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Phenotypic Heterogeneity of Cancer Associated Fibroblasts in Cervical Cancer Progression: FAP as a Central Activation Marker. Cells 2024; 13:560. [PMID: 38606999 PMCID: PMC11010959 DOI: 10.3390/cells13070560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 03/09/2024] [Accepted: 03/10/2024] [Indexed: 04/13/2024] Open
Abstract
Cervical cancer (CC) is the fourth leading cancer among women and is one of the principal gynecological malignancies. In the tumor microenvironment, cancer-associated fibroblasts (CAFs) play a crucial role during malignant progression, exhibiting a variety of heterogeneous phenotypes. CAFs express phenotypic markers like fibroblast activation protein (FAP), vimentin, S100A4, α-smooth muscle actin (αSMA), and functional markers such as MMP9. This study aimed to evaluate the protein expression of vimentin, S100A4, αSMA, FAP, and MMP9 in mesenchymal stem cells (MSC)-CAF cells, as well as in cervical cancer samples. MSC cells were stimulated with HeLa and SiHa tumor cell supernatants, followed by protein evaluation and cytokine profile to confirm differentiation towards a CAF phenotype. In addition, automated immunohistochemistry (IHQa) was performed to evaluate the expression of these proteins in CC samples at different stages. Our findings revealed a high expression of FAP in stimulated MSC cells, accompanied by the secretion of pro/anti-inflammatory cytokines. In the other hand, CC samples were observed to have high expression of FAP, vimentin, αSMA, and MMP9. Most importantly, there was a high expression of their activation proteins αSMA and FAP during the different stages. In the early stages, a myofibroblast-like phenotype (CAFs αSMA+ FAP+), and in the late stages a protumoral phenotype (CAF αSMA- FAP+). In summary, FAP has a crucial role in the activation of CAFs during cervical cancer progression.
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Positive correlation between the nuclear expression of GPER and pGLI3 in prostate cancer tissues from patients with different Gleason scores. Front Endocrinol (Lausanne) 2024; 15:1333284. [PMID: 38370352 PMCID: PMC10870147 DOI: 10.3389/fendo.2024.1333284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2023] [Accepted: 01/11/2024] [Indexed: 02/20/2024] Open
Abstract
Prostate cancer (PCa) is the most prevalent cause of death in the male population worldwide. The G Protein-Coupled Estrogen Receptor (GPER) has been gaining relevance in the development of PCa. Hedgehog (Hh) pathway activation is associated with aggressiveness, metastasis, and relapse in PCa patients. To date, no studies have evaluated the crosstalk between the GPER and the Hh pathway along different group grades in PCa. We conducted an analysis of paraffin-embedded tissues derived from patients with different prognostic grade of PCa using immunohistochemistry. Expression and correlation between GPER and glioma associated oncogene homologue (GLI) transcriptional factors in the parenchyma and stroma of PCa tumors were evaluated. Our results indicate that GPER is highly expressed in the nucleus and increases with higher grade groups. Additionally, GPER's expression correlates with pGLI3 nuclear expression across different grade groups in PCa tissues; however, whether the receptor induces the activation of GLI transcriptional factors, or the latter modulate the expression of GPER is yet to be discovered, as well as the functional consequence of this correlation.
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YKL-40 serum levels are predicted by inflammatory state, age and diagnosis of idiopathic inflammatory myopathies. Sci Rep 2023; 13:19172. [PMID: 37932407 PMCID: PMC10628093 DOI: 10.1038/s41598-023-46491-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 11/01/2023] [Indexed: 11/08/2023] Open
Abstract
YKL-40 increase according to the aging process, and its functions have been associated with tissue remodeling and systemic inflammation. In Rheumatoid Arthritis (RA) it has been proposed as a possible biomarker of activity and severity, however; in the field of idiopathic inflammatory myopathies (IIM) the role of YKL-40 in IIM is not clear. Thus, we aimed to evaluate if there is an association between the serum levels and muscle tissue expression of YKL-40 with age, IIM phenotype, muscle strength and myositis disease activity. The main finding was that age is the most important variable that affects the YKL-40 serum levels. In muscle biopsy, we observed that YKL-40 is mainly expressed in infiltrating lymphoid cells than in muscle tissue. Using ANCOVA according to the b-coefficients, YKL-40 serum levels are predicted by inflammatory state, age, and IIM diagnosis.
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Pleiotrophin and the Expression of Its Receptors during Development of the Human Cerebellar Cortex. Cells 2023; 12:1733. [PMID: 37443767 PMCID: PMC10341181 DOI: 10.3390/cells12131733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 06/19/2023] [Accepted: 06/24/2023] [Indexed: 07/15/2023] Open
Abstract
During embryonic and fetal development, the cerebellum undergoes several histological changes that require a specific microenvironment. Pleiotrophin (PTN) has been related to cerebral and cerebellar cortex ontogenesis in different species. PTN signaling includes PTPRZ1, ALK, and NRP-1 receptors, which are implicated in cell differentiation, migration, and proliferation. However, its involvement in human cerebellar development has not been described so far. Therefore, we investigated whether PTN and its receptors were expressed in the human cerebellar cortex during fetal and early neonatal development. The expression profile of PTN and its receptors was analyzed using an immunohistochemical method. PTN, PTPRZ1, and NRP-1 were expressed from week 17 to the postnatal stage, with variable expression among granule cell precursors, glial cells, and Purkinje cells. ALK was only expressed during week 31. These results suggest that, in the fetal and neonatal human cerebellum, PTN is involved in cell communication through granule cell precursors, Bergmann glia, and Purkinje cells via PTPRZ1, NRP-1, and ALK signaling. This communication could be involved in cell proliferation and cellular migration. Overall, the present study represents the first characterization of PTN, PTPRZ1, ALK, and NRP-1 expression in human tissues, suggesting their involvement in cerebellar cortex development.
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Impaired muscle strength is associated with ultrastructure damage in myositis. Sci Rep 2022; 12:17671. [PMID: 36271295 PMCID: PMC9586957 DOI: 10.1038/s41598-022-22754-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 10/19/2022] [Indexed: 01/18/2023] Open
Abstract
The muscle fiber ultrastructure in Idiopathic Inflammatory Myopathies (IIM) has been scarcely explored, especially in Inclusion Body Myositis. The aim of this study was to implement the Scanning Electron Microscopy (SEM) in a small cohort of IIM patients, together with the characterization of immunological profile for a better understanding of the pathophysiology. For immunological profile characterization, we identified the presence of autoantibodies (Ro-52, OJ, EJ, PL7, PL12, SRP, Jo-1, PMScl75, PMScl100, Ku, SAE1, NXP2, MDA5, TIF1γ, Mi-2α, Mi-2β) and quantified cytokines (IL-1β, IFN-α2, IFN-γ, TNF-α, IL-6, IL-10, IL-12p70, IL-17A, IL-18, IL-23, IL-33) and chemokines (CCL2, CXCL8). The histological analysis was made by hematoxylin-eosin staining while the muscle fiber ultrastructure was characterized by SEM. We observed changes in the morphology and structure of the muscle fiber according to muscle strength and muscle enzymes. We were able to find and describe muscle fiber ultrastructure with marked irregularities, porosities, disruption in the linearity and integrity of the fascicle, more evident in patients with increased serum levels of muscle enzymes and diminished muscle strength. Despite the scarce reports about the use of SEM as a tool in all clinical phenotypes of IIM, our work provides an excellent opportunity to discuss and reframe the clinical usefulness of SEM in the diagnostic approach of IIM.
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In vitro Anticancer Activity of the Polar Fraction From the Lophocereus schottii Ethanolic Extract. Front Pharmacol 2022; 13:820381. [PMID: 35444555 PMCID: PMC9014087 DOI: 10.3389/fphar.2022.820381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 02/07/2022] [Indexed: 11/25/2022] Open
Abstract
Cancer is an increasingly common disease and is considered one of the main causes of death in the world. Lophocereus schottii (L. schottii) is a cactus used in Mexico in traditional medicine for cancer treatment. This study aimed to determine the effect of the ethanolic extract and the polar and nonpolar fractions of L. schottii in murine L5178Y lymphoma cells in vitro, analyzing their effect on the proliferative activity of splenocytes, and establishing the effective concentration 50 (EC50) of the polar fraction. In addition, the secondary metabolites present in the extracts were determined by ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). The study establishes that the three extracts of L. schottii have a cytotoxic effect on L5178Y cells and on the splenocytes stimulated with ConA. Additionally, the polar fraction has a significantly greater effect being three times more effective than cyclophosphamide on inhibiting the viability of L5178Y cells. Secondary metabolites present are mainly flavonoids and alkaloids, but there are also some terpenoids and sterols. Ultimately, polar fraction can be considered an anticancer substance, since its EC50 of 15 μg/mL is within the parameters established by the National Cancer Institute.
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ERp57 EXPRESSION IN LOCALLY ADVANCED LARYNGEAL SQUAMOUS CELL CARCINOMA AND THEIR RELATION WITH CLINICOPATHOLOGIC PARAMETERS. Oral Surg Oral Med Oral Pathol Oral Radiol 2021. [DOI: 10.1016/j.oooo.2021.03.119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Central role of the placenta during viral infection: Immuno-competences and miRNA defensive responses. Biochim Biophys Acta Mol Basis Dis 2021; 1867:166182. [PMID: 34058350 DOI: 10.1016/j.bbadis.2021.166182] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 05/04/2021] [Accepted: 05/19/2021] [Indexed: 12/21/2022]
Abstract
Pregnancy is a unique immunological condition in which an "immune-diplomatic" dialogue between trophoblasts and maternal immune cells is established to protect the fetus from rejection, to create a privileged environment in the uterus and to simultaneously be alert to any infectious challenge. The maternal-placental-fetal interface (MPFI) performs an essential role in this immunological defense. In this review, we will address the MPFI as an active immuno-mechanical barrier that protects against viral infections. We will describe the main viral infections affecting the placenta and trophoblasts and present their structure, mechanisms of immunocompetence and defensive responses to viral infections in pregnancy. In particular, we will analyze infection routes in the placenta and trophoblasts and the maternal-fetal outcomes in both. Finally, we will focus on the cellular targets of the antiviral microRNAs from the C19MC cluster, and their effects at both the intra- and extracellular level.
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Multiple calcifying hyperplastic dental follicles: a major diagnostic consideration in multiple pericoronal lesions - report of two cases. BMC Oral Health 2020; 20:159. [PMID: 32487188 PMCID: PMC7268393 DOI: 10.1186/s12903-020-01146-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 05/21/2020] [Indexed: 11/16/2022] Open
Abstract
Background Pericoronal radiolucent lesions are a common radiographic finding, but it is rare that they occur in multiple forms. Multiple calcifying hyperplastic dental follicles (MCHDF) are entities with few cases described to date; nevertheless, they appear to have a very particular phenotypic pattern. Cases presentation Case 1: A 10-year-old male was evaluated radiographically, revealing four impacted canines, each accompanied by unilocular pericoronal radiolucency. Case 2: A 16-year-old male was planning orthodontic treatment; following his radiological evaluation all third molars were found to be accompanied with pericoronal radiolucencies. Enucleation, and third molar removal along with the pericoronal tissue were the respective treatments. Microscopically, in both cases, the specimens shown odontogenic epithelium, and type I and II calcifications in the hyperplastic follicles, all these characteristics were consistent with MCHDF. Conclusion Although MCHDF are a rare entity, they must be considered in the differential diagnosis of multiple pericoronal lesions. Under the light of the current evidence, the histological findings may be relatively heterogeneous, but their integration with both the clinical data, which are apparently particular, and with the radiographic characteristics, can lead to a definitive diagnosis.
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Alliin, an Allium sativum Nutraceutical, ReducesMetaflammation Markers in DIO Mice. Nutrients 2020; 12:nu12030624. [PMID: 32120804 PMCID: PMC7146142 DOI: 10.3390/nu12030624] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 02/22/2020] [Accepted: 02/25/2020] [Indexed: 02/06/2023] Open
Abstract
Obesity generates a chronic low-grade inflammatory state which promotes oxidative stress and triggers comorbidities. Alliin is the main organosulfur compound in garlic and has been shown to induce a decrease in the expression of proinflammatory cytokines; its systemic effect on metabolic parameters and adipose tissue is not yet known, however. After nine weeks of HFD and with obesity established in C57BL/6 mice, we observed that a daily treatment with alliin for 3.5 weeks (15 mg/kg) did not affect body weight, but significantly improved insulin sensitivity and glucose tolerance, both evaluated through a blood glucose monitoring system. Once alliin treatment was completed, serum, adipose tissue, and organs of interest related to metabolism were removed for further analysis. We observed that alliin significantly decreased the size of adipocytes from epididymal adipose tissue, evaluated via microscopy. A decrease in gene expression and serum protein levels of the adipocytokines leptin and resistin, as well as decreased serum IL-6 concentration, were detected by qRT-PCR and ELISA, respectively. It did not, however, affect mRNA expression of antioxidant enzymes in the liver. Taken altogether, these results indicate that treatment with alliin reduces metaflammation markers in DIO mice and improves some metabolic parameters without affecting others.
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Minimally invasive asterional approach for microvascular decompression in trigeminal neuralgia. GAC MED MEX 2019; 155:S56-S63. [PMID: 31638613 DOI: 10.24875/gmm.m19000291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Objective Trigeminal neuralgia (TN) is a neuropathic disorder that can be treated surgically. This study aimed to present the surgical findings and the clinical outcomes of 26 patients with TN treated by minimally invasive asterional surgery. Methods Longitudinal descriptive study. Twenty-six patients with TN underwent minimally invasive asterional surgery. The medical history, surgical findings, therapeutic response, and complications were registered. They were followed for 36 months. Results Nineteen cases were associated with vascular compression; five were associated with arachnoiditis. The two remaining cases were associated with multiple sclerosis and post-herpetic neuralgia. The pain was substantially reduced in all patients in the immediate postoperative period. At 36 months, in 25 patients, total or acceptable pain control was achieved. In the long term, 22 patients evolved with no permanent complications. Conclusion The microvascular decompression surgery by an asterional approach is an alternative with similar results to the classic retrosigmoid approach to treat TN, but that adds the benefits of the principles of minimally invasive surgery. Constant efforts need to be made to optimize minimally invasive surgical techniques for TN.
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[Abordaje asterional mínimamente invasivo para descompresión microvascular en neuralgia del trigémino]. GAC MED MEX 2019; 155:S70-S78. [PMID: 31182878 DOI: 10.24875/gmm.19005130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Objective Trigeminal neuralgia (TN) is a neuropathic disorder that can be treated surgically. This study aimed to present the surgical findings and the clinical outcomes of 26 patients with TN treated by minimally invasive asterional surgery. Methods Longitudinal descriptive study. Twenty-six patients with TN underwent minimally invasive asterional surgery. The medical history, surgical findings, therapeutic response, and complications were registered. They were followed for 36 months. Results Nineteen cases were associated with vascular compression; five were associated with arachnoiditis. The two remaining cases were associated with multiple sclerosis and post-herpetic neuralgia. The pain was substantially reduced in all patients in the immediate postoperative period. At 36 months, in 25 patients, total or acceptable pain control was achieved. In the long term, 22 patients evolved with no permanent complications. Conclusion The microvascular decompression surgery by an asterional approach is an alternative with similar results to the classic retrosigmoid approach to treat TN, but that adds the benefits of the principles of minimally invasive surgery. Constant efforts need to be made to optimize minimally invasive surgical techniques for TN.
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Modified Orbitozygomatic Approach without Orbital Roof Removal for Middle Fossa Lesions. J Korean Neurosurg Soc 2018; 61:407-414. [PMID: 29631381 PMCID: PMC5957324 DOI: 10.3340/jkns.2017.0208] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 10/10/2017] [Accepted: 11/03/2017] [Indexed: 11/27/2022] Open
Abstract
Objective The purpose of the present study was to describe an OrBitoZygomatic (OBZ) surgical variant that implies the drilling of the orbital roof and lateral wall of the orbit without orbitotomy. Methods Design : cross-sectional study. Between January 2010 and December 2014, 18 patients with middle fossa lesions underwent the previously mentioned OBZ surgical variant. Gender, age, histopathological diagnosis, complications, and percentage of resection were registered. The detailed surgical technique is described. Results Of the 18 cases listed in the study, nine were males and nine females. Seventeen cases (94.5%) were diagnosed as primary tumoral lesions, one case (5.5%) presented with metastasis of a carcinoma, and an additional one had a fibrous dysplasia. Age ranged between 27 and 73 years. Early complications were developed in four cases, but all of these were completely resolved. None developed enophthalmos. Conclusion The present study illustrates a novel surgical OBZ approach that allows for the performance of a simpler and faster procedure with fewer complications, and without increasing surgical time or cerebral manipulation, for reaching lesions of the middle fossa. Thorough knowledge of the anatomy and surgical technique is essential for successful completion of the procedure.
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Multiple Sclerosis in Search for Biomarkers: Gender as a Variable in the Equation. ACTA ACUST UNITED AC 2018. [DOI: 10.3233/nib-170126] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Anatomy of the olfactory nerve: A comprehensive review with cadaveric dissection. Clin Anat 2017; 31:109-117. [DOI: 10.1002/ca.23003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 10/16/2017] [Accepted: 10/25/2017] [Indexed: 11/11/2022]
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[Intracranial tumor behavior of plasma cell neoplasms. Report of 2 cases and literature review]. CIR CIR 2013; 81:431-435. [PMID: 25125061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
BACKGROUND Multiple myeloma is a plasmatic cell neoplasm that is characterized by skeletal destruction, renal failure, anemia and hypercalcemia. The skull plasmacytomas represent less than 1% of the head and neck tumors, they can be the primary lesion or occur as a secondary manifestation of multiple myeloma in 20-30% of the patients, or they can even manifest several years later after the diagnosis of plasmacytoma. Although some of the lesions may be surgically accessible, the aggressive natural behavior will complicate the evolution of the patients. We present two cases of Mexican women with intracranial plasmacytomas, one of them associated with multiple myeloma. CLINICAL CASES The first case was a 24 year-old woman diagnosed with a multiple myeloma with plasmacytic-plasmablastic bone infiltration that was removed in 90%. She presented a local recurrence that required a second intervention for removal. The second case was a 62 year-old female with a malignant intracranial tumor of plasma cells that was totally resected. Both patients received adjuvant treatment based on chemotherapy and radiation therapy with favorable results. The patients died at 5 and 1.5 years respectively due to renal failure secondary to systemic disease. CONCLUSIONS We propose chemotherapy and radiation therapy as an essential part of treatment for this condition, as the aggressive behavior of the neoplasms can complicate the evolution, despite being surgically accessible.
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Ping pong fractures: treatment using a new medical device. Childs Nerv Syst 2013; 29:679-83. [PMID: 23274633 DOI: 10.1007/s00381-012-1979-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Accepted: 11/16/2012] [Indexed: 11/30/2022]
Abstract
PURPOSE The aim of this study was to assess the use of a new medical device to elevate depressed skull fractures (DSFs) in newborns and minor infants. METHODS Nine patients (ranging from 1 day to 9 months of age) with simple DSF underwent skull elevation by a new elevator medical device. This medical device comprises two elements: a pediatric resuscitator (CPR mask) connected to a 50-ml syringe. Pediatric CPR face mask is placed on the depressed region and negative pressure is generated through syringe plunger elevation until fracture reduction is observed. RESULTS Fracture reduction was confirmed in eight of nine patients by computed tomography scan without underlying brain damage and associated complications. Skull asymmetry was eliminated recovering normal shape. Up to now, there are no neurological concerns. Another treatment was chosen to be applied for one patient who did not respond to manipulation. CONCLUSION The new device is a safe, affordable, and effective choice in the treatment of simple depressed skull fractures in newborns and minor infants.
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[Clinical trials without statistical significance. Importance of type II error]. CIR CIR 2008; 76:271-275. [PMID: 18647564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
A randomized clinical trial is a prospective experiment to compare one or more interventions against a control group, in order to determine the effectiveness of the interventions. A clinical trial may compare the value of a drug vs. placebo. It may compare surgical with medical interventions. The principles apply to any situation in which the issue of who is exposed to which condition is under the control of the experimenter, and that the method of assignment is through randomization. A negative clinical trial is that in which no significant difference is found between the comparison groups. Results without statistical difference may be useful either to discard useless treatments or to demonstrate that one intervention is as effective as the one it was compared with. Eliminating useless treatments may be adequate. However, if this is the result of studies with methodological errors, new interventions that are actually useful may not be available for patients. In this review we present some of the possible methodological errors that may lead to false negative results in clinical trials.
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