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Biomedical subjects

D R Larson

Publications and source records attributed to D R Larson.

At least 19 recordsLinked to original sources
PubMed2007

Results at up to 20 years after ileal pouch-anal anastomosis for chronic ulcerative colitis.

BACKGROUND: Ileal pouch-anal anastomosis (IPAA) is performed routinely for chronic ulcerative colitis. METHODS: Using data from a prospective database and annual standardized questionnaires, functional outcome, complications and quality of life (QoL) after IPAA were assessed. RESULTS: Some 1885 IPAA operations were performed for chronic ulcerative colitis over a 20-year period (mean follow-up 11 years). The mean age at the time of IPAA was 34.1 years, increasing from 31.2 years (1981-1985) to 36.3 years (1996-2000). The overall rate of pouch success at 5, 10, 15 and 20 years was 96.3, 93.3, 92.4 and 92.1 per cent respectively. Mean daytime stool frequency increased from 5.7 at 1 year to 6.4 at 20 years (P < 0.001), and also increased at night (from 1.5 to 2.0; P < 0.001). The incidence of frequent daytime faecal incontinence increased from 5 to 11 per cent during the day (P < 0.001) and from 12 to 21 per cent at night (P < 0.001). QoL remained unchanged and 92 per cent remained in the same employment. Seventy-six patients were eventually diagnosed with indeterminate colitis and 47 with Crohn's disease. CONCLUSION: IPAA is a reliable surgical procedure for patients requiring proctocolectomy for chronic ulcerative colitis and indeterminate colitis. The clinical and functional outcomes are excellent and stable for 20 years after operation.

Adolescent↗
PubMed2003

Long-term follow-up of IgM monoclonal gammopathy of undetermined significance.

The current study was conducted to determine the risk of adverse outcomes among patients with monoclonal gammopathy of undetermined significance (MGUS) of the IgM class. Two hundred thirteen patients with IgM MGUS were identified in southeastern Minnesota from 1960 to 1994. The primary end point was progression to lymphoma or a related disorder assessed by the Kaplan-Meier method. Patients were followed for a total of 1,567 person-years (median, 6.3 years per subject). Seventeen patients developed lymphoma (relative risk [RR], 14.8) and six progressed to Waldenstrom's macroglobulinemia (RR, 262), while three developed primary amyloidosis (RR, 16.3) and three others had chronic lymphocytic leukemia (RR, 5.7). The relative risk of progression was 16-fold higher in the IgM MGUS patients compared to the white population of the Iowa Surveillance, Epidemiology, and End Results (SEER) program. The risk of progression of MGUS of IgM type to lymphoma or related disorders averaged 1.5% per year throughout the period of observation.

Aged↗
PubMed2001

Eligibility for hematopoietic stem-cell transplantation for primary systemic amyloidosis is a favorable prognostic factor for survival.

PURPOSE: Based on the success of hematopoietic stem-cell transplantation (HSCT) for multiple myeloma, HSCT is being used to treat patients with primary systemic amyloidosis (AL). This article addresses the extent to which eligibility to undergo HSCT is a favorable prognostic feature and explores prognostic factors within the subset of eligible patients. PATIENTS AND METHODS: The Mayo Clinic amyloid database was queried for all patients with AL seen at the Mayo Clinic from 1983 through 1997 who would have been eligible for peripheral-blood stem-cell transplantation. Inclusion criteria included biopsy-proven amyloid, symptomatic disease, absence of a clinical diagnosis of multiple myeloma, age < or = 70 years, cardiac interventricular septal thickness < or = 15 mm, cardiac ejection fraction more than 55%, serum creatinine < or = 2 mg/dL, and direct bilirubin < or = 2.0 mg/dL. RESULTS: Median age was 56 years (range, 25 to 70) with 79 (34%) older than 60 years. One hundred patients had early cardiac involvement; 41, hepatic involvement; 167, renal involvement; and 39, nerve involvement. The 229 patients have had a median follow-up of 52 months, and 151 have died. The median survival was 42 months with 5- and 10-year survival rates of 36% and 15%, respectively. Important predictors of survival were size of M-component in 24-hour urine, number of involved organs, alkaline phosphatase, performance score, and weight loss. CONCLUSION: The same patients who are eligible for HSCT are a good-risk population who do relatively well with chemotherapy (median survival, 42 months), substantially better than the expected median survival of 18 months for all patients with AL. A randomized trial is needed to assess the true effect of HSCT.

Adult↗
PubMed2001

Laparoscopic ultrasonography: a training model.

PURPOSE: The purpose of this study was to develop a surgical training program and to test the accuracy of laparoscopic ultrasound in detecting injected lesions in pig livers. METHODS: Pig livers were divided into eight segments and injected with Surgilube "malignant" and silicone "benign" lesions. All were examined by laparoscopic ultrasound followed by liver explantation to confirm results. First, a pilot study was conducted on six swine by injecting Surgilube lesions and performing laparoscopic ultrasound through 3 different ports (left upper quadrant (I), umbilicus (II), and right lower quadrant (III)) to determine per-segment accuracy and to optimize port placement. Second, blinded injection of Surgilube and silicone implants was done on 18 pigs with laparoscopic ultrasound conducted through the two most accurate ports from the pilot study. This model was then tested during a resident training workshop. RESULTS: In the pilot study, per-lesion and per-segment sensitivity was 96 percent, with no difference among the three ports used. Ports I and II were chosen for the blinded study for their convenience in performing laparoscopic colectomy. In the blinded study, per-segment sensitivity, specificity, and accuracy were 97 percent, 94 percent, and 96 percent and 99 percent, 94 percent, and 97 percent for ports I and II, respectively. At the conclusion of a pilot workshop, trainee per-segment sensitivity, specificity, and accuracy were 60 percent, 80 percent, and 70 percent, respectively. The major difficulty was differentiating benign from malignant lesions. CONCLUSIONS: A useful liver laparoscopic ultrasound training model for surgeons was developed with good preliminary results. It is anticipated that further training will enhance laparoscopic ultrasound accuracy rates before application of this modality in humans.

Animals↗
PubMed2001

A preliminary analysis of psychophysiological variables and nursing performance in situations of increasing criticality.

OBJECTIVE: To examine the relationship between psychological, physiological, and performance variables in intensive care unit (ICU) nurses in situations of increasing criticality. SUBJECTS AND METHODS: Psychophysiological variables and endotracheal suctioning performance were examined in a classroom, a skills laboratory, and an ICU. Situation-specific anxiety (state anxiety) and the predisposition to view situations as threatening (trait anxiety), cognitive appraisal, and heart rate were measured and compared with self-appraisal and a nurse instructor's ratings of suctioning performance. Baseline data were obtained during class on 45 novice ICU nurses. RESULTS: Twenty-six nurses provided complete data, which included being videotaped and monitored in the classroom, in the skills laboratory performing endotracheal suctioning, and in the ICU during suctioning. High state anxiety significantly predicted poor ICU suctioning performance (P<.04). Nurses high in state and trait anxiety, worry, and heart rate performed poorly compared with less anxious nurses. Nurses in this study who performed best had a mean heart rate of 94 beats/min. CONCLUSION: Those nurses who are high state anxious, high trait anxious, and worried and who had a faster heart rate performed less well than their more relaxed peers. Nurses with high state anxiety may be at risk for attrition, burnout, medical errors, and poor performance in other ICU nursing tasks.

Anxiety↗
PubMed2000

Repositioning error in low back pain. Comparing trunk repositioning error in subjects with chronic low back pain and control subjects.

STUDY DESIGN: Repositioning error of the trunk was tested in 20 subjects with chronic low back pain and in 20 control subjects. The 3Space Tracker (Polhemus, Colchester, VT), a device that measures three-dimensional position in space, was used to determine the subject's trunk position. OBJECTIVES: To determine whether repositioning error is different in subjects with chronic low back pain than in control subjects. SUMMARY OF BACKGROUND DATA: Proprioception allows the body to maintain proper orientation during static and dynamic activities. In peripheral joint injuries, researchers have demonstrated a loss of some aspects of proprioception and improvement in outcome with retraining. Although the components of proprioception in subjects with low back pain have not been well studied, it is thought that these persons lose some elements of proprioception that can be measured in a quantifiable way. If so, then rehabilitation to improve these deficits is important. In this pilot study, one aspect of proprioception, repositioning error, was examined. METHODS: The subjects attempted to replicate target positions of the trunk in flexion, extension, lateral bending, and lateral rotation. Repositioning error was calculated as the absolute difference between the actual and the subject-replicated target positions. RESULTS: No significant difference was found in repositioning error between the control subjects and the persons with chronic low back pain. CONCLUSIONS: Because proprioception is complex and entails the use of many afferent receptors, it is difficult to measure any one afferent deficiency discretely. The authors believe that this study, in which one aspect of proprioception was measured in an indirect manner, provides important background information on low back position sense. Further studies analyzing aspects of proprioception in subjects with low back pain are recommended.

Adult↗
PubMed2000

Safety and advantages of laparoscopic vs. open colectomy in the elderly: matched-control study.

PURPOSE: The aim of this study was to determine rates of complications and extent of benefits for laparoscopic-assisted colectomy compared with open colectomy in patients older than age 75. METHODS: Forty-two patients undergoing laparoscopic-assisted colectomy (1992-1998) were matched to 42 open colectomy patients for gender, age, year of surgery, operating surgeon, and procedure. Health status (American Society of Anesthesiology score), previous abdominal surgery, conversion rate, surgical outcome, and need for assistance at admission and dismissal (independence vs. home with assistance vs. nursing facilities) were reviewed. RESULTS: Mean ages were 81.2 and 80.5 years for laparoscopic-assisted colectomy and open colectomy, respectively (P = not significant). Twenty-one laparoscopic-assisted colectomy and 23 open colectomy patients were females. American Society of Anesthesiology scores were comparable, as were rates of previous abdominal surgery (57 percent for laparoscopic-assisted colectomy vs. 62 percent for open colectomy; P = not significant). Mean operative times were longer for laparoscopic-assisted colectomy (190 minutes for laparoscopic-assisted colectomy vs. 142 minutes for open colectomy; P < 0.001); operating room times progressively decreased from 221 minutes in 1992 to 1995 to 147 in 1998 for laparoscopic right hemicolectomy (P < 0.001). The conversion rate for laparoscopic-assisted colectomy was 14.3 percent. There were no deaths in either group, and laparoscopic-assisted colectomy was associated with fewer morbidities (14.3 percent for laparoscopic-assisted colectomy vs. 33.3 percent for open colectomy; P = 0.04), narcotic usage (2.7 vs. 4.8 days; P < 0.001), time to return to bowel movements (3.9 vs. 5.9 days; P < 0.001), and length of hospital stay (6.5 vs. 10.2 days; P < 0.001). Independent status at admission in 37 laparoscopic-assisted colectomy and 38 open colectomy patients was maintained at discharge by 35 laparoscopic-assisted colectomy vs. 29 open colectomy patients (P = 0.025). CONCLUSIONS: Laparoscopic-assisted colectomy is safe and beneficial, including preservation of postoperative independence, to the elderly when compared with open colectomy.

Aged↗
PubMed2000

Biomechanical evaluation of occipital fixation.

Many studies have shown a positive correlation among screw pullout strength, screw insertional torque, bone thickness, and areal bone mineral density (BMD) measured by dual-energy X-ray absorptiometry. Variations are significant in the anatomy of the occipital bone. But no studies have correlated these variables with respect to the two locations commonly used for plate fixation to the occiput. The purpose of this study was to determine the thickness and quality of the occipital bone and to correlate these variables with the insertional torque of screws and the pullout strength of plates secured into two different locations on the occiput. The occiputs of 12 adult human fresh frozen cadaveric specimens were used. The specimens were analyzed by dual-energy X-ray absorptiometry. Direct thickness measurements of the occiput were performed. Areal and volumetric BMD were measured. A simple pelvic reconstruction plate (3.2 mm) was fixed to the occiput either laterally or at the midline with bicortical 4-mm cancellous screws. Torque was recorded at the time of insertion of each screw. Axial pullout tests were performed on all specimens. The peak load, failure load, stiffness, and energy to failure were recorded for each construct. Statistical analysis showed that the average thickness of occipital bone is greater in the midline than laterally. Occipital bone is thicker and screw torque is greater close to the inion. There is a positive correlation between bone thickness, areal BMD as measured by dual-energy X-ray absorptiometry, screw insertional torque, and strength of fixation. A plate fixed in the midline region of the occiput provides more rigid fixation than a plate fixed laterally. Areal BMD correlates better than volumetric BMD with bone thickness and is a reliable predictor of the strength of occipital fixation.

Absorptiometry, Photon↗
PubMed2000

Biological activity of rhBMP-2 released from PLGA microspheres.

Human recombinant bone morphogenetic protein-2 (rhBMP-2) has been proven effective in stimulating the regeneration of bone in both skeletal and extraskeletal locations. Through encapsulation within, and release from, biodegradable poly(DL-lactic-co-glycolic acid) (PLGA) microspheres, a proven vehicle for sustained delivery of various proteins, the local concentrations of rhBMP-2 could be maintained at optimal levels to stimulate bone regeneration and remodeling at the site of healing in diverse clinical settings. Thus the purpose of this work was to investigate the encapsulation of rhBMP-2 in PLGA microspheres and its biologic activity upon release. Using in vitro tests in simulated body fluids, the effect of rhBMP-2 released from PLGA microspheres upon osteoblast cell cultures was found to be statistically similar to the effect produced by positive controls consisting of nonencapsulated aqueous rhBMP-2 in simulated body fluids. This clarifies an important step in skeletal tissue engineering strategies aimed at the use of encapsulated rhBMP-2 to stimulate bone regeneration and remodeling.

Biocompatible Materials↗
PubMed2000

Effects of 4 hand-drying methods for removing bacteria from washed hands: a randomized trial.

OBJECTIVE: To evaluate the effects of 4 different drying methods to remove bacteria from washed hands. SUBJECTS AND METHODS: One hundred adult volunteers participated in this randomized prospective study. All bacterial counts were determined using a modified glove-juice sampling procedure. The difference was determined between the amounts of bacteria on hands artificially contaminated with the bacterium Micrococcus luteus before washing with a nonantibacterial soap and after drying by 4 different methods (cloth towels accessed by a rotary dispenser, paper towels from a stack on the hand-washing sink, warm forced air from a mechanical hand-activated dryer, and spontaneous room air evaporation). The results were analyzed using a nonparametric analysis (the Friedman test). By this method, changes in bacterial colony-forming unit values for each drying method were ranked for each subject. RESULTS: The results for 99 subjects were evaluable. No statistically significant differences were noted in the numbers of colony-forming units for each drying method (P = .72). CONCLUSION: These data demonstrate no statistically significant differences in the efficiency of 4 different hand-drying methods for removing bacteria from washed hands.

Adult↗
PubMed2000

Primary fibrosarcoma of bone. Outcome after primary surgical treatment.

To investigate outcome and evaluate prognostic factors in primary fibrosarcoma of bone, all patients at the authors' institution who had surgical treatment for primary fibrosarcoma of bone from 1910 to 1995 were studied. Medical records, surgical reports, radiographs, and histologic slides of 92 patients (51 males, 41 females; mean age, 38 years; range, 8-84 years) were reviewed. The most common tumor locations were the femur (28 patients), tibia (21 patients), and pelvis (14 patients). Sixty-one tumors (66%) were Enneking Stage IIB. Twenty-nine patients (31.5%) had adjuvant therapy: 16 had radiation, nine had chemotherapy alone, and four had radiation and chemotherapy. Amputation or disarticulation was performed in 61 patients (66%), wide excision was performed in 13 (14%), marginal excision was performed in 15 (16%), and intralesional excision was performed in three (3.3%). Local recurrence occurred in 14 patients (15%) at a median time of 7 months (range, 3-21 months). Metastases developed in 58 of the 85 patients (68%) with Stage I or II tumors at presentation, at a median of 9 months (range, 1-51 months). Survivorship analysis showed that the overall probability of survival was 33.4% at 5 years after surgery. Multivariate analysis showed that the main prognostic risk factors affecting overall survival included age older than 40 years, tumor location in the axial skeleton, and high-grade tumor (Grade 3 or 4). With the high incidence of systemic failure after surgical treatment, perioperative adjuvant treatment modalities should be considered.

Adolescent↗
PubMed1999

Time course of histological progression in primary sclerosing cholangitis.

OBJECTIVE: The aim of this study was to determine the time course over which patients with primary sclerosing cholangitis (PSC) progress through the histological stages of the disease. METHODS: One hundred seven patients with PSC who had at least two liver biopsies were identified. The stage information from two consecutive biopsies formed one observation and a continuous time Markov model was used to describe the rate of progression between biopsies. RESULTS: Three hundred seven liver biopsies were performed in the 107 patients giving a total of 200 observations. At 1 yr, 42% of patients in stage II disease progress, 66% at 2 yr, and 93% at 5 yr; whereas 14% of patients in stage III progress at 1 yr, 25% at 2 yr, and 52% at 5 yr. The frequency of progression of stage I disease could not be determined because of the small number of patients in stage I. Regression of histological stage was observed in 30 of 200 total observations (15%), and in 30 of 85 observations (35%) in which there was a change in stage. CONCLUSIONS: These data regarding histological progression in PSC may be potentially helpful in determining the number of patients and length of time necessary to appreciate a treatment effect in clinical trials. However, the high degree of sampling variability in PSC may restrict the usefulness of serial liver biopsies as a means of evaluating treatment efficacy.

Adolescent↗
PubMed1999

Head and neck replacement prostheses in revision hip arthroplasty: experience with a single modern design.

This study reviewed 52 revision hip arthroplasties in which calcar cortical deficiencies were addressed by implantation of a cemented, modern-design head and neck replacement femoral prosthesis. Mean clinical follow-up was 38 months. Radiographic follow-up beyond 22 months was available for 34 patients (mean: 35.8 months). Mean Mayo clinical hip score (maximum: 80) improved from 28.2 preoperatively to 55.2 at last follow-up. No femoral component was revised for aseptic loosening. However, radiographic analysis demonstrated one prosthesis was probably loose and two were possibly loose. A 92.7% Kaplan-Meier 5-year implant survival rate free from radiographic loosening was projected. This type of prosthesis has yielded good clinical results and excellent early survival.

Adult↗
PubMed1999

Determinants of plasma fibrin D-dimer sensitivity for acute pulmonary embolism as defined by pulmonary angiography.

BACKGROUND: The reported operating characteristics of the plasma fibrin D-dimer level for the diagnosis of acute pulmonary embolism vary widely. OBJECTIVE: To determine the sensitivity, specificity, predictive value, and clinical utility of the D-dimer for the diagnosis of pulmonary embolism, and to describe the effect of D-dimer assay method (enzyme-linked immunosorbent assay [ELISA], latex agglutination, membrane ELISA) and discriminate level, patient location at onset, comorbid disease, duration and intensity of concurrent heparin administration, and duration of symptoms on these operating characteristics. DESIGN: Prospective laboratory investigation. SETTING: Community and tertiary care teaching hospital. PATIENTS: Consecutive patients with suspected acute pulmonary embolism referred for pulmonary angiography from April 1993 through March 1996. MEASUREMENTS: Baseline characteristics, the duration and intensity of heparin anticoagulation, the time interval between symptom onset and plasma D-dimer testing, pulmonary angiography, and the D-dimer level on the day of pulmonary angiography. RESULTS: Of 105 consenting patients, 33 (31%) had a positive pulmonary angiogram. The D-dimer sensitivity/ negative predictive value for the ELISA, latex agglutination (American Bioproducts Co/Diagnostica Stago and Biopool International), and membrane ELISA were 100%/100%, 94%/94%, 100%/100%, and 97%/96%, respectively, at a discriminate level of 250 microg/L or less. The clinical utility, defined as the prevalence of a negative test, ranged from 17% to 33%. D-dimer sensitivity was unaffected by patient location at onset, comorbid disease, or heparin therapy but was inversely related to the duration of symptoms. CONCLUSIONS: The sensitivity of the plasma fibrin D-dimer for the diagnosis of pulmonary embolism depends on the assay method, the assay-specific discriminate level, and the duration of symptoms. At the appropriate discriminate level, the plasma D-dimer is a sensitive but nonspecific test for the diagnosis of pulmonary embolism.

Aged↗
PubMed1999

Incidence of postpartum depression in Olmsted County, Minnesota. A population-based, retrospective study.

OBJECTIVE: To provide population-based data on the recognition of postpartum depression by reviewing diagnostic and treatment practices of all physicians caring for pregnant and postpartum women in Olmsted County, Minnesota. STUDY DESIGN: We reviewed the medical charts of a random sample of 403 Olmsted County women who gave birth in 1993. Using outpatient and hospital medical records, we recorded all documented symptoms and diagnoses of depression, drug therapy for depression and variables that were previously associated with postpartum depression, during pregnancy and for one year postpartum. RESULTS: Fifteen (3.7%) of the women were identified as having postpartum depression during the year following delivery. Two (0.5%) other women had preexisting depression that did not remit before delivery. We found significant associations between postpartum depression and young maternal age, single marital status, hyperemesis gravidarum, tobacco or illegal drug use during pregnancy, history of substance abuse, high utilization of emergency department services and previous affective disorder. Using multivariate analysis with stepwise logistic regression, only single marital status, previous affective disorder and high utilization of emergency services remained associated with postpartum depression. CONCLUSION: The incidence of postpartum depression was significantly below incidences seen in prospective studies. Systematic screening for postpartum depression may be appropriate in this population.

Adult↗
PubMed1998

Long-term trends in hip fracture prevalence: the influence of hip fracture incidence and survival.

In this population-based descriptive study covering the 65-year period, 1928-92, there was a 5-fold increase in hip fracture prevalence among Rochester, Minnesota residents between 1928-42 and 1973-82, from 135.8 to 675.8 per 100,000. This change was dictated almost entirely by an increase in the incidence of first hip fractures due to moderate trauma (n = 2058) that was observed among Rochester women through 1950, and among men through 1980, that affected all age groups. Declining incidence rates thereafter led to a 9% fall in hip fracture prevalence from 1973-82 to 1983-92 to a rate of 612.7 per 100,000. A 13.7-year increase in age at first hip fracture over the study period was accounted for by aging of the underlying population, and a comparable 13.9-year increase in the age at death following hip fracture appeared to result from improved survival in the population generally. Thus, trends in hip fracture prevalence were mainly determined by changes in incidence rather than relative changes in age at onset and death following hip fracture.

Adult↗
PubMed1998

Thyroid cancer in patients with familial adenomatous polyposis.

The association between thyroid cancer and familial adenomatous polyposis (FAP), albeit rare, is well known. It has been suggested that the thyroid tumors have unique histologic characteristics and may be follicular in origin. Because of their rarity, treatment and long-term prognosis are uncertain. Twelve such patients (prevalence 399/100,000) seen during 1949-1995 were retrospectively reviewed. Histology was independently re-reviewed by two pathologists. There were 11 female patients (two sisters) and 1 male patient, with a mean age of 28 years (range 15-61 years). Eight patients (66%) had multicentric tumors and five (42%) bilateral disease. Average tumor diameter was 1.8 cm (range 0.2-5.0 cm). Regional nodal metastases were present in two patients. All 12 thyroid cancers in this series were papillary. The one male patient demonstrated "typical" histology with variable papillary and follicular architecture, whereas the 11 female patients had tumors with unusual histology as described by Harach. Five patients (41%) were treated by total thyroidectomy, five with near-total thyroidectomy, and two with lobectomy alone. Mean follow-up was 142 months (range 7 months to 30 years). Regional recurrent disease occurred in two patients, one of whom died of the disease. The 5- and 20-year survivals were 90% and 77%, respectively. The results indicated that all tumors in this study were papillary, although atypical histology was encountered in 91%. The mean age (28 years) is younger than that of patients with sporadic disease. Multicentricity and bilateral disease are common. In view of this finding, total thyroidectomy should be strongly considered. Long-term prognosis is excellent. The finding of unusual histology in a young patient with papillary thyroid carcinoma should arouse the suspicion of FAP.

Adolescent↗