Outcomes of posterior cruciate ligament tibial avulsion treated with staple fixation: stress TELOS X-ray evaluation.

PURPOSE: Tibial-side avulsion injuries of the posterior cruciate ligament are rare injuries. In displaced fracture, the reduction and fixation is the treatment of choice, although the optimal surgical management has not yet been determined. The aim of this study was to evaluate the clinical, functional, and radiological outcome after an open reduction and internal fixation with staples of a posterior cruciate ligament tibial avulsion. METHODS: A historical cohort of patients who underwent open reduction and internal fixation with staple due to a posterior cruciate ligament tibial avulsion were reviewed. Minimum follow-up was 2 years. Demographic, clinical, and radiological data, including stress X-ray, were analyzed. Also, International Knee Documentation Committee Score, Tegner Knee Score, Lysholm Knee Score, Short-Form Health Survey, and four-point Likert scale were evaluated. RESULTS: Four males (57%) and 3 females (43%) were included in the final analysis. The mean age was 39 years (range 27-54). All patients had a fracture union. No implant migration was observed. Postoperative posterior drawer, reverse pivot shift, and varus/valgus stress were negative. In stress TELOS X-ray, no statistically significant differences were observed between the postoperative and contralateral knee. All evaluated scores had good or excellent results. CONCLUSIONS: Our study provides further evidence that the use of an open reduction and internal fixation with a staple could be a simple and reliable management for posterior cruciate ligament avulsion fractures of the tibia. In our study, the postoperative stress TELOS X-ray analyze showed a correct fixation and biomechanical function of the posterior cruciate ligament.

Simultaneous bilateral atypical femoral fracture in a patient receiving denosumab: case report and literature review.

Osteoporosis remains a chronic and common disease associated with high medical costs. Pharmacological therapy has shown to be a good strategy to significantly reduce fracture risk. While literary evidence for bone protection in the short and medium term is strongly in it's favor, there are concerns about long-term treatment with antiresorptive drugs. Increased risk of atypical femoral fractures (AFFs) have been demonstrated in several studies following the long-term use of bisphosphonate. Denosumab offers an alternative approach to the treatment of osteoporosis, however, it is also an antiresorptive drug. We present a case of simultaneous bilateral atypical femoral fractures in a patient with denosumab treatment. These findings highlight the need to reevaluate the optimal antiresorptive therapy duration, as well as the safety of transition from bisphosphonates to denosumab and the need for continued monitoring in the prevention of AFFs.

Time dedicated to physical activity among medical residents: are there differences based on gender or specialty type?

INTRODUCTION: Physical activity (PA) is associated with positive health outcomes such as prevention of chronic diseases, psychological well-being and improved work performance. Medical residents are subjected to sleep deprivation, extended work schedule and high burnout prevalence. These conditions may lead to the neglect of personal health and the restriction of time dedicated to PA. The objective of the present study was to analyze the time dedicated to PA of medical residents, comparing women vs men residents and surgical vs clinical residents. METHODS: It is a cross-sectional study performed in a Spanish third-level university hospital. All medical residents from our institution were invited to voluntarily participate in the study answering a web-based questionnaire on June 2022. Data regarding demographics, residency and PA practice was recorded. RESULTS: The response rate was 20.73% (114/550). The 32.5% of the residents considered themselves to be physically inactive and mean time dedicated to PA in a regular week was 3.62 ±â€¯2.22 h. Men residents dedicated more time to PA than women residents (4.23 ±â€¯2.42 h vs 3.14 ±â€¯1.95 h, p = 0.012) and surgical residents dedicated more time than clinical residents (4.33 ±â€¯2.36 h vs 3.23 ±â€¯2.05 h, p = 0.01). CONCLUSIONS: One third of the medical residents consider themself physically inactive. Women and clinical residents practice PA less time than men and surgical residents. Efforts should be made to encourage PA among residents, especially in women and non-surgeons.

Ultrasound-guided genicular nerve block for pain control after total knee replacement: Preliminary case series and technical note. / Bloqueo ecoguiado de los nervios geniculados en el manejo analgésico de la artroplastia de rodilla: descripción de la técnica y resultados clínicos preliminares.

INTRODUCTION: Total knee arthroplasty (TKA) is an operation with moderate to severe postoperative pain. The Fast-Track models employ local infiltration techniques with anaesthetics at high volumes (100-150ml). We proposed a genicular nerve block with low volume of local anaesthetic. The aim of our study is to evaluate the periarticular distribution of these blocks in a fresh cadaver model and to describe the technique in a preliminary group of patients submitted to TKA. MATERIALS AND METHODS: In the anatomical phase, 4 genicular nerves (superior medial, superior lateral, inferior medial and inferior lateral) were blocked with 4ml of local anaesthetic with iodinated contrast and methylene blue in each (16ml in total). It was performed on a fresh cadaver and the distribution of the injected medium was evaluated by means of a CT-scan and coronal anatomical sections on both knees. The clinical phase included 12 patients scheduled for TKA. Ultrasound-guided block of the 4 genicular nerves was performed preoperatively and their clinical efficacy evaluated by assessing pain after the reversal of the spinal block and at 12h after the block. Pain was measured using the numerical scale and the need for rescue analgesia was evaluated. RESULTS: A wide periarticular distribution of contrast was observed by CT-scan, which was later evaluated in the coronal sections. The distribution followed the joint capsule without entering the joint, both in the femur and in the tibia. The pain after the reversal of the subarachnoid block was 2±1, requiring rescue analgesia in 42% of the patients. At 12h, the pain according to the numerical scale was 4±1, 33% required rescue analgesia. CONCLUSION: The administration of 4ml of local anaesthetic at the level of the 4 genicular nerves of the knee produces a wide periarticular distribution. Our preliminary data in a series of 12 patients undergoing TKA seems to be clinically effective. Nevertheless, extensive case series and comparative studies with local infiltration techniques with anaesthetics are needed to support these encouraging results.

Variation of activity of protein kinases in unstimulated and phytohemagglutinin-stimulated normal and leukemic human lymphocytes.

Cyclic adenosine 3':5'-monophosphate-dependent protein kinase (kinase A) and cyclic guanosine 3':5'-monophosphate-dependent protein kinase (kinase G) were assayed in lymphocytes of normal subjects, adults with chronic lymphocytic leukemia (CLL), and children with acute lymphocytic leukemia (ALL). There was a good correlation between the activity of the two kinases and the level of the corresponding cyclic nucleotides. This was true for cultured phytohemagglutinin-stimulated normal lymphocytes and CLL lymphocytes as well. Kinase A activity was low and kinase G activity was high in leukemic cells in the absence of the respective cyclic nucleotides [5 and 8 units (pmol 32P incorporated into histone per min per mg protein) for kinase A and 98 and 51 units for kinase G in ALL and CLL lymphocytes, respectively]. Upon addition of cyclic adenosine 3':5'-monophosphate and cyclic guanosine 3':5'-monophosphate in vitro, values for kinase A activity returned to normal (approximately 30 units), whereas those for kinase G increased further (212 units for ALL and 85 units for CLL lymphocytes; 22 units was the kinase activity for normal lymphocytes). These findings suggest that cyclic nucleotides achieve thetr specificity in the regulation of the cell, in part, through the activation of the dependent protein kinases and that both kinase A and kinase G may be functionally intact in leukemic cells.

Adhesive interaction of hemopoietic progenitor cell membrane with the RGD domain of fibronectin.

The binding of two cloned hemopoietic progenitor cell lines, B6Sut (multipotential) and FDCP-1 (bipotential) to dishes coated with fibronectin or its chymotryptic fragments was studied by labeling the cells with 51Cr or [35S]methionine. Intact fibronectin molecule and its 120 kDa fragment, containing the Arg-Gly-Asp (RGD) sequence motif, as well as a synthetic RGD-containing peptide Peptite 2000 all bound progenitor cells. However, the 40 or 45 kDa fragments, containing the heparin-binding and CS-1 domains, failed to bind the cells in a comparable magnitude. The binding of intact fibronectin and its 120 kDa fragment was inhibited in a dose-dependent fashion with increasing concentration of RGD-containing Gly-Arg-Gly-Asp-Ser peptide, but not with Gly-Arg-Gly-Glu-Ser control peptide that does not contain the RGD sequence motif. To explore the nature of the receptor for this fragment of fibronectin, membrane proteins were labeled with 125I and subjected to affinity chromatography using a matrix to which the 120 kDa fragment of fibronectin was covalently bound. Specific competitive elution with RGD yielded two bands with molecular masses of 160 and 110 kDa, corresponding, respectively, to those of alpha 5 and beta 1 chains of integrin molecule. Western blotting of whole-cell-lysate proteins with a monospecific, polyclonal serum specific for vertebrate beta 1 integrins identified a beta 1 integrin in these cells. Thus, it appears that an interaction involving alpha 5 beta 1 integrin with 120 kDa fragment of fibronectin may be involved between hemopoietic progenitor cells and the fibronectin component of extracellular matrix.

Expression of chondroitin sulfate as a unique type of proteoglycan on the cell membrane of multipotential and committed hemopoietic progenitor cells.

Proteoglycans are increasingly implicated as a major factor in the regulation of hemopoiesis. They are generally synthesized by stromal cells and released to the extracellular matrix. More recently the ability of hemopoietic progenitor cells to synthesize proteoglycans has come into focus. In the present study we maintained 3 cloned factor-dependent hemopoietic progenitor cells (B6 and F-mix which are multipotential and F-2 which is bipotential) in liquid culture. The cells were pulse-labeled with 35SO4 which becomes incorporated into the glycan side-chains of proteoglycans. We then studied subcellular distribution and chemical characterization of the newly synthesized proteoglycans. All 3 cell lines synthesized chondroitin sulfate as a unique type of proteoglycan as identified by gel filtration on a Sepharose CL-4B column followed by chondroitinase ABC cleavage of its glycosaminoglycan. This single type of proteoglycan was compartmentalized into intracellular, membrane-associated and extracellular pools. Its density on the membrane appeared to be a function of the differentiation state of the cell. The functional significance of membrane-associated proteoglycan in hemopoietic progenitor cells appears to be underestimated and requires further investigation.

Triglyceride synthesis by human bone marrow fibroblasts.

An increase in triglyceride synthesis has been observed in cultures of human bone marrow fibroblasts after the cells reach confluence. The addition of hydrocortisone further enhances triglyceride synthesis. Conditioned medium from confluent cultures also stimulates adipogenesis, probably mediated by a factor released through a hydrocortisone-dependent process. Subcultures derived from confluent cultures grown in the presence of hydrocortisone show a decrease in replicative capacity, as measured by DNA synthesis. This effect may represent the onset of a more differentiated phenotype, which seems to correspond to a cell showing a buoyant density of 1.052 g/ml and a high rate of triglyceride synthesis.

Adenoviral-mediated gene transfer into ex vivo expanded human bone marrow mesenchymal progenitor cells.

OBJECTIVE: Based on their differentiation properties and facilely of ex vivo expansion, human bone marrow mesenchymal progenitor cells (MPC), are considered as attractive targets to deliver foreign genes to the bone marrow or other mesenchymal tissues. In this study we investigated the feasibility of transduce MPC with adenoviral vectors (Adv). METHODS: MPC were expanded ex vivo and transduced with replication-defective Adv-containing reporter genes (lacZ or GFP) under the control of CMV promoter. Transfection efficiency was assessed by microscopical scoring or by flow cytometry. Expression and involvement of Adv-attachment (CAR) and Adv-internalization (integrins alphav) receptors were evaluated by flow cytometric studies. RESULTS: Transgene expression analysis showed that only 19%+/-3% of cells expressed the transgenes at high levels. MPC express the attachment and internalization receptors required for Adv infection. While integrins alphavbeta3 and alphavbeta5 are expressed by all MPC, CAR is solely expressed by a fraction of low size cells. Antibodies against CAR and alphavbeta5, but not against alphavbeta3, blocked Adv-mediated gene transfer into MPC, showing that CAR and alphavbeta5 are required for infection. Because alphavbeta5, as compared with CAR, is overexpressed in MPC, the results suggest that the efficiency of Adv-mediated gene transfer into MPC depends on the level of CAR expression. CONCLUSION: These findings demonstrate that Adv may be useful to engineer a subpopulation of ex vivo expanded human mesenchymal progenitors, with a high level of transgene expression.

Growth pattern and function of bone marrow fibroblasts from normal and acute lymphoblastic leukemia patients.

Studies were conducted on cultures of adherent cells derived from bone marrow of normal (N-BMF) and ALL (ALL-BMF) children. Quiescent cultures of both types of cells are differentially stimulated to synthesize DNA by serum. A 31-fold increase was observed in N-BMF, while in ALL-BMF, serum stimulates DNA synthesis only up to 7 times. Hydrocortisone (10(-8) M) inhibited up to 50% the effect of serum on DNA synthesis in N-BMF and had no effect in ALL-BMF. Glucocorticoid receptors, already described in N-BMF, are either absent or present in low amounts in ALL-BMF. These results indicate that stromal cells from normal and ALL bone marrow differ both in growth pattern and function.

A cytoadhesion assay for the binding of cloned hemopoietic progenitor cells to stroma.

Cell adhesion molecules responsible for the specific recognition and adhesion that necessarily occur between hemopoietic progenitor cells (HPC) and stromal cells within the bone marrow are likely of multiple nature in the cell membrane. Systems less complex than intact bone marrow, in which the interactions between adhesion molecules and their ligands may be studied, is greatly needed. Using 4 cloned murine IL-3-dependent HPC lines, B6Sut, FDCP-1, FDCP-2 and FDCP-Mix, a system of co-culture has been established and standardized with 2 murine stromal cell lines, GB1/6 and 3T3. HPC were radiolabeled with 51Cr, and an optimal set of conditions was established for the adherence of HPC to stromal cells. It was found that a source of IL-3, whether supplied as recombinant murine IL-3 or WEHI-conditioned medium, was a necessary component of the labeling and assay medium to achieve maximal adherence to stroma. Likewise, the presence of serum also resulted in overall better cytoadhesion than did serum-free conditions. All 4 cell lines bound GB1/6 in a reproducible manner from approximately 63% for FDCP-1 to 20% for FDCP-Mix; binding to 3T3 was higher than to GB1/6 for all HPC. Approximately 25 to 30% of the cell populations were not able to adhere to stroma, indicating a fairly constant degree of heterogeneity with respect to expression of adhesion molecules. Cytoadhesion was found to have at least one component that was temperature-sensitive, as adhesion of FDCP-1 to GB1/6 was 41.5 +/- 1.3% at 4 degrees C compared with 63.2 +/- 1.1% at 37 degrees C. The adhesion reaction itself occurred independently of metabolic energy production and relied on the presence of receptor-ligand molecules. This very standard and reproducible system should allow closer examination of the individual cytoadhesive events that occur between HPC and marrow stromal cells using cloned cell lines.

Restorative effect of IL-3 on adherence of cloned hemopoietic progenitor cell to stromal cell.

Mammalian hemopoiesis results from a complex interaction between hemopoietic progenitor cells, stromal cells and extracellular matrix components, orchestrated by specific glycoprotein growth factors. Recently, these growth factors have been shown to possess an important function, apart from stimulation of proliferation, and that is suppression of an active cellular process of programmed cell death, or apoptosis. Highly specific biochemical and morphologic changes have been shown to occur during apoptosis, but their reflections on cellular functions are poorly understood. Interleukin-3 (IL-3)-dependent FDCP-1 (factor-dependent cell lines cloned in Paterson Laboratories) cells were studied for their ability to adhere to hemopoietic stroma in a temporal fashion under conditions of apoptosis and following rescue from apoptosis with growth factor. It was found that cloned FDCP-1 cells always maintained, in the presence of a source of IL-3 (either WEHI conditioned medium or rm-IL-3), bound cloned hemopoietic stromal cell GB1/6 in a constant fashion for 20 hours, while cells starved of IL-3 experienced a 50% time-dependent decrement in binding. If IL-3 were added back to FDCP-1 that had been starved of growth factor for 8 hours, but not 12 hours, adherence to stroma was restored to that of control cells always in the presence of IL-3. Granulocyte/macrophage colony-stimulating factor (GM-CSF), Interleukin-6 (IL-6) and transforming growth factor-beta (TGF-beta) did not restore cytoadherence. By transmission electron microscopy, nucleus and cytoplasm of IL-3-replenished cells resembled that of control cells. These data indicate that at least some events related to apoptosis were reversible for a period up to 8 hours, but not 12 hours, in cells that had been rescued by readdition of IL-3. These findings offer important insight into a way in which bone marrow progenitor cells may be maintained in a condition that optimizes their ability to engraft stroma during transplantation.

Isolation of human bone marrow myeloid cells by ion exchange filtration.

A method is described for the separation of early and intermediate myeloid cells from human bone marrow aspirates. This easily performed procedure is based on preferential binding of lymphoid and late myeloid cells to DEAE-Cellulose-Sephadex G-25 columns.

Abnormal marrow fibroblasts in aplastic anemia.

Human bone marrow fibroblasts (BMF) were grown in vitro from normal (N) subjects and patients with aplastic anemia (AA). Growth studies in vitro revealed that both the N-BMF and AA-BMF had a logarithmic growth phase of eight days. Population doubling time for six of the 12 N-BMF and seven of the 12 AA-BMF was greater than 50 h. Five of the 12 AA-BMF studied in contrast to only two of the 12 N-BMF had a population doubling time of less than 50 h. The remaining four N-BMF had a population doubling time of greater than 100 h. During a similar duration in the logarithmic phase of growth, the AA-BMF underwent an average of 2.499 population doublings in comparison to 1.586 doublings by N-BMF (P = less than 0.01). The AA-BMF grew in multiple layers compared with the N-BMF, which usually grew as a monolayer. At the end of the logarithmic phase of growth, the AA-BMF also had a significantly higher number of cells per dish than the N-BMF (P = 0.02 on analysis of variance and covariance). These data suggest that a subgroup of AA-BMF grows faster than N-BMF and that the AA-BMF lack cell-to-cell inhibition. Testosterone, 3 alpha-etiocholanolone, and dexamethasone at 1 X 10(-8)M concentration, a physiological concentration, stimulated the growth of N-BMF as evidenced by increase in cell numbers and radioactive thymidine (3H-TdR) uptake. While dexamethasone had a stimulating effect on growth of N-BMF, it suppressed the growth of AA-BMF. Specific binding of radioactive dexamethasone (3H-dexa) was determined both for the N-BMF and AA-BMF. Specific binding sites for dexamethasone (Bmax) present on the N-BMF ranged from 460 to 770 fmol/mg protein). Bmax for AA-BMF was low (27-215 fmol/mg protein). In addition, the dissociation constant (Kd) was ten times lower for AA-BMF (1.0 X 10(-7) M) than for N-BMF (1.1 X 10(-8) M). The observations on the growth studies, the paradoxical response to dexamethasone, and the difference in the number of binding sites for dexamethasone indicate that the marrow fibroblasts from patients with aplastic anemia are abnormal.

Growth of human malignant micromegakaryocytes in vitro.

Mononuclear cells from the peripheral blood of a patient with megakaryoblastic transformation of Philadelphia chromosome-positive chronic myelogenous leukemia were cultured. Morphological and cytochemical studies and cell ploidy determinations were done daily for 4 days. PAS staining of the cells increased progressively during culture. Ultrastructural study of circulating and cultured cells revealed demarcation membranes and alpha granules indicating the cells were micromegakaryocytes. Deoxyribonucleic acid synthesis, determined by 3H-thymidine uptake, peaked at 72 hours. The DNA content of cultured cells was diploid at all times. All 15 metaphases analyzed at 72 hours were Ph1-positive. Malignant (Ph1-positive) megakaryoblasts and micromegakaryocytes grown successfully were capable of partial cytoplasmic maturation as demonstrated by glycogen deposition and increase in subcellular organelles, while endoreduplication was impaired. Malignant megakaryoblasts and micromegakaryocytes can be grown successfully in short term liquid culture and have more complete maturation in vitro than observed in vivo.

Membrane-associated proteoglycans produced by Sertoli cells are not randomly distributed on the cell surface.

Sertoli cells in culture synthesize two membrane-associated proteoglycans (PGs) containing as glycosaminoglycan (GAG) moieties either chondroitin sulfate (CS) or CS and heparan sulfate (HS); the latter PG is, therefore, referred to as the mixed PG. To determine if these PGs are randomly distributed on the cell surface, Sertoli cell monolayers were treated with chondroitinase ABC, and then the remaining PGs were analyzed by DEAE-Sephacel chromatography. The results obtained with Sertoli cell monolayers show that the CS of the mixed PG is degraded by chondroitinase, while the CS-PG is not degraded. In contrast, chondroitinase treatment of Sertoli cells in suspension shows that both the mixed PG and the CS-PG are degraded. From this, it is inferred that the mixed PG is apically oriented and the CS-PG is basolaterally oriented. Studies of the adhesion of germ cells to Sertoli cell monolayers give further support to the apical location of the mixed PG and suggest that its HS moiety is involved in the attachment of germ cells to Sertoli cells.

The sulfation degree of membrane-associated proteoglycan from a hemopoietic cell line is determined by changes in the growth state of the cell.

Multipotential hemopoietic progenitor cells (FDCP-mix) proliferate in culture medium supplemented with horse serum. When transferred to a medium without serum, cells do not proliferate and enter a quiescent state. Both proliferative and quiescent cells synthesize only chondroitin sulfate proteoglycan (CS-PG) which is associated to the cell membrane. Incorporation of 35SO4 into CS-PG was 4-fold higher in quiescent than in proliferative cells. Flow cytometric studies using monoclonal antibodies which recognize the core protein or the CS chains, showed that the increased uptake of sulfate was not the consequence of an increase in the abundance of CS-PG. Further characterization demonstrated that CS-PG isolated from quiescent cells exhibited a slightly higher hydrodynamic size than CS-PG from proliferative cells. However, the glycosaminoglycan chains from PG derived from proliferative and quiescent cells have the same hydrodynamic size. Through ion-exchange chromatography we observed that the mean charge density of PG from quiescent cells was higher than in proliferative cells, suggesting a higher sulfation degree from PG synthesized by quiescent cells. This was confirmed by flow cytometric studies using monoclonal antibody 2B6, which recognizes the unsaturated terminal disaccharide of chondroitin-4-O-sulfate.

Pelvic insufficiency fractures in patients with pelvic irradiation.

BACKGROUND: Insufficiency fractures (IF) occur as a result of normal physiological stress on bones with deficient elastic resistance. Pelvic insufficiency fractures are a complication of osteoporosis due to postmenopausal status, high dose of corticosteroids, or local irradiation. They are important because differential diagnosis includes pelvic bone metastases. Diagnosis is based on both clinical manifestations and radiographic and scintigraphic findings. METHODS AND MATERIALS: We examined eight patients with pelvic cancer who had previously undergone external beam radiation therapy as part of their treatment. In the follow-up, they developed insufficiency fractures, and no factor other than pelvic irradiation was present. Diagnosis was confirmed by radionuclide bone scan followed by conventional radiography and computed tomography (CT) scan. RESULTS: The average onset of symptoms was 13.7 months after radiation therapy was completed. The initial symptom in all cases was pain. In all of the patients, the bone scan showed abnormalities. One to four increased uptake foci were observed, in the sacroiliac joint in all cases, and in the pubis in three cases. The initial diagnosis was bone metastases in five patients. CT scan showed fractures in all of the patients, in sacrum and pubis, both endostic and cortical. Treatment, consisting of nonsteroidal anti-inflammatory drugs and rest, led to symptomatic relief in all cases. CONCLUSION: Knowledge of pelvic insufficiency fractures is essential in order to rule out metastasic disease, and thus avoid inaccurate treatment. Although radionuclide bone scan is useful in early detection of pelvic IF, definitive diagnosis is provided by CT scan.

Ferrochelatase deficiency in an infant with anemia and growth delay.

A 5-month-old infant with hypochromic anemia and iron overload secondary to ferrochelatase (heme synthetase) deficiency is described. Decreased activity of iron-containing enzymes in the absence of any other proven cause is suggested as the main cause of the associated growth retardation.

Collagenase-like activity associated to the leukemic WEHI-3B cell line.

The leukemic cell line, WEHI-3B presents a latent collagenase-like activity which is activated after trypsin treatment. The enzymatic activity is not released from cells and is specific for the degradation of interstitial collagens. After attachment of WEHI cells to a hemopoietic stroma derived from long-term bone marrow cultures, the organization of the stroma is disrupted. This effect was not observed after the attachment to stroma of normal progenitor cells. These results suggest that the collagenase-like activity in leukemic cells may contribute through collagen degradation, to the disorganization of the marrow stroma. The latter was confirmed by the use of a labeled-collagen containing stroma, which was degraded when cocultured with WEHI cells, but not with normal progenitor cells.