2-hour group, p < 0.0001, and 484 +/- 63 vs 38 +/- 14 mmHg for 4-hour group, p < 0.0002). By 8 hours after operation, the gradients had significantly decreased in both groups (105 +/- 37 mm Hg for 2-hour group and 146 +/- 53 mm Hg for 4-hour group) and were similar to baseline values. Extravascular lung water also rose significantly 1 hour after transplantation (15.7 +/- 2.8 vs 7.9 +/- 0.5 ml/kg for 2-hour group, p < 0.02, and 16.9 +/- 1.2 vs 6.6 +/- 0.4 ml/kg for 4-hour group, p < 0.0001) and decreased gradually during the 8-hour study period. Donor lungs retrieved at 2 and 4 hours postmortem afford similar recipient outcomes. Improvement in alveolar-arterial oxygen gradient and reduction in extravascular lung water during the study period imply that the ischemia-reperfusion injury induced by this model is reversible. If this approach could be safely introduced to clinical practice, substantially more transplant procedures could be performed.

Anesthesia, General↗
PubMed1996

Lung retrieval from cadaver donors with nonbeating hearts: optimal preservation solution.

BACKGROUND: We have previously studied the time course of pulmonary cell viability, ultrastructural damage, and adenine nucleotide metabolites after circulatory arrest in a rat model to investigate the feasibility of lung retrieval for transplantation from cadavers. This study was designed to investigate the effect of hypothermic flush and subsequent 4-hour storage with either modified Euro-Collins or University of Wisconsin solution on lungs retrieved 4 hours after death. METHODS: Ninety-six Sprague-Dawley rats were sacrificed by intraperitoneal injection of pentobarbital. Control lungs were flushed immediately after sacrifice and stored for 4 hours. Rats in the experimental groups were sacrificed, and then their lungs were either ventilated with 100% oxygen or not ventilated for 4 hours before flushing with either Euro-Collins or University of Wisconsin solution followed by 4-hour hypothermic storage. At the end of the storage period, all right lungs were maintained at -70 degrees C and used to determine wet-to-dry weight ratios and adenine nucleotide levels with high-pressure liquid chromatography. Left lungs were assessed for viability with trypan blue dye exclusion. The effect on viability of flushing with Carolina rinse solution after storage was also assessed. RESULTS: The percentage of viable cells in the control group after 4-hour hypothermic storage was 74% +/- 2% in Euro-Collins solution-flushed lungs and 78% +/- 2% in University of Wisconsin solution-flushed lungs. This result was virtually identical to that of lungs retrieved after 4 hours of in situ oxygen ventilation followed by 4 hours of hypothermic storage. Nonventilated cadaver lungs had substantially less viability. Adenosine triphosphate levels were significantly higher in the control group than in the oxygen-ventilated group, which were higher still than those in the nonventilated group. Adenosine triphosphate levels were consistently higher in University of Wisconsin solution-flushed lungs compared with Euro-Collins solution-flushed lungs in all groups. Total adenine nucleotide levels had a similar pattern. Wet-to-dry ratios were significantly lower in the control group (Euro-Collins = 6.27 +/- 0.46, University of Wisconsin = 4.63 +/- 0.07) compared with the oxygen-ventilated (Euro-Collins = 9.80 +/- 0.44, University of Wisconsin = 10.96 +/- 0.60) and nonventilated (Euro-Collins = 9.44 +/- 0.26, University of Wisconsin = 11.54 +/- 1.16; p < 0.0001) groups. CONCLUSIONS: Four hours of circulatory arrest before 4 hours of hypothermic storage had no additional adverse impact on lung viability compared with lungs subjected to 4 hours of hypothermic storage alone, provided nonperfused lungs were ventilated with 100% oxygen. Adenine nucleotide levels were well maintained in oxygen-ventilated cadaver lungs, more so in University of Wisconsin solution-flushed lungs compared with Euro-Collins solution-flushed lungs.

Adenine Nucleotides↗
PubMed1996

Donor lungs from ventilated cadavers: impart of a free radical scavenger.

BACKGROUND: The shortage of donors for lung transplantation may be alleviated with the use of lungs retrieved from cadavers. The purpose of this study was to determine whether a free radical scavenger, dimethylthiourea, would improve the function of lungs retrieved from ventilated cadavers. METHODS: Left lung transplantation was performed in 21 dogs. Donors were sacrificed then ventilated with 100% oxygen. After 2 hours, donor lungs were flushed in a blinded fashion with 2 L of modified Euro-Collins solution, with either dimethylthiourea (n = 10) or saline solution (n = 11) added, then harvested. A donor right lung lobe was perfused with trypan blue vital dye to assess cell viability at harvest and after the transplantation. Percentage of nonviability was similar in the dimethylthiourea and control groups (13 versus 20 at retrieval and 38 versus 41 at graft reperfusion). After transplantation, the right pulmonary artery and bronchus were occluded, rendering the recipient on the pulmonary graft. The recipient's lungs were ventilated for 8 hours, with the inspired oxygen fraction maintained at 0.4. RESULTS: Seven of ten dogs in the dimethylthiourea group survived the 8-hour period, compared with 4 of 11 dogs in the control group. Compared with the control survivors (n = 4) at 8 hours after the operation, the dimethylthiourea survivors (n = 7) had a higher mean arterial oxygen pressure (144 +/- 21 versus 98+/- 12 mm Hg) and cardiac output (2.2 +/- 0.2 versus 1.6 +/- 0.2 L/min) and a lower mean pulmonary vascular resistance (946 +/- 96 versus 1414 +/- 128 dynes.sec-1.cm5, p < 0.05) and extravascular lung water (10.6 +/- 1.2 versus 12.3 +/- 3.2 ml/kg). Differences between groups during the 8-hour period were usually insignificant. CONCLUSIONS: This model imposes a rigorous challenge to the single transplanted lung, and yet cadaver lungs still supported life in half of the recipients. Dimethylthiourea may confer a benefit to recipients of cadaver lungs.

Animals↗
PubMed1995

When does the lung die? Time course of high energy phosphate depletion and relationship to lung viability after "death".

The shortage of lung donors for clinical transplantation could be significantly alleviated if lungs could be retrieved from cadavers hours after death. However, the time course of loss of lung viability after circulatory arrest and organism death remains unclear. To determine postmortem adenine nucleotide tissue levels in the lung and their relationship to lung viability, Sprague-Dawley rats were sacrificed and then ventilated with 100% oxygen (n = 50, O2) or 100% nitrogen (n = 40, N2) or left nonventilated (n = 50). Lungs from control rats (n = 20) were retrieved immediately after sacrifice. Lungs in the three study groups were retrieved at successive intervals postmortem. Adenine nucleotides (ATP, ADP, and AMP) and hypoxanthine and xanthine metabolites of adenosine were extracted from lung tissue and measured using high-performance liquid chromatography. Pulmonary parenchymal cell viability was quantified by pulmonary artery infusion of trypan blue vital dye in the contralateral lung of each animal. By 4 hr postmortem, viability was 85 +/- 1% in the O2-ventilated cadaver rat lungs, significantly higher than in the N2-ventilated (43 +/- 8%) and in the nonventilated (48 +/- 4%) lungs, where the percentage of viable cells was similar. All of the groups showed a time-dependent decrement in ATP levels and total adenine nucleotide (TAN) levels after death, but this was markedly attenuated in O2-ventilated cadaveric rat lung.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenine Nucleotides↗
PubMed1995

Post-translational processing of the highly processed, secreted periplasmic carbonic anhydrase of Chlamydomonas is largely conserved in transgenic tobacco.

The periplasmic carbonic anhydrase (CA) gene CAH1 of Chlamydomonas reinhardtii codes for a highly processed secreted glycoprotein. The primary translation product of the CAH1 gene is targeted to the ER, where it is proteolytically processed to yield two different subunits, glycosylated, assembled into an active heterotetramer, and secreted. After replacing the target leader sequence with that from tobacco anionic peroxidase, expression of this gene in transgenic tobacco plants was investigated. SDS-PAGE gels of the purified protein from tobacco, showed that it migrated as a series of discrete bands (two large and one small) with slightly faster mobility than the comparable bands in the purified algal protein. The expressed protein in the plant was active, and staining with thymol and sulfuric acid confirmed that it was also glycosylated. The periplasmic CA1 (peri-CA1) also was found to be enriched in the intercellular fluid of transgenic tobacco, indicating it was secreted. The specific activity of the enzyme and its sensitivity to sulfonamide inhibitors were similar to that of the native algal enzyme. These results suggest that the post translational processing of Chlamydomonas peri-CA1 is largely conserved in a higher plant.

Animals↗