Applying machine learning methods for the analysis of two-dimensional mass spectra.

In a measurement of isomeric yield-ratios in fission, the Phase-Imaging Ion-Cyclotron-Resonance technique, which projects the radial motions of ions in the Penning trap (JYFLTRAP) onto a position-sensitive micro-channel plate detector, has been applied. To obtain the yield ratio, that is the relative population of two states of an isomer pair, a novel analysis procedure has been developed to determine the number of detected ions in each state, as well as corrections for the detector efficiency and decay losses. In order to determine the population of the states in cases where their mass difference is too small to reach full separation, a Bayesian Gaussian Mixture model was implemented. The position-dependent efficiency of the micro-channel plate detector was calibrated by mapping it with 133Cs+ ions, and a Gaussian Process was trained with the position data to construct an efficiency function that could be used to correct the recorded distributions. The obtained numbers of counts of excited and ground-state ions were used to derive the isomeric yield ratio, taking into account decay losses as well as feeding from precursors.

Quantitative chromogenic immunohistochemical image analysis in cellprofiler software.

Visual grading of chromogenically stained immunohistochemical (IHC) samples is subjective, time consuming, and predisposed to considerable inter- and intra-observer variations. The open-source digital analysis software, CellProfiler has been extensively used for fluorescently stained cells/tissues; however, chromogenic IHC staining is routinely used in both pathological and research diagnostics. The current investigation aimed to compare CellProfiler quantitative chromogenic IHC analyses against the gold standard manual counting. Oral mucosal biopsies from patients with chronic graft-versus-host disease were stained for CD4. Digitized images were manually counted and subjected to image analysis in CellProfiler. Inter-observer and inter-platform agreements were assessed by scatterplots with linear regression and Bland-Altman plots. Validation comparisons between the manual counters demonstrated strong intra-observer concordance (r2 = 0.979), particularly when cell numbers were less than 100. Scatterplots and Bland-Altman plots demonstrated strong agreement between the manual counters and CellProfiler, with the number of positively stained cells robustly correlating (r2 = 0.938). Furthermore, CellProfiler allowed the determination of multiple variables simultaneously, such as area stained and masking to remove any nonstained tissue and white gaps, which also demonstrated reliable agreement (r2 = >0.9). CellProfiler demonstrated versatility with the ability to assess large numbers of images and allowed additional parameters to be quantified. CellProfiler allowed rapid high processing capacity of chromogenically stained chronic inflammatory tissue that was reliable, accurate, and reproducible and highlights potential applications in research diagnostics.

Osteoporosis knowledge among individuals with recent fragility fracture.

BACKGROUND: To evaluate osteoporosis knowledge among patients with fractures and to evaluate factors associated with osteoporosis knowledge. METHODS: Patients with fragility fractures participated in a telephone interview. Participants were asked what they thought osteoporosis was. Unadjusted odds ratios (OR, 95% CI) were calculated to identify factors associated with a correct definition. Predictors identified in univariate analysis were entered into multivariable logistic regression models. A subset also completed the Facts on Osteoporosis Quiz. RESULTS: One hundred twenty-seven patients (82% women) participated in the study, with mean (SD) age being 67.5 (12.7) years. Ninety-five (75%) respondents gave correct osteoporosis definitions. The odds of an individual providing a correct definition of osteoporosis were higher for those who reported a diagnosis of osteoporosis or those who reported higher education levels, but the odds decreased with increasing age. A total of 49 (39%) respondents completed the Facts on Osteoporosis Quiz; the average score was 13.6 (3.8) of 21. Areas that respondents scored poorly on were related to key risk factors. CONCLUSION: Many patients with fractures are unaware of important risk factors. Education initiatives aimed at improving osteoporosis knowledge should be directed at individuals at high risk of fracture. Nurses and other allied healthcare providers working in fracture clinics, acute care, and rehabilitation settings are in an ideal position to communicate information about osteoporosis and fracture risk to individuals with a recent fragility fracture.

Osteoporosis risk perceptions among patients who have sustained a fragility fracture.

OBJECTIVE: To explore the perceptions of patients who have sustained a fragility fracture regarding their future fracture risk and the beliefs underlying their perceptions. METHODS: Patients with fragility fracture participated in a telephone interview. Quantitative and qualitative methods were used to characterize patient characteristics and perspectives of future fracture risk. Content analysis of qualitative statements was independently performed by three investigators to identify common themes and contrasting statements, and the findings were discussed to ensure consensus. RESULTS: Consistent themes were identified among participant responses irrespective of whether they responded "yes", "no" or "unsure" when asked whether they were at increased fracture risk: (1) patients' perception of risk was influenced by whether or not they believed they had osteoporosis, which may be altered by interaction with health care providers; (2) patients' had their own perceptions of their bone health; (3) patients' attributed their risk to their own actions or "carefulness"; and (4) patients' had specific beliefs about their fracture and determinants of fracture risk. CONCLUSION: Patients who experience fragility fractures develop perceptions about future fracture risk that are influenced by interactions with health care providers, as well as beliefs about their fracture and beliefs that they can modify their risk. PRACTICE IMPLICATIONS: Health care providers should discuss strategies for fracture prevention with all patients after fragility fracture to ensure that patients understand that participation in preventative behaviours can modify their risk.

Sequential bilateral total knee arthroplasty under 1 anesthetic in patients > or = 75 years old: complications and functional outcomes.

The objectives of this study were to determine the perioperative surgical and medical risks associated with sequential bilateral total knee arthroplasty (TKA) in patients > or = 75 years old and to assess their functional status and overall level of satisfaction at follow-up. Study participants were 82 consecutive patients > or = 75 years old who underwent a sequential bilateral TKA and 82 matched patients who underwent a unilateral TKA. There were 46 postoperative complications in the bilateral TKA group compared with 27 in the unilateral TKA group (P = .003). Postoperative cardiovascular complications were significantly greater in the sequential bilateral TKA group and were associated significantly with preoperative cardiovascular comorbidity. The mean Modified Hospital for Special Surgery knee score was rated as good (mean, 63.5 out of 80), and 95% of patients rated their knees as excellent or good at follow-up. Sequential bilateral TKA in patients > or =75 years old results in high patient satisfaction and good functional status at follow-up; however, there is an increased risk of cardiovascular complications during the postoperative period in bilateral sequential TKA patients when compared with a matched cohort of unilateral TKA patients.

The efficacy of low-pressure lavage with different irrigating solutions to remove adherent bacteria from bone.

BACKGROUND: Recent studies have suggested that high-pressure irrigation may have adverse effects on bone. However, the use of low-pressure irrigation may not remove all adherent bacteria from bone. The type of irrigating solution may be an important factor in the removal of adherent bacteria with pulsatile lavage. In this study, we compared the effects of various irrigating solutions on the number and function of osteoblasts and osteoclasts and we examined the effectiveness of these solutions in removing adherent bacteria from bone. METHODS: To examine the effect of irrigating solutions on the number and activity of osteoblasts, we isolated calvarial cells from newborn C57BI/6 mice and exposed the cells to equivalent concentrations of ethanol, povidoneiodine, liquid soap, antimicrobial wash (50 U/L of bacitracin), or chlorhexidine gluconate, for two, ten, or twenty minutes. The cells were then cultured in the presence of bone-nodule-enhancing medium (beta-glycerophosphate and ascorbic acid) for twenty-one days. The medium was changed every three or four days. Mineralized nodules were stained with alizarin red S, and osteoblasts were stained with a histochemical stain for alkaline phosphatase. Osteoclasts were identified with tartrate-resistant acid-phosphatase staining. In a second experiment, canine cortical tibiae were contaminated with Staphylococcus aureus for six hours and subjected to different irrigating solutions with or without low-pressure lavage. Bacterial colony-forming units were quantitated under each set of conditions. RESULTS: Each solution resulted in a time-dependent decrease in the number of calvarial osteoblasts and osteoclasts compared with that in the controls. The 1% soap solution resulted in greater preservation of both alkaline-phosphatase activity and bone-nodule formation than did the other solutions. Moreover, the soap solution preserved the number of osteoclasts to the greatest extent. The povidone-iodine and chlorhexidine-gluconate solutions resulted in the largest decline in bone-nodule formation, alkaline-phosphatase activity, and number of osteoclasts. Low-pressure pulsatile lavage with the soap solution removed the most bacteria from the contaminated tibia when compared with either the soap solution alone or low-pressure irrigation with saline solution. CONCLUSIONS: Our findings suggest that certain solutions may be more effective in removing bacteria from bone than mechanical irrigation with saline solution alone. Among the various solutions examined, the soap solution preserved the number and activity of osteoblasts the most. Low-pressure lavage with the soap solution resulted in the greatest removal of adherent bacteria from bone.

Reamed versus nonreamed intramedullary nailing of lower extremity long bone fractures: a systematic overview and meta-analysis.

OBJECTIVE: To determine the effect of reamed versus nonreamed intramedullary (IM) nailing of lower extremity long bone fractures on the rates of nonunion, implant failure, malunion, compartment syndrome, pulmonary embolus, and infection. DESIGN: Quantitative systematic review of prospective, randomized controlled trials. DATA IDENTIFICATION: MEDLINE and SCISEARCH computer searches provided lists of published randomized clinical trials from 1969 to 1998. Extensive hand searches of major orthopaedic journals, bibliographies of major orthopaedic texts, and personal files identified additional studies. STUDY SELECTION AND DATA EXTRACTION: Of 676 citations initially identified, sixty proved potentially eligible, of which four published and five unpublished randomized trials met all eligibility criteria. Each of three investigators assessed study quality and abstracted relevant data. RESULTS: The pooled relative risk of reamed versus nonreamed nails (nine trials, n = 646 patients) was 0.33 [95% confidence interval (CI), 0.16 to 0.68; p = 0.004]. The absolute risk difference in nonunion rates with reamed IM nailing was 7.0 percent (95% CI, 1 to 11 percent). Thus, one nonunion could be prevented for every fourteen patients treated with reamed IM nailing [number needed to treat (NNT) = 14.28]. The risk ratios for secondary outcome measures were: implant failure, 0.30 (95% CI, 0.16 to 0.58; p < 0.001); malunion, 1.06 (95% CI, 0.32 to 3.57); pulmonary embolus, 1.10 (95% CI, 0.26 to 4.76); compartment syndrome, 0.45 (95% CI, 0.13 to 1.56); and infection, 0.98 (95% CI, 0.21 to 4.76). Sensitivity analyses suggested that reported rates of nonunion and implant failure were higher in studies of lower quality. The type of long bone fractured (tibia or femur), the degree of soft tissue injury (open or closed), study quality, and whether a study was published or unpublished did not significantly alter the relative risk of nonunion between reamed and nonreamed IM nailing. CONCLUSIONS: There is evidence from a pooled analysis of randomized trials that reamed IM nailing of lower extremity long bone fractures significantly reduces rates of nonunion and implant failure in comparison with nonreamed nailing.

High and low pressure irrigation in contaminated wounds with exposed bone.

BACKGROUND: Irrigation and debridement are essential in the initial management of traumatic wounds. The relative efficicacy of low pressure irrigation compared with high pressure irrigation remains unclear. AIMS: The purpose of this study was to examine the time dependent efficacy of both high and low pressure lavage in removing adherent bacteria from traumatic wounds with exposed bone. METHODS: Using an in-vivo model, we created bilateral Staphylococcus aureus contaminated femoral wounds in 30 mice. The wounds were incubated for 1 to 10 hours and lavaged with either high (70 psi) or low pressure lavage (1-2 psi). The mean colony forming units of bacteria were compared between groups at each time point. RESULTS: High and low pressure lavage were effective in removing adherent bacteria from contaminated wounds up to 8 hours and 4 hours, respectively. High pressure lavage was more effective than low pressure at every time point. CONCLUSION: The efficacy of low pressure lavage in wounds with exposed bone is questionable when irrigation is delayed beyond 4 hours.

Early versus delayed operative management of closed tibial fractures.

Fractures of the tibial shaft are the most common long bone fractures. Operative treatment of isolated closed tibial shaft fractures frequently is delayed in favor of treatment of life threatening injuries. A retrospective chart review of 200 tibial fractures was performed. These injuries were managed by two surgeons at a Level 1 trauma center between 1989 and 1996. Strict inclusion criteria identified 54 patients with an isolated closed tibial fracture. Postoperative hospital stay and complication rates were recorded. At a mean followup of 3.6 years, a quality of life questionnaire was administered via telephone calls to these patients. Two patient groups were identified: Group 1, 21 patients (< 12-hour surgical delay); and Group 2, 33 patients (> 12-hour surgical delay). Both groups were similar for baseline characteristics. Group 2 patients remained an extra 4.6 days in the hospital. A Kaplan-Meier analysis revealed that by the eighth postoperative day, all Group 1 patients were discharged from the hospital, whereas 47.8% of Group 2 patients remained in the hospital. Plate fixation was associated with a greater incidence of complications when compared with intramedullary nail internal fixation. Complication rates were significantly greater in the delayed surgical group. A multiple regression analysis revealed that surgical delay and postoperative complications accounted for 35% of the total variance in postoperative hospital stay. Time to surgical treatment was not prognostic of long term quality of life. Surgical delay results in longer postoperative hospital stays, greater complication rates, and increased total cost to the health care system.

Organ injuries associated with femoral fractures: implications for severity of injury in motor vehicle collisions.

OBJECTIVE: To determine if motor vehicle collisions (MVCs) resulting in femoral fractures were associated with a different injury severity and pattern of injury compared with crashes in which victims did not sustain femoral fractures. METHODS: Retrospective review of seriously injured motor vehicle occupants admitted to a regional trauma unit (Hamilton General Hospital) during a 69-month period (April 1991 to December 1996) for whom detailed crash details were known. RESULTS: Data for 733 motor vehicle occupants with Injury Severity Scores greater than 12 were available; 112 occupants (15.3%) sustained femoral fractures, and 621 occupants (84.7%) did not sustain femoral fractures. Victims with femoral fractures had a significantly higher mean Injury Severity Score (29.4 compared with 25.3 for non-femoral fracture group; p<0.001). The femoral fracture group had a higher incidence of bowel (p<0.012) and hemopneumothorax (p<0.02) injuries as well as an increased incidence of upper and lower extremity (p<0.001) and pelvic (p<0.05) fractures. CONCLUSION: The presence of a femoral fracture is strongly associated with the pattern and severity of injuries sustained by occupants in MVCs. A high index of suspicion is warranted in identifying associated organ injuries in MVC victims with concomitant femoral fractures.

High and low pressure pulsatile lavage of contaminated tibial fractures: an in vitro study of bacterial adherence and bone damage.

OBJECTIVE: This study was designed to examine the effect of pulsatile irrigation on microscopic bone architecture and its time-dependent efficacy in removing adherent slime-producing bacteria from cortical bone. DESIGN: Using an in vitro model, ten-millimeter transverse cut sections from five human tibiae were contaminated with Staphylococcus aureus and subjected to either high pressure pulsatile lavage (HPPL; seventy pounds per square inch, normal saline) or low pressure pulsatile lavage (LPPL; fourteen pounds per square inch, normal saline) or served as controls. Alteration of bony architecture was quantified by using a previously described ordinal scale and histomorphometric analysis of each transverse cut section of tibia. To assess the time-dependent effectiveness of pulsatile lavage in removing adherent bacteria from bone, ten-millimeter transverse cut sections from ten canine tibiae were contaminated with S. aureus and subjected to high or low pressure pulsatile lavage immediately or after one, three, or six hours. Scanning electron microscopy and bacterial cultures were used to assess the removal of adherent bacteria. RESULTS: HPPL resulted in significantly greater macroscopic damage than was seen with LPPL or in controls (ANOVA, p < 0.001). Histomorphometry revealed that HPPL was associated with significantly larger and more numerous fissures or defects in the cortical bone when compared with low pressure irrigation (p < 0.001). However, high and low pressure lavage were associated with similar degrees of periosteal separation from the cortical bone surface (p = 0.87). Both high and low pressure lavage were effective in removing adherent bacteria from bone at three hours irrigation delay, but only high pressure lavage removed adherent bacteria from bone at six hours delay. CONCLUSION: In this in vitro study, compared with HPPL, LPPL led to less structural damage and was equally effective in removing bacteria within three hours debridement delay; however, the efficacy of LPPL at six hours debridement delay is questionable. This finding may have clinical significance in the development of infection following open tibial fractures.

High pressure pulsatile lavage of contaminated human tibiae: an in vitro study.

OBJECTIVE: This study was designed to examine the effect of high pressure pulsatile lavage (HPPL) on bone destruction and propagation of bacteria in experimentally contaminated human tibiae. METHODS: Using an in vitro model, nine human tibiae from above-knee amputations were tested. A mid-diaphyseal tibial shaft fracture was created, and each end of the fracture was contaminated with bacteria (six tibiae with Staphylococcus aureus, three tibiae with Escherichia coli). The proximal end was designated as the control and the distal end was the test site. The test site was debrided by HPPL (seventy pounds/square inch, 1,200 milliliters/minute, 1,050 cycles/minute) with three liters of normal saline, whereas the control site did not receive any form of irrigation. Serial sections at increasing distance from the fracture site were cultured and the numbers of bacterial colony-forming units (CFUs) were determined at each level. The degree of macroscopic architectural change in each serial section was graded on an ordinal scale. RESULTS: Analysis of culture data revealed a reproducible pattern of bacterial propagation into the intramedullary canal. Peak bacterial seeding occurred at two to three centimeters from the fracture site (p = 0.023, Wilcoxon signed rank test). The degree of bone destruction varied proportionally with the depth into the canal and was found to be predictive of the extent of bacterial propagation determined by culture data. CONCLUSION: In an in vitro model of a contaminated fracture, HPPL resulted in bacterial seeding into the intramedullary canal and significant damage to the architecture of the bone. These observations might have clinical significance.

Follow-up study of arthroscopic reduction and fixation of type III tibial-eminence fractures.

UNLABELLED: Nine children (average age, 13.1 years) with 10 displaced type III tibial-eminence fractures were reviewed with an average follow-up of 3.5 years. The fractures were treated with arthroscope-assisted reduction and suture fixation. Nine of the 10 knees demonstrated meniscal interposition at the fracture site that contributed to unsuccessful closed reduction. At follow-up, subjective knee function was excellent in all cases, and no clinical or objective evidence of knee laxity or instability was detected in any patient. All patients demonstrated full range of motion of the affected knee compared with the contralateral side. CLINICAL SIGNIFICANCE: Arthroscopic reduction and fixation allow early mobilization; assists in defining and treating associated knee pathology; assists in fracture reduction; and reduces the morbidity associated with arthrotomy.