GIANT CELL TUMOR OF BONE: A MULTICENTER EPIDEMIOLOGICAL STUDY IN BRAZIL

Introduction

Giant cell tumor of bone (GCTB) mainly affects young adults' long bone epiphyses, threatening bone strength and joint function. Surgery is the primary treatment, although post-surgery recurrence is significant. This study analyzes patient profiles, treatments, and outcomes for GCTB in Brazil.

Methods

We retrospectively assessed local recurrence, metastasis, and treatment approaches in 643 GCTB patients across 16 Brazilian centers (1989-2021), considering regional differences.

Results

5.1% (n=33) developed pulmonary metastases, 14.3% (n=92) had pathological fractures, and the local recurrence rate was 18.2% (n=114). Higher rates of pulmonary metastases (12.1%) and advanced tumors (Campanacci III, 88.9%) were noted in lower-income North and Northeast regions. The North also had more pathological fractures (33.3%), extensive resections (61.1%), and amputations (27.8%). These regions faced longer surgical delays (36-39 days) than the South and Southeast (27-33 days).

Conclusions

Our findings corroborate international data, underscoring regional disparities in Brazil that may lead to worse outcomes in disadvantaged areas. This highlights the need for improved orthopedic oncology care in Brazil's economically and structurally challenged regions. Level of Evidence III; Retrospective Cohort.

ROLE OF INCISIONAL VACUUM THERAPY IN ENDOPROSTHETIC BONE RECONSTRUCTION SURGERY

Reconstructive surgery with endoprostheses is the chosen method for treating bone malignancies. Postoperative infections are frequent complications, and their treatment involves prolonged hospital stays and antibiotic therapy. Among the advancements aimed at reducing the rate of postoperative infection, the use of incisional negative pressure therapy (iNPT) has shown promising results, with no reports in the literature regarding its use in patients with such conditions.

Objective

To evaluate the effectiveness of iNPT in reducing postoperative complications in surgeries for resection of bone tumors associated with modular endoprosthesis reconstruction.

Methods

Retrospective case series of 16 patients diagnosed with osteosarcoma, who underwent resection and reconstruction with endoprosthesis associated with iNPT during the postoperative period. Follow-up was performed for a period of six months, and the evaluated outcomes were the incidence of postoperative infection and complications of the surgical wound.

Results

The use of iNPT for a postoperative period of seven days resulted in only three (18.7%) cases of postoperative infection. No cases of wound dehiscence, seroma formation, or hematoma at the surgical site were observed.

Conclusion

The rate of surgical wound complications in our case series is lower than that reported in most of the literature, and iNPT appears to be an efficient way to reduce the rate of local complications in reconstructive surgeries with endoprosthesis after resection of bone malignancies. Level of Evidence III, Retrospective Study.

IMMUNOHISTOCHEMICAL ANALYSIS BY KI67 AND IDH1 IN PATIENTS WITH CHONDROSARCOMA

Objective

To perform an immunohistochemical evaluation using the IDH1 and Ki67 markers in patients who underwent treatment for chondrosarcoma in a reference service center in Brazil.

Methods

Retrospective analytical observational study using medical records of patients diagnosed with chondrosarcoma. Besides the epidemiological and clinical profile, important variables for prognosis and correlation with immunohistochemical analysis results with Ki67 and IDH1 markers were evaluated.

Results

Histopathological examinations by immunohistochemistry of 56 patients were analyzed, 52% of which were women, with the age group 20-60 years being more prevalent. Grade 1 and 2 histological subtypes corresponded to most chondrosarcomas. The femur, humerus, and tibia were the most frequent anatomical sites. Most tumors (59%) were larger than 8 cm. Ki67 expression was very low (< 10%) in 98% of patients. The analysis of IDH1 was positive in 43% of the cases. The correlation between IDH1 positivity and tumor size was statistically significant, but regarding survival, we observed no significance.

Conclusion

Immunohistochemical analysis using IDH1 and Ki67 markers in patients with conventional chondrosarcoma is not useful for prognostic guidance.Level of Evidence II, Prognostic Assessment, Results of Immunohistochemical Tests and Correlation with Survival.

Accuracy and safety of 3D printed surgical guides combined with monitored guidewires for placement of cervicothoracic pedicle screws: Technical note

Subaxial cervical pedicle screws provide rigid fixation, but their placement poses an important neurovascular injury risk. 3D printed guides have successfully been used to place pedicle screws, but experience in the subaxial cervical spine is limited. We present a case of cervicothoracic dissociation after a pathological fracture due to tumour involvement of the upper thoracic spine, causing paraparesis and intense pain. The cervicothoracic junction is of difficult visualization on fluoroscopy and the patients' severe instability made navigation unreliable. 3D printed individualized guidewire guides were used to help place canulated pedicle screws from C4 to T6. We successfully report the use of impedance guidewire monitoring to prevent pedicle violation and improve procedure safety.

UNDIFFERENTIATED PLEOMORPHIC SARCOMA: PROGNOSTIC FACTORS IN 42 EXTREMITY CASES

Introduction

Soft tissue undifferentiated pleomorphic sarcoma (UPS) in extremities is considered a rare neoplasm, corresponding to 5% of soft tissue sarcomas (STS) today. The objective was to evaluate prognostic factors related to death, local recurrence (LR), and impact on survival rates.

Methods

A retrospective study including 42 patients with UPS in extremities treated surgically in a single center. Comparisons were made between demographic data, characteristics of the neoplasia, and treatment. Between the variables with statistical significance, logistic regression analysis was used. Survival rates were evaluated using Kaplan-Meier plots. To compare the effect of variables on survival rates, the Log-Rank test was used.

Results

Age group of patients was from 25 to 85 years (mean 58 years), with a mean follow-up of 29.6 months. The variables with the highest effect on survival rates were sizes larger than 15 cm (T4) with p = 0.01, presence of metastatic lesions, and prognostic stage IV according to the American Joint Committee of Cancer (AJCC) with p < 0.001. The mean survival was 25.9 months. Metastasis and stage IV of AJCC were associated with a reduction in patient survival (17.8 months) with Log-Rank test p < 0.001. Conclusion: The main factors of poor prognosis related to mortality and reduction of survival of UPS in extremities were metastatic lesions and stage IV of AJCC. Level of Evidence III, Retrospective Study.

Comparison of Prophylactic Intravenous Antibiotic Regimens After Endoprosthetic Reconstruction for Lower Extremity Bone Tumors: A Randomized Clinical Trial

Question

Can a 5-day regimen of postoperative, prophylactic, intravenous antibiotics reduce the rate of surgical site infections in patients with a lower extremity bone tumor undergoing complex endoprosthetic reconstruction compared with a 1-day regimen?

Findings

In this randomized clinical trial including 604 patients in the primary analysis, the 5-day regimen did not reduce the rate of surgical site infection compared with the 1-day regimen, although it resulted in a higher rate of antibiotic-related complications, notably Clostridioides difficile–associated colitis.

Meaning

The results of this study suggest that prolonging use of postoperative antibiotics beyond 1 day does not reduce the rate of surgical site infection but increases the risk of clinically significant antibiotic-related complications.

Importance

The use of perioperative, prophylactic, intravenous antibiotics is standard practice to reduce the risk of surgical site infection after oncologic resection and complex endoprosthetic reconstruction for lower extremity bone tumors. However, evidence guiding the duration of prophylactic treatment remains limited.

Objective

To assess the effect of a 5-day regimen of postoperative, prophylactic, intravenous antibiotics compared with a 1-day regimen on the rate of surgical site infections within 1 year after surgery.

Design, Setting, and Participants

This randomized clinical superiority trial was performed at 48 clinical sites in 12 countries from January 1, 2013, to October 29, 2019. The trial included patients with a primary bone tumor or a soft tissue sarcoma that had invaded the femur or tibia or oligometastatic bone disease of the femur or tibia with expected survival of at least 1 year who required surgical management by excision and endoprosthetic reconstruction. A total of 611 patients were enrolled, and 7 were excluded for ineligibility.

Interventions

A 1- or 5-day regimen of postoperative prophylactic intravenous cephalosporin (cefazolin or cefuroxime) that began within 8 hours after skin closure and was administered every 8 hours thereafter. Those randomized to the 1-day regimen received identical saline doses every 8 hours for the remaining 4 days; patients, care providers, and outcomes assessors were blinded to treatment regimen.

Main Outcomes and Measures

The primary outcome in this superiority trial was a surgical site infection (superficial incisional, deep incisional, or organ space) classified according to the criteria established by the Centers for Disease Control and Prevention within 1 year after surgery. Secondary outcomes included antibiotic-related complications, unplanned additional operations, oncologic and functional outcomes, and mortality.

Results

Of the 604 patients included in the final analysis (mean [SD] age, 41.2 [21.9] years; 361 [59.8%] male; 114 [18.9%] Asian, 43 [7.1%] Black, 34 [5.6%] Hispanic, 15 [2.5%] Indigenous, 384 [63.8%] White, and 12 [2.0%] other), 293 were randomized to a 5-day regimen and 311 to a 1-day regimen. A surgical site infection occurred in 44 patients (15.0%) allocated to the 5-day regimen and in 52 patients (16.7%) allocated to the 1-day regimen (hazard ratio, 0.93; 95% CI, 0.62-1.40; P = .73). Antibiotic-related complications occurred in 15 patients (5.1%) in the 5-day regimen and in 5 patients (1.6%) allocated to the 1-day regimen (hazard ratio, 3.24; 95% CI, 1.17-8.98; P = .02). Other secondary outcomes did not differ significantly between treatment groups.

Conclusions and Relevance

This randomized clinical trial did not confirm the superiority of a 5-day regimen of postoperative intravenous antibiotics over a 1-day regimen in preventing surgical site infections after surgery for lower extremity bone tumors that required an endoprosthesis. The 5-day regimen group had significantly more antibiotic-related complications.

Trial Registration

ClinicalTrials.gov Identifier: NCT01479283

Extremities Soft Tissue Sarcomas, more Common and as Dangerous as Bone Sarcomas

Musculoskeletal sarcomas are rare diseases that require attention. They often present high degree of malignancy at diagnosis and, if underestimated, they can evolve aggressively locally and systemically. They present as soft tissue sarcoma and bone sarcomas, with soft tissue being four to five times more common. Most soft tissue sarcomas occur in the extremities. The most common subtypes in children and adolescents are rhabdomyosarcoma and synovial sarcoma; in adults, undifferentiated pleomorphic sarcoma, liposarcoma, leiomyosarcoma, myxofibrosarcoma and synovial sarcoma; all with a high degree of histological malignancy. Many soft tissue sarcomas are confused with benign soft tissue tumors, 100 times more common, so they are resected without the necessary planning, resulting in amputation of a limb that could have been preserved. As in all cancers, the most important prognostic factor is metastatic disease. When it is present, the overall survival rate falls around 20 to 30%. Survival rates are generally similar between bone and soft tissue sarcomas. So soft tissue sarcomas, in addition to being more prevalent, are as aggressive as bone sarcomas, deserving a lot of attention from orthopedic surgeons, who are often the first line of care of carriers of these tumors.

PRIMARY LEIOMYOSARCOMA OF BONE: CLINICOPATHOLOGIC AND PROGNOSTIC FACTORS ANALYSIS IN A SINGLE INSTITUTION

Objective

Primary leiomyosarcoma of bone (PLB) is a rare type of malignant bone tumor considered as a variant of the spindle cell sarcomas (SCS). The objective of this study was to analyze the clinicopathologic and the prognostic factors of patients with PLB treated at a single institution.

Methods

We retrospectively reviewed the records of 22 patients with pathologically confirmed PLB. The data collected were: age, sex, tumor size and location, grade and stage of the disease and histopathologic features. Mean age was 45.5 years (range, 17 to 73 y). Location was: upper limb (27.3%), lower limb (68.2%) and pelvis (4.5%). Patients had high grade in 90.9% of the reports. Margins were negative in 77.3% of the cases. Histological reports describe spindly sarcomatous cells arranged in fascicles with increased vascular formation without osteoid or chondroid matrix production. On immunohistochemistry, smooth muscle actin and desmin where positive in all cases.

Results

Mean follow-up time was 73.5 months (range, 5.3 to 331.1 m). We found 22.7% of local recurrence (LR). Distant metastasis (DM) was reported in 9 (40.9%) patients. Lung metastasis was the only DM affected site. Overall survival (OS) rate in 5 years was 59.1%. Predictors of OS were LR and DM.

Conclusions

PLB is an extremely rare malignant bone tumor that has a higher rate of DM and similar OS prognosis compared with other bone sarcomas. Level of Evidence IV, Case Series.

PROGNOSTIC FACTORS IN PATIENTS WITH APPENDICULAR MYXOFIBROSARCOMA

Objective

Myxofibrosarcoma (MFS) is a common soft tissue sarcoma (STS) that affects the extremities in elderly patients. The objective was to analyze the prognostic factors and outcomes of patients with MFS treated at a single institution.

Methods

We retrospectively reviewed the records of 75 patients with MFS. We compared age, sex, tumor size and location, grade and stage of the disease. Median age was 49.7 years (range, 1 to 88 y).

Location

upper extremity (25.4%), lower extremity (66.6%) and pelvis (8%). Patients had high-grade tumors in 46.7% of the reports. Margins were negative in 76% of the cases. Bivariate Cox regression analysis was used to determine associations between clinical and treatment factors with local recurrence (LR).

Results

Median follow-up time was 30.7 months (range, 1.8 to 383.8 m). We found 26.7% of LR. Distant metastasis (DM) was reported in 27 (36%) patients. Lung was the most common site of DM, reported in 92.6% of patients. Overall survival (OS) with metastasis was 21.2 months (range, 4.8 to 114.8 m). Predictors of OS were grade, LR (hazard ratio [HR] 5.13, 95% confidence interval, 2.15-12.24, P <0.001), and DM (HR 540.97, 95% confidence interval, 5.04-58112.03, P< 0.001).

Conclusions

Tumor grade, LR, positive margins and DM were significant predictors of poor OS prognosis. Level of Evidence IV, Case Series.

TIBIAL ADAMANTINOMA: ANALYSIS OF SEVEN CONSECUTIVE CASES IN A SINGLE INSTITUTION

Objective:

Adamantinoma accounts for less than 1% of the primary bone neoplasms. The tibia is the most affected bone and it is predominant in male patients between the second and third decades of life. The objective of this study is to obtain epidemiological and clinical information on patients with adamantinoma of the tibia treated surgically between 1989 and 2016.

Methods:

Retrospective series of seven patients diagnosed with adamantinoma of the tibia that underwent surgery at the orthopedic oncology service of our hospital. The information was obtained from the medical records and histopathological reports of our institution.

Results:

A total of 2870 medical records with histological reports were evaluated. Seven cases of adamantinoma of the tibia were included. The mean age was 28.5 (17-49) years. We found a predominance of females (71.4%) and the most affected side was the left one, with four cases (57.1%). The biopsy revealed bone adamantinoma in four (57.1%) patients, while the diagnosis of the other patients was confirmed after the histological examination of the surgical specimen. All the patients underwent surgery as definitive treatment. No positive margins were reported. No local recurrence (LR) was reported and two patients had distant metastasis (DM).

Conclusion:

The prognosis of survival in cases of adamantinoma of the tibia is high. The rates of LR and DM were low. Surgical treatment with extensive tumor resection is the treatment of choice. Level of Evidence IV, Case Series.

EXTRA-ABDOMINAL DESMOID TUMOR: ANALYSIS OF 23 CONSECUTIVE CASES IN A SINGLE INSTITUTION

OBJECTIVE

Extra-abdominal desmoid tumor (EDT) is a rare condition, caused by proliferation of fibroblasts. Despite being a benign tumor, it is locally aggressive and has unpredictable clinical behavior. The objective of this study is to present the clinical outcomes of patients with EDT treated surgically between 1995 and 2016.

METHODS

This is a retrospective series of 23 patients with histopathological diagnosis of EDT that underwent surgery at the orthopedic oncology service of our hospital. The information was obtained from the institute's clinical and pathology reports.

RESULTS

A total of 223 medical records with histopathological reports were evaluated. Only 23 cases of EDT were included in the present study. The mean age was 22.5 years. Twelve (52.2%) patients had the tumor on the lower limbs, seven (30.4%) on the upper limbs and four (17.4%) cases were reported on the back. Five (21.7%) patients had tumors measuring less than 5 cm, while eighteen (78.3%) patients had tumors measuring more than 5 cm. All patients underwent surgery as the definitive treatment in our institute. Twelve (52.2%) cases presented negative margins (NM) and eleven (47.8%) cases had positive margins (PM). Local recurrence (LR) occurred in eleven (47.8%) patients.

CONCLUSION

Impairment of the surgical margin was the only prognostic factor found for LR of EDT. Level of Evidence IV, Case Series.

SERUM VALUES OF ALKALINE PHOSPHATASE AND LACTATE DEHYDROGENASE IN EWING'S SARCOMA

OBJECTIVE

To study the relationship between the serum levels of alkaline phosphatase (AP) and lactate dehydrogenase (LDH), and the percentage of tumor necrosis (TN) in patients with Ewing´s Sarcoma (ES) .

METHODS

This is a case series with retrospective evaluation of patients with diagnosis of ES divided into 2 groups: Group 1, patients whose serum levels of alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) were obtained in the staging phase before preoperative chemotherapy (CT), and Group 2, patients whose values were measured after completion of the preoperative CT. The percentage of tumor necrosis (TN) of surgical specimens extracted in surgery was also evaluated .

RESULTS

Eighty four medical records from 1995 to 2015 were included. Both AP as LDH decreased in the patients studied, the pre CT value being higher than the post CT value. The average decrease of LHD was 272.95 U/L and AP was 10.17 U/L. The average tumor necrosis was 65.12 %. There was no statistical correlation between serums levels and the tumor necrosis percentage .

CONCLUSION

The serum levels values of AP and LDH are not predictors for chemotherapy-induced necrosis in patients with ES. Level of Evidence IV, Case Series.

UNCEMENTED ARTHROPLASTY AFTER HIP METASTATIC DISEASE AND MULTIPLE MYELOMA

Objective:

To describe a case series using a combination of narrative, graphical exploratory analysis and Bayesian Network modeling.

Methods:

Case series with 34 patients undergoing uncemented and hybrid arthroplasty procedures secondary to hip pain or fracture secondary to metastatic disease or multiple myeloma.

Results:

The most common tumors included gastrointestinal, multiple myeloma and breast cancer. Most devices were total arthroplasty (n = 16, 84.2%) rather than partial and uncemented arthroplasty (n = 12, 63.2%) rather than hybrid. The average time between surgery and deambulation was 20 days, the average length of hospital stay was 13 days, and the average patient survival was 589 days. Only one infection was reported. Uncemented and hybrid arthroplasty devices did not differ regarding time to walk, as well as the length of hospital stay in this sample.

Conclusion:

Our model may be used as a prior for the addition of subsequent patient samples, personalizing, thus, its recommendations to other patient populations. Level of Evidence IV, Case series.

Bioactive glass in cavitary bone defects: a comparative experimental study in rabbits

OBJECTIVES:

To compare bioactive glass and autograft regarding their histomorphometric characteristics.

METHODS:

The authors conducted a prospective case-control experimental study on animals in order to compare the histomorphometric characteristics of bioactive glass versus autograft. Eight rabbits underwent surgery in which a cavitary defect was created in both proximal femurs. One side was filled with bioactive glass granules and the other, with autograft grafted from the contralateral side. The sides were randomized. Fourteen days after surgery, the animals were euthanized.

RESULTS:

Histologic analysis revealed that bone neoformation was equivalent among the two groups and the osteoblasts cell-count was higher in the femurs treated with bioactive glass. The osteocytes cell-count, however, was lower. The similarity in bone formation between both groups was consistent to literature findings.

CONCLUSION:

Bioactive glass is similar to autograft regarding bone neoformation in this animal model of cavitary bone defects. Level of Evidence III, Case-Control Study.

GCT: What happened after 10 years of curettage and cement? Retrospective study of 46 cases

OBJECTIVE:

To compare the functional outcome of patients with and without arthrosis, and to determine whether the development of arthrosis is related to the distance of the tumor from the subchondral bone.

METHODS:

Forty six patients treated for Giant-cell tumor (GCT) between 1975 and 1999 met inclusion criteria. GCT was diagnosed by percutaneous biopsy and confirmed after resection, in all cases. Campanacci's and Kellgren's classification, the distance of the cement to the articular surface and MSTS score were obtained throughout the sample.

RESULTS:

The distance of the cement to the subchondral bone was associated with greater risk of developing arthrosis, but there was no difference in MSTS scores between patients with or without arthrosis.

CONCLUSION:

We found that the distance from the cement to the subchondral bone has a prognostic value regarding future arthrosis, but it does not impact on the functional outcome. Level of Evidence IV, Therapeutic Study

Correlation between the expression of vegf and survival in osteosarcoma

Objective:

To present a series of 50 consecutive patients with non-metastatic extremity osteosarcoma, and attempt to correlate expression of the vascular endothelial growth factor (VEGF) protein in biopsy tissue to their prognosis regarding overall survival, disease-free survival and local recurrence.

Methods:

Fifty cases of non-metastatic osteosarcoma of the extremities treated between 1986 and 2006 at Instituto de Ortopedia e Traumatologia da Universidade de São Paulo, São Paulo, Brasil, were evaluated regarding expression of the VEGF protein. There were 19 females and 31 males. The mean age was 16 years old (range 5-28 years old) and the mean follow-up was 60.6 months (range 25-167 months). The variables studied were age, gender, anatomic location, type of surgery, surgical margins, tumor size, post chemotherapy necrosis, local recurrence, pulmonary metastasis and death.

Results:

Thirty-six patients showed VEGF expression on 30% or less cells (low), and the remaining 14 cases had VEGF expression above 30% (high). Among the 36 patients with low VEGF expression, nine developed pulmonary metastasis and four died (11.1%). Among the 14 patients with high VEGF expression, six developed pulmonary metastasis and three died (21.4%).

Conclusion:

There was no statistically significant correlation between the expression of VEGF and any of the variables studied. Level of Evidence IV, Therapeutic Study.

Analysis of in situ manganese(II) oxidation in the Columbia River and offshore plume: linking Aurantimonas and the associated microbial community to an active biogeochemical cycle

The Columbia River is a major source of dissolved nutrients and trace metals for the west coast of North America. A large proportion of these nutrients are sourced from the Columbia River Estuary, where coastal and terrestrial waters mix and resuspend particulate matter within the water column. As estuarine water is discharged off the coast, it transports the particulate matter, dissolved nutrients and microorganisms forming nutrient-rich and metabolically dynamic plumes. In this study, bacterial manganese oxidation within the plume and estuary was investigated during spring and neap tides. The microbial community proteome was fractionated and assayed for Mn oxidation activity. Proteins from the outer membrane and the loosely bound outer membrane fractions were separated using size exclusion chromatography and Mn(II)-oxidizing eluates were analysed with tandem mass spectrometry to identify potential Mn oxidase protein targets. Multi-copper oxidase (MCO) and haem-peroxidase enzymes were identified in active fractions. T-RFLP profiles and cluster analysis indicates that organisms and bacterial communities capable of oxidizing Mn(II) can be sourced from the Columbia River estuary and nearshore coastal ocean. These organisms are producing up to 10 fM MnO₂ cell⁻¹ day⁻¹. Evidence for the presence of Mn(II)-oxidizing bacterial isolates from the genera Aurantimonas, Rhodobacter, Bacillus and Shewanella was found in T-RFLP profiles. Specific Q-PCR probes were designed to target potential homologues of the Aurantimonas manganese oxidizing peroxidase (Mop). By comparing total Mop homologues, Aurantimonas SSU rRNA and total bacterial SSU rRNA gene copies, it appears that Aurantimonas can only account for ~1.7% of the peroxidase genes quantified. Under the broad assumption that at least some of the peroxidase homologues quantified are involved in manganese oxidation, it is possible that other organisms oxidize manganese via peroxidases.

Chondrosarcoma of bone: lessons from 46 operated cases in a single institution

BACKGROUND

Bone chondrosarcomas are rare malignant tumors that have variable biologic behavior, and their treatment is controversial. For low-grade tumors, there is no consensus on whether intralesional en bloc resections are the best treatment.

QUESTIONS/PURPOSES

We therefore compared patients with Grade 1 and Grade 2 primary central chondrosarcomas to (1) determine difference in survival and (2) local recurrence rates; and (3) determine any association of histological grade with some clinical and demographic characteristics.

METHODS

We retrospectively reviewed 46 patients with grade 1 and 2 chondrosarcomas. There were 25 men and 21 women with a mean age of 43 years (range, 17-79 years). Minimum followup was 32 months (mean, 99 months; range, 32-312 months) for the patients who remained alive in the end of the study. Twenty-three of the tumors were intracompartmental (Enneking A); of these, 19 were Grade 1 and 4 were Grade 2. Twenty-three tumors were extracompartmental (Enneking B); of these, 4 were Grade 1 and 19 were Grade 2. Twenty-five patients underwent intralesional resection, 18 had wide resection, and three had amputations.

RESULTS

The overall survival rate was 94% and the disease-free survival rate was 90%. Among the 23 Grade 1 tumors, we observed six local recurrences and none of these patients died; among the 23 Grade 2 tumors, 10 recurred and two patients died. Local recurrence negatively influenced survival.

CONCLUSIONS

For lesions with radiographic characteristics of intracompartmental Grade 1 chondrosarcoma, we believe intralesional resection followed by electrocauterization and cement is the best treatment. When the imaging suggests aggressive (Grade 2 or 3) chondrosarcoma, then wide resection is promptly indicated.

Culturable Rhodobacter and Shewanella species are abundant in estuarine turbidity maxima of the Columbia River

Measurements of dissolved, ascorbate-reducible and total Mn by ICP-OES revealed significantly higher concentrations during estuarine turbidity maxima (ETM) events, compared with non-events in the Columbia River. Most probable number (MPN) counts of Mn-oxidizing or Mn-reducing heterotrophs were not statistically different from that of other heterotrophs (10³ -10⁴ cells ml⁻¹) when grown in defined media, but counts of Mn oxidizers were significantly lower in nutrient-rich medium (13 cells ml⁻¹). MPN counts of Mn oxidizers were also significantly lower on Mn(III)-pyrophosphate and glycerol (21 cells ml⁻¹). Large numbers of Rhodobacter spp. were cultured from dilutions of 10⁻² to 10⁻⁵, and many of these were capable of Mn(III) oxidation. Up to c. 30% of the colonies tested LBB positive, and all 77 of the successfully sequenced LBB positive colonies (of varying morphology) yielded sequences related to Rhodobacter spp. qPCR indicated that a cluster of Rhodobacter isolates and closely related strains (95-99% identity) represented approximately 1-3% of the total Bacteria, consistent with clone library results. Copy numbers of SSU rRNA genes for either Rhodobacter spp. or Bacteria were four to eightfold greater during ETM events compared with non-events. Strains of a Shewanella sp. were retrieved from the highest dilutions (10⁻⁵) of Mn reducers, and were also capable of Mn oxidation. The SSU rRNA gene sequences from these strains shared a high identity score (98%) with sequences obtained in clone libraries. Our results support previous findings that ETMs are zones with high microbial activity. Results indicated that Shewanella and Rhodobacter species were present in environmentally relevant concentrations, and further demonstrated that a large proportion of culturable bacteria, including Shewanella and Rhodobacter spp., were capable of Mn cycling in vitro.

Primary malignancy in giant cell tumor: a case report

CONTEXT

Primary malignancy in giant cell tumor (PMGCT) is rare. It is defined as a high-grade sarcoma originating in a giant cell tumor (GCT) and seems to behave less aggressively than its secondary counterpart does.

CASE REPORT

This report presents the case of a 39-year-old female with pain in her left shoulder for one month. Radiography showed a pathological fracture of the proximal humerus associated with an osteolytic lesion. Histopathological analysis showed typical areas of GCT juxtaposed with a sarcomatous component.

CONCLUSIONS

PMGCT seems to behave less aggressively than secondary malignancy in GCT, and it may simulate its more common benign counterpart clinically and radiographically. However, it requires a more aggressive type of treatment.

Estudo histopatológico do trajeto de biópsia de tumores musculoesqueléticos malignos

OBJETIVO: Verificar se havia risco de contaminação por células neoplásicas no trajeto da biópsia e estudar as alterações histológicas locais. MÉTODOS: Realizou-se um estudo prospectivo com trajetos de biópsias de pacientes operados por tumores musculoesqueléticos malignos no Instituto de Ortopedia e Traumatologia da Faculdade de Medicina da Universidade de São Paulo no período de abril de 2006 a abril de 2007. Foram estudados por histopatologia 25 casos. RESULTADOS: Houve implante de células neoplásicas em 32% dos trajetos. As alterações histológicas mais comuns nos casos positivos foram classificadas como: fibrose acentuada, componente inflamatório leve e neovascularização acentuada. CONCLUSÃO: Sugerimos a ressecção tradicional oncológica do trajeto junto com a peça.

Prognostic factors and expression of MDM2 in patients with primary extremity liposarcoma

OBJECTIVE

The objective of this study was to investigate MDM2 (murine double minute 2) protein expression and evaluate its relationship with some anatomical and pathological aspects, aiming also to identify prognostic factors concerning local recurrence-free survival, metastasis-free survival and overall survival in patients with primary liposarcomas of the extremities.

MATERIALS AND METHODS

Of 50 patients with primary liposarcomas of the extremities admitted to a Reference Service, between 1968 and 2004, 25 were enrolled in the study, following eligibility and exclusion criteria.

RESULTS

The adverse factors that influenced the risk for local recurrence in the univariant analysis included male sex (P = 0.023), pleomorphic histological subtype (P = 0.027), and high histological grade (P = 0.007). Concerning metastasis-free survival, age less than 50 years (P = 0.040), male sex (P = 0.040), pleomorphic subtype (P < 0.001), and high histological grade (P = 0.003) had a worse prognosis. Adverse factors for overall survival were age under 50 years (P = 0.040), male sex (P = 0.040), pleomorphic subtype (P < 0.001), and high histological grade (P = 0.003).

CONCLUSIONS

There was no correlation between immunohistochemically observed MDM2 protein expressions and the anatomical and pathological variables studied. The immunohistochemical expression of MDM2 protein was not considered to have a prognostic value for any of the surviving patients in this study (local recurrence-free survival, metastasis-free survival, or overall survival). The immunoexpression of MDM2 protein was a frequent event in the different subtypes of liposarcomas.

Synovial sarcoma of the extremities: prognostic factors for 20 nonmetastatic cases and a new histologic grading system with prognostic significance

PURPOSE

To evaluate 20 cases of nonmetastatic synovial sarcoma of the extremities regarding prognostic factors, and to propose a histologic grading system with prognostic significance.

METHODS

The cases of 20 patients (14 females and 6 males) with nonmetastatic synovial sarcomas of the extremities treated between 1985 and 1998, were retrospectively evaluated regarding prognostic factors. A histologic grading system with prognostic significance is proposed.

RESULTS

The mean follow-up period was 48.4 months (range, 16-116 months). There was local recurrence in 3 cases (15%), microscopic surgical margin being the only prognostic factor identified. Seven patients (35%) died of the disease in a mean postoperative period of 31.7 months (range, 16-53 months), all with pulmonary or brain metastasis. The survival rate was 65% in 48.4 months of follow-up.

CONCLUSION

The unfavorable prognostic factors identified regarding survival were high histologic grade, tumors proximal to the knee or elbow, and spontaneous tumor necrosis over 25%. Local recurrence did not have influence on survival in this study. The presence of mast cells appears to have a positive influence on survival, although statistical significance was not reached (P = 0.07). The oncologic and functional result was good in 6 cases (30%), regular in 7 (35%), and poor in 7 cases (35%).

Prognostic factors in pathologic fractures secondary to metastatic tumors

OBJECTIVE

Pathological fractures caused by metastases sharply decrease the quality of life and increase mortality rates for patients with malignant neoplasias. Orthopedic advances in osteosynthesis and endoprosthesis have been beneficial in the prevention and treatment of such fractures. The objective of our study was to determine which prognostic factors for pathologic fractures treated in our Service were significant.

METHOD

This was a retrospective study enrolling 112 patients treated for pathologic fractures secondary to metastatic tumors between April 1994 and December 2004 in our Service. Patients were analyzed according to sex, age, bone metastasis site, visceral metastases, origin of primary tumor, treatment type, serum hemoglobin, and survival.

RESULTS

The most affected site was the femur (44%), the most frequent primary tumor was breast cancer (25%); the most frequently employed surgical treatment was unconventional endoprosthesis (66%). Sex, age, primary tumor, site affected, non-bone metastasis, and clinical versus surgical treatment variables were not good predictors for survival. The only significant predictor was the type of surgery employed. Patients who received an endoprosthesis presented a worse prognosis (21.6 months) than patients undergoing osteosynthesis (47.8 months).

CONCLUSION

Patients undergoing osteosynthesis, with a less morbid surgical technique and earlier rehabilitation, had longer survival times than patients who received endoprostheses. Our case series is similar to international ones, where the most frequent primary tumor is breast tumor, followed by tumors of undetermined origin, prostate, and lung tumors.

Comparative analysis between osteosarcoma and Ewing's sarcoma: evaluation of the time from onset of signs and symptoms until diagnosis

OBJECTIVE

The purposes of this study were to describe the early signs and symptoms of osteosarcoma and Ewing's sarcoma, identify symptoms that could be used to help differentiate the two types of tumors, and determine the time elapsed between the onset of signs and symptoms and the definitive diagnosis in our service, providing information and imputus for earlier diagnosis of these tumors.

METHODS

A retrospective analysis of the medical dossiers of 365 patients under 30 years of age diagnosed with osteosarcoma or Ewing's sarcoma was performed, and the aspects of the clinical diagnosis were statistically analyzed and compared.

RESULTS

The time between the onset of signs and the symptoms was 5.25 months for osteosarcoma and 8.1 months for Ewing's sarcoma, and the most frequent (89.5%) early symptom of osteosarcoma and Ewing's sarcoma was local pain. Symptoms that might aid diagnosis included early local volume increase and the presence of fever.

CONCLUSION

The time until diagnosis of both neoplasias was higher than that reported for North America and Europe. Education of the lay public and medical professionals regarding suspicious early signs and symptoms might shorten the delay of diagnosis.

Oncologic progression of bone plasmacytomas to multiple myeloma

PURPOSE

To evaluate the clinical aspects, diagnoses, prognostic factors, and percent progression of plasmacytoma to multiple myeloma.

MATERIALS AND METHODS

103 medical records of patients suspected of plasmacytoma were surveyed covering the period between 1950 and 1998, and 30 were selected for analysis. Patients were classified into 2 groups: patients who did (n = 17) and did not (n = 13) progress to multiple myeloma. Comparative statistics regarding a variety of clinical aspects were developed.

RESULTS

Patients who progressed to multiple myeloma were younger than those who did not (52.3 +/- 2.6 vs 62.6 +/- 3.4 years; mean +/- SEM; P = 0.02). There were no significant differences in gender between groups. A higher incidence of multiple recurrence was observed in patients who progressed to multiple myeloma (75%, P = 0.049). Both groups showed a prevalence of vertebral column injuries. No significant differences were found between groups regarding the disease period (from the onset of symptoms until diagnosis) (P = 0.20) and survival (P = 0.34). The average time to progression from plasmacytoma to myeloma was 41 +/- 39 months (mean +/- SD), and the progression rate was 57%.

CONCLUSION

Patients who progressed to multiple myeloma were younger than those who did not. No significant differences were found between groups regarding sex, time from symptom onset to diagnosis, and survival time. In both groups, the most affected anatomic location was the vertebral column, and most affected sex was male. The average time to progression to multiple myeloma was 41 months. It was not possible to determine the factors that influenced the survival of patients with plasmacytoma or for those who progressed to multiple myeloma.

Functional and radiographic evaluation of 214 aggressive benign bone lesions treated with curettage, cauterization, and cementation: 24 years of follow-up

PURPOSE

Treatment with curettage, cauterization, and methylmethacrylate of aggressive benign bone lesions is a method now widely accepted in most orthopedic oncology centers. However, one of the controversies regarding this technique is the possible complications that may arise from the use of methylmethacrylate, which has caused some authors to remove it 2 years after the surgery and replace it with bone graft. The objective of this paper is to present a functional and radiographic evaluation of 214 patients presenting with aggressive benign bone lesions treated with curettage, cauterization, and methylmethacrylate from 1974 to 1998, with some of them having 24 years of follow-up. These patients were clinically and radiographically evaluated for the incidence of late osteoarthrosis, range of motion, and pain in the involved joint.

METHOD

This study comprised 214 patients, with an average follow-up duration of 10.6 years (range: 2 to 24 years. All cases involved aggressive benign lesions. The patients were evaluated according to the Musculoskeletal Tumor Society Score (MSTS) functional evaluation system, and the complications are described.

RESULTS

The MSTS functional evaluation was excellent in 166 cases (78%), good in 26 (12%), fair in 11 (5%), and poor in 11 (5%). The following complications were observed: late osteoarthrosis, 25 cases (12%); infection, 12 (6%); pathologic fracture, 11 (5%); and local recurrence, 19 (9%).

CONCLUSION

Based on clinical assessment, no significant deleterious effects directly related to the use of methylmethacrylate were observed. The functional evaluation performed in 1998 (up to 24 years of follow-up) did not show significant change when compared to the evaluation performed in 1985.

Relationship between surgical procedure and outcome for patients with grade I chondrosarcomas

PURPOSE

To evaluate the oncological outcome of patients with grade I chondrosarcomas according to the type of surgical treatment performed, since there is still controversy regarding the need for aggressive resections to reach a successful outcome.

MATERIALS AND METHODS

The records of 23 patients with grade I chondrosarcomas were reviewed. The mean age was 38.4 years, ranging from 11 to 70 years; 52% were men and 48% were women. The femur was the site of 13 tumors. The tumors were staged as IA (17, 74%) and IB (6, 26%). Regarding tumor location, 74% (17) were medullary, 22% (5) were peripheral, and 4% (1) was indeterminate. Tumor size ranged from 2 to 25 cm, mean 7.9 cm. Regarding the surgical procedure, 11 patients underwent intralesional resection, 9 patients underwent wide resection, and 3 underwent radical resection. The follow-up period ranged from 24 to 192 months.

RESULTS

None of the patients developed local recurrence or metastases; 7 patients had other general complications.

CONCLUSIONS

This data supports the use of less aggressive procedures for treatment of low-grade chondrosarcomas.

Parosteal osteosarcoma with myocardial metastasis 13 years after follow-up

PURPOSE

To report the case of a woman with a diagnosis of grade II (low grade) parosteal osteosarcoma with the occurrence of myocardial metastasis 13 years after resection, and to present a review of the existing literature on the subject.

METHODS

Description of the case and review of the literature.

CONCLUSION

The review leads to the conclusion that the occurrence of metastasis from parosteal osteosarcoma can occur in up to 38% of the cases, in spite of its relatively low aggressiveness. However, myocardial metastasis of a parosteal osteosarcoma is an event that was not found in the literature.

Primary bone lymphoma in 24 patients treated between 1955 and 1999

The authors present their experience in the treatment of 24 patients with primary bone lymphoma. Eighty-one patients treated between 1955 and 1999 were evaluated, and 57 were excluded because of misdiagnosis. The male to female ratio was 7:5 and the median age was 38.5 years (range, 18-69 years). Two patients had human immunodeficiency virus. Seventeen patients had intermediate-grade lymphomas (Working Formulation), nine patients had centroblastic subtype (Kiel), and 22 patients had B immunophenotype. Nine patients had combined treatment with chemotherapy and radiation therapy, and nine patients had chemotherapy alone. The mean followup was 13.2 years (range, 1.5-37.3 years). Three patients had surgery, two because of subtrochanteric fractures (one patient had closed reduction and internal fixation and the other patient had resection and endoprosthesis reconstruction). The third patient presented with myelocompression at the thoracic level, and he had decompression surgery. Only one patient had radiation therapy and two patients had no treatment. There have been no local recurrences in 17 patients (70.8%). Seven patients (29.2%) died with evidence of disease within a followup of 11 months. The results of the current study showed that patients with primary bone lymphoma have a good prognosis when they are treated with chemotherapy, regardless of whether radiation therapy was given. Surgery usually is appropriate for patients with fractures.

Conformational component in the coupled transfer of multiple electrons and protons in a monomeric tetraheme cytochrome

Cell metabolism relies on energy transduction usually performed by complex membrane-spanning proteins that couple different chemical processes, e.g. electron and proton transfer in proton-pumps. There is great interest in determining at the molecular level the structural details that control these energy transduction events, particularly those involving multiple electrons and protons, because tight control is required to avoid the production of dangerous reactive intermediates. Tetraheme cytochrome c(3) is a small soluble and monomeric protein that performs a central step in the bioenergetic metabolism of sulfate reducing bacteria, termed "proton-thrusting," linking the oxidation of molecular hydrogen with the reduction of sulfate. The mechano-chemical coupling involved in the transfer of multiple electrons and protons in cytochrome c(3) from Desulfovibrio desulfuricans ATCC 27774 is described using results derived from the microscopic thermodynamic characterization of the redox and acid-base centers involved, crystallographic studies in the oxidized and reduced states of the cytochrome, and theoretical studies of the redox and acid-base transitions. This proton-assisted two-electron step involves very small, localized structural changes that are sufficient to generate the complex network of functional cooperativities leading to energy transduction, while using molecular mechanisms distinct from those established for other Desulfovibrio sp. cytochromes from the same structural family.

Implicit solvation in the self-consistent mean field theory method: sidechain modelling and prediction of folding free energies of protein mutants

The Atomic Solvation Parameter (ASP) model is one of the simplest models of solvation, in which the solvation free energy of a molecule is proportional to the solvent accessible surface area (SAS) of its atoms. However, until now this model had not been incorporated into the Self-Consistent Mean Field Theory (SCMFT) method for modelling sidechain conformations in proteins. The reason for this is that SAS is a many-body quantity and, thus, it is not obvious how to define it within the Mean Field (MF) framework, where multiple copies of each sidechain exist simultaneously. Here, we present a method for incorporating an SAS-based potential, such as the ASP model, into SCMFT. The theory on which the method is based is exact within the MF framework, that is, it does not depend on a pairwise or any other approximation of SAS. Therefore, SAS can be calculated to arbitrary accuracy. The method is computationally very efficient: only 7.6% slower on average than the method without solvation. We applied the method to the prediction of sidechain conformation, using as a test set high-quality solution structures of 11 proteins. Solvation was found to substantially improve the prediction accuracy of well-defined surface sidechains. We also investigated whether the methodology can be applied to prediction of folding free energies of protein mutants, using a set of barnase mutants. For apolar mutants, the modest correlation observed between calculated and observed folding free energies without solvation improved substantially when solvation was included, allowing the prediction of trends in the folding free energies of this type of mutants. For polar mutants, correlation was not significant even with solvation. Several other factors also responsible for the correlation were identified and analysed. From this analysis, future directions for applying and improving the present methodology are discussed.

[Study of post-myocardial infarction ventricular aneurysms with equilibrium radionuclide angiography. Significance of Fourier analysis]

The concept of left ventricular aneurysm has been a subject of controversy and it's not yet completely settled. This has some implications on the patients selection for surgery and explains the various non-invasive methods so far developed for the clinical assessment of patients with ventricular aneurysms. Seventy-one patients with ischemic heart disease, 65 with recent myocardial infarction, were studied by equilibrium radionuclide angiography (ERNA) in order to define left ventricular wall motion abnormalities. One hundred ERNA were undertaken, through the usual erytrocites in vivo labelling technic, employing a GE 400 T Gama-Camera GP. Image acquisition was through 400 cardiac cycles, on LAO (30 and 60 degrees) and left lateral. PAGE protocol was employed. Fourier transform was used in the present work to obtain phase and amplitude images, which actually became the main criteria to define aneurysmatic areas. Global ejection fraction, regional wall motion and regional ejection fraction were other parameters investigated. Wall motion abnormalities have been identified in all the 65 patients having suffered a myocardial infarction. Extensive areas of akinesia or localized dyskinesia were present in 40 patients (16.5%), while remainder 25 had just localized hypoakinesia. Phase image enabled the selection of LV areas of contraction delay in 19 of the 40 patients with extensive wall motion abnormalities (Group I). In such Group I we could identify an LV area with contrasting colour, defining the aneurysmatic LV portion. In the order 21 patients with extensive akinesia, no significant changes of colour were present on ventricular phase image (Group II) meaning absence of aneurysm. No phase disturbances were seen in the remainder 25 patients with MI (Group III) and the 6 patients with CAD without MI had normal phase images (Group IV). The percentage of akinetic segments was 39.1 and 35.4 in Group I and II, respectively (p = .53) while it was significantly lower in Group III 17.9%; p < .0001). LV ejection fraction was statistically different in the four groups considered (I = 30.0% +/- 3.7; II = 39.9% +/- 2.9; III = 49.0% +/- 2.5; IV = 62.0% +/- 3.2). The degree of phase delay in aneurysmatic zones was quantified by the phase histogram. Average value of phase for the left ventricle was 129.7 +/- 8.4 degrees, and for the aneurysm it was 238.0 +/- 5.0 with an average phase delay of 104.8 +/- 4.1 degrees. The association of phase and amplitude images and the measurements of phase and amplitude values on the histograms allowed the distinction of akinetic aneurysm (phase delay and low amplitude) from the dyskinetic aneurysms (phase delay and high amplitude). Half of the isotopic diagnosis of aneurysms have been confirmed by classic contrast angiography, and a third of then have undergone surgery. The two dyskinetic aneurysms that have been submitted to aneurysmectomy had pos-operative improvement of LV function. On summary, phase and amplitude analysis by the Fourier method, which is independent of LV geometry, showed that LV regions with high phase values are associated with severe regional wall motion abnormalities and low ejections fractions. The definition of the sequence and amplitude of ventricular contraction allows the distinction of akinetic and dyskinetic aneurysms, anticipating the method as a valid contribution for the screening of patients likely to benefit from aneurysmectomy.

The use of a modular titanium endoprosthesis in skeletal reconstructions after bone tumor resections: method presentation and analysis of 37 cases

We analyzed 37 patients who underwent segmental wide resection of bone tumors and reconstruction with a modular titanium endoprosthesis at the Orthopaedic Oncology Group, between 1992 and 1998. Twelve patients were male and 25 were female, with a mean age of 30 years (9 - 81). The mean follow-up was 14 months (2 - 48). The diagnoses were: osteosarcoma (14 cases), metastatic carcinoma (10), Ewing's sarcoma (4), giant cell tumor (4), malignant fibrous histiocytoma (3), chondrosarcoma (1), and aneurysmal bone cyst (1). Eleven articulated total knee, 8 partial proximal femur with bipolar acetabulum, 8 partial proximal humerus, 3 total femur, 2 partial proximal tibia, 2 diaphyseal femur, 2 diaphyseal humerus, and 1 total proximal femur with cementless acetabulum endoprosthesis implant procedures were done. The complications related to the procedure included: infection (5 cases), dislocation (3), module loosening (1), and ulnar nerve paresthesia (1). We used the following criteria for the clinical evaluation: presence of pain, range of motion, reconstruction stability, surgical and oncologic complications, and patient acceptance. The results were good in 56.8% of the cases, regular in 32.4% and poor in 10.8%.

Improved modeling of side-chains in proteins with rotamer-based methods: a flexible rotamer model

Side-chain modeling has a widespread application in many current methods for protein tertiary structure determination, prediction, and design. Of the existing side-chain modeling methods, rotamer-based methods are the fastest and most efficient. Classically, a rotamer is conceived as a single, rigid conformation of an amino acid sidechain. Here, we present a flexible rotamer model in which a rotamer is a continuous ensemble of conformations that cluster around the classic rigid rotamer. We have developed a thermodynamically based method for calculating effective energies for the flexible rotamer. These energies have a one-to-one correspondence with the potential energies of the rigid rotamer. Therefore, the flexible rotamer model is completely general and may be used with any rotamer-based method in substitution of the rigid rotamer model. We have compared the performance of the flexible and rigid rotamer models with one side-chain modeling method in particular (the self-consistent mean field theory method) on a set of 20 high quality crystallographic protein structures. For the flexible rotamer model, we obtained average predictions of 85.8% for chi1, 76.5% for chi1+2 and 1.34 A for root-mean-square deviation (RMSD); the corresponding values for core residues were 93.0%, 87.7% and 0.70 A, respectively. These values represent improvements of 7.3% for chi1, 8.1% for chi1+2 and 0.23 A for RMSD over the predictions obtained with the rigid rotamer model under otherwise identical conditions; the corresponding improvements for core residues were 6.9%, 10.5% and 0.43 A, respectively. We found that the predictions obtained with the flexible rotamer model were also significantly better than those obtained for the same set of proteins with another state-of-the-art side-chain placement method in the literature, especially for core residues. The flexible rotamer model represents a considerable improvement over the classic rigid rotamer model. It can, therefore, be used with considerable advantage in all rotamer-based methods commonly applied to protein tertiary structure determination, prediction, and design and also in predictions of free energies in mutational studies.

Simulation of electron-proton coupling with a Monte Carlo method: application to cytochrome c3 using continuum electrostatics

A new method is presented for simulating the simultaneous binding equilibrium of electrons and protons on protein molecules, which makes it possible to study the full equilibrium thermodynamics of redox and protonation processes, including electron-proton coupling. The simulations using this method reflect directly the pH and electrostatic potential of the environment, thus providing a much closer and realistic connection with experimental parameters than do usual methods. By ignoring the full binding equilibrium, calculations usually overlook the twofold effect that binding fluctuations have on the behavior of redox proteins: first, they affect the energy of the system by creating partially occupied sites; second, they affect its entropy by introducing an additional empty/occupied site disorder (here named occupational entropy). The proposed method is applied to cytochrome c3 of Desulfovibrio vulgaris Hildenborough to study its redox properties and electron-proton coupling (redox-Bohr effect), using a continuum electrostatic method based on the linear Poisson-Boltzmann equation. Unlike previous studies using other methods, the full reduction order of the four hemes at physiological pH is successfully predicted. The sites more strongly involved in the redox-Bohr effect are identified by analysis of their titration curves/surfaces and the shifts of their midpoint redox potentials and pKa values. Site-site couplings are analyzed using statistical correlations, a method much more realistic than the usual analysis based on direct interactions. The site found to be more strongly involved in the redox-Bohr effect is propionate D of heme I, in agreement with previous studies; other likely candidates are His67, the N-terminus, and propionate D of heme IV. Even though the present study is limited to equilibrium conditions, the possible role of binding fluctuations in the concerted transfer of protons and electrons under nonequilibrium conditions is also discussed. The occupational entropy contributions to midpoint redox potentials and pKa values are computed and shown to be significant.

Comparative redox and pKa calculations on cytochrome c3 from several Desulfovibrio species using continuum electrostatic methods

A comparative study of the pH-dependent redox mechanisms of several members of the cytochrome c3 family has been carried out. In a previous work, the molecular determinants of this dependency (the so-called redox-Bohr effect) were investigated for one species using continuum electrostatic methods to find groups with a titrating range and strength of interaction compatible with a mediating role in the redox-Bohr effect. Here we clarify these aspects in the light of new and improved pKa calculations, our findings supporting the hypothesis of propionate D from heme I being the main effector in the pH-dependent modulation of the cytochrome c3 redox potentials in all the c3 molecules studied here. However, the weaker (but significant) role of other titrating groups cannot be excluded, their importance and identity changing with the particular molecule under study. We also calculate the relative redox potentials of the four heme centers among the selected members of the c3 family, using a continuum electrostatic method that takes into account both solvation and interaction effects. Comparison of the calculated values with available data for the microscopic redox potentials was undertaken, the quality of the agreement being dependent upon the choice of the dielectric constant for the protein interior. We find that high dielectric constants give best correlations, while low values result in better magnitudes for the calculated potentials. The possibility that the crystallographic calcium ion in c3 from Desulfovibrio gigas may be present in the solution structure was tested, and found to be likely.

The origin of trypsin: evidence for multiple gene duplications in trypsins

The trypsin family of serine proteases is one of the most studied protein families, with a wealth of amino acid sequence information available in public databases. Since trypsin-like enzymes are widely distributed in living organisms in nature, likely evolutionary scenarios have been proposed. A novel methodology for Fourier transformation of biological sequences (FOTOBIS) is presented. The methodology is well suited for the identification of the size and extent of short repeats in protein sequences. In the present paper the trypsin family of enzymes is analyzed with FOTOBIS and strong evidence for tandem gene duplication is found. A likely evolutionary path for the development of present-day trypsins involved an intrinsic extensive tandem gene duplication of a small DNA fragment of 15-18 nucleotides, corresponding to five or six amino acids. This ancestral trypsin gene was subsequently duplicated, leading to the earliest version of a full-sized trypsin, from which the contemporary trypsins have developed.

Evaluating isovelocity surface area flow convergence method with finite element modeling

Through numerical experimentation we investigated the isovelocity surface area flow convergence method used in estimating regurgitant valve flow rates. Recent advances in three-dimensional color Doppler flow imaging have created renewed interest in this method. Experimentation was based on the use of depth-averaged finite element models of the left heart. The heart models studied varied from "synthetic" representations to a model of a left heart traced from an actual echocardiographic image of a patient with a prolapsed mitral valve. The isovelocity surface area flow convergence method overestimated regurgitant flow rates throughout the Nyquist limits considered with a critical Nyquist limit in which this overestimation is minimized. The angle dependence of Doppler color flow imaging partially corrects for this overestimation. The isovelocity surface area flow convergence method is a viable alternative to methods currently in use. Through numerical experimentation, we have begun to shed light on the inaccuracies inherent in this flow convergence method.

[Ankle arthrodesis: critical analysis of three techniques]

The authors analyze the randomized use of three ankle arthrodesis techniques. Indications for this procedure, which are pain, instability, deformity and articular degeneration, are common to the three groups. In group I the Gatellier-Adams technique was used by transfibular approach. In group II the Kenneth-Johnson technique was adopted, using Calandruccio external fixator. The same surgical procedure was adopted in group III, using crossed canulated screws as fixation device. The specific advantages and disadvantages of each method are discussed. The criteria for evaluation of the results are the final roentgenographic position of the foot and the achievement of union. The critical analysis conclude that the major indications for group I technique are cases of "in situ" arthrodesis, for group II infected cases and for group III cases with severe malalignment.

Simulation of protein conformational freedom as a function of pH: constant-pH molecular dynamics using implicit titration

Solution pH is a determinant parameter on protein function and stability, and its inclusion in molecular dynamics simulations is attractive for studies at the molecular level. Current molecular dynamics simulations can consider pH only in a very limited way, through a somewhat arbitrary choice of a set of fixed charges on the titrable sites. Conversely, continuum electrostatic methods that explicitly treat pH effects assume a single protein conformation whose choice is not clearly defined. In this paper we describe a general method that combines both titration and conformational freedom. The method is based on a potential of mean force for implicit titration and combines both usual molecular dynamics and pH-dependent calculations based on continuum methods. A simple implementation of the method, using a mean field approximation, is presented and applied to the bovine pancreatic trypsin inhibitor. We believe that this constant-pH molecular dynamics method, by correctly sampling both charges and conformation, can become a valuable help in the understanding of the dependence of protein function and stability on pH.

A study of the contribution of changes in the cerebral blood volume to the haemodynamic response to anoxia in rat brain

A susceptibility contrast agent which does not pass into the extra-cellular space was used to study the effect of changes in the relative cerebral blood volume (CBV) on the haemodynamic response to anoxia, for both normal and ischaemic brain tissue, in a rat model of acute focal ischaemia. In non-ischaemic tissue a strong CBV component was observed in the haemodynamic response, both during and after anoxia. During anoxia the change in the CBV of the non-ischaemic tissue was estimated to be 40% in the caudate putamen and 70% in the frontal-parietal cortex. For severely ischaemic tissue (ischaemic caudate putamen) there was no change in the CBV during anoxia while in areas of moderate ischaemia (ischaemic frontal parietal cortex) a change of 20% was observed. The effect of the contrast agent on spin-echo images was consistent with a small reduction in the microvascular blood volume of the ischaemic tissue.

A study of the contribution of changes in the cerebral blood volume to the haemodynamic response to anoxia in rat brain

A susceptibility contrast agent which does not pass into the extra-cellular space was used to study the effect of changes in the relative cerebral blood volume (CBV) on the haemodynamic response to anoxia, for both normal and ischaemic brain tissue, in a rat model of acute focal ischaemia. In non-ischaemic tissue a strong CBV component was observed in the haemodynamic response, both during and after anoxia. During anoxia the change in the CBV of the non-ischaemic tissue was estimated to be 40% in the caudate putamen and 70% in the frontal-parietal cortex. For severely ischaemic tissue (ischaemic caudate putamen) there was no change in the CBV during anoxia while in areas of moderate ischaemia (ischaemic frontal parietal cortex) a change of 20% was observed. The effect of the contrast agent on spin-echo images was consistent with a small reduction in the microvascular blood volume of the ischaemic tissue.

Quantification of mitral flow by Doppler color flow mapping

This study was performed to develop and validate Doppler color flow methods for quantifying forward transmitral flow rates and volumes with isovelocity aliasing contours. We undertook computer modeling of flows and studied an animal model with strictly controlled mitral flows. Finite element analysis was first used to establish the isovelocity surface contours reconstructed from the magnitudes and directions of the velocity vectors proximal to the normal mitral orifice. We modeled finite element-simulated Doppler color flow isovelocity surfaces and computed non-angle-dependent simulated isovelocities to compare them. Then 24 pharmacologically induced hemodynamic states in six sheep in which mitral regurgitation had been previously created surgically were studied. Three methods were used for peak flow (PF) computation: (1) the classic hemispheric methods: PF = 2 pi r2.aliasing velocity; (2) a modified hemispheric method: PF = 2 pi r2.aliasing velocity Vo/Vo-aliasing velocity; and (3) a new segment of sphere method: PF = pi p2.aliasing velocity, where p is the chord from the zenith of the first aliasing contour to the circumference at its base. Mean volume flow was also calculated in combination with phasic flow information from continuous-wave Doppler echocardiography: mean volume flow = PF.VTI/Vmax.heart rate, where VTI and Vmax are the velocity-time integral and maximal velocity of mitral inflow by continuous-wave Doppler echocardiography. Compared with the flow rates obtained by electromagnetic flowmeters, different correlations and agreements were achieved for these methods. Correlation (r = 0.86) and agreement were best for the segment of sphere method for computation of forward mean volume flows in our model. Color flow Doppler quantitation with a segment of sphere or modified hemispheric method appears applicable for quantification of forward transmitral valve flow rates and volumes with reasonable accuracy.

Cerebrovascular changes in rats during ischemia and reperfusion: a comparison of BOLD and first pass bolus tracking techniques

Both first pass bolus tracking of a susceptibility contrast agent and blood oxygenation level dependent (BOLD) sequences provide information on the tissue perfusion and the cerebral blood volume, but each sequence has its own particular limitations. In this article, both techniques were used to assess the cerebrovascular changes occurring in a rat model of focal cerebral ischemia with reperfusion after 2 h of ischemia. The blood oxygenation level dependent studies were performed before, during, and after 60 s of anoxia to observe the response of the tissue to a respiratory challenge. Both techniques were able to detect ischemia and reperfusion; however, first pass bolus tracking provided better sensitivity and was easier to interpret. Because the blood oxygenation level dependent sequence did not provide any additional information, bolus tracking would appear to be the method of choice for studies of cerebral ischemia with reperfusion.

[Renal artery angioplasty]

In the 59 hypertensive patients submitted to percutaneous transluminal angioplasty (PTA) of the renal artery, there was an immediate success in the blood pressure in 91.5% and a later one of 79.6%. In these patients we obtained better results: 81.4% in the unilateral lesions, more than in the bilateral ones--72.7%; 82.5% in the renal artery trunk lesions, more than in the ostium ones--71.4%; 88.9% in the lesions of fibromuscular origin, more than in the aterosclerotic ones--75%; 84.4% in up to 55 years old patients, more than in older ones--71.4%. These differences were not significant. The results of renal angioplasty in renovascular hypertension suggest this type of intervention as an alternative treatment.